The relay drivers on a Megasquirt ECU use a (22v) zener between driver transistor collector and ground. The board runs mainly on regulated 5v, so saves having to have the 12v supply for the relay brought close to the driver.
OK, so the zener isn't across the coil. Your case is one I described where a zener could and would be used.
I'd be inclined to use the device made for the job, a transient voltage suppressor (TVS) such as
You're confusing me with too many choices again, what's the difference? Looks like I'll have 4 left overs.
Okay that looks like the capacitor has been replaced by the TVS.
Now it's back in the car I'm not inclined to crawl under there again for a while. I prefer the ticking of the original, it reminds me that when we were broke 45 years ago I used to mistune the radio so I could listen to the pump as rapid ticking meant I only had about 1/2 mile left to run.
Now I can't decide whether to visit next with the bike or car
AJH
These two are bidirectional so OK.
This one is unidirectional, so getting the polarity right is critical.
The article didn't use a zener. It's a bidirectional TVS:
I think that is what I said.
5p compared with 25p is indeed a lot cheaper. However, I'm not convinced the difference is significant.
It's not Peter and the TVS is what I'll be doing, especially as it fits where the capacitor is currently soldered.
AJH
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