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Geiger
Counter
RockOn! 2009
1
RockOn! 2009
What Are We Building ?
2
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Geiger
Counter
Background
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3
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Radiation: Overview
- Radiation is generally viewed as
harmful to space payloads.
- While some projects purposely
expose parts to the saturated
Van Allen belts to investigate
the effects of high energy
particles, some projects must
avoid harmful doses at all costs.
- Sparse data has been collected
from suborbital airspace.
Van Allen Belts: www.nasa.gov
- This payload will allow for a
large collection of data sets.
4
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Radiation: Effects
- Single event phenomenon
(SEP), burnouts and bit flips
can cause damage to solid
state devices aboard a space
payload.
- An understanding of dose
levels is ideal to plan a
mission to sub-orbital
altitudes, especially with
sensitive optics or
microprocessors.
SEP diagram: www.aero.org/
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Radiation: Effects
- There are three types of radioactive
emissions:
- Alpha - the least penetrating form of
radiation, can be stopped with a piece
of paper or a few inches of air.
- Beta-rays are more penetrating than
alpha-rays
- Gamma-rays are the most penetrating
form of radiation. Often produced in
conjunction with alpha or beta-rays,
they can penetrate several inches of
steel or hundreds of feet in air.
Particle comparison:
www.freedomforfissi
on.org.uk
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Radiation: A General Trend
- Radiation levels roughly
double every 5000 feet in
altitude, so at sea level
dosage will be roughly ½
the level observed in
Denver, Colorado.
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Radiation: A General Trend
- However, radiation levels do depend on the level of
cosmic radiation, effective shielding, and any ground
or building materials containing radioactive
materials.
- In general, at sea level; you should see 12-14 counts
per minute.
- This device has resolution to 2 μs. Which indicates it
cannot detect particle events closer than 2 μs to each
other.
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Radiation: A General Trend
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Radiation: Dosage and Limits
-Max dose for occupational workers
(Nuclear Power) 5 Rem/yr (max
exposure to retina). [2]
Shielding can
drastically reduce
the observed dose.
Be sure to wear
safety glasses
when handling the
material.
-Max dose recommended for the
general public 100 mRem from a
high energy source over a short
time frame. [2]
-An average American receives 360
mRem/yr from natural background
and manmade sources. [2]
[2]
http://www.jlab.org/div_dept/train/
rad_guide
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Radiation: Comparisons
-A typical radiation dose from a chest x-ray is about 10
mRem per x-ray (Gamma exposure) [2]
-Consumer products contain radiation, such as: smoke
detectors, and lantern mantles. This dose is relatively
small as compared to other naturally occurring sources
of radiation and averages 10 mRem in a year (Alpha
exposure). [2]
20th Century Fox ©
11
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Radiation: Conversions
- Generally, 75 counts per minute
(CPM) is equivalent to 1
mRem/hr.
- Therefore, 4500 CPM is roughly
equivalent to 1 mRem
- A source from a smoke detector
makes up 2.8% of the yearly
average expected dose, which is
.027 mRem/day or .0012
mRem/hr
- These numbers shouldn’t alarm
you, an average person receives
1 mRem per day.
20th Century Fox ©
12
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What Are We Building ?
- Basic Geiger Counter
- Audio and Visual Cues for Radiation Detection
- Can detect Alpha, Beta, and Gamma Radiation.
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Organization:
The boards may seem like an array of confusing
electronics, but one can easily break the board into
smaller subsystems of related components.
This build is organized by different sub systems integral
to the board.
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Integral Systems:
- Geiger Tube
- MC14049CP Hex Inverter
- LN555C 555 Timer
- Mini Step-up Transformer
- GS 7805 5V Voltage Regulator
- IRF830 Power MOSFET
15
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Safety/Background
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Board Safety:
Caution:
Many of the components used in this workshop are
sensitive to electrostatic discharge (ESD). Please ensure
that you are wearing your protective wrist strap at all
times. There will be a warning slide when components
are ESD and heat sensitive.
Clipping leads can sometimes cause them to separate in
a rapid manner that could cause injury. Please take
caution when clipping leads. Wear your safety glasses at
ALL TIMES!
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Reading a Resistor:
The resistors in this workshop
have already been organized by
value.
In the event that your resistors
get mixed, please refer to the
chart at the left to classify your
resistors, or use your multimeter
If you are unsure, don’t hesitate
to raise your hand and ask for
assistance.
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Verifying Kit
Contents
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Prep Step 1: Tool Layout
- Prepare tools for the
construction process.
- Put on your safety
glasses.
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Prep Step 2: Grounding
- Put on a static strap to remain
grounded. Also make sure the strap
is tight across your wrist.
- This will protect any parts from
electro-static discharge (ESD) and its
harmful effects.
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Prep Step 3: Soldering Station
- Turn on the soldering iron
- Set the temperature control on
the soldering iron to a
temperature less than 700 °F
and greater than 450 °F.
- As a general rule use a
temperature in the range
between 550 and 650 degrees
Fahrenheit.
