RC Car project

[zodiaque]

Hey all, I'm new here and this is my first post, so If anything seems out of line, please bear with me

A project I am working on involves the conversion of an RC car from 6v to 9.6v.
I am pretty sure that passing the full 9.6v through the circuit board may damage something ( correct me if I am wrong of course). To eliminate that problem i am installing a Micro Potentiometer befor the board to trim the voltage down to six. I am fairly confident that it will work for that purpose.
The problem comes in stepping the voltage back up to 9.6v for the rear motor (only) that powers the car backwards and fowards. The direction of this motor is changed by switching polarities.
I'm thinking of using a relay, which would be triggered by the 6v signal coming from the board, this would open a separate 9.6v circuit to the motor. The question is, how do I go about doing that, and also, will i need two relays since the polarity has to be changed to change the direction of the motor? Any advise would be most welcome.
Thanx

 

[Nigel Goodwin]

Hey all, I'm new here and this is my first post, so If anything seems out of line, please bear with me

A project I am working on involves the conversion of an RC car from 6v to 9.6v.
I am pretty sure that passing the full 9.6v through the circuit board may damage something ( correct me if I am wrong of course). To eliminate that problem i am installing a Micro Potentiometer befor the board to trim the voltage down to six. I am fairly confident that it will work for that purpose.
The problem comes in stepping the voltage back up to 9.6v for the rear motor (only) that powers the car backwards and fowards. The direction of this motor is changed by switching polarities.
I'm thinking of using a relay, which would be triggered by the 6v signal coming from the board, this would open a separate 9.6v circuit to the motor. The question is, how do I go about doing that, and also, will i need two relays since the polarity has to be changed to change the direction of the motor? Any advise would be most welcome.
Thanx

If this is a 'proper' RC car (as opposed to just a toy one), everything is already available to do it.

Originally you had two batteries on the cars, 6V for the radio and servos, and a much larger, higher voltage, one for the motor.

You could easily use that scheme!.

However, in more recent times it's become common to feed the electronics from the motor battery, to do this a small regulator is used, these are freely available in model shops.

 

[zodiaque]

Actually, it is a "toy" R.C. car
it's basically an experiment to see if it can be done, would also be a bit of a shocker to other people if and when it works as it would appear to be a regular stock toy rc going at some relatively rediculous speeds. It's been done befor by someone I know, their car was originally 9v though, so the .6v jump was not that much and the board handled it.
I had considered the double battery idea, but I realised I would still have the same problem trying to get the 9.6v battery to power the motor.

 

[Nigel Goodwin]

Actually, it is a "toy" R.C. car
it's basically an experiment to see if it can be done, would also be a bit of a shocker to other people if and when it works as it would appear to be a regular stock toy rc going at some relatively rediculous speeds. It's been done befor by someone I know, their car was originally 9v though, so the .6v jump was not that much and the board handled it.
I had considered the double battery idea, but I realised I would still have the same problem trying to get the 9.6v battery to power the motor.

In that case it all depends how the motor is driven, you will need to know the circuit that drives it.

 

[Tom_Braider]

Zod,

You could use a resister to step down the voltage to the circuit board, but as far as the motor goes, you've got a couple of choices.

1. You could simply rely on the speed control not to deliver full power other than a jolt.

2. You could also insert a PWM (pulse width modulator) to chock down the motor.

However, what you're doing is stepping up the voltage by 150% and then reducing it again. If you want a slight goose without the headaches, why not use a 7.2v battery pack and avoid the mess?