low voltage with daqpad-6015 analog output

[PolymerTim3]

I am trying to actuate a solenoid micropump using a daqpad-6015.  The pump specs are 12 V, 4.0 W, and 0.32 amps.   While I realize that the 6015 only goes to 10V max, I find that a 9 volt battery can operate the pump.  Using a multimeter on the voltage output terminals, the reading is 10V before connecting the pump, but goes to 1V after wiring the pump.  Is there something I'm doing wrong, or is there some spec on the daqpad that can't handle this device?

[AlanArmstead]

You are probably just trying to draw too much current from the DAQPad.  It can source only 5mA of current from its analog outputs (See the E Series Help Manual).  You will probably need some amplification if you want to use the DAQPad.  Sorry 😞

-Alan A.

[PolymerTim3]

OK, I had a feeling it was something like that.  I hadn't been able to find the specs for the 6015, and I'm not very familiar with electronics.  Do you have any suggestions on a basic amplifier that would work in this case?  Probably I would just need something that plugs into a standard wall outlet and amplifies the 6015's signal.  It doesn't have to be very accurate, since the solenoid only detects 2 states, on and off.  I'm not sure what suppliers would sell something like this.

Thanks in advance for all your help.

[Ryan_V[DE]]

Tim,

Is the signal that switches the solenoid the same one that powers it? If this is the case, instead of using analog output to accomplish this, I would use one of the 6015's digital outputs connected to a solid-state relay (SSR). These signals are TTL compatible, meaning that they switch between 0 and 5 volts. They can source up to 13mA. This means that you'll need a relay which needs less than 5V, 13mA to switch states, but can control the 12V, .32A that your pump requires. I would search Digikey for a compatible SSR, and just use a 12V DC wall transformer (wall wart). You can also find those on Digikey. Please post back if you have any more questions.

Hope this helps,

[AnalogKid2DigitalMan]

You can also use a ULN2003 driver, you may need to use an inverter (SN7404) integrated circuit ahead of it to keep logic levels correct.

http://pdf.alldatasheet.co.kr/datasheet-pdf/view/25575/STMICROELECTRONICS/ULN2003.html

But the SSR is proabably the best way to go for you being the easiest to hook up. Plus it provides electrical isolation between your solenoid voltages and your computer.

In either case you should put a 1N4004 diode across your solenoid, with the striped end towards the + end of the power supply. This abosrbs the high voltage spike that is created when you turn off the solenoid. Without it, the spike can eventually damage the relay or driver circuits