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Prep Step 3: Soldering Station
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Prep Step 4: Tinning the iron
- Tin the tip of the soldering
iron by melting an inch or so
of solder on the tip.
- The iron will now look shiny
on the tip.
- Then wipe any excess solder
on the golden sponge.
- Now place the iron back into
the holder. Tinning your
soldering iron in this manner
will aid in future soldering.
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Prep Step 4: Tinning the iron (close-up)
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Pre-Bending:
Pre-Bending 101:
- Pre-bending is a technique that allows
components to be easily inserted into a
PCB.
- Pre-bending also allows components to lay
more flush with the board.
- Bending components to the correct bend
radius takes practice, but mastering the
technique will reap rewarding benefits!
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Pre-Bending:
Pre-Bending 101:
- Start with the bending and prodding tool in
the position shown in the top picture.
- Choose a location along the length of the
tool that will yield the appropriate bend
radius.
90°
- Use your thumb to bend the lead such that
the component and lead are orthogonal.
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Verify Kit Contents
- Open your kits and verify the contents with the provided list
and visual layout.
- Find the Geiger Mueller (GM) Tube and set it aside in a safe
place.
- You won’t need the GM Tube until the last few steps.
GM TUBE
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Verify Kit Contents: Resistors
-R1 = 4.3 KΩ = (YOR)
-R2 = 15 KΩ = (BrGrO)
-R3 = 5.6 KΩ = (GrBlR)
-R4 = 470 KΩ = (YVY)
-R5 = 10 MΩ = (BrBkBl)
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Verify Kit Contents: Resistors
-R7 = 150 KΩ = (BrGrY)
-R8 = 470 Ω = (YVBr)
-R9 = 330 Ω = (OOBr)
-R14 = 220 KΩ = (RRY)
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Verify Kit Contents: Capacitors
- Some capacitors have polarity, while others do not.
Majority of capacitors used are not polarized.
- *Note C4=C5 and C3=C10.
- Some capacitors in use can carry charge long after power
has been disconnected from the circuit (15-30 seconds).
- Use caution especially around the high voltage (HV) section
of the circuit to avoid a discharge shock.
- The capacitors near the HV section have the capability of
holding a 1 KV burst and will SHOCK YOU if touched with
power connected or shortly after power is disconnected!
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Verify Kit Contents: Capacitors
- C1 = Green Ceramic 0.0047 μF @ 20V
- C2 = Green Ceramic 0.01 μF @ 100V
- C3(±) = Black Electrolytic 220 μF @ 10V
- C4 = Orange Ceramic 0.1 μF @ 1KV
- C5 = Orange Ceramic 0.1 μF @ 1KV
C1
C2
C3
+
C4
C5
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Verify Kit Contents: Capacitors
- C7 = Green Ceramic or Orange Ceramic 0.047 μF @100V
- C8 = Green Ceramic 0.01 μF @ 100V
- C10(±) = Black Electrolytic 220 μF @ 10V
- C12 = Orange Ceramic 120 pF @100V
C7
C8
+
C10
C12
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Verify Kit Contents: Diodes
- All diodes in this kit have polarity
- *Note these similar diodes D5=D6 , D2=D3=D9
- D1 = 1N914 =
- D2 = 1N4007 @ 1KV =
- D3 = 1N4007 @ 1KV =
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Verify Kit Contents: Diodes
- D4 = 1N5271 @ 100V =
- D5 = 1N5281 @ 200V =
- D6 = 1N5281 @ 200V =
- D9= 1N4007 @ 1KV =
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Verify Kit Contents: Diodes
- D10 = 1N75 @ 5.1 V =
- D11= 1N914=
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Verify Kit Contents: Miscellaneous
Q1 (IRF830)
Q4 (NPN Transistor)
Q3 (7805 Regulator)
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Verify Kit Contents: Miscellaneous
- D7 (Red Led)
-T1 (Mini Step-up Transformer)
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Verify Kit Contents: Miscellaneous
- U1 (16 pin 4049 chip
and socket)
- U2 (8 pin 555 Timer
chip and socket)
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Let’s Start
Building!
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40
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TIPS:
- The ESD wrist strap must be tight on your wrist at all times.
- DO NOT linger on parts with the soldering iron.
- As a general rule use a 3-5 second linger time with a 10-20
second cool time for parts.
- Mount and solder components flush to the board unless
otherwise stated.
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TIPS:
- Use caution when clipping leads
to avoid flinging metal across
the room.
- All soldering must achieve a
good solder filet on the pad as
shown for circuit reliability.
workmanship.
nasa.gov
Example of a good solder filet
- Also clip the leads as shown in
the solder filet example with
little excess wire above the top
of the filet.
- Bend resistors and diodes using
your plastic tool as shown.
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Board Schematic:
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Board Schematic:
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Schematic Overview – Part Highlighting:
Part to be added
Part added previously
- Blue highlights indicate
parts will be added to the
board in the current
step.
- Green highlights indicate
components already on
the board but relevant to
the current step.
45
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Schematic Overview – Coordinates (A1):
Numbers across top
Letters along side
- All schematic close-ups
include coordinates so they
can be easily located in your
schematic printout.
