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td0g / ballistic_chronograph_mk2

A 3D-printed ballistic chronograph that can measure high-powered rifle rounds
https://td0g.ca/2020/04/19/ballistic-chronograph-mk2-diy/
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LightGateSensor missing R9 designator from BOM #4

Open TheAxeDude opened 1 year ago

TheAxeDude commented 1 year ago

Im fairly new to getting PCBs manufactured, and had a few of the LG0 made up. I noticed a spot on the PCB for R9 - which hasnt been populated in the BOM. Looking at the schematic, it should be the same as R1- R8.

Can anyone confirm if this is correct?

dezanche commented 1 year ago

R9 is the pull-up resistor, which is needed unless you cut the JP1 jumper. I didn't find a specific explanation of why you might need to do this. Two possibilities are if that pull-up resistor is present elsewhere (e.g., on the Arduino or other board you use to measure the transit time between light gates), or if you're using multiple LG0 boards in parallel to increase the viewing window (in which case only one is needed and if you didn't cut it the combined resistance would be half = 330k/2 ohm). Hope this helps.

TheAxeDude commented 1 year ago

@dezanche thank you for pointing that out, it seems to make sense. Ill post-back if I figure out more, or manage to get to a working state.