The circuit within the dotted line for a mini emergency light can be incorporated into any battery eliminator, provided the eliminator`s voltage is higher than the battery`s voltage. For greater load (1. e. for more light through a b1gger lamp), Tl should be a power transistor such as ADl49. Diode in the circuit prevents the flow of current from ba
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ttery in the emergency light to the radio during power failure. It is enough to use the switch in the radio set to tum it off. The following circuit of a simple LED flasher can be used for any indication purpose in stereo amplifiers, tape recorders, fancy dolls etc. All components are locally available and the project would cost about Rs 12 only, apart from power supply. A Schmitt trigger provides regenerative switching, and Rl gives the necessary charge/ discharge bistable action as Tl is switched on and off. R3 and R4 set the on` and off` times respectively. Brightness of the LED is set by Rl and Vg Depending upon the capacitor, the R-C time constant can be adjusted. lC3 is similarly fed from IC2. The contents of each decade counter are taken in BCD (binary coded decimal) form, fed through IC 7447 BCD to 7- segment decoder driver and displayed on the corresponding FND 507 LED display. These shaped pulses_are counted by three decade chain counters using three 7490 ICs. Input is given to pin I4 of ICI and output from pin ll of this IC is fed to pin I4 of IC2. Thus the contents of ICI, IC2 and lC3 are displayed one Ll (hundreds), L2 (tens) and L3 (units) I respectively. Capacitors Cl-C6 are used for noise rejection. A series of three diodes, all lN400l type, have been used for current limiting of the displays and also for maintaining the flow of current in a unidirectional way. Sl resets the counter. Circuit diagram of...
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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