I am currently playing around with an 8 channel solid state relay board, and i'm trying to make it work with fewer wires. For that, i've come across SIPO shift registers, more specifically the 74HC595.
From what I can gather, this register can translate a byte into 8 separate 5v signals, 10mA individual and 70mA combined max.
The SSR board is your typical bog standard cheap thing from ebay. Fairly basic, below 2.5v it switches to off, above 3.3v it switches on, has a 2mA trigger current.
So one would say there has to be a way to make this work, but apparently its not quite that simple. Ive used the sample circuit found here, along with some of the code. I've replaced the LEDs with the relay channels, and the resistors are 220ohm. The whole thing is powered from a 1A 5v power supply. Ive also put a capacitor on the latch pin and one on the power going to the register to try and get it a clean feed.
But for some reason I just keep getting incoherent sputtering from the registers channels. When I have the byte turn on channels one by one, it works up until 4 or 5 and then it just quits. Ive measured voltages everywhere and it all seems fine. Direct connect controlling it from the arduino works, so the board is not faulty. I feel like I'm messing something up here, but I have no clue what.
Does anyone know of a working example of how I should be doing this?