usure, insecure on Pete Millett +/- 15 volt (opamp) PSU
A question to those who have used his +/-15 (opamp) supply for this WBA2018 build... do the LM2941 and LM2991 regulators require isolation from the heat sinks they are attached to?
BOM does not specify but Pete being so lucid in the ways of electrons, might just assume I know these things...
A question to those who have used his +/-15 (opamp) supply for this WBA2018 build... do the LM2941 and LM2991 regulators require isolation from the heat sinks they are attached to?
BOM does not specify but Pete being so lucid in the ways of electrons, might just assume I know these things...
The answers can be deduced by highly motivated people, from a quick study of the first six pages of the datasheet(s) for those voltage regulator ICs.
I have attached the first six pages of each datasheet, below. Study and deduce! Happy sleuthing! God helps those who ____(word1)_____ ____(word2)____ . . . . amazingly, Wikipedia has an encyclopedia page about this!
_
Good people, thank you for the good intention. I was asking the question of those who actually built the product so the answer could be a word or two, no trouble at allI did, of course, consult the product sheet but to a fellow like myself, it is equal parts information and obfuscation. I need more direct and specific assistance, thus my question in the form chosen
jdg123 - Being one who never passes up a teaching moment, here are some questions that are a little more focused to help you determine the answer…
1) Is the metal tab of the regulator connected to any of the pins? (Datasheet has the answer)
2) Can that pin/tab be connected to ground?
3) Is the heatsink connected to ground? (Or to anything else…, or does it float?)
4) Does the tab need to connect to anything via the heatsink? (I.E., is an insulator going to be a problem?)
1) Is the metal tab of the regulator connected to any of the pins? (Datasheet has the answer)
2) Can that pin/tab be connected to ground?
3) Is the heatsink connected to ground? (Or to anything else…, or does it float?)
4) Does the tab need to connect to anything via the heatsink? (I.E., is an insulator going to be a problem?)
A design where the device needs to make an electrical connection to the heatsink (which is connected to... what? the kneebone?) seems somewhat contrary. Or the heatsinking isn't very critical. There cannot be many of these can there?
If a device needs heatsinking then conventional wisdom would be to use thermal grease (with or without mica) or "keratherm" which are poor conductors of electricity but indicated to optimize heat transfer.
Keratherm is available at the diyaudio store.
If a device needs heatsinking then conventional wisdom would be to use thermal grease (with or without mica) or "keratherm" which are poor conductors of electricity but indicated to optimize heat transfer.
Keratherm is available at the diyaudio store.
Congrats! Be sure to inspect every last joint. Also recommend you measure with a dmm with diode mode between each leg and next pad on PCB, just to be sure. And clean all the flux. I did it like this my second time around, a great success. Dunno what exactly I did wrong the first time though... thought I did a good job, but something went wrong nonetheless. Well well, doesn’t matter now.
Btw, it sounds just bloody great. In true Pass Labs style. Nothing is hidden, bass is awesome, and highs extended. Though not the slightest hint of harshness, rather a small amount of sweetness. Extended AND sweet. Only PL does it like that... really nice. I built to spec with small output transistors and GR JFETs. Extremely stable circuit.
Regards.
Andy
Ok, cool, I like learning 😇. Center pin of both lm2941 and lm2991 are the same as the metal “tab” one is to ground the other to input respectively. If I understand the iconography the heat sink floats. This to me (I’m guessing again) along with a lack of insulators on the BOM, says to just bolt the suckers on!
I’m not at all schooled in any of this. I usually wait for you guidance 6L6
I’m not at all schooled in any of this. I usually wait for you guidance 6L6
Cool. Verify that with your meter (is there continuity from the heatsink mounting holes to ground...) and if not, then you'll know if the heatsink is floating.
Last edited:
Another success
Thank you to this group, Wayne, the man, and a kindly thank you to 6L6 for the assist/lesson. It takes a village to build a preamp 😊
It’s all build from scrapyard aluminum, it’s good to live by a recycling center 🥰
It’s pictured above my F6, in my workshop 😎
Thank you to this group, Wayne, the man, and a kindly thank you to 6L6 for the assist/lesson. It takes a village to build a preamp 😊
It’s all build from scrapyard aluminum, it’s good to live by a recycling center 🥰
It’s pictured above my F6, in my workshop 😎
Attachments
