The GDO originally used a triode vacuum tube configured as an oscillator, with a sensitive DC current meter measuring its grid current. Most versions found today are solid state (JFET) and have no grid (or grid current), but the name has stuck. This schematic shows an example of a GDO. In this circuit, L1 resonates with C1, creating an oscillation
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. In operation, the RF energy in L1 couples into a tuned circuit under test. When the circuit under test absorbs energy from L1, the gate current in Q1 drops, causing the needle on M1 to dip. L1 plugs into the circuit because GDOs come with a set of inductors to cover several bands of frequencies. A network analyzer normally has neither a meter nor an external coil for an oscillator. To get the network analyzer to operate like a GDO, we try to couple the S11 port of the network analyzer to the circuit under test and look for a shift in the impedance level. As with any GDO, there must be a strong coupling between the instrument and the load to get a noticeable dip . Use a wire loop probe mounted to the end of a coaxial cable to couple the network analyzer to the circuit under test. The exact design of the loop depends on the frequency range of interest. Try to make the loop with a Z of 30 to 70 ohms for best results. Since this application requires strong coupling, the shape factor of the loop depends on physical properties of the circuit under test.
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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