Faulty supply problem

[tatus]

Tatus,
I have returned to this thread repeatedly over the last few days awaiting a final reverse engineered schematic.
I have seen it and now added my comments.
Do you think I would want to do that to deliberately mislead you, or is it possible I believe in what I have taken time to think through and present?

That was certainly not my intention, if I would doubt that you believe in what you write it would not make much sense for me to start getting into discussion with you. Did I offend you with what I wrote, then I am sorry.

Nevertheless I would like to continue discussing, so I ask you to let me stay with my different opinion for that circuit. I think it will do it's job quite well when properly dimensioned. Regarding relay control, the circuit is slow when closing the relay (~ I estimate a 100..200V/s slope) but that can be even advantageous because it may help reducing contact bouncing. On the other hand the circuit is fast when switching off, which is again what we want. Yes, adding a zener will speed up inductive discharge. But does this help increasing the lifetime of a typical printed board relay? All relays I have used have a strong mechanical hysteresis that also acts as a spring, quickly forcing the contacts open. For that reason my practice is to add a zener only when I need short turn-off latency.

Could you give me some more hints to find that post you mentioned? I had no success so far.

 

[AndrewT]

it is quicker to post than to search.

Doug Self - Muting Relays - extract from Electronics World, July 1999

 

[somejohndoe]

it is quicker to post than to search.

Doug Self - Muting Relays - extract from Electronics World, July 1999

Thanks for that Andrew. It's also in his book I believe.

http://books.google.co.uk/books?id=...+Handbook+by+Douglas+Self#v=onepage&q&f=false