Solenoid Based Shutoff Switch

thingiverse

I created this simple device as part of my larger Minivac 601 Replica project. The Minivac 601 is an electro-mechanical computer from 1961, detailed on Wikipedia. This Thing also relates to my Mostly 3D Printed Rotary Switch. The Minivac 601 has a sixteen position rotary switch used for manual input and as an output device. You can see the panel containing the switch in the photo below. To accomplish the output function, the rotary switch was motor driven, something I'm currently working on with my replica. The motor is powered by applying power through the eyelets labeled 17 and 18 using patch wires to create the circuit. The polarity of the wires determines which direction the rotor turns. There's also the ability to stop the motor by creating a circuit between eyelets 18 and 19. On the original Minivac, this was done by shorting out the motor. The circuit diagram below shows how it was accomplished. For my implementation, I went in a different direction, leading to this Thing. I had a 12 V solenoid on hand along with extra magnetic reed switches and magnets from the Rotary Switch project. The idea is simple: when the solenoid isn't powered, a small magnet is positioned near the reed switch, enabling any circuit connected through it. When power is applied, the solenoid shaft retracts, moving the magnet away from the reed switch and disabling the circuit. For the Minivac, the motor will be wired through the reed switch to implement the stop function. I know I could have accomplished this in many ways – with a relay for instance – but this approach makes good use of parts on hand, feels in keeping with the overall Minivac vibe, and was fun to do.