From Newsgroup: sci.electronics.design

Cursitor Doom <cd@notformail.com> wrote:

On Fri, 26 Dec 2025 07:09:09 -0800, john larkin <jl@glen--canyon.com>
wrote:

https://www.ti.com/product-category/power-management/dcdc-modules/isolated/products.html

These things are tiny, cheap, and switch at 64 MHz!!!!

So what? What's the advantage of a high switching frequency beyond a
small transformer and how bad's the spurious RF output?

Small is good. Higher frequencies are better because theyrCOre easier to filter out. Better still would be if it ran continuously, because then it would be nearly trivial to keep switching junk out of sensitive circuits.

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On Fri, 26 Dec 2025 17:51:55 +0000, Cursitor Doom <cd@notformail.com>
wrote:

On Fri, 26 Dec 2025 07:09:09 -0800, john larkin <jl@glen--canyon.com>
wrote:

https://www.ti.com/product-category/power-management/dcdc-modules/isolated/products.html

These things are tiny, cheap, and switch at 64 MHz!!!!

So what? What's the advantage of a high switching frequency beyond a
small transformer and how bad's the spurious RF output?

Small and cheap are good. Especially small.

And I can lowpass filter 64 MHz easier than 100 KHz.

ICs, especially TI ICs, are taking over formerly discete, big,
expensive functions. Micromirrors, BAW, magnetics, GaN. Fun stuff.


John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On Fri, 26 Dec 2025 10:58:10 -0800, john larkin <jl@glen--canyon.com>
wrote:

On Fri, 26 Dec 2025 17:51:55 +0000, Cursitor Doom <cd@notformail.com>
wrote:

On Fri, 26 Dec 2025 07:09:09 -0800, john larkin <jl@glen--canyon.com> >>wrote:

https://www.ti.com/product-category/power-management/dcdc-modules/isolated/products.html

These things are tiny, cheap, and switch at 64 MHz!!!!

So what? What's the advantage of a high switching frequency beyond a
small transformer and how bad's the spurious RF output?

Small and cheap are good. Especially small.

And I can lowpass filter 64 MHz easier than 100 KHz.

That's a given. But the RF background noise from switching power
supplies is giving radio amateurs a *major* headache these days. It's
the radio equivalent of the recent phenomenon of light pollution. You
might take creditable trouble over your filtering, but I can tell you
there are plenty of manufacturers elsewhere whose wares are injecting
all sorts of horrible shit into the RF landscape. If there's a ham
trying to pull through a delicate signal from a distant station at
-130dBm, all that crud becomes a serious problem and no one, it seems,
is taking it sufficiently seriously.

ICs, especially TI ICs, are taking over formerly discete, big,
expensive functions. Micromirrors, BAW, magnetics, GaN. Fun stuff.

John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On Fri, 26 Dec 2025 19:14:55 +0000, Cursitor Doom <cd@notformail.com>
wrote:

On Fri, 26 Dec 2025 10:58:10 -0800, john larkin <jl@glen--canyon.com>
wrote:

On Fri, 26 Dec 2025 17:51:55 +0000, Cursitor Doom <cd@notformail.com> >>wrote:

On Fri, 26 Dec 2025 07:09:09 -0800, john larkin <jl@glen--canyon.com> >>>wrote:

https://www.ti.com/product-category/power-management/dcdc-modules/isolated/products.html

These things are tiny, cheap, and switch at 64 MHz!!!!

So what? What's the advantage of a high switching frequency beyond a >>>small transformer and how bad's the spurious RF output?

Small and cheap are good. Especially small.

And I can lowpass filter 64 MHz easier than 100 KHz.

That's a given. But the RF background noise from switching power
supplies is giving radio amateurs a *major* headache these days. It's
the radio equivalent of the recent phenomenon of light pollution.

The TI chips are spread-spectrum and designed to pass EMI specs.

https://www.dropbox.com/scl/fi/evxgr4rw4g9kb6nh3yymn/TPS54302_spectrum.JPG?rlkey=xr0bv1oeqjrdy3iy7jwfyyb8k&raw=1

https://www.dropbox.com/scl/fi/gp7lohemcwvyu2gigplzu/TPS54302_PWM.JPG?rlkey=r2mykme4zyx8j2e6bxx83vo50&raw=1

but I have found some switchers that positively screamed.


Are kids getting into ham radio these days?

I was never interested.


You

might take creditable trouble over your filtering, but I can tell you
there are plenty of manufacturers elsewhere whose wares are injecting
all sorts of horrible shit into the RF landscape. If there's a ham
trying to pull through a delicate signal from a distant station at
-130dBm, all that crud becomes a serious problem and no one, it seems,
is taking it sufficiently seriously.

ICs, especially TI ICs, are taking over formerly discete, big,
expensive functions. Micromirrors, BAW, magnetics, GaN. Fun stuff.


