Low Cost Battery Condition IndicatorCircuit


Posted on Feb 6, 2014

This design combines power-on and low-battery indication, can operate with any battery voltage up to 15V, has very low current drain (2mA or less) and costs less than $3. 50 with new parts. When the battery voltage is above a predetermined minimum, power on is indicated by what appears to be a steadily lit LED. In fact, the LED is being pulsed by a


Low Cost Battery Condition IndicatorCircuit
Click here to download the full size of the above Circuit.

free-running relaxation oscillator formed by IC1c, one gate of a 4093 CMOS quad Schmitt NAND. The frequency of this oscillator should be at least 50Hz, so that it appears to be continuously on while at the same time drawing far less average current than a steadily lit LED. The series resistor for the LED needs to be selected for each battery voltage, to limit the current to a safe vale or you could use a fixed resistor and a series trimpot for flexibility. Low battery voltage is indicated by the LED pulsing at around 1Hz. The battery voltage is monitored by transistor Q1 and trimpot VR1. Once the voltage at its base falls below 0. 6V, Q1 turns off and Q2 turns on to enable the 2-gate oscillator formed by IC1a and IC1b, which runs at 1Hz. The pulses from this oscillator are inverted by IC1d to gate the LED oscillator on and off. Calibration can be done with a variable bench power supply set to the lowest battery voltage you will accept. Power up the circuit and adjust VR1 until the LED pulses once per second. Author: Peter Wilson - Copyright: Silicon Chip




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Butterfly Mixer Circuit
Class A 2A3 audio Amplifier
Car temperature indicator circuit
Electronic crowbar for AC or DC lines
Semiconductor-fail-alarm
A Friendly Charger Schematic for Mobile Phones
Another kind of relay driver board used to utilize your old PC
Specific color sensing circuit
digital to analog
MOSFET-BASED PREAMPLIFIER FOR FM RADIO Project PCB
Motor Turn Stall Detector
Temperature Sensor MAX6698 7-Channel Smart consisting of circuit diagram
High Power Full Bridge Flyback Driver circuit



Top