I’m building a defibrillator
and I want a 12v Vin 2000v Vout charging module for this defibrillator
I want to help if there is a proposal for a module to make
or a proposal for a transformer to make a defibrillator
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Hi @aymen ,
Could guess this is a subject to which no-one wants to give input due to possible legal consequences.
Will that be an internal or an external defibrillator (AED)?
You’d need a medical grade supply, probably of a flyback type.
Just curious, how are you going to test that your design works?
Cheers, heke
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thank you @heke
what are the legal consequences ??
yes external defibrillator (AED)
there are test manikins
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Hi @aymen ,
With legal consequences I mean, for example, a situation where someone gets killed due to a design flaw and it can be directly or indirectly linked to an advice on this site.
Here’s an article about power supplies for medical applications.
If your AED is battery powered, I guess toughest part of the spec is to protect the user from the 2kV (although it may seem that the system is floating, there may be a fault current flowing via patient and possibly conductive surface below).
If you plan to build your own supply, you could consider for example LT8304-1 and have a flyback transformer with roughly 1:60 ratio (or e.g. 1:(10+10+10+10+10+10)) and ensuring that the transformer has high enough isolation. See for example this:
Note that the charging time of the high voltage caps depends on the power supply. I guess somewhere 200 Joules are needed to reset a heart, thus one second charging may require supply with 2kV/200mA output, which is quite hefty. That is, first specify the allowed charging time and needed shock energy and then derive the power supply specification.
I hope this helps (no liability!), cheers, heke
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Because I live in the USA and work professionally designing electronics, I could be held financially responsible for a mistake in my advise that a jury thinks had contributed to injury or death. The size of typical awards would mean myself and my heirs would likely suffer financially for many decades to come.
Generally you should hire specialist engineers to help with designing medical devices for use in the USA. Specialist medical equipment professionals have insurance to cover mistakes preventing generational financial harm to their families.
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@heke thank you very much for all your information
you help me a lot
and I’m already testing this flyback module
but if you can explain to me how you calculate the ratio of 1:60 or (1:10:10:10:10:10:10) to get the 2000v
@PaulHutch thank you for your advice
I understand that this is a sensitive area. I’m doing technical studies and research, and after that I want to work with specialists.
Hi @aymen,
Thanks :).
I took the turn ratio from the application note I linked above (1000V output with 1:30 ratio, extrapolating that to 2000V). For flyback, the turns ratio is not critical, but some optimization is usually done to fulfill a given specs (cost, coil resistance, size, voltage withstand rating, etc.). For e.g. 2kV, would say it is safer to use a transformer with several isolated secondary coils connected in series in order to reduce the risk of insulation damage (arcing). Ensure also that isolation rating from secondary to primary is high enough. Note that certain types of flyback converters have minimum load current specification to prevent voltage run-away, i.e. need to have a dummy load at the output.
Cheers, heke