- The coordinates correspond
to the letters across the side of
the schematic and the
numbers across the top.
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Current Sub System:
Geiger Counter Sub Systems:
Oscillator
High Voltage (Unregulated)
DC Voltage Regulation
High Voltage Regulation
Output Pulse
47
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Oscillator Circuit – Coordinates (A1):
- This circuitry creates an oscillatory square wave to switch the
primary windings of the mini step-up transformer on and off.
- The speed of this oscillation is determined from the RC circuit
design.
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Oscillator Circuit – Coordinates (B1):
Timing Resistor
- Here the capacitor
C1 acts like a switch.
Because of the setup
of the inverting
buffer pins, the
circuit will form a
rectified oscillating
square wave at U1D.
- This circuit oscillates
at a frequency
according to the time
constant from the RC
circuit. (~50 KHz)
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Special Resistors – Coordinates (B2 and B4):
- This includes the odd footprint soldering at the beginning of
the board construction.
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Let’s Start Building
- The board shall be oriented in this manner for the duration
of this kit construction unless indicated otherwise.
- Raise your hand for assistance if any issues arise.
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Step 1: R7 (150KΩ BrGrY)
- Mount and solder R7 into the
appropriate place on the PCB.
- **This resistor is in a location that
was originally designed for a
capacitor.**
- The PCB design requires the
awkward bending of the resistor.
- Consult the following pictures for
examples of this.
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Step 1: R7 (before)
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Step 2: R7 (mounting)
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Step 2: R14 (220KΩ RRY)
- Mount and solder R14 into the
appropriate place on the PCB.
- **This resistor is in a location that
was originally designed for a
capacitor.**
- The PCB design requires the
awkward bending of the resistor.
- Consult the following pictures for
examples of this.
55
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Step 2: R14 (before)
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Step 2: R14 (after)
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Step 3: 16 pin socket
- Mount and solder the 16 pin socket
to the appropriate location on the
PCB.
Notch
- **This chip socket has a defined
orientation note the notch on the
PCB as well as the socket itself.**
- Match notch to notch to allow the
correct orientation.
- Start by soldering opposite corners
of the socket to mount to the board
for easier soldering. Also ensure
the socket is flush with the board.
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Step 3: 16 pin socket (after)
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Step 4: C1 and C2
- Mount and solder C1 and C2 into
the appropriate places on the PCB.
- These capacitors are not polarized,
so the orientation of mounting will
not compromise performance.
- C1 (0.0047 μF @ 10V)
- C2 (0.01 μF @ 100V)
C1
C2
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Step 4: C1 and C2 (after)
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Step 4: C1 and C2 (after close-up)
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Step 5: D1 (1N914)
- Mount and solder D1 into the
appropriate place on the PCB.
- This diode is polarized.
D1
- Orient the diode to match the black
line on the diode to the line drawn
on the PCB.
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Step 5: D1 (before)
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Step 5: D1 (after close up)
- Notice the black line on the
diode matches the PCB
silkscreen.
- It is very important to mount
all diodes in the proper
orientation!
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Step 6: R1 R2 R3
- Mount and solder R1, R2, and R3
into the appropriate place on the
PCB.
= R1 (YOR)
- These resistors are not polarized, so
orientation will not effect
performance.
= R2 (BrGrO)
- Bend the leads of the resistor
around the provided plastic tool.
- This prevents stress fractures from
sharp angle bending.
= R3 (GrBlR)
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Step 6: R1 R2 R3 (before)
D1
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Step 6: R1 R2 R3 (after close up)
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Oscillator Circuit – Coordinates (A1):
- This circuitry creates an oscillatory square wave to switch the
primary windings of the mini step-up transformer on and off.
- The speed of this oscillation is determined from the RC circuit
design.
69
Highlight your schematic
RockOn! 2009
Oscillator Circuit – Coordinates (B1):
- Here the capacitor
C1 acts like a switch.
Because of the setup
of the inverting
buffer pins, the
circuit will form a
rectified oscillating
square wave at U1D.
Timing Resistor
- This circuit oscillates
at a frequency
according to the time
constant from the RC
circuit. (~50 KHz)
70
Highlight your schematic
RockOn! 2009
Special Resistors – Coordinates (B2 and B4):
- This includes the odd footprint soldering at the beginning of
the board construction.
71
Highlight your schematic
RockOn! 2009
Current Sub System:
Geiger Counter Sub Systems:
Oscillator
High Voltage (Unregulated)
DC Voltage Regulation
High Voltage Regulation
Output Pulse
72
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High Voltage (Unregulated) – Coordinates (A2):
Power MOSFET
- The power MOSFET
(Q1) stabilizes the voltage
switching on the primary
windings of T1 better
than the output of the
oscillator circuit can
provide.
- D2 and D3 rectify the
- This circuitry uses the oscillator
HVAC output to HV DC
circuit output through a mini step- with some voltage ripple.
up transformer to create the high
voltage (HV) needed for the
operation of the Geiger counter.
