OOPS! I did it again! I had a typo in the part numbers on a slide, which I then read aloud. 4:43 Correct part numbers for the low-power parts are TLV431 and TLVH431. Sorry for the confusion!
Zeners make an excellent noise generator. They are useful signal analysis and much more, going up to 2000 MHz I regularly use these bandgap diodes in new designs. They can be directly used as shunt regulators giving an extremely stable and low noise supply voltage for signal front ends. Just one resistor and a diode fitted according to the need of current
@@henrikstenlund5385 indeed! There are a couple of later videos on this channel where a TL431B appears as a shunt regulator, and as a current source with a outboard pass transistor, for exactly the reasons you mention. And the channel's very first video is about a noise source that, rather than using a packaged Zener, uses the B-E junction of a BJT in avalanche conduction - essentially the same thing as a Zener.
@@KludgesFromKevinsCave Yes, you just reminded me of the very old trick of using an npn in an incorrect polarity and current limited. It becomes a strong noise source and the junction transforms to a zener. Many years ago wanted to see what is happening inside the npn metal cans. Some of them sent out white light like a weak LED. Thank you for sharing.
Very COoL. Thank you for the Deep-Dive (I was just barely hanging on but loved every minute). A very sub-worthy video :) I'll spread the word that I finally saw a real "Caveman". Cheers from So.Ca.USA 3rd house on the left (please call ahead before stopping by)
@@KludgesFromKevinsCave I saw what you did there Very punny! The flyer I read didn't say anything about a floor show.. And no "cover charge"? Simply electrifying. Live long and prosper 🖖
Great video. Thanks. Just to make your analysis easier, the transistor in the part inverts the output. You can then think of the non-inverting input terminal of the op-amp as the inverting terminal. Negative feedback is then easy to see.
@Electrotech1980 I'll most likely be taking just the sort of shortcut you mention as things move forward. Right now, I wasn't too sure that my typical viewer would see at a glance that it's a common-emitter circuit and therefore inverts the signal, so I thought it would be better to spell it out. Glad you enjoyed the video!
@SkippiiKai I have a discrete OTA in my notebook where I need a mA or so at something like four different voltages. I haven't quite worked through all the details, I might need LM385s instead. Of course there are amazing ones like AD780, at correspondingly amazing prices! The TL431 is cheap enough to just keep a few on hand.
In a recent design I did, I used one of these guys in the topology where it drives and opto-isolator to communicate from an isolated output section to the input side of a DC-DC converter. I only really wish that they were faster. They are only really good to several KHz in the typical circuit. This makes it very worthwhile to do some feedback locally on the input side if you can. They are cheap enough that if you need multiple different reference voltages, it is fine to use more than one.
Yeah, Zeners are a lot faster. Interestingly enough, low-voltage Zeners usually switch faster in the reverse direction than the forward direction - particularly fast-switching ones are sold as back diodes and used as RF switches. One thing I use these for is to power CMOS op amps (often with ±3 volt supplies). The op amps are micropower and usually driving high impedance loads, so there's no need for a fancy power supply. That lets me get the advantages of the low-voltage, low-power, rail-to-rail op amps where I need them while still fitting gracefully into a ±12V system.
@@KludgesFromKevinsCave I tend to use series regulators or references in that sort of case. The analog in my current design uses Plus 9V, minus something like but not all that close to -9V and switches to a 3.3V supply near the end of the analog chain where it goes into the ADC. The +9V is a linear regulator and the -9V is a charge pump.
I think Zeners (at least the lower voltage ones) are lower noise than bandgaps generally. The TI datasheed for the TL431 shows about 10 uV p-p 0.1-10 Hz noise. While on the internet people have measured modern 6.8V zeners to be about 3 to 1 uV p-p 0.1-10 Hz noise at modest current. Personally i have measured old soviet 9V reference zeners (7.6V zener + 2 plain diodes in series), they measured 40 to 10 uV p-p 0.1-10 Hz noise..
@victorman2227 yeah, 5.6-6.8 is kind of the sweet spot for Zeners. Higher, and you get lots more noise from avalanche conduction, lower and the voltage is all over the place. The shunt regulator configuration that I show will, of course, filter a lot of the noise.
