generator cct

[tim0611]

Newbie here looking for help with a circuit for a generator to charge the battery on a large remote control helicopter.
Basically I'm looking to mechanically drive a brushless motor (3 phase) from the output shaft of the engine, rectify this and use a voltage regulator to supply 5.6v to my battery pack.This would allow me to fly almost continually (dependant on the petrol tank level) without having to worry about voltage dropping in my electronics.
I am an electrician by trade have soldering and pcb manufacturing knowledge from my apprenticeship, just cant remember anything about cct design!! it was 20 years ago so really I need a boffin who could tell me what components to use and a connection diagram.Any advice greatly appreciated.

 

[Roff]

I don't know if I can help, but anyone who attempts to will need to know the output voltage and frequency (and current output capability, if you know it) of the generator.

 

[jrz126]

Also, the kind of batteries that you are using might be helpful, some of them require a special charging procedure.


oh and ummm....whats a boffin? :?

 

[williB]

a boffin is an Brittish term for expert..

 

[tim0611]

generator info

ok guys here goes :
output from generator is 6.5v ac
KV = 850 rpm/volt
Rm=0,169 ohms
IO=0.6A
Unregulated o/put =12v 10A
After regulator 5.4-5.6v
Batteries used will be Nicad 1400mah
rotational speed of generator approx 11000 rpm not sure if that equates directly to freq. for a brushless motor but should be around183.3 hertz if my maths is right!
motor being used is Himax2812-850
**broken link removed**

 

[tim0611]

oops sorry ignore 6.5 v o/put
I'm a bit thick :?

 

[williB]

Tim , i understand what you want to do..
Is this the motor that you wish to use ?
https://www.electro-tech-online.com/custompdfs/2005/09/Himax_HC2812-xxxx.pdf
So all you need is a way to rectify three phase ..Correct ??
If so just connect your three output wires to six diodes as shown..

 

[williB]

What exactly is the voltage of your battery pack..??

 

[tim0611]

Thanks for the replies so far
Yes that is the motor I'm planning to use
battery volt=5.4v
Ive seen a cct where there is a 2200 microfarad capacitor with the three lots of diodes in parallel with it but I'm not sure why-smoothing?.
The resultant dc o/p then needs regulating to 5.4v to charge the battery and I dont know how to regulate the voltage or the current never mind work out what components I need!
Can I use any diodes or do they have to be a specific type?Sorry for the questions but as i said its many years since I studied electronics and its a case of use it or lose it.

 

[williB]

Thanks for the replies so far
battery volt=5.4v
Ive seen a cct where there is a 2200 microfarad capacitor with the three lots of diodes in parallel with it but I'm not sure why-smoothing?.
The resultant dc o/p then needs regulating to 5.4v to charge the battery and I dont know how to regulate the voltage or the current never mind work out what components I need!
Can I use any diodes or do they have to be a specific type?Sorry for the questions but as i said its many years since I studied electronics and its a case of use it or lose it.

For one thing ,To actually charge your pack you will need more than 5.4V to push the current into the batteries..
From what i've seen of the generator you want to use , it has more than enough power ..
what is the power drain of the electronics ( of the copter) you are using??

 

[tim0611]

Typed in volt reg into browser and found some info,could I use an LM338 which can handle 5A or an equivalent type of thing?
if so how on earth do I connect it and what else would I need in the cct?

 

[williB]

Ive seen a cct where there is a 2200 microfarad capacitor with the three lots of diodes in parallel with it but I'm not sure why-smoothing?.

yes

Can I use any diodes or do they have to be a specific type?

Type 1N400X will work ..

 

[williB]

Top right of page 7 is a configuration that will work..
https://www.electro-tech-online.com/custompdfs/2005/09/LM138.pdf
Not that the regulator is really heavy , its not ,but how much weight can the circuit board be .. or dosnt it matter..?

 

[tim0611]

Heli will lift at least 10 pounds so weight shouldn't be a problem!
Such good and quick advice-this forum is a great source of info for a dummy like me.
So the pos connection from the rectifier goes to the Lm338 and do I just tie down the neg from the rectifier to earth/ground?
one last question-if i can get this to work is there an automatic way to stop outputting to the battery when its fully charged or will constantly outputting to the battery be ok?

 

[williB]

How much power does your circuitry draw.??

So the pos connection from the rectifier goes to the Lm338 and do I just tie down the neg from the rectifier to earth/ground?

yes the ground from the rectifier goes to the ground on the regulator and to the negetive of the battery pack..

 

[tim0611]

sorry i pm'd you with that never posted it!
all up the servo's, lights, retractable undercarriage,electric start and siren should pull no more than 5A

 

[williB]

if you have XP you may never see a PM , because of the built in pop up blocker

 

[tim0611]

ok thanks and sorry

 

[williB]

did you get my pm ?

 

[Roff]

What is the horsepower output of your engine?