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scope differential probes

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jonpaul:
Bonjour a tous, mille mercis pour le mention.

Have  used diff probes since 1970s, on diff RF/IF tuners (Sequerra) and off line SMPS: a few moments please to clarify...

The FET input wideband probes like TEK P6046 are VERY delicate electrically and mechanically.
https://w140.com/tekwiki/wiki/P6046
Their 100 MHz  BW is seldom needed. The 25V peak V restriction, difficulty to repair a blow FET input, and huge size are limitations.

For off line SMPS, bridge, the probes are designed for such use, with > 1 kV  rating and dedicated probes.

Fluke, Teledyne, Keysight, TEK,We use similar to  Yokogwa  701927

https://tmi.yokogawa.com/us/solutions/products/oscilloscopes/oscilloscope-accessories/701927-differential-probe-150-mhz1400-v/

Since 1970s we designed, debugged and consulted on many off line SMPS, PFC, EBU and seldom used these costly devices.


Use of battery operated portable scopes and   a 2 kVA 1:1 mains isolation transformer on the primary side.
eliminated the need for such probes.

Just my experience and notes...

 HAVE AN ABSOLUTELY FANTASTIC DAY

Jon

tautech:

--- Quote from: alm on October 13, 2023, 08:41:49 pm ---
--- Quote from: tautech on October 13, 2023, 08:31:09 pm ---You'd be surprised by the # that initially don't know reference leads can be detached.

--- End quote ---
Back then probes shipped without ground leads attached. So I think the number of people knowing that they could be detached was higher then ;)

--- End quote ---
Yup, that had crossed my mind however today some would get into trouble probing without a reference and we'd just have to offer more support.
Scopes are pretty hardy these days since Tek learned to place robust PCB ground planes on the TDS200 series and not have worldwide recalls for fused traces.
A few sparks or melted reference leads are lessons newbies never forget.

robint:
JP merci mille fois :phew:

Have followed the Tek Probe doc 128pp, I stopped at active probes - not going down there.
I am suitably apprised and now have the wisdom to know how little I know.  Will tackle Probe measurements soonest tout de suite :scared:

You suggested that a battery powered dso can solve many problems.  Its a pity the my Rigol DS1054z doesnt have a battery supply port (maybe its hackable?).  In the meantime its power is 17VA so it could be run from a typical PC UPS (with PE disconnected) - has anyone done this?  Also my scope is a total plastic case with only the channel i/p sockets exposed (of course care not to connect ethernet or usb cables - which I would do with Mains power around.)
Around Covid time I rigged up an sine wave 24v inverter connected to a 50 Ah Lead battery deep cycle (what a con trick)  Dont get me started on LABs blood pressure alarm!!!  In essence whatever is claimed as Ah capacity divide by 4 - that how bad they are in practice.
Anyway it was there in case of a prolonged power cut. My APC UPS would allow me say 15mins for an orderly shut down.  I could run my router and a laptop to maintain comms to the outside world for a few hours say - never yet put to the test.  But I could use this stand alone system to power my scope - ca 0.7A from a 17 Ah battery bank, so I might get a day's use say?

Is this a techie solution? |O

tautech:

--- Quote from: robint on October 13, 2023, 09:46:56 pm ---Is this a techie solution? |O

--- End quote ---
Half arsed, yes.
But it only offers 1 isolated channel from PE as all BNC's shells share a common connection.

Scope chassis and BNC's become elevated to reference lead connection potential = risky to the operator.

tggzzz:

--- Quote from: robint on October 13, 2023, 09:46:56 pm ---You suggested that a battery powered dso can solve many problems.  Its a pity the my Rigol DS1054z doesnt have a battery supply port (maybe its hackable?).  In the meantime its power is 17VA so it could be run from a typical PC UPS (with PE disconnected) - has anyone done this?  Also my scope is a total plastic case with only the channel i/p sockets exposed (of course care not to connect ethernet or usb cables - which I would do with Mains power around.)

--- End quote ---

Battery power is beneficial, but not sufficient.

Yes, people have run scopes with PE disconnected. But that's the correct answer to the wrong question.

Read the references in the page I gave you; they will help you understand the widely different classes of scopes and probes, and the reasons it is necessary for them to exist.

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