Michael,

The sad thing about kitchen table programmers is that most that make them should not. A programmer is a very advanced piece of electronics as far as meeting certain standards. Many kitchen table programmer builders do not own an oscilloscope, how do they know the width of the pulses when they use another PC, another Windows version, another power supply and another chip than the designer of the circuit.

I have no doubt that you can make a programmer that works for the chips you have set it to program, I have very little confidence that a beginner with a chip you have not included in the repertoire of your device will program correctly.

Erik