[HH] cheapest/simplest way to control a relay from a PC

[Tom Metro]

Mark Woodward wrote:
> Parallel port:
> http://www.linuxpcrobot.org/?q=node/5
> I've attached a schematic in pdf form.

Thanks.

For those who don't want to be bothered extracting the schematic, I'll
describe it. The parallel port D0 data output line source drives the
base of an NPN transistor, which in turn sinks current for a relay. A
few resistors are used to adjust the base current to the transistor, but
their values are left as an exercise for the reader.

Simple enough.

Have you used this circuit successfully?

 -Tom