Selfmade LPT Relay board
I have soldered 8 Way LPT RElay Board by myself from here:
it was very easey to do the board, but it did not worked. As I've read, LPT data pins give 5v when going active, but my M10K gives 3v, may that is the reason?
On a different "kit", the datasheet has this snippet, maybe it's useful to you? The circuit looks similar, but yours uses darlington array's (in the IC) instead of the transistors on the CK1601.
"Note that this analysis assumes 5V is available from the
parallel port pin. In more modern computers this may not
be so. If the LED turns on but the relay does not then you
will know that the transistor is not saturating. Reduce the
value of R1 (and all the similar resistors) to 2K7 from 3K3
will probably fix this. Measure the voltage on the collector.
When the relay is on then the voltage should be around
0.1V. If it is 3V - 4V then the transistor is not fully on."
Quoted from http://electronickits.com/kit/complete/elec/ck1601.pdf
Thanks Singh, probably this is the reason, that LPT output is less than 5v, as I cant give my IC 5v, I have to rebult the board then, on transistors, and tune voltage on base