AM Modulation Transmitter, Receiver

check out an outfit called Ramsey Kits. They used to have a number of small AM transmitter kits you could build.

In addition to the transmitter and receiver, you are going to need 4-8 different ways of modulating the carrier signal. A set of 8-555 oscillators (or 4-556's, or...) could produce 8 different tones, and a set of 8 active filters can be used to decode the tones. Make sure none of the tones are harmonics of other tones.

In re the signalling: Consider using a DTMF (touchtone) encoder and decoder. Not sure, but Ramsey might still make these kits. Short and sweet.

In setting up the modulation level, one could get it close by audibly listening to an AM receiver and setting the encoder output to somewhere below what could be discerned as distortion. On the decoder side, the decoder input adjustment could be accomplished by basic trial and error. Else take the final product to a two-way radio shop, make a friend and maybe they'll do it for free.

If you are in the USA, why not use broad cast band FM? If it is short range and low power part 15 service, audio tones and decoders can be used and any cheap FM receiver will provide the receiver. FM is more likely to stay tuned if you are not going to use crystal frequency control.

As others have said, http://www.ramseyelectronics.com/ is one source for inexpensive kits and ideas.

Have FUN!
TT3

Turbotroll3 commented about considering FM instead. I had thought about that, but the poster seemed to be adamant with AM, and where we should stick with that. But, in digesting the original for some hours, I really don't like the post question at all, in that it leaves open questions. Let's see if our inquirer can answer this and convince us: What is your application, other than what is not otherwise available over the counter R/C? Sorry guys, this is not on the level, I say. Quite often, see inquiries that are wane and with omitted specific detail and true application.. I sense a rat here. Seriously.

First of all a RAT? like come on. What does that even mean?

I have a boom truck which I use for lifting signs, light posts, electrical components while a guy works in a bucket truck at hights of above max 30 feet. I would like to be able to create a simple 8 control button in the bucket of the bucket truck to be able to control the boom truck operation .... following all safety concerns of course. The person in the bucket truck has a better view of the situation and allignment within fractions of an inch then the boom truck operator 40-50-60 feet away

That is all. I don't to run 50-6-70 feet of control cable which will get damaged during operation. Im sorry if i was blunt with my original question.

I played with a concept like that about 25 years ago to do control from remote radio broadcast sites back to the studio. It was frought with bugs because the tones got duplicated at times by other content on the signals. I was using sub-carrier insertion on the RPU units to do it. My point would be, depending ont the frequency you could run into problems with passing transmitters, such as CB, Police and other emergency vehicles as their signals could contain harmonics and spurious components that may trigger your control. That would be disasterous for the bucket operator if they were in the middle of a very intricate alignment job. Just a thought to throw the usual muck into the game that always raises its' ugly head in the form of Murphy's law.

Fred

AH - so human safety is definitely involved! That makes a huge difference! You definitely do NOT want AM. It is too prone to interference. I'm sure the people who insure your operations will have something to say about this, IF it is legal to do.

If you do try it, make sure that every channel has at least two signals (tones or whatever) required to activate that channel. That will greatly reduce the likelihood of spurious activation. Do NOT use the touchtone frequencies! You want to use something that is unique, so no one driving by or in the neighborhood can accidentally activate your system.

What he means is that anyone who would have a person ride in a bucket controlled by such a tenuous link would be worse than a rat. There are very good reasons that remote control equipment of this sort is so expensive and one of those reasons is the likelihood of the bucket occupant getting killed as a result of spurious operation due to failure or misadventure due to faulty a faulty control link. Getting sued is expensive!

I find rats to be cute. But okay. Thank you for the information on the benefits and consequences of the application. I think I am just going to end up designing a simple cable to be attaced between the two vechiles. Keeping it high will have it not get in the way of the guys.

I would like to create something along these lines thou. But just have a Remote control application be able to control 4-8 "output" at the reciever. I have the ability to create the circuits to have a small 5V circuit control high voltage/load applications.

At this point I just want to learn the process/theory/production of creating a AM or FM control which can control 4-8 outputs at the reciever. All inputs/otputs are just digital. So yeah...