Looking for simple receiver radio suggestion

[Garyl]

Hey
Can you recommend me any simple nice receiver circuits?
It can be FM, AM, or anything else, i just want something interesting to make.
Preferrable reuse old parts from TV or junk...
Can you give me links to tested simple schematics of such circuits?
The more the better... thanks!

 

[Audioguru]

The words "simple receiver" means that the circuit will have very poor performance and sound awful.
It might be overloaded by strong local stations.
It might not be sensitive enough to receive weak distant stations.
It might have poor selectivity and receive more than one station at the same time.
It might be noisy and/or have extreme audio distortion.
It might eat batteries.

 

[ads-ee]

If they want simple maybe they should look at this thread on a LM386 based receiver. Probably has all the problems you mentioned ;-) (well maybe not all of them)

 

[Garyl]

not too simple...

I have a number of Ramsey and Vectronics 40 meter CW and SSB receivers which use an NE602 mixer with an LM386. My next project will be to convert one of them to the MW broadcast band using only the LM386.

Maybe one of them? I'd like to use 8ohm speaker with that.

http://www.radiomanual.info/schemi/RX/Ramsey_HR-40_user.pdf

Where can I get:
"4. Install L1(marked 421F-123), which tunes or preselects the signal
input from the antenna through C5 and R1"
? That part?

 

[BradtheRad]

The old-fashioned 'crystal' set might be doable. It requires few parts. It does not necessarily require a power supply. You might make (a) a variable capacitor and fixed coil, or (b) variable coil and fixed capacitor. The parts are not necessarily easy to fabricate.

An unpowered crystal set cannot drive a low impedance load. Therefore headphones should be high impedance, not low impedance. If you only have an 8 ohm speaker, then consider adding a 1-transistor amplifier stage to drive it.

 

[Audioguru]

How many AM radio stations will the single tuned LC pickup at the same time? A cheap AM radio has at least 5 LC tuned circuits to select only the station you want. Maybe the simple 40 meters radio has only a few Hams as stations so there is no interference from other Hams.

 

[c_mitra]

The old-fashioned 'crystal' set might be doable. It requires few parts. It does not necessarily require a power supply. You might make (a) a variable capacitor and fixed coil, or (b) variable coil and fixed capacitor. The parts are not necessarily easy to fabricate.

An unpowered crystal set cannot drive a low impedance load. Therefore headphones should be high impedance, not low impedance. If you only have an 8 ohm speaker, then consider adding a 1-transistor amplifier stage to drive it.

This is an excellent idea if you can get high impedance (more than 2K) headphones (they are not easy to find). You cannot use Si diode for the crystal (PbS is the ideal with a steel pin- basically a point contact diode rectifier). It will receive only the strong local station but a tuning capacitor can be used and you can perhaps listen to 2-3 local stations. It is really educative to start with...

 

[Garyl]

I'd prefer to look into something less simple than crystal radio. I can etch a PCB and buy few components....

Can I somehow hack old TV parts like tuner to receive radio or anything?

 

[c_mitra]

... something less simple than crystal radio...

I guess you mean more complex!!

TV tuners are electronic (most of the new TVs, that is) and they tune to VHF and UHF bands and they are not really useful for radio signals... (I really do not understand what goes on there...)

You need to make your own tuners; they are not black art. You can also use superhet mode and get good channel separation. Most of the time you will be using 455 kHz IF and you can listen to weak signals too.

 

[Garyl]

Is there any other way I can reuse TV parts? I have found only 7805, 7812 and the 2W / 5W audio amplifieres from TV useful so far....
I need some schematic that will be relatively easy to do with trough-hole PCB (I etch at home) and will work good enough without tuning...
I've tried "SUPER SIMPLE RADIO SCHEMATICS" in the past and I know that they are luck-based, I don't want now anything like that.

=================
http://www.radiomanual.info/schemi/RX/Ramsey_HR-40_user.pdf
Where can I get L1(marked 421F-123) for that Ramsey HR-40 project? Or how would I replace that?

 

[c_mitra]

That one is for a HAM radio and you WILL NOT be able to get common MW and SW radio transmission on that ...

L1 appears to be a simple transformer for the input coupling in the tuning stage. I really do not know where you get it but you can salvage one from any old radio...