Recommendations for Oscilloscope.

[Daniel Pitts]

As I get more advanced at creating circuits, I can see the benefit to
owning an Oscilloscope. I'm on a fairly tight budget, and was hoping to
get a recommendation on a cheap oscilloscope that is "good enough" for
hobby work. I've used one at school years ago, which probably had more
bells and whistles than I would ever need.

What features are essential for a hobbiest? What can I do without? Any
particular brands that are cheap but reliable?

Thanks for suggestions,
Daniel.

 

[Winston]

On Fri, 10 Aug 2012 14:45:11 -0700, Daniel Pitts wrote:

As I get more advanced at creating circuits, I can see the benefit to
owning an Oscilloscope. I'm on a fairly tight budget, and was hoping to
get a recommendation on a cheap oscilloscope that is "good enough" for
hobby work. I've used one at school years ago, which probably had more
bells and whistles than I would ever need.

What features are essential for a hobbiest? What can I do without? Any
particular brands that are cheap but reliable?

Thanks for suggestions,
Daniel.

For what it does, this is Dirt Cheap:

http://www.ebay.com/itm/Tektronix-TDS350-1GS-S-200MHz-Scope-with-Printer-
and-Com-Options-/150875129110?pt=BI_Oscilloscopes&hash=item2320dbc516

No relation to the seller.

The TDS scopes are a joy to use.

--Winston

 

[Bob Engelhardt]

Winston wrote:

On Fri, 10 Aug 2012 14:45:11 -0700, Daniel Pitts wrote:

... fairly tight budget, ...a cheap oscilloscope that is "good enough" for
hobby work. ... cheap but reliable?

For what it does, this is Dirt Cheap:

http://www.ebay.com/itm/Tektronix-TDS350-1GS-S-200MHz-Scope-with-Printer-
and-Com-Options-/150875129110?pt=BI_Oscilloscopes&hash=item2320dbc516

I'm guessing that "what it does" (e.g., Ghz sampling) is way beyond
Daniel's "good enough". And that $300 is quite a bit beyond his idea of
"cheap". But who am I to put words on the OP's mouth.

Maybe a 100Mhz, 2 ch older Tek, no more than $150.

 

[Winston]

On Fri, 10 Aug 2012 18:29:06 -0400, Bob Engelhardt wrote:


(...)

I'm guessing that "what it does" (e.g., Ghz sampling) is way beyond
Daniel's "good enough". And that $300 is quite a bit beyond his idea of
"cheap". But who am I to put words on the OP's mouth.

Maybe a 100Mhz, 2 ch older Tek, no more than $150.

Yup. Without numbers, it's impossible to define 'cheap'.

It is possible to pay too little for a scope, though.
I paid $50 for a couple Tek scopes, a 531 and a 551.
Getting them working was a hoot, but they were real
'space heaters' and I seldom used them.

So I bought a new Hitachi V-1100A for $1150. It's a good tool
and has served me well.

--Winston<-- That TDS 350 is still very lust-worthy, however.

 

On Fri, 10 Aug 2012 14:45:11 -0700, Daniel Pitts
<newsgroup.nospam@virtualinfinity.net> wrote:

As I get more advanced at creating circuits, I can see the benefit to
owning an Oscilloscope. I'm on a fairly tight budget, and was hoping to
get a recommendation on a cheap oscilloscope that is "good enough" for
hobby work. I've used one at school years ago, which probably had more
bells and whistles than I would ever need.

What features are essential for a hobbiest? What can I do without? Any
particular brands that are cheap but reliable?

Thanks for suggestions,
Daniel.

For hobby use with frequencies including audio and into the ultrasonic
range, this USB-based scope is one option.
Specs:
http://www.pdamusician.com/dpscope/features.html
Prices:
http://www.pdamusician.com/dpscope/buy_it.html

I'm currently using a Tektronix 2247 (4 channel) that I got for a
bargain when a local fiirm closed.

