I need a portable diy electronic AC volt meter, to avoid transportation of Scopes. - diyAudio
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Old 21st August 2005, 09:28 AM   #1
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Default I need a portable diy electronic AC volt meter, to avoid transportation of Scopes.

Can you help me please?

My need is an average or peak, or even peak to peak metering system to output voltage, over speaker loads or dummy loads.

The problem with standard meters, are that they need a sinusoidal and fixed voltage, and frequency range width is too small, needing 60 hertz continuous signal to have some precision.

I had, many times, to go to friend's houses carrying Wave form Monitors.

I need a transistorized circuit, not an op amp circuit or even a chip amplifier....my preference is a discrete transistorized circuit, operated from batteries that can read with a reasonable precision (under 5 percent) with a more extended frequency range than the standard analog or digital multimeters (the cheap ones)....not needed the capacity to have all audio spectrum precision, but that capacity can be very interesting too... a flat amplifier aid can be very nice.

Those ones that you can calibrate by yourself, using some reference..some well known reference, the ones you can adjust, the ones you can use a S-Meter or even a VU meter, using it's own scale as reference to construct our RMS scale making some convertions, some calculations and some art work to produce panels.

I had one that made a reasonable work, a Fluke 87 Multimeter, now the good friend (that fluke) is dead .... so i need to construct something to mobile measurements...remote measurements... something portable to outside home work.

Do you have a sketch, a diagram, a schematic, or something to help me.

Post it here, or, if you prefer, go direct to my mail.

nanabrother@yahoo.com

thanks in advance.

regards,

Carlos
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Old 21st August 2005, 01:24 PM   #2
anatech is offline anatech  Canada
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Hi Carlos,
Yup, that Fluke was good to what, 200KHz on AC? Any of the old AC meters would rectify the AC so that the response of the amplifier and detector were the limiting factors. Look at the Leader LAV191 schematic, or the older HP AC meters for audio. The meter movement is only important for DC accuracy at this point.
Alternatively, some of the newer true RMS converter chips preceeded by a buffer / amplifier circuit (could be discrete) would give you a very accurate insturment. Add a digital display for steady state signals, again you only need DC accuracy. 3 1/2 digit basic meter kit is a cheap way to do this.

BTW, how on earth did you kill the Fluke? They are pretty tough, and have lot's of internal protection. They might even survive if you run over them in a truck (seen that).

-Chris
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Old 21st August 2005, 03:27 PM   #3
mzzj is offline mzzj  Finland
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How about watt-meter?


Bob Pease had article somewhere at national website.
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Old 21st August 2005, 03:37 PM   #4
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Wonder why you wouldn't want an op-amp based circuit. This is a voltmeter you want, not a hi-fi guru amplifier....

I highly doubt you can make something better by not using op-amps.
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Old 21st August 2005, 03:44 PM   #5
anatech is offline anatech  Canada
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Hi Carlos,
I just sent you a bout 3Meg PDF for something that might work for you.

Let me know if you get it.

-Chris
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Old 21st August 2005, 04:36 PM   #6
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Default There are Destroyer guys that can do those things Anatech.

They are almost impossible to destruct, but they did not knew me before they told that.

The Multimeter was shutting down by itself...first defect.... display had problems....one side darker than the other, and a friend asked me the Multimeter to use for a week...hehe...he did not told me that the hi ampere scale had the fuse blew....and having not another one, the "idiotic" friend replace the fuse with a heavy gauge jumper wire...and he forgot to remove the jumper, replace the fuse or inform me when he return the equipment to my home.

The second idiot, me..... destroyer X...the extra Destroyer, receive the instrument and many weeks latter, this last week i made a short in my supply output, to see its short circuit current capability...a small supply.... it shows me 13.4 amperes...... as turning of automatically all the time, i forgot to remove the leads from the high ampere plug.... and last week i plug it in a decided and fast way, direct into the 220 mains outlet...it explode inside and melted some part in my hand... the rubber protection smelling a lot.

I told nothing to my friend Paulinho... a very good guy.... will not disturb him.... as i crashed his car last year, and he did not accepted a dollar...his repair costs reached 500 bucks....so...deal made.ahahahahah!

Anatech, thank you related the file you will send me.

.................................................. .................................................. ...
MZZJ, yes, this is the one i need...having more detailed informs, i will thank you very much, and will sent you some brazilian warm to melt some ice from your neighborhood.

.................................................. .................................................. ..
Audio Wizard... escuses moi,monsieur, bonjour pour vous.

I am sorry Mr, a good day for you.

Each one of us have our dark side, some pre conceived dirty ideas.... for instance, i do not apreciate womans under 30 years old, as they are not experienced, and this is not some idiotic idea...this one is my clever side.

