Technical reason taptation won't work on the Zero Points?

[sdb guitars]

The idea of a longer "clean" delay time interests me... on the ZPDD, with the PT2399's in series, has anyone worked out what mods would need to be made to the mirror circuit connected to the pin 6's to connect to the TapTation "pin 6" pad?  I've considered buying a ZPDD and a TT daughter board and just diving in, but I'd love to hear that someone else has tested it first.  LOL

[neiloler]

If someone wants to donate a taptation kit, I'll gladly try it out.

[jasonstomps]

What I was going to try, to get tap on the ZPDD, was to omit the current mirror section and build up the taptation circuit using a MCP42100 digital pot instead of the MCP41000.

[sdb guitars]

I'm curious what would happen if you fed the tap signal into the mirror array... would you get essentially double the delay that your tap indicated because each chip would be delaying your signal by the amount set by the tap switch?

[jasonstomps]

I''m not sure if you could feed it into the mirror, the taptation circuit is controlling resistance to ground basically, where the mirror is actually controlling the current into pin 6.

[neiloler]

I still want to sub out the standard PCB that everyone uses for the taptation (pin 6 through digipot to ground) and make one that allows for an exact swap out of the delay time pot instead.

[jasonstomps]

Is anyone familiar with using a MCP42100?  From the datasheet (http://www.mouser.com/ds/2/268/11195c-64695.pdf), it looked like it was a good solution for adding tap tempo to ZPDD, but I'm hitting a snag where the delay is stuck on medium delay regardless of delay pot or tap tempo setting.  Based on the tempo led, the taptation side is working correctly, but does not change the actual delay length.

The MCP42100 appeared to be basically the same as the MCP41100 except with a second digital pot section and reset shutdown pins.  Anways, I think the reset shutdown pins are where I'm going wrong, but I'm not sure what needs to be done to fix it.  Right now I both reset & shutdown pins connected to nothing. 

Any thoughts?

[jkokura]

Yes. I'm ahead of you. I had a 42100 arrive in the mail, and I'm getting close to having the time to do some testing.

Jacob

[jasonstomps]

Yes. I'm ahead of you. I had a 42100 arrive in the mail, and I'm getting close to having the time to do some testing.

Jacob

Great Jacob, glad someone with some smarts is looking into this. 

A heads up, I think I messed up my MCP42100 chip by letting the shutdown/reset pins float instead of hooking them up to the 5V.

-Jason

[bevibes]

Hello,

I am a beginner in electronics so sorry in advance if my solution is stupid.
I looked at the diagrams of the TT and the ZPSDX and I concluded that:



What do you think of this?


I have not tried the ZPSDX so I do not know if the modulation section sounds so good but the alternative already proposed by jkokura (using PWM modulation and deleting modulation part, so use the modulation of TT) would the simplest solution.

Thanks

[jasonstomps]

I think you're going to have to remove the entire current mirror section, including the transistors and resistors you have highlighted in blue. 

The way I got the Taptation working with the Zero Point DD, was to hook each pt2399 pin 6 up to it's own MCP41100 and then running them in parallel into the Taptation.  I didn't experiment thoroughly with the modulation under this setup, but I did seem to have it working with two individual mod paths running from the MCPs in parallel to Taptation pin 6, being controlled at the same time with a dual pot.

[neiloler]

I'm taking the plunge and going to play around with Taptation for the ZPDD.

Jasonstomps, do you have a schematic (or could you pretty please draw one) for the exact setup you're talking about? Did you take the MCP41100 and use them to control pin6 to ground, ala the standard Taptation docs (I'm guessing they'd go in place of the transistors controlling the pin6 to ground)...?

You just put the MCP41100 chips in parallel so they'd both take the SPI commands at the same time...?

[jasonstomps]

Here's a crude schematic of what I did.  Removing all components attached to both pin 6s on the zero point schematic.  Now for mine, for whatever reason, I need to put 3.6k resistors between the MCPs and pin 6s to get the tempo LED to sync up with the actual repeats.

[neiloler]

Awesome, great to know! Thanks for sharing the info! I'll post back with my findings myself (I'm going to try a slightly different approach of simply replacing the delay pot itself with the digipot and see what I get)

[neiloler]

Did you have any trouble with the digipot being 100k and the ZPDD's delay pot being 50k per the spec? Any weirdness there?