$70 100MHz (?????) 'scope

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daveejhitchins
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$70 100MHz (?????) 'scope

Post by daveejhitchins » Mon Nov 11, 2019 9:55 am

This would, probably, be ideal for fixing Beebs and Electrons - may just be good enough for the Archimedes too?? Note: Just a see-if-there-is-anything-there 'scope!

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Re: $70 100MHz (?????) 'scope

Post by Lardo Boffin » Mon Nov 11, 2019 9:58 am

Very interesting.
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Re: $70 100MHz (?????) 'scope

Post by TimoHartong » Wed Nov 27, 2019 9:20 pm

Some calculations: square waves the upper specified frequency of your scope should be 10 times. The official frequency of the Archimedes is 24 MHz so 250 MHz would be much better. Further to this, it looks more like a single channel oscilloscope which is perhaps a bit limited to do really useful work.
My personal opinion is that a scope is a nice instrument but a logic analyzer will be more useful.

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Elminster
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Re: $70 100MHz (?????) 'scope

Post by Elminster » Thu Nov 28, 2019 5:50 pm

5 times is usual quote by scope manufacturer to pickup 5th harmonic. So you would probably get a distorted but recognisable signal with 100Mhz, but 200Mhz should be fine.

60Mhz (digital signal) on my 350Mhz scope is fine.

Having watched the video for the mini scope I Don’t think 24Mhz would be realistic on it. But pretty cheap though.

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Re: $70 100MHz (?????) 'scope

Post by julie_m » Thu Nov 28, 2019 6:21 pm

The first rule of oscilloscopes: Any oscilloscope is better than no oscilloscope.

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Elminster
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Re: $70 100MHz (?????) 'scope

Post by Elminster » Thu Nov 28, 2019 6:45 pm

julie_m wrote:
Thu Nov 28, 2019 6:21 pm
The first rule of oscilloscopes: Any oscilloscope is better than no oscilloscope.
Not if the signal displayed is garbage. And you could buy a decent second hand one instead (although $70 that would be a challenge)

Edit: should be okay for beebs though

Edit2:
I did have a quick play of putting a 25Mhz square wave into a scope and then bandwidth limiting it to 20Mhz. It obviously turns it into a sine wave and doubles the rising and falling times. But that might be good enough I suppose.

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Re: $70 100MHz (?????) 'scope

Post by TimoHartong » Sat Nov 30, 2019 8:51 pm

That depends if you want to do proper diagnostics you should be able to trust your instrumentation and know how to use it

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Re: $70 100MHz (?????) 'scope

Post by 1024MAK » Sat Nov 30, 2019 9:31 pm

You should never, ever put 100% trust in your instruments or in any test gear / equipment. Even ‘good’ brands sometimes get things wrong. In the 1990s a big user of Fluke multimeters discovered that with an audio frequency pulsing DC signal, a particular model of theirs (and we are talking about a model that cost hundreds of (£) pounds) would give a different result depending on which way round you connected the test leads (polarity).

Always understand the limitations of the test equipment that you are using. ALL test equipment has limitations...

Mark

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Elminster
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Re: $70 100MHz (?????) 'scope

Post by Elminster » Sun Dec 01, 2019 11:07 am

It would be interesting, on a Beeb, to compare one of these, a logic probe and a bench scope. Not that I have time myself.

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