Using a Diode Matrix and a Rotary Switch to Select Routes with The Octopus
This circuit shows how to use a SP4T rotary switch and a diode matrix to control 3 turnouts to make a routing control for a yard ladder. The inputs on the Octopus are active low - i.e. they change when the line is pulled to ground. The triangle symbol on the track diagram indicates which way the turnout is thrown when the control input is pulled to ground. A diode matrix is used to selectively pull low the inputs needed to throw the turnouts to select a given track. Build the circuit on a piece of perfboard. Any diodes will do - 1N4148 or 1N400x are cheap and easily available.
