Zener Diode vs Tube Regulation and More

I never saw and heard a teacher who explains difficult things in such an easy, clear and understandable way, Mr Carlson, Sir!! Thank you so much!!

I am 83 years old and came across your You Tube channel by accident I started in electronics when I was about 15 years old I wish you were my instructor you are a very a good instructor I I knew how things worked but never knew the theory. I love trouble trouble shooting and watching your videos has giving me a better outlook. Keep up the good work looking forward to future videos. Merrill.

Zener diodes from 4.7 to 5.6 volts are temperature stable if the correct current is used. This is because the zener and avalanche currents within the diode cancel. Zener voltages above 5.6 volts are avalanche current dominated, which means the zener voltage will increase as temperature is increased.

Thanks Mr. Carlson , you're a gifted instructor , easy to follow .

If you were my electrics teacher in college I would have probably pursued an electrical engineering degree. Your explanations are clear and easy to understand! Thanks!

Now it's "vacuum tubes work like a FET". Back in the day: "FETs work like a pentode". Another little statement that makes me feel old.

So old school tubes are more stable than solid state parts, amazing. Great job schooling us ol' hacks, thanks for teaching us all.

"Here's a curve tracer I quickly knocked up one day... with screensaver" :D

A diode that's massively overloaded becomes (momentarily) an SED (smoke emitting diode)

Mr. Carlson on the whiteboard--------time to pay attention and I might learn something. I really enjoy how you present theory, then withdraw to the lab and demonstrate what you just told us. Thanks.

Enjoyed the video. Showing my age. I've worked with gas regulators, thyratrons, klystrons, magnetrons, and traveling wave tube amplifiers during my 22 years in the Navy! The Navy is slow to change. I was still working on vacuum tube equipment when I retired in 1991 while stationed at a Mobile Technical Unit. "If it isn't broken, don't fix it" is an adage I heard numerous times.

Paul i enjoy your videos very much and I am very sorry if my reference to the compressor again I was referencing the engineering of the original flywheel not being any reflection of you or your abilities witch are both over the top thank you for your educational stuff

Very cool demo with the gas diode tube. That is incredible accuracy for sure. It makes sense those are found in the high-end instruments you mentioned.

Thanks for keeping your youtube classes online for so long.

the tube never gets under 85...amazing, and much more beautifull aswell 😆

Different technologies have their preferred voltage range. The ideal voltage for a zener is around 5.2 volts. At this voltage, they tend to have a low temperature coefficient since the avalanche and zener effects both play a role and have opposing temperature coefficients. You will also notice that zeners 5.2v and slightly above tend to exhibit a sharp regulation curve. Solid state circuits tend to work at much lower voltages than thermionic circuits so it is a case of horses for courses. If you really wanted to replace an 85v regulator tube with solid state, and retain a low temperature coefficient, you could stack a bunch of 5.2v zeners to give the necessary voltage, or use a transistor, 2 resistors and a 5.2v zener to make a programmable shunt. In NPN configuration, collector to regulated rail. Voltage divider (potentiometer or 2 resistors) on base, zener (or TL431) on emitter. When voltage divider delivers more than 6v to base, transistor starts conducting. Given the poor temperature coefficient and poor regulating curve for low voltage zeners (below 5.2v), I tend to use forward biased LEDs and rectifier diodes for lower voltages, or a programmable shunt regulator such as a TL431 which, with the addition of a couple of resistors, is a superior replacement for zeners in most applications up to 36v and cost a penny. In short, zeners are cheap, easy to use but remember they are crude and have a very narrow window of precision. If you want precision, then there are solid state tecniques other than zener diodes to perform the function. The tube voltage reference is new to me, and I am fascinated in some of these thermionic and gas tube techniques. Thank you for sharing your knowledge of these older technologies with us.

Paul, your such a nerd - but the world sure dose need you - your explanations of electronics in your vids is so engaging and simple even I can understand them. Please keep at it.

NE2 pilot light bulbs also double as VR tubes in some devices. Thus, if replacing an older NE2 power-on indicator light with an LED or a conventional filament bulb, make sure the NE2 is NOT part of the power supply circuit as a VR tube!

I am enjoying your excellent presentations, you truly do a good job. I have an EE degree and have been working in the Silicon Valley for many years, so I always smile at the subtle differences on how we articulate two words. From the US perspective, Solder is pronounced "sodder" and a Zener is pronounce "zeener". For anyone who is learning or reviewing electronics, your efforts are truly wonderful. All the very best. Cheers

When in the Army, amongst a bunch of other equipment, I fixed RT-524A/VRC transievers (completely discreet components) and there was one gas diode in there because (for reasons/what circuit I have forgotten) an unwavering voltage control was needed no matter what temperature the thing was running at.