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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 MW radio.
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
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 very well!
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 for 9V.
Here is an audio clip recorded from the completed
to Listen to the Audio
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EVERYDAY AND PRACTICAL ELECTRONICS Website
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