Walkie talkie - Electronic Circuits Projects Diagrams Free

zachtheterrible · 7th June 2004, 05:46 AM

Quick questions:

What is the frequency that walkie talkies operate on? CB? and what frequency is that?

Do they use FM?

My friend has some regular walkie talkies that he got at circuit city or somethin' like that. They have what is called 'subchannels'. Are these just different frequencies, or are they encoded somehow?

Thanx :lol:

**Nigel Goodwin** · 7th June 2004, 05:57 AM

Quote:

Originally Posted by zachtheterrible

Quick questions:

What is the frequency that walkie talkies operate on? CB? and what frequency is that?

Do they use FM?

My friend has some regular walkie talkies that he got at circuit city or somethin' like that. They have what is called 'subchannels'. Are these just different frequencies, or are they encoded somehow?

Thanx :lol:

The original USA CB's were 27MHz AM, I've no idea what they use now?.

Certainly in the UK (and presumably elsewhere?) there are a lot of short range, licence free, walkie talkies on the market which don't operate on the CB band.

gerty · 7th June 2004, 06:01 AM

Depends on what you mean by 'walkie talkies'..Some are in the cb band about 27 mhz. Most of the newer ones are in what is called FRS, family radio service, 464. xxx mhz. I believe cb is am and frs is fm. I'm not sure what you mean by 'sub channels' all the frs radios I've seen are multiple channel with small steps (25 khz or so) in between frequencies. They also have what they call privacy settings which add a subaudible tone to the carrier, this is called pl (private line)codes. When this option is selected ,the radio will only hear another radio that is using the same tone.
It needs to hear the tone to open the squelch and pass audio.. A radio that doesn't have the option selected will be able to hear but not talk to one that has pl enabled.Hope I haven't confused you too much with my haphazard explanation 8)

andrew2022 · 7th June 2004, 04:31 PM

in the uk, PMR (portable mobile radio)freq is 446mhz fm (i think)

zachtheterrible · 7th June 2004, 04:38 PM

Sorry i forgot 2 mention where I live, usa, california. What I'm hoping to do is take a regular fm, or possibly am radio, and fiddle with it to get it to be able to hear walkie talkies.

andrew2022 · 7th June 2004, 06:51 PM

am assuming most people would use the licence free radios, so why dont you just buy a licence free radio? i remember when i was in florida a few years ago they were $15(14 channel) each ($30 for the 512 channel version)

Sebi · 7th June 2004, 08:18 PM

The Citizen Band middle range from 26,965 to 27,405Mhz, but with rotary switch available only 40 channels. The remained channels available only if the radio have "sub-channel" button. This button make a +10kHz shift. E.g.: CH16 have sub-channel, when the +10kHz shift activated, the PLL go to 16/a channel. CH20 haven't subch, so the shift go to 21CH.
Anyway some types (e.g. President) can work in AM,FM,USB and LSB modes

zachtheterrible · 8th June 2004, 05:10 AM

I'm actually doin' it just for the heck of it. I know that I could buy a regular walkie talkie, but . . .

What'll be cool about it too is that I'll be able to hear anything from the hightest frequency that the transistors in the radio can go all the way down to the bottom, just by putting in different capacitors (and possibly making a smaller inductor). Has anyone tried this?

I'm also hoping to make a circuit that would track where a certain signal is coming from. I know this sounds a little jamesbondish 8) , but u gotta admit that would be cool. Does anyone know the concept behind this kind of thing?

**Nigel Goodwin** · 8th June 2004, 05:58 AM

Quote:

Originally Posted by zachtheterrible

I'm also hoping to make a circuit that would track where a certain signal is coming from. I know this sounds a little jamesbondish 8) , but u gotta admit that would be cool. Does anyone know the concept behind this kind of thing?

It's called 'direction finding', you simply use a directional aerial to take a bearing on the direction the transmitter is. You then move to another place and take a second bearing - at least a second bearing, you may also take more!. You then draw the lines on a map, they should cross at roughly the location of the transmitter.

