Solenoid Issues

Forum 2005-2010 (read only) Hardware Interfacing
1

Seems solenoids are a popular thing lately. I'm a bit of a beginner on these things, so excuse me if I am doing something blatantly wrong! I've only come close to frying something, so I think that's good.

I've wired up my Solenoid according to the Solenoid schematic on the Arduino Playground (Arduino Playground - HomePage) however I don't seem to be getting any movement out of it.

The Solenoid is rated at 24V, but I'm using 9V to power it (appears to do the trick in my tests, just isn't very powerful). I'm not sure about the mA rating since I got it out of a scrap bin.

Using a TIP102, Rectifier Diode 1N4004, and several different ratings of resistors.
Photos are here: Solenoid Controller | Software portion of the controller on … | Flickr

  • Pin 1 of the transistor connects to one solenoid terminal. A rectifier diode is connected here.
  • The cathode side of the rectifier connects to the 9V+ and the other solenoid terminal.
  • Pin 2 of the transistor connects to a resistor (tried 3 ratings, and no resistor) then Digital Pin n on the Arduino
  • Pin 3 of the transistor connects to 9V Ground, and Arduino Ground

Is this correct? I'm at a loss here. I have no Oscilloscope to test this, just can't seem to figure out where the issue is. Any help would be much appreciated!

Thanks,
Brent

2

I don't see anything wrong there. Do you have a dmm or voltmeter? If you do you could test different parts of the circuit. For instance when you go from 0 to 5 volts on the base of the transistor (pin 2) the voltage drop from pin 1 to pin 3 should go from about 9 volts to about 0 volts.

3

Thanks for the quick reply! I'm not seeing any change in voltage from pin 1 to 3. I'm going to pick up a new transistor tomorrow and see if that's the issue. Is there any way to test if a transistor is working or not?

4

Here is a site that explains how to test transistors: Testing Transistors Tutorial and Circuits - How to test Transistor - Test and Measurements - Hobby Projects

If you get confused there are a lot of of sites explaining similar procedures if you type "how to test transistor" into google.

Good luck, and let us know when you get the circuit working :slight_smile:

5

Thanks for your help. I didn't burn out the transistor like I had thought, but I had the pins wrong. Pin 1 was the Base, 2 the collector, 3 the emitter. I had a bit of a head slapping moment at the store when I saw the schematic.

The one thing that gets me the most is how much this sounds like a heartbeat when its working! Again, your help is much appreciated.