A few questions and trouble shooting

[Detrital]

Hi,

I'm Detrital, new here but not to building pedals.
If I've posted in the wrong spot - Sorry. Please bump me to where I should be...

I've got a few builds that are giving me trouble. Any help is appreciated.

ElectroVibe - No build docs yet, but the silkscreen is mostly complete. I need to know TO-92 what goes above the 47R and LT1054. Suspect it's a 78Lxx of some sort as the middle pin connects to ground. Also what LED is recommended for the opto. Looks like it could be a bi-colour from the orientation of the flat side?? or will a diffused 5mm red/orange/yellow work well here?

HAARP - Build works as it should but the wet output is very noisy. No noise when it's off or from the dry signal path. I'm testing on battery so there is no PSU noise. Have tried adding a few 104 MLCC caps to the rails and Vref and no improvement. Also a 100pF in parallel with the 2n2. Possibly a dodgy FV-1 ???

Low Tide Modulator - It just sounds a bit off. I mean all of the controls work but it doesn't sound like any of the demo's. I think I might have got a fake MN3207 as there is no real delay component to the sound. The modulation seems to only effect the filter (low pass gate). If I turn up the LPG it starts to distort too. I've got a V3207D on the way to test with and see if it sounds any better.

Cheers - Detrital

 

[Detrital]

Thank you for the reply. I got it working last night thru trial and error adjustment of the trimpots.

Many thanks for the schematic link too, much appreciated.

My PCB does not match the layout in the build doc you posted, the trimmers are in a different position, the LM13700 has been flipped upright as well as a few other changes.

 

[PJS]

Have you got an audio probe? Have a listen to the inputs and outputs of the FV-1. If there's noise in the inputs it will be there in the outputs.

 

[Detrital]

I do have an audio probe. Inputs to the FV-1 are clean and perfect. There is no noise in the dry signal path either. Only noise on the FV-1 ouput and "wet" portion of the circuit.
I tried a 10k connected to the output filter as per the datasheet, and it did reduce the noise slightly, but it also made the signal very muddy and dull.