This timer can be inserted in a power line to provide a controllable delay before a load is energized. The mains voltag
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e is reduced by C3 and rectified to give about 30 V across CI. This potential charges C2 slowly via R4/P1. When UC2 reaches about 14 V, electronic switch T1/T2 actuates a solid-state relay (a Sharp S202DS). When the mains voltage is removed, C2 discharges rapidly via D6 and RIO. The delay extends from 15 s (PI set to minimum resistance) to 5 min (PI set to maximum resistance). The solid-state relay needs cooling in accordance with the current drawn by the load: at up to 1 A, no heatsink is required; at 1 to 3 A (max), a 55 cm heatsink is advisable. During the building of the circuit, consideration must be given to safety because many parts will be at mains potential. For instance, fitting the unit in an ABS or other man-made fiber enclosure is a must. If a potentiometer is used for PI, its spindle should be insulated. If a preset is used, it must not be accessible through a hole in the enclosure. Switch SI is a DPST that disconnects the circuit from the mains. Nevertheless, the only way to safely work on the circuit is to unplug the mains socket and allow C3 sufficient discharge time.
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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