fm receiver circuit. project with kids.

Thread Starter

Evanguy

Joined Dec 21, 2014
81
So me and my daughter made a pwm circuit using a 555chip and we dimmed a few leds and a little dc fan. she thought that was cool. we got talking and she wants to build a radio with me. i have found a few circuits online. im looking to make one without using ic's. and using more common components. i have about 4 circuits im thinking about using.

we plan to make an fm receiver then once that is working we want to make a transmiter to more or less make our own radio station lol.

So im wondering if any one has a circuit for a fm receiver that they know will work pretty well. i would hate to make this with her and have it not work lol. also i know not to use a breadboard and to solder the joints.

Ill post the links to the receivers i was thinking about using. i do hope they work with a speaker and not headphones.
 

Thread Starter

Evanguy

Joined Dec 21, 2014
81
Thanks. ill check my old parts radios for one. i was wantIng to do this with no ic's. just basic components and of course a variable cap i stole from an old 1977 realistic fm receiver
 

Thread Starter

Evanguy

Joined Dec 21, 2014
81
Ok thanks, i may have to reconsider the ic then. i do want it to work pretty well i just seen the oher link you added. thanks. il read that In a minute.
 

AnalogKid

Joined Aug 1, 2013
8,489
Sure you don't want to start with an AM receiver? It is conceptually and physically much more simple and less intimidating, far easier to understand at a basic level, and you can make the entire thing by hand - string a long wire antenna, wind the tuning coil on a paper towel roll, use a razor blade as the diode detector, and you get something that sounds exactly like what it is, a home-made radio. FM sounds like FM, but a crystal radio has a crackely radio-sounding sound, something I remember (and have been told many times by others) as a very emotionally gratifying experience.

Whatever you decide to do, there is a kit for it somewhere on the internet.

ak
 

Wendy

Joined Mar 24, 2008
22,146
That is how I cut my teeth on radio, AM. FM makes a really good next project.

With AM the detector is a diode, with FM the demodulator is much more complicated.

My first project was when I was about 10 years old, on a block of wood using wood screws.
 

AnalogKid

Joined Aug 1, 2013
8,489
Started with a strange little crystal radio kit from the local TV repair shop. No variable tuning cap, it had a coil with a slider. Dad ran an antenna cable from the upstairs bathroom to a large walnut tree in the back yard. After being sent to bed (9 years old) I'd sneak into the bathroom and listen to college basketball. To this day I still prefer it on radio over TV. Over the next few years I replaced the diode with a cat's whisker and wound aa larger, higher-Q coil. We moved to the end of a dead end street and I ran a much longer wire antenna to a tree in an undeveloped lot across the street (nothing illegal there, what could possibly go wrong). At night I regularly got New York stations and CKLW, and sometimes Seattle.

ak
 

Thread Starter

Evanguy

Joined Dec 21, 2014
81
^^thats really cool. i made a little kit one before but it never worked lol. also out my way we dont have am radio. my car wont pick anything up nore my in home receivers including sone expencive ones from the late seventies. so am is out. u less i also make a transmiter.
 

DickCappels

Joined Aug 21, 2008
6,459
All three projects noted in post #2 are regenerative detectors -essentially variations on the same theme. I experimented with a regenerative detector on FM about a decade ago and was surprised at how well it worked . I think any of the three circuits listed in post #2 should work fine -it won't be stereo and it won't be Hi-Fi but with a moderate signal you should work fine.

To start, get the easiest looking one to work with headphones then add audio amplification as needed.

 

Thread Starter

Evanguy

Joined Dec 21, 2014
81
Haha yeah thats always an option. some times depending on the weather we can get an old country station on am.

also i found a cd2003gp chip in my pile of parts so i now plan on using that ic to make a am/fm radio. ill also use the 2.3w 2cn amp ic that was on the same circuit board. as well as the ant and speakers, lol i mite as well just fixed that radio. but whats the fun in that.


Dickchappels, i thank you for your post. it was very much what i was looking for. a may not over complacate this and use your circuit idea.
 

Sensacell

Joined Jun 19, 2012
2,568
Yeah! the idea of starting with an amplified crystal radio seems like a good way to start.
It's not an epic slog to build, if the kids are enthusiastic about the process, you can move on from there and build a better one.

The worst is when you end up pushing the kiddies along and they just want Angry Birds.
 

Thread Starter

Evanguy

Joined Dec 21, 2014
81
thanks to every one who helped me in this thread, i ended up making http://3.bp.blogspot.com/-_etP0u4gSRE/Ul4mPwlBvJI/AAAAAAAAFgA/2guwEdAF9ao/s320/single+BF494+transistor+FM+radio+circuit.png that fm radio, it didnt work out we could only hear hissing no change in sound when turning the variable capacitor, so after a few hours of "tuning" we gave up on that, since then i found this pdf and ordered all the parts in the lists, i hope it goes better, it used the tda7000 for fm and tda2003 for an amp so i hope it goes a little better this time

http://www.transkommunikation.ch/dateien/schaltungen/diverse_schaltungen/radio_circuits/FM Receiver using TDA7000.pdf
 

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bertus

Joined Apr 5, 2008
20,568
Hello,

It is also possible to make a regenerative receiver.
There are many websites where you can find schematics:
superregenerative fm receiver

It can also be interesting to be listening to the shortwave, where you can receive a lot of foreign radio stations.
The attached PDF has some schematics to create receivers for the shortwave.

Bertus
 

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