Panel ammeter for cutterhead current?

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aaron
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Panel ammeter for cutterhead current?

Post: # 47111Unread post aaron
Tue Jun 13, 2017 10:27 pm

I'm looking to add some nice panel ammeters to my lathe so I can monitor the head current. Does anyone have any tips/circuits they can share? I'm assuming you can't just put an AC ammeter in series without loss of sound quality.

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aaron
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Re: Panel ammeter for cutterhead current?

Post: # 47163Unread post aaron
Wed Jun 21, 2017 8:20 am

Anyone have any suggestions? I see Simpson has some low impedance meters, would that work? What are you all doing to monitor cutterhead current? I read an old post where someone tried to put a cheap ammeter in series and it affected sound quality.

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markrob
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Re: Panel ammeter for cutterhead current?

Post: # 47164Unread post markrob
Wed Jun 21, 2017 9:47 am

Hi,

It might be OK to add a meter in line with the head, but there are some considerations. You need to look to see what resistance the meter adds to the pathway. The meter is really an AC voltmeter with a shunt resistor. Also note that there is a rectifier (to convert the AC to DC) that is partly in signal path. Not sure if that would be audible, but it is something to consider. If you provide a model number or link, I can have a look and see if its appropriate for your application.

Mark

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aaron
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Re: Panel ammeter for cutterhead current?

Post: # 47167Unread post aaron
Wed Jun 21, 2017 10:40 am

How about something like this? http://www.simpsonelectric.com/images/File/datasheets/rectangular_datasheet.pdf
Page 8, the first one under "AC Ammeters", part #02270

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markrob
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Re: Panel ammeter for cutterhead current?

Post: # 47168Unread post markrob
Wed Jun 21, 2017 11:51 am

Hi,

That should work. Keep in mind its pretty slow responding (1.5 seconds), so you may not see short term peaks. If you want faster response, you would need to roll your own system with a shunt resistor, op-amp/ precision rectifier circuit and a voltmeter calibrated to read amps. Then you can tweak response times as needed.

Mark

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TheCrates
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Re: Panel ammeter for cutterhead current?

Post: # 47170Unread post TheCrates
Wed Jun 21, 2017 1:27 pm

Bought these for the stylus heating, probably it work for cuttingheads too.

Didnt install it yet, just tried and measured, very accurate.

http://www.ebay.de/itm/Red-Blue-Dual-LED-Display-4-Bit-DC-0-33V-3A-Digital-Ammeter-Voltmeter-TE544/331915160102?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

Cheers

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