Building the tap tempo tremolo

[dawnofzion]

Finally finished this.
Here's a picture...

[Taylor]

Cool, is that Niko?

[tuffrabit]

K, noob questions time.

Should there be or not be continuity between the tip of one jack and the sleeve of the other jack (or general ground)?  I'm guessing there should not be... but there is.  So I've got a short somewhere?

[tuffrabit]

Figured it out.  The output jack tip was just barely touching one of the pot housings.

[dawnofzion]

Cool, is that Niko?

It's not Niko, but it is from GTA V.

[1878]

Los Santos Customs

[tuffrabit]

Yay!  It's mostly working now.  I got rid of the ticking by using an old guitar lead for shielded lines for the input and output jacks.  Now it does this thing where it will be fine for a time, then it will pop loudly then loose 40 - 50% of it's volume and take on this scratchy squealy quality.  Going to bypass and then back on "fixes" it for a time.  I have a theory that maybe the PCB is moving on the inside of the enclosure and touching stuff it shouldn't, but that may or may not be the issue.  I made a video of this happening (I just now uploaded it, so it might still be processing):

[acehobojoe]

based on what you said, It is incredibly likely that the pcb is wobblin' around in there. Try to secure it.

I've been in the process today of making a new PCB for the TTT to allow for our rotary needs. I also wanted to cut out the time it takes to hand wire pots and just have a PCB with mounted pots.

Here's the schem I have so far with two rotarys. Sorry for the sloppiness, it's a first draft. Any revisions seen here are appreciated.

http://i.imgur.com/IRDCNQA.png

[lulu_joe13]

Fun build. I was careful and I didn't have to do much trouble shooting! I hung the TapLFO LFO circuit off mine to use with my Moog stuff.
http://www.radioles.com/works/tttlfo1.jpg
http://www.radioles.com/works/tttlfo2.jpg
Thanks for the great project and all the help from Tom Wilshire, too. Joe.

[Andrew B. Campbell]

There are a few questions I would like to ask you regarding the tap tempo tremolo build as far as modifications are concerned. Being the type of person that I am, I enjoy being able to apply as much to the pedal as possible for as much versatility with the least amount of unwanted noise as a result:

1) Expression pedal input - I would like the ability to apply an expression pedal input to the build that monitors both the optional Rate and Depth of the LFO. I'm aware that what I would have to do is apply an On-On toggle switch somewhere within this, but I'm not exactly sure how to go about effectively following through with the off-board wiring to achieve the effect. At the very least, I would like to be able to affect the Rate of the LFO with an external expression pedal as well as having the tap tempo footswitch where it would be expected, so is there a certain way I might need to wire the pedal for this effect other than what you had suggested in this post:

Simply wire a jack to the 3 pads of the pot you want to replace, making sure that you wire it to be in compliance with the expression pedal you're using (they're all wired differently). Use a switching stereo jack so that when you unplug the expression pedal, the pot becomes active.

2) I would like to be able to apply a Tap-In to sync with an external multi input tap tempo switch that I would have on my board so that I can set the tremolo's modulation speed to the exact speed as my Hungry Robot's Starlite Reverb modulation once I have them both connected to each input within the separate tap tempo pedal. Is this what was being referred to as the last suggested modification on the build page referencing "Using the Tap Tempo LFO as a synch-able LFO" or will I have to apply something different?

3) LFO speed-monitoring LED and status LED - Just for clarification, if I wanted to have the LFO Rate LED continue flashing in bypass so that I may affect the speed while the status light is off, all I need to do is simply attach the postive and negative leads to the board itself where the "Neg" and "Pos" slots are located, correct? Or is there something else that I might need follow along with in order to achieve this?

I'm aware that I'll probably just have to a second LED in the traditional way most are wired through true bypass means in other pedals with the appropriate resistor if I wanted a status LED.

4) Finally, I'd like to know if it's possible for me to have all three of the Multiplier Knob (I'm going to be using a 1P6T switch if possible), Multiplier footswitch AND the On-Off-On Range Switch options applied within the circuit together? I had read that the range switch was to be used of the Multiplier knob was no longer necessary, however if I still wanted to utilize the Multiplier knob and still have access to the Range Switch for mor versatility, I'd love to.