 

[Phil Allison]

"Daniel Pitts"

As I get more advanced at creating circuits, I can see the benefit to
owning an Oscilloscope. I'm on a fairly tight budget, and was hoping to
get a recommendation on a cheap oscilloscope that is "good enough" for
hobby work. I've used one at school years ago, which probably had more
bells and whistles than I would ever need.

What features are essential for a hobbiest? What can I do without? Any
particular brands that are cheap but reliable?

** This is cheap and ought to do you for a while.

http://www.ebay.com.au/itm/Tektronix-422-15mHz-Portable-Dual-Trace-Oscilloscope-Scope-/160842105349?pt=BI_Oscilloscopes&hash=item2572efc205

If you imagined buying NEW scope, then this is OK too.

I have one just like it - very easy to use.

http://www.electronickits.com/gold/CKOSCOPE10MHZ_Low_Cost_10MHZ_Oscilloscope.htm




.... Phil

 

[Bob Masta]

On Fri, 10 Aug 2012 14:45:11 -0700, Daniel Pitts
<newsgroup.nospam@virtualinfinity.net> wrote:

As I get more advanced at creating circuits, I can see the benefit to
owning an Oscilloscope. I'm on a fairly tight budget, and was hoping to
get a recommendation on a cheap oscilloscope that is "good enough" for
hobby work. I've used one at school years ago, which probably had more
bells and whistles than I would ever need.

What features are essential for a hobbiest? What can I do without? Any
particular brands that are cheap but reliable?

Thanks for suggestions,
Daniel.

Depends on what you want to do. If you are working at audio
frequencies you probably don't need a GHz-capable scope,
like you would for high-speed digital stuff.

I got by for years with an ancient 10 MHz Heathkit IO-103
that I built from a kit. It was certainly good enough for
the mostly-audio stuff that I was interested in at the time,
and "high speed" digital was only in the low MHz range.

Eventually I worked up to a 100 MHz B&K Precision 1580 (a
"bargain" at $800 back then!) and it's done everything I
needed since.

Now, I'd go with other's recommendations for a decent used
scope.

<shameless plug> In addition to a "real" benchtop scope,
you might want to take a look at my Daqarta software that
uses your Windows sound card. The sound card limits it to
"audio" range, but these days that can be nearly 100 kHz.
HOWEVER, despite what some "premium" cards seem to imply,
sound cards don't go down to DC... so you'll still need that
benchtop scope.

But despite the bandwidth limitations, there are some
powerful features that you won't find elsewhere. The
built-in 2-channel signal generator can create just about
any signal you want, with 4 independent "streams" per
channel. Each stream can be a simple or modulated waveform.
The base waveforms are Sine, Triangle, Ramp (with
controllable slopes that can also be modulated), Square,
Pulse (monophasic or biphasic, controllable phase heights
and widths), Arbitrary (from a file you supply), Play
(complete recordings can be played at any speed, forward or
backward, modulated, etc), uniform White noise, Gaussian
noise, Pink noise, and Band-limited noise.

The modulation options include Burst (with complete control
over rise, fall, duration, lag, and cycle times, and
rise/fall shape), AM, FM, PWM for pulse waves or phase
modulation for others, or Sweeps (which can be linear or
exponential, continuous or stepped). Modulation sources can
be simple sine waves, or can use the output of other
streams. Complete setups can be saved and instantly loaded.

On the input side, besides standard waveform display Daqarta
offers Spectrum and Spectrogram modes. Advanced signal
averaging allows you to extract signals that are buried in
noise, if they are synchronous with a clean "stimulus"
signal. (Used for "evoked potentials" to measure hearing in
animals and infants, for example).

Trigger controls include the usual, plus Hysteresis to allow
you to get a stable view of a noisy trace. Delay allows you
to see events that happened up to 32Ksamples (over a half
second) before or after the trigger. Holdoff allows you to
sync to the start of a burst while ignoring events during
the burst. There is also a Generator sync, so you can (for
example) trigger on an FM modulating frequency.

