WMD Geiger Counter.

[cloudscapes]

here's a design that is conceptually similar:



those 8 switches represent bits and can be dropped at will! the WMD is more complex than that (it uses a micro for some special shaping) but I'm sure you can get close with this.

most oldschool parallel DACs and ADC will probable work. adc/dacs can be found on ebay. dac0808 might be more available. and of course there are loads of parallel dacs/adcs on mouser.

[EATyourGuitar]

I want to make a box that has 8 buttons on it. do you have an easy way to get +5 and -12 from a +9v?