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equipment:oscilloscopes [2016/03/24 22:53]
tggzzz
equipment:oscilloscopes [2020/10/24 11:16] (current)
tggzzz
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-==== Oscilloscopes ==== +===== Oscilloscopes ===== 
-=== Overview ===+ 
 +Since the oscilloscope and probe become part of the circuit being tested, it is also necessary to understand //and apply// the information on the [[equipment:oscilloscopeprobes|oscilloscope probes]] page. If in doubt (especially about safety), **please ask before damaging scopes or people**. 
 + 
 +====Safety==== 
 +**Oscilloscopes can be used dangerously**, especially when connecting to anything connected to the mains voltages, and it is easy for a beginner to make a subtle mistake. **Getting it wrong can result in __loud__ noises followed by __deathly__ slience**.  
 +  * obviously **electrocution** is a potential danger, but incorrect connections can also **melt** scope probes, cause **fires**, as well as **destroying** the **scope** or **unit** being tested.  
 +  * you may be surprised how mains earths can and do cause those problems.  
 +  * internally scopes contain >**8kV**, and they can retain the charge long after the scope is switched off. 
 + 
 +Read and understand the references in the 'Formal' and 'Praxis' sections of [[https://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/|this page]], and [[http://www.tek.com/document/primer/abcs-probes|Tektronix' ABCs of Probes Primer]] pp55-56 - and apply the knowledge //before// you make a connection.  
 + 
 +Summary: 
 +  * **probe class**: choose a suitable class (EHT, HV differential, etc) probe for your measurement 
 +  * **voltage limits**, don't forget: 
 +    *  oscilloscope (including input coupling) 
 +    *  probe (including derating at high frequencies) 
 +  * **high voltages**: don't probe anything >50V without an EHT probe or an HV differential probe 
 +  * **earthed shields**: if you connect a probe shield to anything other than earth, high currents will flow since the case is earthed. If you forget that, then see [[http://www.youtube.com/watch?v=xaELqAo4kkQ|EEVblog #279 How NOT To Blow Up Your Oscilloscope!]] 
 +  * **floating measurements**: to measure voltages not earth referenced, use an HV differential probe. See [[http://info.tek.com/www-fundamentals-of-floating-measurements-and-isolated-input-oscilloscopes_ty.html|Fundamentals of Floating Measurements and Isolated Input Oscilloscopes]] 
 +  * **//never ever ever "float a scope" by disconnecting its ground lead//**, unless you also //fully// implement the mods shown in this page's footnote. **Then don't do it; use the right probe** 
 +  * **accidental shorts**: due to slipped ground leads and exposed probe tip ground, or the tip shorting adjacent tracks/pins 
 +  * **overvoltage**: a *1/*10 probe switched to *1 
 +  * **voltage not divided**: a cheap *100/*1000 probe plus scope AC coupled puts the whole mean input voltage across the scope's input capacitor, not 1/100 or 1/1000 
 +  * **50ohm resistor melting**: a scope with a 50ohm input impedance has a very limited input voltage spec 
 +  * **CRT brightness**: don't have it too bright //or// too dim: 
 +    * a bright unchanging display can cause irreversible **phosphor burn** 
 +    * leaving the spot in a single place (XY mode) can irreversibly **warp an expansion mesh** (and therefore warp the display) or overheat and **crack the CRT** 
 +    * conversely, if the brightness is left turned right down, then the tube can be destroyed by **cathode poisioning** 
 + 
 +**Do not, under any circumstances whatsoever, disconnect an earth**; the results can kill you or - worse - can kill someone else. Use the proper type of probe!  
 +(If you //really// think you need to "float a scope" see the picture in the footnote to understand the //necessary minimum//. **Then don't do it** :) ) 
 + 
 +**Do not use any of HackSpace's scope probes for measuring mains equipment and voltages**, and that includes inside SMPSs. 
 + 
 + 
 +==== General ====
 Understand how to use them safely //before// using them. Understand how to use them safely //before// using them.
  
-This page summarises our scopes in terms of their target application domains, who might use them, and where they can be stored. The "details" section lists unique benefits. From this we can choose which scopes to cull, and to see what would be interesting in the future. +This page summarises our scopes in terms of their target application domains, who might use them, and where they can be stored. The "Specific Features" section lists unique benefits. From this we can choose which scopes to cull, and to see what would be interesting in the future. 
  
