Building the tap tempo tremolo

[.Mike]

I mean could there be a situation where some "new" settings will be ignored when switching from one pot set to another?

The way the TapLFO works is via a control voltage. Each setting-- tempo, waveform, etc-- is set based on a voltage being fed into the TapLFO chip. Voltage goes into chip, software within chip evaluates voltage, software within chip alters LFO based on the voltage.

If a voltage between 0 and 5V is sent to the TapLFO, the settings WILL be picked up. If the settings were not picked picked up by the TapLFO, then the TapLFO would be malfunctioning.

You can feed the TapLFO voltages created by potentiometers, fixed resistors, or even another LFO (as long as it is between 0 and 5V).



Mike

[Valoosj]

I recently had the problem that my tempo footswitch no longer functioned. I can tap the tempo, it works for 3 cycles and then it goes back to the pot setting.
Any idea what could cause this? The trem worked fine before. Only thing I know that could have triggered it is a short circuit I had due to a daisy chain outlet touching ground.

Should I reprogram my IC?

[.Mike]

Should I reprogram my IC?

I can't imagine that reprogramming the IC would do anything to fix the problem. I suppose corruption is possible, but unlikely. Maybe you got hit by the solar flare a couple weeks back.

I would suspect everything connected to pin 13, the Rate CV.

If, for example, there is an intermittent connection to the pot that causes the voltage being sent to the TapLFO pin 13 to vary more than whatever tolerance is built in to the software, it would kick out of tap tempo mode, and back into regular mode.

Stick a multimeter on the pin 13. Tap in a tempo. Move the wires around. Check for variance. It should remain stable, and any change will kick it out of tap tempo mode.

The only other thing I can come up with is that maybe the 5V output is not stable. The 5V regulator feeds the rate pot. If that 5v varies up and down, then the voltage sent from the rate pot to pin 13 would also vary, kicking it out of tap tempo mode.

That's where I'd start.

Mike

[mpv]

I mean could there be a situation where some "new" settings will be ignored when switching from one pot set to another?

The way the TapLFO works is via a control voltage. Each setting-- tempo, waveform, etc-- is set based on a voltage being fed into the TapLFO chip. Voltage goes into chip, software within chip evaluates voltage, software within chip alters LFO based on the voltage.

If a voltage between 0 and 5V is sent to the TapLFO, the settings WILL be picked up. If the settings were not picked picked up by the TapLFO, then the TapLFO would be malfunctioning.

You can feed the TapLFO voltages created by potentiometers, fixed resistors, or even another LFO (as long as it is between 0 and 5V).



Mike

Thanks Mike.

Your answer clarified that using switchable pots/trimmers/resistors would work for presets.

Now I just have to find a suitable enclosure in case I choose that the preset trimpots should be externally adjustable through small holes...
I was thinking that 1590BB would be the maximum size for this but now it seems that I need a bigger box...will have to measure the required space for parts again...probably will do a couple of cardboard models of Hammond boxes...

MPV

[fatecasino]

If the signal and ground of your audio out jack are connected, there most likely is a wiring error that needs to be corrected.

Mike you are guru!!
thank you very much for your help, it seemed that the (+)ear of the input jack was touching the back of a pot ( creating a circuit
Now it's back to life

My only problem is that in bypass mode I get ticking when in square mode. I followed the advice of page 3 but nothing. I tried all possible combinations of the trim pots and I still have the ticking. Actually turning the trim pots doesn't seem to have any effect on ticking while in bypass mode. Is that  a hint for something?

[Johnny B]

My only problem is that in bypass mode I get ticking when in square mode. I followed the advice of page 3 but nothing. I tried all possible combinations of the trim pots and I still have the ticking. Actually turning the trim pots doesn't seem to have any effect on ticking while in bypass mode. Is that  a hint for something?

If you have wired the switch as per Taylor's diagram on page 3 (top of R1 shorted to ground through switch when in bypass) then you cannot have ticking in bypass mode. If you have then you must have a wiring error. The ticking is caused by the current surge when switching the LED side of the optocoupler. With pin 5 of the uP shorted via a 10k resistor to ground with the above switching arrangement in bypass mode, then the opto is not switched, so no ticking.

[monkeyssj1]

Hey guys, I accidentally broke my tap lfo chip .... anyone know where I could purchase another one?

[Taylor]

Send me an email at info [at] musicpcb.com and I can set you up with another TAPLFO.

[.Mike]

Nice! What kind of finish is that? From a distance, it almost looks like a terrazzo floor, but up close, it looks like a flower pattern. Hmm.

