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Power/Renewable Energy/EV's / Re: Totem Pole PFC is over-hyped?
« Last post by Andy Chee on Today at 11:23:06 am »make the mains bridge diodes synchronous?....Isn’t that a totem PFC?
Otherwise I’m not picturing your proposed topology.
Recent Posts
Otherwise I’m not picturing your proposed topology.
2
Beginners / Re: PCB review and RF layout
« Last post by aliarifat794 on Today at 11:20:32 am »Position the antenna (AE1) away from other components, especially noisy digital circuits, to minimize interference.
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Manufacturing & Assembly / Re: tough sheet dielectric material?
« Last post by T3sl4co1l on Today at 11:17:52 am »Vulcanized, "hard", or "fish" paper is a very old-fashioned solution, but it is indeed still available; there's even a UL94 classification for it:
which based on my specimen from McMaster, they've formulated it pretty accurately.
Needless to say it's just cellulose (or, the "vulcanized" type is supposed to be rubberized -- there are different products under similar trade names, beware what you're actually getting!), so is class A insulation, and generally frowned upon these days.
Polyester film/sheet (Mylar(R)) is probably the most common material, often with a rubber or acrylic adhesive, for example lining the inside of desktop PSUs. Polypropylene may also be used, depending on insulation system and etc. PET is good up to over 100C, give or take grade, required strength, possible shrink rate, etc.
Polyimide (Kapton(R) is the brand name) is indeed quite strong stuff, extremely high temperature rated as well, as polymers go; but on the brittle side, which may be problematic. (There was a time when aircraft were being wired with the stuff; after a number of high-profile failures due to fatigue, abrasion and cracking, this was phased out. It looks like a lot of space hardware still uses it though, or at least as a wrap if not as direct insulation, and that's probably fine for something floating in space without any bumps after it's orbited.)
If high temperatures and working voltages are required, consider something like resin-bonded mica paper. Microwave oven transformers regularly use(d?) it, soldering irons use it (give or take the resin, or which kind), heaters use it, it's great. Brittle obviously, but at such temperatures, you are forced to compromise on toughness. Other ceramics are an option as well (porcelain, steatite, Al2O3, etc.; mostly moldable/machinable when green/unfired, but machinable e.g. Macor(R) products also exist, or, good old grinding if you must).
Other resin-bonded products; phenolic paper (cellulose based); fiberglasses with polyester, phenolic, epoxy or silicone resins; bakelite itself is still available and used for many things (phenolic resin with fillers, molded; just not with long-distance paper/textile fibers); etc. Sheets are available of course (e.g. Garolite and other brands). Downside, being rigid materials, they aren't as usable as a lining or wrapping material.
Tim
Quote
HB: slow burning on a horizontal specimen; burning rate < 76 mm/min for thickness < 3 mm or burning stops before 100 mm
which based on my specimen from McMaster, they've formulated it pretty accurately.
Needless to say it's just cellulose (or, the "vulcanized" type is supposed to be rubberized -- there are different products under similar trade names, beware what you're actually getting!), so is class A insulation, and generally frowned upon these days.
Polyester film/sheet (Mylar(R)) is probably the most common material, often with a rubber or acrylic adhesive, for example lining the inside of desktop PSUs. Polypropylene may also be used, depending on insulation system and etc. PET is good up to over 100C, give or take grade, required strength, possible shrink rate, etc.
Polyimide (Kapton(R) is the brand name) is indeed quite strong stuff, extremely high temperature rated as well, as polymers go; but on the brittle side, which may be problematic. (There was a time when aircraft were being wired with the stuff; after a number of high-profile failures due to fatigue, abrasion and cracking, this was phased out. It looks like a lot of space hardware still uses it though, or at least as a wrap if not as direct insulation, and that's probably fine for something floating in space without any bumps after it's orbited.)
