[GreenKeys] Current loops

[Peter Gottlieb]

It’s been a couple of decades, I may have actually done this, I’ll have to go find my notes. I did something similar in the APC LineR which uses relays to select autotransformer taps; there are Zeners (and regular diodes) across the relay coils to “tune” the release to match the pull-in times. In theory this makes sense with selector magnets to keep pulse widths mechanically consistent with electrically. In practice, I’ll defer to those with experience.

Peter

> On Jun 25, 2019, at 10:21 AM, Jim Haynes <jhhaynes at earthlink.net> wrote:
> 
>> On Tue, 25 Jun 2019, Peter Gottlieb wrote:
>> IIRC something like 300 volts. You need to let the spike get pretty high to allow for rapid and nearly complete unimpeded collapse of the selector magnet field.
>> 
> But wouldn't you really rather have the current go down at about the same
> rate it goes up?  So that the delay from start of pulse to the magnet
> pulling in is about equal to the delay from end of pulse to magnet dropping out?
> 
> Of course it's complicated by the fact that we have a moving armature
> and thus a changing air gap and a changing inductance during the whole
> process.
> 
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