Create a robotic team mascot for my team at work. My first, humble part of that project was to create a charger for the robot`s batteries. I wanted a battery charger that could charge the various NiMH battery packs that I have, ranging from 700 mAh to 2200 mAh and 1. 2 V to 7. 2 V, and be cheaper than the single-purpose chargers sold at the store. I got some
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general information about battery charging from and more specific ideas for a charger from. The basic idea for my circuit comes largely from that described on the page above, but I omitted the bridge rectifier and filter capacitor, since I`d rather have a reusable external power supply than build the power supply into the charger, and because I expect my power supply to provide DC rather than AC. I replaced the PIC16C711 and crystal oscillator with an ATtiny13A microcontroller. I added switches to control the charge rate and voltage divider, and to tell the microcontroller what kind of battery pack is being charged, and since I didn`t have enough I/O ports available after adding the switches, I used only a single status LED. Finally, I added a 6-pin header for in-system programming. The rate switch sets the maximum charge rate, 0. 4 amps in the slow setting and 1 amp in the fast setting. The charger software will charge at some portion of that maximum rate. The voltage selection switch allows the battery pack voltage to be selected. The charger is designed for 1. 2V, 3. 6V, 6V, and 7. 2V battery packs, but there is some flexibility and these values could be changed in software. The switch is a double pole rotary switch, which allows it to simultaneously inform the microcontroller of the selection and control a voltage divider to halve the voltage from the battery packs over 4V (since the microcontroller`s ADC can only read...
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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