The 'James Bond' gear was unfortunately just fiction!.

Although nowadays, you can do it by having a GPS unit with the transmitter, sending it's location.

Dean Huster · 8th June 2004, 10:45 PM

There were also walkie talkies available (more like kiddie talkies since they were more toys than anything) on the 49MHz band shared with older cordless phones and baby monitors. If you're a ham (amateur radio operator), you can use walkie talkies that operate on the various ham bands, e.g., 2 meters.

Dean

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7th June 2004, 05:46 AM	(permalink)
zachtheterrible	Walkie talkie Quick questions: What is the frequency that walkie talkies operate on? CB? and what frequency is that? Do they use FM? My friend has some regular walkie talkies that he got at circuit city or somethin' like that. They have what is called 'subchannels'. Are these just different frequencies, or are they encoded somehow? Thanx :lol: __________________ I'm no electronics god, i just talk too much.

7th June 2004, 06:01 AM	(permalink)
gerty	Depends on what you mean by 'walkie talkies'..Some are in the cb band about 27 mhz. Most of the newer ones are in what is called FRS, family radio service, 464. xxx mhz. I believe cb is am and frs is fm. I'm not sure what you mean by 'sub channels' all the frs radios I've seen are multiple channel with small steps (25 khz or so) in between frequencies. They also have what they call privacy settings which add a subaudible tone to the carrier, this is called pl (private line)codes. When this option is selected ,the radio will only hear another radio that is using the same tone. It needs to hear the tone to open the squelch and pass audio.. A radio that doesn't have the option selected will be able to hear but not talk to one that has pl enabled.Hope I haven't confused you too much with my haphazard explanation 8) __________________ gerty

7th June 2004, 04:31 PM	(permalink)
andrew2022	in the uk, PMR (portable mobile radio)freq is 446mhz fm (i think)

7th June 2004, 04:38 PM	(permalink)
zachtheterrible	Sorry i forgot 2 mention where I live, usa, california. What I'm hoping to do is take a regular fm, or possibly am radio, and fiddle with it to get it to be able to hear walkie talkies. __________________ I'm no electronics god, i just talk too much.

7th June 2004, 06:51 PM	(permalink)
andrew2022	am assuming most people would use the licence free radios, so why dont you just buy a licence free radio? i remember when i was in florida a few years ago they were $15(14 channel) each ($30 for the 512 channel version)

7th June 2004, 08:18 PM	(permalink)
Sebi	The Citizen Band middle range from 26,965 to 27,405Mhz, but with rotary switch available only 40 channels. The remained channels available only if the radio have "sub-channel" button. This button make a +10kHz shift. E.g.: CH16 have sub-channel, when the +10kHz shift activated, the PLL go to 16/a channel. CH20 haven't subch, so the shift go to 21CH. Anyway some types (e.g. President) can work in AM,FM,USB and LSB modes

8th June 2004, 05:10 AM	(permalink)
zachtheterrible	I'm actually doin' it just for the heck of it. I know that I could buy a regular walkie talkie, but . . . What'll be cool about it too is that I'll be able to hear anything from the hightest frequency that the transistors in the radio can go all the way down to the bottom, just by putting in different capacitors (and possibly making a smaller inductor). Has anyone tried this? I'm also hoping to make a circuit that would track where a certain signal is coming from. I know this sounds a little jamesbondish 8) , but u gotta admit that would be cool. Does anyone know the concept behind this kind of thing? __________________ I'm no electronics god, i just talk too much.

8th June 2004, 10:45 PM	(permalink)
Dean Huster	There were also walkie talkies available (more like kiddie talkies since they were more toys than anything) on the 49MHz band shared with older cordless phones and baby monitors. If you're a ham (amateur radio operator), you can use walkie talkies that operate on the various ham bands, e.g., 2 meters. Dean __________________ Dean Huster, Electronics Curmudgeon Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines). R.I.P.