Let's Make Robots!

hovercraft circuit

hi there reader, i would like to build a hovercraft. but since im not so experienced with setting up the construction i would like to hear if my circuit i build is correct, and if it is not, what should i add or remove and dont forget the why. (please also read info below img)

would this work. here is the construction:

- 2 motors in serie wich are the motor who serve for the floating

- 1 back motor to draft the hovercraft forward (just a on/of-construction)

- and at last aservo wich is the back motor sittin on to turn right or left when the servo moves


now i will use cpu-fans as the motors in my circuits. im just not sure about the power i give, is it enough? or it far too high that i can dammege somthing by burnin it? or did i use my diodes and capisitors right to avoid this situation?


thnx alot


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so this is what i get, how about this circuit? would this be ok?

somone told me about puttin a diode anti-parralel on the transistors? help me out plss thnxxx alot nick


Your schematic makes a lot more sense :)

Just make sure the tranzistors can handle the current. I use Darlington tranzistors such as TIP120, TIP121, TIP122. They are a bit beefier than necessary and mine had integrated protection diodes (which is not really necessary in the case of CPU fans because the brushless controller in the fan already includes the diodes, they are only needed when driving inductive loads directly, such as brushed motors or solenoids).

I hope you don't plan on having 3 packs of 8 AA cells each, that's going to be a bit heavy. You can probably get away with just one pack powering everything. Also, if you don't need to switch the two "floating" motors individually you can use one tranzistor for both of them (but keep them in paralel to eachother).

The rezistors (R1,R2,R3) should be between 150 to 500 ohm, depending on the tranzistor you choose. I would go with 220 Ohm.

I agree with Antonio's comments. I'd add that if the weight of the batteries becomes an issue, you can look into LiPo or NiMH racing packs, which will have a lot of power in a lighter package.

Good luck.

well, i've been told that cpu fans may not be powerfull enough to let the whole thing float. so maybe i should get sometin else, what do u think what part would serve great as a preasure-building-"fan"? and about the diodes can u teach me how i should have placed them when i was using diffirent kind of motors?

I wouldn't always listen to what other people say, although they may be right in this case. Before you go and buy model aircraft engines try some things out: Try putting your fans on top of eachother, does this increase the static pressure they produce? Try increasing the surface of your hovercraft (the lifting force is equal to the pressure multiplied by the surface). Try increasing the voltage to the fans up to 14-15 volts, do they speed up significantly? (but don't do this if you are not prepared to fry them :) ) After you have tried all this you can go buy a cheap flying toy and reuse its motors. Get one with at least 2 motors. Like an XPV. See if you can find cheap chinese knock-offs, it would be sad to ripp out the motors from a brand new toy.

Have you checked out the successful Hovercraft robot already posted on LMR?

yah ofcource ^^

Didn't you see me post that already Al?

Missed that, Zekk. My bad.

Missed that, Zekk. My bad.