Author Topic: Help - SL555F - Talkback module  (Read 4221 times)


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Help - SL555F - Talkback module
« on: September 24, 2021, 01:28:26 AM »
Hello friends,
I have an SL555F talkback module.

Does anyone know if this module has the circuit for the Listen Mic Compressor in it's signal flow?

Do you know where I can get a schematic or documents for it?

Thank you so much
Best regards



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    • Zevenaar, The Netherlands
Re: Help - SL555F - Talkback module
« Reply #1 on: September 24, 2021, 04:12:09 PM »

Yes, it has the listen mic compressor circuit (it's actually a FET-limiter). I'm not sure if I still have the schematics....

This is one of the simplest 5k modules. It doesn't need the -25v line either, only +18/0/-18v.
The only control that's included for the limitersection, is an onboard trimpot for the threshold. You can wire this one to a pot if you want to, you'll need a 10klin pot for it.

Oh, and in case you want a line input : set the internal jumper to external mic, and put a U-pad attenuator in front of the input (which is connected to the Jensen transformer).


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Re: Help - SL555F - Talkback module
« Reply #2 on: September 25, 2021, 09:17:16 AM »
Please find the schematic.