This circuit, which uses a CD4538 retriggerable monostable multivibrator and a CD4011 NAND chip, can sense fluid levels using a variable capacitance ( see the figure ). Such a sensor can be as simple as two adhesive copper foil strips on a saline or blood-supply bag or on another nonmetallic container. These strips should be as close together and
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as long as possible, since C ‰ • (A/L). When the fluid level is low (CX = C0), the oscillator`s frequency is high enough so that the trigger input (+TR2) keeps that half of IC2 retriggered, i. e. [overbar Q2] is kept low. As the fluid level rises, so does C, and in turn the frequency goes down. Potentiometer R3 with capacitor C3 sets the level at which the retriggering is no longer continuous. Therefore, what might look like positive pulses at [overbar Q2] are actually "dropouts" from the low state. As long as the frequency is low enough, these pulses will appear at +TR1, keeping the second half of IC2 retriggered for appropriate values of R4 and C2. Typical values of 50 to 100 pF for CX will produce an oscillator frequency of 10 to 30 kHz, depending on stray capacitance.
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....
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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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