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Wideband Active Antenna Circuit
A 30 to 50 cm whip antenna provides reception from 10 MHz to over 220 MHz. T1 BF981, a dual-gate MOSFET, provides low noise, high-input impedance and high..
VHF Audio Video Transmitter
The circuit presented here is a simple audio/video transmitter with a range of 3 to 5 metres. The A/V signal source for the circuit may be a VCR, a satellite receiver or a video game etc. A mixer which also operates as an oscillator at VHF (H) channel 5 TV frequency is amplitude modulated by video signal and mixed with frequency mo enna, contains
FM voice transmitter for Band 2 VHF
This small transmitter uses a hartley type oscillator. Normally the capacitor in the tank circuit would connect at the base of the transistor, but at VHF the base emitter capacitance of the transistor acts as a short circuit, so in effect, it still is. The coil is four turns of 18swg wire wound around a quarter inch former. The aerial tap is about
HF VHF receiver diplexer
An Icom PCR-1000 listening to various MF, HF and VHF radio stations. However, there is a slight problem. Very slight, almost too small to even mention, more of an inconvenience than a problem. Still, if I am being inconvenienced, than others are too. This issue is with the antennas. My K9AY antenna works wonderfully from 500 KHz to 25 MHz or so....
HF/VHF LCD PIC16F88 SWR Bridge
2SC1946A 30 Watt VHF Amplifier
The 30 watt amplifier schematic shown below provides an appropriate power boost with an input of 4 watt up to 6 watts. The circuit is designed to cover 88-108MHz FM Broadcast Band. However, the circuit is very stable at my place and provides a clean-output through seven (7) element Butter-worth low-pass filter. The heart of the circuit is 2SC1946A
VHF/UHF TV TRANSMITTER PLL
Opamp VHF FM Transmitter circuit
This opamp is available for only a few pounds. The AD8099 is a very fast opamp (1600 V/ms) and has high-impedance inputs with low input capacitance. The bandwidth of the opamp is so largethat at 100 MHz it still has a gain of nearly 40. This means that this opamp can be used to create an RC oscillator. The circuit presented here realises that....
Meteor Scatter obs with VHF Radio & Computer
This page contains material related to the technical issues on taking meteor counts thus monitoring the meteor influx using VHF radio receivers. It is not meant to be a comprehensive how-to guide, but tries to fill some gaps and give second opinions on observing techniques partially based on some real data presented here. There are plenty of sites
Opamp VHF FM Transmitter
ICs that in the past were far too expensive for the hobbyist tend to be more favourably priced these days. An example of this is the AD8099 from Analog Devices. This opamp is available for only a few pounds. The AD8099 is a very fast opamp (1600 V/ms) and has high-impedance inputs with low input capacitance. The bandwidth of the opamp is so large
Single-Chip VHF RF Preamp
Here is a high performance RF amplifier for the entire VHF broadcast and PMR band (100-175 MHz) which can be successfully built without any special test equipment. The grounded-gate configuration is inherently stable without any neutralization if appropriate PCB layout techniques are employed. The performance of the amplifier is quite good. The no
vhf transmitter 5 pin input jack wiring
VHF Twist-Shift Keying Rotation-Shift Keying Orthogonal BPSK Twist Modulation Motorola SyntorX
The material in this section shows how we built the Twist-Shift system for VHF using commonly available (and cheap) surplus land mobile VHF transceivers modified to operate on the 2-meter ham band. The radios we used were the 100-watt Motorola SyntorX model. The radios were additionally modified for the Twist-Shift experiments as described below.
vest pocket vhf fm test generator
VHF & UHF universal frequency meter
Triode Frequency Conversion at FM-VHF
VHF FM Crstal Set Radios
Phase-sensitive detectors usually take the difference between an input FM signal and the same signal after it has passed through a resonant circuit, or through a delay line. A 1N34 should work fine to detect 100MHz, but not all 1N34 diodes are made alike. One with low internal resistance and low capacity would be best. Some fancy shottky diodes...
VHF MODULATOR circuit
Developed as interface between General Instruments AY-3-8500-1 TV game chip and antenna terminal of TV set. Adjust C1 to frequency of unused channel to which receiver is set for playing games. Article gives all circuits but covers construction only in general terms.-S. Ciarcia, Hey, Look What My Daddy Built!, 73 Magazine, Oct. 1976, p 104-108..
The recommended Prescaler is ridiculously simple. It consists of just one IC, a TV tuner prescaler, the Philips SAB6456A, which can divide by 64 or by 256. This chip is widely available both new and in the surplus market at much lower prices than conventional divide by prescalers..
VHF/UHF TV Modulator
Simple oscillator that generates a frequency in the VHF or UHF region. The oscillator is modulated with the video signal and the modulated carrier wave thus generated is fed into the TV set`s aerial input via a cable. Then all that remains to do is tune the TV to the correct frequency..
VHF 0.5 W TV Transmitter
The TV transmitter introduced here can send audio and video signals of satellite television receivers, VCDs and video recorders in open circuit, and receives signals with open antennas. It is suitable for self-made programs of working units, schools, and factories. When folded dipole antenna is used to send signals, the covered distance is...
Active Antenna for HF-VHF-UHF
Camera VHF Video Transmitter
This is a simple video transmitter that can transmit as far as 50 meters. This video transmitter can be used with the camera or other video sources. You can view them on VHF channel analog TV. Supply voltage to the video transmitter can use 9V battery. Transistor components that are used for a video transmitter is BC548 or you can use another...
VHF-band FM Circuit of Variable Capacitance Diode
Circuit`s Functions The frequency modulation FM transmitter which can be used in 76~90MHZ FM radio band, usually also it is called wireless microphone.It adopts signals via FM radio receiver.The signals can be transmitted in wireless means if we don`t use the microphone but input low frequency signals.The transmitting distance can reach over 30...
VHF FM Transmitter MAX2606
If you want to be independent of the local radio stations for testing VHF receivers, you need a frequency-modulated oscillator that covers the range of 89.5 to 108 MHz ? but building such an oscillator using discrete components is not that easy. Maxim now has available a series of five integrated oscillator building blocks in the MAX260x series...
VHF Overtone Oscillator
VHF overtone crystals can be difficult to use due to the many frequencies at which the crystal is perfectly happy to oscillate. A typical 100 MHz, 5th-overtone crystal will oscillate at approximately 20 MHz, 60 MHz, 100 MHz, and even 140 MHz, not to mention other, unintended modes that such crystals often have. Most VHF overtone oscillators use...
The VHF antenna switch
Finally I have found a use for a bunch of DIP-style RF relays I acquired in a grab-bag from a discount electronics shop some time ago. These babies are sealed totally, and rf shielded with low contact capacitance. Perfect for VHF frequencies. They are 12 volt and have a fairly decent coil resistance, although I wish they were latching style. I hav
20 MHz VHF CRYSTAL OSCILLATOR
A typical circuit at 20 MHz is shown. The crystal, which has an internal series resistance RS, of 14 ©, oscillates at its third harmonic. The diode clamp D1 and D2 provides a constant amplitude control. The transistor operates continuously in a linear mode over a complete cycle of oscillation, and reflects a reasonably constant load across the c
FM Radio Circuits
RF Transmitter Circuits
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FM Transmitter Circuits
Ultrasonic distance finder circuit
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
Digital Signal Integrity
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