I just needed to ask you these questions before I finished ordering so I know as to whether or not any of it would be possible. I'm hoping I'm not fantasizing beyond the realm of capabilities this circuit has to offer.

Thanks,
- Andrew C.

[lulu_joe13]

Andrew B. Campbell, That all seems do-able. Look at the schematics for the TapLFO chip from Tom Witshire. Every pot can have a jack to a expression pedal. And the TapLFO can be wired to take an external sync. And if you wire the on off switch as in the pdf, the Taplfo output is not grounded only bypassed so you can use the LFP circuit when the tremolo is bypassed. Joe.

[Taylor]

1) Expression pedal input - I would like the ability to apply an expression pedal input to the build that monitors both the optional Rate and Depth of the LFO. I'm aware that what I would have to do is apply an On-On toggle switch somewhere within this, but I'm not exactly sure how to go about effectively following through with the off-board wiring to achieve the effect. At the very least, I would like to be able to affect the Rate of the LFO with an external expression pedal as well as having the tap tempo footswitch where it would be expected, so is there a certain way I might need to wire the pedal for this effect other than what you had suggested in this post:

Simply wire a jack to the 3 pads of the pot you want to replace, making sure that you wire it to be in compliance with the expression pedal you're using (they're all wired differently). Use a switching stereo jack so that when you unplug the expression pedal, the pot becomes active.

There are a couple of ways to do it. Decide first if you want the expression pedal to add to the panel control, or to replace it whenever the expression pedal is inserted.

If you want to add to the panel control, using it to set the minimum speed for example, from which you'll sweep up, this will be more complicated as you will need to add an active summing stage for each control. That means extra components which you would wire on perf board or similar. Basically you need a little CV mixer which mixes the CV coming from the panel pot with that coming out of the expression pedal.

If you are OK with the expression pedal taking over completely for the panel control when the Exp. is inserted, then just use a stereo switched jack like this:

http://smallbear-electronics.mybigcommerce.com/1-4-in-stereo-nys212/

When you get one in hand, notice that when you insert a jack, three little metal arms rise up - these are the contacts for sleeve, ring, tip (in order of rising). The other ones, which don't move, are the switch contacts. You would connect the wiper of your panel pot (disconnected from the PCB) to the tip switch contact, then the [tip, ring, sleeve] connections to [the center pad for the control you're replacing, 5v, and ground] respectively. Now, when no plug is inserted in the jack, your panel control is active, but when it's inserted, the pot's value is no longer sent along to the TAPLFO and is replaced with that coming from the expression pedal.

2) I would like to be able to apply a Tap-In to sync with an external multi input tap tempo switch that I would have on my board so that I can set the tremolo's modulation speed to the exact speed as my Hungry Robot's Starlite Reverb modulation once I have them both connected to each input within the separate tap tempo pedal. Is this what was being referred to as the last suggested modification on the build page referencing "Using the Tap Tempo LFO as a synch-able LFO" or will I have to apply something different?

You just need to wire this jack in parallel with the tap switch, or if you only want to do the tapping from the external box, connect a jack instead of the tap switch. Left TAP SW pad goes to jack sleeve (ground), the right to the tip of the jack.

3) LFO speed-monitoring LED and status LED - Just for clarification, if I wanted to have the LFO Rate LED continue flashing in bypass so that I may affect the speed while the status light is off, all I need to do is simply attach the postive and negative leads to the board itself where the "Neg" and "Pos" slots are located, correct? Or is there something else that I might need follow along with in order to achieve this?

I'm aware that I'll probably just have to a second LED in the traditional way most are wired through true bypass means in other pedals with the appropriate resistor if I wanted a status LED.

Yep, you've got it right.

