electronic speed control help needed

[hedgerow pete]

Managed to get hold of a kids electric scooter , the idea is to rip it apart to use the motor and speed controler systems to power a model boat i am playing with

now every thing is simple enough even for me the worlds greatest ***** with a soldering iron, where it went wrong was when i dismantled the hand grip twist speed controller, i was expecting some of tracked resistance design in stead i was meet with two magnets and what looks like a transistor of some sort,

so what i was thinking was to stick a charged up battery onto it and then use a standard resistance pot , i happen to have one of 470K and 47K and 100K avalible from the shed could i use this instead.

i was working only out of the maplin cat or the internet so parts can come from many places, the actual device its self would hace to produce some form of signal to send to the power controller so i was thinking resistance or may be some form of hall effect device, any suggestions people??

 

[roche]

That's possibly a hall effect sensor, to sense the throttle position. The actual speed control will be somewhere closer to the motor.
Without looking at the circuit, it is impossible to tell if a pot can be used instead...
There may be some mark on the transistor thingy - what do they say?

 

[RoofTops]

Roche is spot on I think. The wiring diagram in this link is not much help but I think the article describes what the little square thing is. http://www.simplemotor.com/hemotor.htm

Do you actually want a speed controller for your boat? If not then it might be better to start from the motor end and see how that is wired and set it up that way.

If you want a "throttle" the sort of speed controller used in model R/C cars might be a better bet. They can dissipate the heat generated. A small potentiometer of the sort found in old radios will just burn out I fear.

 

[itma]

So, using the whole electric/electronic package as a black box - you just need a mechanism for bringing a magnet nearer or farther from that hall effect sensor to adjust the motor speed?

 

[roche]

The hall effect sensor (if it is one) will be putting out either pulses or a variable voltage, which may be used to control a PWM speed controller. If it is a variable voltage, then it might be possible to replace the sensor with a potentiometer...

A potentiometer between the battery and the motor will die. (let out all the magic black smoke) The motor looks to be about 100W - quite a lot of current off a 12V battery.

 

[itma]

So, using the whole electric/electronic package as a black box - you just need a mechanism for bringing a magnet nearer or farther from that hall effect sensor to adjust the motor speed?

/ after replacing (like for like) the hall effect sensor with one that hasn't lost any legs ...


I was thinking that a magnet mounted on a bolt with locknut (screw it closer or further, simple?) or on a radio controlled proportional actuator (more expensive, but whole new boat game), would allow the entire existing system to be used without having to understand how it worked.

 

[Nose Ma]

In case you missed it Helix (who made your split plastic ruler) has significant financial troubles, so please help them out and buy a new one! It's a British institution.

 

[hedgerow pete]

your right the one i have is missing a leg thats why i suggested a pot instead, so where does one get hold of a hall effect transistor from and what sizes do they come in.

the actual control its self is a sealed unit with a series of pugs into it, apart from that i know nothing about it,

so make a devise to move magnets is easy considering what i am building so thats not a problem.

the suggestion of getting hold of a proper shop brought motor speed controler is also a very easy option, its ust expensive one as i have a 120watt 24volt motor here so we are dealing with unusual power requirements, most model boats are either 12 volt or less.

the only reason why i am trying to use this is because its free, a motor and speed controler for free is going to save me a couple of hundred quid,

the first choice and the best one was a 12 volt dc motor, so i was walking to the scrap yard to get hold of a windscreen wiper motor, or a car fan motor, to strip out of its housing , when i found this instead.

 

[itma]

your right the one i have is missing a leg thats why i suggested a pot instead, so where does one get hold of a hall effect transistor from and what sizes do they come in.
...

The tricky thing may be to ID the one you have (so you can replace it exactly or compatibly). Hopefully it has got some markings on it, a logo can give the maker, then the letters and numbers can be searched for. A magnifier might be helpful to see the markings clearly.
Actually sourcing the device *should* be relatively easy, once its identified.
Nasty companies deliberately remove chip markings ...

 

[will]

your right the one i have is missing a leg thats why i suggested a pot instead, so where does one get hold of a hall effect transistor from and what sizes do they come in.

the actual control its self is a sealed unit with a series of pugs into it, apart from that i know nothing about it,

so make a devise to move magnets is easy considering what i am building so thats not a problem.

the suggestion of getting hold of a proper shop brought motor speed controler is also a very easy option, its ust expensive one as i have a 120watt 24volt motor here so we are dealing with unusual power requirements, most model boats are either 12 volt or less.

the only reason why i am trying to use this is because its free, a motor and speed controler for free is going to save me a couple of hundred quid,

the first choice and the best one was a 12 volt dc motor, so i was walking to the scrap yard to get hold of a windscreen wiper motor, or a car fan motor, to strip out of its housing , when i found this instead.

what you have to think about, is the boat going have a rudder if it is then you will have to have a servo and radio to make it work

 

[hedgerow pete]

the boat is going to have a rudder and electric motor and several other things, i was going to buy a 2.2gig handset which will come with its own 6 channel reciever,

into the reciever i just plug the standard servo plugs into for the rudder extra and the speed controler which is normal a seperate unit takes its signal from the reciever. what i was trying to avoid and to be down right clever was to use the scooters motor and its speed controler system by very simple stuffing a servo into the scooters handle bars after i had chopped them up to fit, saving me a small fortune in a shop brough speed controler.

I was really was walking to the car scrap yard when i found the scooter and had a brain wave moment.

its just as easy to chuck the scooter away and carry on with the car windscreen or fan 12 volt dc motor and buy the shops speed controller if i dont sort out this hall effect device some time soon.

the think is and the reason why i asked here , is because i know some of our members have a massive grounding in electronics and like me love a challenge or the hedgerow stupid monthly question

next months question is allready being formed now as we speak,
so beware people how understand NMEA-0183 data output and gps units and depth sounders as i am coming for you