Re: [CAD_CAM_EDM_DRO] Parallel port relay blues

Roy J. Tellason wrote:

>On Saturday 29 January 2005 09:30 pm, Alan Marconett wrote:
>
>
>>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.
>>
>>
>
>If it were a circuit configuration
>with say the inversion of the above arrangement, using a PNP transistor
>(2N2907 comes to mind as the opposite number of the 2N2222),
>

If you don't have a PNP you can also just use a second NPN as an
inverter, something like the circuit below should work.
(view in non-proportional font, or copy to notepad)

VCC
+
|
+------o
| |
.-. o_ +---------->
| | ) o
1k| | Relay ) / Relay Contact
'-' o_) o---------->
| |
| |
| |/
+----| 2N2222
| |>
| |
___ |/ |
In >--|___|--| 2N2222 |
1k |> |
| |
+------+
|
===
GND
(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)

Hope that helps
CS