Just happened to come across this!, although it's HF amateur band, the principle still holds - it's a complete transceiver using the same transistor for both transmit and receive!.
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audioguru said:Nigel,
I like the way that the circuit mutes the audio during transmitting by using the same diode used for AM detection.
audioguru said:MStechca,
Your "radio" manages to pickup the hundreds of thousands of watts of signal from CH-TV that is right next door?
:lol: :lol:
my receiver can pick up CTV (toronto), and CH (hamilton) TV stations
audioguru said:Where would the transceiver have a BFO connected to provide a tone during its receiving a blank carrier?
The only time I used crystals was with a voice scrambler that used a MC1496 balanced modulator/multiplier IC and the communication link was radio. When I tried it with a 2nd scrambler with the same crystal frequency then the beat note was only about 1Hz. The oscillators weren't tuned. It produced an interesting effect: if somebody was between and was picked-up by both mics then their voice level increased then decreased slowly like they were walking towards then away from the mics. :lol:JimB said:The crystal oscillator is also the BFO.
A problem with such a simple scheme is that if the the other guy nets spot on to your frequency, you wont hear him. He would have to be a bit off your frequency to get a beat note.
JimB said:audioguru said:Where would the transceiver have a BFO connected to provide a tone during its receiving a blank carrier?
The crystal oscillator is also the BFO.
A problem with such a simple scheme is that if the the other guy nets spot on to your frequency, you wont hear him. He would have to be a bit off your frequency to get a beat note.
An entertaining toy for a bit of fun and experimentation, but not a serious bit of kit. (A bit like a super-regen receiver really).
JimB said:Nigel
I am familair with all the concepts of QRP and direct conversion receivers.
My comments were directed at the circuit as shown.
There is no facility to pull the crystal, the selectivity in not defined by any particular filter, and the sensitivity will be fairly poor.
Yes it will work quite well within its limitations, but it does have limtations.
JimB said:
mstechca said:audioguru said:MStechca,
Your "radio" manages to pickup the hundreds of thousands of watts of signal from CH-TV that is right next door?
:lol: :lol:
Did you read what I said I can receive?
my receiver can pick up CTV (toronto), and CH (hamilton) TV stations
audioguru said:Dit, Dit, Dit, Daw, Daw Daw, Dit, Dit, Dit. Dit, Dit, Dit. Send Over Some Sandwiches! :lol:
Isn't the SOS ??Pommie said:audioguru said:Dit, Dit, Dit, Daw, Daw Daw, Dit, Dit, Dit. Dit, Dit, Dit. Send Over Some Sandwiches! :lol:
Has every one else realised that the little tune that is now associated with SMS messages is actually Morse for SMS - Dit, Dit, Dit, Daw Daw, Dit, Dit, Dit.
Mike.