Download Pulsating pump circuit

Pulsating pump circuit
+24V
3Ω
100 Watt
resistor
2
+12V
0.01
25k
multi-turn
pot
100Ω
IRF640
1
7
8
4
3
1
3
3
39k
0V
6
2
Gorman-Rupp
Model 14825-710
19 VAC pump
NE555
2
CD4001
5
1
7
14
+12V
10
0.01
10
Capacitor values are in microfarads
Notes:
The pump requires a 24 volt DC power supply which can supply about 3 amps. The same power supply
can be used with a 7812 voltage regulator to provide a source of 12 volts to power the integrated circuits.
High power current supplies can be found at All Electronics http://www.allelectronics.com and also at
circuit specialists http://www.circuitspecialists.com
Any 555 timer chip can be used instead of the NE555. In particular, modern low-power versions of the
555 timer are OK.
Any power MOSFET that can handle 5 amps or more and 50 volts or more can be substituted for the IRF640.
I just happened to have lots of IRF640s lying around.
You can control the pump by setting pin 2 of the CD4001 NOR gate high (12 volts). When pin 2 is high,
the pump will be off. This is useful if you want to make patterns of drops via computer control.
Most Gorman-Rupp pumps sold on eBay are either 120 volt or 220 volt, but there are some lower voltage
models available. I purchased some 19 VAC pumps that work just fine with pulsed 24Volt DC. It probably
wouldn't hurt to place a power diode across the pump to prevent inductive kickback.
3 ohm power resistors are available on eBay for reasonable prices.
Multi-turn pots are useful for fine-tuning the pump rate (good for matching pump to strobe or camera frame rate).