Amp Meter for A/C welder

**drivermark** · Feb 28, 2019, 12:01 PM

Hey Guys,

I have an old A/C buzz box that I would like to install a meter/gauge/readout of some type to indicate the amperage output.It is an old Campbell Hausfield unit that Walmart used to sell back in the '90's. The "indicator" it came with is just a pointer and to adjust amperage you turn a little crank/handle that makes about a turn and a half before the needle starts to move, so I have no idea what the actual amperage is.

So my question is ... How can I make, beg,borrow, buy, steal a readout (preferably digital but I'm not picky) that will indicate the amperage fairly accurately.
I've tried the search feature on the sight and Google but so far no luck.

Thank you in advance for any help on this.

Mark

**rebuilder1954** · Feb 28, 2019, 05:16 PM

Mark,

since you have an AC welder, a clamp-on AC ammeter will do the trick. i use one on my Lincoln AC-225, and it works fine. it only reads when the arc is struck, of course, but that's the nature of the beast.

another option is units like this from Amazon, ebay, etc. I bought a 300 Amp analog meter for my Lincoln, but don't have it hooked up yet. here is a link to a 200 Amp item (i have not tried this one).

https://www.amazon.com/DROK-Multimet...52-spons&psc=1

Hope this helps: good luck.

Bob R

**greyhoundollie** · Feb 28, 2019, 06:24 PM

Hi Mark,

I just read Bob's Reply and his clamping ammeter is probably the easiest and quickest item for you. However, I am not sure if you are aware of how the amps work while you are welding. The amps flowing will vary by a bunch of different factors, the change in the difference of the gap between the end of the rod and the surface you are welding to. The temperature of the rod as it heats up/ cools down while welding. Difference in temp of the surfaces you are welding. Temp of the welding leads changing as the amp flow changes while welding. And about 10 or 20 more things. It will always be a "dance" to watch while things are in motion. Then of course, it is hard to look at the amp meter while you have your hood on while you are welding. It will probably require a "buddy" to watch the meter while you are welding. The "sound" of the arc, the "hum" of the welding machine, the "sticktiscity" of the rod to the work surface etc are the things that regular welders learn by experience to "feel" if things are set right for each particular job are things that a meter has trouble teaching you. I really am not trying to shoot your idea down. I just want to add a few things that you will need to get you amp meter to help "tell you" as you tackle each project.

Good luck and have fun with it!

Richard

**Frank S** · Mar 4, 2019, 09:03 AM

Well unless someone is doing coded AWS-D1-1 in one of the grades there really is no need to know the exact welding current / voltage. However most machines with manual indicators can be a bit dodgy when it comes to indicating the current range the machine is set at.
Those of us who have been welding for 40 ,50 or 60 years learned to weld long before there was any sort of current & voltage meters to tell us our settings. We had to do a scratch arc test on a sample test plate to get our machines adjusted where we were comfortable Then changing from flat to vertical to overhead welding we learned from experience that the machine we were using had to be adjusted up or down accordingly and to alternate our arc length to produce the best penetration while having the least amount of arc blow (splatter) Sometimes this could become quite tedious.
There is nothing wrong with desiring to have a way to know in advance where to preset a machine close to where we want the welding range for a given electrode size to make our welds, which is also different for the thickness and type of metal we are welding.
Meters can be installed to give both voltage and current readings. However there will be no amp or current reading unless the welder is actually welding at the time. the same goes for voltage this is going to only show the open circuit voltage until an arc is struck.but knowing the OCV can be helpful for pre-selecting a rough setting.
A lot of machines only have a range selector and no fine adjustment, then there are some that have a much wider range of adjustments even to the point of being able to control the wave form and hz also there are constant current and constant voltage machines.
I once owned a diesel drive that I could lower the voltage down to an obscene level and maintain 400 amps and vice versa
it could also briefly hold the voltage as low as 3 VDC with 800 amp output for a few seconds allowing me to use it for heavy duty spot welding or switch to AC with a high frequency for Tig welding, but even as lavishly equipped as it was the meters still only gave a rough idea unless I was striking an arc.

**Sleykin** · Feb 28, 2019, 08:03 PM

As others stated, a clamp on amp meter is the quick and dirty way. I would use a carbon pile to watch the amp meter as you adjust it so you know how to match your needle adjustment to an actual amperage. Then just use the needle. You may also find the the needle creeps down more after you lower it so bang it a bit to see what the backlash does and where it is.

**Frank S** · Feb 28, 2019, 10:38 PM

A volt meter to read the open circuit voltage will be more useful but you will have to learn a correlation with the OCV and the actual heat you are welding at by welding up several test samples at various settings until eventually you will be able to adjust the meter to where you want it AN AC amprobe hung on the lead while welding will give you a general idea but you really need someone else doing the welding while you read the meter. if you have that and the volt meter you can see where the volt meter reads while welding as well But you need someone who can actually weld not just dab while trying to strike an arc.
Once you have everything figured out you can buy or make a relunctance coil to place around 1 lead connected to 1 side of your meter and the other side connected directly to the other lead you will have to figure out how many ohms of resistance you will need to get the correct reading on the amp meter you mount on the machine

**Big Sexy** · Mar 2, 2019, 08:18 PM

Your question states AC buzz box. I am assuming it is not a rectified DC voltage welder? If it is true AC like the others have stated works good. But I will add, if you spend a few dollars more than the cheapest you can buy, pick a meter out that has a MAX HOLD feature. That way you can attach the clamp around the welding lead and start to weld. After a short bead is laid down, stop and check the max amperage on the meter, then you can “titrate for effect” adjust accordingly.

Now if it is a DC voltage welder, you will need a meter like these, https://trumeter.com/apm/products/shunt-meter/.

**Sleykin** · Mar 2, 2019, 10:10 PM

Or there are a wide variety of panel meters on eBay. one like this would be a cheap and dirty way to go too.
https://www.ebay.com/itm/Digital-LCD...:pf:1&LH_BIN=1
Don't know the seller, but it is a good example.