Hacking Tens – How to Create a DIY Controllable Tens Unit for Pattern and Intensity Control

I need help or a tech partner.

Use this info at your own risk makers. I am hesitant to design and post a schematic and code because of liability. But there are enough hints here to get you going.

Tens Facts:

  • TENS units (at least modern ones) use an asymmetrical biphasic square waveform… Not a standard square wave.
  • intensity (output) usually adjusted by 1mA each step from 1 to 80mA.
  • general off the shelf modes of options: B(Burst), N(Normal), M(Pulse Rate Modulation)

I have a chronic TMJ pain issue. I have been using a TENS machine for a few years. I have found that I get a good response from low intensity(voltage), small pulse width output.

It may sound strange, but my pain is not constant and I can get waves of dull pain. The various machines I have used all have patterns of various different types (crescendo-decrescendo, slowly increasing etc…)

To program unique patterns.

I think we first need to build a step up converter and then use the Arduino to control it via the current at the base of the transistor Q1 in the diagram that I included.

Good step up converter tutorial http://www.instructables.com/id/Arduino-Buck-Boost-Converter/

$6.95 $8.68 $8.26

Based on this attached Schematic an Arduino forum maker “DC42” say he would connect to the Q1 and Q2 inputs. Turning on Q1 will allow the 80V to pass to the electrodes and turning on Q2 would short the electrodes to ground. Never turn them both on at the same time! This is a totem-pole configuration. Turning them both on at the same time would short the 80V directly to ground, and blow things up.

So you would apply your PWM signal output from the Arduino to the Q1 input, and the inverse of your PWM to Q2. This will modulate and shape your 80V waveform.

Everything else is controlled by Arduino Sketch Code by altering the frequency, pulse-width, and turning the PWM on and off for your patterns and durations.

We could also build a step-up converter from modern and more efficient components (recommended).

WEBENCH® Power Designer

http://www.ti.com/design-tools/webench-power-design/power-designer.html

Check out the SwitcherPro tool

https://focus.ti.com/docs/toolsw/folders/print/switcherpro.html?DCMP=hpa_tools&HQS=Tools+OT+switcherpro

Maxim has a similar tool to design a switching power supply.

Credit-

http://forum.arduino.cc/index.php?topic=158242.0

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