4) Finally, I'd like to know if it's possible for me to have all three of the Multiplier Knob (I'm going to be using a 1P6T switch if possible), Multiplier footswitch AND the On-Off-On Range Switch options applied within the circuit together? I had read that the range switch was to be used of the Multiplier knob was no longer necessary, however if I still wanted to utilize the Multiplier knob and still have access to the Range Switch for mor versatility, I'd love to.

I just needed to ask you these questions before I finished ordering so I know as to whether or not any of it would be possible. I'm hoping I'm not fantasizing beyond the realm of capabilities this circuit has to offer.

Thanks,
- Andrew C.

I'm actually not certain to what you're referring specifically when you say range switch, but I think maybe you're talking about just using the toggle to select from a couple of multipliers instead of having the rotary switch/pot control. So you wouldn't be gaining anything by having both. However, you can totally have the Multiplier knob/rotary switch plus the Multiplier foot switch together in a single build, no issues there.

[Andrew B. Campbell]

I thank you for the response. I can visualize what you've suggested.

Disregard the "Range" switch. For some strange reason, I had misread the .pdf and thought it performed something in a different manner than what I'm almost positive it actually does.

As far as the expression pedal is concerned, I really don't mind if the the secondary pedal replaces the rate or depth knob in this instance because if I need a specific speed after having altered it drastically with the expression pedal, all I'll have to do is tap that in with the momentary switch to arrive at the tempo that I need. What I had still wanted to do with this was have the ability to switch between which features I wanted to manipulate with the expression pedal alone, similar to something like this if it were possible.

This is literally the only inquiry I have left then. If this isn't possible with one input jack, will I have to apply a second and skip using a toggle switch altogether? The only thing I'm worried about is that if the toggle switch to change between either Tempo or Depth expression is that if one is selected and the expression pedal is inserted into the expression input, still both knobs might be disabled even though only the one selected feature is being manipulated. I'm fairly new at all of this, so I'm not sure if there's a way to bypass the Depth knob so that it still maintains its function if the toggle switch is selecting the Tempo expression while the external pedal is connected (and the same applying the other way around) or if I'm just making this much too complicated.

[Taylor]

http://imgur.com/9Jwbotb

I believe this should do it for you. I couldn't think of a way to do it with just a DPDT switch as in your drawing. Maybe somebody else can think of a more clever way that uses only two poles, but the solution drawn here needs three - one to switch the tempo control input between the pot and the exp., one for the depth, and one to connect either the tempo or depth pot's wiper to the switch on the jack.

Note that I've drawn the toggle switch with the lugs oriented the way they are on a real switch, so the switch drawn toggles up and down. Might be confusing because the lugs are drawn the other way on your drawing, so it might look like I've turned the switch sideways (and it's harder to read orientation on the 3PDT because of the rotational symmetry).

This is simpler than with most pedals because of the rare fact that this pedal's controls are all just voltage dividers sending a control voltage to 5 inputs on the TAPLFO chip. That means that to switch the pots around, we really only need to switch the wiper connections. If this was a more conventional analog circuit, you'd usually need to switch two or three contacts per pot and this simple wiring would not be possible.

EDIT! It just occurred to me that for safety's sake you should probably put a 1k resistor between 5v and the ring connection on the expression pedal. Otherwise when plugging the expression in you'll short 5v and ground for a second.

[Andrew B. Campbell]

http://imgur.com/9Jwbotb

I believe this should do it for you. I couldn't think of a way to do it with just a DPDT switch as in your drawing. Maybe somebody else can think of a more clever way that uses only two poles, but the solution drawn here needs three - one to switch the tempo control input between the pot and the exp., one for the depth, and one to connect either the tempo or depth pot's wiper to the switch on the jack.

Note that I've drawn the toggle switch with the lugs oriented the way they are on a real switch, so the switch drawn toggles up and down. Might be confusing because the lugs are drawn the other way on your drawing, so it might look like I've turned the switch sideways (and it's harder to read orientation on the 3PDT because of the rotational symmetry).

This is simpler than with most pedals because of the rare fact that this pedal's controls are all just voltage dividers sending a control voltage to 5 inputs on the TAPLFO chip. That means that to switch the pots around, we really only need to switch the wiper connections. If this was a more conventional analog circuit, you'd usually need to switch two or three contacts per pot and this simple wiring would not be possible.

