These were about $60 a pair with charger and batteries, and have a three-bar battery gauge. With experimentation I found that if the voltage is greater than 4. 28V, all three bars light up. More than 3. 47V, two bars will light up. Below this latter voltage the radio chirps regularly, and only one bar will light up. After a few years use, we noticed
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the batteries do not last longer than a few hours, so I wanted to replace them. A search on the web shows that the battery packs are about $12 each (plus shipping), and their capacity is still only 600mAh, so I decided to investigate a home-brew battery replacement for these units. I pealed back the sticker on one battery pack and discovered that the hidden elecronics are very simple and can be easily reproduced. One terminal of the charger connections connects to the negative terminal of the battery pack, and the other terminal connects to the positive terminal via a blocking diode. Insert the three batteries into the radio, and verify that it powers up. If it doesn`t you may have to bend the metal tabs out to meet the battery terminals. Remove the paper backing, on the tape, and fold the tab over so that the tape forms a `b` shape. The top arm of the `b` is not sticky on either side because you folded the tab over. The bottom belly of the `b` is sticky. Tape the bottom (belly) part of the `b` onto a corner of the paper substrate (top copper tab in the pictures below). Have the non-sticky top arm stick out of the edge. Insert the top arm of the `b` under the negative terminal of the battery. Since you folded the tab under, both sides of this leg are exposed copper and will make good contact with the battery and the radio terminal. Tape the 0. 75" square piece of copper tape in the opposite corner of the paper (see below)....
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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