-One way of categorising scopes is by how often we expect to use them, which translates into where they should be stored:+One way of categorising scopes is by how often we expect to use them, which translates into where they should be stored //(this will be updated after the move)//:
   * electronics test bench: small, robust, easy-to-use scopes for casual use and everyday tasks   * electronics test bench: small, robust, easy-to-use scopes for casual use and everyday tasks
   * accessible shelf over the electronics test bench: unique features necessary for specific tasks, but may be large or awkward   * accessible shelf over the electronics test bench: unique features necessary for specific tasks, but may be large or awkward
   * high shelf elsewhere in G11: unique but flawed, or duplicated capabilities, or used if several scopes are required simultaneously for workshops   * high shelf elsewhere in G11: unique but flawed, or duplicated capabilities, or used if several scopes are required simultaneously for workshops
-  * dispose, because poor quality or too many duplicates or slightly faulty+  * we have disposed of some scopes, because they were poor quality or we had too many duplicates or they were slightly faulty. Details have been removed from this page, but can be found via the "Old revisions" link at the top of the page
  
 Another is by target application domain likely to be found in typical HackSpace projects. There is significant overlap between categories, and there are many other application domains. Another is by target application domain likely to be found in typical HackSpace projects. There is significant overlap between categories, and there are many other application domains.
  
-Oscilloscopes are useless on their own - they also need probes to connect to the circuit. //Probes are surprisingly fragile and significantly affect your measurements// - see the [[oscilloscopeprobes|Oscilloscope Probe]] page for more information. Note than //none// of the HackSpace probes are suitable for measuring mains voltages directly.+Oscilloscopes are useless on their own - they also need probes to connect to the circuit. //Probes are surprisingly fragile and significantly affect your measurements//**see the [[oscilloscopeprobes|Oscilloscope Probe]] page for more information**. Note than **//none// of the HackSpace probes are suitable for measuring mains voltages directly**.
  
-===Safety=== 
  
-Oscilloscopes can be used dangerously, especially when connecting to anything connected to the mains voltages. **Getting it wrong can result in __loud__ noises followed by __deathly__ slience**.     Obviously **electrocution** is a potential danger, but incorrect connections can also **melt** scope probes, cause **fires**, as well as **destroying** the **scope** or **unit** being tested. You may be surprised how mains earths can and do cause those problems.  
  
-**Do not, under any circumstances whatsoever, disconnect an earth**; the results can kill you or - worse - can kill someone else. Use the proper type of probe!  +====Using Our Oscilloscopes====
- +
-Read and understand the references in the 'Formal' and 'Praxis' sections of [[https://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/|this page]] - and apply the knowledge //before// you make a connection.  +
- +
-Less seriously, if making X-Y measurements with an analogue scope (good luck with a digital scope!), do not leave a bright spot resting in a single location. It can damage the scope by burning the phosphor or, in extreme cases, localised heating can even crack the tube. Turn the brightness down or keep the spot moving.+
    
  
 | ^Test Bench ^Accessible Shelf ^High Shelf ^Dispose ^Typical spec and examples ^ | ^Test Bench ^Accessible Shelf ^High Shelf ^Dispose ^Typical spec and examples ^
 ^Audio |Kenwood CS4125 | |Metrotest OX8020 | |<100kHz, mV - audio signals, sensors | ^Audio |Kenwood CS4125 | |Metrotest OX8020 | |<100kHz, mV - audio signals, sensors |
-^Mechatronics |Kenwood CS4125 |Topward 7042 |Metrotest OX8020 |Wavetek 9020 |<10MHz, 50mV-50V, - motors, actuators, machines | +^Mechatronics |Kenwood CS4125 | |Metrotest OX8020 | |<10MHz, 50mV-50V, - motors, actuators, machines | 
-^::: |Agilent 54621 | |Hameg HM203 |Gould OS300 |::: | +^::: |Agilent 54621 | | | |::: | 
-^Digital |Agilent 54621 |Schlumberger 5602.C |Tektronix TDS340 | |%%<=%%60MHz, 500mV-5V, - well-behaved logic e.g. Arduino | +^Digital |Agilent 54621 |IsoTech ISR-1014  | |%%<=%%60MHz, 500mV-5V, - well-behaved logic e.g. Arduino | 
-^::: | |Topward 7042 | | |::: | +^::: | |Tektronix 2245 | | |::: | 
-^Signal Integrity | |Schlumberger 5602.C |Tektronix TDS340 | |>=100MHz, 500mV-5V, medium-speed logic and checking valid logic levels, e.g. generic TTL, CMOS|+^Signal Integrity | |Tektronix 2245 | | |>=100MHz, 500mV-5V, medium-speed logic and checking valid logic levels, e.g. generic TTL, CMOS
 +^::: | |IsoTech ISR-1014 | | |::: |
 ^High-speed |  -  |  -  |  -  |  -  |>=250MHz, note not MS/s! | ^High-speed |  -  |  -  |  -  |  -  |>=250MHz, note not MS/s! |
  
-=== Details ===+==== Specific Features ====
  
 Important features indicated by **emphasis**. Important features indicated by **emphasis**.
  
