Tag Archives: comparator

Un-improving range on the infrared channel

It turned out doing software UART was a terrible idea.  The processor is way too slow to support a reasonable baud rate.  I did figure out how to use a comparator though: the key phrase I was missing was “rail-to-rail.”  That means that inputs can be in the full voltage range from ground to Vcc.  Another handy phrase is “push-pull,” which means that the comparator can output 0 and 1; in contrast, an “open collector” comparator can only output 0, and needs an external resistor to pull the output to 1.

I bought a rail-to-rail push-pull comparator, the MCP6541, and tried it with the receiver circuit, and sure enough it increased the maximum range significantly.  Unfortunately it also increased the minimum range significantly.

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