I'm building a digital modular synthesizer where I use a Teensy 3.1 for the control interface and each module has a 74HC595 and a 74HC165 shift register and a CD4051 multiplexer. Here are their datasheets:
I don't know much about electronics and I'm facing some issues which I think have to do with power supply. I've put 14 modules up to now and I'm using a voltage regulator giving 5V/3A http://grobotronics.com/voltage-regulator-lm1085it-5v.html which I feed with a 12V/2A DC power supply (that's what I have at home as I'm trying out different things). I've measured the current of the whole circuit with my multimeter and it said that it draws around 100mA, but again I'm really not sure if this is the case. The thing is that, with the said power supply, the circuit seems stable with up to 11 or 12 modules. After that I get some strange behaviour where some LEDs are dimly lit when they're supposed to be off and I receive some data in my computer which should not be there. Mind that I pass all data and power supply from one module to the next with ribbon cables like this http://grobotronics.com/ribbon-16wire-1m.html. I think that 3A cannot pass through such a thin cable, right? But still, I think that 3A are a bit too much for this circuit.
I'm powering the Teensy with a different power supply with common grounds.
Any advice as to how much current can these ICs draw and how I can overcome my issue will be greatly appreciated.