Fixed my PSK keying issue

[N2CHX]

I built a VOX circuit out of an LM324 op-amp and a 2N2222. Connect the input of the VOX circuit to the output of the sound card on the computer and ya got yourself a way to key the transmitter automatically even if you have no serial port to grab a status output from.

Here it is... Took me a couple of hours to build and test. Works very well.

Attachment 3265

It's basically this circuit but I modified it a bit. First, I'm using an LM324 instead of a 1458. I also added a 50k pot in the feedback loop in the first stage, to accommodate anything from mic to hot line level. I changed the 47 uF cap to 22 uF for faster response and changed the 33k resistors in the second stage balancing circuit to 10k for more control. ETA: Oh yes, and my ballast resistors in the first stage are also 10k instead of 47 and my input cap is a 1 uF electrolytic.


Attachment 3266