Electronic – Is a C2328 Transistor OK to use instead of a 2N2222


I have this simple circuit to drive a 5v solenoid. I made it all except that Q1 is a C2328A transistor I pulled out of an old power supply and C2 is a 220uF cap. D1 is just a diode I took out from another power supply, not sure what it is.

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Basically the solenoid rings a bell. THis worked for about 2 weeks but now it will ring once (2 rings) then the next time only 1 ring and its dead. The solenoid will just not move anymore though the program is running and is triggering the transistor.

It works of USB power and is triggered by RTS using a USB to SERIAL dongle. The COM port stays reactive.

I wonder if this circuit is flawed and possibly caused damage to the cap or the transistor?

Best Answer

I assume your magnet does not draw a large current, let's say up to 200mA or so.

Q1 can be replaced by almost any transistor, the one you mention should do fine.

The effect that you describe could well be cause by D1 not working (failed open). The high-voltage pulse caused by switching the relay off would not be dissipated by D1 but instead destroy Q1.