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Topic: h-bridge for toy helicopter motors (Read 2998 times) previous topic - next topic

erichbschulz

hi,

I'm wanting to do some projects with the kids using some motors extracted from some broken toy helicopters. (I have 3 dead helicopters, so that is 6 motors plus the 3 tail rotors)

I cant find the specs anywhere but the copter is is powered by a 3.7v Li poly battery (so there's a hint)

this looks like the item
http://www.ebay.com.au/itm/Motor-B-For-Syma-S107G-S105G-RC-Helicopter-Spare-Parts-S107G-17-/271432635766?pt=LH_DefaultDomain_0&hash=item3f32a55576


I was thinking these mosfets would be a good match (from a basis of profound ignorance):

http://www.ebay.com.au/itm/10PCS-IRFZ44N-IRFZ44-N-Channel-49A-55V-Transistor-MOSFET/281489812303?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20140106155344%26meid%3D76b234ed881d4e449a36588a1ae8369a%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D271618220092&rt=nc

but would I be better with a h-bridge so I could get forward and reverse?

is so any tips on what I should order?

many thanks in advance

Erich


erichbschulz

actually these look like they would be suitable?

what do you think?


Isaac96

#2
May 23, 2015, 10:44 pm Last Edit: May 23, 2015, 10:46 pm by Isaac96
Start by measuring the current drawn. If it is less than 600mA, you can use a L293D.
How big are the motors? Are they brushless? How many wires coming out of them?
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erichbschulz

Thanks for the tip Isaac

I'll measure the draw when i get around to extracting them.

they are two wire - dunno about brushes

Isaac96

Two wire normally means standard DC brushed motor. The L293 can power motors down to about 5V. (I think.) So you might need something else. MOSFETs will often work, but you will need to guard against shoot-through. (Google it.)
Do not PM me for help. I will delete immediately.
CONNECT THE GROUNDS!

After Tuesday, even the calendar goes W T F

habanero

Wouldn't the receivers that came inside these toy helicopters have their own H-Bridge circuitry, and is there any way you could use them instead of putting together your own?

I'm actually in a similar dilemma as I recently found the receiver and motors from an abandoned toy R/C plane that apparently crashed and was destroyed, and they're all intact and working. I'd like to be able to use these parts to build a new project, but I'm trying to figure out the electronics--plus what kind of connectors they use, which are around half the size of the ones usually used with Arduinos. Do you have any idea what they are and where one can buy them to adapt them to Arduino-sized connectors?

Isaac96

Well, about the connectors, I don't think I am a psychic. So please post pictures of them, preferably next to a ruler.
Do not PM me for help. I will delete immediately.
CONNECT THE GROUNDS!

After Tuesday, even the calendar goes W T F

habanero

Well, about the connectors, I don't think I am a psychic. So please post pictures of them, preferably next to a ruler.
Hey, no need to get snippy, these are standard connectors in the mini/micro r/c world and you either know what they are or you don't, and if you don't, you don't have to respond. I was specifically asking people who know about such connectors.

Isaac96

Sorry, I shouldn't have worded it that way. See your thread. 
Anyway, the helicopter receiver is probably SMD and hard to reverse-engineer. But post some pics and I will try to help.
Do not PM me for help. I will delete immediately.
CONNECT THE GROUNDS!

After Tuesday, even the calendar goes W T F

habanero

Sorry, I shouldn't have worded it that way. See your thread.
Anyway, the helicopter receiver is probably SMD and hard to reverse-engineer. But post some pics and I will try to help.
The question about a copter was posted by someone else. I got the motor from a crashed plane. As for the receiver, aren't these fairly standard so that data sheets could be found without having to RE them, or do manufacturers tend to keep that sort of thing confidential?

123Splat

Pepper,  So why are you hijacking this one when you got answers on your own thread.

Erich,  You don't need H-bridges on a helli, just drivers for the motors.  if they were large motors, with large draws, you might have needed Electronic Speed Controllers, but for small motors used in those mini-hellis, you can probably get by with just MOSFET's driven by PWM.

Isaac96

And do not use all p-type or n-type MOSFETS. MOSFETs also tend to need significant current on the base for the first few nanoseconds to prevent shoot-through. Use a MOSFET driver.
Do not PM me for help. I will delete immediately.
CONNECT THE GROUNDS!

After Tuesday, even the calendar goes W T F

habanero

#12
Jun 23, 2015, 04:33 pm Last Edit: Jun 23, 2015, 04:38 pm by habanero
Pepper,  So why are you hijacking this one when you got answers on your own thread.
If you re-read my initial post you'll see that the first part directly addressed the poster's question about an H-bridge, and the second part continued along the theme of re-purposing salvaged r/c parts, specifically a brushed motor and the wires coming out of it, which the poster also discussed, and how to drive it, which you can't do unless you know how to physically connect it to a circuit.

So sorry, I don't think it was threadjacking, it was riffing. This forum is about device hacking, and I was discussing the same sort of devices to be hacked.

Isaac96

@erichbschulz, are there any part numbers on the receiver? On the chips?
Do not PM me for help. I will delete immediately.
CONNECT THE GROUNDS!

After Tuesday, even the calendar goes W T F

123Splat

#14
Jul 01, 2015, 06:36 pm Last Edit: Jul 01, 2015, 06:42 pm by 123Splat
Erich,

Bottom line is your motors are brushed.  Makes things much simpler.
if you want to run the motors in one direction only, you only need a driver ( like an N-MOSFET ).
if you want forward and reverse, you need an H-bridge for a driver.

as to how beefy a driver you need, depends upon the size (current draw) of he motor in question.
Since you say 'toy helicopters', it would seem reasonable to assume motors smaller than 350/390 model size.
A small fet or an l293 ic should more than handle it.  You just have to determine the stall current of the motor in question, and size the driver for that plus safety margin.
Good luck, be safe, and have fun with the kids.

If you decide to go with a small H-Bridge, check out http://library.solarbotics.net/circuits/driver_tilden.html

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