# RF transmitter-receiver circuits (in Off-topic)

## forktoadMarch 19 2008 10:40 PM EDT

CB is full of intelligent guys so I thought I should search for an answer here. RF signals are known to transfer energy signals. This is how they power bar codes, right? So all I want to know is how do you design a simple RF transmitter-receiver circuit? I would be really thankful to people if they could give a detailed explanation about this topic instead of just forwarding links (no matter how hard I try the language in those web pages appear indecipherable to me). Altough all related knowledge is welcome....

## AdminNightStrikeMarch 19 2008 10:49 PM EDT

First, what do you mean by "energy signal"? RF *IS* energy.

As for designing the circuit... do you actually mean "design", or do you just want to build it? If you are just looking to build it, all you need is a circuit diagram, of which google will turn up hundreds. If you are trying to design one yourself, well.. I think you have a lot to learn first about theory.

## QBsutekh137March 19 2008 11:02 PM EDT

Also, bar codes aren't powered, at least not most of them... Bar codes are passive -- they are read like words. The "eyes" reading the words -- well, those are more advanced (but pretty standard these days).

If the links people point you to are too advanced, maybe people aren't starting you out simply enough. You need to read about light, about optics. Get comfortable with that. Einstein didn't wake up with relativity in his head -- brother had some foundation first.

So, let's get basic -- do you like math? Do you like science? Do you like tinkering? If you want to see a radio receiver, take apart a \$1.50 transistor radio...won't help much, but you will see how basic it is. Antenna, modulation, heck, I think speakers themselves are amazing. Or maybe ears. Or both. Hell, it's all damn cool.

Where to you want to start? And yes, your answer should start at something simpler than a complete and instant comprehension of all things RF. *smile*

## forktoadMarch 19 2008 11:09 PM EDT

Let me rephrase the question:-
Can you give me the equation by which I can calculate the values of resistance and capacitance for the RF generator circuit?
Which oscillator is the best option for RF circuits?

See, the idea is to design or build a circuit which can transfer energy signals superimposed on RF signals (I had read in EFY that it was the best way to transfer wireless energy). I know one has to modulate-demodulate etc., already reading the theory part but I would love to get the basic idea about generating RF signals

## QBsutekh137March 19 2008 11:22 PM EDT

Heh, you went from me basically talking down to you to going way over my head. *smile* I'm not sure how to optimize the best options, etc... Do you have some modeling software that could help?

## iBananco[Blue Army]March 19 2008 11:45 PM EDT

"Can you give me the equation by which I can calculate the values of resistance and capacitance for the RF generator circuit?"

You want an LC, not an RC configuration, for starters.

## KhardinMarch 20 2008 2:20 AM EDT

I think Nightstrike had the right idea. Seems like a really open question. What frequency do you want to transmit? How far? I think the best bet is to find a schematic somewhere that fits your needs or even start studying schematics for awhile till you know how its usually done, then you can find out how to tweak the numbers.

I think a class would be the best bet though.

And as far as transferring wireless power ...

This article says it took the former physics guy four years to figure out a good way. So I imagine it's a pretty complex idea.

## forktoadMarch 20 2008 6:02 AM EDT

Thanks PrissyPeach. That started me off somewhere.

By the way Khardin, can you give me an alternate link to that page? I get the '404 not found' message everytime I click on the link. By the way what exactly did you mean when you said 'studying the schematics' anyway? (just couldn't understand that)

And Sutekh it was really nice of you to point out that I was not being specific enough. *smile*

;)

## AdminG BeeeMarch 20 2008 6:17 AM EDT

Khardin was pointing to http://money.cnn.com/magazines/business2/business2_archive/2007/04/01/8403349/ I believe.

## NSFYMarch 20 2008 9:18 AM EDT

You should look into RFID devices / sensors (not barcodes) - many are passive devices that rely on the energy of a transmitted RF signal to do something - usually just a reflection of the energy back to a receiver in an encoded format that contains some kind of information based on the spacing of some reflective interdigital transducers on the device.

## XenkoMarch 20 2008 10:20 AM EDT

I'm a chemist.

This thread hurts my brain.

## QBsutekh137March 20 2008 10:32 AM EDT

Xenko, maybe you can make a transducer based on organic molecules -- a living transmitter/receiver! *smile* I think that would certainly be impressive! *smile*