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High Voltage (Unregulated) – Coordinates (A2, A3):
- Rectified HV is
received after the
HV AC passes
through the two
rectifying diodes.
- The circuit is now nearing the desired HV
DC supply for the Geiger Tube! But why
is there still voltage ripple present?!
74
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High Voltage (Unregulated) – Coordinates (A2, A3):
- Using a HV
capacitor on
each output line
for the proper
voltage, the
voltage ripple is
smoothed.
Rectifying Diode
- The circuit is now nearing the desired HV
DC supply for the Geiger Tube!
- Each discharges
with a falling
peak and
recharges with a
rising peak.
75
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High Voltage (Unregulated) – Coordinates (A2, A3):
- The circuit is now at the desired HV DC
supply for the Geiger Tube!
- This technique is used frequently in
power electronics, and most electronics
can handle a small variation in voltage!
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Step 7: T1 CAUTION!!!
- Locate T1 (a four pronged
transformer) among your parts.
- This component is extremely
fragile, composed of very small
gauge wire twined around a few
nodes. The wires are surrounded
by brittle plastic connected to four
pins.
- If excess force is applied to these
metal pins the plastic will break
and sever the small wiring within
the transformer.
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Step 7: T1 CAUTION!!!
- Use CAUTION! The transformer
will fit into the PCB in one
orientation only.
D1
- **The transformer may not fit
perfectly. Try a dry fit at first to
note which leads may need
bending.
- If a lead does need bending use care
to slowly and gently bend the leads
with the plastic tool or a pair of
needle nose pliers.
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Step 7: T1 CAUTION!!!
- If you do force the transformer to
be flush with the PCB it WILL
break and render the kit useless.
T1
- Mount and solder T1 to the PCB.
- Match the dot on the transformer
to the dot on the PCB.
Example of flushness to board of T1
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Step 7: T1 (before)
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Step 7: T1
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Step 8: D2 D3
- Find D2 and D3 in the parts.
D2=D3
- Orient the diodes to match the grey
line with the line indicated on the
PCB.
- These diodes are polarized, mount
and solder these diodes in their
appropriate places on the PCB.
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Step 9: C4 and C5
- C4=C5 are not polarized ceramic
capacitors so their orientation does
not matter.
C4=C5
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Step 9: C4 and C5 (after close up)
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Step 10: Q1
- Find Q1 (IRF830) in the provided
parts.
- This transistor must be bent over to
lay flat on the board.
- Mount the transistor such that it
can be bent and lay flat on the
PCB.
- Now solder the transistor in place.
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Step 10: Q1 (bending)
- Pre-bend Q1 in the depicted
manner using the plastic tool.
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Step 10: Q1 (after close up)
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High Voltage (Unregulated) – Coordinates (A2):
Power MOSFET
- The power MOSFET
(Q1) stabilizes the voltage
switching on the primary
windings of T1 better
than the output of the
oscillator circuit can
provide.
- D2 and D3 rectify the
- This circuitry uses the oscillator
HVAC output to HV DC
circuit output through a mini step- with some voltage ripple.
up transformer to create the high
voltage (HV) needed for the
operation of the Geiger counter.
88
Highlight your schematic
RockOn! 2009
High Voltage (Unregulated) – Coordinates (A2, A3):
- Rectified HV is
received after the
HV AC passes
through the two
rectifying diodes.
- The circuit is now nearing the desired HV
DC supply for the Geiger Tube! But why
is there still voltage ripple present?!
89
Highlight your schematic
RockOn! 2009
High Voltage (Unregulated) – Coordinates (A2, A3):
- Using a HV
capacitor on
each output line
for the proper
voltage, the
voltage ripple is
smoothed.
Rectifying Diode
- The circuit is now nearing the desired HV
DC supply for the Geiger Tube!
- Each discharges
with a falling
peak and
recharges with a
rising peak.
90
Highlight your schematic
RockOn! 2009
High Voltage (Unregulated) – Coordinates (A2, A3):
- The circuit is now at the desired HV DC
supply for the Geiger Tube!
- This technique is used frequently in
power electronics, and most electronics
can handle a small variation in voltage!
91
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Current Sub System:
Geiger Counter Sub Systems:
Oscillator
High Voltage (Unregulated)
DC Voltage Regulation
High Voltage Regulation
Output Pulse
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DC Voltage Regulation (5V) – Coordinates (C1)
5V VCC OUTPUT
Rectifying Diode
5V VREG
- The output
VCC powers
the ICS and
other
components
on the board
- Using Q3 as a 5V voltage regulator VCC is maintained. C3 and
C10 serve as circuit protection in addition to the voltage
rectifying provided by D9.
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Step 11: C3 and C10
- Find C3 and C10 in the provided
parts.
- C3 and C10 are polarized
capacitors.
C3
C10
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Step 11: C3 and C10 (polarized capacitors)
White stripe marks
negative lead!
Also the negative
lead is shorter!
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Step 11: C3 and C10 (close up before)
Note the proper orientation of the
polarized capacitor by the + printed on
the silkscreen.