EDIT! It just occurred to me that for safety's sake you should probably put a 1k resistor between 5v and the ring connection on the expression pedal. Otherwise when plugging the expression in you'll short 5v and ground for a second.

This helps tremendously. I genuinely appreciate it. I'll update once everything's finished.

[Smokinpcb]

I finished my tap tempo build the weekend before last and am still discovering all the things I can do with it. I had no problem with the build other than that I had a dud NSL-32 which I had to replace. I used a 1590BB and with 6 pots, 3 switches and an external tap input. It fitted perfectly. Here are a few pictures of the pedal

Was your LED working before you replaced it? I'm considering just replacing it as I've tested just about everything else in my build but was wondering if I'm having the same issue you had
Sorry for the the 4 year comment gap

[revolvercustoms]

Hello everyone, first post here and had some questions on the TTT if anyone can help me out id appreciate it. So I bought this board a couple years back to build for a friend. He ended up not wanting it so it sat on the shelf until I saw a demo of one and decided I would like to have it.  I started  putting it together and testing it with what I thought were issues but I am not entirely sure if it's in my head.  After hearing audio samples and hearing that this is a full deep sounding tremolo I was thinking I might have problems because mine does not seem all that deep trem described or that I have herd.  At first I though I had no trem and my signal was just being manipulated from the tap circuit so ill explain...

Here is what I have.
1: Have audio bypassed and engendered.
2: I am getting some modulation and the LED is functioning and reacting to the LFO and both the trim pots.
3: Both tap and EXP switches affect the signal and all of the pots have some noticeable effect to the circuit and it seems (Still on test rig) that It does cycle through most or all of the waveforms.
4: Also, I externally mounted the gain pot and that is more than obviously working...almost too much (seems that pot needs a smaller value).  SO, all that being said it would appear (even to me) that the circuit is working right? However after hearing several more samples, I still don't seem to get the smooth depth tremolo that others are. This is why I wonder if it's all in my head as I'm not familiar with a digitally controlled signal. So in an attempt to not drag  out a post for days and before I start digging into It, I decided to test things and provide in detail, in a single post what I do and don't have in case anyone has any advice at all.
So now that you know what I have, here is what I (for sure) have noticeable problems with. .....
1: My tap tempo switch seems to have an odd lag issue which I assume can be normal given its function. At times I barley tap it and it changes tempo, sometimes I have to hold it down for a bit to get it to change, sometimes it works as described and cycles through every tempo and sometimes only one or two.               
2: My biggest thought that there might be a problem is the fact that in all the posts I have read I have noticed that almost everyone does (and seems to love ) the wave distort function described in the BOM but My Wave distort Seems to do Almost nothing at all no matter what wave form I am in. IN fact, the only thing I hear at all is just when I am sweeping the pot back and forth but otherwise nothing all the way up or down. 
Because of this I decided to poke around because I do have an issue if that's not working and wonder if it's related to my week trem. I did all the standard, looking for and reflowing cold solders, traces, testing voltages etc and the pic below sort of details what I have found so I am hoping someone can point me in some direction of what to look for.

So in this pic the RED trace is reading all 9 volts up to the Vreg where it hits 4.5 volts and all the orange test points and orange dots are reading 4.5-5 volts so that's good. In addition to that all of the Green dots are reading 0 as I think they should. Also for reference I tested voltages on both IC's as shown below but they seem good to me
TL072
Pin 1=4.69
Pin2=4.67
Pin3=4.66
Pin4=0
Pin5=4.64
Pin6=4.68
Pin7=4.7
Pin8=9.39
PIC
Pin1=4.99   
pin2=2.06
pin3=2.04
pin4=4.48
pin5=0-2.8
pin 6=.002
pin7=0-3
pin8=4.48
pin9=.728
pin10=4.98
pin11=3.11
pin12=1.21
pin 13=2.93
pin14=.001   
Pin 5/7 change with led pulse. The led got brighter on when I touched pin 9 and when I touched pin10 the tempo or multiplier seemed to change if that means anything.
I know that I get audio from in to out but just to eliminate any variables decided to trace the trem circuit out and probe it at each test point as seen in this picture.

