A bicycle light control circuit which reads in various buttons and sets various outputs accordingly such as headlight, taillight, blinkers, etc. My current design is based around an ATtiny24 ( Datasheet ) using the internal oscillator (8MHz), programmed in C using AVR-GCC. I would like to keep external components such as shift registers to a minimum. Resistors are OK since they are cheap and small, and I am using
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MOSFETs (NTD4960N: Datasheet ) to drive the LED banks. Essentially, what I am looking to do is drive the MOSFETs with a 200Hz PWM signal to control the LED brightness, but limit the duty cycle to 90%. With that in mind, I would only need a pin to be an output for a maximum of 90% of the time. In the remaining 10% of the time, I want to switch the pin to an input to read the state of a button. I tried a lot of various configurations to allow the MOSFET to stay OFF when it is supposed to be OFF, regardless of input from the button, and this is the best I could come up with: The supply voltage (VCC) is 5V, so when the button is pressed, about 0. 9V is seen at the transistor gate. This is not enough for the transistor to start conducting, but it can be read by the MCU ADC which has been enabled using the internal 1. 1V reference. So the code drives the MOSFET with a 200Hz PWM signal. The duty cycle will vary with the desired LED brightness, but will not be greater than 90%. During the last 10% of the PWM cycle, the I/O pins are set as inputs (internal pullups disabled, digital input buffers disabled) and the ADC is used to read the state of the pin. The 10k resistor keeps the MOSFET off, and if a button is pressed, 0. 9V is read by the ADC. This value is still not high enough to turn the MOSFET on, so the LEDs stay off, regardless of the button press. Since the ADC is turned off and on, I discard the first reading and keep the...
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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