Way back in post #2 I provided the OP a little cartoon. I clearly show the load voltage measured across the load. I subsequently mentioned the voltage measured at the source and across the load will not be the same. This is because of the burden voltage drop of the ammeter. The object of this exercise in futility (
) is to get the OP to understand what is going on.
Since the OP is using DMMs I did this little science experiment using some DMMs. I used a pair of identical Fluke 87 DMMs. The power source was a Lambda Model LP-532-FM 0 to 40 volt and 0 to 3 amp supply. Now as to the 100 Ohm resistor I took that seriously and coincidentally inline with what KISS mentions:
Yeah, I saw one on my computer table a few min ago.
I used a precision L&N laboratory grade (oil bath) good as gold fancy resistor with... four terminals.
So here is what we have.
Source Voltage = 1.500 volts.
Load Voltage = 1.475 Volts
Current = 14.75 mA.
The numbers make sense to me.
I increased the power supply voltage output until I had 1.500 volts dropped across the precision 100 Ohm load (of course measuring the load voltage at the 4 wire voltage terminals). This is what I got:
Source Voltage = 1.525 volts (an increase of 25 mV)
Load Voltage = 1.500 Volts
Load Current = 15.00 mA.
Again, the numbers make sense to me.
Now considering a kitchen table setup on a Sunday afternoon while enjoying beer I see the results as making sense to me.![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
<EDIT> Alas........
This is fun stuff huh? </EDIT>
Ron
Since the OP is using DMMs I did this little science experiment using some DMMs. I used a pair of identical Fluke 87 DMMs. The power source was a Lambda Model LP-532-FM 0 to 40 volt and 0 to 3 amp supply. Now as to the 100 Ohm resistor I took that seriously and coincidentally inline with what KISS mentions:
Ever seen a 4-terminal resistor? They exist.
Yeah, I saw one on my computer table a few min ago.
So here is what we have.
Source Voltage = 1.500 volts.
Load Voltage = 1.475 Volts
Current = 14.75 mA.
The numbers make sense to me.
I increased the power supply voltage output until I had 1.500 volts dropped across the precision 100 Ohm load (of course measuring the load voltage at the 4 wire voltage terminals). This is what I got:
Source Voltage = 1.525 volts (an increase of 25 mV)
Load Voltage = 1.500 Volts
Load Current = 15.00 mA.
Again, the numbers make sense to me.
Now considering a kitchen table setup on a Sunday afternoon while enjoying beer I see the results as making sense to me.
<EDIT> Alas........
the problem got corrected by measuring the voltage across the resistor... exactly as
it mentioned above and not at the power supply, now the results from most multimeters
match the result from my calculations.
it was so simple...
This is fun stuff huh? </EDIT>
Ron
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