Where can one get parts these days?

Mouser Digikey

If you can't find it in one of those two places, then you don't need it.

There is a surprising variety of parts from Amazon and even WalMart.

fredag den 22. april 2022 kl. 17.02.10 UTC+2 skrev snipped-for-privacy@gmail.com:

lcsc.com

Unless you are into restoring classic (pre-1990) equipment that is...

John :-#)#

Schhh. You are destroying the last reserve

rbowman snipped-for-privacy@montana.com wrote in news: snipped-for-privacy@mid.individual.net:

"Stackpole" makes hi rel carbon comp resistors with pulse tolerant resistive media formulations.

Yeah, but the question was where to buy them.

Why melfs?

The x-chapters (H+H) have some great data on resistor overload.

A plug for the metasearch engines: octopart.com, findchips.com, oemstrade.com.

Cheers

Phil Hobbs

always hated how milf resistors roll off the board if not glued.

Pick-and-place machines don't like them either.

Silly concept.

Here's an instrument with a strange mix of melfs and normal parts.

Tabby snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@googlegroups.com:

I am sure that even a soldered milf resistor could heat up and reflow its solder and get knocked loose too.

It is easy enough to fashion the leads of an axial leaded carbon comp resositor to attach to a pair of SMD pads. I have done so, in fact. Even done so with HV feedback resistors Protruding lead ends and HV potentials do not always mix well.

We "bump soldered" a lot of parts in the HV sections of our designs. After soldering normally perform quick additions of more solder to form a bead of solder at the node. Cannot do it too slow or it wicks into the hole just as normal. Makes for a less noisy output as well. Corona isn't just a glowing halo.

snipped-for-privacy@highlandsniptechnology.com wrote in news: snipped-for-privacy@4ax.com:

Depends on the pick head used. D'Oh!

Brainless assessor. Silly assessment. Par for the course for you, Johnny.

They were to replicate the design and features of glass encapsulated, hermetically sealed components like diodes and such.

Do you design with melfs? Why?

Why?

The glass package is thermally better than epoxies (or used to be) and extremely well sealed against contaminants. Classic diode test: run ten or twenty amps through a 1N4007 until you hear a 'pow' and see smoke. Then put it on a curve tracer. It still works normally (underneath the epoxy, the package was plug-sealed glass). The epoxy is burnt and cracked, though.

MELFs dissipate more for a given footprint and can take a bigger solder fillet which holds them in place better under high vibration, particularly when the solder's weakened at high temperatures, and if potted, there's more body for the potting to hold.

They're also much prettier.

Personally, I find them easier to handle if I have to replace one because there's more to grip, but that's a trivial concern.

But they have been noticeably harder to obtain for a few years.

Q. Were MELFs originally made that way because they're essentially leaded parts without the leads? [It goes full circle - chop open a leaded dipped ceramic capacitor and you'll often find inside a surface mount part with leads soldered/welded on.]

Yup. At one point some bright outfit was selling MELFs with square end caps to prevent them from rolling around. Dunno if they're still available.

Cheers

Phil Hobbs