Introducing a New Member

Thanks for introducing vwolff to the element14 community John

Welcome Von! Those bio-electronic projects John mentions sound intriguing, hopefully you can share some more about those at some point

Thank you rachaelp.  I've been working on a neuromodulation stimulator. The neuromodulation stimulator has been in research at University of Wisconsin at Madison for over 10 years under the name Portable Neuromodulation Stimulato (PoNS). I've been following that development and interpreting a research paper:

     https://www.researchgate.net/publication/321174000_The_Portable_Neuromodulation_Stimulator_PoNS_for_Neurorehabilitation .

It's been used to create new neural pathways in patients who suffer from traumatic brain injuries, Parkinson's disease (My condition) and multiple sclerosis. Most of my work prior to retirement has been in the digital realm with very little analog circuit experience. I'm having trouble interpreting the analog interface between the electrodes and the human tissue.  What is your experience with analog circuits?

Thanks again,

Von

Hi Von,

Interesting document. So sorry to hear about your condition, I too know someone suffering from it.

Most of the document was understandable (I skimmed over some parts, but tried to understand the sequence of signals and the output circuit), however is there a copy of it with the diagrams, since that would remove a few areas that were slightly unclear.

I can think of some ideas that could replicate that functionality, but with a bit more flexibility for future tweaks. I'm guessing you're planning to use some microcontroller for the sequence generation? For the output a _lot_ of MOSFETs could be used, or arrays of drivers. A few discrete voltage levels could be available to assign to each channel (just needs a lot more MOSFETs - fortunately they are cheap). But the diagrams from that paper will help, to confirm my understanding.

Some sketching and simulation would be needed, and some thinking about what additional flexibility is needed.

John,

The signals look good.  I really like the way you were able to modularize the driver onto a single adapter.  Very cool!

Gene

Hi Michael,

I love electronics, there are so many elegant ways to get from point A to point B. there are even some inelegant ways as evidenced from some of my own designs. I will mention your idea to Von. We are probably locked into the present path though as the parts have been ordered and time is of the essence to Von. Thank you for the idea. I am always interested in what you have to say.

John

I've come very late to this discussion - only spotted it today.

This may be a daft suggestion but here goes:

Why not just use a quad op amp as the driver - may not be optimum for cost but an OPA4192 can do 0 - 30V, 20V/us slew rate, 10 mA drive easily, more for non continuous operation.

Can get it in a TSSOP14 package so it's tiny. Resistors in 0402 or 4 in 1206 won't take up much space.

Let me know if the idea is appealing and I'll think of a circuit.

MK

Hi Gene,

Von and I spent a couple hours today testing the MOSFET circuit that you recommended. We are using a TC2320 chip which has one N Ch and one P Ch chip in an SOIC 8 package. This allows us to put one driver circuit on each bread board adapter. I was also able to pull the other peripheral passives up onto the little adapter board. We will be able to drive one each of Von's 16 channels with each module and all we will have for external connections are power rails and one input and one output. We both want to thank you for the good solution to increasing the output of the device.

The blue is the signal from the generator and the yellow is the output from the MOSFET module.

John

John,

The N-Channel MOSFET acts as an open drain inverter, so replacing it with an open collector inverter works fine.  Or, you could leave out the 7406 and drive an N-channel MOSFET directly (as shown in the initial reply).  Either way should work fine.

Gene

Is there any advantage to the two stages using the P Ch as a switch and the N Ch as a driver? I have some TC2320 chips which house one of each.

John

John,

Here is a quick sketch of how you could do this with a 7406 (open collector) to switch the high-side MOSFET.  Shown is a single channel.

Gene

Hi Gene,

I am trying to set up a bread board of the circuit you proposed using the BSD 223.  If I am using the output of a 7406 for the input how do I interface. Do I have one channel or do I have two with the 2 inputs and 2 outputs. Von may understand but I don't and I am trying to set up the experiment before he comes in the next few days.

John

Hi Gene,

I am trying to set up a bread board of the circuit you proposed using the BSD 223.  If I am using the output of a 7406 for the input how do I interface. Do I have one channel or do I have two with the 2 inputs and 2 outputs. Von may understand but I don't and I am trying to set up the experiment before he comes in the next few days.

John

John,

The signals look good.  I really like the way you were able to modularize the driver onto a single adapter.  Very cool!

Gene

Hi Michael,

I love electronics, there are so many elegant ways to get from point A to point B. there are even some inelegant ways as evidenced from some of my own designs. I will mention your idea to Von. We are probably locked into the present path though as the parts have been ordered and time is of the essence to Von. Thank you for the idea. I am always interested in what you have to say.

John

I've come very late to this discussion - only spotted it today.

This may be a daft suggestion but here goes:

Why not just use a quad op amp as the driver - may not be optimum for cost but an OPA4192 can do 0 - 30V, 20V/us slew rate, 10 mA drive easily, more for non continuous operation.

Can get it in a TSSOP14 package so it's tiny. Resistors in 0402 or 4 in 1206 won't take up much space.

Let me know if the idea is appealing and I'll think of a circuit.

MK

Hi Gene,

Von and I spent a couple hours today testing the MOSFET circuit that you recommended. We are using a TC2320 chip which has one N Ch and one P Ch chip in an SOIC 8 package. This allows us to put one driver circuit on each bread board adapter. I was also able to pull the other peripheral passives up onto the little adapter board. We will be able to drive one each of Von's 16 channels with each module and all we will have for external connections are power rails and one input and one output. We both want to thank you for the good solution to increasing the output of the device.

The blue is the signal from the generator and the yellow is the output from the MOSFET module.

John

John,

The N-Channel MOSFET acts as an open drain inverter, so replacing it with an open collector inverter works fine.  Or, you could leave out the 7406 and drive an N-channel MOSFET directly (as shown in the initial reply).  Either way should work fine.

Gene

Is there any advantage to the two stages using the P Ch as a switch and the N Ch as a driver? I have some TC2320 chips which house one of each.

John

John,

Here is a quick sketch of how you could do this with a 7406 (open collector) to switch the high-side MOSFET.  Shown is a single channel.

Gene