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Extremely simple, and light weight DC motor controller.

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iflymyhelishigh

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Hi guys. I am currently out to build a VERY SIMPLE and VERY LIGHT WEIGHT DC motor controller. Currently, I am trying to build a hovercraft for a school project. This hovercraft should be able to go in a straight line, and run off 2 double A batteries. I am sort of loopholing this idea, and running the hovercraft off a capacitor, thus lightening the load.

My circuit, a very simple one, uses a

1: 3 volt DC motor
2: 20F 3.7 volt capacitor
3: simple toggle switch

These parts work, but the problem is the capacitor discharges too fast for my liking, and that the motor vibrates at a high RPM, thus throwing the hovercraft off course. I do not know where to get a bigger capacitor, but I think that the main need is I need a PWM circuit, as simple as possible.

Thank you, iflymyhelishigh
 
A 20F capacitor discharged from 3.7V down to 1.7V is only equivalent to an 11.1mAh battery (about the same as a small button cell), an AAA NiMH cell is typically 1000mAh.
 
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Hmm... Capacitors are at least 3 X as less weight as a standard battery.

Now, I am going to hook up 3 or more in parallel to try and increase capacity.

This race is for speed, and I feel that a capacitor will give me the speed I need.

I will try building that 555 circuit.
 
3x less weight as a standard battery?

I'd say it's much less than that.

How much current does the motor draw?

What's the internal impedance of the capacitors?

Are they memory back-up capacitors?

If so they'll have probably quite a high impedance, too high for what you want.

If it's 1A expect a couple of minutes at most from the capacitors (assuming a total of 60F) where two AA cells would last a couple of hours.

If you want to cut down on weight, why not use smaller batteries?
 
I bought my brother a toy helicopter.

The helicopter charges from the control unit which requires six AA batteries.

The helicopter has a built-in Lipol 3.7V 50mAH cell which is 20mm² and <5mm thick and is very light.

The Lipol cell is much smaller than the amount of supercapacitors you would require to store the same amount of energy.
 
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