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Digital VOM


We have a dozen of the $59 Radio Shack Digital VOM's and for student lab
use, we didnt care much about their quality.  But after two years of
abuse, I am more and more impressed with these things:

1)  THey have a serial port interface so that any PC becomes a DIgital
Oscope (for slow signals) with included software.

2) THey run forever on a 9v battery.  Most of them are still on the
original battery (more than 2 years).  THey auto shut off if not in use,
but if the voltage is changing, then they will stay on forever.  Thus,
very long battery life and no frustrating shutoffs on long monitoring.

3) Doing critical measurmemnts tonight on our satellite, we figured we
would compare many of them and choose the two that were closest together.
The first two we tried read 300.1 and 300.1 MA!  Thats better than 0.03%
relative accuracy.  We were shocked to see them even close for Radio
Shack... but they were identical! (We dont have anything better with which
to compare absolute accuracy)...

4) We took them into a freezer at 0 deg F and when we brought them out
(July Humidity), they were dripping wet in condensation.  We opened them
up to dry out, but the INSides were bone DRY.  THus very good air seal for
a non o-ring plastic case.

5) I have left them on the dashboard of the car in summer heat.  The LCD
display gets black, but no permenant damage.

Overall, I am amazed for $59.  I think that was a sale price, but they are
only $69 regularly I think.  I have no interest in this, but just thought
others might learn from our experiences.  I cannot complain about them one
bit...  Oh, they are the bright yellow ones.  CAT No. 22-805.  I believe
the current model is slightly different, but I cannot see any
difference on the outside.  Model number is probably different...

For what it's worth...
de WB4APR, Bob

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