Simple useful appliance?

9 volt battery + steel wool to start a fire

The 555 timer rain alarm is a classic that's pretty useful in areas of the world that get unpredictable, sudden torrential downpours:

I hope you don't mean a ferroresonant transformer as a "power conditioner". They work nicely, as long as you feed it with 60 Hz. Low in frequency, and the output voltage drops. High in frequency, and it climbs. Details: Also, they're not very efficient (about 75%), get rather warm, and buzz loudly. Despite these disadvantages, I've used them effectively with computers in place of a UPS. I was doing some programming during a lightning storm. The overhead fluorescent lights were flashing intermittently as the power flickered on and off, but the computah never missed a beat.

Most generators do not produce a clean sine wave or deliver a constant

60.0 Hz. The result is an even worse looking waveform from the ferroresonant xformer, wide voltage variations, or both. Therefore, I would recommend *EITHER* a generator or a ferroresonant power conditioner, but not both.

What, me worry? Most of my critical gizmos are DC charged or operated. I went through considerable difficulty finding phones, answering machinery, modems, routers, switches, media players, TV, hi-fi, etc, that run on 10-14VDC (also known as 12VDC nominal). These are run by several big lead-acid or gel cell batteries, and charged by either a marine battery charger during the winter, or a solar panel during the summer. If the power goes out at night, I usually don't notice.

The desktop computahs and one big monitor are the only devices with UPS protection because my battery system simply doesn't have the capacity to run them. Also, finding desktops that run on 12VDC is rather difficult. The plan is to switch to lower power desktop computers (laptop in a box) which will run on battery power, and dispose of the UPS.

That's been a problem. We had a storm a few years ago that dropped quite a few trees in the area. The power utility (PG&E) ran around fixing downed power lines. Mine was one of the last to get fixed because the lineman saw that my house was normally lighted and drove by thinking that I had working utility power. I switched to kerosene and propane lamps for emergency lighting and have not had that problem again.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

you miss the power surge when it is restored...

I can sorta see how that might be useful. However, you have not met the original design requirements, which I understand to be:

1. Keep George Herold busy and out of trouble.
2. Design the "simplest useful electronic product". I'm assuming that means minimum components count.
3. Operate in an area where power is only available to a "percentage" of users. I interpret this to mean unreliable power or no power at all.
4. "Must be makeable entirely from parts from scrap" which eliminates any purchased, custom, new, exotic, sophisticated, or expensive components. In other words, made for eWaste.
5. "Could be a domestic item, business item, manufacturing tool, anything of use".

As I see it, your proposed device would not meet any of these design requirements. Well, maybe #5, which is inordinately broad.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

well, I can't help there :-)

One part...not minimal enough?

Well, no power at all, who cares..nothing is going to work anyway. This might help with the intermittent case.

There must be some discarded household thing with a big relay in it...washing machine maybe?

Oh well, I'm not forcing anybody to build it!

>

Do you mean super regenerative receivers? Most of the common 315/433MHz radio links have super regenerative receivers:

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Can you not get SM convertors for the various rails from ebay etc?

those are way more reliable than electric light IME. Cheap too.

NT

ange from your usual design projects.

d are small amplifiers & oscillators, those have been done. Heating items s uch as kettles are excluded as they won't be very useful in this situation. Reaction radios are out due to legal issues.

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

g of use.

Could you explain how it would be useful?

NT

regenerative not superregenerative. Early reaction sets were manually adjus ted, creating a legal problem. Automate the procss and you've upped the par t count - that doesn't matter in an IC, but does when building a minimal se t.

In principle one could simply set the pfb at a level where it won't cause f eedback under any specified conditions. Of course some semibright spark wil l then modify the things to receive better and lots of infringing sets will get out, a situation no-one wants.

NT

Rainwater is a big source of potable water for many people in developing countries, particularly during times of extreme drought. But you don't wanna just leave the cans or barrels or catch-basins or storage tank channel entry points open all the time, open standing water is generally dangerous, animals and insects poop and piss and possibly crawl in and die in there, mosquitoes use it to lay eggs and spread Dengue fever, and generally contaminate it up.

