Welding Pulse Monitor

I haven't ever seen real welding wave forms either in direct current welding for steel sheets or alternative current for aluminium, magnesium.
if I was able to see them it should be informative in determining several important setting values.

So I tried to set up a current detector added to my welder, by applying a hall effect sensor unit being sold on the market, at around the ground cable of my old analogue welder.

Attachment 35933

Red curves with arrows tell how welding current goes while the arc melts metal, it might sound funny to you since the arc emits out of the torch yet the current runs to the adverse direction. This is why in TIG welding the welder uses minus electrons coming out of the torch while giving heat to the spot, so the polarity of this torch should be minus and the ground (or the metal to be melted) are plus.

The purpose is to further optimize my old analogue welder, welding current and welding wave forms when she has to weld thin aluminium sheets in butt-joint.

With my novice skill job of butt-joint with thin aluminium (like ones with 1.5mm thick) has been a tiny thorn in the throat. For one thing aluminium filler did not want to melt in to the starting welding pools when I have to weld both ends of the two sheets at several intervals, especially in welding this thinner alu sheets.

I know pros can do it better, but it's not about myself, so tried to find another way to make it better, and found one called the MIX-TIG, a way to generate alternative current for thinner aluminium while mixing some percentages of direct current to the aiming target.
Anyways this should be posted on another thread soon after this.

The composition is like this;
Attachment 35934
.
We need some handy oscilloscope one like this;
Attachment 35935

This hall sensor is named HAS-50, which allows to detect current up to 50 amperes, and is made in USA.
Attachment 35936
I thought it only detects current below 50A, but found it can do good job either for current above 50A.

Showing an oscilloscope view of an analogue wave form consists of 12.5% (this percentage is called "duty ratio") pulses when i did a DC welding with the pulse switch ON, to a sample steel sheet.
.
Attachment 35937
.
The pulses come downward to reach nearly -8.1V in this view, but we have to calculate the real amperage by making it 10 times, and replace the unit form volt to ampere, so this means the peak welding amperage is minus 81 amperes.

For a better comprehension, gave a small modification to the view above, added the wave-form-layers to see the current going further;
.
Attachment 35938
.
We can only melt steel sheet with the 'Welding Current' of the pulse, while we make repose when the pulse is off.
This repose-period when the pulse is off, we call the current of this period 'Base Current'.

Thinner sheet are easy to be melt-down, so we beginner love to use this trick, melt the target in short period, then make repose to cool the target down for a while, and repeat and repeat.

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Quote:

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Originally Posted by chy_farm

This hall sensor is named HAS-50, which allows to detect current up to 50 amperes, and is made in USA.
Attachment 35936
I thought it only detects current below 50A, but found it can do good job either for current above 50A.

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Pretty nice project. Thank you for sharing. I thought that sensor looked familiar. The maker of that sensor used to be the parent company of my work.

Cheers!

Hi Chy_Farm,
Your post is very interesting so thanx for it. I have a question. You mentioned you are using an old analogue welder. Perhaps I am wrong but my idea of an analogue welder is a welding transformer with large and adjustable spreading inductance to limit the welding current. But how are the pulses created? These 13 msec pulses with small rise and fall times need a semiconductor to switch these pulses on and off. Can you please tell something more about this "old analogue welder"? Or should I better wait for your following post?

I was about to ask the same as Carnel.
By analogue do you mean that the controls are separate rotary knobs rather than stepwise control by button presses.

Carnel and tonyfoale, good evening.

Thank you for having interests on my project. Since I am a beginner in electronics and still learning things by books and internet pro-sites, I may be wrong either, but anyways I am going to try to show what I know about my old analogue welder.
Posting an image map to illustrate my understanding below, but as far #6 I am yet on the way learning it, so I may not be able to give good replay on this.

> By analogue do you mean that the controls are separate rotary knobs rather than stepwise control by button presses.

You'r right Tony,

Attachment 35971

Chy

p.s. I see an image below which I tried to delete, was not able to...
p.p.s. Was able to do it.

Hi FEM2008, thank you for words. Glad to know you have been somewhat linked to the excellent manufacturer!
Chy

OK, Chy-Farm, your "old analogue welder" is already a more sophisticated electronic device. Now I can better understand your post. Thank you for your explanation.

A small tip about an oscilloscope that I need in this.

Some of you may feel it's too costly to buy an oscilloscope for a sort of small job like this, namely to see the wave forms of your welding. Then I think I can recommend a cheapest one like the one I use on another tool I posted here;
Attachment 36020
(https://www.homemadetools.net/forum/...tory-fan-80765)

I got this (the one you see at the upper part of my VFD) new but it still does not cost too much, nearly $40 or less.
Oscilloscope for this welder-purpose does not require too big features. We want it to see only very low frequencies like 1Hz to 1kHz (this means it's not pricey though), but one thing we need is that it must have a 'Hold Button' to keep the view when you want to stop its detection.

Chy

Quote:

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Originally Posted by chy_farm

A small tip about an oscilloscope that I need in this.

Some of you may feel it's too costly to buy an oscilloscope for a sort of small job like this, namely to see the wave forms of your welding.

Chy

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Probably the cheapest oscilloscope is software on a laptop which plots the input on the microphone jack. Unfortunately the frequency response would probably not extent down to the 1 Hz range.

Other cheap options include Arduino (and similar micros) based scopes, either stand alone with a dedicated TFT screen or even cheaper using a laptop for display and signal processing.
There are many examples of how-to on the net.

A big step up the food chain are oscilloscope boxes that connect to a laptop. I use a "Picoscope" which start from around USD 120+ and go up to $1000s. These are full featured scopes but with the advantage over dedicated scopes that the software has more processing power available from the PC.

Attachment 36021

Showing a sample of usage for this tool in my another thread below;
https://www.homemadetools.net/forum/...6-3#post163776

in which I used a comparison data of this;
Attachment 36062

Hope this can help your welding.:thumbsup:

Chy

Could you just post the make/model of your welder?

Quote:

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Originally Posted by Tooler2

Could you just post the make/model of your welder?

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Good evening Tooler, if you mean you want to see my old welder the set-up, see this pls;
https://www.homemadetools.net/forum/...g-welder-80736

Chy

I would prefer a link to the manufacture's page describing the welder, or a make/model that I can google search.

Quote:

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Originally Posted by Tooler2

I would prefer a link to the manufacture's page describing the welder, or a make/model that I can google search.

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Good morning Tooler, they do not have a site for this old welder made in early/mid 90's.
Instead I have a copy of the manual here, posting a couple of meaning page out of it. Try read them with your good imagination!

Attachment 36092

Attachment 36093