Dx Led Wattmeter, it can be usefull, and you can modifie and put your name on it

I do not mind those things.

I have nothing, nobody have nothing, we are passengers in this life, in this planet...eveybody we have are borrowed by the destiny or result of you effort in expend you life time working for money.... you will not travell the long and no return journey with this money...so...be happy... enjoy this life...as the other will be different.

If you like this one, the circuit!.... i will be happy if unless one guy use it..and can be done with a single led, to a single power indication.

I will assemble it soon....i am sure it will work...too much simple not to work.




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I made it to use with my Symassym subwoofer power, and will be switched to others .

This is a Dx developed Wattmeter with Leds.

Circuit is very simple, the 47 ohms resistors are there (at least one of them) to avoid to load the amplifier output circuit.... an 8 ohms resistor shown is the speaker.

The circuit rectifies the audio wave, in special low frequency will be measured as we jump into a filtering...and that 2,2uF or even 3.3uF seems to be enormous related the consumption it will face.... this will filter hi frequencies rectified and will produce a delay to “erase” the leads.

I did not assemble it yet.... was made using Simulator, so the timing will need adjustments, and will be done changing this electrolitic condenser value.

The audio rectified and filter will enter a resistance voltage divider, and the lower resistance is always 2K2.... the voltage divider will decide the amount of voltage that will let 0,65 Volts from base to emitter, and this will turn the transistor on.

The colector to emitter is connected in series with 330 ohms to work as limiting resistor, and i suppose will need some adjustment too, to have the brigth you want, and in series you have the Red ligth emitting diode.

The colector circuit is feed by a 12 volts supply...and this voltage do not need to be exactly 12 volts...you can reduce a little or increase it a little, but as you see, the circuit is simple and the base to emitter consumption is small, producing a good time to the leds ligh off, having time enought to you to read, to think about and evaluate what is your average power.

The power measured is around (not precise); 5, 15, 20. 30, 45, 60...but installing more two stages, one using 82K and the last one 110K to base, you will have more two interesting power measurements; 85 and 110 Watts....over 8 ohms...if you use 4 ohms loads..... all those watt numbers suggested, and with not more than 10 percent of errors, will result doubled.

No, i did not constructed yet...but i am sure it will work, because it is incredible simple...a real diy product, and i made using my own ideas and i copied nothing...every similarities, i ensure you, hundred percent result of coincidence....accident....or some “ Universal interconected minds”.

But really guys...if you like it...put you name over it and be happy, as i will be too.




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Oh friends!...i am sorry, this circuit is a bull ship!... awfull...slow, very bad.

With continuous sinusoidal waves it measure reasonable.... but with music...too much slow... the condenser charge time slow down the circuit too much, and without it, voltage is reduced because not rectified.

The way it is now...no chance..only if some real designer decide to took care of it.

I will thank everyone that help me and enter decided to cooperate.

Damn reality... the deep frustration....i am feeling alike a looser.... but i will be better, i will be happy again in a matter of minutes... as that "thing" is mine...i can explode the whole thing!

Do not tell other guys....hehe...."I will shot this damn thing"...better to shot it than continue to face the terrible reality.

I reduced the resistors and capacitor...but not good for audio.... no good..do not construct that trash the way it is now!

Yes!..i will try to inject the audio directly.... with a small load and inject directly into input.... removing rectifiers... will try!


I made small modifications to maintain the same brigthness to all Leds, and others

Small modifications.... to steady tone, it is precise..but with music, it measure lower than real, the electrolitic and rectifier are slowering down... circuit not fast enougth to follow peaks, and high frequencies measurements are attenuated.

Good for bass measurements...i am using rigth now.

I do not think this is a good circuit.... a good trash this one...but, beeing the only one i have, will use it till another thing better appear using discrete components.




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I really made it...not a simulation...this "thing" is working...but not the way

I was dreaming of.... i was interested in fast response to rise time...and slow decay...some retaining ligth for half a second...to go off slowly.

No good...and nobody helped me...oh my God!..no one likes those flashing things!...oh life!...oh day!...oh bad luck!




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Yes, i put it to work, was tested..and the ligths goes flashing

But musical response was not adequate...60 watts peaks were not followed by ligth.

Was slow...measuring less than real...so...i change all resistors i could...and now it is measuring very well...but with music...if i install a continuous tone...oh God!.... even with 10 watts...all LEDs will be ON!




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What can i do...no one came to help me...no one!

This is terrible...what a loneliness....forum guys really do not like those flashing things...may be something strange...too much ridiculous maybe....yeah...alike those cars that dance!...

I understand...here we call Cafôna.... those woman that put too much lipstick...more than the mouth perimeter...use enormous hat and use strange collors...talk too much loud, having no education...i understood.

Oh God!... am i cafôna?




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Hi! Carlos

Few years back here in India we used to get complete LED VU meters using only transistors. I never bothered to trace them but they worked fine. All I remember, each of the devices was connected one after another.

A Google has bought this up ignore the input and tailor rest to your liking.