There is also a built-in frequency counter with high
precision at low frequencies via reciprocal period methods.

Built-in true RMS voltmeter and SPL meters are available if
you calibrate your system.

Daqarta includes a built-in macro language, and now includes
a number of standard "mini-apps" that can be used as-is, or
as the basis for your own applications. Some that you may
be interested in are THD meter, IMD meter, Phase meter,
Chart recorder, and (for fun, mostly) Lissajous figures.

NOTE that after the 30-day/30-session free trial, the
external inputs stop working, but the outputs are not
affected... so the signal generator is yours to keep, for
FREE. (Also file analysis, etc.) So even if you don't buy
it (US$29, or $99 for the Pro version) you might want to
install it on an old laptop and keep it on your bench next
to your hardware scope, with my best wishes. Enjoy!

Best regards,



Bob Masta

DAQARTA v7.00
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, Pitch Track, Pitch-to-MIDI
FREE Signal Generator, DaqMusic generator
Science with your sound card!

 

[Daniel Pitts]

On 8/10/12 3:29 PM, Bob Engelhardt wrote:

Winston wrote:
On Fri, 10 Aug 2012 14:45:11 -0700, Daniel Pitts wrote:

... fairly tight budget, ...a cheap oscilloscope that is "good
enough" for
hobby work. ... cheap but reliable?

For what it does, this is Dirt Cheap:

http://www.ebay.com/itm/Tektronix-TDS350-1GS-S-200MHz-Scope-with-Printer-
and-Com-Options-/150875129110?pt=BI_Oscilloscopes&hash=item2320dbc516

I'm guessing that "what it does" (e.g., Ghz sampling) is way beyond
Daniel's "good enough". And that $300 is quite a bit beyond his idea of
"cheap". But who am I to put words on the OP's mouth.

Maybe a 100Mhz, 2 ch older Tek, no more than $150.

Yeah, I suppose I should have been more specific, although I really
didn't have any idea of what the ranges of Oscilloscopes were.
Something less than $250, I could buy pretty much right away. More than
that I'd have to plan for and save up, which is also fine.

As far as sampling rates, I'd be working with digital circuits running
in the 10-30MHz range mostly, so more than audio, but I have no need for
GHz.

I didn't think about the fact that I could/should look for used, but
actually for this type of equipment that makes sense to me.

Thanks,
Daniel.

 

[Tom Biasi]

On 8/11/2012 2:12 PM, Daniel Pitts wrote:

On 8/10/12 3:29 PM, Bob Engelhardt wrote:
Winston wrote:
On Fri, 10 Aug 2012 14:45:11 -0700, Daniel Pitts wrote:

... fairly tight budget, ...a cheap oscilloscope that is "good
enough" for
hobby work. ... cheap but reliable?

For what it does, this is Dirt Cheap:

http://www.ebay.com/itm/Tektronix-TDS350-1GS-S-200MHz-Scope-with-Printer-

and-Com-Options-/150875129110?pt=BI_Oscilloscopes&hash=item2320dbc516

I'm guessing that "what it does" (e.g., Ghz sampling) is way beyond
Daniel's "good enough". And that $300 is quite a bit beyond his idea of
"cheap". But who am I to put words on the OP's mouth.

Maybe a 100Mhz, 2 ch older Tek, no more than $150.

Yeah, I suppose I should have been more specific, although I really
didn't have any idea of what the ranges of Oscilloscopes were. Something
less than $250, I could buy pretty much right away. More than that I'd
have to plan for and save up, which is also fine.

As far as sampling rates, I'd be working with digital circuits running
in the 10-30MHz range mostly, so more than audio, but I have no need for
GHz.

I didn't think about the fact that I could/should look for used, but
actually for this type of equipment that makes sense to me.

Thanks,
Daniel.
The link Phil gave you is a good scope for the money, I used one for years.

