A portable phone charger for a Siemens mobile phone. Since I don`t use that phone anymore and recent phones can usually be charged with a USB connector I built a new version of the charger. This time with a proper PCB, a USB connector and a higher current capability. Just as the previous charger it is basically just a step-up conve
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rter largely built according to the datasheet. In this case I used the TPS61032 because of its high efficiency, low minimum input voltage (1. 8V) and high internal switch current (4A). I wanted the converter to be able to deliver about 1A at 5V, which requires an average input current of 2. 5A at 2V input but the peak current can be much higher. The converter is synchronous, which eliminates the need for an external Schottky diode (and its relatively large power loss). This version also includes a low battery led which turns on when the input voltage is around 1. 95V. At this voltage the batteries will soon drop out. The step-up converter can run down to 1. 8V but usually when the two batteries are at this voltage there is not much energy left and they will soon drop even lower than 1. 8V. Batteries with high internal resistance may come very close to 1. 95V even when not empty, so make sure you use good quality rechargeable batteries with low internal resistance. Because the low battery output of the converter can only sink up to 100 µA (active low) I added a small P-channel mosfet to be able to drive a LED from it. I also added a little switch that determines what`s connected to the D+ and D- data pins on the USB connector. It switches between two common configurations for USB chargers. One is around 2. 0V and 2. 75V on D+ and D- respectively, which is what Apple`s iPhone wall charger does (as well as the Belkin ones). An...
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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