ESC: the Electronic Speed Controller:
originally electric radio boats had a variable resistor, like what used to be in mechanical train set controllers, operated by a sweep arm these in the late 1980s gave way to smaller, lighter electronic units, which were back then quite expensive, though prices have tumbled, some even have a BEC on it, which means Battery Eliminating Circuit, what this means, your nice 4 cell battery pack you had with your radio, well you dont need it so put it on your shelf
These often have a mirriad of wires coming out of them, blue wire, yellow wire, red wire black wire and a 3 core ribbon, so what goes where?...
the 3core ribbon goes to the Reciever, where it takes its command signals from
the red and black wires go to the battery, this is where your esc takes its feed from, more often than not it has a tamiya plug on it.
The yellow and Blue wires go to the motor, and are the output from the esc, so dont what ever you do, connect the battery to these wires, otherwise you will let the smoke out of the esc, which putting it mildly isn't good, the smoke needs to stay inside the esc for it to work. (yes electronic items rely on the magic smoke)
Some of them may have a "set" button on them, please follow instructions of your esc as to how to set it up
one of the most common questions is: "If I have BEC on the esc, Do I still need the receiver pack?"
Answer: No, your esc provides power to the receiver but if you do want to use the esc and the battery pack, remove the red wire from the plug at the end of the ribbon and tape it back
another one that crops up is the use of multiple esc's that have BEC, such as the Mtroniks Viper range. This is again not a problem, just decide which one is the master esc, and then on the others, remove the red wire from the ribbon tab
There are also coming onto the market brushless esc's, these are for brushless motors and originally came over from the aircraft scene, many dont have reverse so keep them for fast racing boats or model hover craft where reverse is not needed.
many esc's have a rating on them, both for output and input, example: 4.8v-12v 15a 4.8v is the minimum voltage this esc needs, 12 is the maximum, and will work quite happily on ni-cad / ni-mh packs and lead-acid packs, the output voltage will be the same as the imput voltage, however the output will be able to stand up to 15 amps, this means that if your motor pulls more than 15a, you need the next esc up, as if you pull more than the 15a, you will let out the smoke, same if you put too much voltage through it, (like 14.4v (2x 7.2v packs in series).
Electronic items work if the smoke is kept inside and cease to function if the smoke is let out