Transistors

[Rihards Veips]

Is there a way to multiplex transistors[NPN] like an LED cube?{With an Arduino} (Can't figure out how it would work with transistors)
       I need that for my lighting project to drive ~64 relays     o-o

[3x3x9 Transistor Tower]

[Simon]

err 3x3x9 is not a cube.

You give practically no detail of what you are trying to do. how do you want to control it ? this sounds like a need for an mcu driving a multiplexer driving a bank of latches

[Rihards Veips]

I think I figured it out - I connect all the BASE pins in collumns and the collumns on the output pins of the Arduino    then connect the COLLECTOR to the GROUND pin on the Arduino   And if I am using a different power source for the relays I connect the negative to the ground of the transistor and the relay input to the EMMITER and the positive to the relay with a diode and a resistor.

[mariush]

I don't understand what you're trying to do. I don't know what you mean by relays.. if you mean the classic mechanical relays, those aren't really designed to work like leds, to be turned off and on several times a second (not to mention it will be very noisy)

If you want to make a LED cube, here's some videos that might help you out:  https://www.youtube.com/playlist?list=PL0JWuCHXfJ2zXVRqFRFVq-lNt_xtCYMjx

In some of those videos he explains the theory behind it, the circuit, everything.

[David_AVD]

If you only want one relay on at a time, you could multiplex the drives in theory.  In practice I doubt if would be worth it due to the extra diodes required to stop the interaction between rows and columns.

Just use 8 octal driver chips such as the UCN5821.  They can drive the relays directly, have the back-EMF diodes inside and can be cascaded to simple serial control.