3 led Level Audio amplifier Indicator

This circuit ican be used to show the power output level of any audio amplifier. The circuit is very simple and displays three power levels that can be set to any desired value. For a standard HiFi stereo power amplifier like the 25W MOSFET Audio Amplifier.

Skema Rangkaian 3 led Level Audio amplifier Indicator

Component List Of 3 led Level Audio amplifier Indicator

R1.................. 100K   1/4W Resistor
R2.................. 50K   1/2W Trimmer Cermet
R3.................. 330K   1/4W Resistor
R4.................. 1M2  1/4W Resistor
R5.................. 470K   1/4W Resistor
R6,R7............. 500K   1/2W Trimmers Cermet
R8.................. 1K5  1/4W Resistor
R9-R11............ 470R   1/4W Resistors
C1.................. 47pF  63V Ceramic Capacitor
C2.................. 100nF  63V Polyester Capacitor
C3.................. 47µF  25V Electrolytic Capacitor
C4.................. 1µF  25V Electrolytic Capacitor
D1.................. BZX79C5V1 5.1V 500mW Zener Diode
D2.................. 1N4148  75V 150mA Diode
D3-D5.............3mm.  Yellow LEDs
IC1.................. LM339  Quad Voltage Comparator IC
SW1.................. SPST  Slider Switch
B1.................. 9V

Other settings are possible IC1A is the input buffer, feeding 3 voltage comparators and LEDs drivers by means of a variable dc voltage obtained by R5 and C4 smoothing action. In order to achieve stability settings, the supply of IC1 and trimmers R6 & R7 is reduced and clamped to 5.1V by Zener diode D1.


About IC LM339

The LM139 series consists of four independent precision voltage comparators with an offset voltage specification as low as 2 mV max for all four comparators. These were designed specifically to operate from a single power supply over a wide range of voltages. Operation from split power supplies is also possible and the low power supply current drain is independent of the magnitude of the power supply voltage. These comparators also have a unique characteristic in that the input common-mode voltage range includes ground, even though operated from a single power supply voltage.

Application areas include limit comparators, simple analog to digital converters; pulse, squarewave and time delay generators; wide range VCO; MOS clock timers; multivibrators and high voltage digital logic gates. The LM139 series was designed to directly interface with TTL and CMOS. When operated from both plus and minus power supplies, they will directly interface with MOS logic- where the low power drain of the LM339 is a distinct advantage over standard comparators.

IC LM339 Applications

• High precision comparators
• Reduced VOS drift over temperature
• Eliminates need for dual supplies
• Allows sensing near GND
• Compatible with all forms of logic
• Power drain suitable for battery operation.