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Simple RF FM receiver

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I have been working on trying to get a simple FM receiver to work for a while now and I haven't had much luck. If someone could do two things for me that would be great:

First; can someone show me a simple reciever that I could build (it has to actually work :)) so that I can do experiments on to see how I could make it better and what not (also add some types of add ons). It doesn't need to be a super high quality.

Second; can someone please explain what is needed to make a half decent RF receiver so that I can try to design my own.

Thanks! :D
 
You forgot to say which FM radio circuit you made so i am probably repeating something;
1) A very simple and cheap FM radio is a crystal radio. Look for it in Google. Its performance is terrible and it sounds bad.
2) A slightly more complicated FM radio is a super-regen circuit . Here is a project that is the original. The link to the recommended latest version does not work:
**broken link removed** . It has only a single Jfet as the "radio", is easily overloaded by strong local stations and picks up a lot of interference because its detector is AM not FM. It can play a few stations with distortion if you tune it to one side of a station's frequency.
3) Another poorly performing FM radio is an obsolete TDA7000 IC or a newer TDA7088 IC. The "radio" is available for only $1.00 at The Dollar Store. It "scans" for tuning but misses many stations. It is very distorted.
4) A pretty good older FM radio is a super-heterodyne circuit. A good one has a 3-gang tuning capacitor so that its input is tuned. A cheap super-heterodyne circuit does not tune its input so it is easily overloaded by strong local stations. Most parts are not available anymore so you might need to take parts from a radio.
5) A modern good quality FM radio has a frequency synthesizer with a quartz crystal oscillator and a phase-locked-loop. A TDA7513 IC is an example that is used in car radios. It has many variable parameters that need programming. It is in a tiny surface-mount package with 80 pins(!).
 
If you want to get an idea of what a really beefy man radio looks like on the insides, have a look at this link.
https://www.electro-tech-online.com/custompdfs/2010/06/cubicr3030.pdf
BTW, I worked for this company for six years. The radio sold for $20,000 but that included on-site service contract and it was for military use. It included AM, FM, USB, CW, and a few other features. Have a look at the detector module where the FM discriminator is. The block diagram should give you a few ideas on what to look for.
 
The problem is that this is just going to be a simple receiver that I attach to my go cart to receive a signal from an FM transmitter to make a simple 2 way radio. I don't want to make anything too complicated, all it needs to do is to receive a signal and turn it into an audio signal. I stumbled across YO3DAC - Homebrew RF Circuit Design Ideas . Are any of the receivers on there any good? Again, I'm not looking for anything complicated, I don't want to have to buy too many parts (any integrated circuits unless they're an audio amp).

I have made this one in a simulator and it worked pretty well.
**broken link removed**
 
A "simple" radio communications system has horrible or worse performance.
The frequency of the transmitter might wander all over the place. Then sometimes it works but other times it doesn't.
The transmitter might cause interference to a neighbour or to a police car's or aircraft communications. Then you are in big trouble.
The receiver might be overloaded by all the local stations unless you are in the middle of a huge desert. Maybe the receiver will have poor sensitivity (then no communications) or poor selectivity and mix many stations together with your transmitter. Maybe the distortion will be very high so that voices sound like buzzers.

Your attachment doesn't work.
 
As true as everything your say is, I still don't want to make something with a bunch of ICs that I don't have. I just want a really simple receiver that can be tuned to a specific frequency and I can hear someone on the transmitter. If it drifts a little that is fine, (unless it drifts my like 1.5MHz) If the voices sound fuzzy, that's also fine as long as I would be able to hear what they are saying.

From what I can tell, what I need to make a receiver is an oscillator, a mixer, and some way of tuning it, is that right?
 
From what I can tell, what I need to make a receiver is an oscillator, a mixer, and some way of tuning it, is that right?
Plus an RF amplifier with AGC, a high gain IF amplifier with transformers and crystal filters and an FM detector circuit. You also need an audio amplifier.
 
In my opinion, it'd be cheaper to just buy a wideband scanner. They can be bought on eBay as cheap as chips and often cover 25-1300Mhz with wfm, nfm and am modes. The sensitivity of a scanner will outperform any homebrew rx kit too.
 
A friend asked me why I wanted to make it so complex, he sugested that I just go out to the dollar store and buy a cheap pair of 27MHz or 49MHz walkie talkies and modify them. He has a point, the problem with that is the range of the very (very) cheap walkie talkies. They usually have a maximum range of 100 yards. The track is nearly a quarter of a mile across.

So now the question becomes; how can I modify the walkie talkie to boost the range of the signal? I tried once before to use an op-amp decoupled with a capacitor to boost random signals that it picked up. (that didn't work by the way) Google has been no help to me at all as usual. Please help me if you have any insight.

Thanks again; Vince
 
They have some very cheap walkie-talkies that will go farther than 100 yards. I got some for $50, and while their range is about 5 miles, I purchased them probably 5-6 years ago. So I'm sure you can purchase cheaper walkie-talkies with a suitable range?
 
FRS radios have a range of 0.5 miles to 2 miles. GMRS radios have a range of up to 10 miles.
They are inexpensive, costing about double or triple the cost of cheap toy walkie-talkies..
 

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That still leaves the problem of me having to take my hand off of the wheel to hit the talk button to send a message. The cheaper walkie-talkies send and receive simultaneously so I don't need to get too occupied with working the buttons.
 
Devise a circuit that will turn on the TX when you talk, I have that on one of my amateur radios. Make sure you don't have it too sensitive, otherwise it will turn on by another source such as the go-cart motor. You should probably put the microphone close to your mouth for the best performance.
 
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... The cheaper walkie-talkies send and receive simultaneously so I don't need to get too occupied with working the buttons.
Show a link to one that does! Only very complicated radio links (widely separated receive/transmit frequencies, large tuned cavities/duplexor) operate full duplex.
 
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That still leaves the problem of me having to take my hand off of the wheel to hit the talk button to send a message. The cheaper walkie-talkies send and receive simultaneously so I don't need to get too occupied with working the buttons.

Look out for some cheap pmr transceivers with a vox function(this means voice activated). This would enable you to chat without using a ptt button, and therefore allowing handsfree use. Regards. Damian.
 
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