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RE: NASA Moves PRIMA Into Phase B Development

DAB — Tue, 06 Oct 2026 19:12:46 GMT

I hope they do a better job of risk management on this telescope.

After seeing all the idiot things NASA did with the Webb telescope I wanted to defund NASA.

RE: Audio-Technica U841A Microphone Teardown

jc2048 — Fri, 25 Sep 2026 09:26:21 GMT

Interesting tear-down. The transformer construction is fascinating. Would the core material just be steel, like a mains transformer, or something more exotic?

I'd say D6 and D7 were 56V zeners. The marking is somewhat different to D5 (if they'd come from the same reel on the pick-and-place machine, you'd think they would be the same).

It's very likely this microphone will run from a 48V phantom supply.

Note that, if you try it on a mixer, you may not actually see the full 48V with the mic connected. Inside the mixer, pins 2 and 3 of the XLR are commonly fed via resistors from the 48V (if you have it enabled), so it will sit down from the 48 on load - probably somewhere around the 40V mark with it taking 2mA.

The DA shape looks wrong for a cap and there's an NXP BSX384-C11 11V zener with DA marking in that style of package. But how that fits with the circuit you've drawn, I've got no idea.

You've just reminded me that a while back I bought a couple of I2S MEMs microphones to experiment with. Must get and do that now the weather is more amenable.

RE: Audio-Technica U841A Microphone Teardown

DAB — Thu, 24 Sep 2026 20:26:01 GMT

Always like a good tear down.

I have been impressed with the mems microphone technology.

RE: Audio-Technica U841A Microphone Teardown

shabaz — Thu, 24 Sep 2026 18:58:20 GMT

I desoldered the transformer briefly to measure it. The measurements of Pri and Sec inductance are very level dependent (measurements at say 10mV and at 100mV are quite different). Anyway, it's a 1:1 transformer (I applied a 1 kHz signal and measured it). Primary inductance is about 3.4H at 1 kHz (at 10 mV drive level, and a fraction higher at 100mV drive level). DC resistance is 48 ohm across primary, and 60 ohm across secondary (30 ohm to the center tap).

RE: Audio-Technica U841A Microphone Teardown

michaelkellett — Thu, 24 Sep 2026 10:37:16 GMT

I think your schematic looks plausible.

It looks as if the idea was to have a low impedance and reasonably large (in terms of power) signal to get good S/N ratio in the real world.

Power is supplied at a few via pins 2 and 3 of the socket, L1 provides RF resistance and D6 and D7 deal with voltage spikes.

The power flows through the winding on the transformer, the DC current neatly cancelling out so as not to saturate the transformer core.

Q1 buffers the signal from the mic capsule (which will contain its own FET buffer) and drives the transformer.

It's very nicely done - all bases covered, differential signal for noise rejection and lots of RF and other interference stuff like voltage surges or static discharges dealt with.

Thanks for sharing.

RE: Audio-Technica U841A Microphone Teardown

kk99 — Thu, 24 Sep 2026 04:58:38 GMT

Great teardown and analysis.

RE: Love Birds and Artwork? Try Out Fugleramme!

Qbit — Thu, 10 Sep 2026 10:13:46 GMT

Amazing product! But most of us aren`t able to hear any song of birds, else who live near woods.

RE: Sensor Array Discovers an Underground Reservoir at Old Faithful

Qbit — Sat, 05 Sep 2026 07:56:25 GMT

Awesome technique!

RE: Voyager 1 Signal Detected by Amateurs

Qbit — Fri, 28 Aug 2026 14:47:18 GMT

That’s incredible news! It's so cool to see the Dwingeloo Observatory dish picking up Voyager 1's signal out of the noise floor is a mind-blowing achievement for the team.

Thanks so much for sharing this update, Catwell!

RE: Engineers Develop Living Circuit Boards Using Bacteria That Work Like Transistors

Qbit — Wed, 26 Aug 2026 10:39:53 GMT

Building on DAB's point the real advantage here over electronics isn't speed, it's radiation hardiness and biological self-maintenance. For multi-century deep-space missions, a biological processor that feeds on basic nutrients and repairs its own logic gates could survive harsh cosmic radiation long after silicon degradation!

RE: Engineers Develop Living Circuit Boards Using Bacteria That Work Like Transistors

DAB — Wed, 26 Aug 2026 00:14:16 GMT

Could be an interesting way to send out long range probes into the solar system that will take millennia to complete.

RE: Monitoring Mains Current: Experimenting with the SCT013 Current Clamp

shabaz — Thu, 18 Jun 2026 17:35:35 GMT

I was curious about the original manufacturer of these current transformers. A family member happened to use identical ones for his work (but sourced from a known supplier), with some branding on them.

From that, the manufacturer is http://en.yhdc.com/ and they have datasheets available there for this sensor and loads of others.

They have some wide bandwidth models (e.g. 2 kHz to 500 kHz) that look interesting for other projects.

RE: Monitoring Mains Current: Experimenting with the SCT013 Current Clamp

shabaz — Wed, 17 Jun 2026 22:21:13 GMT

I tried the SCT013 with an ADC, and added the circuit I used to the blog.

Results are good, this is with the same fan as a load. I can see a stable 63 mV AC RMS being reported. This is with 12-bit measurements (but will try to improve that with averaging). The p-p value in the screenshot isn't a bug, it's not derived from the AC RMS measurement, it includes all noise captured, and it can be safely ignored.

RE: Maker Develops RAM In Backyard Shed

DAB — Thu, 30 Apr 2026 20:34:38 GMT

Crazy RAM prices are not new.

Back in 1975, we upgraded our PDP-11 with an additional 8K words of RAM at $1/word.

In the 1980's we were paying $100/1 Mbyte of RAM.

These events come every decade as people suddenly can't get enough memory.

I still remember when Microsoft said that 640Kbytes were more than any home user would need.

Now you need GIGA words of RAM at a time when the big data centers want TERA words of RAM.

It will never end.

RE: Electronics Engineer Builds a PLFM Open-Source Radar System

DAB — Thu, 23 Apr 2026 19:55:20 GMT

I remember my group testing some of the early models of these back in the 1990's.

I hope things have improved since then.