-== Electronics Test Bench ==+=== Location: Electronics Test Bench ===
 | ^Kenwood CS4125 ^Agilent 54621 ^ | ^Kenwood CS4125 ^Agilent 54621 ^
 ^Location |Test bench, since small and lightweight |Test bench, since small and lightweight | ^Location |Test bench, since small and lightweight |Test bench, since small and lightweight |
 ^Domain |Audio, mechatronics |Digital, mechatronics | ^Domain |Audio, mechatronics |Digital, mechatronics |
-^Specification |20MHz, **1mV/div**, analogue |60MHz, 10mV/div, digital |+^Specification |20MHz, **1mV/div**, analogue |60MHz, 10mV/div, digital, OSD |
 ^::: | |IEEE-488 interface | ^::: | |IEEE-488 interface |
 ^::: | |Waveform capture/measurements | ^::: | |Waveform capture/measurements |
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 ^    |{{ :oscilloscope:kenwood-cs4124.jpg?direct&100 |}}|{{ :oscilloscope:agilent-54621a.jpg?direct&100 |}} | ^    |{{ :oscilloscope:kenwood-cs4124.jpg?direct&100 |}}|{{ :oscilloscope:agilent-54621a.jpg?direct&100 |}} |
  
-== Accessible Shelf Above Test Bench== +=== Location: Accessible Shelf Above Test Bench=== 
-| ^Schlumberger 5602.C ^Topward 7042 +| ^IsoTech ISR-1014 ^Tektronix 2245 
-^Location |**Floor** under test bench, on end, for high speed measurement |Test bench shelf, for when Kenwood CS4215 insufficient |  +^Location |Test bench shelf|Test bench shelf, to reduce chance of accidental damage  
-^Domain |Medium speed digital, signal integrity |Digitalmechatronics +^Domain |Medium speed digital, signal integrity |Medium speed digitalsignal integrity 
-^Specification |100MHz, 10mV/divdigital |**40MHz**, 5mV/div, analogue | +^Specification |100MHz, analogue, **4 channel**, OSD |100MHz, analogue, **4 channel**, OSD 
-^::: |IEEE488 interface |**Dual timebase** +^::: |Autosetup |Autosetup 
-^::: |Waveform capture/measurements |Standard controls +^::: |Manual time/freq/voltage measurements|Manual time/freq/voltage measurements 
-^Condition |Fully functional |Excellent – **everything just works** as expected +^Condition |Fully functional|Fully functional 
-^::: |**Appalling UI** | | +^::: | |Plan on replacing X/Y mains capacitors plus electrolytics | 
-^::: |Heavybigcannot keep on high/weak shelf | | +^::: | |May need to replace calibration battery | 
-^Comments |The **highest speed scope**|**Excellent scope** | +^Comments |**First choice** fast scope |**First choice** fast scope 
-^::: | Not for casual use  |**Service and operation manual** | +^::: |Equivalent to the Tek 2245but softbutton menus slightly less suitable for casual use |Move "soft knobs" in both directionsincluding after autosetup | 
-^::: |Potential printout via IEEE-488 |Lightweight +^::: |Small size/weight |Medium size/weight 
-^::: | |See also Kenwood, Metrotest +^::: | |**OUT OF ACTION**. //Do NOT use//. An unknown person "floated" this scope by disconnecting the protective mains earth. Apart from being **lethally dangerous** [[oscilloscopes#safety|as noted above]], it may have been damaged internally. It has been PAT tested, but must be disassembled and the PSU capacitors checked and/or replaced by a person skilled in that task. 
-^USP |100MHz |Smallmedium speedeasy +^USP |Fast, 4 channels |Fast, 4 channels, excellent triggering, standard controls | 
-^    |{{ :oscilloscope:schlumberger-5602c.jpg?direct&100 |}} |{{ :oscilloscope:topward-7042.jpg?direct&100 |}} |+^   |{{ :oscilloscope:isotech-isr1014.jpg?direct&100 |}} |{{ :oscilloscope:tektronix2245.jpg?direct&100 |}}  | 
 + 
 + 
 +=== Location: High Shelf === 
 +| ^Metrotest OX8020 ^ 
 +^Location |High shelf, for when Kenwood CS4215 insufficient |  
 +^Domain |Audio, mechatronics | 
 +^Specification |20MHz, **1mV/div**, hybrid analogue/digital  
 +^::: |Dual timebase | 
 +^::: |Limited DSO features | 
 +^::: |Manual voltage and time cursors | 
 +^::: |Prints HPGL/HP-PCL to centronics/serial | 
 +^Condition |Fully functional 
 +^::: |**UI a little odd**; dim lights indicate important settings | 
 +^Comments |**On loan** from Lee Wiltshire 
 +^::: |Similar to Kenwood CS4215Topward 7042  
 +^::: |Would be best low-end scopeexcept for awkward UI | 
 +^USP |Sensitiveprinting |  
 +^    | {{ :oscilloscope:metrotest-ox8020.jpg?direct&100 |}}| 
 + 
 +=== For Disposal === 
 +Since they were either faulty or a pain to use, and we had better scopes with these features, in February 2019 we disposed of these scopes: Wavetek 9020, Gould OS300, Tek TDS340, Schlumberger 5602.C, Hameg HM203. 
 + 
 +To make more room and to reduce the equipment that needed to be moved to the new premises, in October 2020 we disposed of the Tektronix DM63 and the Topward 7042. 
 + 
 +If you want to see their features, look at an earlier revision of this page. 
 + 
 +==== Current Scope Location ==== 
 + 
 +(this will be updated after the move) 
 + 
 +{{ :equipment:oscilloscopes_a.jpg?nolink |}} 
 +{{ :equipment:oscilloscopes_b.jpg?nolink |}} 
 + 
  
