This design combines power-on and low-battery indication, can operate with any battery voltage up to 15V, has very low current drain (2mA or less) and costs less than $3. 50 with new parts. When the battery voltage is above a predetermined minimum, power on is indicated by what appears to be a steadily lit LED. In fact, the LED is being pulsed by a
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free-running relaxation oscillator formed by IC1c, one gate of a 4093 CMOS quad Schmitt NAND. The frequency of this oscillator should be at least 50Hz, so that it appears to be continuously on while at the same time drawing far less average current than a steadily lit LED. The series resistor for the LED needs to be selected for each battery voltage, to limit the current to a safe vale or you could use a fixed resistor and a series trimpot for flexibility. Low battery voltage is indicated by the LED pulsing at around 1Hz. The battery voltage is monitored by transistor Q1 and trimpot VR1. Once the voltage at its base falls below 0. 6V, Q1 turns off and Q2 turns on to enable the 2-gate oscillator formed by IC1a and IC1b, which runs at 1Hz. The pulses from this oscillator are inverted by IC1d to gate the LED oscillator on and off. Calibration can be done with a variable bench power supply set to the lowest battery voltage you will accept. Power up the circuit and adjust VR1 until the LED pulses once per second.
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....
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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