Skip to main content

3 Level Audio Power Indicator Circuits Diagram


This circuit is designed to indicate the power level output of any audio amplifier. It's simple, portable, and displays three power levels can be adjusted to any desired value.


 3 Level Audio Power Indicator Circuits Diagram


3 Level Audio Power Indicator Circuits Diagram

Parts:
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  PP3
 
Clip for 9V PP3 Battery
 
 

Circuit operation:

This circuit is intended to indicate the power output level of any audio amplifier. It is simple, portable, and displays three power levels that can be set to any desired value. For a standard HiFi stereo power amplifier like the 25W  Audio Amplifier described in these pages, the power output values suggested are as follows:
  • D5 illuminates at 2W
  • D4 illuminates at 12.5W
  • D3 illuminates at 24.5W
The above values were chosen for easy setup, but other settings are possible.
IC1A is the input buffer, feeding 3 voltage comparators and LEDsdrivers by means of a variable dc voltage obtained by R5 and C4 smoothing action. In order to achieve setting stability, the supply of IC1 and trimmers R6 & R7 is reduced and clamped to 5.1V by Zener diode D1.

Notes:

  • The simplest way to connect this circuit to the amplifier output is to use a twisted pair cable terminated with two insulated crocodile clips.
  • Setup is best accomplished with an oscilloscope or an audio millivoltmeter like the one described in these pages. Precision Audio Millivoltmeter
  • A 1KHz sine wave generator with variable output is also required (see a suitable circuit in this website also). 1KHz Sinewave Generator
  • Connect the generator to the amplifier's input and the Audio Power Indicator to the output of the amplifier, in parallel with the oscilloscope probe or the audio millivoltmeter input.
  • When using high power outputs disconnect the loudspeakers to avoid Tweeters damage and connect in their place an 8 Ohm 20-30 Watt wirewound resistor.
  • Remember that VRMS output is equal to output Peak-to-Peak Voltage divided by 2.828.
  • RMS power output in Watts is equal to VRMS2 divided by speaker impedance (usually 8 or 4 Ohm).
  • Example: set the output of the 1KHz sinewave generator to read 14V on the audio millivoltmeter (24.5W @ 8 Ohm). Set R2 until D3 illuminates, and be sure that D3 turns-off when diminishing a little the generator's output.
  • Do the same with R7 for D4 and R6 for D5. The readings of the audio millivoltmeter must be 10V (12.5W @ 8 Ohm) and 4V (2W @ 8 Ohm) respectively.

Labels:

Comments

Post a Comment

Popular posts from this blog

A basic Arduino Solar PV Monitor

I have just recently had solar pv installed, mainly to future proof my energy costs, I do not expect it to be like drilling for oil in my back garden, however the return looks to be encouraging. The install gives you another single unit meter, from this you will see the total amount the panels produce, but that is about it. I wanted to know how much the production was as it was happening, I discovered the light blinks on the front of the meter will flash 1000 times for each kWh of electricity which passes through. The rate of the flashing of the LED tells you how much power is currently passing through the meter. [ ]
Post a Comment
Read more

Build a Key Operated Gate Locking System Circuit

This simple key-operated gate locking system allows only those persons who know the preset code to open the gate. The code is to be entered from the keypad within the preset time to operate the motor fitted in the gate. If anyone trying to open the gate presses a wrong key in the keypad, the system is disabled and, at the same time, sounds an alarm to alert you of an unauthorized entry. Figs 1 and 2 show the block and circuit diagrams of the key-operated code locking system, respectively. Connect points A, B, C, D, E, F and ground of the circuit to the respective points of the keypad. Keys S7, S16, S14 and S3 are used here for code entry, and the remaining keys are used for disabling the system. It is very important to press the keys in that order to form the code. To start the motor of the gate, press switches S7, S16, S14 and S3 sequentially. If the keys are pressed in a different order from the preset order, the system will lock automatically and the motor will not start. Fig. 1: Bl...
Post a Comment
Read more

Apple releases TV spot for new iPods

Apple has just released a fun commercial to showcase its new line of iPod players and the various colours they come in. The TV spot titled ‘Bounce’, has a bunch of colourful iPod touch, iPod nano and iPod shuffles er…bouncing to music. With all that colour and dancing and bouncing, you may forget that Apple’s latest gen line of iPods has some other awesome features. For instance, the fifth gen iPod touch comes with Siri, 4-inch retina display and an A5 chipset. Maybe the next ad will showcase some of these features with less bouncing.link
Post a Comment
Read more