My friend, who is interested in jet engines and welding is getting is working on a jet car, or something along that lines. I am just working on the electronics because I like the circuit building and like to understand how that works. I am wondering how controlling motors or relays or solenoids with a remote controller can work and how I would build this. I am thinking that maybe one frequency will control one output, and a slight frequency change will control another output. I may be totally wrong, but I want to control 3 or four outputs with radio control. I also want to be able to change the frequency from something like a couple different so if i have interference from like military or fm, i can change it. So maybe like 20 Mhz to 90 Mhz. (I know the FCC doesn't want me to broadcast at other frequencies being used and RC is only allowed 29 and 47 MHz, but I am not worried about the Law, and pretend I am doing this on Pluto, where I don't have to worry about the interference, and this is just a QA website, so don't mention the FCC)

So My question is how will I transmit a signal from a Radio Controller with a few pushbuttons and Have a radio Receiver pick up the signal and convert it to a signal a motor can read. I know that I will be using transistors to be amplifying the signal coming in, and I am trying to stay away from Ic's that you program with a computer because I like understanding how they work, like logic gates and transistors as amplifiers, not just CODE because I am not satisfied with programming something and not understanding how it works.

So Any information on Radio Control, how it works, and how to use the circuits will be great, because google hasn't helped me at all, and isn't even close to helping me understand the theory of radio control, or how to do this. I know without a MicroController the circuit will get complicated, but i will be willing to take the extra step to understand how it works.

I probably don't know what I am talking about and I am only 14, so sorry about making the question really horrible, and long, but any information will help.

  • \$\begingroup\$ I had a similar question a couple of months ago. This might help you get started, but you should know that it has thus far been pretty difficult to get into. electronics.stackexchange.com/questions/42923/… \$\endgroup\$ – Digital Brent Oct 30 '12 at 15:49
  • \$\begingroup\$ I've done this and trust me you don't want to do everything from scratch. The best strategy is to buy a commercial RC transmitter and receiver then decode the signal from the receiver with a microcontroller if you need to do anything non-standard. RC systems are cheap these days. A fairly good cheap Turnigy 9X cost around $60. All modern RC systems are good for up to at least 1.2km. Keep in mind that a fairly large 1m plane looks roughly 10 pixels in size (about the size of this letter 'I') at roughly 400m and starts disappearing from sight at that range. Glider pilots call it specking out. \$\endgroup\$ – slebetman Jun 20 '14 at 8:20
  • \$\begingroup\$ If you have done it, I would like to do it too. I believe making stuff from scratch will let me learn more, and not just do everything with code on a computer which is everything from hands on. I met someone who built a whole transceiver SSB 80-10 Meters out of scratch, literally he had NO IC's, just transistors, and other discrete components, and he was able to make the frequency drift minimal! \$\endgroup\$ – skyler Jun 20 '14 at 13:57

Nowadays, you don't just broadcast each signal on a different frequency. You send a digital stream that includes instructions for whatever you want to control. For example, a number proceeded by a 1 byte might control valve 1, a 2 byte valve 2, etc. You have to figure radio messages will occasionally get garbled or only partly received, so usually you send a packet of bytes followed by a checksum. The receiver ignores the whole packet if the checksum is not consitent with the rest of the packet. All this will include using a microcontroller in the transmitter and in the receiver. Once you have that, there are various chips that can do the digital RF communication between the two.

However, a much simpler way for you to just get things done is to use off the shelf hobby RC controllers and receivers. These take care of encoding the desired position of several "hobby servo" motors in the transmitter and decoding this in the receiver. You don't need to care how it is done. You move a joystick or lever in the transmitter, and a motor arm moves in the receiver accordingly. You can hook those up to whatever you want to control on the jet engine.

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  • 1
    \$\begingroup\$ I think there are few "DIY Modules" for RC systems. They can take in a PPM signal from a microcontroller, and a stock rc receiver can be used for the receiving end. (This is if you do not want to use a stock transmitter, but create something a bit different instead.) \$\endgroup\$ – varesa Oct 30 '12 at 17:00

There are basically three stages to this:

  • The analogue side of radio transmission and recieving: the basics of producing a signal at a particular frequency, and tuning into it.
  • Modulation: the basic types are AM and FM. When used to carry digital signals, these become ASK and FSK. Mobile phones and wifi have more complex modulation schemes to carry more data.
  • Coding: how the demodulated signal is turned into control outputs. This isn't really standardised, although some sort of pulse width modulation (PWM) will probably be the output.

Those are probably the things to start searching from. If you've not built a good old fashioned AM transistor radio, start with that. Then build a superhet FM radio.

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