Flyback Diode help?

eagletalontim

I am finishing up the design for powering my Prop in an automotive environment, but have a question about determining what diode to use to prevent flyback voltages from other devices that could cause my circuit to possibly restart or act different than desired. most users have standard automotive relays connected to a common 12V wire from the ignition and also connect my device to this same circuit. I am needing to install a protection diode and possibly a capacitor to help prevent any issues. I do not have any specs on what the relays are rated at, nor any idea of what kind of "flyback" voltage may be present when a relay is switched off. The standard voltage is from 12V to 14V. Amperage draw of my device is roughly 3 to 5 amps when it is activating other components on the vehicle.

jmg

If you are not providing both side of the relay, then a common approach is to use a Zener clamp instead. (18-24V)
That does not care so much about the +ve relay terminal and gives you protection from ESD events in either direction.