But i have many stupid ideas too, i do not like op amplifiers and also i hate chips....i do not apreciate things that i cannot see...those black boxes, and many of them we cannot find the internal circuits to observe and evaluate.... do not like secrets..i prefer discrete components.... those things hard to understand...i must confess you that i also have some troubles to understand me.

Also i love audio...and those op amps do not have a good audio swing capabilities, limited they are because of supply voltage..this is something terrible.... so old they are, and have this problem now a days, they do not have internal supply regulation to let us free of those limiting factors.

Related audio chips, normally, they have internal small distance from input to output...this means to me that it can oscilate, and to avoid that oscilations, there are many capacitors that destroy all the audio quality...aaagh!...i do not like them.

regards,

Carlos
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Old 21st August 2005, 04:45 PM   #7
anatech is offline anatech  Canada
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Hi Carlos,
Okay, that's a good way to end a great meter! I've seen others do the same thing before. B.E.R. Beyond Economical Repair. Sad. If you can afford it later, it's about the best all around meter to have.

I am sure you can modify the circuit I sent you for your purpose. Let me know when you are done how it worked out for you.

You know Carlos, when we get older, we want a calm woman. Too much drama, false excitment, with the young ones. I understand you there!

-Chris
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Old 21st August 2005, 05:03 PM   #8
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Default You get it...hundred percent, this one is more than i hope for

This circuit is perfect to me.... perfect!

Those "Made in USA" are lovely things.... i miss very much those old days, when Made in USA was a reason of pride.

Now they are buying Japanese cars!...nothing against Japanese cars...but were's those lovely V8?.....can make them with reduced consumption too, smaller sized motors, and smaller cars too.

I think the more old Japanese guys may be laughing and thinking:

- "You have sent me a bomb around 1945, my revenge is that i will transform your pride, your cars will be alike "bombs", and i will invade you in a peacefully way... kicking and smilling"

I was in Los Angeles in 1982.... i turn myself redish, furious!... my desire was start to scream:

- How could American guys do that with your their Industrie?

All i coud see was Hiunday, Subaru, Mazda,Toyota,Honda... and i was driving a rented Thunderbird...Yeah!...protecting America...you do not know the finger i was controling not to show to everyone driving a Japanese car.

And them i drive the enormous Thunderbird..hehe...white leather seats.... wonderfull engine sound...better than music... i was visiting beverly hills when i saw wood used to construction.... and wrote over the wood "Wood from Amazon".... do you know some thing the dogs do near a three?.... Yeah!...i made it in the nearest three!...facing Hollywood inscription and with extreme internal revolution.... intervenctions were made to protect Amazon Jungle... and that forbiden wood entering Beverly hills.....Aaaaaaagh!

Returning to Los Angeles, i rented a Japanese car.... and i start to smile to the ones that are using Japanese car... remembering my dog's revenge!

We are still protecting big cars...Mopars wonderfull machines from USA... those, you can see, was made here... from the first screw to the last wire... we go using them, powered with nature gaz... we have Japanese cars beeing constructed here... they are better and cheaper..but we go buying the ones that arrived here in the fifties...GM, Volkswagen, Ford and others.... defending the good things...Yeahhhh!

All rigth....you also experienced with girls my friend...you are rigth.... not fake screams ...ahahaha..you got it!

regards,

Carlos
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Old 21st August 2005, 05:29 PM   #9
anatech is offline anatech  Canada
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Hi Carlos,
Well, they all voted with their dollars! Gottcha!

I have a nice V8 (5.7L) in the driveway too. Roadmaster wagon. Rumbles nicely and the young guys don't understand until they can't catch the tailgate. And that's with my wife driving!

Poor old thing needs work.

-Chris
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Old 21st August 2005, 05:36 PM   #10
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Default Oh! My God!... 5.7 litters!!!... can you please make audio recording

hehe...near the exaust.....with a good microphone, or even some electred damn thing.

Make it and sent me.... idle and acelerating...this is music to me.

M_U_S_I_C to me!!!!

Yeah!... 10M of audio...make lower than 10M in MP3, because it inflates when transmitted...sample it over 32K please...and send big Charlie...i will very happy with that music.

Having a picture send too..... i envy you..... i can see in front of my building one Eldorado, a Cadillac...not rust.... color of red grapes.... the one did not accepted 2K i offered him.... every saturday i hear the music of the motor running...he use to run it for 3 minutes and only next week to hear that show again.

The schematic you send, the whole manual, was great Anatech..thank you very much...i am satisfied, and i have any other one need in that thread...only to talk alike parrot till moderator kick us to outside earth!

regards,

Carlos
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