NEW PRODUCT: Taptation Tap Tempo controller

[mrsuspend]

Thanks very much Aron! Will post results as soon as I have the time to test my taptation board (might be a few days).

/Magnus

[aron]

Great! Will be interested in what you find.

[blearyeyes]

Aron,
Did you get my PM?
DS

[aron]

Yes. Lets see what Magnus finds.

[blearyeyes]

After reading the original posts, think about it, the only interface between the delay and the taptation is the digital pot and pin 6 of the PT2399.
Now reference this:

The TapTation uses a 100K pot for a max around 1125ms

OK, there are 2 ways to debug this.

1: Tap something slow - like 2 seconds. This should set the max time to 1125ms (1.125 seconds). From the above quote, the LEDs should flash roughly 1.125 seconds AND the digipot should be around 100K.

If it's around 100K, the taptation is working properly - time to look at the rest of the circuits (PT2399 etc...)
If it's NOT close to 100K then the code that sets the digital pot is sending out an incorrect value (more unlikely) or, the digital pot is not close to spec.

So people, tap slowly and measure your digipot value. It looks like pin 5 of the digipot and ground of the PT2399. Does that make sense or am I overlooking something?
You probably have to pull the PT2399 and measure the digipot value.

Here's more food for thought. If you tap slowly and the LEDs flash slowly etc.... the timing code is working. The more I think about this, it's pin 6 of the PT2399 being extremely sensitive or PT2399 scaling differently.

SPI code is super easy:
http://arduino.cc/en/Tutorial/SPIDigitalPot

I tried to do this but the circuit resets faster than that the speed you recommend. So I am trying to use the speed pot to get the slowest speed. tested the speed pot and it is much lower than 100k. Going to replace and test again.

[mrsuspend]

Ok, test done.
First of all, I'm using the JMK Modulation taptation board:
http://jmkpcbs.com/wp-content/uploads/2014/03/Modulating-Taptation.pdf
I realise this is not the optimal way to perform tests but all aspects of the board (PWM, Tempo switch, manual tempo pot) seem to be working as expected.
I disconnected the board completely from the Echo Base (which in itself is working perfectly). I connected the DMM to pin 5 of the digipot and to ground.
The manual tempo pot connected to the PCB measures 98.5K.
First off, I noticed that tapping at 2 second intervals does not work, I had to be much closer to the max value of 1125ms for the tap to register (as already noted by blearyeyes).
The highest digipot value I was able to produce while tapping was 78.4K. When setting the max tempo manually the digipot measured 80.1K.
Judging the LED is obviously difficult but it seemed to sync well with the tempo I was tapping.
I'm guessing breadboarding the digipot to measure it isn't very complicated, If I get instructions I'd be happy to do it.  

/Magnus  

[aron]

So you were right, it's probably the digipots. Will see what Andrew says.

[blearyeyes]

The Max delay output of the PT2399 is governed by a resistor on the delay board circuit.
Usually limited to 600ms or less due to noise issues.

[blearyeyes]

Any news? I didn't send the boards. Would sending them help? I put them in the fail box until all the PT2399s show up..first board to beat me! Pretty disappointed at this juncture.

[aron]

No news yet. Let me know how your PT2399's work. I notice that people are getting their PT2399 from somewhere else. How are the other people getting this to work? I think it's a combination of the PT2399 and Digital Pot. Seeing as the PT2399 is non-linear in terms of delay, I'm hoping your batch of PT2399 will work.

[blearyeyes]

No luck, tell me where others are getting the good chips please...
First 10 PT2399s are the same faster speed...
I just want to get these two pedals finished.

[blearyeyes]

I notice that people are getting their PT2399 from somewhere else.

Aron,

Could you PM me regarding where the "somewhere else" people are getting their PT2399s from and if you have found a better place to source digipots?

Dan S.

[aron]

People I talk to are getting them from Tayda and it apparently works for them. Most have custom boards they made themselves. They are using the chips I sent and Tayda chips.

[chuckd666]

Hey Aron et al,

I bought a taptation with digipot from the diystompboxes store in late October 2015.

I used it with the Hamlet+ PCB from JMK. I'm having the same issues described above with tap tempo inaccuracy.

My PT2399 is from Paul at diyguitarpedals.com.au. They are legit and have never given me any issues aside from this thankfully.

Can anyone explain to me how to measure digipot resistance to see if it needs replacing?

Regards

Chuckddddddddd

[blearyeyes]

I believe pin 6 on the PT2399 socket is the control resistance.

[blearyeyes]

Let me know if you source some good digipots that work. I never did get mine to work.

[mrsuspend]

Let me know if you source some good digipots that work. I never did get mine to work.

I don't think it's a matter of sourcing, it's simply that the tolerance is 20%. I've bought a few and think at least one of them is alright although I haven't had the opportunity to test it properly yet. Mind you the 100K ones a probably few and far between. It's a question of luck really... 

/Magnus

[chuckd666]

So I measured between pins 6 and 8 on my MCP41100 (with delay time pot at full) and it reads just below 60k. Useless?

[blearyeyes]

Out of spec. 40% ?

[chuckd666]

I have ordered 5x more ICs to see if that'll solve it. The one I have is strangely out of spec, but I can't see any other issues that'd cause this. Perhaps I'm not tapping a long enough delay, but I figured just maxing the delay knob would have a similar effect..? Or at least reach the ballpark?

See page three of this PDF for the schem in question. http://jmkpcbs.com/wp-content/uploads/2014/03/Hamlet+.pdf