» Topics » Advice »Modification of the multimeter DSN-VC288 100 volts 10 amperes

Modification of the multimeter DSN-VC288 100 volts 10 amperes

It was inspired by the topic “Connecting a DSN-VC288 voltmeter 100 volts 10 amperes. Everything is simple”, or rather, commenting on it, namely the question of measuring currents greater than 10 A. Here we mean devices without an external shunt. Since “the theory is dry, my friend, and the tree of life turns green” (I don’t remember where), we take a soldering iron and start trying. The task is to increase the upper limit of the measured current to ... Let's think.

The dial gauge has no problems - redrawn the scale and that's it. It is more difficult with a digital device if we increase it by an order of magnitude, i.e. 10 times, then the numbers will match, but the comma will not be in place. If 2, 3, 5 times, then the testimony will have to be multiplied by this number, the correction factor ... Let us skip all these considerations and dwell on expanding the limit to 20 A.

First, get acquainted with the characters.


Above is an old, reliable and calibrated in the factory CLIT ammeter for currents up to 20 A. Below is our hero, DSN-VC288, which, due to the dynamic indication, is unable to photograph all the numbers in any way. I don’t have a normal camera that would compensate for this flicker, so either take a word or ...

First, connect the DSN-VC288 voltammeter (hereinafter referred to as the instrument) in parallel to the standard shunt, we have 75ШСОМ3-50-0.5, give current and see what happened. The device is powered from a separate source.

The reading of 0.59 is at a current of 5 A.



1.19 - at a current of 10 A.
That is, with a 50 amp shunt, the readings changed by about an order of magnitude, although the permissible current due to the shunt should not exceed 55 A. But the shunt is not the most common item in everyday life, let's try a piece of steel wire. The length of the measuring section is selected experimentally.

The device is not yet connected.


Current 5 A, testimony 2.49.



Current 10 A, reading 4.93, unpleasant observation - the wire is well warm, the current cannot be increased, when heated, the electrical conductivity of the shunt changes, an additional error appears. You can, of course, fold the wire two or three times with a corresponding increase in length, there will be no strong heating, but we will go further.

Let's try a shunt from a strip of metal, with the same cross section (and, accordingly, resistance), the strip has a larger cooling surface.
We take the case from Krona.

Everything is clear in the figures.

We mark, cut through.


Solder and turn it on.

Current 5 A, reading 2.39, small, need 2.5.

Current 10 A. The readings of the device, taking into account the correction factor (2), are underestimated, there is little resistance. Cut the strips in width.

And this is what we get.The position of the test wire is selected experimentally.


Everything shows correctly (coefficient!), But a lot of voltage drops on too thin Chinese wires. We change them to more suitable ones.




Wow, where I had to move the test lead (red from the instrument). If you now solder red thick there, then the extra piece of the shunt (3/4) can be cut off.

More current and maximum.


Still, this shunt is warm, it was necessary to cut the strip wider and longer.
Thus, at a current of 5 A, the device shows 2.5, at 10 A - 5 and at 20 A - 10. I believe that by this method it is possible to produce a shunt for any current within a reasonable range.
But nevertheless, a more radical way would be more correct - to remove the native shunt from the board and put an external home-made shunt (the standard is hardly suitable).

Removing the shunt from the board.

Something like this. The native shunt is sealed here, as an example.

Everything, comment.

Suitable for topic

Related topics

Add a comment

    • smilesmilesxaxaokdontknowyahoonea
      bossscratchfoolyesyes-yesaggressivesecret
      sorrydancedance2dance3pardonhelpdrinks
      stopfriendsgoodgoodgoodwhistleswoontongue
      smokeclappingcraydeclarederisivedon-t_mentiondownload
      heatirefullaugh1mdameetingmoskingnegative
      not_ipopcornpunishreadscarescaressearch
      tauntthank_youthisto_clueumnikacuteagree
      badbeeeblack_eyeblum3blushboastboredom
      censoredpleasantrysecret2threatenvictoryyusun_bespectacled
      shokrespektlolprevedwelcomekrutoyya_za
      ya_dobryihelperne_huliganne_othodifludbanclose
5 comments
Listen, I like you only when I read the article to the end. No offense.

When you started these experiments with steel wire and its heating, I immediately fell ill. I know (and you know !!!) what materials shunts are made of and why.

But when you remembered that the wires from the Chinese multimeter are frail in cross section, I felt better. And when the thought came to replace the regular shunt of this device with another, then I was completely released xaxa boss

Do not be angry with me, I know that you are a pro, it just took you to the wrong steppe.

P. S. I wonder what accuracy class the switchman has, what is in the photographs? I enlarged, reviewed all the pictures, did not understand what is on the scale.
Author
Quote: Korolev
Eh, well, what prevented you from taking measurements with a soldered shunt and a standard shunt connected instead?

Laziness
Eh, well, what prevented you from taking measurements with a soldered shunt and a standard shunt connected instead? And yes, actually shunts are made, as a rule, from manganin.
Author
Damn, like the guy said nothing offensive, but hooked ...
In order.
......
Nobody advises anyone, their actions are described.
.......
Oh how! And why in vain, it’s in kind.
......
And with a DSN-VC288 measuring device will work? Haha three times. About the nonlinearity of the scale ... Read on the relevant forums.
......
What am I talking about? Do not allow heat. Alas, I don’t have Konstantan and Fehral.
dimmich
You would open the topic to the end before advising reading novices to repeat your actions. After all, they will read it and believe it. But in vain. It is impossible to use tin and steel wire as a shunt! With such a shunt, the measuring device will not work. Nonsense will work out.

Different current will flow through the iron "shunt", respectively, different heating, and its resistance at different temperatures will vary significantly. And the readings at different temperatures of the shunt will be different.

Think a small margin of error? What a big one. I myself have tested various materials, including iron. Well, it doesn’t suit you as a shunt! The current readings on the device float strongly.

We advise you to read:

Hand it for the smartphone ...