Showing posts with label transmitter. Show all posts
Showing posts with label transmitter. Show all posts
Tuesday, 26 March 2013
25 Metres Range Short Wave AM Transmitter
Here the short wave AM Transmitter circuit design diagram. The circuit is quite simple and easy to build since it applies only a few electronic components. The primary feature of this transmitter is that it really is absolutely free from the LC (inductor, capacitor) tuned circuit and runs using a fixed frequency of 12 MHz that is very stable. An LC based tuned circuit is inherently unstable because of drift of resonant frequency due to temperature and humidity variations.
25 Metres Range, Short Wave AM Transmitter Circuit diagram :
Resistors R1 and R2 are utilized for DC biasing of transistor T1. The capacitor C1 gives coupling in between the condenser microphone and the base of transistor T1. In the same way, resistors R3, R4 and R5 give DC biasing to transistor T2.
The oscillator segment is a combination of transistor T2, crystal XTAL, capacitor C2, C3 and resistors R3, R4 and R5. The crystal is excited by a portion of energy from the collector of transistor T2 via the feedback capacitor C2. The crystal vibrates at its essential frequency and the oscillations happening because of the crystal are placed to the base of transistor T2 across resistor R4. Using this method, continuous undamped oscillations are acquired. Any crystal having the frequency in short wave range could be substituted in this circuit, even though the operation was tried using a 12 MHz crystal.
The Transistor T1 has 3 capabilities:
- The transistor features the DC path for extending +VCC source to transistor T2.
- It amplifies the audio signals which is generated by condenser mic.
- It injects the audio signal into the high frequency carrier signal for modulation.
The transmitted signals could be received on any short wave receiver without having distortion and noise. The range of this transmitter is 25 to 30 metres and may be expanded even more in case the length of the antenna wire is suitably extended together with good matching.
Monday, 25 March 2013
FM wireless transmitter circuit
This the fm wireless transmitter circuit, the truth is one kind microphone that developed to be used without a cable from the microphone to the amplifier. Makes flexible to use than a plain microphone much Because without cumbersome cables. And also save a microphone cable as much Because microphone cable is high quality that has relatively high prices.
How it work
When we speak, the microphone will receive the audio signal is mixed with range FM frequency to transmit the broadcast spectrum. The audio input is just bring to the FM radio receiver tuned provide the radio only. The detailed procedures are as follows.
In Figure this circuit has very little equipment, MIC is used in the circuit be special that called the condenser microphone, inside the MIC has an one amplifier section Serves to amplify the voice that speaks to the strength increases and send to the output. So this MIC must a current one to them. Please note the circuit is supplied to the resistor 27K positive in the leg microphone,and it is way out of with the audio signal,through the coupling capacitor to pin B of Q1,
Which Q1 also acts as both the radio frequency generator and the audio mixer on the Radio frequency is generated. and at B pin of the Q1 have the resistor R2 – 27K with R3 – 4.7K are divider circuit, Divided a number of voltage to the bias for Q1. and the capacitor C2-0.01uF is connected to ground for bypass the high frequency, At C pin of the Q1 is connected pass the coil to the positive voltage
For this coil, we use copper wire No. 19-20 AWG, wrapped around the air core diameter of 7 mm. You should be bind seven around , similar to coil spring, Then, stretching out to Length of 15 mm. close this coil has a capacitor C4 value 5-20pF is the capacitor to adjust from 5pf to 20pF we called that the timmer. It is connected to a frequency tuning
And pin C of Q1 is connected to the antenna. Which in this circuit, we use an antenna that is built with yourself. By using number of wire 16-20 AWG, about 7 inches in length, and curled into a circle like a spring, about 6 mm in diameter, the length of the wire coil to the the end, then take one end soldered to the antenna connection.
Creating and use
You should be include before small device. The condenser MIC should be use the shielded cables in length about 5 cm to connect from the PCB. We use the coated copper wire for to prevent rust green from moisture in the air. At the end of the wire must be soldered, the need for razor blade to scrape out a solution. so is soldered on. The use of lead solder, lead to a better mix of 60/40, and requires some skill in soldering. Otherwise, the spectrum could not be removed. It is a high frequency.
