I need help making a circuit with the following specifications. Using a digital pin from a Teeny 4.1, I want to drive a circuit that charges a ~750uF capacitor. I want to control when this capacitor discharges so I can power a solenoid for a brief moment to push an object like a pinball machine. The capacitor should charge relatively quickly (anything under 0.5s). Please help. If you need clarification, let me know. (My end goal is putting on a PCB)
Did you have a question or are you presenting a solution?
Im trying to know if the circuit provided is right for my application. (and it wont blow up in my face)
At first glance, it appears incorrect for any useful application.
You might want to Google capactive discharge unit.
How much voltage will the capacitor be charged up to?
Tell us how often, per second, the solenoid will be operated. How hot can your solenoid get before it fails?
1 Kick, roughly every minute for 10 minutes. The solenoid hasn't failed yet and I've ran a couple tests using off the shelf parts and not using a capacitor.
My aim is to charge it to 36-48 volts
Could work, but it's hard to tell. A capacitor can't give much current, but with higher voltage you could squeeze some out of it. You have to test is all I can say, or run a simulation.
Just for reference, I once had a component sequencing machine with 24 stations, each having a 24 volt rotary solenoid to cut component leads. Each solenoid was powered at 120 volts DC using a capacitor discharge. Each solenoid could cycle about once every second. No, I don't know the capacitor values.
Seriously? Capacitive discharge is used for spot welding.
Discharge current is limited only by the wiring and ESR of the capacitor, so choose wisely.
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My guess is that 750uF is too small and will discharge before the solenoid can move. Have you tried it? If the solenoid is "almost working" the capacitor might give it enough boost to work.
You'll also have to take care charging it. It will take lots of current (if it's not limited) when it first starts charging. The voltage will drop momentarily and it could damage the power supply and if the power supply is shared with the Arduino, the Arduino might "glitch" (crash or reset).
Capacitors are great for short-term current bursts but they make lousy "batteries" because they discharge quickly before leveling-off as they discharge closer to zero. This is the opposite of what you want from an "ideal battery". An ideal battery would hold its full-voltage until it's discharged.
I haven't tried using a capacitor yet. I want to use it as a short turn burst. However, I want to control when to charge it and when to discharge it. I definitely dont want to have any voltage drops.
Very likely. I use 2200uF in a 16V CDU with a very lightweight solenoid, and 10000uF in another 6V CDU that uses a beefier lock style one, like the one shown below.
I've used capacitors to give peak discharge currents of over 5kA.
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I was talking about the cap actual in this thread, sorry I expressed it as caps in general.
Is there actually a circuit posted here that I can't see? Otherwise, yes, what you suggest is possible: I've done it before, and for the same reason. But I don't really know what question you're asking.
IIRC, I used a Cockcroft-Walton voltage multiplier driven by an ATTiny85 to charge the cap to about 60V before dumping charge into the solenoid
I need help making the circuit
Actually I remembered wrong. It was a standard inductive boost circuit. I'm not big on videos, but some people find them helpful: https://www.youtube.com/watch?v=yrO58gdByu8
You haven't provided enough information to make a circuit. To start with, provide the voltage, current and winding resistance specifications for the solenoid, or a link to the data sheet.