Hello all!
In the relay diagram for the constant 12V input to momentary 12V output, the diode is shown between therminal 85 and 86. If the diode is there to protect the switch from spikes when the coil field collapses, could the diode be placed in the circuit between the switch and relay terminal 86 instead of between the 2 terminals? Is this diode absolutely necessary?
Also, what would I have to do to maintain a 2-3 second backup 12V supply for the relay coil after the switched power supply is turned OFF?
Thanks!
As to your first question yes, it's generally used when firing the 85 side via the neg going aux wires from R/S and alarms and it protects their circuitry. It's not really needed if fed from a switch though I always solder one across 85 and 86 as a matter of form.
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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.
I actually did a test on my work bench with the spike or back EMF.
I was able to light up a Neon bulb with this spike.
It takes 90 vac to light an NE2 Bulb.
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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Others do it simpler - hold put your fingers across 85 & 86 when you turn the relay off.
(I was reminded the other day when testing if that loose lead on the steering column was the ground (switch) for the horn relay. It was great to hear the horn blow, but bad when it turned off!)
And those protection diodes only protect against -ve spikes don't they! (IE, they won't protect against +ve spikes. But....) Or is it the other way => +ve not -ve???
John and Peter; yes I learnt the hard way too...1974 Jag of some sorts.
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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.