| Electronics > Beginners |
| measuring CFL voltage |
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| 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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