Recent Posts

1

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

« Last post by thm_w on Today at 11:15:40 pm »

https://www.polycase.com/potting-box
https://www.budind.com/series/general-use-boxes/potting-box-style-b-series-2/#group=series-products&external_dimensions_group=0&internal_dimensions=0
https://www.ionnic.com/electrical/wiring-accessories/enclosures-1118/potting-box.html

https://www.alibaba.com/product-detail/Case-for-Negative-Ion-Generator-Module_1601044423197.html
https://www.alibaba.com/product-detail/Negative-ion-Generator-Modules-Plastic-Housing_1601044289977.html

2

Projects, Designs, and Technical Stuff / Re: Arduino Stand Alone Programmer

« Last post by pqass on Today at 11:11:33 pm »

Possible.  Sure.

It shouldn't take much to modify the "Arduino as ISP" sketch. 
Just add an I²C/SPI flash memory and some buttons.
Change the serial command processor to accept options like save/read to/from flash (using Intel hex format when connected to a host) and on a button press, read from flash and program target device (when not connected to host).  You can store several programs in the flash and select any one based on which button was pressed.

3

Projects, Designs, and Technical Stuff / Re: Nichicon UPJ for switching power supplies - what's so special about these caps?

« Last post by Someone on Today at 11:11:29 pm »

LM317 is not an LDO and therefore is stable with low ESR capacitors such as MLCC.

Perhaps you'd like to support a recent design I had where an LM337 and LM317 oscillated unless the MLCC outputs had damping added. They can and do oscillate.

4

Repair / Re: Rivets/eyelets for PCB repair

« Last post by jpanhalt on Today at 11:11:07 pm »

However, the wire method doesn't work for my present use case, which is repairing damaged plated through holes in 2-sided PCBs. I need to be able to insert a component lead through the hole.

Why not use that component lead as the "wire?"  Sounds like your mind is made up, so get out your checkbook.

5

Beginners / Connector Question

« Last post by TimeBandit on Today at 11:08:11 pm »

Ok, newbie question here, but do these connectors just pull straight off? I don't want to force anything. . . .

6

Beginners / First PCB - how does it look?

« Last post by LooseJunkHater on Today at 11:06:05 pm »

PCB view (no traces on the underside):
Schematic:
Main IC: MP5035 https://www.monolithicpower.com/en/mp5035.html

Holes labelled STP* (small holes) are TestPoint_THTPad_D1.5mm_Drill0.7mm. Holes labelled BTP* (big holes) are TestPoint:TestPoint_THTPad_D3.0mm_Drill1.5mm. The trace sizes are 3mm and 0.6mm.

I purposely went with through-holes for increased durability (if I need to perform bodges/mods). I also obviously have not yet laid the ground plane yet.

Feedback? Thanks.

7

Beginners / Re: XOR gate problem with GND

« Last post by Ian.M on Today at 11:04:39 pm »

Certainly that's another way of implementing an XNOR which is all you need if the load is active low.

Before turning this into a Muntzing competition, please consider the need to maintain V_OL and the implications for fan-in and fan-out.  74x TTL had a fan-in of four in all of AND, NAND, OR, and NOR simple gates (and eight for the 7430 NAND) and a fan-out of ten.  Obviously a stacked BJT NAND is going to run into problems getting a low enough  V_OL if you try for many more inputs.

8

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

« Last post by Smokey on Today at 11:04:30 pm »

I'm looking for a good source of small potting boxes.  The kind you put your PCB in and then fill with epoxy to act as both a weather seal and a housing. 
Requirements include some sort of mounting tab to screw the thing down.

Here is an example of the configuration I'm looking for at the moment:


I would think someone would have that off the shelf.  I don't really want to have that custom made right now.
Thoughts?

9

Projects, Designs, and Technical Stuff / Re: Webench Help - 5V buck mode supply

« Last post by davegravy on Today at 11:02:59 pm »

My average current draw will be ~150mA @ 5V, whereas 0.7A is my max draw (during very low duty-cycle Rx/Tx)

I looked at the RT6224D for example, efficiency at 12V input at 150mA is only 85% whereas Webench's solution claims 97.5%

10

RF, Microwave, Ham Radio / Re: WSJT-X on Pi

« Last post by metrologist on Today at 10:58:20 pm »

Many years ago, with a Win98 laptop, I could interface with my HF rig using PSK31. I can't do that now with the latest computing tech.