Power relay contacts, in my experience, are unreliable over time for small signals.
Much better to use signal-type relays, like 5volt reed relays in DIL footprint.
High enough coil resistances (~500 ohm) to be driven directly by an Arduino pin.
Don't forget to add a (Schottky 1N5819) kickback diode across the coil.
Leo..
Leo - thank you for chiming in - I’d hate to ask you to break this down like I’m 5 but can you explain your suggestion in more detail so I can understand better?
Are you suggesting I move to a 5v / 4-channel relay rather than a 12v / 4 channel version?
Bottom line is I want to be able to switch composite video inputs (no audio) with a momentary switch powered on 12v DC. I’m open to ideas on how to accomplish this if my original plan isn’t optimal.
No relay module, just four reed relays, like this one.
And solder them on a piece of strip board.
Leo..
It seems these relay boards you can order with a certain relay (coil) voltage, and also the trigger or input voltage specified. 5V, 12V, 24V. What writing is on the relay board resistors?
R2,R3,R6,R7 are 511 for 5V, and ??? for 12V, and 222 for 24V relays (transistor base drive).
R1,R4,R5,R8 are 102 for 5V, and ??? for 12V, and 103 for 24V trigger (led and opto).
We want 5V trigger and 12V relays, just checking if that's what you have.
This relay board is for switching power - like 10A for appliances, motors, light bulbs etc. So the relays are big and need a lot of coil current.
For video you can use much smaller "signal" relays like reed relays. They can switch only ~0.5A and be directly driven by the Nano. The coils are typically 500R for 10mA drive at 5V.
But I would get this working first before optimizing it or making it smaller.
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