[sdiy] 3 position switch help

[JH.]

>It's a bit convoluted - but you can make a SP3T (ON/ON/ON) toggle switch 
>from a standard SPDT (ON/Centre-Off/ON) toggle switch >using OR Gates on 
>Pins 1 and 3 of the switch and a NOR Gate on Pin 2. These 3 gates then turn 
>on/off 1 of 3 analogue switches - like a >4066.


Oh, if you can use analogue switches, you only need a single gate, when 
using an on - off - on switch:
Pin 2 goes to vcc. Pins 1 and 3 get a pulldown resistor to GND, and control 
a 4016 directly (A, C).
The mid position (B) is decoded with a single NOR gate from pin 1 and pin 3:
B = notA AND notC = A NOR C = not(A OR C)
A 4016 contains 4 switches.
You need 3 for the analogue switches, so you can build an OR function from 
two diodes and a resistor, and use the 4th 4016 switch and a resistor for 
"not".

So you just need a single 4016, two diodes, and a few resistors.

JH.