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Dave,
It would be a rare ammeter, indeed, that would have a "highest
current" indicator. Using an ammeter to indicate end-of-travel relies
on the fact that an electric motor draws the most current when almost
stalled. Thus, a motor that is only pulling 3A to turn the blade
can be expected to jump up to 6 or more amps as the load increases
when the mechanism approaches its limits. Depending on how quickly
the motor drives the mechanism, you could see the current rises over
a few seconds as it approaches end-of-travel.
HTH,
Dale R.
David Staten wrote:
Jim...
I am following up on a previous post from November that is attached below. You discussed using an ammeter and resistor to indicate relative power draw as an indication of how many amps your IVO was requiring.
One question. Is this indication (using the equipment you have selected) ONLY when current is flowing? or does the needle stop where it last was indicated (as in, to make an adjustment that only toggles the switch for a moment, do you have to take time out at look at that gauge that very instant, or does it have some "memory" of position, like a trim indicator would?
Im guessing its a momentary indication, but wanted to ask anyways.
Dave
James Maher wrote:
Sure thing John.
The link below is for the one that I am using.
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=276342&e_categoryid=643&e_pcodeid=03901 <http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=276342&e_categoryid=643&e_pcodeid=03901>
There are several styles but I like this one because it shows direction and relative amount
without any actual values.
You will have to insert a 0.015 ohm 5 watt resistor in series with one of the wires that drives the motor, as a current sense. The meter is then connected across this resistor.
I used the one in the link below, also from Mouser.
http://www.mouser.com/index.cfm?&handler=data.listcategory&D=* <http://www.mouser.com/index.cfm?&handler=data.listcategory&D=*>71LVR50.015*&terms=71-LVR5-0.015&Ntt=*71LVR50.015*&Dk=1&Ns=SField&N=0&crc=true
This was not all my idea.
I saw a gentleman at Oshkosh a few years ago with an old ammeter that did the same thing.
I just updated to the newer style meter.
It beats waiting for the circuit breaker to pop.
Jim
*//*
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