I’ve been playing with the idea to design my own Estim powerbox. Finding this forum was the last push I needed to get my procrastinating ass on the job! I have a few design-features in mind, but it would be nice to hear from this community what else you can think of to be included in the design.
Today I will share with you the output stage of my design. This will be implemented as a module, meaning you can add as many of these modules to a power box as your heart desires (or I/O you have available).
It is a symmetrical output with some interesting features:
The same 42TL004 transformer as the MK312 is used but in a slightly different configuration. The current sinked through the transformer center tap is precisely controlled by a control-voltage (I_SET). And one of both windings is selected by the two control signals PULSE_P and PULSE_N.
This gives me two options to drive this configuration:
1.Set the I_SET voltage to control the power level and send pulse trains to the control signals. Pretty easy for software to do. I_SET voltage could even be a simple potentiometer.
2. Alternative it is possible to select a polarity by driving one of the control signals. Then generate an arbitrary wave on I_SET using a fast DAC.
Edit: Some diagrams for clarity.
Next up will be some SPICE simulations of this driver. And later I will get to the microcontroller, the communication and all the other bells and whistles.
Any feedback? Comments? Remarks? Let me know!