Simple useful appliance?

On Wednesday, February 7, 2018 at 8:04:02 AM UTC-5, tabb...@gmail.com wrote:
> George said he needed a problem to think about.... here's a bit of a change from your usual design projects.
> 
> What's the simplest useful electronic product you can think of? Excluded are small amplifiers & oscillators, those have been done. Heating items such as kettles are excluded as they won't be very useful in this situation. Reaction radios are out due to legal issues.
> 
> By useful I mean in areas of the developing world where electricity 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 components.
> 
> It could be a domestic item, business item, manufacturing tool, anything of use.
> 
> 
> NT

Maybe something to automate this process:
https://www.liveleak.com/view?i=b4f_1414037735

On Thu, 8 Feb 2018 14:28:51 +0000, Martin Brown
<'''newspam'''@nezumi.demon.co.uk> wrote:

>On 07/02/2018 18:50, Rob wrote:
>> Jeff Liebermann <jeffl@cruzio.com> wrote:
>>> Developing world?  A fairly high percentage of people in Africa have
>>> cell phones or smartphones (to discourage POTS line copper theft):
>
>More because it allows them to leapfrog over fixed wire systems.
>In the UK it is becoming increasingly common not to have a fixed line.

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.
<https://www.statista.com/chart/2072/landline-phones-in-the-united-states/>
My guess(tm) is the curve will hit zero POTS phones in about 10 years.

>> Over here, making such a statement would result in you being called
>> a RACIST and being trending on Twitter all day.
>
>I don't know about that. It happens all over. When the copper price was 
>higher line theft of POTS and train signalling cable was rife in the UK.
>
>http://www.bbc.co.uk/news/uk-29109733
>
>They had to change the law to make "No questions asked" metal trading 
>illegal before things came under control. That and the price of copper 
>plunging cut theft of such cables down considerably.

The price of copper is steadily climbing again since it bottomed out
in 2015:
<http://www.infomine.com/investment/metal-prices/copper/all/>
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:
<https://www.netquote.com/home-insurance/copper-theft>



-- 
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

On Thursday, 8 February 2018 01:09:31 UTC, Jeff Liebermann  wrote:
> On Wed, 7 Feb 2018 15:47:26 -0800 (PST), tabbypurr wrote:
> >On Wednesday, 7 February 2018 23:18:42 UTC, Jeff Liebermann  wrote:

> >> capacity to run them.  Also, finding desktops that run on 12VDC is
> >> rather difficult. 
> 
> >Can you not get SM convertors for the various rails from ebay etc?
> 
> 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.
> 
> 2.  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.

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

> 3.  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.

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

> >> 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.
> 
> >those are way more reliable than electric light IME. Cheap too.
> >NT
> 
> Not really.  The mantles are fragile.  The glass globe is fragile. The

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

> kerosene stinks.  Pumping the kerosene lantern twice per hour gets a
> bit a bit tiresome. 

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

> Remembering to clean the dust off the lantern has
> been a problem. 

store them with covers on

> 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.

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


NT

On Thursday, 8 February 2018 02:19:11 UTC, John S  wrote:
> On 2/7/2018 2:44 PM, tabbypurr wrote:
> > On Wednesday, 7 February 2018 19:32:21 UTC, John S  wrote:
> >> On 2/7/2018 10:59 AM, Carl Ijames wrote:

> >>> What do you mean by a "reaction" radio?
> >>>
> >>
> >> Probably this:
> >>
> >> "A reflex radio receiver, occasionally called a reflectional receiver,
> >> is a radio receiver design in which the same amplifier is used to
> >> amplify the high-frequency radio signal (RF) and low-frequency audio
> >> (sound) signal"
> >>
> >> https://en.wikipedia.org/wiki/Reflex_receiver
> > 
> > Reflex and reaction are 2 different technologies. Sadly it seems the 2 refused to work well together.
> > 
> > 
> > NT
> > 
> 
> Please provide some links to reaction radio. I could not find any. I 
> would like to read about it.

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 circuit. The result is massive gain & good selectivity, but it's very unstable. The slightest thing sends it over the edge into squealing oscillation. Most 1930s radios were this type.


NT

On Thursday, 8 February 2018 06:37:46 UTC, Pimpom  wrote:
> On 2/8/2018 5:59 AM, tabbypurr wrote:
> > On Thursday, 8 February 2018 00:21:01 UTC, tabby  wrote:
> >> On Thursday, 8 February 2018 00:00:21 UTC, bitrex  wrote:
> >>> On 02/07/2018 06:48 PM, tabbypurr wrote:
> >>>> On Wednesday, 7 February 2018 23:15:55 UTC, bitrex  wrote:
> >>>>> On 02/07/2018 08:03 AM, tabbypurr wrote:
> >>>>
> >>>>>> George said he needed a problem to think about.... here's a bit of a change from your usual design projects.
> >>>>>>
> >>>>>> What's the simplest useful electronic product you can think of? Excluded are small amplifiers & oscillators, those have been done. Heating items such as kettles are excluded as they won't be very useful in this situation. Reaction radios are out due to legal issues.
> >>>>>>
> >>>>>> By useful I mean in areas of the developing world where electricity 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 components.
> >>>>>>
> >>>>>> It could be a domestic item, business item, manufacturing tool, anything of use.
> >>>>>>
> >>>>>>
> >>>>>> NT
> >>>>>>
> >>>>>
> >>>>> The 555 timer rain alarm is a classic that's pretty useful in areas of
> >>>>> the world that get unpredictable, sudden torrential downpours:
> >>>>>
> >>>>> <https://electrosome.com/wp-content/uploads/2016/06/Rain-Alarm-using-555-Timer-PCB-1.jpg>
> >>>>
> >>>> Could you explain how it would be useful?
> >>>>
> >>>>
> >>>> 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.
> >>
> >> I like that one.
> >>
> >>
> >> NT
> > 
> > 3 - 15mA quiescent is pretty grim though, will need to use another oscillator.
> > 
> 
> They can use the CMOS versions with ~100uA of standby current. 
> They have enough output to drive those small buzzers. If not, a 
> single transistor and a resistor can be added.

