Op Amp Radio

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Here is a simple radio that is easy to build and inexpensive. In fact, you probobly have all the parts you need in your junk box. You'll be suprised at the great reception with this little set.

Schematic

Parts

Part	Total Qty.	Description	Substitutions
C1	1	Tuning Capacitor
C2	1	0.1uf Disc Capacitor
R1	1	10 Meg 1/4 W Resistor
D1	1	1N34 Germanium Diode
U1	1	741 Or Similar Op Amp
L1	1	"Loopstick" Antenna
MISC	1	IC Socket, Crystal Earphone, Wire, Antenna

Notes

The antenna can be a piece of wire or a telescoping antenna. 18 inches is a good length for in the city.

The tuning capacitor is a regular broadcast band tuning capacitor. I got mine from a junked AM radio. I got the loopstick antenna from that same radio.

You can change L1 and C1 to recieve different bands (eg. Shortwave). To recieve shortwave, try this: Make L1 30 turns of 30 guage wire wound on a film can and make C1 a 10-365pf capacitor.

Combine this circuit and the 8 Watt Audio Amp for a really neat radio.

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Comments

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JEREMY Op Amp Radio Saturday, November 14, 2009 4:43:42 PM

You can use any coil or LC circuit that you might find for crystal radio designs on the web. LM386 amp works great with a small speaker. Can someone post coil spec's for SWL coverage.

kuldeep op amp radio Thursday, August 20, 2009 7:28:04 AM

what is a loopstick anteena

dhana Op Amp Radio Saturday, July 18, 2009 5:24:52 AM

can u tell me about the loop stick antenna ana L1 in the figure

keith Op Amp Radio Monday, March 09, 2009 7:43:04 PM

I'm only getting one station.. wonder whats hooked up wrong, or if this radio is only supposed to get one station. But i have it hooked up to a push pull transistor audio amp n speaker i had already built on breadboard for my psp and that one station comes thru loud and clear. And i have a 4 wire loopstick plus a 6 pronged tuning cap. one sides for am the other for fm. not sure how thats all supposed to go.
(Editor's notes: Place a 1K resistor in parallel with the detector.)

08ES 25 MUET,PAKISTAN Op Amp Radio Monday, March 09, 2009 2:56:48 PM

THE PURPOSE OF GERMANIUM DOIDE IS TO DEMODULATE THE SINGNAL OBTAINED FROM LC-TANK CIRCUIT, WHICH IS BEING CHARGED BY EMF INDUCED IN ANT BY SIGNALS. GERMANIUM DIODES ARE MORE SENSITVE BCZ THEIR BARIER IS LESS(0.3V) AS THAT OF SILICON(0.7V). OP-AMP SIMPLY AMPLIFIES DEMODULATED SIGNAL FROM DIODE.

anonymous Op Amp Radio Monday, February 09, 2009 6:31:07 AM

IN FIGURE THERE IS SYMBOL OF INDUCTOR & ANTENNA, BUT IN DESCRIPITION L1=LOOP STICK ANT:, SO WHATS VALUE OF INDUCTOR ITS VERY CRITICAL PLEASE SOMEBODY EXPLAIN IT, FROM T.LAMZON

anonymous Op Amp Radio Monday, February 09, 2009 6:25:43 AM

PLEEEEEEZ SOMEBODY TELL ME ABOUT ANTENNA. IS IT PIECE OF WIRE OR SOME SORT OF INDUCTOR? PLEEEEEEEEEZ GIVE DESCRIPTION. THANKS IN ADVANCE.

anonymous Op Amp Radio Thursday, January 15, 2009 12:39:31 PM

CAN I GET A PICTURE OF THE CIRCUIT W hich HAVE BEEN BUILT ALREADY AND ALSO THE TUNING CAPACITOR AS 6LEGS AN I WAS WONDERING WHICH LEG SHOULD I USE SINCE THE CIRCUIT REQUIRES 2 LEG PLEASE HELP ME OUT

anonymous Op Amp Radio Thursday, January 15, 2009 12:27:48 PM

what is the purpose of the 1n34 diode? can i use any diode or do i have to use that specific one? let me know...

texassignaltech Op Amp Radio Thursday, December 04, 2008 9:44:06 PM

The purpose of the 1N34 germanium diode is to detect and recover the transmitted audio frequency modulating signal, from the radio frequency carrier signal. Try to find a 1N60 germanium diode which should perform equally as well as the 1N34. What is important here is that you use a germanium type diode as opposed to a silicon diode. The germanium diodes have greater sensitivity to lower levels of rf energy.