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Step 11: C3 and C10 (close up after)
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Step 12: Q3
- Find Q3 (7805 Voltage Regulator)
in the provided parts.
Q3
- This transistor must be bent over to
lay flat on the board.
- Leave enough space to allow a
digital out wire to pass underneath
this part in a later step!
- Mount the transistor such that it
can be bent and lay flat on the
PCB.
- Now solder the transistor in place.
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Step 12: Q3 (before)
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Step 12: Q3 (bending)
- Pre-bend Q3 in the depicted
manner using the plastic tool.
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Step 12: Q3 (after)
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Step 12: Q3 (after close up)
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Step 13: D9 and Power Bridge
- Bridge the left and middle holes of
the power section on the PCB as
shown using the lead clipping you
saved.
- Solder the bridge in place. This
removes the need for a bulky switch.
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Step 13: D9 and Power Bridge (before)
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Step 13: D9 and Power Bridge (before close up)
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Step 13: D9 and Power Bridge (after)
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Step 13: D9 and Power Bridge (after close up)
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DC Voltage Regulation (5V) – Coordinates (C1)
5V VCC OUTPUT
Rectifying Diode
5V VREG
- The output
VCC powers
the ICs and
other
components
on the board
- Using Q3 as a 5V voltage regulator VCC is maintained. C3 and
C10 serve as circuit protection in addition to the voltage
rectifying provided by D9.
108
Highlight your schematic
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Step 14:
Battery
Wiring
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Step 14: Battery Wiring Schematic
Red Battery Wire Connects +9V to the Power Bridge
Black Battery Wire Connects Battery Negative Terminal to Ground
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Step 15: 16 pin 4049 chip Full Schematic
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Step 14: Battery Wiring
- Find the Geiger counter
wiring in the provided
parts (red, black and
blue).
- Solder the red wire to the
V+ location on the PCB.
- Solder the black wire to
the dot GND location on
the PCB.
Black
Red
- Leave the blue wire free
for later installation.
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Step 14: Battery Wiring (before)
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Step 14: Battery Wiring (after)
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Step 14: Battery Wiring (after)
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Step 15: 16 pin 4049 chip
- Find the 16 pin 4049 chip (U1) in the
provided parts.
- Orient the dot toward the notch as
shown in the following pictures.
U1
- Match notch to notch on the chip
and socket.
- Either method will work.
- You may have to bend the leads in
slightly. Do so carefully.
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Step 15: 16 pin 4049 chip
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Step 15: 16 pin 4049 chip Pin Assignment
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Step 14: Battery Wiring Schematic
Red Battery Wire Connects +9V to the Power Bridge
Black Battery Wire Connects Battery Negative Terminal to Ground
119
Highlight your schematic
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Step 15: 16 pin 4049 chip Full Schematic
120
Highlight your schematic
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Step 16: HV Test 1st Powered Check
- Find one 9V test battery and
connect it to one of the two
9V connectors provided.
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Inspection
and High
Voltage (HV)
Test
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Step 16: HV Test 1st Powered Check
- Connect power to the circuit
using the header and two pin
adapter provided.
- Be sure to match the wires of
the three pin Geiger header
to the correct power and
ground wires on the battery
wires as shown.
- *note red matches red and
black matches black.
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Step 16: HV Test 1st Powered Check
- Locate the provided
voltmeter and set to 1,000 V
DC (depicted next slide).
- Touch the red (positive) lead
to the junction of C4 and D2.
- Touch the black (negative)
lead to the negative terminal
of the 9V battery.
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Step 16: HV Test 1st Powered Check
- The voltmeter should read
between 550-850 Volts
depending on component
tolerances.
- If it does, remove power and
prepare for the next step in a
few moments.
- If not; check the orientation
of the diodes on the board,
continuity of soldering joints,
and raise your hand.
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Current Sub System:
Geiger Counter Sub Systems:
Oscillator
High Voltage (Unregulated)
DC Voltage Regulation
High Voltage Regulation
Output Pulse
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High Voltage Regulation – Coordinates (A3):
- Zener Diodes
provide cheap
voltage
regulation.
- Conduct, if and
only if the voltage
across them is >
than their rated
voltage.
Rectifying Diode
- Dissipate enough
power to keep
voltage at the
appropriate value.
- The circuit is regulated to the needed 500V DC for the
Geiger tube by 3 Zener Diodes.
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Step 17: D4 D5 D6
- Locate D4, D5, and D6 in the
provided parts.
D4
- Match the black line to the
line on the PCB as shown.
- Mount and solder these
diodes in their required
locations on the PCB.
- **When bending make note
of the wider spacing of the
holes for mounting these
diodes.**
D5=D6
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Step 17: D4 D5 D6 (before)
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Step 17: D4 D5 D6 (after close-up)
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High Voltage Regulation – Coordinates (A3):
- Zener Diodes
are a cheap
voltage
regulation.
- Conduct to a
certain voltage.
- Dissipate extra
voltage as
current.
Rectifying Diode
- The circuit is regulated to the needed 500V DC for the
Geiger tube by 3 Zener Diodes.
