With pulse operation, the solenoid is energized momentarily with five to six times its rated voltage, then held in with less than half of its rated voltage. Application time is reduced drastically and the reduced holding voltage produces less arcing when the circuit is opened. Additionally, a well regulated d-c power supply is not required. With switch S open, capacitor C charges to the line voltage value, VL. If a 24vdc
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solenoid is used with a 120vdc line, the solenoid receives five times its rated voltage when the switch is closed. After switch closure, solenoid voltage, Vs drops sharply due to resister R. Since power varies with the square of voltage, reducing the holding power to 1/2, reduces power dissipation to 1/4. Because poor regulation is permissible, a simple half wave rectifier converts the a-c source to a d-c voltage. Capacitor C charges to the peak line voltage at approximately 160 volts, for a standard 115 volt line. Operation from a dc source is the simplest CASE, Fig. 1. After selection of a solenoid rated at approximately 20% of available peak line voltage, values of R and C must be determined. Resistance determines the holding current. Most solenoids in the 9 to 12 watt range will remain energized at 10% to 20% of rated voltage. Limiting voltage to 1/2 to 1/3 rated voltage assures sufficient holding force. Resistance R is calculated from: Where VL is line voltage, Vs is required solenoid holding voltage, and Rs is solenoid coil resistance. To hold a 24vdc solenoid at 1/3 rated voltage ( 8vdc): Capacitance requirements for the pulse operation circuit are not so easily determined. The capacitor must store sufficient energy to establish the required magnetic field in the solenoid; this field must persist long enough to accelerate the moving parts actuated by the solenoid. The solenoid will not remain energized if the...
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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