Edit: looks like I have a couple of bad chips, either broken or just dodgy. I replaced them with another one bought at a different store on a different day and the circuit works right.
Hi. I've been learning how to wire up this shift register. Specifically I'm using the Texas Instruments SN74HC595.
But I've had some weird behavior. The circuit had no output until I added pull up resistors to +5v on the output pins of the chip. As soon as I added these my LED array, also wired to the output, started producing the expected output. The thing is that none of the tutorials for how to wire up this circuit seem to need to do this. I've now built the circuit from scratch using new components twice and they both behave this way.
the circuit on each output pin looks like this:
chip output------- LED ---- R1 --- Gnd
|
R2 --- +5v
EDIT: I've attached a photo of my actual breadboard. Seeing as its been asked I have OE low and MR high in this setup.
The Arduino code is set up to count from 0 to 255. And with the R2 resistors in place I'm seeing the green LED's count up exactly as I would expect.