So from the test points in my pic I get a clean signal from points 1-4 but nothing after the 220k resistor nor on test point 5 (pin to of the IC) I get clean signal back on test point 6 and 7 (pin one of the IC) and clean signal on test point 8. I get no audio from point 9 where I would think I should start hearing the tremolo right? Because after that from point 10-ouput I get a tremolo effect. (also get trem effect on pin 7 of the IC). Shouldn't I get audio from point 5 and trem from point 9? I am hoping for any info if anyone can help. I am using an nsl-32 and have a spare and VTCL-3's I think but unknown if changing is necessary or will help and don't want to if I don't need to. I already had to swap the 3904 and unfortunately pulled the solder pads right off this board and that sucked. I was kind of disappointed with that because this bored looked well made and I know I did it the right way. I spend all day at my day job fixing and re-certifying %^&*pit equipment for the FAA so I literally do solder rework everyday and have all the right tools..O well not the biggest deal just scared to do anymore then I have to.   Anyway sorry for the long post if anyone sees anything wrong ...or nothing any thoughts or advice would be greatly appreciated. Maybe I just don't like the sound of the circuit? Who knows

[lulu_joe13]

 revolvercustoms, i can't get at my board. It's in a rack. But I will say, this is a very robust effect and if you think it"s not working the way it should you are probably right. I always step back at the point you are at and double check parts and values everywhere. So far I have never found that I didn't have a cold solder or broken trace or misplaced part in a circuit board I bought. I have never bought a malfunctioning board. Did you buy the pic with the board or from someone else? Look at the circuit diagram and audiotrace the signal path AFTER you are sure all the components are correct. Scrub the xtra flux off, etc. Also, if you have the switch wired in, remove it so you just have the board with input and output. Good luck and I hope someone more clever than I chimes in. Joe.

[Taylor]

1: My tap tempo switch seems to have an odd lag issue which I assume can be normal given its function. At times I barley tap it and it changes tempo, sometimes I have to hold it down for a bit to get it to change, sometimes it works as described and cycles through every tempo and sometimes only one or two.

You mention you work on electronics for a living so apologies if I'm telling you things you already know. 

It sounds like your switch contacts are bouncing, so fast double-taps in the switch mechanism are sending bad timing info to the TAPLFO chip. What type of tap switch are you using? The MCU has debouncing in the firmware, but it may not be enough if the switch is bouncing a lot. You can add some hardware debouncing, as shown here.
               

2: My biggest thought that there might be a problem is the fact that in all the posts I have read I have noticed that almost everyone does (and seems to love ) the wave distort function described in the BOM but My Wave distort Seems to do Almost nothing at all no matter what wave form I am in. IN fact, the only thing I hear at all is just when I am sweeping the pot back and forth but otherwise nothing all the way up or down. 

Do you by any chance have resistors installed in the spots to which the Wave Distort wires are soldered? You need to not fill those two resistors when the Wave Distort pot is used, as shown in the build docs.

So from the test points in my pic I get a clean signal from points 1-4 but nothing after the 220k resistor nor on test point 5 (pin to of the IC) I get clean signal back on test point 6 and 7 (pin one of the IC) and clean signal on test point 8. I get no audio from point 9 where I would think I should start hearing the tremolo right? Because after that from point 10-ouput I get a tremolo effect. (also get trem effect on pin 7 of the IC). Shouldn't I get audio from point 5 and trem from point 9? I am hoping for any info if anyone can help. I am using an nsl-32 and have a spare and VTCL-3's I think but unknown if changing is necessary or will help and don't want to if I don't need to. I already had to swap the 3904 and unfortunately pulled the solder pads right off this board and that sucked. I was kind of disappointed with that because this bored looked well made and I know I did it the right way. I spend all day at my day job fixing and re-certifying %^&*pit equipment for the FAA so I literally do solder rework everyday and have all the right tools..O well not the biggest deal just scared to do anymore then I have to.   Anyway sorry for the long post if anyone sees anything wrong ...or nothing any thoughts or advice would be greatly appreciated. Maybe I just don't like the sound of the circuit? Who knows

Not all points in a circuit are amenable to audio probing, so for example your point 5 (pin2 of the TL072) is in this circuit a "virtual ground," so it's normal that you'd hear no signal there. The same is true for your point 9, because it connects to the inverting input of the next gain stage and is again a virtual ground. So there's nothing out of place there.

