The Little Duck has been given a second hand remote control car, which he is happy to play with as a car by itself, but we wondered if we might be able to replace the missing controls. Is it possible to just buy any remote working on the same frequency, or does it need to be the same brand (seems to be a fairly anonymous Chinese brand)?
I know there are some R/Cers among our number, so any advice would be welcome.
I'm not an RC car enthusiast, but I have flown RC aeroplanes for about 20 years. AFAIK, there's little difference between RC for cars and RC for aeroplanes, other than that the aeroplanes may have more channels (all mine are 9 ch) and they work on different frequencies - by law.
A 27MHZ car transmitter should talk to any 27MHZ receiver - certainly the 35MHZ aircraft (i.e. helicopters and fixed wing) transmitters generally don't care which make of 35MHZ receiver they talk to - I use Futaba transmitters and a mixture of receivers. There is a difference in receivers (certainly for aircraft) in that some are Pulse Code Modulation (PCM) and some are PPM (Pulse Position Modulation). My Futaba transmitters are (digital) PCM, but they will talk to an analogue PPM receiver if set up properly.
Whatever you do, don't try to convert the car to 35 MHz - that's illegal. 27 Meg is for cars, and 35 Meg for aircraft.
If you don't know the make of the 27MHZ receiver in the car, take it along to a good model shop and they will almost certainly try it out with a 27MHZ tranny. Presumably the car won't have more than 3 or 4 channels (steering, throttle, brakes maybe?) so a tranny will cost very little. You could simply buy a cheap 27MHz tranny off EBay and try it - you might be lucky - but a good model shop may be better value in the end.
You may need crystals - within the 27 (and 35) meg band, there are individual channels - and the older kit uses a crystal to set the channel to be used between tranny and receiver. If you buy a transmitter you need to know what channel the car's transmitter is set to. Some RC kit actually sorts out its own channels (called multiplex) and does not use a crystal. Again, the model shop will help you. I fly £1000 models that rely on a £5 crystal - seems crazy in this digital world, but it was state of the art only 10 to 15 years ago - all the RC display model pilots did it that way, flying model jets worth £20k. So, if you have a crystal receiver, you'll need to know what channel it's on.
The real cost is in the car batteries - if it's oldish, the batteries may be shot, as in they won't hold a charge. They can easily be replaced, but batteries are not cheap, and you usually need at least a couple so you can use one and have the second charging. That then means that you need a charger capable of fast charging - these tend to be fairly sophisticated and have software that maximises battery charge and life. It can all get a bit expensive (which is why I didn't go down the environmentally-sensitive path a few years ago and convert to electric - I fly good old nitro!). If you have LiPo (Lithium polymer) batteries in the car, you need to be very careful how these are charged - they are safe, but can be dangerous if mis-charged. If it's a cheapish car the batteries will probably be NiCad or NiMH - and these are very safe. The model shop will help you there.
But, if you can get to a good RC model shop I'd be surprised if you can't get it all working at not very much cost. It then depends on how much you want to spend! But be careful, RC gets addictive - well aeroplanes certainly do......