R19 and R20

2nd harmonics for the masses

R19 and R20

Postby Spoon109 » Sun May 10, 2015 7:55 pm


I have kind of noob question.

R19 and R20. The BOM calls out a 0.75 ohm 10% tol. wirewound resistor (71-CW2B-0.75).

The resistors I got from Mouser are part marked correctly, but it measures 0.9 ohms. Which is +20% tol. Is it ok to use this in my Get Set Go build?
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Re: R19 and R20

Postby EWBrown » Sun May 10, 2015 8:01 pm

With such low values of resistance, the resistance of the meter leads will add a couple of tenths of ohms resistance, which will then become quite noticeable.

Some DVMs allow this factor to be "zeroes" out.


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Re: R19 and R20

Postby Geek » Sun May 10, 2015 9:35 pm

The resistors are probably correct and your meter is confused by lead resistance.

You can zero out the lead resistance on an analog with the "Zero" control.

On a DMM, such as my Triplett, you put the probes together and press the "Delta" button when it hits a reading of 0.000.

Your DMM is probably similar, check the manual.

If you have an el-cheapo DMM with no ohm-zero function, forget about measuring anything under 10-15 ohms.

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