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So I just finished building my Tap Tempo Tremolo and wanted to test it before I started installing everything in to the enclosure I have. I will post a picture of what I've got as soon as I can find some batteries for my camera (will find after I go out for a cigarette). But basically, I wired up the 3pdt switch as is showing in the diagram from the musicpcb.com site. The ground lines are as such...

-GND line from pcb to Line out ground (sleeve)
-Ground from 3pdt switch (as shown in diagram) to Line In ground (sleeve) then to 9V input ground (sleeve)
-LED isn't coming on.

When I turn on the pedal I get some buzzing intermittently and had some ticking (about 60bpm) that would eventually go away. The internal pots for the LED and octupler as well as the internal gain pot did nothing. No signal coming through whether the pedal is on or off. So basically, it doesn't work. I'll post a pic in a few minutes but I wanted to at least get these notes on here asap so I didn't forget anything. This is my first pedal build but I do have a few years of experience working on arcade and pinball pcbs so I know my soldering is good. Not always pretty... but good. There are no solder bridges anywhere or anything like that.

Here are some pics...

What's the voltages on the op amp like? The easiest way to troubleshoot is usually with an audio probe. (Which is just a patch cable cut up and a capacitor ~(100n) soldered to the input. Then plug it into your amp and follow the audio signal path.)

The ticking means the pic is probably working I could never make it stop for square wave for me.. but it is an awesome project.

Dunno... I'll look into building an audio probe today as I have plenty of spare patch cables.

Grab a multimeter, and check some voltages.

The 5v regulator should be putting out 5v, and that should feed PIC pin 1, and all of the pots except gain. PIC pin 5 should vary between 0 and 5v (it's the LFO output). PIC pin 4 and 8 should be at 5v. PIC pins 9-13 should be between 0 and 5v, and should vary when you turn the corresponding knob. If any this isn't correct, the LEDs might not work. If the LEDs don't work, the effect can not work, so double-check that you have both the indicator and the optocoupler oriented properly. Also check the orientation of the transistor.

For the audio portion, make sure the opamp has 9v on Pin 8, 4.5v on pins 3 and 5.

BTW-- do you have signal in bypass?

Mike

Mike... thanks. Those will be on my list for the next couple of days. And no, I didn't have any signal in bypass mode either. That is why I'm questioning whether I did something stupid like wire my in/out jacks wrong. Seems simple enough but it could be something totally simple like that that is screwing everything up.

When I build, I like to test as I go.

Before I connect the switching, I'll use alligator clips to test the circuit. If it doesn't work, I can be sure it's not the switches or jack wiring. Once the circuit is definitely working, jacks and switches can be added, and then tested again before boxing it up.

That way, you can be sure that you are debugging the right problem.

Mike

I use a 555 tone generator with the audio probe. way easier than trying to play guitar while you work.

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