At the end of Notanumber’s last post he stated that no animals were harmed during the topic under discussion & although the black & white cat that regularly shits amongst our fruit bushes could easily be in my sights, harm only became to some output mosfets.
Some while ago I emerged from the passenger footwell with the charred remains of the heater resistor pack, a crick in the neck & a pain in the arse. I would never do that again, so I built a variable control & it worked fabulously. So we’ll in fact that I uprated the demist by fitting a device which jacked the fan voltage from 12v to 18 & this too was great; until one damp morning when I asked it to work above & beyond the call of duty.
So confident was I that I was on a winner that I buried it deep behind the dash, which after the failure had to be partially stripped to retrieve the dead piece.
The failed components were mosfets & as I play with these on a regular basis I bunged some I had stock in & all was well.
Using Chinese power supplies is not always a poor idea but the ones I had about me fell into the poor category & it was only after the next stage that that aspect of their character revealed itself.
A day after I had rehomed the uprated & significantly reworked design it packed up again & after saying several words, out it came again.
I now know why but I had to power up the oscilloscope to find the problem (spurious oscillation), so by choosing a different “cat to skin” I’m awaiting a new design & I’ll report back.
M
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