John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics

John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On Fri, 26 Dec 2025 12:53:59 -0800, john larkin <jl@glen--canyon.com>
wrote:

On Fri, 26 Dec 2025 19:14:55 +0000, Cursitor Doom <cd@notformail.com>
wrote:

On Fri, 26 Dec 2025 10:58:10 -0800, john larkin <jl@glen--canyon.com> >>wrote:

On Fri, 26 Dec 2025 17:51:55 +0000, Cursitor Doom <cd@notformail.com> >>>wrote:

On Fri, 26 Dec 2025 07:09:09 -0800, john larkin <jl@glen--canyon.com> >>>>wrote:

https://www.ti.com/product-category/power-management/dcdc-modules/isolated/products.html

These things are tiny, cheap, and switch at 64 MHz!!!!

So what? What's the advantage of a high switching frequency beyond a >>>>small transformer and how bad's the spurious RF output?

Small and cheap are good. Especially small.

And I can lowpass filter 64 MHz easier than 100 KHz.

That's a given. But the RF background noise from switching power
supplies is giving radio amateurs a *major* headache these days. It's
the radio equivalent of the recent phenomenon of light pollution.

The TI chips are spread-spectrum and designed to pass EMI specs.

https://www.dropbox.com/scl/fi/evxgr4rw4g9kb6nh3yymn/TPS54302_spectrum.JPG?rlkey=xr0bv1oeqjrdy3iy7jwfyyb8k&raw=1

https://www.dropbox.com/scl/fi/gp7lohemcwvyu2gigplzu/TPS54302_PWM.JPG?rlkey=r2mykme4zyx8j2e6bxx83vo50&raw=1

but I have found some switchers that positively screamed.

Are kids getting into ham radio these days?

I don't believe so. I sometimes attend ham rallies looking for
anything you can't get from likes of Mouser and Digikey, like EHT
transformers, tubes and moving coil meters for instance. When
computers became widely available to the consumer market in the early
80s, pretty much all the kids who would have most likely discovered
ham radio and gone down that path got seduced away from the analog
world and became programmers and hardware engineers in due course.
Pity for them they didn't go into RF; could have made far more money,
plus AI's already culling programming jobs even though it's still in
its infancy.

I was never interested.

Surprising how many pro RF guys are *still* active hams who build
stuff. I can't imagine having a hobby the same as my day job. They
must be really obsessed!

You

might take creditable trouble over your filtering, but I can tell you
there are plenty of manufacturers elsewhere whose wares are injecting
all sorts of horrible shit into the RF landscape. If there's a ham
trying to pull through a delicate signal from a distant station at
-130dBm, all that crud becomes a serious problem and no one, it seems,
is taking it sufficiently seriously.

ICs, especially TI ICs, are taking over formerly discete, big,
expensive functions. Micromirrors, BAW, magnetics, GaN. Fun stuff.


John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics

John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

john larkin <jl@glen--canyon.com> wrote:

On Fri, 26 Dec 2025 19:14:55 +0000, Cursitor Doom <cd@notformail.com>
wrote:

On Fri, 26 Dec 2025 10:58:10 -0800, john larkin <jl@glen--canyon.com> >wrote:

On Fri, 26 Dec 2025 17:51:55 +0000, Cursitor Doom <cd@notformail.com> >>wrote:

On Fri, 26 Dec 2025 07:09:09 -0800, john larkin <jl@glen--canyon.com> >>>wrote:

https://www.ti.com/product-category/power-management/dcdc-modules/isol >>>>ated/products.html

These things are tiny, cheap, and switch at 64 MHz!!!!

So what? What's the advantage of a high switching frequency beyond a >>>small transformer and how bad's the spurious RF output?

Small and cheap are good. Especially small.

And I can lowpass filter 64 MHz easier than 100 KHz.

That's a given. But the RF background noise from switching power
supplies is giving radio amateurs a *major* headache these days. It's
the radio equivalent of the recent phenomenon of light pollution.

The TI chips are spread-spectrum and designed to pass EMI specs.

[...]

Exactly. The same noise power spread out over even more frequencies so
as to meet a spec but with no intention of minimising the hash.

Are kids getting into ham radio these days?

I was never interested.

Nowadays the gateway seems to be CB or PMR. Then they gradually realise
that getting a licence will enable them to use other wavebands for
longer distances - or join in contests - or experiment with different
ideas ...whatever they find most interesting. One of our local clubs
makes a point of welcoming CBers and assisting them to pass the
Foundation exam.