Note the shipping cost is to Australia, click in USA and it's about 40
bucks.
Here is Phil's link:
http://www.ebay.com.au/itm/Tektronix-422-15mHz-Portable-Dual-Trace-Oscilloscope-Scope-/160842105349?pt=BI_Oscilloscopes&hash=item2572efc205

 

[Daniel Pitts]

On 8/11/12 3:25 AM, Phil Allison wrote:

"Daniel Pitts"

As I get more advanced at creating circuits, I can see the benefit to
owning an Oscilloscope. I'm on a fairly tight budget, and was hoping to
get a recommendation on a cheap oscilloscope that is "good enough" for
hobby work. I've used one at school years ago, which probably had more
bells and whistles than I would ever need.

What features are essential for a hobbiest? What can I do without? Any
particular brands that are cheap but reliable?


** This is cheap and ought to do you for a while.

http://www.ebay.com.au/itm/Tektronix-422-15mHz-Portable-Dual-Trace-Oscilloscope-Scope-/160842105349?pt=BI_Oscilloscopes&hash=item2572efc205
Cheap until you account for the "postage" of $180.

If you imagined buying NEW scope, then this is OK too.

I have one just like it - very easy to use.

http://www.electronickits.com/gold/CKOSCOPE10MHZ_Low_Cost_10MHZ_Oscilloscope.htm
Looks reasonable.

When an oscilloscope says 10MHZ, what exactly does that mean? Is that
the highest frequency it can reliable display?

Thanks,
Daniel.

 

[Fred Abse]

On Sat, 11 Aug 2012 11:21:22 -0700, Daniel Pitts wrote:

When an oscilloscope says 10MHZ, what exactly does that mean? Is that the
highest frequency it can reliable display?

No.

It's the frequency at which the response has fallen to 0.707 of the
response at DC. -3dB, or half power.

--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)

 

[krw@att.bizzzzzzzzzzzz]

On Sat, 11 Aug 2012 11:21:22 -0700, Daniel Pitts
<newsgroup.nospam@virtualinfinity.net> wrote:

On 8/11/12 3:25 AM, Phil Allison wrote:
"Daniel Pitts"

As I get more advanced at creating circuits, I can see the benefit to
owning an Oscilloscope. I'm on a fairly tight budget, and was hoping to
get a recommendation on a cheap oscilloscope that is "good enough" for
hobby work. I've used one at school years ago, which probably had more
bells and whistles than I would ever need.

What features are essential for a hobbiest? What can I do without? Any
particular brands that are cheap but reliable?


** This is cheap and ought to do you for a while.

http://www.ebay.com.au/itm/Tektronix-422-15mHz-Portable-Dual-Trace-Oscilloscope-Scope-/160842105349?pt=BI_Oscilloscopes&hash=item2572efc205
Cheap until you account for the "postage" of $180.

If you imagined buying NEW scope, then this is OK too.

I have one just like it - very easy to use.

http://www.electronickits.com/gold/CKOSCOPE10MHZ_Low_Cost_10MHZ_Oscilloscope.htm
Looks reasonable.

When an oscilloscope says 10MHZ, what exactly does that mean? Is that
the highest frequency it can reliable display?

It means that the vertical amplifier has a bandwidth of 10MHz. That is, a 1V
10MHz sine wave will appear as a .7V sine wave. A 1V 10MHz square wave will
look about the same. ;-)

If you're looking at digital circuits, the rule-of-thumb is that you want a
bandwidth of at least 5x the fastest signal you're likely to see. If your
logic is 20MHz, you want a bandwidth of at least 100HMz.

 

[Jon Kirwan]

On Sat, 11 Aug 2012 11:12:00 -0700, Daniel Pitts
<newsgroup.nospam@virtualinfinity.net> wrote:

snip
As far as sampling rates, I'd be working with digital circuits running
in the 10-30MHz range mostly, so more than audio, but I have no need for
GHz.
snip

So let's say "mostly" also means sometimes more than 30MHz.
Say 40MHz. So for a clean waveform you will want about 5x or
200MHz, though at your level of interest it's possible 100MHz
would be fine. For sampling, you'd need a minimum of twice
that but really it should be more than twice. So the 1GHz
sampling really isn't so shocking, as you can see. It "gets
you by", is all.

