Building the tap tempo tremolo

[slacker]

The waveform pot needs to be 10k because of the resistor in series with it, although you could use another value if you recalculated the resistor value. The other pots can be any value.

[Barcode80]

I just realized I only have 4 10KB pots, but my box is drilled to implement all five (including wave dist, no ext gain pot). I have lots of other linear pots (5k, 20K, etc) and I could do the parallel resistor thing, but that will make my pot act as a Log pot.

Can a 20KB or 50KB pot be subbed in anywhere? Otherwise, will a 10KB (makeshift) be usable for any of the controls?

It will be usable for all the controls, you just won't have the available range you have with the correct pots. So if you were supposed to use, say, a 100K pot, you could use a 10k but your range of available settings would only be what was supposed to be the first 1/10 of the dial.

[Taylor]

It will be usable for all the controls, you just won't have the available range you have with the correct pots. So if you were supposed to use, say, a 100K pot, you could use a 10k but your range of available settings would only be what was supposed to be the first 1/10 of the dial.

That would be true if the pots were wired as rheostats (variable resistors - 2 terminals) but in this case they are voltage dividers, so as slacker says, you can use other values for all but the multiplier pot (not the waveform pot) with no penalty at all. 50k is a fine sub - bigger values could theoretically become problematic as I don't remember how much current the pins expect.

[Beo]

That would be true if the pots were wired as rheostats (variable resistors - 2 terminals) but in this case they are voltage dividers, so as slacker says, you can use other values for all but the multiplier pot (not the waveform pot) with no penalty at all. 50k is a fine sub - bigger values could theoretically become problematic as I don't remember how much current the pins expect.

Crisis averted, I found some salvage 10kB pots from an old mixer I had. You're right that it doesn't matter. Looking at the schematic, most of the pots are straight voltage dividers varying 0-5v. Current feeding the chip would be reduced with a bigger pot, but probably wouldn't be an issue. Since it was spec'd for linear pots, I really didn't want to use a log pot if it would affect a useful control response.

[vassil]

Hi,

I want to build Wave form and Multiplier control with rotary switch.
Can anybody help me to mark voltage or resistance values for control steps:
Tnx



1 = xV, xR
2 = xV, xR
3 = xV, xR
4 = xV, xR
5 = xV, xR
6 = xV, xR
7 = xV, xR
8 = xV, xR



A = xV, xR
B = xV, xR
C = xV, xR
D = xV, xR
E = xV, xR
F = xV, xR

Tnx

[Vince_b]

Look at page 8 of this pdf:
http://www.electricdruid.net/datasheets/TAPLFO2Datasheet.pdf
This is what you need to know.

[Helloimjohn1234]

Hey guys, I'm new to the forum and this is my first somewhat successful build. I completed my Trem a couple of days ago and all functions work, with the exception of an unusual amount of humming, buzzing, and ticking. I've tried every trim pot combination possible, rewired the entire pedal with different combinations of routing methods, and reflowed most of the connections to ensure i wasn't getting cold joints. But the buzzing won't go away.... Anybody else had this problem??? The trem works, but the depth is really weak. The max value sounds like something I would expect around 40-50%. Any thoughts would be greatly appreciated!!!

[Taylor]

Check the wiper of your depth pot to make sure it sweep fully from 0v to 5v.

If it does, then the low depth will be because of how you have the trimpots set. You probably have the opto trimmed down too low and the gain up high to compensate - this limits the quietest it will get in the off position.

The buzzing is less obvious. What sort of power supply do you have? Are you powering anything else with it at the same time? Pickups? Are all your ground points correctly connecting to ground (in and out jacks, the board, the box itself)?

[Helloimjohn1234]

I don't have a meter at home right now so I can't check that just yet.. Could I be having ground issues because I'm using plastic neutrik jacks? I've tried a one spot, a voodoo lab pp2+, a battery and 2 different guitars. 1973 Les Paul deluxe and a custom shop tele. Same story all around..

Also, where is the best ground to tie the switch to (bottom left pin) ??

[Taylor]

Yes, if you have plastic jacks and no other way of connecting ground to your enclosure, then the box will not be doing its job of shielding. If you want to keep the plastic jacks you can scratch up the back of a pot and solder there to connect the box to ground. I recommend star grounding all grounds to the input jack sleeve.

[Helloimjohn1234]

Swapped out the plastic jacks for metal ones and that did the trick, other than a good bit of ticking, all features worked perfectly.. No combination of trim pots would make it go away..

30 minutes after this happened, I finished up another build and wanted to test them side by side. When I turn it on, all it does is buzzes and squeals really loud and won't pass any signal. So I've gone from perfect function to absolutely no function and I'm very confused. Could I be dealing with a bad opto??

[.Mike]

Buzzing... doesn't play well with others... a shot in the dark, but is there any chance you accidentally confused signal and ground at the jacks?

[Helloimjohn1234]

I considered it, but it worked solid for like 30 minutes (with ticking) and now it won't pass signal at all. And it's making some terrible sounds

[Taylor]

If you go back to just having the trem, does it act like it did before, or the same as when you have the two together?

[Helloimjohn1234]

It's all the same, tried different power supplies, guitars, and 2 different amps. No signal, just craziness. I'm really lost at this point..

[Lucas M]

hey everyone,
just have one question about the tap. i pretty much have it all good. i think i removed all ticking when its on, but when i have it bypassed you can hear the ticking. i have the circuit board output grounded when bypassed. should i do the same to the input? even if i have the lfo trim pot all the way down and the gain all the way down it still ticks. and the speed of the ticks are controlled by the tempo and multiplier pots. i didn't use the ultra bright blue led would that have something to do with it?
Anyway sorry to be a bother I'm just wondering why its making so much noise bypassed.
Thanks for your time,
Lucas

[Taylor]

I posted an alternate bypass diagram that will completely kill the LFO in bypass. I believe it should be somewhere around page 7 of this thread.

[Lucas M]

Thanks for the help Taylor.
Lucas

[Helloimjohn1234]

Last question, if I got the pedal back up and running but have a pretty significant tick regardless of trim pot settings, am I dealing with a bad opto?

Also, I'm still not getting the depth I was expecting but I don't have anything to compare it to. If I'm getting less than 5 volts on the pot could that be why?

Thanks again for your help!

[.Mike]

Last question, if I got the pedal back up and running but have a pretty significant tick regardless of trim pot settings, am I dealing with a bad opto?

Not enough information provided to make that determination. The best we could do with what we know is an educated guess.

Passing on what you did to get it running might help us to help you in the diagnosis process. Photos and/or a debug report would likely help us to help you in the diagnosis process.

And yeah, if there is less than 5v on the 5v side of any of the pots, you won't be able to get the full range of that pot. If your 5v regulator isn't putting out 5v, you won't get the full range of any of the pots, and it would likely cause issues with the PIC (can't put out 5v pulses if you don't have 5v to start), and maybe the LEDs, which would impact gain.

Mike