User's Manual

UT5 - 14
SAMPLE PROJECT - MONOSTABLE MODE:
In this era of digital clocks, commercially-available timing gadgets can be either amazingly cheap - or oppressively
costly. In general, we build timers ourselves instead of buying them only if a reasonably priced commercial device just
will not do the job that we want done. Most timers that are accurate to the millisecond do not have the ability to switch
an external device.
Most applications for custom designed timers are one-of-a-kind requirements. One such application comes to mind
even as I write this. The computer-driven phototypesetter used for these books requires that the paper be advanced
for 6.5 seconds after each run before cutting and processing. For the past 5 years, I've faithfully held that paper
advance button while watching the clock. Hmmm. Now I know exactly what I'll do with one of the sample UT5s I built
up while writing this booklet!
Perhaps the best example of a frequently-needed timer that seems to get more expensive as the years go by is the
photographic darkroom exposure timer. Adding a selector switch, trimmer pots, alternate timing capacitor(s) [if
needed] and a relay to the UT5 can give you a very serviceable exposure timer at a fraction of the cost of today's
typical digital models or the classic Graylab Timer.
The switch(es) can have as few or as many positions as your practical application requires. For jobs that are GEFGW
("good enough for gov't work"), a single potentiometer with a dial manually calibrated in seconds may serve routine
black-and-white print making needs perfectly well.