The Rigol 1102e is specified as a 100MHz scope and it samples
at 1GHz (according to the specs, again.) So you need to keep
things in some perspective. Roughly, the sample rate is about
10x the bandwidth.

By the way, the above mentioned Rigol DS1102e might be
something to consider. Do a seach and see what you find.

Oh, and check to make sure that whatever you buy comes with
probes and a manual. More probes are better. You want to have
1X and 10X probes, 2 each of the 10x at least, and maybe a
100x even.

If your budget were higher, or you get lucky, you might
consider an MSO (mixed signal.) That gives you digital data
probes along with the analog. What I have for this is an HP
54645D -- 100MHz analog, plus 2+16 digital channels (32 with
both probe cables set up.) This makes digital circuits a
breeze to view.

Jon

 

[tuinkabouter]

On 8/11/2012 8:12 PM, Daniel Pitts wrote:

On 8/10/12 3:29 PM, Bob Engelhardt wrote:
Winston wrote:
On Fri, 10 Aug 2012 14:45:11 -0700, Daniel Pitts wrote:

... fairly tight budget, ...a cheap oscilloscope that is "good
enough" for
hobby work. ... cheap but reliable?

For what it does, this is Dirt Cheap:

http://www.ebay.com/itm/Tektronix-TDS350-1GS-S-200MHz-Scope-with-Printer-

and-Com-Options-/150875129110?pt=BI_Oscilloscopes&hash=item2320dbc516

I'm guessing that "what it does" (e.g., Ghz sampling) is way beyond
Daniel's "good enough". And that $300 is quite a bit beyond his idea of
"cheap". But who am I to put words on the OP's mouth.

Maybe a 100Mhz, 2 ch older Tek, no more than $150.

Yeah, I suppose I should have been more specific, although I really
didn't have any idea of what the ranges of Oscilloscopes were. Something
less than $250, I could buy pretty much right away. More than that I'd
have to plan for and save up, which is also fine.

As far as sampling rates, I'd be working with digital circuits running
in the 10-30MHz range mostly, so more than audio, but I have no need for
GHz.

If you do only digital, than have a look at open bench logic sniffer.
http://gadgetfactory.net/logicsniffer/
16/32 channels max 200Mhz/100Mhz sampling rate.
only $50

--
pim.

 

[Phil Allison]

"Daniel Pitts"

Phil Allison wrote:
"Daniel Pitts"

As I get more advanced at creating circuits, I can see the benefit to
owning an Oscilloscope. I'm on a fairly tight budget, and was hoping to
get a recommendation on a cheap oscilloscope that is "good enough" for
hobby work. I've used one at school years ago, which probably had more
bells and whistles than I would ever need.

What features are essential for a hobbiest? What can I do without? Any
particular brands that are cheap but reliable?


** This is cheap and ought to do you for a while.

http://www.ebay.com.au/itm/Tektronix-422-15mHz-Portable-Dual-Trace-Oscilloscope-Scope-/160842105349?pt=BI_Oscilloscopes&hash=item2572efc205

Cheap until you account for the "postage" of $180.

** Well, you did not say where you live.

Nothing in your details gives a clue it is Australia.

If you imagined buying NEW scope, then this is OK too.

I have one just like it - very easy to use.

http://www.electronickits.com/gold/CKOSCOPE10MHZ_Low_Cost_10MHZ_Oscilloscope.htm
Looks reasonable.

When an oscilloscope says 10MHZ, what exactly does that mean? Is that the
highest frequency it can reliable display?

** For an ANALOGUE scope, it indicates the highest frequency where you can
still measure the amplitude with some accuracy. But crucially, it also means
the scope will display any frequency up, to that frequency, at any setting
of the time base.

