Simple useful appliance?

Same thing in the USA. The resurrected AT&T monopoly is doing its best to get out of the regulated POTS business. About half the US households still have POTS phones, but that number is linearly decreasing. My guess(tm) is the curve will hit zero POTS phones in about 10 years.

The price of copper is steadily climbing again since it bottomed out in 2015: Copper theft protection services and products have become required for unmanned mountain top radio sites and the cost of insurance has climbed faster than the price of copper. Similar problem for the homeowner:

I assumed the nominally 12/24/48v would need to go through a SMPSU to make it real 12v.

Things that take ac warts normally have a BR+C on the input, so they run fi ne off dc. Maybe you have some exceptions. I don't encounter many positive grounded warts.

sure. Battery systems are still less reliable. Hang your lights where they won't get whacked.

propane/butane are easier & safer and don't whiff

store them with covers on

We rarely lose power over here, and when it happens it's not for long enoug h to be a real problem. Having maintained both electric & gas backup lighti ng I'd choose gas any day, far more reliable long term. I'm not sure why yo u're refilling lights in the dark if you have 12 of them.

NT

refused to work well together.

I googled for too long, but found nothing that explains the basic concept & issues. A variable amount of rf is fed back from rf amp anode to grid circ uit. The result is massive gain & good selectivity, but it's very unstable. The slightest thing sends it over the edge into squealing oscillation. Mos t 1930s radios were this type.

NT

a change from your usual design projects.

cluded are small amplifiers & oscillators, those have been done. Heating it ems such as kettles are excluded as they won't be very useful in this situa tion. Reaction radios are out due to legal issues.

y is available to a percentage of users. The item must be makeable entirely from parts from scrap, your digikey budget is zero. So no uncommon compone nts.

ything of use.

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Sometimes, yes. What percentage of scrap electronic items contain a cmos 55

What percentage contain a few transistors to make a discrete oscillator? Al most all.

NT

I wonder why. Ours can be as short as 10 minutes. Underground cable meltdow ns are fixed overnight.

It's a long time since I ran paraffin kit, though IIRC it was frugal on fue l. Gas lights contain enough to last many power cuts. I also don't know why you would refill them while still hot when you have 5 others to use. And f wiw, a ceiling hung lantern in the same room as a live kero refill isn't ha zardous. Different story for gas of course, or the more volatile fuels. Boi ling petrol lanterns are not recommended on safety grounds.

NT

Africa suffers from brain drain. We benefit from it.

NT

interesting site. My brain just isn't following the circuits!

NT

More information might be found under "regenerative" or "super-regenerative" radio receiver design.

We had to replace some of our heavy tower grounding leads with aluminum cable. Less than idea. Tried spray painting copper ones with aluminum spray paint. That seemed to work. We actually caught one bunch of thieves in the act. Bunch of idiot rednecks. (warning: trigger).

It was a public safety site--police and fire dispatch. They got in a fair amount of trouble.

We've had a good number of the Sola conditioners go off. Bad oil caps I guess. They don't regulate much from the load side either. Done with them now.

Oh good, I thought it just might be me. :^)

George h.

it always struck me that the solution to cable theft would be to move from copper to CCA where practical. The mix of metals hugely reduces their scrap value, plus the cable is cheaper to buy.

NT

I had a modem that used the AC to generate -12V for the RS232, actually still got it. but don't have a copper phone service anymore.

next time buy a panasonic cordless telephone. (not positive ground, but positive on the outer contact).

Thses phones seem to inclide a "magic smoke reservoir" (possibly a diode across the DC-IN) mine all have at some time sent smoke signals due to incorrect polarity, they seem to have some remaining smoke, as they still work.

Copper clad aluminum will work nicely at RF frequencies, where the only thing of importance is surface conductivity via skin effect. However, if one is looking for a low frequency 60 Hz ground for AC power wiring, or a DC ground for lightning protection, CCA won't work. Towers also have to deal with building codes and construction specifications many of which don't allow CCA wire.

That also includes CCA CAT5 ethernet and phone cable, which is commonly available online but which is not recognized by any wiring specifications. 100% copper is required to meet CAT specifications and CCA CAT5/6 cable is generally considered to be "counterfeit" because it can't meet any of the required specifications.

Various hits for CCA cable:

Communications Cable & Connectivity Association For example:

Of course, some groups think that CCA is just fine for some types of residential wiring:

that just isn't true.

Maybe it's time to change the regs to permit CCA with a low %age of ali, purely to make it unattractive to thieves. US home CCA mains wire is 90% ali, which is more brittle than Cu. 10% ali would not be significantly affected.

NT