Classic 200 Aux output relay/diode?

[cybermaus]

Or, a zener diode of something less than 100V or so.  A Zener will help the relay to turn off faster rather than having the current keep flowing in the inductive loop of the diode and relay coil.

Not sure I understand that trick?

Should I place the zener  series, so that when the spike flies back, it will still not allow any current flow (thus stopping the coil faster) but the voltage is now divided over 100V for the zener and the rest for your 200V fast diode? So effectively raising the protection from 200V to 300V? Would a simple normal two fast diodes not do a better automatic 50/50 division?

Please (at your convenience) confirm/explain for knowledge sake, but I do not think fast switching is that important. I'll go with he classic proven diode.

Edit: Aha, like described in this document
Cool. Learned something today 

[vtmaps]

You will want to add a "cache diode"  (or is it "catch" ?) across the relay coil

I think its "catch" diode.  Also known as "snubber" or "flyback" diode, I think.   --vtMaps

[boB]

I would just add a regular diode.   What a zener can do is to let the voltage fly up to the zener voltage
and not let so much current circulate through the normal diode and the inductance of the relay coil.

It is a speed-up trick so not probably necessary for this application.  Also, if using a zener diode,
it will dissipate more power because the voltage drop is higher than a normal diode.

Yeah, just go with a regular diode.

I couldn't remember if it was cache or catch.  I somehow remember the word cache but it's been many years since I've had to remember, so I just don't think about it.  Snubber works too.

boB

[dgd]

And about that relay protection?

I guess if I cannot get a good answer on the matter, I'll take your and @dgd's practical claim he has never had it break anything despite numerous relays (though his remark a relay coil cannot send a significant spike is a bit uninformed)

Hmmmm....  I still think a snubber diode across the coil connections of the relay is not necessary.
If the Classic was likely to be damaged by any form of switching voltage spike then I'm sure the Classic manual would have recommended the use of such a diode when using AUX1 to enable a mechanical relay.
Also, I would expect the spec sheet for the relay would also recommend such a diode or other device and provide a wiring example and diode type/spec.
Often the relay manufacturer will actually install a diode if they know their relay design is likely to cause such a switching spike or excessive noise/ripple.

So there is nothing in the Classic manual in the AUX section and if there is nothing about snubbers in the relay specs then why bother with the effort to install an external diode?

just IMHO

dgd