I am building "Slaughter of Lego" these days.. But I have a problem feeding the motors enough voltage. Without building a complicated H-bridge, and without burning Servos.
It is a dual core mothafukka, wait and see ;)
A little research shows that the H-bridge (L293D) that you use in the first robot tutorial can handle up 36V and an output current of 600mA (1.2A for up to 100usec). If that's not enough you can get other H-bridges. The L293B is pin-compatible, but you would need to put in the protection diodes yourself.
L293D datasheet: http://www.datasheetcatalog.com/datasheets_pdf/L/2/9/3/L293D.shtml
I just found out this:
There is a 1.5V voltage drop within the L293D driver chip - allways.
When using the 28 pin Picaxe board, motors and servos gets the same power-supply. Only motors gets 1.5V less. This means that if I would like the motors to have 6V, the servos will get 7.5, which is too litle for the motors and too much for the servos.
Damn! Best thing would be to hack into the board, and add a voltage-regulator before the servos, but it stinks!
Ok, I thought the problem was that the driver chip couldn't handle the current your motors were drawing.
There are some limitations to the Picaxe board. For example, you can either use the darlington chip or the resistors for the servos. You can't have both on the same board.
Hmmm.. thanks, worth taking a look at!