This circuit is used to measure the voltage on a 12V (nominal) lead acid rechargeable battery system. It was specifically designed for use in solar powered systems, but is general enough that it can be used for automotive or other 12V systems. Lead acid batteries normally spend their working lifetime in the voltage range of 11-15 Volts. This meter
Click here to download the full size of the above Circuit.
circuit was designed to show the voltage range of 10-15V on an analog meter movement, it can be used to show the battery charge state from empty to full. The input voltage is filtered from transient voltage spikes via the 10 ohm resistor and the 0. 1uF capacitor on the input of the 78L08 regulator. The 1 Amp series fuse and Transzorb protect the circuitry from short circuits and over-voltage conditions. The 78L08 voltage regulator provides a constant 8V DC supply to the meter circuitry through the 10-15V input voltage range. The dual op-amp is supplied with 0V and 8V for the power rail inputs. The lower op-amp is set up as a buffer stage to provide a 4V virtual ground reference voltage. The virtual ground is used as a current sink for the meter, and as a reference point for the other op-amp. A 78L08 regulator may be a difficult part to find, a good replacement would be an LM317L adjustable regulator circuit set to 8V. Other dual op-amps should work well in this circuit, the 1458 is a good substitution, an ultra-low power dual op-amp can be used if power drain is a consideration. The upper op-amp is configured as a voltage summing circuit with adjustable gain. Gain is controlled by the 100K feedback resistor. The gain control adjusts the meter sensitivity across a voltage range. The measured voltage comes into the upper op-amp`s + input via a 100K/47K voltage divider. The offset control creates a second + input voltage that...
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.....
characters left: