Building the tap tempo tremolo

[Vince_b]

I have a question about using rotary switches for the waveform and multiplier controls. I have followed the instructions on the Tap Tempo LFO datasheet to wire the rotary switch for the waveform control but I'm not sure how I should do the one for the multiplier.
On the datasheet (p. 8 ) it is said that: "The top two options are not used for the Multiplier" Does that mean that two of the 10k resistors must be removed from the resistor string? Or do I have to keep all the resistors from the string and only remove the first two connections that go from the rotary switch to the resistor string?

[.Mike]

Looking at the datasheet, it is the second one.

The datasheet also says: Note that values 6 & 7 are not used (set to x1) so the maximum useful CV is 3.75V

I did a quick sim of the string of resistors, and recorded the voltages. Check it out:



As you can see, the junction of R1 and R2, and the junction of R2 and R3, are both above the maximum useful CV of 3.75V, so you don't want to use them (they'll set the multiplier to 1, which is already covered by one of the throws of your SP6T rotary swtich). The other six resistor junctions are the usable voltages.

You can sub R1, R2, and R3 for a single 25K resistor (or probably a common value close to that, like 24K).

Mike

[Vince_b]

Thank you for your quick reply Mike

[Taylor]

Keep in mind that that 3k6 resistor that feeds the clockwise lug of the multiplier pot limits the max voltage to 3.75v already. So if you're tapping from some other 5v point, Mike's diagram has you covered, but if you were going to take the positive voltage from the multiplier pot's clockwise pad, you'll need to adjust for that.

[moisho]

Mine is mounted and working fine.

(Thanks Taylor for your excellent PCB)

Maybe, as someone of you said, using a pot to select the waveform is not the best way. I'd like a 3 pos. switch to select SINUS, PULSE or RANDOM. Easy mod.

btw, I recommend the multiplier switch. It is very useful.

I'll try to upload some picture.

[Vince_b]

Taylor, I understand what you just said but I'm not really sure how I should adjust for that if I want to use the positive voltage from the multiplier pot's clockwise pad.
If I want to be able to use Mike's diagram, is it as simple as replacing R8 (3k6) by a jumper?
Another way to do it will be to keep R8 like it is and change the values of the resistors in the resistor string. But I don't know what those values should be nor how I could calculate them.
And just to be be sure, as there is no resistor that limits the max voltage to the waveform pot, if I want to use a rotary switch for that I don't have to make any adjustment like the one that is required in the multiplier case, right?

[Taylor]

Taylor, I understand what you just said but I'm not really sure how I should adjust for that if I want to use the positive voltage from the multiplier pot's clockwise pad.
If I want to be able to use Mike's diagram, is it as simple as replacing R8 (3k6) by a jumper?

Yes, that's one way and it will work fine.

And just to be be sure, as there is no resistor that limits the max voltage to the waveform pot, if I want to use a rotary switch for that I don't have to make any adjustment like the one that is required in the multiplier case, right?

Right, no adjustment necessary there.

[Vince_b]

I have just finished building my tap tempo tremolo. It worked fine on the first try, no debbuging to do! Thanks to everyone who have contribute to this fantastic project and a special thank to Taylor and Mike who helped me with the wiring of rotary switches.

Here is a picture:

When I will have time to finish the enclosure I will also post a picture in the picture thread.

But the only thing that bothers me with this tremolo is the brightness of the led. To remove the ticking I had to set the trimpot for the led to almost full intensity and it's so bright that I can't even looks at it when it's engaged. I have sanded the top of the led but it is still too bright. Does anyone have a solution for that?

[Taylor]

I would swap out the 330p for something like 1n or 2n2. That should sort the ticking and you can adjust the trimmers to a more reasonable area.

[mth5044]

Hey Vince, looks great. Any chance you have a picture of the top? I know you said it isn't done, but I'm still deciding on a layout 

[azrael]

Has anyone made clips of their Tap Tempo Tremolo? I'm waiting ona  few more parts and mine is done.

[.Mike]

I put up some crappy clips in this topic. The clips are in the first post, and there is a longer demo further down the page.

It's not a tap-tempo tremolo, but it uses the earlier non-tap VCLFO and a nearly identical supporting circuit. As far as I am aware, the waveforms are the same between the TAPLFO and VCLFO, so it should give you a very good idea of the flexibility and sound of the effect.

Mike

[azrael]

Got mine working great....only issue is that the Waveform Step Switch I wired onto the expansion pads doesn't seem to work? I used the same kind of switch that I used on the tap switch.

Any ideas why?

[Taylor]

That switch doesn't step through the waveforms, it steps through multipliers. Do you have the 10k resistor on the edge of the baord next to the exp pads soldered in?

[azrael]

Oh, read the info wrong! Doh.

Yes, I have the left most soldered in, but I also have the wave distort soldered in.

[Taylor]

Well, the wave distort won't have anything to do with the multiplier switch. So does it work to switch through multipliers?

[azrael]

Hm, I don't think so. Should the leftmost resistor be in there or not?

[Taylor]

Yes, that leftmost 10k should be there no matter how you have the pedal configured. Is your switch normally open or normally closed (should be normally open)?

[jonny]

I finally built this but have some pretty bad ticking, only on the square wave though. I can't get rid of it at all, I've upped the 330p to 1.3n and it's still there. I'm using an NSL-32 that I got from taylor, and the only thing different I did was instead of using a 2n3904, I used a BC550 - which shouldn't matter? No wave distort knob. Any ideas? (almost everything else seems fine, perhaps a little ticking on a few of the other settings but not so bad)

also, I have ticking in bypassed mode. Setting the trims the ticking disappears in places but then you use a lot of volume, as I guess it turns off the nsl.

[azrael]

Normally open, I believe. It's the same kind of switch I used for the tap switch.

Oh, and I used the NSL-32 from smallbear, no problems with ticking whatsoever. I thought that might be useful to know.