Building the tap tempo tremolo

[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?

Anyone know why I wouldnt be able to get the second LED to work?

[Taylor]

How exactly do you have the two LEDs hooked up? Are you using the standard bypass or the alternate bypass that was posted in this thread? There are a few ways it could be done depending on the behavior you want.

What I would do, if I wanted one status LED and one tempo LED, is connect an LED directly to the pos and neg LED pads on the board, skipping the switch altogether. That's your flashing LED that will always stay on. Then wire the bypass switch in the standard way to turn a separate LED on and off. That one won't flash but it will show bypass status.

[Ultrakd]

I mean Im wanting 2 leds that stay on all the time and blink. so a total of 3 leds...

[Taylor]

Ok so how did you try to do it that didn't work? The way to do that would be to just put another LED and series resistor between 9v and the transistor collector. Without knowing how you did it we can't know whether you just have a cold solder joint or if the way you tried is not going to work.

[Ultrakd]

I put 2 LEDs in the neg and pos place on the board that is for the LED

[Taylor]

Any time you have two LEDs in parallel, each one needs its own series resistor. Connect a resistor with one end to 9v, the other end to the positive lead of one of your LEDs, then the negative lead of that LED to the "neg" pad on the board.

[Ultrakd]

so let me see if i get it...they would still be in the same pads just they would both have resistors on them?

[sholm14]

Hello everyone. I'm new to the forum, but I've read everything and I'm very excited to get started with this project! I just ordered all the parts to make a few for some friends, but I had a couple questions I was hoping I could get answered before I get started.
The main question I have is about wiring a bypass LED. I understand that the tempo LED is just soldered onto the tabs on the pcb, and I've looked at the diagram from GGG for wiring a bypass LED, but I just don't understand how to incorporate this into the tremolo. Any detailed information on the wiring would be very helpful. Thanks!
Steve

[Radcon]

Debugging a freshly bult TTT.  I have checked voltages everywhere that should be 5 volts.  These instead read a bit more than 7 volts.  The 78l05 output is around 7 volts.  I hooked a fresh one up to the battery and got the same result.

Anyone seen this?

Any suggestions?

Other symptoms:
Bypass works
LED does not work
Audio path is good up to the optocoupler

Thanks for helping.

[Taylor]

What voltage do you read at your 9v input? Any chance you have a regulator with a different pinout than the 78L05?

[Radcon]

Input voltage from "9V" battery is about 10.2V.

I believe that it is a standard 78L05.  But I also tried it backwards, and got 9v out.  So I think I have it in the correct orientation. Three units from the same manufacturer exhibit the same behavior. 

Thanks

[.Mike]

Until you figure this out, you should remove the TapLFO from the socket (assuming you socketed it).

It has a maximum input voltage of 6.5V, and you risk damaging it if you give it more than that.

Once you figure out the regulator issue, you can put the TapLFO back and try again.

Mike

[Radcon]

Thanks for the help, folks.

Voltage problem solved by my Better Half who suggested that my meter was incorrect.  After exhausting all other possibilities, I replaced the battery in the DMM. 

Voltage out of the regulator now reads 4.96v.

[Taylor]

Are these still the symptoms?

symptoms:
Bypass works
LED does not work
Audio path is good up to the optocoupler

Possible explanations of which I can think:

Transistor could be in wrong - check pinout.
Optocoupler could be in wrong - check the first post of this thread
Bad solder joints in the area between the TAPLFO and the TL072?

[Radcon]

But alas, it still does not work.

Voltage readings as follows:

TAPFLO

1. 4.96
2. 0
3.  4.96
4. 4.91
5. 0
6. 0
7. 0
8. 4.96
9. 1.65
10. 3.62
11. 1.24
12. 1.16
13. 2.59
14. 0 ground

TL072

1. 6.37
2.  6.37
3. 6.07
4 0 ground
5. 6.08
6. 6.37
7. 6.37
8. 12.78

Q1

E 0 ground
B 0
C 2.53

Vin 12.89
All pots at approximately 50%

I believe that I have the opto in correctly.  Investigating the transistor pinout.

Thanks for the help. 

Do these readings shed any light?

[ElectricDruid]

Hi there,

The readings look pretty good. Pin 9 should be 2.5V, but that won't stop it working -it only sets the wave distortion. The other pots don't look like 50% always - you've got 1 or 1.5V not 2.5V, but again, this won't stop it working.
Instead, I'd look closely at the crystal and the two caps on pins 2 and 3. If the clock isn't running, the chip is dead. If it is running, you should see a 19.5KHz pulse train on pin 5, the PWM output. If you've got no oscilloscope, run this pin through a flip-flop or divider/counter chip and listen to the output  as audio. You'll hear it if it's running. 19.5KHz is too high for my hearing to be sure, so the dividers help.

Tom

[.Mike]

You could also test the LEDs by jumpering across the transistor, C to E. The LED should light up. If it doesn't, then the LED and/or optocoupler could be backwards and/or dead, or there could be a problem with the trimpots.

If the LEDs work, you can test the transistor by manually feeding the base a voltage through a 10k resistor (which is what the TapLFO does). If the LEDs don't work, the problem could be with the transistor.

Mike

[Radcon]

Thanks for the help, everyone.  I am back from a camping trip and returned to the Project.

1.  I believe that I had the transistor in backwards.  Fixed that, but it still does not work. 

2. Unfortunately, I am unable to test the clock as suggested. 

3.  Both jumping C to E and connecting voltage to the base through a 10k resistor cause the LED to light and signal to pass through.  I take this to mean that the transistor, opto, and LED are all now oriented correctly.

I now believe that I have a dead TAPLFO chip.  Any opinions to the contrary?

Thank you

[engineelite]

So I'm reporting back after trying out different photocells and the NSL-32sr3 solved my depth problem completely and didn't add any ticking BUT when the signal flows through it  there is slight buzz/hum that comes in and out with the pulse of the trem. while playing the buzz isn't very noticeable but without playing its very noticeable. any ideas to fix that issue. If I can get that buzz out then it'll be perfect!

Thanks.

I suspect the buzz/hum is just the noise in the system being amplified and switched through the tremolo. Try shorting the input to ground and see if you still have the buzz/hum on the output.

I finally got around to working on my trem again. I shorted the input to ground with all different values of resistors from 1k to 1m and it definitely got alot quieter but there is a tick/buzz still in the background when I'm not playing. Any other suggestions? Thanks.

[roseblood11]

Maybe someone could post his labeling for the waveform pot?
Would be really helpful... Maybe this could even be included in the project pdf?