This circuit is designed to check the condition of lead-acid and gel cell batteries with capacities greater than 20Ah. It switches a load of about 18A at a rate close to 50Hz so that the internal resistance of the battery can be measured using a digital multimeter across the battery terminals. The measured AC voltage in millivolts divided by 10 (i
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e, a shift of the decimal point) is approximately equal to the battery`s internal resistance in milliohms. As shown, the circuit is quite straightforward and is based on two 555 timer ICs (IC1 & IC2) and power Mosfet Q1. IC1 operates as a monostable timer with a period of 10s. When switch S1 (Test) is pressed, IC1`s pin 3 output goes high for 10s and this enables IC2 which operates as a 50Hz astable oscillator. IC2 in turn drives power Mosfet Q1 which is connected across the load in series with three 0. 22W 50W resistors. IC2 then turns off again after 10s - ie, at the end of the monostable timing period. LED1 provides power indication when the circuit is connected to a battery, while LED2 (green) comes on during the test period. The thermostat is not necessary unless the unit is to be used repeatedly (the Jaycar ST-3823 70 °C unit is suitable) and you want to protect the output circuit against overheating. The power Mosfet does not need cooling but the thermostat and the 0. 22W 50W resistors should all be mounted on an aluminium heatsink at least 2mm thick. In practice, the internal resistance of car batteries can vary from about 15mW down to about 3mW. Before testing the battery, check that the electrolyte level is correct and that the voltage across its posts exceeds 12. 5V for a nominal 12V battery; ie, close to full charge. That done, switch on the car`s headlights and measure the DC voltage between each battery post...
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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