WP34s Repurposing Journey PhotoJournal

[MarkHaysHarris777]

(02-05-2015 02:11 PM)rprosperi Wrote:  ... It's clear this is the most thoroughly instrumented flashing "cable" to date.

Seems bold to label it "1.0" with only 1 decimal place. I would have guessed something like 1.0.002.07.d, but I suppose that would require a much smaller font.

Well, not quite. Turns out my voltage line monitor circuit has a little small snag that needs fixing... if the line voltage to the 34s falls below 2.8 volts (which can adversely affect the flash) for even a short time (milli - micro seconds) there might be a problem with the integrity of the flash. The voltage monitor needs a latch; consider the following modified schematic of the 3v line monitor:



The latch is used on 'output' this time, vs input; but its the same circuit as the reset and erase debouncers:

... if the 3v line voltage faults (below 2.8v reference) for even a short time the LM339 provides a ground shot to the pull-up input of the bistable latch. The latch toggles (and holds) lighting the red diode until the reset switch is pressed again. We will not know 'when' the fault event occurred necessarily, but we will not 'miss' the event even if very brief.

Just to be complete.

Cheers