[monkeyssj1]

email sent

[fatecasino]

Nice! What kind of finish is that? From a distance, it almost looks like a terrazzo floor, but up close, it looks like a flower pattern. Hmm.

it's a flower pattern 

[Valoosj]

Should I reprogram my IC?

I can't imagine that reprogramming the IC would do anything to fix the problem. I suppose corruption is possible, but unlikely. Maybe you got hit by the solar flare a couple weeks back.

I would suspect everything connected to pin 13, the Rate CV.

If, for example, there is an intermittent connection to the pot that causes the voltage being sent to the TapLFO pin 13 to vary more than whatever tolerance is built in to the software, it would kick out of tap tempo mode, and back into regular mode.

Stick a multimeter on the pin 13. Tap in a tempo. Move the wires around. Check for variance. It should remain stable, and any change will kick it out of tap tempo mode.

The only other thing I can come up with is that maybe the 5V output is not stable. The 5V regulator feeds the rate pot. If that 5v varies up and down, then the voltage sent from the rate pot to pin 13 would also vary, kicking it out of tap tempo mode.

That's where I'd start.

Mike

Thanks, my 7805 being dead/faulty seems highly plausible. I did think that a 1N4001 at the 9V input would protect the other electronics from a short circuit. (in this case my 9V of the daisy chain touched ground somewhere)

[fatecasino]

If you have wired the switch as per Taylor's diagram on page 3 (top of R1 shorted to ground through switch when in bypass) then you cannot have ticking in bypass mode. If you have then you must have a wiring error. The ticking is caused by the current surge when switching the LED side of the optocoupler. With pin 5 of the uP shorted via a 10k resistor to ground with the above switching arrangement in bypass mode, then the opto is not switched, so no ticking

.

The solution is the alternative wiring of the diagram in page 3!
I thought the diagram on page 3 was about a second led.
This should definitely be in main pdf of the tap tremolo

[Johnny B]

If you have wired the switch as per Taylor's diagram on page 3 (top of R1 shorted to ground through switch when in bypass) then you cannot have ticking in bypass mode. If you have then you must have a wiring error. The ticking is caused by the current surge when switching the LED side of the optocoupler. With pin 5 of the uP shorted via a 10k resistor to ground with the above switching arrangement in bypass mode, then the opto is not switched, so no ticking

.

The solution is the alternative wiring of the diagram in page 3!
I thought the diagram on page 3 was about a second led.
This should definitely be in main pdf of the tap tremolo

Glad the alternative wiring solved the problem in bypass mode. Taylor did say in this thread page 29 on March 19 "The next time I'm at my other computer, I will add the alternate wiring to the build document and add it to the musicpcb website." Guess he just hasn't had time yet.

[fatecasino]

I really can't stop playing with the tremolo
After so much I have 2 quick questions:
1. What does wave distort.  really do? I can hear a slight change in the sound, but I don't really understand what it does
2. The tap does not always work..I cannot get the exact tempo I tap. When I tap I can hear some scratch sound coming from the switch. SHould I try to change it?Or do I have some wiring/leak problem?
Thanks!

[.Mike]

1. What does wave distort.  really do? I can hear a slight change in the sound, but I don't really understand what it does

It should be very noticeable, especially with the square wave.

Have a look at these images to see if it helps:

http://www.electricdruid.net/images/lfo/PDDiagramV9C.gif

http://imageshack.us/photo/my-images/199/wavedistortnoise.jpg


Not sure on your switch question, sorry.

Mike

[Ultrakd]

I Wanted to add a second LED to stay on and blink but it didn't work. Only one LED would blink and the other wouldn't come one. Suggestions?

[pedaljunkie]

Hey guys, I finished my build on this really great sounding trem.  Great job on this one to everyone who contributed.. especially you Taylor!   

I have a quick question tho.  I, like others, can dial out just about all of the ticking and it only seems to happen in square wave mode.  (I can wipe it ,but the LEDs are way too bright if I do that)  I am going to try the 100uf cap across 9v to ground tonight.

QUESTION IS THIS:  (forgive my lack of knowledge...  I am assuming a 100uf electrolytic cap is what I should use)  would I connect the positive lead of the electrolytic cap to 9v and the negative lead of the cap to ground? this makes sense to me, but figured I'd ask before proving myself stupid!   

Thanks!

[Taylor]

Cool build!

There is already a 100uf from 9v to ground on the board. I suppose another could help, but I don't expect this to make a huge difference. Have you changed the 330p cap to a 1n?

[pedaljunkie]

Thanks for the heads up, Taylor.  As I perused it tonight I figured that out, but will try replacing the 330pf with a 1nf cap.  This thing sounds awesome!