I've been tasked with creating a Rube Goldberg machine that employs mechanical, chemical, and electric components as a school project. I've got ideas ready for the two former topics, but I'm stuck on what to make of the electrical category. The rules of the project state that I cannot use any computers or integrated circuits, but I'd still like to have something creative and effective in the machine. I am allowed to use batteries (up to 10 V) and battery-operated motors.

The purpose of the machine is to move golf balls from their original positions to activate the next portion of the reaction, so lateral movement, lifting, and dropping are all valid options. My main concern is that I'll end up using just switches activated by the golf balls and not anything more complex or varied. Have any ideas on what I could implement into the box?

  • \$\begingroup\$ "switches activated by the golf balls" You could use transducers such as pressure sensors or light sensors. \$\endgroup\$
    – JRN
    Mar 19, 2015 at 3:44
  • \$\begingroup\$ That would be fantastic, but how would I set that up without any microcontrollers? \$\endgroup\$
    – CodeRead
    Mar 19, 2015 at 4:04
  • \$\begingroup\$ @CodeRead A phototransistor can be used as a kind of a small light-activated switch. Also, phototransistor would not be considered an IC. \$\endgroup\$ Mar 19, 2015 at 4:22
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    \$\begingroup\$ Capacitors can be arranged to explode and/or catch fire. Especially Tantalum ones. If transistors are allowed you can do about anything an opamp can do that is liable to be useful, . Motors can drive screw feeds and vertical belt lifts and "twang" flickers to fire balls. Eletromagnets can throw things and release things. Solenoid valves can supply water or air. Water can be from a tank using gravity head. And you can pump water - or air. And ... \$\endgroup\$
    – Russell McMahon
    Mar 19, 2015 at 4:42
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    \$\begingroup\$ Clever mechanical trick: A rubber drive belt over pulleys can have "trays" attached with screws into the belt - to carry balls etc. While this abuse would kill a belt when run under rated conditions you have so much margin that they can survive indefinitely. \$\endgroup\$
    – Russell McMahon
    Mar 19, 2015 at 4:44

1 Answer 1


You should look at The Cog, the video commercial of Honda, for some ideas. Aside from the fan and the windshield wipers, there is also a section there where speakers are turned on, and the vibration from the sound causes mechanical movement.

Edit: Russell McMahon gives a lot of interesting ideas in the comments to the original question. My main suggestion is to use electronic components that interact directly with mechanical and chemical components: transducers. Use these for effects such as motion (rigid as well as fluid), sound, and light. Since integrated circuits are not allowed, just use simple circuits with discrete transistors and transducers acting as switches.


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