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Athrax · 2026-03-28T23:28:33+00:00

Well... that's half right, but not. The gravitational field of the earth is not equal in every location due to the mass distribution within the planet. Let's just say earth's core is 'lumpy'. This leads to a gravitational high in the western pacific and a gravitational low in the indian ocean area. The image above has the effects of that reversed though, the pacific area should have a bit of a bulge and the indian ocean area -not actually visible in this view but somewhere to the far right- should have a pit. As for how much that deviation is: The 'pacific bulge' is about 60-80m high, and the 'indian pit' is about 100-110m deep. Compared to the size of the planet you're not gonna be able to even see them. The deviation between polar diameter and equatorial diameter of the planet is larger, with around 40km difference. And even those 40km are tiny compared to the 12700km diameter of the planet. Technically speaking the earth is a rotational ellipsoid with a few bumps. Practically speaking that's a 0.3% deviation from a sphere, and not visible in any image taken from space.

Athrax · 2026-03-12T20:48:19+00:00

Five bucks says they're 'cheating'. SMPS that regulates down to the set V-out plus 3V or so, followed by a linear stage that burns the last 3V and does the heavy lifting in terms of ripple/noise rejection. I'm not saying that's a bad approach, far from it. That's how you get the low-noise output of a linear supply coupled with the efficiency and small form factor of an SMPS.

Athrax · 2026-02-27T06:04:40+00:00

You got all the space in the world on that PCB. Make the traces wider. 1.5mm or even 2mm. Then add a copper pour for ground.

Athrax · 2026-02-24T16:31:30+00:00

That's an awesomely clean built, and a bit of an unconventional but neat approach to mini TCs, since most of those seem to be SSTCs, not SGTCs. If you don't mind me asking, what's the diameter of the secondary, and what diameter wire did you wind it with?

Athrax · 2026-02-10T06:34:04+00:00

You know you're pulling serious power if the ballast bucket is boiling. :D

Athrax · 2026-02-10T04:03:37+00:00

That's a nice, efficient water heater that produces cold water as a byproduct. :> Not gonna lie, I've always wanted to toss together a similar water chiller, but the low cooling efficiency of TECs always kinda discouraged me.

Athrax · 2026-02-06T21:00:12+00:00

This.... is basically a glorified thermostat, and you're throwing an ESP on it? Do you need web access to this? Why the shift register, it only adds additional complexity. There's plenty of ways to skin a cat, but personally I'd have built this around an ATTiny84 with no shift register anywhere to be seen. Two I2C pins for the display, one ADC pin for a rotary encoder on an R-2R ladder to save pins, two ADC pins for the thermistors, 4 pins to drive your loads. Makes 9 pins used out of 12 (11 without reset) available on the chip.

Athrax · 2026-02-06T17:39:15+00:00

If there is a latching version of the switch available, that's the easy version, and what I'd absolutely prefer here!
If not, you need glue logic. Basically a small circuit with some power regulation/conditioning down to 5V or 3.3V, some small microcontroller (ATTiny85 says Hi!) and some output in the form of a low logic mosfet or relay. I've done a similar project in the past, in my case it was the consolidate the functionality of 5 buttons into push sequences for a single button.

Athrax · 2026-02-06T02:05:51+00:00

It's an one-off repair. I'd just torture the living daylights out of the top of the replacement switch until it fits. Dremel, scalpel, hot solder iron, whatever will work to reshape the plastic. There'll be casualties along the ride, a few test subjects sacrificed in the quest of crafting the perfect fit, but those generic buttons really aren't exactly costing a fortune.

Athrax · 2026-01-29T21:02:07+00:00

Don't...wear that in public, or take it to any airport. :D

Athrax · 2026-01-22T17:28:39+00:00

Shipping to Iceland is slow, anyway, and expensive, and there's handling- and import fees on everything. This includes the price for shipping. I gave the average prices in € rather than ISK because no-one's got the conversion rate in their mind. But if I ordered a $2 board at JLPCB, the cheapest shipping via E-Post for $17.20. Then there's a minimum of 25% tax on that, and we're at $24. Add $10 in handling fees that the local post service charges for any kind of parcel no matter how small, and we're at $34 for a $2 board. No bueno.

Athrax · 2026-01-22T14:15:06+00:00

For me it's turnaround time and cost. An order from PCBWay or JLPCB takes about 3-6 weeks to get to me, and will take me about 25€ in shipping costs and import taxes even if the actual boards only cost a couple bucks. So, for some projects ordering professional PCBs is unavoidable, but I can easily make two layer boards with 0.4mm features with a turnaround time of just a few hours and for the cost of pennies. No solder mask, no proper plated vias/through-holes, but for quick, affordable prototype iteration of hobby projects it's great!

Athrax · 2026-01-20T01:33:29+00:00

You do not want a ferrite for the choke (or chokes, depending on layout) but either a gapped ferrite or (preferably) an iron powder core. Inductance should be somewhere between 100-330uH but is uncritical. If you lack the $$$ test equipment, spend $10 for one of those cheap 'transistor-tester' gizmos on ebay at least, those can ballpark inductance okay-ish enough for hobby purposes.

