Here's a close-up of the PO2 display, which is nothing
but a cheap plastic box containing a 9v battery, a switch,
and a DPM125 200mV LCD display. I filled the box with a
re-enterable urethane potting compound, and used a
waterproof switch cover from APM HexSeal, which is
theoretically rated to 10,000PSI or something rediculous
like that. The re-enterable urethane seemed like a
good idea at the time, but when the battery eventually
died, trying to dig it out of the potting compound proved
impossible, and I ended up cracking open the cheap plastic
box and making a new one.
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