A very simple Field Strength Meter composed of a small antenna, a detector diode, a resistor, capacitor and a Micro Ammeter. Assuming that this simple circuit would be sensitive enough to detect the HF field, providing we keep it close enough to the transmitting antenna. This worked quite well, and the intermittent problem was easily diagnosed and fixed;
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it was caused by a broken antenna cable, making intermittent contacts. With the meter we were able to see a clear drop of the field strength when moving the cable. From there, the technical curiosity took over; what if we could improve the circuit, making it more sensitive and, how high in frequency it would still work Would it work for much higher frequencies such as 2. 4 GHz, to check RF fields from Wi-Fi routers and mobile phones I gave up (at least temporarily!) to the idea of building a wide range RF amplifier to amplify the antenna signal over that wide range of frequencies. This might be another project for another rainy Sunday (or many more rainy Sundays!). Instead, I preferred trying to amplifying the DC signal after the RF detection and see how far we can go. And here we go; we have a very simple instrument that can detect the activity of your Wi-Fi router, your mobile phone and about any RF transmitter through a wide range of frequencies. It is powered by a 9 V battery. The diode is a critical component; it should have a low threshold voltage. The diode used in this circuit is a germanium diode 1N60. A ghost from the past, but it is still available on the market (Escol for example). The diode and the 1 nF capacitor are soldered directly at the base of the antenna connector. In the next version of this circuit I would put the 100 K resistor there as well. Another critical point is the antenna. It should be cut to...
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....
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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....
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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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