Wiring Diagram

Working principle of this circuit is battery voltage compared with the reference voltage. This circuit is constructed by using 741 op-amp ICs. Op-amp is differential amplifier which output will be positive or negative, depends on the difference of input voltages. When the input voltage difference is positive with respect to reference voltage and battery voltage, then the output is positive and the LED will emit light. If negative LED cannot emit light. It is the main principle of battery level indicator. Voltage level indicated by the column of LEDs. For easy of reading LED rearranged in a vertical array.

The top four LEDs indicates the battery voltage is high. Sequentially the lower level indicates the battery voltage is low and bottom four LEDs indicates very low voltage of the battery. So, if the battery voltage continues to decline then LEDs will die in sequence from top to bottom. In this circuit 1mA current is adjusted for reference voltage. Vcc is divided by the total number of resistor for finding the value of resistor R. On the other hand, the resistor value of R1 is calculated by the equation, Component:

1. Op-amp IC 741

2. R = 3kΩ

3. R1 =220kΩ

4.  Diode

Operation:

The voltage drop against the each resistor is 3 volt.

So when the Vin = 0v or less than 3v the output of all op-amp are at

–Vsat . The silicon diodes protect the light emitting diodes against excessive reverse bias voltage.

When Vin is increased to a value 3v to 6v, only the output of op-amp#1 goes positive  to light which indicate “Very Low”.

When Vin is increased to a value 3v and 6v, the output of op-amp#1 and  op-amp#2  are at +Vsat  and goes positive to light which indicate “Low”.

When Vin is increased to a value 6v and 9v, the output of op-amp#1, op-amp#2 and op-amp#3 are at +Vsat  and goes positive to light which indicate “Medium”.

Similarly, when Vin increased to 12v or higher, the output of all op-amps are at +Vsat  and all op-amps output goes positive to emit light of all LEDs which indicate “Full” .

The schematics circuit of above employs capacitive reactance for limiting the current flow through the LEDs on the application of mains voltage to the circuit. We use only if a series resistor for limiting the current with mains operation. The 100-ohm, 2W resistor series avoids heavy 'inrush' During current transients. MOV at the input prevents surges or spikes, protecting the circuit. The 390-kilo-ohm, ½-watt resistor acts as a bleeder to Provide discharge path for capacitor Cx Pls mains supply is disconnected. The zener diode at the output section prevents excess levels of reverse voltage appearing across the LEDs During the negative half-cycles. During the positive half cycle, the voltage across the LEDs is limited to the zener voltage.

Aseries combination of 16 LEDs Gives a luminance (lux) equivalent of a 12W bulb. But if you have two series combinations of 23 LEDs in parallel (Total 46 LEDs), it Gives equal to a 35W light bulb.

Diode D1 (1N4007) and capacitor C1 act as rectifying and smoothing elements to Provide DC voltages to the row of LEDs. For a 16-LED row, use Cx of 12:22 µF, 630V; C1 of 22 µF, 100V; and zener of 48V, 1W. Similarly, for 46 LEDs combination use Cx of 0:47 mF, 630V; C1 of 33 µF, 150V; and zener of 69V, 1W. This circuit (inclusive of LEDs) costs Rs 200 to Rs 400.

The LED VU meter is simpler and smaller than it's analogue counterpart, and is very common in audio equipment. This version is based on a National Semiconductor IC, and uses the logarithmic version. Each LED operates with a 3dB difference from the previous one, and a jumper is provided to allow dot or bar mode.

The circuit is completely conventional, and is based on the application notes from National Semiconductor. The circuit is shown picture below and as you can see it uses a single IC and a few discrete components. DC to the LEDs is almost unfiltered - C1 is included to make sure the IC does not oscillate, and is not a filter cap. This allows a higher LED current with lower dissipation than would be the case if the DC were fully smoothed, and full smoothing would also require a much larger capacitor. This increases the size and cost of the project - especially important if it is to be used in larger numbers as may be the case with a mixer or analyser.

LED INDICATOR AUDIO AMPLIFIER CIRCUIT SCHEMATIC DIAGRAM

This circuit, connected to the loudspeaker output of an audio amplifier, will indicate the instantaneous output power delivered to the loudspeaker(s) by means of six LEDs illuminating one after another by voltage values increasing little by little, providing the visual impression of a luminous bar or column, increasing and decreasing in height following the increase and decrease of the signal’s level.

Notes:

    * The output power indicated by each LED must be doubled when 4 Ohms loads are driven.
    * The circuit can be adapted to suit less powerful amplifiers by reducing the number of LEDs and related voltage dividers.

Lampu LED Disko Mengikuti Musik

This series consists of 10 led a mounted sequential, Supply 9V IC1A needed to strengthen to 100 times and move the audio signal IC1B. Sensitivity level of the circuit can be adjusted by changing the value of R4. The value of C4 was changed from 220 to 470nF. Each input R9 must be linked with the IC2 output pins.