to TRF RADIOS Part 1
ANDREI LAZARESCU'S RADIO PROJECTS
My name is Andrei, I was born in Romania in 1987 and one of my hobbies
is electronics. In the following lines I will present to you a simple
The radio consists of two sections: R.F. and A.F. I combined the R.F.
section with adjustable selectivity from this reference:
and also from here: http://braincambre500.freeservers.com/MK484%20Receiver.htm
The A.F. section is from here: http://www.radiomuseum.org/forum/mk484_und_detektor_empfaenger_basteln_mit_mk484.html
and here: http://radiosammlung.homepage.t-online.de/seite8.html
The result? A performance receiver, sensitive (and selective, if it is
adjusted or at night), with a high quality of sound.
I used a small Medium Wave antenna from a walkman with digital radio
and a variable capacitor (VC) with two sections connected in parallel
from an old russian radio (2x280pF).
I read on the Internet that if you live in an area with strong signals
and you want to achive good performance and quality with this 3 pin IC
(MK484,ZN414 etc) you have to:
A) use a small or smaller ferrite rod;
B) use a variable supply to adjust the IC voltage (0-1,4V);
C) use two coils for the ferrite rod: main coil - L1 (for tunning) and
second coil - L2 (inductive).
You can try A, B or C, each of them improving the performance of the
receiver. But, if you use all of them (A+B+C) your receiver will work
The HP Jack allows you to connect a headphones and switch between
internal speaker and headphones.
The DC 9V Jack allows you to connect an external power supply of 9V to
the receiver and switch between internal 9Vbattery and external power
In the left side of diagram are equivalents (found by me from different
webpages and noticed all on a notebook) of the RF circuit.
In the right side of diagram I present a good, simple stabilised source
Here is an audio clip recorded from the completed radio: Click to Listen to the Audio
To More Electronic Projects
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