Building the tap tempo tremolo

[tenwatt]

Doesn't this guy have a bypass and tempo LED?  Does this not work?

Here's a picture.  It has a light metalflake which makes the picture look splotchy.  It's actually pretty subtle.

[Taylor]

He must not be using the alternate bypass. It's not possible to have a flashing LED in bypass with the alternate bypass because it grounds the PWM signal so there's no varying voltage going to the optocoupler.

Have you actually built the pedal and had ticking issues, or are you planning this in advance? The alternate bypass is not necessary for most people.

[tenwatt]

He must not be using the alternate bypass. It's not possible to have a flashing LED in bypass with the alternate bypass because it grounds the PWM signal so there's no varying voltage going to the optocoupler.

Have you actually built the pedal and had ticking issues, or are you planning this in advance? The alternate bypass is not necessary for most people.

Planning in advace.  If it's not necessary for most I will try it without.

[lars-musik]

I have been unhappy with the absence of a pcb layout for a home-brewed Tap Tremolo for quite a while. So I decided to dive into pcb layouting with the very nice schematic by the electric druid (http://www.electricdruid.net/datasheets/TAPLFO2Datasheet.pdf) and came up with working solution (http://forum.musikding.de/vb/attachment.php?attachmentid=11757&d=1365895082).

My colleague Bastelfix in turn was unhappy with the size of the board and did a very good job (indeed, I'm impressed) in reducing the size and was even able to implement a hum-filter on the board.

So, for all the friends of etching, here's the final, single sided solution of the here discussed circuit:
http://forum.musikding.de/vb/attachment.php?attachmentid=11901&d=1368734215
http://forum.musikding.de/vb/attachment.php?attachmentid=11900&d=1368734198

You'll find the whole threat in the german Musikding forum: http://forum.musikding.de/vb/showthread.php?32683-Tap-Tempo-f%FCr-quot-Das-Tremolo-quot&p=346218#post346218

Best, Lars

[artifus]

I have been unhappy with the absence of a pcb layout for a home-brewed Tap Tremolo for quite a while. So I decided to dive into pcb layouting with the very nice schematic by the electric druid (http://www.electricdruid.net/datasheets/TAPLFO2Datasheet.pdf) and came up with working solution (http://forum.musikding.de/vb/attachment.php?attachmentid=11757&d=1365895082).

My colleague Bastelfix in turn was unhappy with the size of the board and did a very good job (indeed, I'm impressed) in reducing the size and was even able to imply a hum-filter on the board.

So, for all the friends of etching, here's the final, single sided solution of the here discussed circuit:
http://forum.musikding.de/vb/attachment.php?attachmentid=11901&d=1368734215
http://forum.musikding.de/vb/attachment.php?attachmentid=11900&d=1368734198

You'll find the whole threat in the german Musikding forum: http://forum.musikding.de/vb/showthread.php?32683-Tap-Tempo-f%FCr-quot-Das-Tremolo-quot&p=346218#post346218

Best, Lars

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[lars-musik]

Ah yes. Just register - its a forum for diy stompboxes. Nothing filthy about it. I'm pretty sure it's worth it.
However, here's my first (and large) try on the subject. Good for those with fat fingers and clumsy soldering irons.

http://www.freeimagehosting.net/rm912
People with smaller  fingers should try to register at the musikding forum in passing to gain access to the pdfs of Bastelfix.

[ThePastRecedes]

Hey there!

I've tried googling and that has not helped. How well does the VTL5C3 work? I've seen some comments on it but not any conformation on it. It's on the data sheet for the taplfo chip so I assume it works well....

I am currently using NSL-32 and there is some ticking. I'm going to change the transistor tomorrow and see if that does anything. The trim pots don't help much so I'm pretty sure its the vactrol. The VTL5C3 is the only other one I have around hence the question.

Thanks!

[Taylor]

The relevant parameters are the turn-on and turn off time. If you check the Perkin Elmer datasheet you can find the speed as compared to the NSL-32, but IIRC the 5c3 is kind of fast so might tick more. But worth a try since the tolerance on these things is so wide.

[ThePastRecedes]

I've tried the VTL5C3 and still ticking   I have the optocoupler section socketed b/c I thought I may have this problem. I placed a 220k resistor where the LDR half would sit so see if it was something else and there is still ticking. If my thinking is correct there should be no ticking with just a resistors there since the ticking is cased from the on/offf time of the LDR. Right?

