BATTERY LOW INDICATOR 12V

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General purpose 12 volt battery low indicator, wired around IC 741 is presented here.You can add this little circuit in your electronic inverter,emergency back up light,computer ups unit etc.The red LED(D2) lights up when the battery voltage level drops beyond the set value.An active piezo sounder can also be used in place of D2.Note that adjustment of preset pot P1 is very critical in this design.

(circuit reproduced from circuit library of betron teklabs - some rights reserved)

BATTERY LEVEL INDICATOR 12V

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Here,in this simple and economic design,one popular quad voltage comparatorLM339(IC1) is used as a simple LED meter to indicate the health condition of a 12 volt, lead acid battery. A steady 5 volt reference voltage,generated using components R6 and ZD1, is connected to each of the (+) inputs of the four comparators and the (-) inputs are connected to successive points along a voltage divider. The LEDs will illuminate when the voltage at the negative (-) input exceeds the reference voltage.

Calibration(one time) can be done by adjusting the potentiometer(P1) so that all four LEDs illuminate(100%indication) when the battery voltage is at near 12.7 volts, with zero load on the battery.

(design reproduced from circuit library of betron teklabs-some rights reserved)

HIGH POWER SEARCH LIGHT

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Circuit presented here is that of a high power search light using nine ultra bright white LEDs.At the heart of the circuit is one adjustable voltage regulator IC LM 2941.Recommended input voltage for this circuit is 12 volt dc,preferably from a rechargeable SMF battery.With the help of variable resistor R2,user can dim or bright the light output.

BULB SAVER CIRCUIT

Proven design of an electric bulb life extender is reproduced here .You can easily construct this little circuit using generally available electronic components.First of all,make your own PCB using the layout guidance given above.Next assemble the circuit and enclose it in a proper plastic box.Note that the PCB layout is not in actual size!

Input:AC 230V supply
Output:AC 230V Bulb(100W max)
D1,D2 = 1N4007 Silicon diodes .
R1 =10Ω 5W wire wound resistor.
R2 =4Ω7 NTC resistor.
C1 = 1uF/630VAC polyster capacitor.

USB POWERED PC SPEAKERS

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Here is an easy to assemble circuit for PC multimedia speaker.The circuit works off a 5 volt dc supply.It consumes little current,so dc supply output(5v) from a usb port can safely power the circuit.Take any general purpose pcb and cut it into a small size.Thereafter,assemble the circuit and enclose it in a suitable cabinet.At the heart of the circuit is IC:TDA 7053A.
(circuit designed by t.k.hareendran & re-tested at betron digital labs © rights reserved)