On 2/7/2018 12:09 PM, Jeff Liebermann wrote:> On Wed, 7 Feb 2018 05:03:57 -0800 (PST), tabbypurr@gmail.com wrote: > >> By useful I mean in areas of the developing world where electricity >> is available to a percentage of users. > > Or, a percentage of time. I'm told that power in the developing world > is often intermittent and unreliable. I have that problem living in > the forest, where the power wires are known to attract falling trees. > Damage to electronics from voltage surges usually occurs when the > power is restored, so I unplug or turn off (at the breaker panel) > power to any sensitive devices. The problem is that in the middle of > the night, there's no easy way for me to determine that the power had > been restored. So, I built a "Power Restoration Wake Up Alarm" that > makes loud buzzing noises when power comes back. This might be a bit > too complicated for the proposed design project. Instead, I suggest > inserting a small power diode (1N4002) into the wall outlet. When the > power returns, the diode explodes, making enough noise to alert or > wake the residents. It can't get much simpler than a single diode. >Capacitor, 2 resistors, and 2 LEDs in anti-parallel is an indicator of power. I use a night light.
Simple useful appliance?
Started by ●February 7, 2018
Reply by ●February 7, 20182018-02-07
Reply by ●February 7, 20182018-02-07
On Wednesday, 7 February 2018 17:00:17 UTC, Carl Ijames wrote:> On Wednesday, 7 February 2018 16:02:26 UTC, Wond wrote: > > On Wed, 07 Feb 2018 05:03:57 -0800, 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 > > > > How about those AC outlet testers- a plug with indicators. > > I once made a DC polarity indicator for a guy, so he wouldn't blow his > > VHF radio moving it from boat to boat. > > Yes - that's been done too though. > > > NT > ============================================ > > Did they include frequency so they could verify proper generator rpm? > > What do you mean by a "reaction" radio?positive feedback on the rf circuit - good sensitity, goodish selectivity with minimal parts count. The downside is the risk of oscillation and unintended broadcast of this interference, so they're no go. NT
Reply by ●February 7, 20182018-02-07
On 2/7/2018 10:59 AM, Carl Ijames wrote:> On Wednesday, 7 February 2018 16:02:26 UTC, Wond wrote: >> On Wed, 07 Feb 2018 05:03:57 -0800, 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 >> >> How about those AC outlet testers- a plug with indicators. >> I once made a DC polarity indicator for a guy, so he wouldn't blow his >> VHF radio moving it from boat to boat. > > Yes - that's been done too though. > > > NT > ============================================ > > Did they include frequency so they could verify proper generator rpm? > > 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
Reply by ●February 7, 20182018-02-07
On Wednesday, 7 February 2018 17:00:17 UTC, Carl Ijames wrote:> On Wednesday, 7 February 2018 16:02:26 UTC, Wond wrote: > > On Wed, 07 Feb 2018 05:03:57 -0800, 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 > > > > How about those AC outlet testers- a plug with indicators. > > I once made a DC polarity indicator for a guy, so he wouldn't blow his > > VHF radio moving it from boat to boat. > > Yes - that's been done too though. > > > NT > ============================================ > > Did they include frequency so they could verify proper generator rpm? > > What do you mean by a "reaction" radio?positive feedback on the rf circuit - good sensitity, goodish selectivity with minimal parts count. The downside is the risk of oscillation and unintended broadcast of this interference, so they're no go. NT
Reply by ●February 7, 20182018-02-07
On 2/8/2018 12:48 AM, John S wrote:> On 2/7/2018 12:09 PM, Jeff Liebermann wrote: >> On Wed, 7 Feb 2018 05:03:57 -0800 (PST), tabbypurr@gmail.com wrote: >> >>> By useful I mean in areas of the developing world where electricity >>> is available to a percentage of users. >> >> Or, a percentage of time. I'm told that power in the developing world >> is often intermittent and unreliable. I have that problem living in >> the forest, where the power wires are known to attract falling trees. >> Damage to electronics from voltage surges usually occurs when the >> power is restored, so I unplug or turn off (at the breaker panel) >> power to any sensitive devices. The problem is that in the middle of >> the night, there's no easy way for me to determine that the power had >> been restored. So, I built a "Power Restoration Wake Up Alarm" that >> makes loud buzzing noises when power comes back. This might be a bit >> too complicated for the proposed design project. Instead, I suggest >> inserting a small power diode (1N4002) into the wall outlet. When the >> power returns, the diode explodes, making enough noise to alert or >> wake the residents. It can't get much simpler than a single diode. >> > > > Capacitor, 2 resistors, and 2 LEDs in anti-parallel is an indicator of > power. > > I use a night light. >I used exactly the same thing for a few years until I switched to the visual-plus-audible mains alarm that I posted here in another thread some time ago. One could even dispense with the capacitor and use a single resistor. Not much current needed just for a visual indicator. 82-100k quarter-watt for 120V and 150k half-watt in a 230V system.