Highlight your schematic
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High Voltage
(HV)
Regulation
Test
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Step 18: HV Test 2nd Powered Check
- Locate the provided
voltmeter and set to the 1,000
V DC setting.
- Find a 9V battery and apply
power to the circuit.
- Touch the red (positive) lead
to the junction of C4 and D2.
- Touch the black (negative)
lead to the negative terminal
of the 9V battery.
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Step 18: HV Test 2nd Powered Check
- The voltmeter should read
~500 Volts with little
deviation depending on
component tolerances and
battery charge.
- If it does, remove power and
prepare for the next step in a
few moments.
- If not check the orientation
of D4-D6 and raise your
hand.
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Current Sub System:
Geiger Counter Sub Systems:
Oscillator
High Voltage (Unregulated)
DC Voltage Regulation
High Voltage Regulation
Output Pulse
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Output Pulse Circuit – Coordinates (B2-C4):
Inverting Buffer Pin
Current Limiting Resistors
Regulating Zener Diode 5.1V
Cur. Limit R
Rectifier Diode
General Purpose Amplifier NPN Transistor
Indicator LED
Current limiting resistor
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Output Pulse Circuit – Coordinates (A3 & A4):
Current spike filter
Current limiting resistor
Geiger Tube
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Output Pulse Circuit
- Output is sent through many different indicators for each
radioactive particle detected.
- Audio is sent through a multi stage inverter to give extra current
push through the speaker amplifier transistor Q4. This will turn
Q4 on and result in an audible click.
- The original pulse is fed into a 555 timer configured in
monostable mode.
- This mode allows for a lengthening of a short pulse width to a
wider, more detectible pulse for the speaker setup and digital
output.
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Step 19: 555 Timer Socket
- Locate the 8-pin socket in the parts
- Note the Notch on the socket must
match the notch printed on the PCB
silkscreen.
- Solder opposite diagonal corners of
the socket first to allow ease of
soldering the remainder of the pins.
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Step 19: 555 Timer Socket (after)
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Step 19: 555 Timer Socket (after close up)
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Step 20: R4 and R5
- Locate R4 and R5 among the
provided parts.
- R4 = 470KΩ (YVBr)
- R5 = 10MΩ (BrBkBl)
- Mount and solder these
capacitors to the appropriate
location on the PCB.
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Step 20: R4 and R5 (before)
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Step 20: R4 and R5 (after close up)
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Step 21: C12
- Locate C12 in the provided
parts.
- C12 is an orange ceramic
capacitor
- Mount and solder these
resistors to the appropriate
location on the PCB.
C12
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Step 21: C12 (before)
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Step 21: C12 (after close-up)
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Step 22: R8
- Locate R8 470Ω (YVBr)
- Mount and solder this
resistor to the appropriate
location on the PCB.
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Step 22: R8 (before)
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Step 22: R8 (after close-up)
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Step 23: C7 and C8
- Locate the remaining green
ceramic capacitors.
- C7 = Green Ceramic or Orange
Ceramic 0.047 μF @100V
- C8 = Green Ceramic 0.01 μF @
100V
C7
C8
- Mount and solder these
components to the appropriate
location on the PCB.
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Step 23: C7 and C8 (before)
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Step 23: C7 and C8 (after close up)
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Step 24: 5.1V Zener Diode
- Locate the D10 1N75 diode.
- This diode serves as a pulse
limiter for the Geiger counter.
- Mount and solder this component
to the appropriate location on the
PCB.
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Step 24: 5.1V Zener Diode (before)
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Step 24: 5.1V Zener Diode (after close up)
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Step 25: D11 1N914 Zener Diode
- Locate the D11 1N914 diode.
- Mount and solder this
component to the appropriate
location on the PCB.
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Step 25: D11 1N914 Zener Diode (before)
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Step 25: D11 1N914 Zener Diode (after close up)
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Step 26: R9
- Locate R9 among the
provided parts.
- R9 330Ω (OOBr)
- Mount and solder this
resistor to the appropriate
location on the PCB.
+
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Step 26: R9 (before)
+
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Step 26: R9 (after)
+
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Step 27: Q4: 2N3904
- Locate Q4 among the
provided parts.
- Q4 is an NPN transistor with
one side rounded while the
other is square.
- This transistor serves as a
general purpose amplifier to
drive the speaker.
- Mount and solder this
resistor to the appropriate
location on the PCB.
+
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Step 27: Q4 (before)
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Step 27: Q4 (before close up)
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Step 27: Q4 (after)
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Step 27: Q4 (after close up)
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Step 28: D7-Red Led
- Locate D7 among the
provided parts.
- Mount and solder this diode
to the appropriate locations
on the PCB.
- Note the polarity of the
diode: The longer lead is
positive, the flat side is
negative, the flag points to
positive.
- All of these visual cues can
be used.
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Step 28: D7-Red Led (before)
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Step 28: D7-Red Led (before close up)
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Step 28: D7-Red Led (after close up)
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Step 29: Speaker
- Find the speaker in the
provided parts.