So you keep them sealed but what happens if it rains in the middle of the night when everyone's asleep? Can you guarantee anyone will hear it and get up to collect it? That 15 minute downpour might be the only bonus fresh water you get for a week.

On Wednesday, February 7, 2018 at 8:04:02 AM UTC-5, snipped-for-privacy@gmail.com wrote :

ge from your usual design projects.

are small amplifiers & oscillators, those have been done. Heating items suc h as kettles are excluded as they won't be very useful in this situation. R eaction radios are out due to legal issues.

ailable to a percentage of users. The item must be makeable entirely from p arts from scrap, your digikey budget is zero. So no uncommon components.

of use.

OK I've got a very simple device I've wanted to make, but for myself. :^)

The device is a fet, and I want to use it as a heater and a temperature sensor. I've got at least two applications, the second* of which is a heat capacity, thermal thumper. Pulse a known amount of energy and measure T as a function of time. So I need a good sample and hold circuit, that's something I've never done before, a good cap and a good switch... suggestions?

George H.

*first is a thermal control loop.

change from your usual design projects.

ded are small amplifiers & oscillators, those have been done. Heating items such as kettles are excluded as they won't be very useful in this situatio n. Reaction radios are out due to legal issues.

s available to a percentage of users. The item must be makeable entirely fr om parts from scrap, your digikey budget is zero. So no uncommon components .

ing of use.

I like that one.

NT

a change from your usual design projects.

luded are small amplifiers & oscillators, those have been done. Heating ite ms such as kettles are excluded as they won't be very useful in this situat ion. Reaction radios are out due to legal issues.

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 componen ts.

thing of use.

of

g

y

d

3 - 15mA quiescent is pretty grim though, will need to use another oscillat or.

NT

An electronic bullet. ? Even if it doesn't work quite right, you can still take out the person sitting next to you.

Useful?

The world is over-populated as it is. Plus, those 3rd-world lives are miserable. You'd be doing them a favor. ?

Sure. I could buy a pile of buck converters and run them on 24v or maybe 48VDC. I actually tried a few of those and ran into problems:

1. The RFI is horrendous. None of them could ever pass an FCC Part

19 incidental radiation test. When the power is out, I like to run my various ham and commercial radios, as well as scanners. That last thing I need if EMI/RFI. Shielding an a ton of ferrite beads will help, but I prefer to avoid the problem.

1. Many devices are labeled +12VDC without a clue what voltage it will tolerate. I've found some that will operate from 6 to 14VDC, while others need 12.000000 volt regulated. This makes running off a

12V battery, which can be anywhere from 11 to 16VDC. Usually, that means reverse engineering the devices power supply regulator and measuring what happens with a variable voltage bench supply.

1. There are a few companies that like to make my life miserable by supplying AC or positive ground wall warts. These do not fit easily into a DC bus/rail type arrangement.

Not really. The mantles are fragile. The glass globe is fragile. The kerosene stinks. Pumping the kerosene lantern twice per hour gets a bit a bit tiresome. Remembering to clean the dust off the lantern has been a problem. Refilling a hot lantern in the dark is dangerous. LED lights would probably be better and easier, but I prefer mantle type lights because the light seems rather "relaxing" while LED's tend to be "harsh". Incidentally, I currently have 6 assorted Coleman lanterns, down from about 12 a few years ago. All are functional. Some of my friends are collectors and have many more.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Please provide some links to reaction radio. I could not find any. I would like to read about it.

Here in the first world I don't use analog chips like the 555 for low-frequency sense/timer/control stuff anymore, I have this software suite that lets you build small apps for microcontrollers graphically:

Drag and drop a couple nodes, wire them up like making a GUI in Visual Basic, punch a button and upload to the chip, takes aoout 5 minutes, delay times of up to years probably and no external parts. A reel of 75 cent 8 pin ATTiny85s = universal random thing building block

Yes, I agree.