Re: [CAD_CAM_EDM_DRO] Re: Getting Parallel port to run relay

bertmantx wrote:

>[snip]
>
>
>Shouldn't the circuit have fired with 5v power source going directly
>to Base? Or does it have to be current reduced with resistor?
>
>

If you attach a high current supply directly to the base of a
transistor, you'll fry the transistor. The effective circuit between
the base and emitter of a transistor is just a diode, so connecting V+
-> base ---- emitter -> ground is a bad thing.

You can use anything between a 1K to a 5K resistor, depending on the
required relay current.

- Steve