Building the tap tempo tremolo

[karter2000]

Just in the process of building one myself.  How about making my own opto?  I have a bunch of random LDRs, and my LED/LDR combo seemed to work great in my Trem Lune.  Is there a particular LED type to use?

[.Mike]

I used Futurlec # photocell1, and Mouser # 593-VAOL-5LAE2 (100mcd red diffused) when I built my pic trem, which is closely related to this. It worked really well.

It is my understanding most photocells respond best to yellow. One datasheet that I have (for the Tayda Cds photocells) specifies the peak spectral response as being between 550 and 650nm... yellow.

Mike

[EDLK]

Hey Taylor

I sent for a couple of new opto's from Steve Daniels.  I  put one in the on the board today.
I can knock out the tick if I crank the led to full on.  However the last bid of rotation on the led pot seems to take out a bit of my high's
I currently have a 2.2 cap in the 330 p position. Would lowering that cap value help with the loss of high's with the led cracked full on.
Does the led pot even affect the frequencies? Or am I getting a bit "blurry" trying to debug this tick?

Thanks Ed

[EDLK]

one other observation, it seems like most of the guys who have not had any issues with ticking have not used the external gain pot?
Could there be a connection between the ticking and the use of the external gain pot as apposed to the board mounted trim pot?

[Taylor]

one other observation, it seems like most of the guys who have not had any issues with ticking have not used the external gain pot?
Could there be a connection between the ticking and the use of the external gain pot as apposed to the board mounted trim pot?

Potentially - that pot is in the makeup gain stage's feedback loop. If those wires went over the LFO side of the board, or were right next to the LED wires, the LEd could couple into the audio path. The LED pot shouldn't really affect the frequency response.

[Taylor]

Also, wanted to let everybody know that Small Bear is now stocking the crystal needed for this project:

http://www.smallbearelec.com/Detail.bok?no=1128

[EDLK]

ok
I pulled the 25 K external pot and installed the trimmer pot
no change in the tick in the first 3 wave forms
In an earlier post you mentioned that we should not put the led trimmer pot to full on.  This is the only position where the tick is changed to more of a muffled pop.
I am going to try doing the onboard pots next.
Ed

[Taylor]

In an earlier post you mentioned that we should not put the led trimmer pot to full on. 

Did I say that? Doesn't sound right, but sometimes I do post here when I've just woken up or should be going to bed and my brain is not fully spun up.

I don't think you should put either LED trim all the way up. This will draw more current and I would expect this to mean more ticking.

[ORK]

Also, wanted to let everybody know that Small Bear is now stocking the crystal needed for this project:

Http://www.smallbearelec.com/Detail.bok?no=1128

Something seems to keep URL-hacking your Small Bear links.

[Taylor]

Uh, yeah, what the heck?

http://www.smallbearelec.com/Detail.bok?no=1128

Oh, I get it. The auto-parse code will add http:// to any url that starts with a capital letter. For some reason SB links start with a capital H in my browser.

[EDLK]

Ok
I believe I have attempted everything suggested on this forum to this point so I will not relist them
The last attempt was going with on board pots, i changed then all out.
I un twisted every other wire lead coming off the board and made them all as short possible.
Each and every attempt as yielded the same ticking in the first three wave forms

The only place where I can eliminate the ticking is with the LED pot full on, and this affects the high frequency tone.
Am I at the end of the line as far as suggestions go?
Thanks for hanging in with me on this
Ed

[jkokura]

Uh, yeah, what the heck?

http://www.smallbearelec.com/Detail.bok?no=1128

Oh, I get it. The auto-parse code will add http:// to any url that starts with a capital letter. For some reason SB links start with a capital H in my browser.

It's neat Taylor, Steve added in text that says "for Taylor Livingston's Tap Tempo Tremolo"

Jacob

[EDLK]

I just finished putting the circuit back into the enclosure after pulling it to de bug the tick
I tried on board pots, various cap sizes in the 330p position, swapped out the opto.
Tried the on board gain trim pot vs. off board 25K pot.
Rewired the every connection to be sure nothing crossed paths with the led or lfo signal carrying wires.
And now not only do I still have the ticking in the first three wave forms, I also have a buzz in the signal path.
Anyone have any Idea what I could have done to bring that on?
Not having sufficient electrical circuit knowledge, I believe I have reached my maximum debugging capabilities on this.
I would be happy now just to get rid of this new buzz which makes the pedal unplayable, and live with the ticking.

Any one willing to take this one on, I would greatly appreciate some help.
Ed

[Taylor]

Buzz usually means some grounding problem. Check that when you rewired things, you didn't fray the ground wires of the input and output jacks, etc.

[Barcode80]

Anyone else encountering problems getting the tap to work right? When I tap to set the tempo, it seems like the tempo is taking the tempo from the re-opening of the switch contact instead of closing. So I tap the switch, but the up swing of the tempo seems to be in between my taps, if that makes sense. When I use a tap tempo, I expect the signal to be at the top of the wave form for each tap, but it seems it is operating the opposite. Thoughts?

[Taylor]

What kind of switch are you using? You're sure it's a normally open type?

[Barcode80]

yep, normally open. i'm wondering about the debounce network, because also sometimes the tempo will jump up to about a million times faster than my tap when I'm tapping out the tempo. Which components on the board make up the debounce network?

[Taylor]

Debouncing is done in software. What sort of switch do you have?

[Barcode80]

This one
http://www.pedalpartsplus.com/mm5/merchant.mvc?Screen=PROD&Store_Code=PPP&Product_Code=9014&Category_Code=SWI

as far as i can tell it's the same one smallbear and mammoth sell. But I also tried swapping it with some known momentary NO switches I had, including some from an old MXR footboard and some push buttons from radio shack. Same result.

[Taylor]

Hmm, strange. That's the same type I'm using and haven't experienced that. As you can see in the schematic, the tap switch connects directly to the PIC, with just a resistor pull-up. So I can't think of any error in your build that could be causing it.

From TTG's page on debouncing, the simplest thing to try would be a cap across the switch terminals, but this probably won't help much. The logic debouncing is pretty simple and would do a much better job. That would be what I'd try.

Did you just build this up, or have you had this issue for a while? I only ask because I have built quite a few of these and only had that problem at first because it was my first tap tempo effect, and I didn't have the hang of tapping solidly. I don't in any way mean to impugn your tapping skillz, just wanted to mention that as a possible place to look if you hadn't yet. It might be a total non-issue, but just trying to help.