Reply by ●February 7, 20182018-02-07
sms wrote:> On 2/7/2018 10:09 AM, Jeff Liebermann wrote: > > <snip> > >> Instead, I suggest >> inserting a small power diode (1N4002) into the wall outlet. When the >> power returns, the diode explodes, making enough noise to alert or >> wake the residents. It can't get much simpler than a single diode. > > Simple, but idiotic. A single tiny explosion isn't going to do much. > > When the power goes out connect an 18650, unprotected, Li-Ion battery > into the wall outlet. When the power is restored the Li-Ion battery will > explode and start a small fire which will then trigger the smoke alarm. > The continuous alarm is more likely to be effective.I like how you think... handheld population control. Heheheh... Lead 'em down the path... to the next plane of existence. The absolute best way is to have a nice say 22kW Generac backup generator AND a good power conditioner on your system. Then, you simply go to sleep without a worry about what happens or happened to your power that night. Put some of your lights, your heating and air system, your kitchen, and your computer UPSs on it. Your neighbors will always say "he's the only one on the street who's lights never go out.
Reply by ●February 7, 20182018-02-07
On 2/8/2018 1:02 AM, 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 >Back in the early 1970s, I made several *non*-reflex, non-superhet radios with a single transistor RF stage and gave them away as novelty gifts. The RF stage was fixed tuned to the local AM station which conveniently broadcast at 540 kHz. I used readily available 455 kHz IFTs after removing the capacitor - usually 200pF - and replacing it with 150pF to enable them to tune to 540 kHz. A Ge A079 diode served as the detector and I even included AGC. For the RF stage, I used whatever RF transistor I had on hand - AF117, 2SA15 (PNPs) or BF195 (NPN).
Reply by ●February 7, 20182018-02-07
On Wednesday, 7 February 2018 19:07:56 UTC, Bill Martin wrote:> On 02/07/2018 10:09 AM, Jeff Liebermann wrote: > > On Wed, 7 Feb 2018 05:03:57 -0800 (PST), tabbypurr wrote: > > > >> By useful I mean in areas of the developing world where electricity > >> is available to a percentage of users. > > > > Or, a percentage of time. I'm told that power in the developing world > > is often intermittent and unreliable. I have that problem living in > > the forest, where the power wires are known to attract falling trees. > > Damage to electronics from voltage surges usually occurs when the > > power is restored, so I unplug or turn off (at the breaker panel) > > power to any sensitive devices. The problem is that in the middle of > > the night, there's no easy way for me to determine that the power had > > been restored. So, I built a "Power Restoration Wake Up Alarm" that > > makes loud buzzing noises when power comes back. This might be a bit > > too complicated for the proposed design project. Instead, I suggest > > inserting a small power diode (1N4002) into the wall outlet. When the > > power returns, the diode explodes, making enough noise to alert or > > wake the residents. It can't get much simpler than a single diode. > > > How about an ac relay, normally open type, in the power line input to > the gadget you want to protect, with the coil powered from the "on" > contact side. Power drops out, relay disconnects from power line, power > comes back but will not energize the relay until you manually reset it, > by pushing the contactor down by hand. Use a stick to push it!I'm not clear what appliances would be protected from what NT
Reply by ●February 7, 20182018-02-07
On Wednesday, 7 February 2018 19:32:21 UTC, John S wrote:> On 2/7/2018 10:59 AM, Carl Ijames wrote: > > On Wednesday, 7 February 2018 16:02:26 UTC, Wond wrote: > >> On Wed, 07 Feb 2018 05:03:57 -0800, 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 > >> > >> How about those AC outlet testers- a plug with indicators. > >> I once made a DC polarity indicator for a guy, so he wouldn't blow his > >> VHF radio moving it from boat to boat. > > > > Yes - that's been done too though. > > > > > > NT > > ============================================ > > > > Did they include frequency so they could verify proper generator rpm? > > > > 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_receiverReflex and reaction are 2 different technologies. Sadly it seems the 2 refused to work well together. NT
Reply by ●February 7, 20182018-02-07
On Wed, 07 Feb 2018 05:03:57 -0800, tabbypurr wrote:> 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.Coconut powered shortwave radio. -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.
