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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. |
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| I built a similar radio many years ago, using a mosfet opamp from RS, a TL 7611 I think. Feedback resistor was 100M ohm! So powerful on 1.5v, it didn't need external antenna! | ||
| TO ALL VISITORS this schematic may not work. This is a similar op amp radio try it http://www.youtube.com/watch?v=3Zzmi_Kno4w&feature=fvwrel | ||
| cn any1 plz tell the specificatn's of the loopstk antenna used in the circuit...n y is an crystal ear ph used here..??? | ||
| how it works....how it tune different frequencies...if i want 98.3Fm....how i can choose?....what about coil...& its value..?..can we use speaker instead ear phone...??? | ||
| It is best to use an LM386 OP AMP for this circuit to work but this circuit is very delicate. You get best reception at night. The 365 variable capacitor is very Important. I also used a 220 uH inductor. | ||
| bull shit this dosn't work whats the value of the goddam coil in that shit ckt of yours. if you dont send me the value right away i assure you will get a nice spanking from me. (Editor's notes: Approved because this comment is awesome.) |
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| Just built this set with great results. To decouple and increase the 'Q' just wrap a few turns of the aerial wire around the coil. Used an R.F choke instead of a coil for S.W listening. In reply to KDB5IH, ebay is my usual source for variables. | ||
| Hi! I've heen a ham since 1997. But, I have been in electronics almost 50 years (back in the tube days)! 10-365pf variable caps are getting really harder to find.. Any suggestions?? 73 KD5BIH | ||
| i ve tried this ckt but failed to get the output..can anythin be used to modify d ckt n get a better output? also give some information abuot how to tune the ckt. | ||
| ve tried this ckt but failed to get the output..der is sum sort of disturbance obtained in d end..can anythin be used to modify d ckt n get a better result? | ||
| okay pls help me out how shuld i make it ?? i tried connecting all d components even used a circular kinda antenna and headphones as output but still its not working n also tell me exactly which tuning capacitor to use i got a 500pf one wid 3 terminals n used inductor wounding it for 30 rounds still not able to get it plsss plllss i need helf need to make it asap! | ||
| Are you supposed to connect Vcc to the Vcc pin on the op-amp? Otherwise, where? | ||
| My model of OP-AMP radio is catching a lot of noise. How can I boost the signal to noise ratio? I think the problem lies in impedance mismatching with the antenna. Is it so? | ||
| simple circuit but what about the output its working or not ? | ||
| 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. | ||
| what is a loopstick anteena | ||
| can u tell me about the loop stick antenna ana L1 in the figure | ||
| 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.) |
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| 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. | ||
| 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 | ||
| PLEEEEEEZ SOMEBODY TELL ME ABOUT ANTENNA. IS IT PIECE OF WIRE OR SOME SORT OF INDUCTOR? PLEEEEEEEEEZ GIVE DESCRIPTION. THANKS IN ADVANCE. | ||
| 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 | ||
| 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... | ||
| 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. | ||
| I couldn't find fm in description. Short wave is not always fm. I've built the circuit. Works well. You can replace the germanium diode with 1n914 or other germanium diode as well. It's demodulate the signal. The 741 is an audio amplifier. C2 used for DC decoupling. | ||
| whats the funtion of in34 diode and its equivalent i tried 2 get one bt cannot find one | ||
| we tried it. the op amp is working but no radio signal could be received. we tried it here in the Philippines.. what's wrong with it? | ||
| can we make this without using crystal amplifier??? and use normal earphones?? | ||
| I made this in 2 hours and combined it with a LM386 audio amp IC. WOW WORKS GREAT!!! If you don't have a ferite loop stick you could wind about 120 turns of 22ga wire on 2.5 inch form about 6 inches long. This is basicly a souped up crystal set ... | ||
| tried, op-amp is working, which could provide adequate sound output, but the receiver part is not working, no radio station can be found, i use loopstick antenna with a variable air capacitor, antenna length 18'' as suggested. what's wrong? (I'm in Hong Kong) | ||
| It is really wonderful to hear that we can make fm radio using IC 741 | ||
| by applying 324 opamp, can we build an extra output stage and use speaker? | ||
| 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... | ||
| can i change the 1N34 Germanium Diode what is her similar Diode if possile help me | ||
| If by using 741 ic we can make a fm radio that will be great. | ||
| what is mean by loopstick?.can i made this inductor as hane work? | ||
| Tried it, worked well for a wirenest, OP drove a pair of old morse training headphones paralel conected so there is a 2kohm load. I didn`t find a 10Mohm rezistor so I used a serial chain of trimers. For the LC I used the coil that`s described and a tuning capacitor that goes up to 380pF. I have the negative pole grounded and the antenna is a bit of a wire that goes across the room near the ceiling.Selectivity is really a bother as I heard morse from the shortwave and even commercial FM stations. But that must be because of the local transmition station placed a few km away. | ||
| can i use a LM324? if so could anyone give me a schematic?? | ||
