Recent Posts

1

Projects, Designs, and Technical Stuff / Re: Heated Ferrite == Useless Ferrite

« Last post by Kleinstein on Today at 06:15:57 am »

Soft ferrites are not permanently effected by heat (unless you go to the extremes near 1000 C). They however have a relatively low curie temperature and thus don't work as long as they are hot (e.g. > 150 C). This effect is however reversible. The air gap can be a big issue - there would have been a spacer that is not much different from the glue.

In therory there could be flybacl transformers with a permanent magnet premagnetization, that could be effected by heat. However I have not seen such a thing, except for linearity correction with CRTs. So I doubt one would find it in more normal PC supply - though they would do all kind of tricks to save a few cents.

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Beginners / Re: Why are thermal jumpers so expensive?

« Last post by dietert1 on Today at 06:14:23 am »

Somewhat similar and a possible replacement could be a high resistance SMD resistor, like this: https://www.digikey.de/de/products/detail/vishay-beyschlag-draloric-bc-components/MCA1206MD1005BP100/11196602.
Price is similar, too: 33 cents in 1000s.

Regards, Dieter

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Projects, Designs, and Technical Stuff / Re: more modern version of tl494?

« Last post by 2strokeforever on Today at 05:28:47 am »

My applications will always be DC input, could be ac or dc out, usually a buck converter.

I could see it being extra complicated to make a multi KW converter cheap, compact, accurate, and efficient.

But for a one off where none of that is a concern had some extremely crude designs work well enough by simply oversizing the fets.

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Manufacturing & Assembly / Re: Source for small "potting boxes"??.....

« Last post by Smokey on Today at 05:06:01 am »

Why not order from a reputable vendor like DigiKey? “Box, potting” is a type of box you can filter for in the Boxes product subcategory.

 https://www.digikey.com/short/8ttbh7jt

I would actually very much prefer to order from a "reputable distributor".  That is always my first choose. While I appreciate the link to a digikey category, if you had gone to that link you would see that the box configuration I need isn't available.  And while there are a bunch of pages of products, once you get past the first pages the boxes cost like $10+ each.  If I wanted to spend that much money I'd have something custom injection moulded.
This is compared to a random Chinese seller, but with the thing I actually need and a cost of $0.12.

Lose the bad attitude, dude. Newsflash, I’m not clairvoyant. I have no idea what configuration you need — you posted a screenshot with 38 different sizes.

Meanwhile, your original post made it clear you hadn’t even looked at regular sources, since you didn’t even seem to know if the boxes existed as a standard product, something a cursory google search would have shown.

Hah.  All good.  I can't be in a bad mood in a world where I finally know where to buy "Negative Ion Generator Modules".

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Projects, Designs, and Technical Stuff / Re: How is a motor run capacitor sized?

« Last post by bdunham7 on Today at 05:05:08 am »

I assume these motors run only very intermittently and only for a minute.  Do you know how much current they draw?  These might work OK.

https://www.ebay.com/itm/115457681769

OTOH, if you can get the exact replacement for $30, that might be the way to go.

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RF, Microwave, Ham Radio / Re: High bandwidth FM signal generation

« Last post by coppercone2 on Today at 05:03:59 am »

guy with 6 posts asking about high power amplifiers and broadband jamming signals what can go wrong?

i like how the first post is basic ass questions made by someone that never used a amplifier before going at 100W, and the next one is about broad band random noise. "heating" in quote marks. I love that one lol. Perhaps its not really heating. What can it be doing? how did someone get into 5g research when something is "heating". does he think we are using double speak or something ? "heating" is such a point of contention with ratings of components in electronics study... it sounds like someone that has no idea WTF their doing. I commonly see components maximum ratings described as being dependent on something thats not related to heat so I will put "heating" like its some abstract complex we came up 

Must be someone from the CB radio community? but those guys would not have a problem understanding heating, after all you just drop the amp in a bucket of water to cool it down.

what a strange uncomfortable user


and before someone smarter then him thinks its a good idea, FM signals are FROWNED upon because it EATS bandwidth. I feel like a spy would like this technology if they think someone is snooping on them

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Projects, Designs, and Technical Stuff / Re: Heated Ferrite == Useless Ferrite

« Last post by amyk on Today at 04:38:53 am »

Even that link you mentioned shows that ferrites are not affected by the sort of temperatures you're using. My guess is that you are not reassembling them correctly. Even a tiny air gap will have a huge effect.

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Test Equipment / Re: Hacking the Rigol DHO800/900 Scope

« Last post by mrisco on Today at 04:38:40 am »

Neat! Can you assign a button to toggle between views?

Maybe it is possible.

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Test Equipment / Re: Hacking the Rigol DHO800/900 Scope

« Last post by ebastler on Today at 04:34:18 am »

If you want more space for waves, you can use full screen mode. 

Neat! Can you assign a button to toggle between views?

10

Test Equipment / VESA mount for Rigol HDO4000 / DHO4000

« Last post by jwise on Today at 04:28:56 am »

Hi all,

On the suggestion (?) of this forum, I got myself a DHO4404.  I find that I'm in a bit of a crunch for desk space, so over the past few days, I modeled together a VESA mount for the back of it that attaches where the battery pack that Rigol couldn't be fucked to sell us would have gone.

I've attached some photos.  If you're in the Bambu universe you can download it from MakerWorld here: https://makerworld.com/en/models/444674

Or if you're in the Prusa universe, from Printables: https://www.printables.com/model/858885-rigol-dho4000-hdo4000-vesa-mount

Or if you want to mod it for yourself, here's the onshape link: https://cad.onshape.com/documents/bfa89435db8323d375fd32a1/w/511571cd0b08c31e0ffa8b79/e/48ab0b03f2c55600799ae151

I made it out of PETG and a bunch of M4 heat stake thread inserts.  Probably PETG is the right play because the tabs are relatively thin and you want as much layer adhesion as you can get around them.  But if you have an expensive 3D printer and an expensive scope, you can make a decision for yourself as to what kind of plastic you want holding your scope off your desk :-)

I have some other cheap-ass test equipment projects that I should get to writing up.  Some day...

Regards,
joshua