Digital amp meter install help

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Digital amp meter install help

Postby gene » Wed Sep 12, 2012 11:13 pm

So I'm finally getting around to installing an amp meter. I've got the 3 digit 100mA meter from lightobject. I'm not quite sure on how to wire it in. I've attached the picture of their example install. i have the isolated power module and a shunt to go with the meter itself.

Image

I know the input+ for the meter would be attached to the negative wire coming off the laser tube. it looks like the shunt has one side wired to the negative from the laser as well with the other shunt wire going to ground?
I'm unsure of where to pull the input+ for the power module from. I've got the 3 axis driver board so I was thinking of finding a 5volt source somewhere to piggyback on. Is there anything else I'm missing that is needed before I destroy something from a short?

Thanks very much,
Gene
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Re: Digital amp meter install help

Postby mattrsch » Thu Sep 13, 2012 3:27 am

You're on the right track. you basically cut the ground wire for the laser power supply and insert the shunt on that line. The current meter input + will go on the tube side of the shunt and the - will go on the power supply side of the shunt. The input + on the power module will tie to +5V somewhere. Your laser power supply should have one at the front. Definately don't hook it up to the laser tube + :lol:
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Re: Digital amp meter install help

Postby Techgraphix » Thu Sep 13, 2012 7:44 am

Is this meter a currentmeter or a voltagemeter? If it is a currentmeter there is a buildin shunt. The way you draw your circuit is for a voltagemeter.
Maybe this helps? (this is how my currentmeter is connected)
Currentmeter.jpg


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Re: Digital amp meter install help

Postby gene » Sat Sep 15, 2012 2:12 pm

it's close to this: http://www.lightobject.com/3-digit-Mini-Blue-LED-DC-100mA-meter-Ideal-for-CO2-Laser-power-indicator100mA-P457.aspx.
Actual item was: EPM-3D100MVB 3 digit Mini Blue LED DC 100mV meter. Ideal for CO2 Laser power indicator(100mA)
I'm gonna give installing it a shot today and see what happens
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Re: Digital amp meter install help

Postby georgehine » Sat Sep 15, 2012 7:53 pm

I bought a digital amp meter that is soposed to be 200ma however when i hook it up to the laser it reads 1 like it is over limit on what it can read. Then when i cut at 100% it read 06.0 can anyone help me figure this out.
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Re: Digital amp meter install help

Postby gene » Sun Sep 16, 2012 5:43 pm

mattrsch wrote:You're on the right track. you basically cut the ground wire for the laser power supply and insert the shunt on that line. The current meter input + will go on the tube side of the shunt and the - will go on the power supply side of the shunt. The input + on the power module will tie to +5V somewhere. Your laser power supply should have one at the front. Definately don't hook it up to the laser tube + :lol:



I'm close. I've drawn how I think I'm supposed to hook this up. in this modified image. What do you think?
Image
Last edited by gene on Sun Sep 16, 2012 6:27 pm, edited 1 time in total.
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Re: Digital amp meter install help

Postby mattrsch » Sun Sep 16, 2012 6:13 pm

Yes, reconnect both cut ends to the shunt. The ground on the laser power supply will go from the power supply to one side of the shunt, then from the other side of the shunt to the ground side of the laser tube.
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Re: Digital amp meter install help

Postby gene » Sun Sep 16, 2012 6:33 pm

mattrsch wrote:Yes, reconnect both cut ends to the shunt. The ground on the laser power supply will go from the power supply to one side of the shunt, then from the other side of the shunt to the ground side of the laser tube.


Edit: @5pm So my big problem was that I couldn't piggy back on the 5volt from the laser power supply. The laser would not recognize a working circuit and the ground and WP light would not light up. Once I took the 5v from the control board (water supplly 5v) I am now getting a working laser again. I hooked up everything per image 2 and the meter isn't showing any change when firing laser so i'm going to try hooking up per image 1

edit 2: 5:42pm est - Yep image 1 was the correct way to install. I'm now getting readings when firing the laser. When test firing using red power supply button I'm getting 26.2-26.9 on the meter which I'm assuming is voltage and not amps
Last edited by gene on Tue Sep 18, 2012 9:39 pm, edited 1 time in total.
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Re: Digital amp meter install help

Postby mattrsch » Sun Sep 16, 2012 9:52 pm

The number it is showing is most likely mA. How powerful is your laser tube? Most 40W tubes should be limited to about 18mA. Because of this I never go above 60% power on my controller
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Re: Digital amp meter install help

Postby gene » Sun Sep 16, 2012 10:31 pm

mattrsch wrote:The number it is showing is most likely mA. How powerful is your laser tube? Most 40W tubes should be limited to about 18mA. Because of this I never go above 60% power on my controller


it's 40 watt so it should be 18-20 mA I figured it was overdriving it with the power supply test button and when using mach 3 because I was getting weird issues randomly like the beam moving it's exit point on the tube and messing up mirror alignment. I'm going to vector cut with the Retina Engrave usb card at 100% power to see what it is currently running it at. I need to do some oak engraving so hopefully I can get some decent depth of cut. At the moment I'm only getting enough depth as a fingernail edge. I'll adjust it until I get it to a decent depth of cut or 20mA whatever I reach first.
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