On Thu, 14 Aug 2003 00:05:12 +1000
"Peter " <email@example.com> wrote:
> I've connected the 5v+ pin of my parallel port to the 4.7k resistor. (It doesn't matter which direction the resistor goes does it?) I've then connected the resistor to the base pin (B) of my transistor (an NPN 2N2222A). I've connected the ground pin of my parallel port to the emitter pin (E) of my transistor. This is as much as I've built for now as I'm not even getting a signal from my transistor! (The signal from my transistor is supposed to trigger the relay.)
It does not matter which way the resistor goes.
The diode in the circuit is to stop the voltage spikes that occur when the relay opens. (>1000volts)
So if there is no relay present, there will be no voltage/current path on the transistor collector. Therefore nothing will work.
Why not try a resistor instead of a relay, say 470 ohms. That way you can measure the collector voltage and see if it is working.
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