IEEE Spectrum March, 2012 - 19

leads,-opto-isolated-USB-cable,-a-decent-
canceling-out-residual-capacitance-
multi-meter,-or-DMM.-Apply-a-signal-
manual,-and-PC-software-on-CD-ROM.
when-measuring-capacitor-values-or-
and-the-unit-quickly-selects-vertical-
All-three-of-these-handheld-scopes-
for-matching-resistors.-In-scope-mode,-
and-horizontal-settings-to-show-you-a-
are-intriguing,-for-different-reasons.-
you-can-view-measurements-of-current,-
couple-of-cycles-of-the-waveform.-Nice!-
For-pure-sex-appeal-and-as-a-tinkerer's-
something-you-can't-do-on-most-scopes.-
You-can-turn-it-off,-of-course,-and-you-
delight,-the-DSO-Quad-is-something-to-
Alas,-even-with-contrast-and-
can-save-waveforms-to-memory,-too.
behold.-As-a-practical,-basic-instrument-
brightness-cranked-way-up,-the-screen-
This-is-a-solid,-no-frills-package-
is-dim-and-washed-out,-although-it-looks- that-offers-ease-of-use,-better-bandwidth-
that-slips-effortlessly-into-a-pocket-
and-accuracy,-and-durability-in-your-
better-under-a-lamp.-Worse,-the-scope-
or-any-bag-of-tools.-It-comes-with-
pocket,-the-Velleman-gets-my-vote.-As-
is-always-DC-coupled,-even-when-set-to-
a-USB-charging-cable,-a-switchable-
a-bench-meter-or-for-a-full-size-tool-kit,-
measure-AC.-This-design-flaw-severely-
10x/1x-probe,-and-a-handy-calibrator-
the-Uni-T-combines-several-instruments-
limits-the-instrument's-use-as-a-scope,-
square-wave-terminal-on-the-back-for-
into-one-and-adds-some-unusual,-useful-
because-AC-coupling-is-a-critical-
setting-the-probe-compensation.-The-
features.-It's-a-viable-option-if-you-can-
manual-is-brief,-but-there's-more-info-at- function-for-viewing-signals-riding-
live-with-its-limitations.
on-DC-voltages.-The-only-way-around-
Vellemanusa.com-and-Hps140.com.
More-pocket-scope-models-are-
the-problem-is-to-build-a-probe-with-a-
Calling-the-third-oscilloscope,-the-
appearing-almost-weekly.-Check-eBay-
switchable-blocking-capacitor-in-it.
Uni-T UT81B (3),-a-pocket-scope-
for-the-latest-ones.-Measure-on!-
The-UT81B-comes-in-a-nice-zippered-
might-be-accurate-if-you've-got-very-
case,-with-AC-adapter,-banana-plug-test-
large-pockets.-While-smaller-than-most-
-Michael Jay Geier
handheld-scopes-of-the-past,-
it's-much-bigger-than-the-
	
SEEED	DSO	QuaD	
VEllEman	HPS140i	 uni-T	uT81B
other-two-units.-It-looks-like-
an-overgrown-multimeter.-
Dimensions	
98	x	60	x	15	mm	
114	x	74	x	29	mm	
200	x	100	x	48	mm
And-that's-basically-what-it-
	
(3.9	x	2.4	x	0.6	in.)	
(4.5	x	2.9	x	1.1	in.)	
(7.9	x	3.9	x	1.9	in.)
is-a-digital-multimeter-that-
Weight	(with	batteries)	
102	grams	(3.6	oz.)	
200	grams	(7	oz.)	
498	grams	(17.6	oz.)
can-display-waveforms.-The-
Battery	type	
Lithium-ion	
Nickel-metal	hydride	 Alkaline	AA
Uni-T-offers-both-DMM-and-
scope-modes-and-can-read-
Battery	life	
8	hours	
6	hours	
12	hours
voltage,-current,-resistance,-
Screen	type	
Color	active	matrix	
Mono	passive	
Mono	passive
diode-voltage-drop,-frequency,-
Resolution	
400	x	240	
128	x	64	
160	x	160
and-capacitance.-True-to-
Input	connector	
MCX	(minicoaxial)	
BNC	
Banana	plug
its-multi-meter-roots,-it-uses-
banana-plugs-for-input.-An-
Probes	included	
Two	10x/1x	
One	10x/1x	
Test	leads
optional-BNC-converter-is-
Tilt	stand	
No	
No	
Yes
mentioned-in-the-manual-but-
Number	of	channels	
2	analog;	2	digital	
1	
1
is-not-included.-It-isn't-shown-
Real-time	sampling	rate	
72	MS/s	(144	MS/s,	single-channel)	
40	MS/s	
40	MS/s
on-Uni-T's-website,-either.
The-user-interface-
Bandwidth	
3-11	MHz	(depending	on	voltage	range)	 10	MHz	
8	MHz
is-well-considered.-Like-
Fastest	time	base	
0.1	µs/div	
0.25	µs/div	
0.1	µs/div
the-Velleman,-this-scope-
Input	coupling	
AC	and	DC	
AC	and	DC	
DC	only
offers-auto-setup,-and-it-
can-save-waveforms-to-
Most	sensitive	range	
50	mV/div	
1	mV/div	
20	mV/div
memory.-It-even-includes-
Maximum	safe	input	
80	V	
100	V	
1000	V
PC-software-and-an-optoMeasurement	cursors	
Yes	
Yes	
No
isolated-USB-cable-for-use-
Internal	calibrator	signal	
Yes	
Yes	
No
as-a-real-time-PC-scope.-
One-nice-DMM-feature-
User-upgradable	firmware	
Yes	
No	
No
is-the-"relative"-mode,-
Downloads	to	computer	
Yes	
No	
Yes
in-which-the-displayed-
Real-time	data	to	computer	 No	
No	
Yes
reading-is-subtracted-from-
Approximate	price		
US	$200	
$250	
$180
the-values-to-be-measured.-
It's-especially-useful-for-
ms/s-megasamples per second; µs/div-microseconds per division; mV/div-millivolts per division
spectrum.ieee.org

mArch 2012 * iEEE SpEctrum * NA

19
http://www.Vellemanusa.com http://www.Hps140.com http://spectrum.ieee.org
Table of Contents for the Digital Edition of IEEE Spectrum March, 2012
