The phone is a Siemens S65. The official charger that came with the phone says 5V at 420mA. Because these things do not always actually deliver what is printed on them I measured the voltage myself. This is actually quite hard with the tiny contacts on the connector, especially when it also has to be plugged into the phone. Without a phone connected the voltage
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was much higher, around 8V if I remember correctly. When the phone was actually connected the voltage would drop to around 4V and even lower. The label says output: `5V-11V DC 350mA`. Of course I opened this thing to look what was inside. I found a cheap looking PCB with a step-down converter based on Motorola`s well known MC34063. Based on the component values it was configured for a 8. 75V output and a current limit of 320mA. When connected to the phone the voltage drops below 5V because the current limit is reached. To see at what voltage the phone starts charging I cut off the connector from the car charger and put 5V on it. The phone did not started charging. At 5. 5V still nothing, but at 6V it started charging. As was shown with both the official charger and the cheap car charger, once the phone starts charging the voltage may get well below 5V without problems. But it needs around 6V to get started. To get 6V out of two AA batteries I used a LT1949 switching step-up converter from Linear Technology. An AA battery typically delivers about 1. 2V-1. 5V but the voltage drops even lower under load and as they discharge. The LT1949 already runs at a voltage of 1. 5V so two AA batteries are enough to keep it running, even at low battery voltages. The IC has an internal switch current limit of about 1. 1A. This will limit the output current. In fact, the phone tries to use so much current that the current limit kicks in and...
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....
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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....
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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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