This is different than the standard 555 oscillator circuit in that the LED is placed in the capacitor reset line (pin 7). By doing so, overall current is reduced and the high peak LED current does not flow out of the battery. Since the forward drop of the LED can interfere with the reset threshold voltage when the battery voltage is low, the capac
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itor charge source is via pin 3, the output. In this way, while the capacitor is rapidly resetting via pin 7, it is also being slowly discharged via pin 3 that follows pin 7. That way if the capacitor voltage has a difficult time discharging to the reset voltage (3V or lower), it has a little help via the charge source. Total current drain is in the order of 500uA. A 9V battery can power this for months. 12V is brighter but less convenient because small 12V batteries are uncommon. Each section can stand alone and has an individual reverse polarity diode. You may think that this diode may be eliminated, but destruction is instant if the battery is accidentally connected reverse. This can be assembled either in a strip of (4) or (6) flashers ” all (6) sections are bussed together. Three expresspcb. com miniboards yield a total of 18 (4) position, or 12 (6) position flashers. My prototype has (4) different LED colors, but the BOM lists (6) LED colors. Perhaps you can locate other colors you like better. I actually purchased my LEDs on eBay ”they have some good deals. C1 is 10uF for bright LEDs such as White, Blue and Green ”to help equalize brightness for dimmer LEDs, I simply piggybacked (2) 10uF capacitors to get 20uF. As a group project, students can learn how to identify, handle and solder small SMD devices, and test. The smallest device is the common 0805 size and even I (at my age) can handle this stuff. Smaller sizes...
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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