Member #128251

Member Since: April 5, 2010

Country: United States

  • Product KIT-10956 | about 7 months ago

    The one probe should be plugged into RES-1 (internally connected to +3.3V) and the other into RES-2 (internally connected to RS=1k to GND) and mode 3 selected for resistance measurement. The ‘common’ is not used as it is connected to GND. In resistance mode the A/D reads the voltage of the divider formed by R (unknown) and RS=1k. My results shows : OK measurements below 30kohm, but higher values suffer in accuracy due to the voltage divider ratio and the limited A/D resolution. e.g. 47k measures 63k, 62k measures 67k, 68k measures 127k. As this is an educational kit, it is of course not fair to compare it with a test instrument grade DMM. Voltage measurements are OK up to +30V DC (no reverse polarity as stated in the description). Current measures OK up to 300mA (the limit is due to the output swing of the LM358. The shunt resistor can anyhow only dissipate 0,25W equal to 500mA for a short while. The project was built by one of our students as part of a summer school project and the student had loads of fun and learned a lot. Thanks Sparkfun.

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