IOW the scope will display the anything range from DC to 10 MHz both
simultaneously and unambiguously.

Digital scopes ( or DSOs) will not do this.


..... Phil

 

[Phil Allison]

"Bob Masta"

I got by for years with an ancient 10 MHz Heathkit IO-103
that I built from a kit. It was certainly good enough for
the mostly-audio stuff that I was interested in at the time,
and "high speed" digital was only in the low MHz range.

** It is a fallacy to imagine that a scope used mostly for "audio" only
needs to cover the audio band and a bit beyond.

The error arises from associating the abbreviation "audio " with " audio
frequency " instead of the intended meaning of ** audio equipment **.

Audio equipment, even going back decades ago, includes:

1. Amplifiers employing valves, transistors or mosfets.

2. AM and FM radio receivers.

3. Wireless microphones.

4. Digital audio and digital musical instruments.

An audio power amplifier that is working correctly will not involve
frequencies much above 100kHz - BUT a faulty amplifier may exhibit
oscillations at up to 50MHz, particularly mosfet examples. You need to be
able to see it on the scope to fix it.

FM broadcast receivers have an IF strip at 10.7 MHz that can need to be
viewed.

Wireless mic transmitters have crystal oscillators operating at 50MHz or
more that need to be checked.

An audio tech may be presented with CB radio or RC model control gear to fix
too - I have.

I use a good, dual trace 50MHz analogue scope for "audio" - and it is just
good enough.

I also own but do not use a 50MHz DSO, as I find it very unsatisfactory for
servicing or troubleshooting work.


.... Phil

 

[David Eather]

On Sat, 11 Aug 2012 23:04:26 +1000, Bob Masta <N0Spam@daqarta.com> wrote:

On Fri, 10 Aug 2012 14:45:11 -0700, Daniel Pitts
newsgroup.nospam@virtualinfinity.net> wrote:

As I get more advanced at creating circuits, I can see the benefit to
owning an Oscilloscope. I'm on a fairly tight budget, and was hoping to
get a recommendation on a cheap oscilloscope that is "good enough" for
hobby work. I've used one at school years ago, which probably had more
bells and whistles than I would ever need.

What features are essential for a hobbiest? What can I do without? Any
particular brands that are cheap but reliable?

Thanks for suggestions,
Daniel.

Depends on what you want to do. If you are working at audio
frequencies you probably don't need a GHz-capable scope,
like you would for high-speed digital stuff.

I got by for years with an ancient 10 MHz Heathkit IO-103
that I built from a kit. It was certainly good enough for
the mostly-audio stuff that I was interested in at the time,
and "high speed" digital was only in the low MHz range.

Eventually I worked up to a 100 MHz B&K Precision 1580 (a
"bargain" at $800 back then!) and it's done everything I
needed since.

Now, I'd go with other's recommendations for a decent used
scope.

shameless plug> In addition to a "real" benchtop scope,
you might want to take a look at my Daqarta software that
uses your Windows sound card. The sound card limits it to
"audio" range, but these days that can be nearly 100 kHz.
HOWEVER, despite what some "premium" cards seem to imply,
sound cards don't go down to DC... so you'll still need that
benchtop scope.

But despite the bandwidth limitations, there are some
powerful features that you won't find elsewhere. The
built-in 2-channel signal generator can create just about
any signal you want, with 4 independent "streams" per
channel. Each stream can be a simple or modulated waveform.
The base waveforms are Sine, Triangle, Ramp (with
controllable slopes that can also be modulated), Square,
Pulse (monophasic or biphasic, controllable phase heights
and widths), Arbitrary (from a file you supply), Play
(complete recordings can be played at any speed, forward or
backward, modulated, etc), uniform White noise, Gaussian
noise, Pink noise, and Band-limited noise.

The modulation options include Burst (with complete control
over rise, fall, duration, lag, and cycle times, and
rise/fall shape), AM, FM, PWM for pulse waves or phase
modulation for others, or Sweeps (which can be linear or
exponential, continuous or stepped). Modulation sources can
be simple sine waves, or can use the output of other
streams. Complete setups can be saved and instantly loaded.

