This is aquiz bell/alarm circuit. This circuit indicate fastest finger first . This circuit has one bulb for Quiz master and one for each contestant. The bulb will illuminate when a button is pressed. the cathode of the 9v1 zener sees approx mid-rail voltage. The Quiz Master bulb is also illuminated. Here is the circuit: There is no other bulbs
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can be lit until the circuit is reset because The zener comes out of conduction and no voltage appears across the 120R resistor. The reset switch must be a normally closed push button, to disconnect the power supply when it`s being pressed. A pair of cross-coupled SCRs can be used to build a first-response monitor circuit, as shown in the schematic diagram below. First-response circuit is popular in quiz application where the first contestant who press the button will prevent the other Continue reading †’. This is a switching circuit that provide latching mechanism to make a set of radio buttons using push buttons. This circuit consist of interlocking circuit that manipulate the signal to latch and release the previous latched section. The circuit latches Continue reading †’. The figure below show us a zener regulator. The essential component is the dropping resistor R which the value given by (V-Vo)/I, where I is the desired output plus 10%. As long as the supply voltage V is constant, the Continue reading †’. This is a little audio amplifier, it is similar to the audio amplifier which is used in small transistor radio. This circuit draws about 30 milliamps from a 9 volt supply. This circuit consist of two stage. First stage is Continue reading †’. WARNING: Don`t touch any part of the circuit when the circuit is running (connected to the powerline), this circuit is not isolated from mains supply. This is transformerless...
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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