- It is polarized note the
polarity on the part and the
PCB.
Speaker
- Mount and solder the
speaker in the appropriate
location on the PCB.
- Now remove the seal over the
speaker.
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Step 29: Speaker (before)
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Step 29: Speaker (before close up)
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Step 29: Speaker (after close up)
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Step 30: Audio Bridge
- Find two scraps of leads to
bridge two locations in the
same manner used in the
power bridge.
- Bridge and solder into place
a wire across the two
leftmost holes in the Audio
section.
Audio Bridge
Headphone Bridge
- Bridge and solder into place
a wire across the top two
holes in the Headphone
section.
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Step 30: Audio Bridge (before)
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Step 30: Audio Bridge (after close up)
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Step 30: Headphone Bridge (after close up)
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Step 31: 555 Timer
- Locate U2 (555 Timer)
among the provided parts.
555 timer (U2)
- Mount this 8 pin chip to the
appropriate 8 pin socket on
the PCB.
- Note the dot on the chip and
mount as shown in the
following pictures.
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Step 31: 555 Timer (before close-up)
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Step 31: 555 Timer (after close-up)
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Step 31: 555 Timer (after close-up)
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Output Pulse Circuit – Coordinates (B2-C4):
Inverting Buffer Pin
Current Limiting Resistors
Regulating Zener Diode 5.1V
Cur. Limit R
Rectifier Diode
General Purpose Amplifier NPN Transistor
Indicator LED
Current limiting resistor
184
Highlight your schematic
RockOn! 2009
Output Pulse Circuit – Coordinates (A3 & A4):
Current spike filter
Current limiting resistor
Geiger Tube
185
Highlight your schematic
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Geiger Tube
Installation
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Step 32: Geiger Mueller (GM) Tube
- Find the GM Tube in the
provided parts.
- It is polarized. Note the
polarity on the part and the
PCB.
+
-
- On the tube the thin wire is
GM negative and the large
wire is GM positive.
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Step 32: What’s that on the end of the tube?!
- The tube is filled with an inert
gas to promote ionization in the
presence of radiation.
- The tube also has a very fragile
thin mica window to allow alpha
particles to pass through.
- This window will blow out in low
pressure environments.
- Don’t worry, this won’t
- The epoxy prevents blowout, but impact the merit of the kit
as the skin of the rocket
also eliminates some alpha
will block most alpha
particles from detection.
radiation.
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Step 32: GM Tube (Precautions)
- Do not overheat the GM
tube.
- When soldering, it can
overheat easily.
- Avoid the glass fill knob at
the rear of the tube. Shatter
this, and your tube won’t
work.
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Step 33: GM Tube-Positive Wire
- Find and strip ¼ inch from
each end of Red wire.
- Solder one of the striped
edges to the positive end of
the GM tube as shown.
- Be CAREFUL! Don’t let the
iron linger longer than 5
seconds before giving the
tube 10-15 seconds to cool.
- On the tube the thin wire is
GM negative and the large
wire is GM positive.
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Step 33: GM Tube-PCB Wiring
- Orient the tube on the bottom
of the board.
- Solder the free end of the red
wire into GM+ coming from
the bottom of the board up
through the hole.
- Solder the thin wire through
the GM – hole in the same
manner.
- Be CAREFUL! The thin
wire is frail and will snap if
bent too much.
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Step 33: GM Tube-PCB Wiring
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Step 33: GM Tube-PCB Wiring (before)
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Step 33: GM Tube-PCB Wiring (before close up)
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Step 33: GM Tube-PCB Wiring (close-up)
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Step 34: GM Tube-PCB Lacing
- Find the thin yellow wiring in the
provided parts.
- We will use this wire like shoelaces for
the mounting array on the GM PCB.
- Run the yellow wire through the first
two holes for each end as shown.
- The loose ends of the yellow wire
should extend upward through the
board.
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Step 34: GM Tube-PCB Lacing
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Step 34: GM Tube-PCB Lacing
- Begin a cross hatch method above and
below the board as if you are lacing a
tennis shoe.
- When you get to the end, loop back
following a similar pattern until about
6 inches of yellow wire remains.
- We will tie off the wire in the middle of
the mounting array, so keep this in
mind.
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Step 34: GM Tube-PCB Lacing
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Step 34: GM Tube-PCB Lacing
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Step 34: GM Tube-PCB Lacing
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Step 34: GM Tube-PCB Lacing
- Tie a
double
square
knot when
the lacing
of the GM
tube is
complete.
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Step 35: Data wire
- Strip the remaining
end of the blue data
wire and solder it in
place it to the
topmost pin of digital
out.
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Step 35: Data wire
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Final Product
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Final Product
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Smoke
Detector
Modification
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Overview:
- The Geiger counter that you assembled can detect all
three types of radiation: alpha, beta, and gamma.
- To test the Geiger counter, we will obtain a radioactive
source from the common household smoke detector.
- The common household smoke detector uses a very small
amount of Americium 241 to detect smoke particles in
the air.
