Wall sockets supply power in the form of a 230 volt sine wave. The frequency of this sine wave is supposed to be 50 hertz. In other words, the voltage on the socket alternates between positive and negative at a rate of 50 full periods per second. (At least this is how it works in the Netherlands; many countries use different frequencies and/or voltages. ) There
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are clocks, so-called synchronous clocks, that count voltage alternations to determine the passage of time. Is the grid frequency accurate enough to keep such clocks running right I used an Arduino to measure the frequency of the sine wave from a wall socket. To avoid working with dangerous high voltage, I used a transformer from an old halogen lamp. The transformer is plugged into the wall socket, and the low voltage side of the transformer is hooked up to the Arduino through a resistor network. The Arduino measures the sine wave at about 4386 samples/s. Whenever it detects a rising zero-crossing edge in the sine wave, it sends a timestamp to the PC. Some kind of reference clock is needed to measure the frequency of a signal. The Arduino has an on-board clock crystal but I was not sure about it`s accuracy. So I decided to use a GPS receiver as my reference clock. It generates a pulse per second (PPS) with very high accuracy. The GPS receiver is connected to the Arduino by means of LadyAda`s excellent GPSshield. When the Arduino detects a time pulse from the GPS receiver, it sends a timestamp from its on-board clock to the PC. Software on the PC uses these timestamps to detect variations in the rate of the Arduino board clock. The GPS signal is not strong enough for indoor reception unless the receiver is very close to the window, so I built the test setup in the window sill. I let it run for 8 days while recording data 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....
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....
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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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