I am working with students designing and building small competition robots. We have done quite well but I am having trouble with the design of a circuit to actuate a solenoid to quickly launch a 4 inch hockey puck. We are currently using an ESP to provide 24 vdc to the solenoid, but I would like to find an appropriate circuit to interface the RC receiver output to control the solenoid. The solenoid has a 1.25" stroke and rated at 12V. The coil measurements are 1.25mH at 1.6 ohms. The utimate goal would be to use 12 vdc for the system and get the absolute maximum speed and force from the solenoid (without letting the smoke out of the components). An explanation of the functional aspect of the circuit would also be valuable to the students,and me, as well. I have seen some examples that use a capacitor in a circuit, but I am open to any suggestions. Thanks, in advance, to all for your help! This is my first post!
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2\$\begingroup\$ Please provide links to the manufacturers' datasheets for the "RC receiver" and the solenoid. We need to see their electrical specifications and limits. \$\endgroup\$– Elliot AldersonCommented May 19, 2021 at 19:56
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2\$\begingroup\$ A solenoid is very inefficient as a motor, ie turning electrical energy into kinetic energy, you may want to consider other types of motor, unless of course it's the maximum 'using a solenoid' that's important. The solenoid will be thermally limited, so can be overloaded momentarily many times over without damage, as long as the duty cycle stays low. That's often the purpose of a capacitor in the circuit, to be charged up and then dump its stored energy into the solenoid. Interface from RC rx is trivial, once you have the data sheet. \$\endgroup\$– Neil_UKCommented May 19, 2021 at 20:27
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\$\begingroup\$ I have been playing with 12V solenoid door lock and surprisingly found that its response time is ONE SECOND!: chat.stackexchange.com/transcript/123411/2021/4/25 \$\endgroup\$– tlfong01Commented May 20, 2021 at 2:02
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\$\begingroup\$ Maybe consider using a gear motor to wind (or compress, or bend) a spring and then releasing it with a solenoid latch (sear-like) mechanism. \$\endgroup\$– Spehro 'speff' PefhanyCommented May 22, 2021 at 4:04
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Given limited details, I am assuming that receiver is something similar to Spektrum AR610 receiver. These types of receivers don't output high/low digital signals (at least, I couldn't find reference on how it could be configured this way). Instead, they output a pulse signal used by servos to drive servo horn position.
I doubt 12Vdc will provide enough force to quickly launch hockey puck. Suggest driving solenoid (o at 24Vdc and using capacitors to store energy required. BattleSwitch or Picoswitch allows for relay functionality from receiver channel ouput. Example schematic shown below:
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\$\begingroup\$ I am trying to get more info on the ESC and receiver we used. Based on our trials 12vdc worked well when just momentarily touching solenoid wires to the battery \$\endgroup\$– jayjCommented May 23, 2021 at 16:34
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\$\begingroup\$ When we added the ESC to act as our switch, we had to jump up to 24vdc to get a higher velocity. But it seemed like it was still slower than the direct connection. \$\endgroup\$– jayjCommented May 23, 2021 at 16:39
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\$\begingroup\$ I'd recommend measuring voltage across solenoid terminals (after steady power-on only, as voltage spikes during turn-on could damage meter) to check voltage drop due to switch. It's likely ESC and wires are causing large voltage drop. Related info link \$\endgroup\$– ErnestoCommented May 23, 2021 at 23:28