Macrofab Engineering Podcast

MEP EP#287: Biased For ArduinoBias Test System Got the first board built and installed on an arduino First tests were a success Arduino library - works “first” time Adien Akhmad 2.5V reference voltage MCP1501T-25E/CHY 0.1% initial accuracy 50ppm drift I have measured a handful of these at work and have found the output to be within this range - 2.498 Arduinos and USB are noisy Resistive measurements via constant current Opamp driven constant current source 1mA output current measured @ 1.001mA with a 1k resistor Output current is somewhat load dependent - higher at higher resistance values Possibly should have gone with a parallel opamp config Validation Voltages seem to be reading well. 0 to 300V was within 1% of meter Small “offset” reading This is due to input buffer amp offset. Datasheet calls out 125 as typical and 750 as max I have seen the 100 to 400uV range Will calibrate out When doing a simple offset correction I can get 0.00000X readings For resistive