Transistor Logic

Logic - Flip Flop module

Transistor Logic is divided into three sections: "soft" pure transistor logic, "hard" OR/NOR functions, and a CMOS flip-flop with full input-output transistor conditioning.

The soft logic section are three functions where the output voltages depend on the input voltages, so they can be used to process control voltages and even audio-rate waveforms. The OR and AND outputs operate roughly the way you would expect them to but the XNOR output provides predictable XNOR functions with hard-edged 0-5V input but when given signals other than that outputs unpredictable and bipolar results despite the module only being powered by the 5V rail!

The hard OR section acts as a comparator and produces predictable OR and NOR functions. Like the soft logic section this is done only with NPN transistors and resistors on the 5V rail.

The flip flop is not completely transistor based. The function itself is a 4013 CMOS chip because I tried building it with NPN transistors and realised it wouldn't fit on the board so I used the CMOS chip and protected the inputs and outputs with transistors because you should never leave CMOS chips totally exposed to the elements. I think this is absolutely okay and a fairly iron-clad approach because it allowed me to use the other half of the 4013 as a clock divider off the primary output.

The neat thing about all of this is that when coupled with the normaling of the Q-Bar output (aka negative output) of the primary flip-flop to its data input, the flip flop can operate as a divide-by-two and divide-by-four clock divider or if you send audio rate signals into it you can think of it as a two octave frequency divider from the Q÷2 output.

Additionally, the clock input of the flip flop is normaled to the output of the hard OR, and the top input of the hard OR is normaled to the soft XNOR, so if you just patch a signal into one of the inputs of the soft logic section you'll get a bunch of useful signals from most outputs of the module.