Download geiger counter schematic

High Voltage Generator for Flash and Geiger Tubes
Here is a 700 volt power supply for powering a Geiger tube or charging a capacitor in a flash unit. The
circuit uses a 1:1 telephone isolation transformer typically used in modems. The voltage is determined
by the string of devices including the neon bulbs. Select a combination of neon lamps, varistors or
zeners to achieve the desired voltage. Zeners are available at high voltages but neon lamps are probably
easier to obtain. The circuit shows the power supply in a typical Geiger counter circuit. Geiger tubes
draw about 100uA when they pulse but the pulses are very short and relatively far apart so the supply
need only source a few micro-amps to the output capacitor. Geiger tubes are available in a variety of
sizes and styles including units with thin mylar windows in the end for detecting larger particles
besides x-rays. This circuit is nice because it cuts back current consumption to less than 1 ma when the
load current is low. It works well from either 9 or 12 volts but it will supply more current with higher
supply voltages.
1 nf
+9volts
3, 1N4005
phone xformer
PRI
SEC
1 nf
10 k
700 volt Geiger Tube
1 meg
22 meg
1 nf
NE-2H
1N4005
22 k
120 k
NE-2H
MPS-A42
2N4403
220 k
Select a string of devices
to achieve 700 volts.
MOV or
Zener
3.3 k
2N4401
1 uf
Typical Geiger-counter circuit:
9 volts
5 volt beeper
4093
2N4401
10 meg
10k, sets sensitivity
5 nf
1 meg
M
1000 uf
100 ua