Tap tempo delay modulation (uk-electronics)

[brejna]

I was thinking is it possibile to add modulation on the uk-electronic kit on the pin 7 of mcp41050..

[brejna]

Any ideas? 

[RobA]

I don't know this design, and I'm not quite sure what you mean by applying modulation to pin 7, but the PB0 pin is just the output of a digital pot. It's pretty much equivalent to lug 3 on a normal pot.

The MCP41050 uses SPI, so in general you'd need to modulate the setting via the digital output from the MCU. Maybe you could modulate the control pot setting that the MCU uses. There are ways you could do that, but the digital pot is only 8-bit. The resulting output is going to be noticeably stair-stepped.

[brejna]

I've seen that taptation uses pin 7 for modulation, so I thought it could work.

[RobA]

I've seen that taptation uses pin 7 for modulation, so I thought it could work.

It looks like the Taptation is using a MOSFET to change the total resistance the PT2399 sees. You could do the same thing on the other design if you can get a correct level of varying control voltage on whatever you are using to modulate the resistance. You wouldn't have to do it off of pin 7, although that could work. You could do it off the output pin to the PT2399 as well. You could probably rig up a setup for doing it with an LDR.

[brejna]

Do you mean to connect modulation like on the aquaboy2012 or?

[RobA]

Do you mean to connect modulation like on the aquaboy2012 or?

I don't know the Aquaboy circuit, so I can't say. But here's what I was thinking. The taptation wires pin 6 of the PT2399 to the wiper of the digital pot and then the other lug/pin of the digital pot (PB0) to the BS170 and the depth pot. When you zero the depth pot, it takes the BS170 out of the circuit and PB0 is connected straight to ground so only the value of the pot sets the delay time. When the depth pot is raised, some of the current goes to ground through the BS170, which I assume is being modulated by pin 6 from the MCU. So, I'm assuming it's working like the JFET in a Phase 45. So, from your original question, I think you could do the exact same think if you included a modulation source voltage to control a BS170 and you lifted the PB0 bin and sent it through an arrangement just like the taptation. But, I also don't think it matters what side of the digital pot you do this on, so you could just leave the board as it is with PB0 going to ground and then putting the modulated resistance on the output from PW0. The other stuff I was referring to was just that I think you could use other modulate-able resistances instead of the BS170, something like a JFET or an LDR. I haven't tried any of this though, so I don't know that it will work or how well the PT2399 will handle it.

[brejna]

Do you mean to connect modulation like on the aquaboy2012 or?

I don't know the Aquaboy circuit, so I can't say. But here's what I was thinking. The taptation wires pin 6 of the PT2399 to the wiper of the digital pot and then the other lug/pin of the digital pot (PB0) to the BS170 and the depth pot. When you zero the depth pot, it takes the BS170 out of the circuit and PB0 is connected straight to ground so only the value of the pot sets the delay time. When the depth pot is raised, some of the current goes to ground through the BS170, which I assume is being modulated by pin 6 from the MCU. So, I'm assuming it's working like the JFET in a Phase 45. So, from your original question, I think you could do the exact same think if you included a modulation source voltage to control a BS170 and you lifted the PB0 bin and sent it through an arrangement just like the taptation. But, I also don't think it matters what side of the digital pot you do this on, so you could just leave the board as it is with PB0 going to ground and then putting the modulated resistance on the output from PW0. The other stuff I was referring to was just that I think you could use other modulate-able resistances instead of the BS170, something like a JFET or an LDR. I haven't tried any of this though, so I don't know that it will work or how well the PT2399 will handle it.

Thanks for this, i will order few breadboards soon and will test these ideas. I hope that it works