Re: [CAD_CAM_EDM_DRO] Re: Parallel port relay blues

Hi Bert,

What is the voltage and coil current needed? You've got it connected
the way I was suggesting. Sounds like the transistor can't conduct hard
enough without a lot of base current. You might want to try a
darlington transistor (power). TIP120 comes to mind.

A 12V coil and 12V supply will require less current.

Alan KM6VV


bertmantx wrote:

>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Alan Marconett <KM6VV@a...>
> wrote:
>
>>Hi Bert,
>>
>>Are you tying one end of the relay to +5, and the collector to the
>
> other
>
>>end? The output gate of the parallel port is "sinking" current in
>
> this
>
>>case. More current is available then "sourceing" current.
>>
>>Alan KM6VV
>
>
> not sure what your trying to say, 5v PC power supply goes to coil
> then to collector, emitter goes to ground, base to para port. had to
> go down to 510ohm resistor to get 2222 to fire(took 8.2mA) using
> same 5v line. 2222 would not fire with higher restance. concerned
> about using lower ohm resistor to get para port to give up the 8.2mA
> needed to fire 2222.
> have diode across coil for suppression.
>
>>bertmantx wrote:
>>
>>
>>>Bought bread board today and went back to drawing board.
>>>I was able to get 2222 to fire but had to go to 510 ohm resistor
>>>(would not fire with any higher ohm resistor) at 8.2mA to base
>
> it
>
>>>will fire relay using 5v supply. When tried to fire with para
>
> port
>
>>>only drew 4.2mA and would not fire 2222.
>>>
>>>Any Ideas what the para port is capable of?
>>>
>>>Have been reading all the replies and would like to thank all
>
> for
>
>>>help.
>>>
>
>
>
>
>
>
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