At the low end, the biggest single problem is noise, which is mostly just that my cave is electrically noisy My bench is right by the HVAC system, and I don't live that far from a 50 kW AM broadcast tower, and so on. The cheap computer under the bench also puts out a lot of hash that I haven't managed to tame yet. The fact that the current sense is measuring the emitter rather than the collector is also a little annoying. Of course, I could fix that with a Darlington, but a real tracer needs to measure floating voltages and currents. In the forthcoming unit on current mirrors, I'll breadboard a different quick-and-dirty tracer that uses differential amplifiers. Finally, using a ramp was a bad idea. The transition when the ramp switches back over finds every instability in the measuring circuits. Taming the oscillations was kind of a chore. But I wanted to show the ramp generator as an integrator application - plus, it's the basic core of a sawtooth VCO. I'd want to take care of those problems before I go chasing fractions of a percent by matching resistors. (I probably wouldn't do that by hand - 0.1% low-rempco resistors arent' that expensive any more.)
Thanks much for your work. Might help me make up for not paying close enough attention in my circuit analysis classes all those years ago. Would you consider a couple future videos on basic KiCAD usage?
@quint5544 Anything in particular you want to see? I'm by no means an expert but I manage to get the job done. I'll probably show more KiCADding once I've covered enough of the basics to want to commit circuits to EuroRack modules.
@@KludgesFromKevinsCave It's been a couple decades since I did schematic capture with any regularity. Just about anything would be greatly appreciated! As far electrical concepts go, I'm going to start over again with your transistor series and keep an eye open for anything to do with power FETs.
@quint5544 Might be a while before I get to power FET's, because right now I'm focusing on audio signal processing. But if the channel goes on long enough, who knows where it might wind up?
Do you know that tunnel diodes (which can amplify very high frequencies) share some similar part in their I-V-diagram with Zener diodes (or shorter Z-diodes)? BTW: Your ECAD looks like OrCad.
Are you saying that Zener diodes have a negative resistance region? (I'm guessing around the start of avalanche conduction.) I don't think I've heard of that. I guess that the noise you pull off a Zener or a transistor in avalanche conduction is sort of a relaxation oscillation. Or did you have something else in mind? I'm curious. You can do some pretty funky things with devices that have negative resistance somewhere on the curve. Maybe one of these months I should build an oscillator around a negative resistance device. I don't think I'm going to find an Esaki diode readily, but a 2N6028 UJT, a neon lamp, or a diac should make for some interesting behaviour. [Hmm, I just checked, and there are a lot of Russian tunnel diodes on Ebay and the surplus sites. Interesting.) The ECAD system is KiCAD, not OrCAD. It's open source, and so far it does what I need it to do.
Now that it's morning and I've had my coffee, it occurs to me that you're not talking about the tunnel diode's negative resistance, but rather its nearly constant voltage in the reverse direction, so that (when biased properly) it can rectify weak signals (a few hundred mV peak amlitude) up in the microwave region. Essentially, that's what a back diode is - a Zener with a threshold voltage of a few hundred mV. I'd forgotten that historical curiosity. The current edition of _The Art of Electronics_ doesn't even mention them. (Although there's an index entry referring back to an earlier edition! Apparently Horowitz and Hill didn't want to forget back diodes entirely!)
Please let know if acording to Forest Mims circuit you can get a variable DC From 1 to 5 volts conecting a TL431 in the ground os a 7805 Regulator .Thank you very much
Forest Mims did a lot of circuits, so I'm not sure which one you mean. You could use a TL431-based circuit to boost the ground terminal of a 7805 to make, say, a 7.5-20V supply. Unless you have a split supply available, it's not obvious to me how you'd get less than 5 V out of the 7805 - it regulates its output to 5V above its ground reference. Obviously, you could use some other voltage regulator to lower the voltage from the 7805, but I don't think that's what you were talking about. There are some interesting power supply ideas in the TL431 data sheet. But for, say, a 1.25-5 V linear power supply I'd probably just use the venerable LM317 or one of the new, lower drop-out adjustable regulators.
Just what? happened i watched the video but didn't comment! My last comment was not for this video it's for a minecraft video! Are you phase bugs on RUclips?
Sorry to go off topic a bit. There is a channel that does some great "learning" things, but he go into trouble with a design with many issues: ruclips.net/video/ZLtOBjRCh2w/видео.html The same channel di a BRILLIANT and well thought out thorough video on Mosfets: ruclips.net/video/ElTTOsj3y-Q/видео.html This young man has a bright future, so I hop he succeeds. You might want to add comments on the 40W design issues and encourage high to NOT GIVE UP!!!!!
OOPS! I did it again! I had a typo in the part numbers on a slide, which I then read aloud.
4:43 Correct part numbers for the low-power parts are TLV431 and TLVH431.
Sorry for the confusion!
