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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".
The original circuits are FM, that means the output stage runs at full power 100% of the time. Because the amplifiers run at full power, there is no need for them to be linear. For AM you have to vary the power, thats why its called Amplitude Modulation. If you try to modulate a driver stage there is no guarantee there will be a linear relationsh
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.
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
Is that problem happening whichever the position you lean the board ? I mean, can you determine whether occur an improvement or aggravation of the iterference effect if the FM transmitter is placed close or apart from any stuffs ? In my opinion, you are also facing to issues related to the layout design of the board. As a simple test to check how m
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
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. First.. 0.5-2GHz VCO ( I presume that the modulation will be FM ) is almost impossible. The classical VCOs cover approximately 1 octave not more. Second.. This wideband VCO will have very high
Hi all, 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,
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.
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
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. Q1
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.
Hello everyone, I need to make 24 to 48 volts; 3 amp maximum from a 12 volt battery. Variable frequency Thanks for helping up
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.
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
Hi All, 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
Hi All, 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 www.p
Hi, 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
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?
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?
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
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.
Hi to all... I am interested is there a way to build transistor or LED circuit which act as varicap diodes? We all know that transistor with shot connection between emiter and colector (NPN) respond on reverse voltage and act as varicap. Is there anyone with experience in this area? Or someone who already build such a LC tank in first place
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.
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
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
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?
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.
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,
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?
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
I used a tunnel diode about 50 years ago to make an FM transmitter. I have not seen a tunnel diode since then.
I would guess in this case 'quad' is shortened from 'quadrature'. Is is part of an FM discriminator circuit? Brian.
I want to make a powerful FM radio/ receiver without any noise. It's for my electronis project. I learnt that TDA7000 is a bulit in IC for FM Receiver. But I need more information and specific circuit diagram for a noise free high amplifier radio device. help me for making it. Thanks in advance.
Hi, all I want to learn how to design high frequency circuit, so I draw this FM radio receiving circuit, could you give me some advise to revise it? How to do PCB layout and routing, could you give me some materials. Thanks! Sincerely, zhe
Hi I bought an Fm receiver kit recently. It has two ICs. The first is a TA8127N which is the front end of the receiver and includes the stereo decoder. I assembled the kit and it works but I am not sure how to align it. There are two coils and two transformers. The instructions that came with the kit are in Thai. Is it possible to
Hi, Can a differential amplifier can be used as a limiter circuit for FM demodulation ? Can anybody explain the circuit, if it exixt !! Thanks
Hello every body I want to now how can I build my own Fm circuit , I now there is a lot of prepared circuit but I want to build my own . I will be glad if you have any book or link that can help me , I already finish my electronics course and one communication course , but unfortunately I'm not able to construct this kind of circuit in (...)
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 (...)
Hi everyone, I need some help to describing walkie talkie circuit diagram. I know where is the oscillator, antenna, one or two filters... But some components I don't know theirs functions. For instance: In the transmitter. We have C4 and R4 in parallel. Is a filter or not ? transmitter:
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
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
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?
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.
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... Regards Udhay
Hi, I'm new here, I have a little problem, I'll be grateful for the help. It happens that I want to modify the circuit of an FM audio transmitter, so that instead of transmitting audio can transmit a signal to turn off or turn on a switch, and the switch on and off an LED, the idea is to communicate using Morse code using the FM frequency. What co
hello there! is there RF transmitter and receiver on Proteus Isis? if there please .....what is the key name of these parts? thanks!!
Dear friends, I need to build a stereo fm transmitter using BH1417 chip. Before starting my design, i have some doubts.... 1. Is it the crystal 7.6Mhz or 7.68Mhz...? some of the website shows schematic with 7.68Mhz. is it acceptable...? 2. How to select equivalent varactor diode? Can anybody give me the part number available i
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
Hello, 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.