simple DC DC up converter

You don't use them because they are new. You use them when they offer a better solution to the particular problem you need to solve at the time.

You need to be able to get confident that the manufacturer will keep on shipping them, but rejecting a part just because it is single sourced isn't necessarily wise.If you really need a particular part you can sometimes buy a life-time supply.

MOSFets and GaN Fets look like fairly safe choices, not that I'm too well-informed these days.

Aluminum polymers.

Times do change.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

I looked into film caps for my application, but they are huge. Energy density is low.

People have started making alpo's in higher voltages lately, up to

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

But it makes a nice change fixing components to the board with a 13mm spanner instead of peering through the mantis.

The mantis is fabulous. It's like being a bird flying over a city.

THe boards that I'm doing now have a 0.3" parts height limit. Most film caps are bigger.

I've had bad luck with surface-mount film caps too. They tend to delaminate and trap wash water.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

The reduction of epsilon_r at high E-fields in ceramic caps is similar to the reduction of mu_r at high B-fields in magnetic cores. The former leads to a reduction of capacitance at high voltage and the latter to a reduction of inductance at high current.

Jeroen Belleman

If you want to be seen as knowing what you are talking about you do need to make your references more explicit. For you, that may take an effort.

Not as much as you like to think. Anybody who refers to polymer (capacitors) and expects his readers to realise that he meant electrolytic capacitors with a polymer electroltye isn't thinking all that hard.

If you want to be seen as knowing what you are talking about you do need to make your references more explicit. For you, that may take an effort.

Not as much as you like to think. Anybody who refers to polymer (capacitors) and expects his readers to realise that he meant electrolytic capacitors with a polymer electroltye isn't thinking all that hard.

Nowadays, in 2026, people call caps "film" or "electrolytic" or "polymer" or "ceramic", mostly.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

If you won't hire Ph.D.s you may be surrounded with people who go in for sloppy thinking and even sloppier verbal expression. Try not to let it corrupt you.

If you worked in electronic design, with other people who do it, you could stay current on parts and terminology in actual use.

Of course, people do talk funny in Australia.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

The sloppy terminology in actual use at work works because the work environment adds a great deal of context. When you are posting here, there's a lot less shared context,and you do need to be more specific.

My wife was a speech scientist, and talked to a lot to phoneticians. It's no surprise that the the obituary for her I liked best was published in the international journal of phonetics by a couple of close friends.

There are a couple of Australian accents and John Local - an English phonetician - can do broad Australian better than I can. It isn't relevant to the choice of words in a discussion of electronics. In-fix swearing (abso-bloody-lutely) is popular in some Australian contexts, and some electronic engineers do use it for comic effect, but it's utterly irrelevant to the problem you exhibit here.

So use a lithium primary cell directly, with no dc/dc converter.

That's 100% efficient.

I suggested using a 40-year Tadiran, but 10 may be good enough.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

Didn’t OP say he needed bursts of 50mA at 5V ? Last time I used Tadirans (1981) they sagged badly supplying bursts of high current.

The Energizer primary Lithium AA cells do not contain a dc-dc converter. They use lithium / iron disulfide chemistry and have a nominal voltage of 2.5V. I measure them at 2.8V initially. They spend much of their life close to 2.5V. There is an internal polyswitch type protection device. The last batch I bought had a "use by" date of December 2050 and claimed a 25 year shelf life. They used to be very expensive, but prices have fallen a lot recently since the patent expired. I like them for test instruments. They do not appear to be prone to leakage and they are electrically quiet.

Yes, exactly.

I once measured the noise behavior of batteries and no matter what some say: size matters (and closely linked: current capability) page 9/12

I also measured some lab power supplies: <

cheers, Gerhard

Thanks Gerhard! Good to know.

Jeroen Belleman

We use bypass caps.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

There's a state law here that smoke detectors must include CO sensors and have 10-year lithium batteries.

In real life, the CO detectors fail in 5 years or so.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics