So I’ve apparently botched the pronunciation of “Maida” badly. 🙁
@andidubya3840
4 ай бұрын
I keep coming back to this as it's one of the best explanations of this circuit in a practical application that I know of. However MOSFET pass device that R4 needs a better explanation. Am I right in R4 drops more than 6.4v then that's current limiting?
@Edgarbopp
4 ай бұрын
Yes, that’s my understanding though I don’t think it’s really any protection from a short so it’s perhaps of limited value.
@mekuranda
4 жыл бұрын
Thanks for this one - a good friend needed my thoughts on a high voltage regulator to upgrade/repair a tube preamplifier and I don't have any experience in voltages above 100V, so I sent him your link which I suspect will suit him perfectly - great explanation - I learned a lot from this too - subscribing, so I see any new content - love the fact I can understand your really clear voice and detailed deep dive into this kind of material.
@Edgarbopp
4 жыл бұрын
That’s very nice you you to say. Hope your friend finds it helpful.
@mekuranda
4 жыл бұрын
@@Edgarbopp I have not heard back from him yet - he does a bit of work on Tube stuff in Sydney as a repair technician - I am sure once he builds one or two he will suggest this upgrade to every tube amp he has to repair. Years ago I used cascaded 317/337s to deal with higher voltages and seemed to be ultra-reliable and fantastic performance. If he gets it working on his current project he will no doubt report back to me - and in turn I will pass on his comments to you if he does not do this direct to your video post.
@A_RosnerNZ
4 жыл бұрын
Nice work and a thorough deconstruction of the circuit. I note in your final revision you used a 5mA current source to drive the 10V zener. This probably could do with better explanation - given that Zeners tend to run best at around 10-20% of their power rating. So if using (for example) 5W Zeners instead of 0.5W, your 5mA Current Source would need to be closer to 50mA. So the takeaway is, watch the current through the zeners.
@Edgarbopp
4 жыл бұрын
Adam Rosner good point. 5ma is a good place to start and every type of zener is a bit different. The specific 10v zener I’ve got regulates well at only 5ma. That’s desirable in this circuit because the more current that zener needs the more minimum current the whole circuit needs to operate. And so we’ve found another thing I should have mentioned in the video! 😂
@PatrickInCayman
2 жыл бұрын
Thank you! Exactly what I was looking for for my tube amp power regulation.
@captainmother1268
3 жыл бұрын
Actually Maida wrote an application note for NSC - this circuit appeared in the National Semiconductor Voltage Regulator handbook before then. The elephant in the room here is this circuit doesn't withstand short circuited loads without additional protection - it can be pretty fragile if not done right. Modern way is to use LT3080 for lower noise, tighter control.
@adrianvonino2574
3 жыл бұрын
Thanks for the video, really useful !
@leiferickson3183
4 жыл бұрын
Very nice video! Have you tested one of these by repeatedly shorting the output?
@Edgarbopp
4 жыл бұрын
I have shorted it but not repetitively. I have a more robust circuit I’m designing a pcb for now. I plan to torture test it. I may make a video testing it. Should be exciting. 🙂
@gilbertbergh8980
4 жыл бұрын
Great video!
@petercalum9767
3 жыл бұрын
Hi, I have a question regarding the 5 mA current source that is in the diagram. Is it a special circuit or just a suitable resistor for the current you want. Another thing is that in the event of a short circuit, the mosfet will become very hot and may be destroyed. Another youtuber (FeZ electronics) has in a similar HV supply replaced R4 with a PTC which sits on the mosfet cooling plate and shuts down the mosfet when it gets too hot. Best regards Peter
@Edgarbopp
3 жыл бұрын
It can be either. If you know your desired output a resistor is fine. If you want it to be adjustable a CCS helpful because it will keep the zener happy at various operating points. Any short circuit protections you want to try are a great idea. I know the 317 has temp protection built in so people recommend putting it on the sink with the FET. So if the FET heats up it shuts down the 317.
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