I need to control a brushed 540 motor (80 turn) with forward, reverse and brake control. I'll be using a 6-cell NiMH battery at a nominal 7.2V. I tried a proof-of-concept using the ubiquitous L298N motor driver (fwd / rev but no brake yet) and it worked perfectly except for losing 2v at the motor, which I understand is quite normal for the L298N. That's too much voltage drop for my application (a 1:14 scale Tamiya RC truck) and I don't want to have to increase the supply voltage if I can help it.
I know a basic RC car speed controller will handle the job perfectly but I want to be able to set up my own throttle / brake / reverse profiles and car speed controllers have their own special way of doing brake and reverse. I'm assuming it won't be possible (or easy) to reverse engineer a basic car speedo just to use its bridge (or whatever else it uses) unless someone has already done this and can point me in the right direction.
I can't find any specs for nominal / stall current on my 80T motor. I'm wondering if I might have to set one up on the workbench to measure it. I know low-turn RC motors can pull lots of current but these 80T motors tend to run all day on a 3000mAh battery. I wouldn't even like to guess at the current draw - in the RC car world, virtually everything is quoted in turns rather than amps so I don't even know the nominal and peak limits of my basic RC car speedos (of which I have more than a few).
Is there a motor driver or shield available which can handle the kind of current I need without affecting motor voltage? I'll need to be able to control motor speed in both directions and perform braking too.
Failing that, I guess I will have to build my own FET bridge - I'm not educated in electronics and it might be a steep learning curve, can anyone point me to a suitable schematic and can anyone advise what components I would need to handle the necessary current?
Please let me know if anything needs clarifying.
Any other hints / advice gratefully received