Author Topic: Phase Shift measurement oscilloscope setup  (Read 756 times)

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Offline johnwater

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Phase Shift measurement oscilloscope setup
« on: February 15, 2019, 03:16:03 am »
hello
new member.
trying to learn how to identify components out of circuit if they are good or defective.
have a keysight dsox1102g scope with 2 channels, built in waveform generator.
i get a sine wave on both channels with bnc tee on wave generator output, input two cables to channel 1  and channel 2.
i don see phase knob on this unit, perhaps it is hidden in menu of another function?
i can get diagonal  line in xy mode on display,but no other lissajaus patterns with other components.
i am doing something basically wrong with setup, need some direction.
thanks
john
 

Offline rhb

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Re: Phase Shift measurement oscilloscope setup
« Reply #1 on: February 16, 2019, 01:27:02 am »
If you feed the same signal to both channels you will get a diagonal line unless you have very different lengths of coax between the input to C1 and the input to C2 from the BNC tee.

If the DSO has a setting for channel skew you can change that to generate phase shifts which will vary with frequency.

For a more general solution take a look at this:

https://pdfserv.maximintegrated.com/en/an/AN184.pdf
 

Offline NiHaoMike

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Re: Phase Shift measurement oscilloscope setup
« Reply #2 on: February 16, 2019, 02:25:01 am »
Remove the line to the second channel (keeping the first channel connected for reference), then connect an amplified speaker to the waveform generator and a microphone to the second channel. Now set the waveform generator to 20kHz or so and move the microphone around while observing the waveforms. Try to figure out how to measure the speed of sound with that setup.
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Offline German_EE

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Should you find yourself in a chronically leaking boat, energy devoted to changing vessels is likely to be more productive than energy devoted to patching leaks.

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Offline German_EE

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Re: Phase Shift measurement oscilloscope setup
« Reply #5 on: February 16, 2019, 07:32:09 pm »
None in stock and it's a 17 week lead time from the factory, apart from that it's fine, just remember that this is a PCB mount device.
Should you find yourself in a chronically leaking boat, energy devoted to changing vessels is likely to be more productive than energy devoted to patching leaks.

Warren Buffett
 

Offline NiHaoMike

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Re: Phase Shift measurement oscilloscope setup
« Reply #6 on: February 16, 2019, 09:48:16 pm »
Could also use an audio transformer supplied from the waveform generator, in order to allow testing with frequencies other than 50/60Hz.
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Offline rstofer

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Offline Gregg

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Re: Phase Shift measurement oscilloscope setup
« Reply #8 on: February 17, 2019, 10:46:44 pm »
Mattjd,
If you want to make one of the octopus testers, you don’t necessarily have to purchase a new transformer rated 6.3 volts, almost any small transformer between 3 and 8 volts will work by changing the voltage divider resistors to values appropriate for the circuit.  Thrift stores often sell used wall warts for a couple dollars and there are a lot of old school AC wall-warts around nicely packaged and easy to use. 
At very low current transformers will provide a higher voltage than the voltage at rated load.
 

Offline johnwater

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Re: Phase Shift measurement oscilloscope setup
« Reply #9 on: February 24, 2019, 04:30:08 am »
Thanks guys for the replies.
i will try to make a octopus tester, or i see one on eBay available.
is there a chart  or calculator available that would suggest the best range of voltage and frequency, and current  to start with for component testing in a powered off circuit?like say to test diode functionality,is there a way to calculate where to start with the settings of voltage,freq,etc.?
thanks

thanks
john
 


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