What do you hear at pin 7 of the TL072? That's the output of the second stage.

To address your depth problem, first, just to be sure, you've experimented with different settings of the Depth control, and you do get noticeable change in depth, but just not a huge change?
How does turning the trimpots affect the depth of your tremming? At all?
Apart from the amount of volume modulation("depth"), is the audio sound itself weak and noisy or pretty normal?

[revolvercustoms]

Thanks for the response Taylor, I figured it was a timing issue with a switch. That is an interesting read on debouncing and I will look into that at a later point. The switch I am using is a soft touch normally open momentary. To be Exact here is the link to the part.
http://www.conrad.com/ce/en/product/701083/Pushbutton-250-Vac-3-A-1-x-OffOn-SCI-momentary-1-pcs

As far as the wave distort here is a pic of how I have it wired and from day one I left the 10k's out.

I did test the pot last night and it is working as it should and did test for continuity between each lug on the pot to the solder points on the back of the board and all checked out there as well, Just an fyi...still does nothing at all and I have no reference to what it should do...lol
Now as for the audio path I did look at it little more last night and noticed the virtual ground so my apologize for missing that, that's a my bad so everything there seems to check out ok then. On PIN 7 of the opamp I am getting a trem affected signal when probed as well as from test point 10 all the way to the output.
Now, as far as the depth of the tremolo I noticed that I didn't do a great job explaining that so I'll try to explain it a little easier. Aside from the "wave distort" having no function I think the rest of the controls and the circuit for that matter are doing their job and seem to at least function as intended because I get a noticeable change in the effect when I use them. However, you asked if the trimpots had an effect on the trem itself and would say not really. one I notice just seems to turn the led on/off and the other seems to control the strength of the rate led and seems to increase ticking, noise and ads a bit of gain.
The point I was trying to make of the tremolo sounding week could be explained better so I will use a better example. I of all people should know you can't always trust an audio sample when comparing things but again it's my only reference. So to explain my issue audibly let's just say for example that this pedal is a Univibe. In all the samples I have listened to it seems like everyone has a full functioning univibe and mine though it works, sounds as if it has no light shield if that helps. I am getting a tremolo effect but I am not getting the Phasing depth that I hear out of others who built this. It's almost like light is escaping from my opto which it's not (at least visibly anyway) or there is too much resistance on it or not enough input current to the LED side of it. Hopefully that makes more sense to you. I guess I was just curious if there is anywhere in the circuit that I could look at that might be suspect to this type of issue before giving up on it or replacing un necessary parts.

I did have a question related to the opto though, I was trying to see if I couldn't get the phase depth figured out (or just wanted more) if there was any mod I could come up with to increase the input current on the LED side in hopes to increase phase depth (i know this is the function of the trimmers but they have little affect.) I assumed this was thought of when the circuit was designed but was curious why the Nsl-32 was chosen. Of course I bought and used a couple as the BOM recommended them. Just curious because I had some VTL5c3's lying around and never used a NSL-32. Aside from them being cheaper than the VTL I looked at the datasheets and they appear to be damn near identical. However, I did notice that the response time of the VTL5c3 was much faster than the NSL.  Granted the difference in turn on time is marginal and likely impossible to notice, I did notice the decay time is almost 5 times as fast. Was wondering if the faster response times would help with ticking and add any noticeable depth, especially in the square wave and random settings? Have you tried one at all and notice anything or in this type of application would it even make a difference enough to notice? Just curious...Damn! I just nerded out, I need to go have beer and man up a bit...lol thanks for all the help folks.