Frequency Counter: BNC Input
Download BNC input schematic circuit schematic
PNG image (405x515 as seen below): bnc-input.png
High-quality PDF: bnc-input.pdf
Permission to copy and use this schematic is hereby granted provided credit is given where it is due.
This is a CMOS-compatible (and hopefully also TTL) input featuring
over- and under-volatage protection. Schmitt triggers are used to allow
for input with long transition times. Verified to work up to 30MHz.