A display on top of the multiplexer shows which of the 8 outputs are activated.

6 diodes (AN 4002)
6 relays (2 RT">

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	3/8 RCX Output Multiplexer by christophe-masclet@noos.fr This home-made device controls 8 Fischer-Technik solenoid valves from 3 RCX ports. This is an easy-to-build RCX output multiplexer. For the first time in my life I’ve build an electric circuit. Definitely LEGO is a good way to learn science! How does it work ? The F-T solenoid valve is an electric to pneumatic controller. Like the LEGO pneumatic switch it controls air-flow in a pneumatic circuit. A display on top of the multiplexer shows which of the 8 outputs are activated. I develop it to pilot my future 6-legged pneumatic walker. Port  A Port  B Port  C Multiplexer display 0 0 0 1 2 3 5   +9v 0 0   2 3 5   -9v 0 0 1 3 5   0 +9v 0 1 2   4 5   0 0 +9v 1 2 3   6   0 -9v 0 1 2 3 5 7 0 0 -9v 1 2 3 5   8 What do you need ? 6 diodes (AN 4002) 6 relays (2 RT, I used 6V ones but 9V should be better) 8 numeric displays 8 resistors for numeric displays Resistors depends on how many leds are activated on each numeric display : 1 : 2 leds R1=225 ohm  5 : 5 leds R5= 90 ohm 2 : 5 leds R2= 90 ohm   6 : 6 leds R6= 75 ohm 3 : 5 leds R3= 90 ohm   7 : 3 leds R7=150 ohm 4 : 4 leds R4=112 ohm  8 : 7 leds R8= 64 ohm   Also by Christophe: Previous Home Home-made One-way Valve Home-made Air muscle