This page provides soft power switch circuits for toggling electronic devices ON and OFF with a momentary button press that controls a latching high-side MOSFET power switch. Several micropower latching switch circuits are provided. Owing to their low current in the OFF state, they`re well suited to battery operated portable instruments. Feel free
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to use these circuits as is, or modify them for your needs, wherever you might need a power bus switch circuit. The soft power switch circuit designs shown on this page provide both functions. You may also be interested in ON/OFF switches that limit capacitor in-rush currents, or switches to specifically turn ON/OFF microcontroller products. Using a single tactile switch button to alternately toggle a circuit ON and OFF requires a circuit containing a bistable logic latch. Such a latch can be implemented using a D flop flop, or by using positive feedback around any two inverting amplifiers or logic gates. For example, a basic latching ON-OFF switch can be implemented using a dual NAND gate, using this circuit: A brief button press toggles the output state of this NAND gate latch. Any CMOS NAND gate can be used, including Schmitt trigger gates. In fact, any inverting devices can be used with minor changes to the circuit: a hex inverter, open collector inverters, NAND or NOR gates, transistors, FETs or MOSFETs. When power is first applied, the capacitor at the input of the first gate guarantees that the latch output, Vout, is initially latched low. Thereafter, button presses toggle the output high and low. This circuit uses only a single active device, the surface mount dual MOSFET, yet toggles ON and OFF currents of up to 4 Amp. The load may be just about any electrical device, from high power LED lights to the power supply...
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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