 +----
  
-== High Shelf == +This was on fleabay, and indicates the __minimum__ necessary to "float scope" by disconnecting the mains earth safety wire. In other words, //don't do it!//
-| ^Tek TDS340 ^Hameg HM203 ^Metrotest OX8020 ^ +
-^Location |High shelffor occasional use |High shelf, for use during workshops |High shelf, for when Kenwood CS4215 insufficient |  +
-^Domain |Digital, signal integrity |Audio, mechatronics |Audio, mechatronics | +
-^Specification |100MHz, 1V/div, digital |20MHz, 5mV/div, analogue |20MHz, **1mV/div**, hybrid analogue/digital +
-^::: |**Display saved on floppy** | |Dual timebase | +
-^::: | | |Limited DSO features | +
-^::: | | |Manual voltage and time cursors | +
-^::: | | |Prints HPGL/HP-PCL to centronics/serial | +
-^Condition |Ch1 broken |Mainly functional, works nicely |Fully functional | +
-^::: |Ch2 only 1V/div and above |Poor or strange controls |**UI little odd**; dim lights indicate important settings | +
-^::: |Adequate UI |X-shift knob missing | | +
-^::: |Light | | | +
-^Comments |One of the **higher speed** scopes |OKunremarkable |**On loan** from Lee Wiltshire +
-^::: |**Only scope with screen capture** | |Similar to Kenwood CS4215, Topward 7042  | +
-^::: |Dispose //after// we get another 100MHz scope with screen capture. | |Would be best low-end scope, except for awkward UI | +
-^USP |Screen capture |Nothing => candidate for disposal |Sensitive, printing |  +
-^    |{{ :oscilloscope:tektronix-tds340.jpg?direct&100 |}} | {{ :oscilloscope:hameg-hm203.jpg?direct&100 |}}| {{ :oscilloscope:metrotest-ox8020.jpg?direct&100 |}}|+
  
 +{{:oscilloscope:tektronix-howToFloatAScope.jpg?direct&400  }}
  
-== For Disposal == 
-| ^ Wavetek 9020 ^Gould OS300 ^ 
-^Location |Dispose |Dispose, for use  | 
-^Domain |General, audio, mechatronics |General, audio, mechatronics | 
-^Specification |20MHz, 5mV/div, analogue |20MHz, 2mV/div, analogue | 
-^::: |Dual timebase | | 
-^Condition |Some ringing on digital transition |Some ringing on digital transition | 
-^::: |Some channel crosstalk |Some channel crosstalk | 
-^::: |Trigger on -ve slope broken |External trig broken | 
-^::: |Delayed timebase noisy | | 
-^::: |Ch1, Ch2 uncal switch noisy | | 
-^::: |Vert mode controls quirky | | 
-^::: |Poor but could be functional |Usable for simple purposes | 
-^Comments |Adequate low-end scope |Adequate low-end scope | 
-^::: |Repair required |Usable without external trig | 
-^::: | |Lightweight | 
  • equipment/oscilloscopes.1458860003
  • Last modified: 6 years ago
  • by tggzzz