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+--- Thread: Smart Diode cut out (/showthread.php?tid=4662)
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Smart Diode cut out - JonE - 13-07-2020
anyone using these? I realise they are just a slightly marketed version of the cheap single diode we can all buy to replace the cutout, but it's good that they are being marketed like this:
https://www.themagnetoguys.co.uk/smart-diode-cut-out
RE: Smart Diode cut out - Ian McGowan - 13-07-2020
Here is an alternative solution of similar ilk:
RE: Smart Diode cut out - JonE - 13-07-2020
It was you, Ian, that recommended that and helped when I tried it on my first car. And I've just excavated the one I wired up to dust it off and use! Couldn't find the diagram you have just posted, so thanks.
It is quite interesting reading back through the old forum on charging alternatives and keeping the ability to be "the fixer" when adversity strikes. The Speedex hasn't got a PLC or a Lucas cutout, so its an obvious candidate for doing this now, with the ability to carry a light, cheap spare for easy swapout.
RE: Smart Diode cut out - jansens - 13-07-2020
It's not the same as the normal diodes, it's probably one of these. Designed for use in solar power applications: https://www.ti.com/lit/ds/symlink/sm74611.pdf?ts=1594664137052&ref_url=https%253A%252F%252Fwww.google.com%252F
Clever little chip really. Quite cheap, in NZ the chip is only $6.40 (about 3 quid). If anyone has one of the boards from the Magneto guys they can check the number.
Simon
RE: Smart Diode cut out - Ian McGowan - 13-07-2020
If you want to keep a spare in the cupboard, Jon. These are as cheap as any, £2.79 inc postage.
https://www.ebay.co.uk/itm/KBPC2502-Bridge-Rectifier-Diode-25A-200V/282555840523?epid=10004560592&hash=item41c9a3f80b:g:y~AAAOSw8d5ZWsIu
RE: Smart Diode cut out - John Cornforth - 13-07-2020
I wasn't previously aware of those Texas devices, which seem to have a much lower forward voltage drop than either an ordinary Silicon rectifier (Typically 0.6 to 0.8 V) or a Schottky Diode (Typically 0.4 to 0.5 V). This would be especially useful for a 6 volt system, and would probably make heatsinking unnecessary.
RE: Smart Diode cut out - Bob Culver - 13-07-2020
Thanks all, esp Simon, although I always maintain eelctronics are not in the spirit of Sevens (despite having some quite lofty albeit long forgotten qualifications!)
A mechanical cutout draws current which is wasteful. But as pointed out a normal diode absorbs voltage which is equallyo undesirable or worse. I suppose the unit will survive the enormous ignition hash present in many Sevens.
RE: Smart Diode cut out - JonE - 13-07-2020
So from the comments here, I detect it could be more efficient... but is it less inherently stable as a chip than a rectifier? I was thinking of placing two rectifiers in place on the bulkhead so in event of failure the wires can just be swopped over. But presumably as you clever guys start researching the newbie chips, those are going to be equally cost effective.... if they aren't 'fragile'.
RE: Smart Diode cut out - Bob Culver - 14-07-2020
Wheter a failed cutout or diode never really any need to be totally stranded, as long as engine not idled for ages, and battery disconnected when stopped. If fails open circuit must be brideged, assuming the dynamo survived.
RE: Smart Diode cut out - Zetomagneto - 14-07-2020
Jon, you don't have a rectifier on a dynamo charging circuit.Rectifiers are for alternators among other things. What are you wanting to do?