Electrical Engineering

[KFC]

How Would I Build A Digital Antenna Receiver/Transmitter For My Robot Like I/O Switches. This Might Be A Little Simple But I'm Not Good With Antenna, Receivers, And Transmitters.

 

Thanks,

[YT2095]

the most simple way would be to use a TDA7000 and a DTMF decoder chip, then for the transmit make a simple "Bug" type FM transmiter and use a DTMF Coder chip to feed it the audio signal.

this site has a little data on the 7000: http://braincambre500.freeservers.com/acameo.htm

 

Piece of cake

 

edit: this is the de/coder circuit(s): http://www.boondog.com/tutorials/dtmf/dtmf.htm

 

equaly simple!

 

and finaly the transmiter : http://www.electronics-lab.com/projects/rf/002/index.html

note you`ll only need to build the part to the Right of the 4.7uf capacitor in the middle.

 

start to finish will probably take you an afternoon

[KFC]

Those Are Analog Not Digital(I/O). If You Have Lets Say A 6 in. Wire Wrapped Around A 1/4 in. To Make A Coil On The Encoder/Decode Input/Output Do They Have To Be The Same On The Size Coil In The Transmitter/Reseiver.

[BhavinB]

There are digital transmitters and receivers you can buy. Coupled with a digital microcontroller like the PIC series from Microchip, you can make a pretty versatily I/O system. Just google it and you'll find what you need.

[YT2095]

the front end of Any radio and the back end of any transmiter is ALWAYS analog, you can`t escape that.

and DTMF(de)coder chips are designed to be interfacable with digital ICs.

 

and as for the "Coils" what are on about? do you mean the LC resonator coil for the radio frequency?

[KFC]

I Meant Do I Have To Make The Coil The Same Sized On Each Side Of The Radio Control. If Not Is There Some Equation To Figure Out What Size Variation I Need?

[YT2095]

the LC resonance will need to be the same frequency in both Rx and Tx units, yes.

it`s also a good idea to have the antenna tuned to the same frequency also, a 1/4 wave would be ideal for range and portability.

it`s roughly (300/Freq in MHz)/4 and that`ll give you your answer in metres.

at mw powers you`ll not have to worry too much about SWR.

[KFC]

the LC resonance will need to be the same frequency in both Rx and Tx units' date=' yes.

it`s also a good idea to have the antenna tuned to the same frequency also, a 1/4 wave would be ideal for range and portability.

it`s roughly (300/Freq in MHz)/4 and that`ll give you your answer in metres.

at mw powers you`ll not have to worry too much about SWR.[/quote']

 

 

How Do You Tune The Antenna? Isn't Just Coil Of Metal Or Is There A Variable Resistor Component Or Something.

[YT2095]

you can use a fixed capacitance and then alter the coil dimensions (some have threaded ferrite cores too) OR you can use a variable capacitor and a fixed coil. these two are wired in parallel to create a resonator.

for the antenna simply apply that calculation I gave you, and it`ll be fine.

[KFC]

Do I Use The Equation To Make The Coil Or Tune The Antenna?

[YT2095]

yes, take a look here: http://www.phys.unsw.edu.au/~jw/LCresonance.html

[KFC]

I Have Tons Of 12 Gauge Wire, What Do You Think The Best Size Wined For The Coil Would Be And What Transistor Do You Think Would Be The Best For This Coil?

[YT2095]

well for low power (it`s legal that way) I always use the 2n2222, they work all the way up to 200Mhz no problem.

as for the coil, you`ll find that 4 to 5 turns around a pencil will be great for the 80 --> 100Mhz mark, the less coils the higher the freq.

[KFC]

That Puts Things In Prospective. But Do I Need A Transistor Before A Decoder Chip?

[YT2095]

it doesn`t make any difference what order you get them in, you`ll need both anyway.

[KFC]

I Have A PIC 16F84 Do I Have To Hook A MHz Crystal Or Does have A Timer Already In Side It?

[KFC]

Can You Think Of A Basic 1 On/Off Switch Remote Control Schematic, Using 2n2222 Transistor And 12 Gauge Wire?

[KFC #2]

Is There Some Way I Can Use This But Make Into A Radio Control.

[YT2095]

yes quite easily.

[KFC #2]

To Change The Emitter Just Change The In-fared Diode With An Inductor Coil Or Is It More Complicated Then That?

[Tsunami]

Is KFC And KFC #2 The Same People?

[KFC]

Does anyone know a video encoder and video decoder that would work with these products Color LCD and Color Camera, Also how do you hook those up with the schematics that YT2095 gave me?

[KFC]

And how do you make the transmitter transmit more than twenty feet something more like 2000 feet?

[KFC]

Ok, Is there some way to boost the range at all?

[KFC]

If I change the Inferred Diode with this product: CHOKE,AXIAL,RF could I make it in to a radio controller?

 

How would I change the Inferred Receiver with another CHOKE,AXIAL,RF and would I use a to transistor?

 

How would I Boost the signal a couple of hundred feet?

 

 

 

All schematics make by Paul Oh