This wideband jammer simultaneously blocks all transmissions within a desired band typically by sweeping across the desired band to be blocked, starting at the lowest frequency and ending at the highest frequency of the band. For this purpose a linear sawtooth signal is applied to the modulator in the FM transmitter described here. The transmit
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ter uses varactor diodes in the tuning circuit to determine the transmitters frequency of operation. Applying a sawtooth signal to the varactor diodes results in the transmission frequency changing with respect to the changing voltage of the sawtooth. As the voltage of the sawtooth signal increases so does the frequency at which the transmitter transmits. This cycle is repeated many times a second. A sawtooth signal generator is shown in Below figure. To ensure the jamming signal sounds natural, white noise is added to the sawtooth signal. To improve stability, consider feeding power to the Operational Amplifiers seperately be means of a voltage divider for each (use the same component values as shown in the schematic). For experimentation purposes and to prevent unwanted interference, connect the output of the transmitter to a 50 Ohm/10 W resistor dummy load. In practice the transmitter would be connected to a wideband VHF antenna (but that may be illegal). To match the impedance between the transmitter and antenna/ dummy load adjust the two trimmer capacitors in the last stage until the best match is obtained. To measure the SWR use a SWR meter. A SWR of 1:1. 5 or better can easily be achieved when connecting the transmitter to a 30 MHz to 800 MHz discone antenna (a wideband antenna such as a discone or similar is recommended for best results). The adjustment of the trimmer capacitors is not described here,...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
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....
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....
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....
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....
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,....
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....
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....
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.....
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