A couple of us 'oldies' are learning CW - one because she has friends
all over the World and finds CW is a more reliable way of contacting
them (back to the topic of QRM). I'm not entirely sure why I'm doing it
but I feel it could be useful one day - and it's good to keep learning
new things. (It also makes for much simpler home-brew transmitters.)
--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On Sat, 27 Dec 2025 11:02:55 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

john larkin <jl@glen--canyon.com> wrote:

On Fri, 26 Dec 2025 19:14:55 +0000, Cursitor Doom <cd@notformail.com>
wrote:

On Fri, 26 Dec 2025 10:58:10 -0800, john larkin <jl@glen--canyon.com>
wrote:

On Fri, 26 Dec 2025 17:51:55 +0000, Cursitor Doom <cd@notformail.com>
wrote:

On Fri, 26 Dec 2025 07:09:09 -0800, john larkin <jl@glen--canyon.com>
wrote:

https://www.ti.com/product-category/power-management/dcdc-modules/isol >> >>>>ated/products.html

These things are tiny, cheap, and switch at 64 MHz!!!!

So what? What's the advantage of a high switching frequency beyond a
small transformer and how bad's the spurious RF output?

Small and cheap are good. Especially small.

And I can lowpass filter 64 MHz easier than 100 KHz.

That's a given. But the RF background noise from switching power
supplies is giving radio amateurs a *major* headache these days. It's
the radio equivalent of the recent phenomenon of light pollution.

The TI chips are spread-spectrum and designed to pass EMI specs.

[...]

Exactly. The same noise power spread out over even more frequencies so
as to meet a spec but with no intention of minimising the hash.

Are kids getting into ham radio these days?

I was never interested.

Nowadays the gateway seems to be CB or PMR. Then they gradually realise
that getting a licence will enable them to use other wavebands for
longer distances - or join in contests - or experiment with different
ideas ...whatever they find most interesting. One of our local clubs
makes a point of welcoming CBers and assisting them to pass the
Foundation exam.

A couple of us 'oldies' are learning CW - one because she has friends
all over the World and finds CW is a more reliable way of contacting
them (back to the topic of QRM). I'm not entirely sure why I'm doing it
but I feel it could be useful one day - and it's good to keep learning
new things. (It also makes for much simpler home-brew transmitters.)

Mo is a speech therapist and has worked with stroke survivors who
can't talk or write but can communicate in morse code.


John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On 27/12/2025 6:14 am, Cursitor Doom wrote:

On Fri, 26 Dec 2025 10:58:10 -0800, john larkin <jl@glen--canyon.com>
wrote:

On Fri, 26 Dec 2025 17:51:55 +0000, Cursitor Doom <cd@notformail.com>
wrote:

On Fri, 26 Dec 2025 07:09:09 -0800, john larkin <jl@glen--canyon.com>
wrote:

https://www.ti.com/product-category/power-management/dcdc-modules/isolated/products.html

These things are tiny, cheap, and switch at 64 MHz!!!!

So what? What's the advantage of a high switching frequency beyond a
small transformer and how bad's the spurious RF output?

Small and cheap are good. Especially small.

And I can lowpass filter 64 MHz easier than 100 KHz.

That's a given. But the RF background noise from switching power
supplies is giving radio amateurs a *major* headache these days. It's
the radio equivalent of the recent phenomenon of light pollution. You
might take creditable trouble over your filtering, but I can tell you
there are plenty of manufacturers elsewhere whose wares are injecting
all sorts of horrible shit into the RF landscape.

There have always been noisy switching power supplies. There have also
been some relatively quiet ones.

When I put together EMI's second phased array ultrasound scanner as
clinical trials machine I made it lot lighter than the original (and the twenty pre-prodcution prototypes) by buying a quiet 5V switching power
supply for the logic (and there was a lot of logic).

My 1996 paper on a millidegree thermostat used a switching drive for the Peltier junctions, which would have been a bad idea if I hadn't gone a
lot of trouble to minimise the low frequency content of the switched
currents, and a lot more to minimise the area within which the switched currents circulated. At one point somebody got worried that it hadn't
been filtered out well enough and swapped in the much bulkier linear
current drive we'd used early in development, but didn't see any
difference at all.

Ralph Morrisons's "Grounding and Shielding Techniques in
Instrumentation" deserves a lot of the credit. I'd read the first 1967
edition as a graduate student - it's reference 94 in my Ph.D. thesis -
and I always had a copy around throughout my professional career, though
the copy on my bookshelf is the 1998 4th edition.

If there's a ham
trying to pull through a delicate signal from a distant station at
-130dBm, all that crud becomes a serious problem and no one, it seems,
is taking it sufficiently seriously.

Some people do, but nowhere near enough.

ICs, especially TI ICs, are taking over formerly discete, big,
expensive functions. Micromirrors, BAW, magnetics, GaN. Fun stuff.

TI isn't a good choice if you want carefully designed ICs - they want
the smallest, cheapest part they can sell in volume.

Analog Device and Linear Technology (until they were bought by Analog
Devices) were more interested in higher performance parts that they
could sell at higher prices.
--
Bill Sloman, Sydney

--- Synchronet 3.21a-Linux NewsLink 1.2