On the input side, besides standard waveform display Daqarta
offers Spectrum and Spectrogram modes. Advanced signal
averaging allows you to extract signals that are buried in
noise, if they are synchronous with a clean "stimulus"
signal. (Used for "evoked potentials" to measure hearing in
animals and infants, for example).

Trigger controls include the usual, plus Hysteresis to allow
you to get a stable view of a noisy trace. Delay allows you
to see events that happened up to 32Ksamples (over a half
second) before or after the trigger. Holdoff allows you to
sync to the start of a burst while ignoring events during
the burst. There is also a Generator sync, so you can (for
example) trigger on an FM modulating frequency.

There is also a built-in frequency counter with high
precision at low frequencies via reciprocal period methods.

Built-in true RMS voltmeter and SPL meters are available if
you calibrate your system.

Daqarta includes a built-in macro language, and now includes
a number of standard "mini-apps" that can be used as-is, or
as the basis for your own applications. Some that you may
be interested in are THD meter, IMD meter, Phase meter,
Chart recorder, and (for fun, mostly) Lissajous figures.

NOTE that after the 30-day/30-session free trial, the
external inputs stop working, but the outputs are not
affected... so the signal generator is yours to keep, for
FREE. (Also file analysis, etc.) So even if you don't buy
it (US$29, or $99 for the Pro version) you might want to
install it on an old laptop and keep it on your bench next
to your hardware scope, with my best wishes. Enjoy!

Best regards,



Bob Masta
DAQARTA v7.00
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, Pitch Track, Pitch-to-MIDI
FREE Signal Generator, DaqMusic generator
Science with your sound card!

In addition to Phil's comments I would also point out that a 10MHz cro
will only display the fundamental at 10MHz, so a perfectly good 10MHz
square wave will look like a very bad 10MHz sine wave and have you chasing
non-existent faults. To display a square wave you need 5 or better yet 10
times the bandwidth. A beginning hobbyist can easily need more if they
start playing digital circuits, PICAXE or any other beginner micro. So I
would say, if the budget can stand it 20MHz or more.
--
Using Opera's revolutionary email client: http://www.opera.com/mail/

 

[Bob Masta]

On Sun, 12 Aug 2012 11:46:53 +1000, "Phil Allison"
<phil_a@tpg.com.au> wrote:

"Bob Masta"

I got by for years with an ancient 10 MHz Heathkit IO-103
that I built from a kit. It was certainly good enough for
the mostly-audio stuff that I was interested in at the time,
and "high speed" digital was only in the low MHz range.

** It is a fallacy to imagine that a scope used mostly for "audio" only
needs to cover the audio band and a bit beyond.

The error arises from associating the abbreviation "audio " with " audio
frequency " instead of the intended meaning of ** audio equipment **.

Audio equipment, even going back decades ago, includes:

1. Amplifiers employing valves, transistors or mosfets.

2. AM and FM radio receivers.

3. Wireless microphones.

4. Digital audio and digital musical instruments.

An audio power amplifier that is working correctly will not involve
frequencies much above 100kHz - BUT a faulty amplifier may exhibit
oscillations at up to 50MHz, particularly mosfet examples. You need to be
able to see it on the scope to fix it.

FM broadcast receivers have an IF strip at 10.7 MHz that can need to be
viewed.

Wireless mic transmitters have crystal oscillators operating at 50MHz or
more that need to be checked.

An audio tech may be presented with CB radio or RC model control gear to fix
too - I have.

I use a good, dual trace 50MHz analogue scope for "audio" - and it is just
good enough.

I also own but do not use a 50MHz DSO, as I find it very unsatisfactory for
servicing or troubleshooting work.

