301 Threads found on edaboard.com: Fm Circuit
The circuit has already a FM input DEV. It should work for FSK as well. The FM input suggests that the PLL bandwidth is low enough not to work against the modulation. You would preferably use a DC-free modulation scheme, either using Manchester encoding or some kind of "whitening".
RF, Microwave, Antennas and Optics :: 01-20-2017 22:32 :: FvM :: Replies: 4 :: Views: 501
Hi , Guys
I have UHF FM Transmitter with power about 5W
I want it to send video signal through AM the carrier frequency
here the important section of schematic :
I tried to inject signal in Q407 emitter ( i think this make low level AM ) after remove R408 the picture shows up in my TV with lot of noise and
RF, Microwave, Antennas and Optics :: 01-12-2017 12:27 :: battery14v :: Replies: 16 :: Views: 953
In most countries it is illegal to transmit and cause interference to broadcast stations (100MHz is in the middle of the FM broadcast band) and the harmonics of your simple circuit causing interference to aircraft, police and ambulance communications.
Elementary Electronic Questions :: 01-07-2017 15:19 :: Audioguru :: Replies: 15 :: Views: 765
The circuit is too simple and automatic gain control is missing so it will be overloaded by strong local stations. Even my cheap old Sony Walkman FM radio has a manual local-distant switch. Since I live in a huge city with many strong local stations then the switch is always in the "local" position which reduces its sensitivity then it cannot picku
Hobby Circuits and Small Projects Problems :: 08-23-2016 02:50 :: Audioguru :: Replies: 2 :: Views: 385
Hi there. I registered today and this is my first thread here. I see that you guys do the help all the time, so my guess is that I will get some help too.
I recently completed fm transmitter ( no tune RDVV ) and I have problem because it is losing lock when power is more than about 0,5 W approximately. Frequency counter says that when it lose l
RF, Microwave, Antennas and Optics :: 04-29-2016 14:20 :: Nermin :: Replies: 24 :: Views: 1998
If the BC547 input transistor has minimum hFE at 100 then for its collector voltage to be 1.5V and with a collector current of 1.5V/22k= 68uA then its base current must be 0.68uA. The voltage across the base bias resistor will be 1.5V - 0.58V= 0.92V then its value must be 0.92V/0.68uA= 1.35M.
If the BC547 has maximum hFE of 700 then the base bias
RF, Microwave, Antennas and Optics :: 03-19-2016 18:37 :: Audioguru :: Replies: 3 :: Views: 612
A 0.5-2GHz band oscillator is absolutely different than FM band oscillator and this circuit will never work at that band even the components are changed.
0.5-2GHz VCO ( I presume that the modulation will be FM ) is almost impossible. The classical VCOs cover approximately 1 octave not more.
This wideband VCO will have very high
RF, Microwave, Antennas and Optics :: 02-07-2016 11:36 :: BigBoss :: Replies: 10 :: Views: 683
I need add pre-emphasis circuit in FM system.If it is 6dB/Octave,and -54dBV this pre-emphasis curcuit output level at 300Hz,then how to caculate the output level at 3KHz?
Thank you in advance,
RF, Microwave, Antennas and Optics :: 01-27-2016 20:25 :: John_li :: Replies: 0 :: Views: 364
To appear the "capture effect" in FM, the stronger signal should be 3dB or greater than the weaker signal.
Anyway, this is the main reason why airplanes use AM instead FM.
While ago somebody told me that AM is used because was invented 30 years before FM, which in fact is not totally wrong.
RF, Microwave, Antennas and Optics :: 01-24-2016 20:55 :: vfone :: Replies: 11 :: Views: 674
I want to design a simple FM transmitter circuit, but also not compromise the spectral purity by using one of those all in one transmitter ICs. After hours of research, I've come to the conclusion that the ADF4360 is probably the best option for low component count and high spectral purity.
Anyway, the problem is that I have very little knowledg
RF, Microwave, Antennas and Optics :: 01-08-2016 05:13 :: Synaps3 :: Replies: 1 :: Views: 521
At the oscillating frequency Q2 is a common base amplifier. The feed back to get it oscillating is provided by C5. It may work with out C5 if the parasitic capacitance of the device is high enough.
R6 provides the base current for Q2 and R7 limits the collector/emitter current to the required value; inthis case it will be a little more than 8mA.