[ThePastRecedes]

Also the ticking occurs when the pedal is bypass.

[Taylor]

Have you read this thread and tried te fixes herein? Changed the 330p cap? Done the alternate bypass? I know it's a lot to read but the answers are all here.

[ThePastRecedes]

Sorry I should have looked though this thread better

Next question... I tried serching for this one but the terms I'm using may be a little generic terms for using the search function 

Anyway... Everything works great but there is some ticking when on the square wave and the sawtooths. It that normal since that the wave has a dramatic change when it switches off?

Thanks!

[Taylor]

It's normal in the sense that it happens to a lot of people who build tremolos in general. If the trimpots haven't allowed you to trim out the ticking, try upping the 330p cap to a 1n-10n. Also make sure your wires, if any, are as short as possible and don't cross over each other unnecessarily. Sloppy wiring is often the biggest culprit.

[ThePastRecedes]

I've changed it to 1n I'm going to put a socket there and see what works best. Thanks again!

[roseblood11]

It's normal in the sense that it happens to a lot of people who build tremolos in general. If the trimpots haven't allowed you to trim out the ticking, try upping the 330p cap to a 1n-10n. Also make sure your wires, if any, are as short as possible and don't cross over each other unnecessarily. Sloppy wiring is often the biggest culprit.

Which wires exactly might cause these problems?

[Taylor]

If your audio in and out cross over the board, for example, they can pick up the digital signal capacitively.

[jeffersonmueller]

while waiting on new optocouplers to hopefully remove ticking, i tried lower-current LEDs per .Mike's suggestion (page 20 I think) and that significantly reduced the tick

I can even get "tick free" operation with the Output LED trimpot set "all the way up" - but aren't I without current-limiting protection for the LED at that setting?  It is a nice, very tolerable, brightness.

Secondly I've read elsewhere about using lower current op-amps to reduce ticking.  Has anyone tried swapping a tl-022 for the tl-072, for example?  I saw someone using one much earlier in the thread, but then he went silent . . .

I thought maybe my Volume knob wires were a culprit, but they made little difference in the ticking when moved around or even held straight above the board.

what did make a difference was when I moved the LED wires away from the power filtering.  I've since shielded them, and all inputs/outputs.  If I ever build another one I'll use the board mounted pots/LED configuration per the designer's intent.

Thanks for all the information in this thread!

[Taylor]

The trimpot probably doesn't get 100% to the end of its travel, so you likely have some series resistance still.

No personal experience with other opamps so I'll leave that for others.

[aryk]

Is there any way to make the LED's brighter? What is the CLR in the circuit? I'm assuming one of the 22k trimpots? If so which one acts as the CLR for the LED?

[Jonowinn]

I'm working on setting up the expression pedal to switch between the potentiometer and the onboard circuit contacts for controlling either the depth or the rate. The Catalinabread Semaphore has a toggle switch inside the pedal that switches the expression input between those two, so I know it's possible.

It occurs to me they may be using relay switching which is somewhat beyond my ken, at this moment. I've tried drafting up a couple of different ways to do it with mechanical switching, that I think would work, using 2 4PDT switches. the only problem being that I'm not sure it will work (still trying to finish figuring out the wiring,) and that having to use 2 switches is a royal pain/undesirable.

Has anyone else gotten this figured out, or know a better way to do it?

I can post diagrams tomorrow, to show more info. the gist of it is I drafted wiring the the grounds of all the jacks/pots/board contacts wired together, since ground is shared, and the 4 contacts on the switching jack connected to the middle rail of a 4pdt, and corresponding the tip and ring of the Depth pot and Depth board contacts on one throw, and the tip and ring of the Rate pot/board contacts on the other throw.

The issue with that being that while I can thusly switch the expression input between Depth and Rate, whichever one isn't selected on the 4PDT is disconnected from any potentiomer.

So I put another 4PDT to connect the potentiometers for rate and depth EITHER to the 4PDT that controls which parameter the expression input jack controls, or straight to the PCB pads. meaning if I select the expression input to control the Rate, I then can connect the Depth potentiometer directly to the Depth PCB connections.

tl;dr anyone have a tip on switching expression input control between two parameters?