Re: question for the electrical engineers
 

Hmm, hazarding a guess...

Looking at Maplins, 9V relays are quite hard to come by.

Maybe if you cannot use 12v then you will have to stick to 5v ones & stick 6 off 1A general purpose diodes (1N4002 etc) in the top +vline, the bit between junctions directly above the common pins of A2 & B1 relay contacts.
This would drop the relay control side to 5v while leaving 9v for the motor side.

The relays can then be like these or may have to be bigger depending upon the current drain of the motors in the R/C car.

The switches appear to be simple single pole "push to make" ones like these.

However, relays can use a lot of current, be quite big & expensive.
A circuit that uses transitors/FET's may be of better use.
This one that is from in the Cybot project ( currently in the loft) may be better. Adding switches or better still PIC control would be required.

Try seaching for robot control sites for further ideas.
here and here are other examples.

Re: question for the electrical engineers
 

they 9v thing is not particularly essential, its just for the test board as 9v square batteries are easier to come by than a 12v power supply ;)


i had a look at H-bridge drives, but my simple electrical nollidge gets a bit confused :)

remember, this is just a prototype that is gona be built on stripboard ;)

Re: question for the electrical engineers
 

The "stock" RC solution (to a simple reversing issue) would be to use a servo to tickle a couple of microswitches - not as fast as a full electronic solution.

I believe Maplin do RC kits

Re: question for the electrical engineers
 

well i have got 45cm of stripboard, several million components and my not so trusty JML coldheat, we will see what i can bodge together from this circuit ;)

it's not for a remote controlled car btw...