Agreed 100%! I really was just "getting by" with that 10
MHz unit... and sometimes I did encounter oscillating power
amps. The clue was a "fat" trace, from the (greatly
attenuated) HF crap riding on the signal. It was enough to
know that there was a problem, without needing to see the
exact frequency or waveform of the oscillation.

Never got much into receivers and transmitters. When I
started out there was no such thing as digital audio (at
least, not outside of lab curiosities).

Things are a bit different today!

Best regards,


Bob Masta

DAQARTA v7.00
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, Pitch Track, Pitch-to-MIDI
FREE Signal Generator, DaqMusic generator
Science with your sound card!

 

[Michael Black]

On Fri, 10 Aug 2012, Winston wrote:

On Fri, 10 Aug 2012 18:29:06 -0400, Bob Engelhardt wrote:


(...)

I'm guessing that "what it does" (e.g., Ghz sampling) is way beyond
Daniel's "good enough". And that $300 is quite a bit beyond his idea of
"cheap". But who am I to put words on the OP's mouth.

Maybe a 100Mhz, 2 ch older Tek, no more than $150.

Yup. Without numbers, it's impossible to define 'cheap'.

It is possible to pay too little for a scope, though.
I paid $50 for a couple Tek scopes, a 531 and a 551.
Getting them working was a hoot, but they were real
'space heaters' and I seldom used them.

I paid five dollars for my first oscilliscope, ac coupled, no triggered

sweep, but it got me a scope. If one can get one that cheap (or my 535?
that someone found in the hospital garbage for me), one then proceeds to
play with it, seeing what the knobs do and trying to learn as much as
possible from it.

Then when they spend "real money" they have a handle on what might be
useful for their own purposes. They learn from the experience of the free
or really cheap oscilliscope, which enables them to make a better decision
when spending the money. Asking here doesn't really change things, they
are depending on someone else to tell them "a good price" and 'what they
need".

They may find they can live without things. A really cheap scope is
likely going to be limited (or old), but they may find that the
limitations are within what they are doing right now, so it doesn't
matter.

Or they may discover they don't need a scope, so having spent that five
dollars they have learned quite a bit.

Michael

So I bought a new
Hitachi V-1100A for $1150. It's a good tool > and has served me well.

--Winston<-- That TDS 350 is still very lust-worthy, however.

 

[Daniel Pitts]

On 8/11/12 5:26 PM, Phil Allison wrote:

"Daniel Pitts"
Phil Allison wrote:
"Daniel Pitts"

As I get more advanced at creating circuits, I can see the benefit to
owning an Oscilloscope. I'm on a fairly tight budget, and was hoping to
get a recommendation on a cheap oscilloscope that is "good enough" for
hobby work. I've used one at school years ago, which probably had more
bells and whistles than I would ever need.

What features are essential for a hobbiest? What can I do without? Any
particular brands that are cheap but reliable?


** This is cheap and ought to do you for a while.

http://www.ebay.com.au/itm/Tektronix-422-15mHz-Portable-Dual-Trace-Oscilloscope-Scope-/160842105349?pt=BI_Oscilloscopes&hash=item2572efc205

Cheap until you account for the "postage" of $180.

** Well, you did not say where you live.

Nothing in your details gives a clue it is Australia.
Indeed, I'm not in Australia. I wasn't paying too close attention to the

words on that page, only the numbers. I am in the USA (California
specifically).

When an oscilloscope says 10MHZ, what exactly does that mean? Is that the
highest frequency it can reliable display?

** For an ANALOGUE scope, it indicates the highest frequency where you can
still measure the amplitude with some accuracy. But crucially, it also means
the scope will display any frequency up, to that frequency, at any setting
of the time base.

IOW the scope will display the anything range from DC to 10 MHz both
simultaneously and unambiguously.
Okay, but if the frequency starts to get up to (say) 30MHz, I'll end up

with aliasing? Or just a decrease in amplitude? Or both?

If I don't care about the amplitude of the signal, only the shape, is a
10MHz scope good enough for viewing higher frequencies?

Thanks,
Daniel.