Building the tap tempo tremolo

[karter2000]

Having a strange issue.  When I completed the tremolo, I tested it on a breadboard and it was dead quiet with no ticking.  Now that it's in an enclosure, I'm getting significant ticking on some waveforms.  The annoying thing is that it's doing it even in bypass.  I've tried redoing my wiring as well as disconnecting the LED but nothing changes.  Anyone have the same issue?

[Taylor]

Check out the first four pages of this thread for a lot of relevant info and a diagram.

[karter2000]

Thanks Taylor, totally missed that.  

[karter2000]

Well, I used the correct wiring scheme and messed around with the trimpots some more.  I believe I have the tick completely dialed out, plus it has lots of gain.

[Taylor]

Cool, glad to hear it. It can be tricky to dial in, but it's quite possible to build this with no ticking. I spent a lot of extra time with this PCB layout, doing overkill measures to keep grounds separate and all that for that reason.

[wizardsofzen]

is this board http://musicpcb.com/pcbs/tap-tempo-tremolo/ - capable of being the modular LFO Synth? - http://www.electricdruid.net/datasheets/TAPLFO2Datasheet.pdf

need to get 1 or 2 of this one with my 2 echo base when i order soon... thanks!

[.Mike]

is this board http://musicpcb.com/pcbs/tap-tempo-tremolo/ - capable of being the modular LFO Synth? - http://www.electricdruid.net/datasheets/TAPLFO2Datasheet.pdf

I would have to say no, not directly.

This project uses the interaction between an LED and a (slow) LDR to filter the LFO, and uses the LDR to vary the gain of an opamp.

The modular synth LFO from the datasheet uses a series of filters and amplifiers (and a bipolar power supply) to output a clean +/-5V LFO.

You would have to build everything that is connected to pin 5 on a separate board, including the power supply that is not shown.

Mike

[wizardsofzen]

thanks for that! time to perfboard then

[spargo]

So, I built a TTT months ago and have been using it regularly.  But the other day, all of the sudden the LED started going bonkers.  It blinks supper fast for about a second, then off for a second, then repeats - kind of like the lights on a cop car.  It doesn't seem to be very related to the current speed/waveform.  The trem itself still seems to work fine though.  Any ideas?

[Taylor]

Honestly, I can't figure out what could possibly be happening there. You're saying that it flashes the same no matter what speed and waveform you set?

[.Mike]

The indicator LED and the LED half of the of the optocoupler are both driven by the same transistor. So, since the tremolo is working fine, you can deduce that the transistor is driving the optocoupler as expected, and so the transistor is probably working fine.

The problem most likely has to lie somewhere after the transistor. Maybe the LED somehow got fried, or there is an intermittent solder joint.

Mike

[spargo]

Honestly, I can't figure out what could possibly be happening there. You're saying that it flashes the same no matter what speed and waveform you set?

Mostly yes...there may be a very slight change in how long/short if pauses for, but in general it's the quick flashes, pause, then more quick flashes no matter what the settings are.  I will take another look at it and see what I can find.

[spargo]

Anybody have luck with ticking on this build?

I've adjusted the trim pots to kingdom come, but still have ticking both when the pedal is engaged AND in bypass...  I have wired a regular bypass LED in addition to an always-on rate LED.  Even if I turn the LED's trim pot so far down that the LED is off I get the ticking.  The opto's trim pot is also all the way down and I can still hear it.

[.Mike]

It's definitely possible to tune out any ticking, which should be minimal anyway.

What type of opto you are using, have you tried a different one in its place, and what type of LEDs you are using for indication?

Check the areas that handle power filtering to make sure you don't have any cold solder joints. Try increasing C9 to 1n.



Mike

[spargo]

It's definitely possible to tune out any ticking, which should be minimal anyway.

What type of opto you are using, have you tried a different one in its place, and what type of LEDs you are using for indication?

Check the areas that handle power filtering to make sure you don't have any cold solder joints. Try increasing C9 to 1n.



Mike

I'm using the Silonex NSL-32 from Smallbear, and uh...regular LED's?  Your standard 5mm.  On regular LED for bypass and one connected to the board for indication.  Soldering is fine.  I've tried increasing C9 to 2.2uF and I *think* it helped a bit when the pedal was on, but with the pedal off the ticking was just as bad.

