Hi, can somebody help me, how to build fm mixer, thnx

Thread Starter

michael1978

Joined Jun 29, 2014
309
Hi,i build fm discriminator, somebody help me from here( i forget who was him), and also local oscillator 88-108Mhz, bandpass i know how to build and low pass filter, but just a mixer, how to build, can somebody explain me, thnx have a nice sleep, goodnight...
 

MisterBill2

Joined Jan 23, 2018
7,315
There are MANY websites that will have a circuit for all of those items available for free. What is described is all of the sections of an FM receiver. There are hundreds of those circuits easily available.
 

Thread Starter

michael1978

Joined Jun 29, 2014
309
There are MANY websites that will have a circuit for all of those items available for free. What is described is all of the sections of an FM receiver. There are hundreds of those circuits easily available.
Hi MisterBill, i search yesterday in google, but i dont find almost nothing, i dont undestand? how can be easily, they with write somebody example of tutor to explain, mixer :(
 

bertus

Joined Apr 5, 2008
20,883
Hello,

Have a look at the links of this page:
http://educypedia.karadimov.info/electronics/radiotuning.htm

I know that the page is somewhat old and some links will not work.
You can still retrieve a lot of the information using the internet archive:
https://archive.org/
Just paste the not working link in the wayback machine and see on wich date the link was still available.

An other source of good RF information can be found here:
https://www.radio-electronics.com/info/rf-technology-design/

Bertus
 

Thread Starter

michael1978

Joined Jun 29, 2014
309
Hello,

Have a look at the links of this page:
http://educypedia.karadimov.info/electronics/radiotuning.htm

I know that the page is somewhat old and some links will not work.
You can still retrieve a lot of the information using the internet archive:
https://archive.org/
Just paste the not working link in the wayback machine and see on wich date the link was still available.

An other source of good RF information can be found here:
https://www.radio-electronics.com/info/rf-technology-design/

Bertus
Hello Bertus, i try the first link i open i found some links of mixer tutorials, but still i dont know abot what they are talking)-;, second link i open and i search rf mixers, but he found nohing i dont know how o search, the third link, i open also yesterday i found this, mixer-bjt-01.gif
but i dont understand , the filter, do you see the output, and also the value of inductor and capacitor, is this correct mixer? thnx Bertus
 

bertus

Joined Apr 5, 2008
20,883
Hello,

The transistor is a non-linear element that can be used as mixer.
The S/C capacitor is used to suppress the higher frequencies.
The box shown in the collector of the transistor resambles the IF filter.
There you will find the IF filter to get the intermediate frequency.

Here is the complete picture with text:

BJT Transistor Mixer Multiplier Radio-Electronics Com.png

Bertus
 

Thread Starter

michael1978

Joined Jun 29, 2014
309
Hello,

The transistor is a non-linear element that can be used as mixer.
The S/C capacitor is used to suppress the higher frequencies.
The box shown in the collector of the transistor resambles the IF filter.
There you will find the IF filter to get the intermediate frequency.

Here is the complete picture with text:

View attachment 161092

Bertus
Hi Bertus, the second is easy one, i just need to find the transistor i dont know wich type and also capacitor value, duo you know maybe wich type of transistor i can use, and also do you know the value of capacitor ?

i wil like to ask you, is this also mixer? for fm
 

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Thread Starter

michael1978

Joined Jun 29, 2014
309
Then i would buy a ready made kit to assemble yourself , plenty on the internet .
Hi, i buy the kit fm108C, it was very good, but the problem is that i dont learn nothing about fm, what to buy else? when they dont explain formula how is working etc...…….do you know any kit with good explains?
 

Thread Starter

michael1978

Joined Jun 29, 2014
309
Hello,

The transistor is a non-linear element that can be used as mixer.
The S/C capacitor is used to suppress the higher frequencies.
The box shown in the collector of the transistor resambles the IF filter.
There you will find the IF filter to get the intermediate frequency.

Here is the complete picture with text:

View attachment 161092

Bertus
Hi Bertus i found this circuits
8425131483501753386.png
and the result

1160341483501787424.png

and i build in ltspice
here is my circuit, i dont get this result, why? what i make mistake?
 

Attachments

bertus

Joined Apr 5, 2008
20,883
Hello,

The two inputs shouls have different frequencies.
Can you show what the frequecies are?

It can also be that the BC548 has a to low Ft to work.
Better use a RF transistor.

Bertus
 

Thread Starter

michael1978

Joined Jun 29, 2014
309
Hello,

The two inputs shouls have different frequencies.
Can you show what the frequecies are?

It can also be that the BC548 has a to low Ft to work.
Better use a RF transistor.

Bertus
Hi Bertus, the RF is 1.1mhz, 200mV, and the LO is 1mhz and 2V, can you please tell me wich transistor to use i dont have BC548, because i reinstall windows 10, and i delete everything, can you tell of wich RF transistor to use because i dont know Bertus
 

bertus

Joined Apr 5, 2008
20,883

MisterBill2

Joined Jan 23, 2018
7,315
M1978, unfortunately google is almost the least effective search engine when looking for technical information. Thousands of hits wanting to sell whatever it is you are searching for, and they have no clue about what it is.
But some other search engines are more useful, fortunately.
"Schematicsforfree" and "the freeinformationsociety" websites have a lot of circuits, and even better they have a lot of links to other sites that have even more informative content, not just circuits. Sorry that my first response was not adequate.
AND, you have my sympathy for having windows ten. I tried it and found that it was unacceptable.
 

Thread Starter

michael1978

Joined Jun 29, 2014
309
Hello,

I assume you mean 1.1 MHz and 1 MHz.
The result will be 2.1 MHz and 0.1 MHz.
For those low frequencies, the BC548 might work.

There is a list of RF parts in the component selection guide of this forum:
Components Selection Guide
Have a look at post # 5.
Bertus i download libary of bjt from here and i found BC548B http://ltwiki.org/index.php?title=Standard.bjt, but does not work,

You might also be interested in the following book:
https://the-eye.eu/public/WorldTracker.org/Engineering/Electrical Engineering/Secrets of RF Circuit Design , Third Edition.pdf

Bertus
 

Thread Starter

michael1978

Joined Jun 29, 2014
309
M1978, unfortunately google is almost the least effective search engine when looking for technical information. Thousands of hits wanting to sell whatever it is you are searching for, and they have no clue about what it is.
But some other search engines are more useful, fortunately.
"Schematicsforfree" and "the freeinformationsociety" websites have a lot of circuits, and even better they have a lot of links to other sites that have even more informative content, not just circuits. Sorry that my first response was not adequate.
AND, you have my sympathy for having windows ten. I tried it and found that it was unacceptable.
Thank you for info, normal i use all time google to search for electronics and other things….but i gonna try yours link.
 

Thread Starter

michael1978

Joined Jun 29, 2014
309
Hello,

I assume you mean 1.1 MHz and 1 MHz.
The result will be 2.1 MHz and 0.1 MHz.
For those low frequencies, the BC548 might work.

There is a list of RF parts in the component selection guide of this forum:
Components Selection Guide
Have a look at post # 5.

You might also be interested in the following book:
https://the-eye.eu/public/WorldTracker.org/Engineering/Electrical Engineering/Secrets of RF Circuit Design , Third Edition.pdf

Bertus
HI its very good book, thnx i did not see...
 
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