Re: Master Clock contact spark quenching
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In the pipe organ world, the use of diodes in direct electric actions is standard practice. I have just fitted up a direct action unit extension organ with about 200 electromagnetic valves, each runs on 15 vdc. and carries a current of about 250mA. Each coil is shunted with 1N400X diodes or equivalent. There is no sparking - imagine if there was, the organ woiuld break down every day as the coils are activated hundreds of times with each performance! The diodes cost about €1 per 100.
The point about polarity is, of course, valid but simply solved by using a high current silicon diode in series with the power supply. If connected the correct way round, all works well; if the wrong way round, it doesn't work at all, so it "fails safe".
From: John Hubert <jfphubert@...>
Sent: Thu, 7 Jan 2021 11:17
Subject: Re: [synchronomeelectricclock] Master Clock contact spark quenching
I do just as you suggest on all my dials and masters. 1N400X series diodes. The maintaining of current is minimal (looked some years ago with an oscilloscope and it was insignificant). There is typically some variation of impulse length dependant on the master anyway (Gents tend to be longer and early Synchronome clocks rather short - lighter parts?). Typically, the coil carries about 300 mA and has a resistance of about 5 Ohms, with a parallel resistor of about 50 Ohms.
Diodes work well - but of course you have to have the right polarity.