Showing posts with label fm. Show all posts
Showing posts with label fm. Show all posts
Wednesday, 10 April 2013
Wave antenna 5 8 pro VKV FM
Wave antenna 5/8 consists of a vertical radiator which is fed at the base of the antenna. A suitable device of some sort should be added between the antenna and feedline if you want to eat with coax. Adding a coil in series with the antenna on the base is one of these methods are suitable.
So why would anyone use an antenna 5/8 wave if they have to go through all that extra work? After all, a ground plane antenna provides a good match. There are several answers. The first is GAIN. The computer shows that the antenna (mounted 1 foot above the ground) has a margin of about 1.5 dBd higher than a dipole (also installed 1 foot above the ground.)The second reason you might want to use the wave 5/8 vertical is to get a lower angle of radiation. Peak radiation angle A half-wave antenna is 20 degrees. You will find that the angle 5/8 wave antenna radiation is only 16 degrees so it is better dx antenna.
You may have noticed a pattern developing here. A quarter-wave ground plane antenna has a radiation pattern that produces the maximum gain at about 25 degrees and half-wave antenna drops to 20-degree angle, and wave antenna 5/8 further drops to 16 degrees angle. So why not just keep extending the antenna to one full wave? Well it would be nice if it worked, but unfortunately the wave patterns begin to create a very high angle of radiation waves exceed 5/8. So weve reached the maximum gain at this point and extend the antenna further reduce profits only where we want it (low angle).
Of course if you are interested in a very short jump, extend the antenna will produce a nice profit on the dipole.All the length of the antenna depends on various factors. Some of these factors are: height above ground, the diameter of the wire, nearby structures, the effects of other antennas in the area and even the conductivity of the soil.This page allows you to calculate the wavelength for the antenna 5/8. It uses the standard formula, 585 / f (178.308 / f for metric) MHz to calculate the length of the element. If you have experimented with 5/8 wave antenna before and know a better formula for your QTH, feel free to change the formula accordingly. This formula is for the antenna wire.
Of course if you build your antenna out of the tube, total length of the antenna will be shorter, for example I have found that 21.5 feet seems to provide maximum benefit to the frequency of 28.5 MHz when using a 1 "tube, and 22.5. Foot seems be the best long-wire at the same frequency. Since the formula to calculate the antenna to be about 2 feet shorter, be sure to experiment and maybe add a little for your final term.
Tuesday, 26 March 2013
FM Telephone Bug Circuit
Here is a simple transmitter that when connected to a phone line, will transmit anything on that line (execpt the dial tone) to any FM radio. The frequency can be tuned from 88 to about 94Mhz and the range is about 200 feet. It is extremely easy to build and is therefore a good, useful beginner project.
FM Telephone Bug Circuit diagram:
Parts:
R1 180 Ohm 1/4 W Resistor
R2 12K 1/4 W Resistor
C1 330pF Capacitor
C2 12pF Capacitor
C3 471pF Capacitor
C4 22pF Capacitor
Q1 2SA933 Transistor
D1, D2, D3, D4 1SS119 Silicon Diode
D5 Red LED
S1 SPDT Switch
L1 Tuning Coil
MISC Wire, Circuit Board
Notes :
1. L1 is 7 turns of 22 AWG wire wound on a 9/64 drill bit. You may need to experiment with the number of turns.
2. By stretching and compressing the coils of L1, you can change the frequency of the transmitter. The min frequency is about 88 Mhz, while the max frequency is around 94 Mhz.
3. The green wire from the phone line goes to IN1. The red wire from the phone line goes to IN2. The green wire from OUT1 goes to the phone(s), as well as the red wire from OUT2.
4. The antenna is a piece of thin (22 AWG) wire about 5 inches long.
5. All capacitors are rated for 250V or greater.
6. The transmitter is powered by the phone line and is on only when the phone is in use. S1 can be used to turn the transmitter off if it is not needed.
7. If you have problems with the LED burning out, then add a 300 ohm 1/4W resistor in series with it.
FM Telephone Bug Circuit diagram:
R1 180 Ohm 1/4 W Resistor
R2 12K 1/4 W Resistor
C1 330pF Capacitor
C2 12pF Capacitor
C3 471pF Capacitor
C4 22pF Capacitor
Q1 2SA933 Transistor
D1, D2, D3, D4 1SS119 Silicon Diode
D5 Red LED
S1 SPDT Switch
L1 Tuning Coil
MISC Wire, Circuit Board
Notes :
1. L1 is 7 turns of 22 AWG wire wound on a 9/64 drill bit. You may need to experiment with the number of turns.
2. By stretching and compressing the coils of L1, you can change the frequency of the transmitter. The min frequency is about 88 Mhz, while the max frequency is around 94 Mhz.
3. The green wire from the phone line goes to IN1. The red wire from the phone line goes to IN2. The green wire from OUT1 goes to the phone(s), as well as the red wire from OUT2.
4. The antenna is a piece of thin (22 AWG) wire about 5 inches long.
5. All capacitors are rated for 250V or greater.
6. The transmitter is powered by the phone line and is on only when the phone is in use. S1 can be used to turn the transmitter off if it is not needed.
7. If you have problems with the LED burning out, then add a 300 ohm 1/4W resistor in series with it.
Source : http://www.ecircuitslab.com/2011/06/fm-telephone-bug-circuit.html
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.
Read More..
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.
Subscribe to:
Posts (Atom)
