This circuit was designed as a warning flasher to alert road users to dangerous situations in the dark. Alternatively, it can act as a bicycle light (subject to traffic regulations and legislation). White LEDs only are recommended if the circuit is used as a bicycle front light (i. e. for road illumination) and red LEDs only when used as a tail lig
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ht. During the day, the two 1. 6-V solar cells charge the two AA batteries. In darkness, the solar cell voltage disappears and the batteries automatically power the circuit. The flash frequency is about one per second and the LED on-time is about 330 ms. The duty cycle should enable the batteries to power the circuit over night. The circuit is composed of three parts. Under normal daylight conditions the batteries are charged through diode D4. In darkness, pnp transistor T1 is switched on, supplying battery current to the second part, a low-frequency oscillator comprising T2 and T3. The third part is the LED driver around T4. It conducts and switches on the LEDs D1-D2-D3 when the collector voltage of T3 swings high. Two LEDs (D1, D2) are 20, 000-30, 000 mcd high-brightness yellow types and one (D3) is a normal 3-mm red LED for control purposes. Of course it is possible to increase the number of LEDs to obtain higher brightness. However you will run into limitations regarding the maximum collector current of transistor T4. For really high power applications a MOSFET transistor is suggested instead of the common or garden BC547B.
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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