Zeners make an excellent noise generator. They are useful signal analysis and much more, going up to 2000 MHz
I regularly use these bandgap diodes in new designs. They can be directly used as shunt regulators giving an extremely stable and low noise supply voltage for signal front ends. Just one resistor and a diode fitted according to the need of current
@@henrikstenlund5385 indeed! There are a couple of later videos on this channel where a TL431B appears as a shunt regulator, and as a current source with a outboard pass transistor, for exactly the reasons you mention. And the channel's very first video is about a noise source that, rather than using a packaged Zener, uses the B-E junction of a BJT in avalanche conduction - essentially the same thing as a Zener.
@@KludgesFromKevinsCave Yes, you just reminded me of the very old trick of using an npn in an incorrect polarity and current limited. It becomes a strong noise source and the junction transforms to a zener. Many years ago wanted to see what is happening inside the npn metal cans. Some of them sent out white light like a weak LED. Thank you for sharing.
Thank you for your kind and interesting work. It is delightful to watch.
@maximebezanilla692 Glad you enjoy it!
Very COoL. Thank you for the Deep-Dive (I was just barely hanging on but loved every minute). A very sub-worthy video :) I'll spread the word that I finally saw a real "Caveman". Cheers from So.Ca.USA 3rd house on the left (please call ahead before stopping by)
@@ovalwingnut After all, what is silicon but very specialized rock? And then the audio synthesis series is all about rock music!
@@KludgesFromKevinsCave I saw what you did there Very punny! The flyer I read didn't say anything about a floor show.. And no "cover charge"? Simply electrifying. Live long and prosper 🖖
Thanks for your video on the TL431 - it's a component I've always wondered about. Now I feel more confident in using it.
Glad I could help!
Great video. Thanks. Just to make your analysis easier, the transistor in the part inverts the output. You can then think of the non-inverting input terminal of the op-amp as the inverting terminal. Negative feedback is then easy to see.
@Electrotech1980 I'll most likely be taking just the sort of shortcut you mention as things move forward. Right now, I wasn't too sure that my typical viewer would see at a glance that it's a common-emitter circuit and therefore inverts the signal, so I thought it would be better to spell it out.
Glad you enjoyed the video!
I love TL431s, too. Super simple constant current sources and sinks, and they can handle 100mA all by themselves without a pass transistor.
@SkippiiKai I have a discrete OTA in my notebook where I need a mA or so at something like four different voltages. I haven't quite worked through all the details, I might need LM385s instead.
Of course there are amazing ones like AD780, at correspondingly amazing prices! The TL431 is cheap enough to just keep a few on hand.
In a recent design I did, I used one of these guys in the topology where it drives and opto-isolator to communicate from an isolated output section to the input side of a DC-DC converter. I only really wish that they were faster. They are only really good to several KHz in the typical circuit. This makes it very worthwhile to do some feedback locally on the input side if you can.
They are cheap enough that if you need multiple different reference voltages, it is fine to use more than one.
Yeah, Zeners are a lot faster. Interestingly enough, low-voltage Zeners usually switch faster in the reverse direction than the forward direction - particularly fast-switching ones are sold as back diodes and used as RF switches.
One thing I use these for is to power CMOS op amps (often with ±3 volt supplies). The op amps are micropower and usually driving high impedance loads, so there's no need for a fancy power supply. That lets me get the advantages of the low-voltage, low-power, rail-to-rail op amps where I need them while still fitting gracefully into a ±12V system.
@@KludgesFromKevinsCave I tend to use series regulators or references in that sort of case. The analog in my current design uses Plus 9V, minus something like but not all that close to -9V and switches to a 3.3V supply near the end of the analog chain where it goes into the ADC. The +9V is a linear regulator and the -9V is a charge pump.
@kensmith5694 Yup. There's more than one way to do it.
I think Zeners (at least the lower voltage ones) are lower noise than bandgaps generally. The TI datasheed for the TL431 shows about 10 uV p-p 0.1-10 Hz noise. While on the internet people have measured modern 6.8V zeners to be about 3 to 1 uV p-p 0.1-10 Hz noise at modest current. Personally i have measured old soviet 9V reference zeners (7.6V zener + 2 plain diodes in series), they measured 40 to 10 uV p-p 0.1-10 Hz noise..
@victorman2227 yeah, 5.6-6.8 is kind of the sweet spot for Zeners. Higher, and you get lots more noise from avalanche conduction, lower and the voltage is all over the place. The shunt regulator configuration that I show will, of course, filter a lot of the noise.
Do you think that measuring the resistor values would have led to some improvements?
At the low end, the biggest single problem is noise, which is mostly just that my cave is electrically noisy My bench is right by the HVAC system, and I don't live that far from a 50 kW AM broadcast tower, and so on. The cheap computer under the bench also puts out a lot of hash that I haven't managed to tame yet.
