Recent Posts

1

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".

2

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.

3

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?

4

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.

5

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.

6

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?

7

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

8

Manufacturing & Assembly / Re: Advice on adding missing parts to an assembled board

« Last post by Kasper on Today at 04:26:50 am »

You could make an extra layer for a custom stencil.  Copy the paste layer and add cutouts around the componets that JLC will place so the stencil won't hit them.

9

RF, Microwave, Ham Radio / Transistor tester

« Last post by scorponog on Today at 04:25:38 am »

Howdy!
Can anyone recommend a transistor tester that would work for germanium transistor's?
I was looking at the DCA-75 but those seem to be out of stock everywhere. I have a multi unit that does a limited amount of testing now but would like to get a better unit.   
TIA

10

General Technical Chat / The strange case of phase angles

« Last post by ballsystemlord on Today at 04:21:58 am »

Hello,
I was doing some practice problems in my textbook and came upon a parallel RLC circuit. I calculated the phase angle using the impedance but my value differed from the answer key.

Puzzled, I tried obtaining it from the amperage and power vectors successfully. I tried reviewing my math, but can't figure out why my impedance vector doesn't yield the same result as the amperage and power ones. Which is correct? I thought I could try and build a circuit to test this, but the fact that this is a textbook circuit makes it unrealistic so I can't make one.

Attached are images of the problem, my calculator with results, and the answer key.

So, what's the correct phase angle? Why do the impedance and amperage/power vectors differ in their angles?

Thanks!