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JEREMY	Op Amp Radio	Saturday, November 14, 2009 4:43:42 PM
You can use any coil or LC circuit that you might find for crystal radio designs on the web. LM386 amp works great with a small speaker. Can someone post coil spec's for SWL coverage.
kuldeep	op amp radio	Thursday, August 20, 2009 7:28:04 AM
what is a loopstick anteena
dhana	Op Amp Radio	Saturday, July 18, 2009 5:24:52 AM
can u tell me about the loop stick antenna ana L1 in the figure
keith	Op Amp Radio	Monday, March 09, 2009 7:43:04 PM
I'm only getting one station.. wonder whats hooked up wrong, or if this radio is only supposed to get one station. But i have it hooked up to a push pull transistor audio amp n speaker i had already built on breadboard for my psp and that one station comes thru loud and clear. And i have a 4 wire loopstick plus a 6 pronged tuning cap. one sides for am the other for fm. not sure how thats all supposed to go. (Editor's notes: Place a 1K resistor in parallel with the detector.)
08ES 25 MUET,PAKISTAN	Op Amp Radio	Monday, March 09, 2009 2:56:48 PM
THE PURPOSE OF GERMANIUM DOIDE IS TO DEMODULATE THE SINGNAL OBTAINED FROM LC-TANK CIRCUIT, WHICH IS BEING CHARGED BY EMF INDUCED IN ANT BY SIGNALS. GERMANIUM DIODES ARE MORE SENSITVE BCZ THEIR BARIER IS LESS(0.3V) AS THAT OF SILICON(0.7V). OP-AMP SIMPLY AMPLIFIES DEMODULATED SIGNAL FROM DIODE.
anonymous	Op Amp Radio	Monday, February 09, 2009 6:31:07 AM
IN FIGURE THERE IS SYMBOL OF INDUCTOR & ANTENNA, BUT IN DESCRIPITION L1=LOOP STICK ANT:, SO WHATS VALUE OF INDUCTOR ITS VERY CRITICAL PLEASE SOMEBODY EXPLAIN IT, FROM T.LAMZON
anonymous	Op Amp Radio	Monday, February 09, 2009 6:25:43 AM
PLEEEEEEZ SOMEBODY TELL ME ABOUT ANTENNA. IS IT PIECE OF WIRE OR SOME SORT OF INDUCTOR? PLEEEEEEEEEZ GIVE DESCRIPTION. THANKS IN ADVANCE.
anonymous	Op Amp Radio	Thursday, January 15, 2009 12:39:31 PM
CAN I GET A PICTURE OF THE CIRCUIT W hich HAVE BEEN BUILT ALREADY AND ALSO THE TUNING CAPACITOR AS 6LEGS AN I WAS WONDERING WHICH LEG SHOULD I USE SINCE THE CIRCUIT REQUIRES 2 LEG PLEASE HELP ME OUT
anonymous	Op Amp Radio	Thursday, January 15, 2009 12:27:48 PM
what is the purpose of the 1n34 diode? can i use any diode or do i have to use that specific one? let me know...
texassignaltech	Op Amp Radio	Thursday, December 04, 2008 9:44:06 PM
The purpose of the 1N34 germanium diode is to detect and recover the transmitted audio frequency modulating signal, from the radio frequency carrier signal. Try to find a 1N60 germanium diode which should perform equally as well as the 1N34. What is important here is that you use a germanium type diode as opposed to a silicon diode. The germanium diodes have greater sensitivity to lower levels of rf energy.