nando
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Post by nando on Dec 4, 2017 18:43:12 GMT
I would like to buy a secondhand oscilloscope to learn some things about elektronics and future hobby repair work. There are some oscilloscopes available (marktplaats) but what do I look for and what to avoid?
I would like something reliable. I'm not looking for a pc connected one because I don't have a pc available in my workspace.
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solderdude
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Post by solderdude on Dec 4, 2017 19:42:51 GMT
The biggest problem with old scopes is the condition of the switches and potmeters. Nothing as annoying as intermittend contacts in any of those.
Personally I would try one out before buying.
>15 MHz and would prefer at least a 2 channel scope myself for stereo repair. To look for oscillations > 50MHz
problem is to recommend ones as it is impossible to tell the condition. I would expect to buy a good one between 100 and 200 Euros.
HP, Tektronix are good ones in general. Just don't buy the very old stuff.
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nando
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Post by nando on Dec 5, 2017 9:03:19 GMT
With very old stuff you mean valve scopes?
I think I would buy from one who sell more scopes and has some knowlegde about them. Maybe it will cost a little more but for the long term it's better I think to buy a tested scope.
Features: -analogue -2 channel -time delay (?) -memory function (?)
What if F, T and V values? Frequency, Time and Volt?
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solderdude
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Post by solderdude on Dec 5, 2017 9:33:12 GMT
Yep, old tube scopes (weigh a ton as well) but also older Philips and Heathkit scopes often have switches and or potmeters that need cleaning.
There is a seller that sells more than 1 scope. Maybe a tad pricier than others but chances are at least it works properly.
Time delay can be handy. Memory function as well. Certainly when you want to take pictures of the screen or want to have a good long look at weird events that could be captured. The better scopes are 50MHz and in most cases the input voltage ranges and timebase settings will be O.K. For higher voltages 1:10 probes can be ideal.
When you intend to look at HF waveforms (S/PDIF) clock frequencies, oscillators you will have to take the input capacitance into account.
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nando
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Post by nando on Jan 1, 2018 16:12:18 GMT
I bought a Metrix ox8042 for 100 euros. This is a differential scope with probes. The scope is in very good condition, clean en working properly. Bought from a guy who knows his stuff and has a vast collection of scopes. I'm not sure what the exact advantages are of the differential design of the scope is. I know it is for safety and there are probes which make a normal scope a differential one. Has to do with measuring volt against an isolated point? The scope is 40MHz, has digital and analogue measuring and, very handy an auto-set and a reset function. www.allaboutcircuits.com/test-measurement/oscilloscopes/differential-series-ox-8042/manual/Someone took a hailgun and shot buttons on there... there's a lot to learn. But working a little with the scope it proves to be quite an user friendly machine.
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solderdude
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Post by solderdude on Jan 6, 2018 12:08:26 GMT
Looks like a nice scope. Not just a beginners level. The balanced thing is really handy when measuring balanced audio signals or bridged amplifiers. Or anywhere else where the ground is not 'common'.
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