The fact that the current sense is measuring the emitter rather than the collector is also a little annoying. Of course, I could fix that with a Darlington, but a real tracer needs to measure floating voltages and currents. In the forthcoming unit on current mirrors, I'll breadboard a different quick-and-dirty tracer that uses differential amplifiers.
Finally, using a ramp was a bad idea. The transition when the ramp switches back over finds every instability in the measuring circuits. Taming the oscillations was kind of a chore. But I wanted to show the ramp generator as an integrator application - plus, it's the basic core of a sawtooth VCO.
I'd want to take care of those problems before I go chasing fractions of a percent by matching resistors. (I probably wouldn't do that by hand - 0.1% low-rempco resistors arent' that expensive any more.)
Thanks much for your work. Might help me make up for not paying close enough attention in my circuit analysis classes all those years ago.
Would you consider a couple future videos on basic KiCAD usage?
@quint5544 Anything in particular you want to see? I'm by no means an expert but I manage to get the job done.
I'll probably show more KiCADding once I've covered enough of the basics to want to commit circuits to EuroRack modules.
@@KludgesFromKevinsCave It's been a couple decades since I did schematic capture with any regularity. Just about anything would be greatly appreciated! As far electrical concepts go, I'm going to start over again with your transistor series and keep an eye open for anything to do with power FETs.
@quint5544 Might be a while before I get to power FET's, because right now I'm focusing on audio signal processing. But if the channel goes on long enough, who knows where it might wind up?
Do you know that tunnel diodes (which can amplify very high frequencies) share some similar part in their I-V-diagram with Zener diodes (or shorter Z-diodes)? BTW: Your ECAD looks like OrCad.
Are you saying that Zener diodes have a negative resistance region? (I'm guessing around the start of avalanche conduction.) I don't think I've heard of that. I guess that the noise you pull off a Zener or a transistor in avalanche conduction is sort of a relaxation oscillation. Or did you have something else in mind? I'm curious.
You can do some pretty funky things with devices that have negative resistance somewhere on the curve. Maybe one of these months I should build an oscillator around a negative resistance device. I don't think I'm going to find an Esaki diode readily, but a 2N6028 UJT, a neon lamp, or a diac should make for some interesting behaviour.
[Hmm, I just checked, and there are a lot of Russian tunnel diodes on Ebay and the surplus sites. Interesting.)
The ECAD system is KiCAD, not OrCAD. It's open source, and so far it does what I need it to do.
Now that it's morning and I've had my coffee, it occurs to me that you're not talking about the tunnel diode's negative resistance, but rather its nearly constant voltage in the reverse direction, so that (when biased properly) it can rectify weak signals (a few hundred mV peak amlitude) up in the microwave region. Essentially, that's what a back diode is - a Zener with a threshold voltage of a few hundred mV. I'd forgotten that historical curiosity. The current edition of _The Art of Electronics_ doesn't even mention them. (Although there's an index entry referring back to an earlier edition! Apparently Horowitz and Hill didn't want to forget back diodes entirely!)
Please let know if acording to Forest Mims circuit you can get a variable DC From 1 to 5 volts conecting a TL431 in the ground os a 7805 Regulator .Thank you very much
Forest Mims did a lot of circuits, so I'm not sure which one you mean.
You could use a TL431-based circuit to boost the ground terminal of a 7805 to make, say, a 7.5-20V supply. Unless you have a split supply available, it's not obvious to me how you'd get less than 5 V out of the 7805 - it regulates its output to 5V above its ground reference.
Obviously, you could use some other voltage regulator to lower the voltage from the 7805, but I don't think that's what you were talking about.
There are some interesting power supply ideas in the TL431 data sheet. But for, say, a 1.25-5 V linear power supply I'd probably just use the venerable LM317 or one of the new, lower drop-out adjustable regulators.
I don't think such a part "TL431HV' actually exists...
@@ivolol oops. Will add in a pinned comment. TLVH431 is what I meant.
Needed in bedrock too!
Just what? happened i watched the video but didn't comment!
My last comment was not for this video it's for a minecraft video!
Are you phase bugs on RUclips?
Sorry to go off topic a bit. There is a channel that does some great "learning" things, but he go into trouble with a design with many issues: ruclips.net/video/ZLtOBjRCh2w/видео.html
The same channel di a BRILLIANT and well thought out thorough video on Mosfets: ruclips.net/video/ElTTOsj3y-Q/видео.html
This young man has a bright future, so I hop he succeeds.
You might want to add comments on the 40W design issues and encourage high to NOT GIVE UP!!!!!