Electronics > Beginners
measuring CFL voltage
schmitt trigger:
Guys, guys ,guys.
Take a deep breath and slow down.
I actually worked for several years for an electronic ballast manufacturer. Universal Lightning Technologies, if you ask. I KNOW WHAT I AM TALKING ABOUT.
Very high startup voltages are only found in instant start ballasts. For a long, 75 watt, 8 feet tube, the starting voltage was at its highest 800 volts.
For preheat tubes, and specifically, for short length tubes, the startup voltage is far lower.
For a preheat, 4 feet, T12 tube the open circuit voltage was around 250 volts.
We were in the process of starting to build CFLs when I left the company so I did not have much experience with them, but they were always preheat. I have opened up many CFLs during these last years, and with the exception of some piss-poor Chinese ones, all the CFLs I have seen are not instant start but preheat ones.
What you are correct though, is that you have to use good probes which are rated for the correct voltage.
schmitt trigger:
I found this information, for an instant start ballast. Please note these are 72 inch and 96 inch tubes. Long, long tubes.
Gyro:
The great Jim Williams was a master of these sort of measurements. Go and look at LT AN65 and scroll to Appendix C.
http://www.analog.com/media/en/technical-documentation/application-notes/an65fa.pdf
Listen to the master:
--- Quote ---Figure C10 lists some recommended probes along with their characteristics. As stated in the text, almost all standard oscilloscope probes will fail3 if used for this measurement.
Note 3: That’s twice we’ve warned you nicely.
--- End quote ---
;)
edavid:
--- Quote from: Gyro on September 19, 2018, 05:40:34 pm ---The great Jim Williams was a master of these sort of measurements. Go and look at LT AN65 and scroll to Appendix C.
http://www.analog.com/media/en/technical-documentation/application-notes/an65fa.pdf
Listen to the master:
--- Quote ---Figure C10 lists some recommended probes along with their characteristics. As stated in the text, almost all standard oscilloscope probes will fail3 if used for this measurement.
Note 3: That’s twice we’ve warned you nicely.
--- End quote ---
--- End quote ---
CCFL backlight tubes and inverters are very different from CFL light bulbs. This app note and warnings are not relevant to OP's question.
wraper:
--- Quote from: schmitt trigger on September 19, 2018, 04:13:30 pm ---I found this information, for an instant start ballast. Please note these are 72 inch and 96 inch tubes. Long, long tubes.
--- End quote ---
This is not maximum that can be there and especially with bulb removed or damaged.
--- Quote ---What you are correct though, is that you have to use good probes which are rated for the correct voltage.
--- End quote ---
Something you did not mention. Therefore I criticized your suggestion. Don't forget this is a Beginner thread and op had no clue about voltages.
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