I have a solenoid with unknown specifications. I have contacted the manufacturer, but they are reluctant when it comes to sharing information about this product.

The problem

I need to trigger a solenoid from my Raspberry Pi. I want to do this by providing power from a DC power supply that came with the original product (The product is not the solenoid). I am using a Raspberry Pi as the control unit and a relay (http://www.songle.com/en/pdf/20084141716341001.pdf).

We also think that our solenoid is similar to this one: http://www.testco-inc.com/ledex-solenoids/B22-254-M-36

What we know

Before starting this project I have measured the Voltage and Current from the original control unit that shipped with the product. When we want to trigger the solenoid, the existing control unit sends 0,355 Amps at 22,1 Volts through the circuit.

I did make my own power cable using the DC power adapter and that provides 0,375 Amps at 24,1 Volts.

But the solenoid does not trigger

Does anyone have any ideas that I might try out?

Other questions

Could the voltage provided be too high? Does a solenoid requires more current to trigger, and then less to "keep holding?

  • \$\begingroup\$ You need to find a stack exchange site that is good at guesswork or clairvoyancy \$\endgroup\$
    – Andy aka
    Aug 20, 2016 at 9:27
  • \$\begingroup\$ They guy that answered after you seems to be good at that. He managed to draw up the schematics, AND provide a good workflow for me to troubleshoot. \$\endgroup\$
    – Stene
    Aug 20, 2016 at 12:07

1 Answer 1


You have not posted a schematic for your question so we can only give general advice on debugging your circuit.


simulate this circuit – Schematic created using CircuitLab

Figure 1. You should have wired the circuit up something similar to this.

enter image description here

Figure 2. You need to troubleshoot in a fashion similar to this.

Add a schematic to your question, do some basic troubleshooting and then modify your post to give the results of your investigation. Post a comment here to alert me to the update.


simulate this circuit

Figure 2. Where to take voltage readings.

If possible, create a program to turn the solenoid off and on every few seconds. Connect your multimeter on DC volts to 'B' and you should see the the voltage switch between 3.3 V and 0 V. Trace through the other points and record the values. Report back.

  • \$\begingroup\$ Thank you for your reply. I dont know how to draw schematics, but the one you provided reads like how this is all assembled. When you say measure voltage ON solenoid, what do you exactly mean? Measure it before, or after the solenoid? This here is what I have already done: I have tested the voltage from the power supply when the relay is triggered ON. The power supply gives 24,1 Volts, 0,375 Amps. But this is measured before the solenoid (I have disconnected the solenoid, and measured the voltage in the cable leading to it) \$\endgroup\$
    – Stene
    Aug 20, 2016 at 12:04
  • \$\begingroup\$ See the update. You need to check for voltage across the solenoid - i.e. at its terminals as shown in 'E' on the update. \$\endgroup\$
    – Transistor
    Aug 20, 2016 at 12:20

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