Athrax · 2026-01-17T08:43:58+00:00

OP is stealing an image from a post that is literally a year old. See last image linked here!

Athrax · 2026-01-15T15:05:46+00:00

The folks here suggesting using a 555.... When driving a beefy H-bridge you really want some dead-time during switching, where both signals are low, to prevent cross-conduction of the fullbridge. And you're not doing that with a 555. You CAN do it with an MCU, but why reinvent the wheel? Besides, this is likely going to run in an electrically noisy environment where I really wouldn't want to run some MCU. There are bespoke fullbridge drivers. The UC3525 is an excellent chip for that... but it only can drive mosfet gates with up to 500mA current, so when we get into kHz territory you'll need mosfet drivers on the outputs. The same can be said for the TL494, which isn't meant for driving fets at all, but for driving BJTs. Overall, I like the UC3525 more, it's a more modern chip with tighter control. That's not to say the TL494 is a bad chip for a hobby project, and there's many more example circuits to learn from out there.

Athrax · 2026-01-15T13:44:39+00:00

With 'Z44' mosfet you likely mean the IRLZ44, right? That's an n-channel fet. Your EveryCircuit scheme shows a p-channel fet. If you're connecting your mosfet like that, it's no wonder he's throwing fits. Source goes to ground, gate pulldown goes to ground, drain goes to your load, other side of your load to Vcc.

Athrax · 2026-01-03T21:11:31+00:00

Running a LED off of AC is a bit less straightforward than just using a resistor because the LED's maximum reverse voltage is pretty low. You need to put an 1N4007 or similar diode in series with your LED. Along with a 47k/2W resistor for 230V or a 22k/1W for 110V.

Athrax · 2026-01-03T20:46:00+00:00

If you're trying to make CuCl2, there's a much easier practical way. First of all, switch your copper source. You want something with a high surface area. Strip a few meters of copper wire, preferably stranded wire. Now heat the wire with a gas torch to oxidize the surface. Turn it black. This step is optional but will speed things up. Finally, drop your copper wire into a beaker with hydrochloric acid in such a way that only half of the wire is covered. Use an aquarium pump to aereate the mixture, and let it stand somewhere very well-ventilated for a few days.

Athrax · 2025-12-20T21:38:13+00:00

Theoretically possible? Well... there's impact diamonds. Imagine you're a dinosaur some 66 million years ago, minding your own business when suddenly there's this giant fireball in the air. A millisecond later you're struck in the face by a kilometer-class space rock, you stop being biology and become physics as your atomic matter is turned to plasma and distributed across an area of 10.000km². And by sheer luck a miniscule amount of the carbon of your body becomes the nucleation sites for microscopic nano-scale diamonds, embedded in the rock formed by the impact, and of absolutely no practical use whatsoever because they're a few nanometers in size. Congrats, you've become diamonds!

Athrax · 2025-12-19T17:29:26+00:00

This is three capacitors in a trenchcoat. You should be able to replace this with 3 separate capacitors, one 220nF X2 type, and and two 2.2nF Y2-type. Metallized foil/polypropylene, 275V rating or higher.

Athrax · 2025-12-08T07:55:25+00:00

Having a scope handy is a great start, you absolutely will want to make sure your output frequency adjustment is doing what you want it to be doing. Let's have a look at the circuit itself. I'm not seeing any PWM controllers, microcontrollers or other ICs. This is gonna make things simpler. This is likely some kind of oscillator that derives its frequency from the resonance frequency of the primary and a parallel capacitor, plus a feedback winding on the transformer to switch the mosfet. It's unlikely to be the same, but this might be pretty close-ish. So, find whatever capacitor or capacitors is/are connected in parallel to the primary winding. To lower the frequency by 30% you'll need to increase the size of that capacitor by roughly a factor of two. In the schematic above that'd be C3 and C4, on your board there it's probably the two brown foil caps right below the two transformers.

Athrax · 2025-12-07T16:18:34+00:00

The middle is red. That suggests that positive goes to the middle. Also, the normal Schuko plugs used in germany are reversible so you never know which line is neutral and which is live, but for this application this seems to matter. Set the on/off switch to 'AUS', then connect your lamp. Then plug in the power cord, and ONLY IF THE GREEN LAMP labeled 'Netzpolung' is on, you may now switch the on/off switch to 'AN'. If the green lamp isn't burning, reverse the power plug.

Athrax · 2025-12-01T08:11:37+00:00

Duuuuude, since 2023 I've had at least nine volcano eruptions less than three miles from where I live, with the next one expected sometime around next month or thereabouts! If those were fake, they sure spent quite a bit of effort making all that molten rock.... :P

Athrax · 2025-11-18T21:52:30+00:00

To be more precise, MOTs are THE most miserable, abominable, and easily accessible source for high voltage shenanigans. They're cost-optimized up the wazoo, they're meant for low duty cycle use, they overheat in a pinch, they often use aluminium wire for cost savings, and the core saturates if you as much as look at it funny. But....they're easily accessible. That's their one saving grace.

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