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| Blow oscilloscope measuring coil Back EMF |
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| joeqsmith:
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| AVGresponding:
https://www.eevblog.com/forum/projects/when-to-use-mov-tvs-or-gdt/ |
| ptluis:
--- Quote from: joeqsmith on August 25, 2023, 11:40:09 pm --- --- End quote --- This was the power supply I had before, and there were situations where the display blank, the ps freezes, and some reboots happened. I no longer own the PS, otherwise I would make a video and show you guys. But I was lucky and the PS never burned out. The power supply is very good but I'm sorry to say it is also not back EMF proof. |
| tautech:
--- Quote from: ptluis on August 24, 2023, 10:00:09 pm --- --- Quote from: tautech on August 24, 2023, 09:49:51 pm --- --- Quote from: ptluis on August 24, 2023, 09:05:08 pm ---I always use a flyback diode, but what I'm trying to capture is how high this EMF reach without any kind of protection on the coil. --- End quote --- To what end ? You're dealing with switched magnetics so back EMF will always be present and its level is always relative to the impedance of the return/discharge path. Place appropriate snubbers across it and move on with the rest of your design, whatever that may be. --- End quote --- I learn a new English word today "snubbers" :-+ --- End quote --- Now with more knowledge that you're working with solenoids..... Some years back when designing circuitry to momentarily switch a 24V 10A solenoid with gear I had on hand.....a whopping big free IGBT module and back EMF protection was required for its protection. It was for wireless remote release of solenoid controlled mechanical throwing arm of a claybird trap machine. After consultation with my EE mentor at the time, a reversed biased large diode and large Zener in series were used for back EMF snubbing. IIRC a 5A diode and 10W zener, maybe 12V I don't remember sorry. |
| ptluis:
--- Quote from: tautech on August 26, 2023, 09:12:01 pm --- --- Quote from: ptluis on August 24, 2023, 10:00:09 pm --- --- Quote from: tautech on August 24, 2023, 09:49:51 pm --- --- Quote from: ptluis on August 24, 2023, 09:05:08 pm ---I always use a flyback diode, but what I'm trying to capture is how high this EMF reach without any kind of protection on the coil. --- End quote --- To what end ? You're dealing with switched magnetics so back EMF will always be present and its level is always relative to the impedance of the return/discharge path. Place appropriate snubbers across it and move on with the rest of your design, whatever that may be. --- End quote --- I learn a new English word today "snubbers" :-+ --- End quote --- Now with more knowledge that you're working with solenoids..... Some years back when designing circuitry to momentarily switch a 24V 10A solenoid with gear I had on hand.....a whopping big free IGBT module and back EMF protection was required for its protection. It was for wireless remote release of solenoid controlled mechanical throwing arm of a claybird trap machine. After consultation with my EE mentor at the time, a reversed biased large diode and large Zener in series were used for back EMF snubbing. IIRC a 5A diode and 10W zener, maybe 12V I don't remember sorry. --- End quote --- The IGBT and zener approach it's interesting, I need to do some testing. I've been collecting all sorts of information about the subject and making few testing because time is short, but i think I'll figure out the best solution. Thanks |
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