The Handheld Oscilloscope is
A handheld Oscilloscope (or other type) is the best investment you will
ever make and a portable handheld type is the most useful.
an Essential Piece of Test Equipment
For Electronics and Microcontroller Work.
As well as the normal ability to measure voltage and frequency
digital scopes allow you to easily record transient or long term
signals and some allow fourier spectrum analysis.
need to break
the bank to get one and they
will pay off for years to
In microcontroller work you will often want to find a glitch or record
a waveform so you can see exactly what sequence of event
occurred and the Digital Scope is Ideal for that.
For example debugging serial protocols such as RS232 and I2C is much
easier with a digital
scope - if you don't have one you'll have to use
the simulator in the software to check it's operation and that can be
unreliable as in the 'real world' things often don't work as you expect
e.g. capacitive loading, inputs drawing too much current etc.
Note: Without a
scope much of electronics is a wing and a prayer - I don't care what
have got the worst, oldest, lowest bandwidth scope
it is STILL
infinitely easier than
guessing what's going on.
I'll just talk a bit about the three different types of oscilloscope
you can buy these are the
- PC based
on Signals, Probes and Bandwidth
POINT1: Any scope (even a handheld oscilloscope) that you buy whether
it is a high end on or a low end one
if it says it has a bandwidth of X (or a sample rate of X) then you
will only get to view a reasonable waveform AT
A MAXIMUM OF X/10.
So if you have a 500MHz capable scope you are only going to easily see
50MHz signals maximum. Similarly 10MHz ones only show 1MHz
signals properly and it's the same for the sample rate i.e. treat the
sample rate the same way.
Note: there is one
cheat and that is for the analogue scope where there is a x10 button
(essentially this speeds up the signal that controls how the cathode
beam crosses the screen i.e. it moves it faster so you can see more
waveform - the disadvantage is that the scope is uncalibrated i.e. the
signal is not guaranteed accurate. It's sometimes useful.
POINT2: Analogue input bandwidth - THIS IS DIFFERENT TO THE INTERNAL
BANDWIDTH capability OK. The analogue input limits the input
signal separately from the internal bandwith or sampling rate.
So if you use a scope with a small input bandwidth don't expect to see
a signal above that bandwidth (OK it's a capacitive filter so you will
see a reduced signal at 3db/octave lower - essential you won't get a
real signal) because it is filtered.
REMEMBER: The sample rate and scope bandwidth are used to SELL
HOW GOOD THE SCOPE IS - but it means SQUAT.
It is the BandWidth (or sample
rate) divided by 10
that is THE REAL
CAPABILITY of the scope
One other point: Remember fourier transforms where all signals are made
up of combinations of pure sine waves well the input bandwith (and
internal bandwidth/sample rate) act as high frequency filters.
So you loose high frequencies - that means if you look at
square waves THE EDGES
BECOME ROUNDED as the high frequency information is lost.
Just remember what you see is never what is really going on and it
depends on the scope specs, the probe specs AND how you
connect the probe to the signal.
POINT3: OK one more point - you know that great big loop of
wire when you connect the probe to the signal and the probe's ground
ten miles away (because the ground pin is over there on the other side
of the board) - well you are creating a magnetic induction loop
(remember the metal detector?).
Essentially any electrical activity inside/through that loop induces
another signal (noise) into the circuit (into the scope
input). So keep the ground loop small - the best way is to
connect to a ground as close as possible to the signal.
Professional probe kits have little springy wires that wrap
around the end of the probe (Ground area) letting you create the
smallest loop possible i.e. receive the best signal capture.
Right I've run out of points so lets talk about scopes (at last).
Lets start with the analogue scope.
I have put this scope up to show you the most basic scope you can buy
and I would not recommend you buy this for any serious work.
It's very bluky and far more difficult to use than a handheld
oscilloscope. The best feature is that it has two input
Lets look at the relevant specifications (you can see all of them by
clicking the image above):
Bandwidth : (-3dB): DC: 0～10MHz, AC: 10Hz~10MHz
So that's really 1MHz signal view
Sweep rate : sweep rate: 0.1μs/div～0.1s/div ±5%
So that 1/0.1e-6 allows a 10MHz maximum frequency
At the time of
writing this it costs $149.95
Digital HandHeld Oscilloscope
This handheld oscilloscope has the following features:
So as well as being a full oscilloscope it is a recorder and DVM all in
- Sample rate : 10MHz (You'll really only get a good
view of 1MHz)
- Analogue BW : 2MHz
- Timebase up to 1 hour per division.
- It's a DVM.
- Has easy frequency readout using markers.
- Has memory recorder function i.e. it is a DSO.
- Has a memory signal compare function.
At the time of
writing this handheld oscilloscope costs $169.95
here to order the handheld oscilloscope
Here's the handheld oscilloscope full spec:
here to order
- 10MHz sampling rate
- 0.1mV sensitivity
- up to 2MHz analogue bandwidth
- 5mV to 20V/div in 12 steps
- 200ns to 1hour/div time base in 32 steps
- full auto set up
- trigger mode: run, normal, once, roll, slope +/-
- X and Y position signal shift
- DVM readout with x10 option
- audio power calculation (rms and peak)
- dBm, dBV, DC, rms ... measurements
- signal markers for Volt and Time
- frequency readout (through markers)
- recorder function (roll mode)
- signal storage (2 memories)
- LCD: 128x64 pixels / high-contrast
- up to 20h on alkaline batteries
- power supply: 5 x 1.5V AA battery or Nicd / NiMH
- includes battery charging circuit
The last on is the PC Based Oscilloscope
This one connects through the parallel port and has the following
12MHz 3db point and it's definately not as portable as the handheld
- Parallel port - check you've got one!
- Not portable.
- Slightly worse input sensitivity (10mV) than the
which has 0.1mV
- Uses the PC - you probably want to use it for
At the time of writing it costs $189.95
- Record all data to the PC for full analysis.
- Does spectrum analysis - very useful for opamp db
- Auto setup - push a button and it will look for a
- Record and display all screen data - useful for
Here to order
The full spec is:
- Includes 110VAC Power Adapter
- 1 channel
- Input Impedance: 1Mohm / 30pF
- Frequency Response: 0Hz to 12MHz (± 3dB)
- Step Markers for Voltage, Time and Frequency
- Vertical Resolution: 8 bit
- Auto setup function
- Optically isolated from computer
- Record and display of screens & data
- Supply voltage: 9 - 10V DC / 500mA
- Dimensions: 9" x 6.5" x 1.8"
- Weight: 14oz
- IBM compatible PC
- Windows 95, 98, ME, (Win2000 or NT possible)
- SVGA display card (min. 800x600)
- Free printer port LPT1, LPT2 or LPT3
- CD Rom drive
- Ttimebase: 0.1µs to 100ms per division
- Trigger source: CH1 or free run
- Trigger level: adjustable per ½ division
- Input sensitivity: 10mV to 3V per division
- Record length: 4096 samples
- Sampling frequency: 800Hz to 32MHz (Real time)
- True RMS readout (only AC component)
- Timescale: 20ms/div to 2000s/div
- Max record time: 9.4hour/screen
- Automatic storage of data
- Automatic recording for more than 1 year
- Markers for time and amplitude
- Zoom function
- Frequency range: 0 .. 400Hz to 16MHz
- Linear or logarithmic timescale
- Zoom function
here to order
I would recommend the handheld
oscilloscope for general lab bench work and the PC
Based oscilloscope for more in-depth analysis of individual
Remember each of the above scopes is great value because they are about
the same cost as a good multimeter.
from Handheld Oscilloscope and others to
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