RF, Microwave, Antennas and Optics :: 01-06-2016 08:00 :: G4BCH :: Replies: 4 :: Views: 588
To meet FCC standards and certification in the US for license-free FM transmitters using the standard FM radio band the output can't be more than about 15-20nW, yes it reads nano-W. According to them; it should give you a range of around 200' from the transmitter.
Electromagnetic Design and Simulation :: 11-03-2015 01:44 :: E-design :: Replies: 20 :: Views: 1554
Hello everyone, I need to make 24 to 48 volts; 3 amp maximum from a 12 volt battery. Variable frequency
Thanks for helping up
Power Electronics :: 10-22-2015 01:28 :: bukol123 :: Replies: 10 :: Views: 1164
i think the circuit just does not work for such high frequency
Most of your parts values are for a low frequency because your calculations are wrong.
My FM transmitter uses the same transistor as you and works perfectly at 100MHz and higher. It is a modified Colpitts circuit.
Analog Circuit Design :: 09-08-2015 15:00 :: Audioguru :: Replies: 10 :: Views: 750
I was watching videos about AM and FM on YouTube. I saw a video and can't find it now. In that video was a block diagram-like circuit. It was a physical, actual block circuit. All the blocks like LPF, VCO,BPF etc were built in little metal boxes and these boxes were connected to each other with a coaxial cable and all this system was fixed on a bo
RF, Microwave, Antennas and Optics :: 05-05-2015 22:04 :: Batuhan88 :: Replies: 0 :: Views: 457
I found this interesting video about converting the FM Tx as Rx :
I tried to do the same concept to my FM Tx : tried to simulate the circuit , if R2 resistance is low the circuit doesn't oscillate.
Lets assume I used a high inpu
RF, Microwave, Antennas and Optics :: 03-04-2015 12:04 :: mr_byte31 :: Replies: 3 :: Views: 771
I checked some FM circuits over internet and all seems to miss the band pass filter at the last stage.
This make circuit transmits on all radio channel which is not something nice from my point of view
This circuit operates at 27 MHz and you can see the frequency domain and harmonics on the side of the middle peak
RF, Microwave, Antennas and Optics :: 01-28-2015 13:54 :: mr_byte31 :: Replies: 9 :: Views: 2376
I am just playing with an FM transmitter, I took a simple single transistor FM modulator circuit from online. It is basically the same common base configuration for 88 - 108 MHz oscillator and a mic coupled to the base of same transistor. I added two stages of amplification for the 91MHz signal generated by the above mentioned circuit. I a
RF, Microwave, Antennas and Optics :: 01-07-2015 00:05 :: vinodstanur :: Replies: 2 :: Views: 652
i implemented a 3V fm transmitter circuit from the site
but iam getting constant 60Mhz frequency no matter how much i change the value of trim capacitance.
i used 6.8p instead of 5.6p......will it make much difference?
RF, Microwave, Antennas and Optics :: 11-26-2014 21:27 :: ymmen :: Replies: 4 :: Views: 889
Hi all, I have a question about PCB. Pls help me.
How to integrating 5 Watt FM cỉrcuit (100Mhz) with 0.5 Watt driver in circuit board?
Analog Circuit Design :: 11-18-2014 13:52 :: contau :: Replies: 15 :: Views: 1536
20pF is a capacitor, not a resistor.
In the video the coils are not coils but instead are simply half-loops of wire, a yellow one and a white one. The distortion is VERY high.
There are hundreds of circuits if you go to Google Images and enter: FM regen radio circuit
Analog Circuit Design :: 10-17-2014 14:54 :: Audioguru :: Replies: 1 :: Views: 399
An FM stereo radio is supposed to have brick wall filters to attenuate the 19kHz stereo pilot tone but pass audio frequencies up to 15kHz.
Analog Circuit Design :: 08-11-2014 14:37 :: Audioguru :: Replies: 6 :: Views: 679
Reson why i would like to try transistors or LEDS is that with all that
varicaps which i have i cannot tune whole FM range on easy way....
i need something like BB909...but i don't have this diode
which work ok in area from 0-3V cca (45-32pF)
also i have found on one site where is presented Varicap circuit with
2 ordinary RED LED (5mm)
Hobby Circuits and Small Projects Problems :: 08-11-2014 13:23 :: zlatkoMM :: Replies: 6 :: Views: 2568
A high quality hi-fi FM receiver already has a high gain RF amplifier to be extremely sensitive. If another RF amplifier is used then the receiver simply gets amplified noise.
