Peak detector ground
« on: September 19, 2018, 07:33:48 PM »
I put 1/2 of a TL072 + 1 BC548c transistor to work as a audio peak detector on line level, after a NE5534 setup as a line receiver which unbalances.

Seems to work okay but probably doesn't catch the whole picture.  I read on this page http://sound.whsites.net/project30a.htm that his design was such that no dirty switching currents got into the signal ground and you should use a separate 0V reference for that.

What does he mean by that specifically?  Run a separate 0V bus from the power supply for the transistor that is blinking, or ...

I'm using the other half of the IC for some make up gain for my EQ.

Adam


ruffrecords

Re: Peak detector ground
« Reply #1 on: September 20, 2018, 04:04:45 AM »
The schematic as drawn does not separate LED currents. I think he means you need to provide a separate 0V connection back to the PSU for this circuit.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Re: Peak detector ground
« Reply #2 on: September 20, 2018, 01:28:15 PM »
Okay thanks, that's the only thing I could figure.  Guess I'll have to rig something up there to distribute yet another line to each card.

I think I'm going to set it to show peaks on the source level much earlier than 2.7V.. more likely to set it at 1 to 1.2V especially for the channel amps that I think like to see -4db on their input.

I like the idea of putting the indicator after an EQ (with make up) but before the channel output amp.  It's probably not crucial anyway, could probably come before the EQ but since you can boost a bit with it a little visual cue might not hurt as a reminder to turn the level back a bit.

Adam


 

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