Hi
I had tried most of the simple interface designs and they did not work. Not to be discouraged, I decided to find out Why?.
On my desktop computer the current needed to pull pin 10 lo on the parallel port was 1.4 mA. Also the sink current from the FF9 was very low (I think its 1K to ground). Also with this transmitter the signal is high with pulses which go low.
The attached circuit works well and is cheap and simple to construct. I use it in conjunction with PPJoy and have found it to give excellent results. The hardest thing is making the FF9 connector which is based on 2mm spacing.
Hope someone finds this useful.
Best Regards
Martin R Dare
AAH! :0 I've just realised that you can't post images to this forum. If anyone can give me some assistance with this I'd be grateful.