Blow oscilloscope measuring coil Back EMF

[joeqsmith]

[AVGresponding]

https://www.eevblog.com/forum/projects/when-to-use-mov-tvs-or-gdt/

[ptluis]

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]

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.

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.

I learn a new English word today "snubbers" 

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]

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.

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.

I learn a new English word today "snubbers" 

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.

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