| does this circuit really work. if so, how well? | ||
| HELLO,TO PICK UP SHORT WAVE CAN YOU EXPLANE FILM CAN PLUS IT SIZE.THANK YOU FROM JASON | ||
| what is the value of inductor? | ||
| give details about the crystal air phones | ||
| kwame,try 10-20 turns on 1inch pill-bottle | ||
| can anybody send me the exact ckt diag of a digital quality fm radio having surround sound output that is generally used in mobile fones (Editor's notes: Good luck with that...) |
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| i need to do this. some one tell me about the loop antenna. how many turn do i need. | ||
| I reccomend to keep terminals 10Mohm VERY SHORT. The best thing is welded directly onto 741, otherwise the gain drops significantly. The circuit in this case works well | ||
| I don't think it will work as good as you respect it!! It depends on an Operational Amplifier IC (LM741) & that kind of ICs doesn't have the ability to give a good result "sound" Similarly, we can't replace LM386 with LM358, because the first one is a sound amplifier while the other is same as 741 IC I recommed you trying to use LM386 instead of LM741, with changing the resistors, capacitors... etc | ||
| a 10-365pf varicap can be found in most cheap am radios experiment thats how to find things out the 10-40 try 5-30pf from internet electronic suppliehouses | ||
| 1n60's are available from scott lowe at his web site www.comtrolauto.com | ||
| i was told an 1n60 diode is better, radio shack can order 1n34a if you can get them off the cell phone kick and do something | ||
| does anyone have a simple police band-150mhz-160mhz circuit tuneable,saw one way back when need for all wave radio im building 9v+ please post one | ||
| i build a crystal radio using an op amp but it did not work: even you remove the op amp it just work the same when it has an op amp | ||
| what freqs is the loopstick for? am? | ||
| Your circuit didn't work here. Do you have a fm radio schematic that uses SC1088 IC?! please mail me!! thanks | ||
| OK! This is very interisting, Tjobela you raquire a multistage amplifier which I just so happen to be able to design. Contact me. | ||
| this is very good and small ckt of chip ic ,i will try it | ||
| your circuit had a great apperance when being used with an amplifier | ||
| poor circuits not good result | ||
| hi can i get some information about some simple receiver that has a bandwith between 80mhz to 110mhz | ||
| i couldnt find 1N34 Germanium Diode, is there any alternative? | ||
| Interesting, I wonder if everyone realizes that this is a original crystal radio that uses a germanium diode rather than a catwisker on a crystal. Those could drive a high impedance headphone but those are hard to find now. The op-amp helps drive a modern low impedance ear piece. | ||
| hi sir i need a audio amplifier circuit to drive an 8ohm speaker | ||
| I'm Thobela Nqodumo an electrical enginnering student at WSU university in East London i'm doing a final year,in project that i'm currently doing is the two channel simplex communication system so i would appreciate if u can help me in the audio amp part which will use op amps to drive a 8ohm loudspeaker.Thank u | ||
| I have done this circuit and i found it very usefull and i have listen to some channels thanks for giving this simple circuit | ||
| I had good luck with this little circuit, but, for me, the crystal earpiece was too shrill so I followed it with a Lm386 and use regular headphones. I never could get it to work well on the broadcast band so made coil with taps to cover from about 5.8 mhz to 10 mhz. Most international stations come in well--big problem is overloading and really poor selectivity which I don't know how to cure. | ||
| it is good,but ineed high rang FM reciver ,pls mail a 88-108MHz reciver, | ||
| this is a highly informative and easy circuit to get the desired frequency . i bless its designer. | ||
| please help me with a circuit diagram of a non inverting operational amplifier using a 12 v transformer as part of power supply | ||
| hello i need simple fm reciver diagram with explantion.to make in my home? thank you for your help | ||
| i dont think that there exists a 10-40pf cap letalone a 10-360pf cap! | ||
| he gave simple circuits thanks for giving | ||
| hi can u send me the circuit (used in cell phones) of a normal FM radio used mostly........?? | ||
| sir could u pls email me the circuitry of simplest fm reciever with detailed description of each components ... and could you pls tell how to make inductor from gauge wire ..i m a beginner , so pl bear. thanx | ||
| i have made dis cct n i found no eror in dis cct .. | ||
| Can you please comment on the comments.
I am saying answer every commentor next to his comment thnax (Editor's notes: You're kidding, right? If you have a question, use the forum.) |
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| hi ..i am technician please send me FM circuit with components details... | ||
| If you tap diode 2/3 of way up tunned circuit, loss in voltage is offset by rise in Q - better selectivity. Suggest you try an RF bypass C on diode output and use non-inverting op-amp input for possibly higher gain but certainly improved signal-noise ratio. Hope this helps. Found your page well worth a look and have saved many items. Frequency counter/probe VERY interesting. Have you tried HC counters for more speed? | ||
| hi,sir i need a simple cicuit of fm radio,plz send me on my email add.i will b thankfull 2 u | ||
| is there anymore information about this circuit in detail if there is please email me with information. | ||
| hi, i need simple airband reciever cicuits if u have plz send me thanks | ||
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