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need to design a square wave generator for a medical application, 2 Hz, can I use an 555 timer or an aruduino nano and an AD9833?

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Nov 30, 2020
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This project is to develop an electrical stimulation device that sends square waves to electrodes taped on the ski and should alternate between a 2 Hz square wave and a 100 Hz square wave. Each will run for 3 seconds, and should stop after a fixed amount of time. The device with include a dial or similar control to set the current.

Your project resembles a two-tone siren as seen in basic circuits for 555 IC. Possibly a 556 (which is two 555's in one chip).

To operate for a fixed length of time, possibly an additional 555 acting as a one-shot.

What is range of Current you have to control ?

Regards, Dana.
--- Updated ---

One possibility, single chip. Very little code needs to be written, I estimate <
10 lines of code.

The SAR measures pot and uses that value to set current source.. All that you
see is onchip.

A more advanced version of chip has all of the following, including DFSP Filter
in case you need to filter signal of interest.


Other chip resources in 5LP family, the above was lower end 4 family. Which is a subset of
following -


Regards, Dana.
--- Updated ---

Another approach using mBlock to program an ATTINY85. You start with
and Arduino Nano board, ~ $3, and then once debug finished you use the
Nano board to program an ATTIN85 (8 pin dip).


mBlock, free, 6'th graders using it to program robots, but a fast way of doing simple
control project.

The pot is examined by its A./D and then used to program its PWM. You then add a R-C
LPF to convert PWM duty cycle back to DC, and use that to control some external OpAmp
constant current source/sink.

Regards, Dana.
--- Updated ---

Here is proto using ATTINY85, after being programmed with Nano Board.

In this case you have to take PWM DC V (After LPF) and feed that to external
OpAmp current source/sink.

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