I agree that a high gain Yagi antenna can increase the signal strength.
Analog Circuit Design :: 08-08-2014 14:43 :: Audioguru :: Replies: 21 :: Views: 1932
Hello. I would like to ask one question about AGC (automatic gain control).
I need to design the LNA with AGC for the FM receiver.
As I know, digital AGC require many control bits and switches which complicate the design, analog AGC has higher resolution than digital ways. Except this point, could you please let me know the pons and cons of
RF, Microwave, Antennas and Optics :: 08-07-2014 07:24 :: sunnybear :: Replies: 2 :: Views: 704
It is the hopeless circuit that I fixed 9 years ago.
1) It oscillates at 106MHz in LTspice IV program but only when it has no antenna. It produces many even harmonics so it causes interference. It stops oscillating when it has an antenna connected to the collector of the oscillator transistor.
2) The 10nF capacitor from the base of the oscillator
Elementary Electronic Questions :: 08-07-2014 14:41 :: Audioguru :: Replies: 16 :: Views: 1486
You forgot to post your schematic.
The simulation probably does not include stray capacitance that together with circuit resistors form lowpass filters.
The resistor values need to be fairly low and the currents fairly high to work at the very high frequency.
Why not use an RF transistor that is used in an FM radio?
Analog Circuit Design :: 07-13-2014 11:47 :: Audioguru :: Replies: 6 :: Views: 903
An LM386 IC is cheap so its has low output power and is noisy (hiss). It can drive a laser diode up to its maximum output power.
The low power and noise might cause a problem in a receiver.
If you simply modulate the light with AM then there will be interference from many things so high fidelity systems modulate the light with FM.
Analog Circuit Design :: 05-13-2014 13:04 :: Audioguru :: Replies: 5 :: Views: 641
Which receiver concept do you try to implement here? Zero IF? What kind of output do you expect for AM and FM modulated signals?
Besides general conceptual problems, the present design will suffer from these:
- no RF is passing the "Low pass filter 3"
- the VCO has a square wave output, so if it's output would be mixed with the antenna input,
Hobby Circuits and Small Projects Problems :: 04-10-2014 05:49 :: FvM :: Replies: 4 :: Views: 630
hi iam new to this forum, and am in search of a good circuit of ba 1404 as an FM transmitter. can anybody help me?
Microcontrollers :: 04-01-2014 09:35 :: arunpradh :: Replies: 1 :: Views: 465
A Varicap is a variable capacitance diode where the amount of its reverse voltage determines its capacitance. When it is parallel with an inductor then the LC in an oscillator can be an FM modulator. A simple transistor can also be used as a varicap and the transistor is the oscillator.
You can find FM demodulator circuits in Google. The latest ch
Elementary Electronic Questions :: 03-24-2014 18:18 :: Audioguru :: Replies: 16 :: Views: 3593
I used a tunnel diode about 50 years ago to make an FM transmitter. I have not seen a tunnel diode since then.
Elementary Electronic Questions :: 02-26-2014 15:01 :: Audioguru :: Replies: 6 :: Views: 996
Yes you can use a ceramic resonator as in the example attached for the TK83361 FM
RF, Microwave, Antennas and Optics :: 01-19-2014 17:39 :: vfone :: Replies: 3 :: Views: 567
More modern FM receivers are available.
Look at the other products too..
RF, Microwave, Antennas and Optics :: 12-22-2013 16:11 :: BigBoss :: Replies: 3 :: Views: 1972
It looks too simple to be an FM receiver circuit. Is it the horrible TDA7000 or newer and also horrible TDA7088 IC?
An FM "radio" with it, headphones and a battery are sold for only ONE DOLLAR at The Dollar Store. Its performance is awful.
Analog Circuit Design :: 12-15-2013 01:05 :: Audioguru :: Replies: 13 :: Views: 4143
A simple radio like this can be aligned for maximum sensitivity. But the automatic gain control on the AM receiver covers up any level changes and an FM radio has the same output level regardless of the signal strength. Then maximum sensitivity is difficult to sense.
If you tap into the IF of another radio then the capacitance of the tap will chan
Hobby Circuits and Small Projects Problems :: 12-06-2013 14:07 :: Audioguru :: Replies: 9 :: Views: 955
You can use any amplifier configuration as a limiter. All it has to do is clip the signal beyond a certain voltage (limit it's range). The idea of a limiter in FM systems is to eliminate as much variation in amplitude as possible so the classic methods are to use a voltage clipping circuit (two diodes in anti-parallel) or an amplifier with such hi
RF, Microwave, Antennas and Optics :: 10-05-2013 08:33 :: betwixt :: Replies: 5 :: Views: 1840
This paper should help you through the design process.