If high temperatures and working voltages are required, consider something like resin-bonded mica paper. Microwave oven transformers regularly use(d?) it, soldering irons use it (give or take the resin, or which kind), heaters use it, it's great. Brittle obviously, but at such temperatures, you are forced to compromise on toughness. Other ceramics are an option as well (porcelain, steatite, Al2O3, etc.; mostly moldable/machinable when green/unfired, but machinable e.g. Macor(R) products also exist, or, good old grinding if you must).
Other resin-bonded products; phenolic paper (cellulose based); fiberglasses with polyester, phenolic, epoxy or silicone resins; bakelite itself is still available and used for many things (phenolic resin with fillers, molded; just not with long-distance paper/textile fibers); etc. Sheets are available of course (e.g. Garolite and other brands). Downside, being rigid materials, they aren't as usable as a lining or wrapping material.
Tim
4
Beginners / Re: What component is this please?
« Last post by wasedadoc on Today at 11:13:36 am »According to your test result it is a 1.6V, 3.2 microhenry inductor. But I could not find any having the same outlook. I searched here: https://www.digikey.com/en/products/filter/fixed-inductors/71No, not microHenry. Measuring device is showing mH. milliHenry.
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Microcontrollers / Re: Dim OLED Screen replacement for Agilent Keysight U1253A U1253B U1273A U1273AX
« Last post by gamalot on Today at 11:11:08 am »I found my U1173B and did a teardown and RE for it. The circuit diagram was not carefully checked and organized so it looks a bit messy, but it should be readable.
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Beginners / Re: What component is this please?
« Last post by aliarifat794 on Today at 11:10:37 am »According to your test result it is a 1.6V, 3.2 milli henry inductor. But I could not find any having the same outlook. I searched here: https://www.digikey.com/en/products/filter/fixed-inductors/71
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Buy/Sell/Wanted / Re: Usps moneysaver
« Last post by wraper on Today at 11:10:31 am »Something that accepts crypto only, no info who they are, the only contact is telegram. Certainly not dodgy and not a scam... 
The only way this could possibly be working https://www.entrepreneur.com/business-news/woman-arrested-for-60-million-usps-counterfeit-postage-scam/453513
The only way this could possibly be working https://www.entrepreneur.com/business-news/woman-arrested-for-60-million-usps-counterfeit-postage-scam/4535138
Repair / Re: Sony J30 PSU repair
« Last post by Harry_22 on Today at 11:08:42 am »Good!
Please send me the photo of "white diode".
Please try to check again the controller name seems it is not L6574D. Try to look at it from different angles to the light.
Please send me the photo of "white diode".
Please try to check again the controller name seems it is not L6574D. Try to look at it from different angles to the light.
9
Other Equipment & Products / Re: Different bases on Amscope microscope
« Last post by voltsandjolts on Today at 11:06:39 am »You may need this info at some point in the near future:
https://www.eevblog.com/forum/repair/amscope-double-boom-replacement-bearings/
https://www.eevblog.com/forum/repair/amscope-double-boom-replacement-bearings/
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Projects, Designs, and Technical Stuff / Re: Simple illuminated time display that can be driven over USB?
« Last post by Gyro on Today at 10:53:59 am »I know it's not self illuminated but the epaper display has decent contrast and it wouldn't be hard to make a nice stand with front illumination. You could probably pick up a Kindle keyboard for little money these days and constantly USB power it. Timekeeping from the web over wifi.
Just a thought anyway - rather more of an interesting conversation piece than a basic clock... https://www.instructables.com/Literary-Clock-Made-From-E-reader/
There's also a digital version for a jailbroken paperwhite (self illuminated). Make sure the firmware version can be jailbroken.... https://github.com/mattzzw/kindle-clock
Just a thought anyway - rather more of an interesting conversation piece than a basic clock... https://www.instructables.com/Literary-Clock-Made-From-E-reader/
There's also a digital version for a jailbroken paperwhite (self illuminated). Make sure the firmware version can be jailbroken.... https://github.com/mattzzw/kindle-clock