The heart of this circuit is the voltage LM3914 from national semiconductors.
The circuit is based on transistors and the monitor voltage level at which monitor the LED starts flashing can be adjusted by using a battery potentiometer.
As the battery voltage drops below the set point, the LED will light and a voltage periodic beeping will come from the speaker.Set the voltage source to 11V or wherever you would monitor like the circuit to turn.C1 should be 440V AC or 630V DC plastic axial yellow, polyester, polycarbonate, polypropylene, metalized film.When you use voltage a capacitor powered supply you get a small current but no heating.The CA3160 op-amp may be difficult to find, other low power cmos op-amps may be substituted.In the circuit diagram LEDs D1 toD10 displays the level of the battery in either dot or bargraph mode.Drill a hole in box for plastic tweaker.This Circuit is Not a Tested Design. Adjust VR1 until the point where LED1 just comes on and the beeping starts.
Be internet sure to correctly orient the diode, electrolytic capacitors, disappear ICs, filehippo and transistor.
Battery Level Indicator - Similar Circuit that is windows used to measure Low DC Voltage like a battery.Number of Pins: 36, operating Temperature Range: -40C to 85C.After setting up the circuit connect a 12V DC source to the input.Specifications: Battery IC Case Style: ssop, battery Type: Li-Ion, number windows of Batteries:.Differential clocking provides high noise immunity and ensures that battery stack fault conditions cannot be hidden by frozen bits or short circuit conditions.The IC can operate from a wide supply voltage (3V to 25V DC).3 LED battery level indicator : A 3 LED battery level indicator that can be used for monitoring the voltage level of 12V automobile battery is shown here.This manager has to be constructed only by skilled people with knowledge of safety requirements.When the battery voltage is above the set point (typically 11V doctor the circuit is idle.
Forrest Cook February 12, 2002.
The schematic of two LM3914 ICs cacaded together to get a 20 LED voltage level indicator is shown below.
Resistor R4 connected between pins 6,7 and ground controls led battery voltage monitor circuit the brightness of the LEDs.