Hobby Circuits and Small Projects Problems :: 08-21-2013 16:22 :: E-design :: Replies: 20 :: Views: 1869
There are many applications of ganged capacitors. Many of them used in circuits that now became obsolete. May be you can post a link to the specific circuit.
For example. Ganged capacitors were used in am and fm radios. One section of the capacitor is used to tune the RF input circuit and the other to set the local oscillator frequency. More (...)
Elementary Electronic Questions :: 08-15-2013 15:40 :: albert22 :: Replies: 5 :: Views: 2952
I see. This transmitter have a FM range from 88 to 95 MHz. And this range relate to VHF range. As we can see in this link:
About the audio amplifier where we find Q1. It contains an active filter RC. Am I right ?
Q1 is a simple a-cl
RF, Microwave, Antennas and Optics :: 08-09-2013 22:05 :: BigBoss :: Replies: 12 :: Views: 3125
am trying to simulate FM transmitter circuit that is using BC547 but I got strange current waveform ! am i missing something? heard that BC547 cant handle the current that mentioned in i
RF, Microwave, Antennas and Optics :: 06-17-2013 18:18 :: xpower :: Replies: 2 :: Views: 2234
I think you will use the 555 as Pulse Width Modulator and put modulation into pin 5 of the 555,
and yes you could do it with small fm tx/rx or maybe infra red or any analog transmitter from any audio source..just have to couple pin 5 and some level adjustment
Hobby Circuits and Small Projects Problems :: 06-08-2013 13:58 :: dian :: Replies: 4 :: Views: 1091
I am not so familiar with Lt spice simulation tool but all the engineers are recommending this tool for simulation....
Is it possible to do any FM transmitter circuit simulation with Lt spice?
I tried it at once but it doesn't work. What's your advise?
Electromagnetic Design and Simulation :: 06-06-2013 11:09 :: udhay_cit :: Replies: 3 :: Views: 2488
The LC tank circuit of the second tank is parallel resonant which produces a fairly high impedance. But the antenna load is a fairly low impedance that widens the resonant peak to cover the entire FM broadcast band without re-tuning.
Hobby Circuits and Small Projects Problems :: 05-29-2013 21:36 :: Audioguru :: Replies: 9 :: Views: 1143
What will be the covering range of MAX2606 FM transmitter?
I am going to transmit my TV signal to my cell phone FM radio & i'm expecting maximum 10Meters range without signal interrupt... Is it suggested for my purpose...
RF, Microwave, Antennas and Optics :: 05-04-2013 09:13 :: udhay_cit :: Replies: 1 :: Views: 1074
as far as i know, here are some notes:
1. in above FM circuit, the C5 and L1 making tank ckt oscillating to generate carrier frequency, now to change the o/p freq, either C5 or L1 or any other external reactive component in vicinity of tank ckt needs to be changed to change the resonant frequency.
2. The change should be fast enough to settle for a
Digital Signal Processing :: 03-19-2013 04:42 :: ashugtiwari :: Replies: 3 :: Views: 757
is there RF transmitter and receiver on Proteus Isis? if there please .....what is the key name of these parts?
Digital communication :: 03-10-2013 15:19 :: mamush2013 :: Replies: 1 :: Views: 4254
An alternative more sophisticated, consider it..
RF, Microwave, Antennas and Optics :: 02-06-2013 16:34 :: BigBoss :: Replies: 7 :: Views: 2632
I need to find the equivalent replacement of mv2109 varactor diode.which parameter i should consider while selecting the replacement?
I am looking for component in digikey & mouser. So please help me to find the available replacement from the supplier.
I need this varactor diode for my FM stereo transmitters circuit (BH1417)...
Thanks & re
Elementary Electronic Questions :: 02-06-2013 12:37 :: udhay_cit :: Replies: 1 :: Views: 1257
I need a simple circuit schematic of two analog modulators. Modulator FM and AM. I have to perform simulation of this in pspice. I search on web any schematics with values of elements, but I can't found working.
Anybody help me?
Sorry for my english.
Thx for help, othername.
Analog Circuit Design :: 02-02-2013 14:18 :: othername :: Replies: 3 :: Views: 1233