When completed, the FM radio is one, open to the FM radio dial in the middle. When turn on the FM wireless transmitter circuit then use a screwdriver plastic or plastic sheet flat spin adjust the trimmer And speak into the microphone, to tune until has the sound to the FM radio. if tune the trimmer until full cycles, Not yet match wave, try stretching or shrinking of the coil, then adjust the new one, maybe try some stretching or shrinking the antenna, in order to deliver the best results. If all the fine tuning do still does not work. Also, try turning the radio waves, may be rotated to the minimum frequency, maximum frequency, or turn around the station. Then try adjust it again. When adjust until available, they may be find a plastic boxes or aluminum boxes or a box ready to build up own. By folding a sheet of aluminum or a plastic sheet is glued to the box for convenience to you.
Note: Principle, this circuit send far about 100 meters, Depending on the location. There is low or high of noise oscillator, Equipment with high quality or not, The soldering is good or not, Therefore, it is difficult to determine how far? But from my experience, in the center of the floor to the fourth floor of the building, it has been, they think that’s enough for the circuit with very little equipment, and low cost of this.
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How it work
When we speak, the microphone will receive the audio signal is mixed with range FM frequency to transmit the broadcast spectrum. The audio input is just bring to the FM radio receiver tuned provide the radio only. The detailed procedures are as follows.
In Figure this circuit has very little equipment, MIC is used in the circuit be special that called the condenser microphone, inside the MIC has an one amplifier section Serves to amplify the voice that speaks to the strength increases and send to the output. So this MIC must a current one to them. Please note the circuit is supplied to the resistor 27K positive in the leg microphone,and it is way out of with the audio signal,through the coupling capacitor to pin B of Q1,
Which Q1 also acts as both the radio frequency generator and the audio mixer on the Radio frequency is generated. and at B pin of the Q1 have the resistor R2 – 27K with R3 – 4.7K are divider circuit, Divided a number of voltage to the bias for Q1. and the capacitor C2-0.01uF is connected to ground for bypass the high frequency, At C pin of the Q1 is connected pass the coil to the positive voltage
For this coil, we use copper wire No. 19-20 AWG, wrapped around the air core diameter of 7 mm. You should be bind seven around , similar to coil spring, Then, stretching out to Length of 15 mm. close this coil has a capacitor C4 value 5-20pF is the capacitor to adjust from 5pf to 20pF we called that the timmer. It is connected to a frequency tuning
And pin C of Q1 is connected to the antenna. Which in this circuit, we use an antenna that is built with yourself. By using number of wire 16-20 AWG, about 7 inches in length, and curled into a circle like a spring, about 6 mm in diameter, the length of the wire coil to the the end, then take one end soldered to the antenna connection.
Creating and use
You should be include before small device. The condenser MIC should be use the shielded cables in length about 5 cm to connect from the PCB. We use the coated copper wire for to prevent rust green from moisture in the air. At the end of the wire must be soldered, the need for razor blade to scrape out a solution. so is soldered on. The use of lead solder, lead to a better mix of 60/40, and requires some skill in soldering. Otherwise, the spectrum could not be removed. It is a high frequency.
When completed, the FM radio is one, open to the FM radio dial in the middle. When turn on the FM wireless transmitter circuit then use a screwdriver plastic or plastic sheet flat spin adjust the trimmer And speak into the microphone, to tune until has the sound to the FM radio. if tune the trimmer until full cycles, Not yet match wave, try stretching or shrinking of the coil, then adjust the new one, maybe try some stretching or shrinking the antenna, in order to deliver the best results. If all the fine tuning do still does not work. Also, try turning the radio waves, may be rotated to the minimum frequency, maximum frequency, or turn around the station. Then try adjust it again. When adjust until available, they may be find a plastic boxes or aluminum boxes or a box ready to build up own. By folding a sheet of aluminum or a plastic sheet is glued to the box for convenience to you.
Note: Principle, this circuit send far about 100 meters, Depending on the location. There is low or high of noise oscillator, Equipment with high quality or not, The soldering is good or not, Therefore, it is difficult to determine how far? But from my experience, in the center of the floor to the fourth floor of the building, it has been, they think that’s enough for the circuit with very little equipment, and low cost of this.
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