Transcranial Magnetic Stimulation project - part 1

Transcranial Magnetic Stimulation (TMS) is a technique to stimulate brain tissue directly through the skull. It works by sending a very high current pulse through a coil that is located on the subject's scalp. The fast-rising edge of the pulse induces a current in the brain tissue, causing neuron stimulation.

This device uses a capacitor bank, high current SCR, trigger circuit, figure-8 (or butterfly) coil, and high voltage charging circuit.

Link to the SCR datasheet: http://www.5scomponents.com/pdf/5STH_30J4501.pdf

Some good technical information: http://www.abovesobelow.com/TMS/cTMS.pdf

Wikipedia: http://en.wikipedia.org/wiki/Transcranial_magnetic_stimulation

Category:

Science & Technology

Tags:

• TMS
• transcranial
• magnetic
• stimulation
• di/dt
• scr
• coil
• figure-8
• capacitor
• discharge

[Transfusions]

Do we have any other method from using SCR?

[bkraz333]

@Transfusions A bank of MOSFETs would also work and allow the current to be stopped before the capacitors have discharged.

[pgqneto]

Congratulations! I've been researching about how to build my own TMS stimulator. what is the clamp on the SCR for and how much did you pay for it? is it possible to make rTMS, like 20 pulses per second?

[bkraz333]

@pgqneto rTMS should be possible, but I don't want to try it myself. It would need a much larger capacitor bank, and a MOSFET or similar switch that can be turned off mid-pulse.

[pgqneto]

@bkraz333 Thank you Sir. Do you know what is a pulse capacitor? I saw a video of a guy that is launching a washer with an old Magstim. He sent me pictures of the Magstim inside. It uses two 50uf/5Kv General Atomics pulse capacitors. they must be very expensive.

[bkraz333]

@pgqneto It sounds like marketing jargon. Use any low-ESR capacitor with sufficient capacitance and voltage ratings.

[Films4You]

Electroconvulsive therapy by another name, an electric current is induced in the brain by these systems

[bkraz333]

@theemusic92 The most dangerous aspect is the charge stored in the capacitor bank (can cause a very nasty shock). Single-pulse TMS has been done on humans for decades without any lasting effects.

[TeravoltOrg]

I like your SCR clamp

[bkraz333]

@pgqneto These hockey-puck type SCRs require external clamping pressure to operate properly. I am using a woodworking clamp, which is probably barely adequate. It should be clamped down with heavy bolts -- the datasheet lists a minimum and maximum clamping force.