circuit

[hassan29]

i want a long range wakie-talkie circuit diagram, and its PCB lay out.if anybody have this plz send me

 

[audioguru]

Cheap walkie-talkies are made low power so they are legal and do not cause interference to other important radios (airplanes, police, fire department, ambulances etc). If you amplify their output then the amplifier will also amplify all their harmonics which will cause severe interference.

Buy a powerful FRS or GMRS pair of two-way radios instead. They are fairly inexpensive but their circuit is very complicated.

 

[Jackdaniel]

Those walkie-talkies used by police and army have long range, why is that guru?

 

[audioguru]

Those walkie-talkies used by police and army have long range, why is that guru?

They are properly designed so that they do not transmit harmonics and they have a powerful RF amplifier and a very sensitive receiver.

Three years ago I could buy two 2-way radios for only $40.00 and their range is 13km.
Today they are probably cheaper and have more range.

 

[Jackdaniel]

13km range with that little aerial??? Kinda hard to believe

 

[hassan29]

plz give me this

 

[hassan29]

i need long range wakie-talkie

 

[ronsimpson]

cell phone
They have about killed the wakie-talkie business. (CB and business band) and ham.

 

[audioguru]

13km range with that little aerial??? Kinda hard to believe

the length of the aerial is determined by the freq

 

[audioguru]

13km range with that little aerial??? Kinda hard to believe

The length of the aerial is determined by the radio frequency. Walkie Talkies for kids use 27MHz so their antennas are long.
FM radios use 100MHz so their antennas are about 80cm long. FRS and GMRS radios use 462MHz so their antennas are short.
My radio controlled airplanes use 2.4GHz (microwaves) so their antennas are only about 1.5" long.

 

[ronsimpson]

High frequencies (2.4ghz) is line of sight. If antenna 1 can not see antenna 2 it will not work. 2.4ghz will go through a wall but not a tree.
I have talked 1/2 way around the world (at very low frequencies) where power will follow the earth's curve.
Almost any hand held radio is high frequency and you are back to line of sight.

 

[Jackdaniel]

so are higher frequencies easy to recieve? Why is that guru?

 

[audioguru]

so are higher frequencies easy to recieve? Why is that guru?

Higher frequencies are not easier to receive.
Higher frequencies have a smaller wave length so they can use a shorter antenna.

Low radio frequencies bounce off the ionosphere so they can go very far around the world.
High radio frequencies do not bounce off the ionosphere, instead they go straight like light (their wave length and frequency are approaching the wave length and frequency of light) so they go only as far as you can see (the line of sight).

 

[carbonzit]

So since we're off on a tangent anyway (line-of-sight vs bounce transmission), is that why FM (88-108MHz) is line of sight, unlike broadcast AM (55-160KHz), because FM is higher frequency? or does it have something to do with the method of modulation? (I always thought the latter, but obviously have no formal schooling in this RF-type stuff.)

 

[Brevor]

So since we're off on a tangent anyway (line-of-sight vs bounce transmission), is that why FM (88-108MHz) is line of sight, unlike broadcast AM (55-160KHz), because FM is higher frequency? or does it have something to do with the method of modulation? (I always thought the latter, but obviously have no formal schooling in this RF-type stuff.)

It's totally dependant on the frequency, modulation has nothing to do with it.

 

[JimB]

broadcast AM (55-160KHz)

Should be 550 to 1600 khz.

JimB

 

[hassan29]

pls give me this diagran and pcb lay out soon

 

[Dragon Tamer]

pls give me this diagran and pcb lay out soon

The fact of the matter is that making your own radio transmitter is illegal without the government certifying it. We don't condone illegal activity on this site (usually) so if you want to break the law you will have to ask google for help.

 

[JimB]

The fact of the matter is that making your own radio transmitter is illegal without the government certifying it.

Not true in the UK, not true in the USA or most of the western world (if you have an approriate licence).

As we dont know where Hassan29 is located, this statement is irrelevant.

However, Hassan29 has not stated what frequency, what modulation type and what power he requires for his "high power walkie talkie", furher discussion is pointless.
I also suspect that he does not have suitable facilities to test that such a device is working correctly anyway.

JimB

 

[audioguru]

Where can you buy parts for making a custom radio today? He will need to buy a radio, take it apart then make it again.