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N2CHX
09-06-2010, 11:04 AM
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.

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.


3266

N2CHX
09-06-2010, 11:07 AM
Double post. Not sure how it happened!

KG4CGC
09-06-2010, 11:09 AM
Cool set up. You're on a roll and just can't stop!
It's in your blood!

KG4CGC
09-06-2010, 11:10 AM
Double post. Not sure how it happened!
You were all excited and stuff about your solution and you just got an itchy trigger finger and it outsmarted the board software.

N2CHX
09-06-2010, 11:13 AM
Cool set up. You're on a roll and just can't stop!
It's in your blood!

I think it is. And yeah it feels good to do this stuff again.

KG4CGC
09-06-2010, 11:16 AM
I think it's neat how you were able to substitute components and explain why.

kf0rt
09-06-2010, 11:25 AM
Threads merged.

Cool vox. ;)

N2CHX
09-06-2010, 12:40 PM
Threads merged.

Cool vox. ;)

:) Thanks!

NQ6U
09-06-2010, 12:55 PM
You know a lot more about that stuff than I do, Kelli. I could have built the circuit from the schematic but no way I would have known enough about how it worked to make those substitutions. Nice job.