Simple VHF/FM receiver

Updated March 2010: http://jimbo.twilightparadox.com/easy_vhf_radio.jpg to find the schematic

Using one NPN transistor, one resistor, a handful of capacitors, and snippets of wire, you too can build this radio!
It can tune around the US FM broadcast band, the aircraft band, and the lower VHF TV channels (audio only, of course!).

It is basically a regenerative receiver, with a very weak audio output, hence the necessity of
amplification. The parasitic capacitance of the transistor apparently plays a large role here, though I do not understand it well. Care should taken towards the placement of the parts and lengths of the wires used, as this will change the tuned frequency!

Credit for the design is given to this video:
http://www.youtube.com/watch?v=E948kxaFdd8

Category:

Science & Technology

Tags:

• easy
• vhf
• fm
• radio
• electronics

[Mrnitrocker]

Sir, whts d value of the Inductor coils shown in the schematic??

[mrjimbopalmer]

@Mrnitrocker It really depends on the tuned frequency. It's just a bent piece of wire.

[ChiIdKiIIer]

hello i'm studying electrical engineering, this was my second week and i love it, i was just wondering if i'll get to know how to do this when i graduate?

[mrjimbopalmer]

@ChiIdKiIIer Well, if you only learn from classes, you should probably at least take some electives in RF. By the time you graduate you should have learned enough principles to understand these little circuits. You shouldn't be afraid to tinker with this stuff on your own or tinker after you finish lab assignments.

[ChiIdKiIIer]

@mrjimbopalmer you mean when i graduate after 4 years? oh man, i want to study tellecommunications ( sorry for grammar) so i don't know if that includes radios, receptors and all that stuff? or as an engineer i just design plans?

[mrjimbopalmer]

@ChiIdKiIIer You don't need to take university courses if you really want to make little radio circuits like this. If you have any spare time you can just start reading.

[nightghostyou]

thanks good stuff



[ChiIdKiIIer]

@mrjimbopalmer i know but i just wanted to know if i was able to do this after i'm done with college.

[mrjimbopalmer]

@velhart0000 It's hard for me to say what the problem could be. Perhaps you may try the circuit with different 2N3904 transistors. I did not have success with every transistor. Patience is key with this receiver.