Transcutaneous Nerve Stimulator Circuit

Transcutaneous electrical nerve stimulation (TENS) is a term typically referred to the use of nonpharmacologic or noninvasive kind of treatment for neutralizing superficial pains.

How  Transcutaneous electrical nerve stimulation Works

Researches have shown that TENs helps to control pain both over peripheral and also central mechanisms.The central mechanisms include areas of spinal cord and brainstem that are known to incorporate opioid, serotonin and muscaranic receptors which could be effectively stimulated using TENS implementation.

Across peripheral areas TENs may help induce analgesic effects on receptors such as opioid and alpha2
noradrenergic.

The process involves application of very low DC low frequency pulses through electrodes on the patients skin surface for activating the intended pain control.

The method could tried by applying different frequency ranges from as low as 10 Hz up to 50 Hz.

The circuit may be tried with on two modes  the first being in the sensory intensity mode where the patient is able to feel strong effects but without motor contraction sensation, and the second is through high intensity mode in which the motor contractions are induced but without any relative pain or strong sensations.

Typically the high intensity mode is implemented through a high frequency stimulation while the motor intensity is done through a relatively lower frequency electric current.

However researches have indicated that the analgesic effects may be released through any of the above modes regardless of the frequency intensities or variations.

To be more precise, a low frequency TENs may be responsible for initiating the μ-opioid receptors in the spinal cord and brain stem, while a higher frequency TENs could be used to give rise to the activation of δ-opioid receptors around the same areas.

Further developments suggest that the application of TENs may effectively relieve pain due to the actions of serotoninergic, noradrenergic, muscarinic, and γ-aminobutyric acid (GABA)-ergic systems
on the analgesia with the application of both low or high frequency TENs on a patients skin.

A simple Transcutaneous Nerve Stimulator Circuit may be witnessed in the above figure, using the work horse IC 555 configured in its standard astable mode

P1 is used for producing several ranges of frequency outputs in conjunction with a variations in the pulse widths of the output frequency for the implementing the above explained TENs procedures  T1 is used for producing TENs at the level of the supply voltage for acquiring maximum effectiveness.

The transformer could be any ordinary radio output audio transformer or made by winding 10:100 turns 36 SWG super enameled wire on a small EE ferrite core.

The output of the transformer could be arranged in the form tiny protruding copper prods, not too sharp but sufficient enough for creating a slight digging impression on the skin and may be wrapped on the affected area with some suitable cohesive band.

2) TENS Circuit for Multiple Nerve Stimulation

The following circuit was requested by one of the dedicated visitors of this blog, as given below:

"I am looking for a circuit solution to perhaps utilize  a pair of bar/dot graph display IC's and to take each triggered output and transform this output to a voltage sufficiently high to stimulate nerve endings .

The nerve endings are connected via a conductive needle ( stainless steel)  making intimate contact with said nerve endings. I have suffered by convulsive 'jumping' of my legs when I relax and when I am in bed.

I have been to a number of specialists without them being of any assistance. I have been reading about T.E.N.S. and believe that this could be worthy of an experiment. There are apparently many people world wide suffering from this complaint.

My thoughts are that if I feed a variable signal of low amplitude into the  nerve ending that the continual low stimulation might override the large pulses which cause instant muscle contraction. I believe that this is worth a try."

Circuit Diagram

The circuit is based on a simple IC 4017 and IC 555 sequential dot mode driver circuit. The output of the IC 4017 create a running or sequencing high logic pulse across its 10 outputs in response to the clocks generated by the IC 555 astable at its pin#14. Each of these outputs are configured across a transistor/inductor circuit which act like a small boost converters, and convert the 9V pulse into a low current 100V or 120V short pulses.

The indicated ends could be integrated with 10 individual needles for the required transcutaneous stimulation across the intended muscle areas.

The pulse width and frequency can be controlled by adjusting the 100k preset.

Warning: The coil dimension and voltage presented above are assumed values only, and have not been confirmed. Serious experimentation may be required through qualified medical engineers before implementing the device practically.