Re: [buildcheapeeg]Patient Safety and Isolation Transformer

From: Jim Meissner (jpmeissner_at_mindspring.com)
Date: 2002-01-13 19:55:24


Dear Joerg:

All of the inexpensive Brain Monitors, that I am familiar with, use batteries "only".

You stated that your preference would be "not" to use batteries.

I suggested that we give the customers a choice of using batteries or a transformer.

I offered to help you find a "safe" transformer. A medical grade transformer is quite expensive.

My company manufactured transformers for a few years and I know how they can fail unless a lot of special care is taken. There are "safe" transformers commercially available. If you want me to, I can call an old customer and find out the manufacturer and part number of a transformer we used in a high meg ohm wheatstone bridge circuit. It would work well for this application. Also there are filament transformers made that are used in high power RF transmitters that have the high voltage capability and low interwinding capacitance. These would be 50/60 Hz transformers.

On the other hand you seem to be interested in high frequency transformers.

> ...Normally the
> primary and secondary are wound on to of each other. The picture you
> sent shows that the design of your DC/DC transformer is very good.
> It would take several layers of tape under each winding and vacuum
> impregnation make it really good.

> So this could be a safe option ?

Yes, if done properly.

> I have just emailed traco power products, the manufacturer
> of the tmv-en DCDC converter series, if their TMV-EN DCDCs are
> IEC601-1 compliant.

> Perhaps the pcb layout could be done in a way, that alternatively
> for battery operation a LDO could be used, and for DCDC powered
> operation a TMV-EN DCDC.
> So each user could decide what degree of safety he needs.

Yes, that should work.

Juergen P. (Jim) Meissner
Check out my Website at www.MeissnerResearch.com
Read about the benefits of the Brain State Synchronizer sounds for improving your life and health.



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