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Safety:
- According to the World Nuclear Association [1],
Americium 241 is an alpha emitter that also emits some
low energy gamma rays.
- “Even swallowing the radioactive material from a smoke
detector would not lead to significant internal absorption
of Am-241, since the dioxide is insoluble.” [1]
- Caution: Although the sample is rather benign, do take
caution to keep it away from your face at all times.
- Caution: Also make sure that you wash your hands
before eating if you handle the sample.
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Let’s Begin!
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Step 1: Opening the detector housing
Opening the detector
housing and remove the lid.
Use the side cutters as a
fulcrum.
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Step 2: Visually inspect the detector
PCB
Radiation
Source
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Step 3: Separate the PCB from the detector housing
Clip wires
Bend inward and remove PCB from housing.
Close up
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Step 3: Separate the PCB from the Detector Housing
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Step 4: Cut PCB
Cut the PCB removing the radiation source portion.
Remove and
discard
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Step 4: Cut PCB
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Step 5: Remove Radiation Source
The PCB is glued to
a middle prongs.
Also release the
source from these
plastic holders.
Cut the PCB as
necessary! Be an
animal!!!
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Step 5: Remove Radiation Source
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Step 6: Clipping attachments
Clip the attachments
on the radiation
source with the pliers
until the source is
free.
Use brute force to
extract the source,
and don’t worry
about damaging the
remainder of the
detector as it is not
needed.
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Step 6: Clipping attachments
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Step 6: Clipping attachments
Remove the
remnants of the
PCB from the
radiation source.
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Step 7: The source is ready
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Final
Product:
Testing
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Final Product Testing
- Attach power to the circuit again.
- The Geiger counter should randomly blink
detecting usually 12-14 counts per minute
depending on sources in the area and
shielding.
- Acquire the provided alpha particle source
(taken from a smoke detector).
- Notice a large jump in the frequency of
counts.
- Each count represents the detection of a
radioactive particle by the Geiger counter.
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Final Product Testing
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Coronal
Discharge
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Coronal Discharge: An Overview
- Coronal discharge occurs in low pressure
environments with high voltages present.
- The air around a high potential (high
voltage) will become a conductor and emit a
bluish glow (plasma).
- This plasma will cause adverse effects for
the component as well as neighboring parts.
- The plasma is a bluish-purple and is visible
under normal lighting. (see images)
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Coronal Discharge: An Example
RockOn! Geiger counter seen through a vacuum chamber.
Area of
interest
near back
of D4-D6
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Coronal Discharge: An Example
Geiger counter seen through a vacuum chamber
Glow of
coronal
discharge
Close-up
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Coronal Discharge: The solution
- Coronal discharge is detrimental to parts.
- Dangerous to other payloads on the rocket.
- To mitigate these risks, we will add conformal coating to
the board to prevent coronal discharge.
- **Note: We will be in a pressurized environment on this
flight so this is not necessary, but is a good practice
especially with space applications.
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Conformal
Coating
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Step 1: Board Prep
- Take the board to a well
ventilated area (we will be
outside).
- Put on safety glasses and
rubber gloves.
- Place the board face up on
the prepared protected
surface.
- Shake the bottle lightly and
open it.
- MAKE SURE there is no
power on the board.
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Step 1: Board Prep
HV Section
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Step 2: Begin Coating
- Dip the brush in and begin
application coating the entire top
side of the board with an even
layer.
- Re-dipping the brush every 2-3
strokes is recommended.
- The board should look glossy
under lighting where coating has
been applied.
- If any safety concerns occur
consult the MSDS provided.
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Step 3: Detail Coating (chips in sockets)
- Coat the chips as well as long as
they are secured in their sockets.
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Step 3: Detail Coating (underneath components)
Apply
underneath
closely
oriented parts
like diodes,
capacitors,
and resistors
in this
manner.
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Step 4: Detail Coating (between components)
Apply
between
closely
oriented
parts
Use
smooth
strokes
(about 3
per dip)
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Step 5: Backside Coating
- Flip the board
over using
minimal contact
with the currently
curing coating.
- Coat the entire
backside as
desired using the
same 3 stroke per
dip rule.
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Step 5: Backside Coating
Apply across
the whole
board, make
sure the whole
PCB is coated
thoroughly.
Note glossy
look of
coated
board.
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Step 6: Touch-ups
- Visually inspect the board to ensure it
is coated thoroughly.
HV Section
- Make any touch-ups as necessary,
ensuring there are no bubbles
underneath parts.
- You may add additional coating to the
HV section if you desire, but one coat
is enough to do the job.
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Step 7: Drying and Clamping
- Flip the
board over
and attach
to helping
hands
where
shown.
- This area is
not HV and
won’t affect
the cure if
clamped
here
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Step 7: Drying and Clamping
- Allow the board to cure in a controlled environment for
24 hrs to achieve a full cure.
- Tack free cure is about 10 min. The coating wont stick
to your hand as readily after this stage.
- Handling cure is about 4-6 hrs depending on the
humidity.
- Cure time can be decreased by using a convection
heater at low heat (100 °F) and low humidity.
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