Hi All
I built this voice modulator some time ago. It is built onto a PCB which I etched myself. Now because of the way the unit is used feedback can be an issue. Careful placement of speakers in relation to the mic's position is used as well as any acoustic padding to help reduce feedback as well. Also 'baffling' the rear of the mic helps and keeping the volume down is of course the other part of it.
Now as I learn little bits here and there I have seen mentioned that the gain can be adjusted by the use of a trimpot fitted into the the pre-amp of the circuit. The idea I have is to help further reduce pickup of the audio output which can cause the feedback and thereby maybe increase the usable range of my volume control.
So Having googled a bit and looked at data sheets I think I have Identified where a trimpot would go to facilitate the adjustment of the gain. I presume I would need to change the value of R4 downwards and the trimpot should exceed the current value of R4.
If I have got it right (added trimpot in series with R4) does a higher resistance increase or decrease the gain of the circuit? I attach a schematic of the circuit. I also understand I may have got it totally wrong and stand ready to be lined up against the wall and shot. :/
regards
Fenris
I built this voice modulator some time ago. It is built onto a PCB which I etched myself. Now because of the way the unit is used feedback can be an issue. Careful placement of speakers in relation to the mic's position is used as well as any acoustic padding to help reduce feedback as well. Also 'baffling' the rear of the mic helps and keeping the volume down is of course the other part of it.
Now as I learn little bits here and there I have seen mentioned that the gain can be adjusted by the use of a trimpot fitted into the the pre-amp of the circuit. The idea I have is to help further reduce pickup of the audio output which can cause the feedback and thereby maybe increase the usable range of my volume control.
So Having googled a bit and looked at data sheets I think I have Identified where a trimpot would go to facilitate the adjustment of the gain. I presume I would need to change the value of R4 downwards and the trimpot should exceed the current value of R4.
If I have got it right (added trimpot in series with R4) does a higher resistance increase or decrease the gain of the circuit? I attach a schematic of the circuit. I also understand I may have got it totally wrong and stand ready to be lined up against the wall and shot. :/
regards
Fenris
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