Sometimes, yes. What percentage of scrap electronic items contain a cmos 555? 

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


NT

On Thursday, 8 February 2018 07:40:57 UTC, Jeff Liebermann  wrote:
> On Wed, 7 Feb 2018 23:16:57 -0800 (PST), tabbypurr wrote:

> >> 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.
> 
> >We rarely lose power over here, and when it happens it's not 
> >for long enough to be a real problem. 
> 
> In the People's Republic of Santa Cruz (California), we have
> successfully extended a previous 30 minute line restoration process,
> into a bureaucratic exercise in power politics last most of the day.
> I'll spare you the details.  Minimum time to restore for a simple wire
> down is now about 3 hrs.  If a tree or pole is involved, about 8 hrs.

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


> >Having maintained both electric & gas backup lighting I'd choose 
> >gas any day, far more reliable long term.
> 
> I'm undecided.  When the power goes out, I usually just grab a book
> and spend the time reading.  I can do that by either electric or gas
> lighting.  Electric is easier, but gas or kerosene are more relaxing
> and romantic.
> 
> >I'm not sure why you're refilling lights in the dark if 
> >you have 12 of them.
> 
> Repeating, I currently have 6 lanterns.  I once had 12 lanterns.
> 
> Unless I'm trying to work on some storm damage to the house at night:
> <http://www.learnbydestroying.com/jeffl/pics/Storm-Damage-2011-12-03/index.html>
> I only run one or maybe two lanterns (upstairs and downstairs) at a
> time.  I move it around the house as needed.  I really don't think
> it's a good idea to refill one lantern with kerosene, while having the
> work area illuminated by the open flame of another lantern.  If
> possible, I use electric illumination during refilling.  However, it's
> still dangerous to refill a hot lantern (or generator).  

It's a long time since I ran paraffin kit, though IIRC it was frugal on fuel. 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 fwiw, a ceiling hung lantern in the same room as a live kero refill isn't hazardous. Different story for gas of course, or the more volatile fuels. Boiling petrol lanterns are not recommended on safety grounds.


NT

On Thursday, 8 February 2018 09:13:27 UTC, Rob  wrote:
> Pimpom <Pimpom@invalid.invalid> wrote:
> > On 2/8/2018 4:29 AM, bitrex wrote:
> >> On 02/07/2018 01:50 PM, Rob wrote:
> >>> Jeff Liebermann <jeffl@cruzio.com> wrote:
> >>>> Developing world?  A fairly high percentage of people in Africa have
> >>>> cell phones or smartphones (to discourage POTS line copper theft):
> >>>
> >>> Over here, making such a statement would result in you being called
> >>> a RACIST and being trending on Twitter all day.
> >>>
> >> 
> >> An unqualified statement "Africans tend to steal stuff" probably would.
> >> That isn't what he said
> >> 
> >
> > The implication would be enough to set off a lot of people.
> 
> And indeed it is.
> 
> Here, a big row resulted from a referral to average IQ vs country, not
> even made directly but from the refusal to it being withspoken.
> 
> Of course only because the IQ of Africans tends to be much lower in
> such statistics.  Nobody had a problem with the IQ of Asians tending
> to be higher.

Africa suffers from brain drain. We benefit from it.


NT

On Thursday, 8 February 2018 10:36:56 UTC, piglet  wrote:
> On 07/02/2018 20:44, tabbypurr wrote:
> > 
> > Reflex and reaction are 2 different technologies. Sadly it seems the 2 refused to work well together.
> 
> Sir Douglas Hall devised the gloriously named "Spontaflex" receiver. 
> Reflex and regenerative (aka reaction) - later designs had an RF buffer 
> between antenna and regenerative detector so were social to other band 
> listeners. Naturally he reflexed the RF buffer so it also amplified AF.
> 
> All fun ingenious stuff. I built one circa 1970 and still have it, works 
> beautifully, with delicate fingers can resolve SSB speech on the 75/80m 
> ham band.
> 
> Many were published in British mag "Radio Constructor" available on 
> americanradiohistory.com Also:
> <http://www.spontaflex.free-online.co.uk>
> 
> piglet

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


NT

In article <da7bf34d-78a3-408f-95eb-3c26eacd8ece@googlegroups.com>,
 <tabbypurr@gmail.com> wrote:

>> Please provide some links to reaction radio. I could not find any. I 
>> would like to read about it.
>
>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 circuit. The result is massive gain & good selectivity, but it's very unstable. The
>slightest thing sends it over the edge into squealing oscillation. Most 1930s radios were this type.

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

https://en.wikipedia.org/wiki/Regenerative_circuit

On Thu, 08 Feb 2018 08:31:26 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:


>The price of copper is steadily climbing again since it bottomed out
>in 2015:
><http://www.infomine.com/investment/metal-prices/copper/all/>
>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:
><https://www.netquote.com/home-insurance/copper-theft>

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.