Building the tap tempo tremolo

[Johnny B]

A few weeks ago, I decided to built the tap tempo tremolo after making an EA tremolo. I ordered all the parts and even managed to find a supplier for the NSL-32 in RS components here in South Africa. They were on 14 days delivery from the local supplier sourced from RS in the UK.
Today I received a call from the local RS people to say that they now cannot source the NSL-32 even though it states availability on their website and they accepted my order a week ago. So now I'm in trouble. I cannot find any other source in South Africa and most overseas suppliers require minimum order quantities and high shipping costs.
Is there any kind soul who would be prepared to put two in an envelope for me and post them to South Africa? I'll happily pay all the costs.
Thanks in anticipation.

[Johnny B]

Hi again from South Africa. I am battling to find NSL-32 optocoupler down here in SA but I might be able to find something in the Perkin Elmer VTL5CX range. I know that at one stage 'thehoj' was deliberating which one to use. Has anyone used a Vectrol. Which one did you use and did it work OK?

[Taylor]

I haven't used vactrols in this circuit, but they should work as long as they have a similar on/off resistance and speed. There's a big perkin-elmer datasheet with the info for all the vactrol series to compare.

[Jamforthelamb]

 Got my ttt built, lfo works and no ticking so far. Biggest problem right now is the signal is very clipped/distorted. Any ideas were to go with that?

-kevin

[Taylor]

You probably need to turn down the gain (trimpot above the tl072). This may mean readjusting the opto trimmer to get unity gain.

[Jamforthelamb]

I've played with all the trim pots and the signal when it comes through is always clipped

[Taylor]

Even at minimum gain? If so, I guess the first opamp stage is clipping - possibly the biasing resistor has a bad solder joint? What kind of signal are you putting into it?

[Jamforthelamb]

Which resistor woud that be? I was testing with an old teisco with a single coil in the neck.

[.Mike]

I don't see any biasing resistors in the schematic, just pull-downs. It looks like Vref is connected straight to the opamp on the schematic. Either way...

Check the two side-by-side 100k resistors that create Vref. Each should measure about half of the power supply on the ends closest to the middle of the board. If you get half of the supply voltage there, check pins 3 and 5 of the opamp. Both should also be at about half of the supply voltage.

You can also check the two 220k resistors, which set the gain of the first stage. Double check to make sure they are they right value. If, for example, you accidentally used a 22k and a 220k, you could end up with a gain of 10 instead of a gain of 1. That could overload the second stage, which is set by the LDR side of the Vactrol, and the 10k trimpot that is situated (I think) between the Vactrol and the 330p capacitor.



Mike

[Taylor]

I guess I should go look at the schem rather than just go on memory!  It's been long enough since I looked at it that I was thinking that they were non-inverting amplifiers.

Good suggestions, Mike.

[Jamforthelamb]

Thanks guys, hoping to get a look at this tonight, and let you all know my progress

-Kevin

[Ultrakd]

Ok I was just able to get back and reflow my solder joints and to rewire the board. I was wondering though for the LED that blinks constantly, can I put 2 there or will the 2 trimmers not be able to take out the ticking?

[Jamforthelamb]

Hey All,

Did some voltage testing last night, and didn't find anything immediatley alarming. Voltages at the recommended test places were about half of the incoming voltage from my power supply, so on a whim and a hunch I decided to try sticking in a diffrerent TL072. Boom! We got tremolo! I'm still working on tuning the circuit, now that I have the a working audio section I've got the dreaded tick that some others have encountered. I initally had two NSL32s to try, but the first one's leads broke off from me trying to figure out which way it went in. I also may try the cap change that was mentioned earlier in this thread.

Does this Tremolo get very deep/choppy? I've tried it a couple times with everything cranked (depth and trim pots) so it was clicking like crazy, but still didn't seem to get real deep. I need to spend some more time with it as I don't have anything labeled, so I'm not sure what waveform I was on etc (I know squarewave is the best for the super choppy stuff). As always, I will post my progress.

Thanks!

-Kevin

[.Mike]

I also may try the cap change that was mentioned earlier in this thread.

If I remember right, isn't that just increasing one of the caps? You should be able to see if that will work for you by holding/jamming a cap in parallel with the cap that is currently in place.

Does this Tremolo get very deep/choppy? I've tried it a couple times with everything cranked (depth and trim pots) so it was clicking like crazy, but still didn't seem to get real deep. I need to spend some more time with it as I don't have anything labeled, so I'm not sure what waveform I was on etc (I know squarewave is the best for the super choppy stuff). As always, I will post my progress.

Yep, definitely gets choppy. You have to use a combo of square wave and high speed, and then adjust the wave distort knob. Stick wave distort in the middle, set for square, and crank the speed up. Adjust the wave distort to get the choppiness you want.

Mike

[Jamforthelamb]

If I remember right, isn't that just increasing one of the caps? You should be able to see if that will work for you by holding/jamming a cap in parallel with the cap that is currently in place.

That was my exact plan  . Looks like it was recommended to use a 1nf in place/on top of the 330pf in the audio section. Going to try that tonight hopefully.

Yep, definitely gets choppy. You have to use a combo of square wave and high speed, and then adjust the wave distort knob. Stick wave distort in the middle, set for square, and crank the speed up. Adjust the wave distort to get the choppiness you want.

That was my next question. When using the wave distort knob how does it effect the sound as you turn it left to right. Is it less distorted/normal all the way to the left adding more as you turn right, or something different?

Thanks!
-Kevin

[.Mike]

That was my next question. When using the wave distort knob how does it effect the sound as you turn it left to right. Is it less distorted/normal all the way to the left adding more as you turn right, or something different?

It's a misnomer. It is the waveshape that distorts, or more accurately skews based on the wave distort setting. There is no audible distortion.

Take a look at these images, and see if it helps understand what it does:

http://www.electricdruid.com/images/lfo/PDDiagramV9C.gif



And finally, here is an audio sample I made to demonstrate the wave distort feature using the Taplfo's predecessor, the VCLFO.

Wave Distort demo, Square wave, Full counter-clockwise to full clockwise: Link



Mike

[Jamforthelamb]

Hi Mike,

Cool, thanks for the info. I got that it doesn't actually "distort" the sound, but rather the way the wave is shaped. I was questioning more on the way the knob functioned. So, it looks like the wave is not effect in the center position, and then will change depending on which way you turn it. That about right?

Thanks!
-Kevin

[Jamforthelamb]

Got to spend some more time with my TTT. With the wave distort knob centered had a much easier time dialing almost all the click out (except on extreme settings). It's so tight to push a cap over the 330pf cap that I may have to try and just trim it out and solder in a different cap, but the clicking last night in my smaller amp was nearly gone so I may not have to. It will really depend on how it plays with my main amp tonight. All I have left to do is make a decal for it, and wire the LED to the bypass switch using Taylor's updated layout. It's too embrassing to photograph right now cause the enclosure is naked and tattooed with sharpie lol.

Thanks again for everyone's help!

-Kevin

[bsmcc2010]

just wondering-is there a way to build a 2 knob (speed and depth) type tremelo with a tap tempo input jack? does anyone have a hero layout for it?

[Ultrakd]

Ok I think I messed up my board. The first time I wired everything up I used 22awg wire which I had to shove in some places. I went and  got some 26awg now and when I was pulling some of the wires out I pulled out some of the pads. Did I mess up my board, should I get a new one? Another one of my problems is I haven't been able to get the ticking to go away from the light.