[.Mike]

The reason I asked about the LED is because standard LEDs use a lot more current for the same brightness. For example, the standard LEDs I bought in bulk from Tayda take the full 20 mA to equal the brightness that I achieve on a quality non-superbright red LED at about 2 mA. If you have two or three LEDs running at 10-15 mA each, and you add in the ~20mA the PIC takes (IIRC from when I was hacking together the non-tap version of this), you could be trying to pull 65 mA through that poor little 78L05 regulator. The more current you pull, the higher the chance of noise.

Of course, since it still ticks when the LED current is very low, and since it is ticking when it is bypassed, that suggests there is error in your build. There haven't been many reports of people with that problem that I remember, but you may want to go back and see if someone else had (and fixed) the same problem. Also, the audio path to this is the same as the Trem Lune, so a lot of the debugging information that is out there applies to this as well.

Mike

[spargo]

The reason I asked about the LED is because standard LEDs use a lot more current for the same brightness. For example, the standard LEDs I bought in bulk from Tayda take the full 20 mA to equal the brightness that I achieve on a quality non-superbright red LED at about 2 mA. If you have two or three LEDs running at 10-15 mA each, and you add in the ~20mA the PIC takes (IIRC from when I was hacking together the non-tap version of this), you could be trying to pull 65 mA through that poor little 78L05 regulator. The more current you pull, the higher the chance of noise.

Of course, since it still ticks when the LED current is very low, and since it is ticking when it is bypassed, that suggests there is error in your build. There haven't been many reports of people with that problem that I remember, but you may want to go back and see if someone else had (and fixed) the same problem. Also, the audio path to this is the same as the Trem Lune, so a lot of the debugging information that is out there applies to this as well.

Mike

Can I ask where you get "high quality" LEDs that get the same brightness for 10 times less current?  I'm using ~5-8000mcd LEDs.  And thanks for the trem lune info, will look into it...

I should also note my waveform LED is coming off the board and thus through the LM78L05 regulator, but the second bypass LED is running straight from the 9V source.

[.Mike]

Well, the difference I was pointing out is between "standard" LEDs, which datasheets indicate put out single-digit MCD levels, compared to, for example, one like this, which is not high efficiency or high brightness (100mcd), but certainly puts out the same amount of light at 2mA as a standard LED.

That's the LED I used in my build for indication and for the optocoupler. When I was debugging, switching from LEDs out of the bulk bag of standards to LEDs that were more efficient, and upping the cap I mentioned earlier, completely eliminated the ticking I experienced. I attributed that to the fact that I was able to measure the same resistance from the photocell with less than a fifth the amount of current. I went from using something like 30mA of current for the two LEDs to something closer to 5mA, a huge difference.

Maybe Taylor can chime in if he remembers from when he was designing this, but if upping that capacitor from 330p to 2.2u didn't stop the ticking, it would again suggest a mistake in your build. Most people, it seems, settle on 1n in that position.

Mike

[spargo]

I'm working on a TTT at the moment, and my tap switch did not appear to be working.  On further investigation, I found that ultimately my 78L05 is getting an input of roughly 8.8v and sending that same 8.8v right out the other side.  Would it appear this one is faulty?  Oddly enough, the trem works fine, minus the tap switch.

Disregard...it seems that somehow either Eagle flipped the part the wrong way or I got 78L05's with a reversed pinout.  The Fairchild Semi ones I got ended up being put in backwards...

[Jamforthelamb]

I just found this project while I was eyeing the Meatsphere project over at Musicpcb, and I don't think I can express how stoked I am to build this!

Short history (and partial reason why). I've been a guitar player at churches for over 10 years now (geez has it been that long?!?!), and one thing you'll find at a lot of churches is that they like to keep the guitar player "under wraps" using direct in type effects such as the Line 6 pod setup. So, I had one, and while I found most of it's modulation and time based effects AWESOME, there was a serious lack in tone (especially distortions) YMMV tone is subjective, not a debate against Multieffects. Fast forward a couple years, playing at different church with a sound guy/worship pastor who is all about tone. I'm now playing with a tube amp/pedalboard mic'd etc etc. The only downside is I've never been able to find a tremolo that was as versatile as the one on my Pod XT in stompbox forum. I have Line 6's Tap Tremolo pedal now, which works OK, but it doesn't have any kind of Time Signature/Multiplier feature, or near the options that this project has.

Needless to say I will be building this project, and putting the Line 6 pedal up on the 'bay. That is, once I get my workstation a bit more "clear" 

Hope this post isn't too far off track. Just wanted to give kudos to the builders/designers/contributors of this project from a guy that will get a lot of real world use out of it 

God bless,
-Kevin