You are viewing a single comment's thread from:
RE: Custom 28 Relay Controller Board for Raspberry Pi 3
COOL! Your power problems can be resolved by powering the relay with a separate power supply. You may also need some kind of photodiode isolation to protect the pi and ensure 100% on/off functionality for all 28 relays. Are these solid-state relays? I've had the non-solid-state analog ones fail after a few thousand switches and only use solid-state now. Where did you buy it?
The Pi does not have a problem with the power with all 28 relays powered on, and the chance of having more than 1 on at a time is pretty slim in normal operating conditions. They are non-solid state relays, but the load is not going to be big, so they should be just fine. It is a custom design, not commercially available.
So what's the problem that causes you to only be able to use 25?
When powering on/off the Pi the GPIO pins 2, 3, 14 change state temporary... switching on and off the relays on them.
I didn't understand it!?
OIC, the only solution for that is to invert the signal at the hardware level. Such an inverter can simply be built with a single transistor and two resistors, or you can use a chip with six of them, like a 74HC04 (powered with 3,3V).
ঈত
it is too much costly here in Bangladesh!!