On Wednesday, 7 February 2018 23:44:30 UTC, Jeff Liebermann wrote:> On Wed, 7 Feb 2018 11:21:23 -0800 (PST), tabbypurr wrote: > >On Wednesday, 7 February 2018 17:00:17 UTC, Carl Ijames wrote:> >> 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 > > Do you mean super regenerative receivers? > Most of the common 315/433MHz radio links have super regenerative > receivers: > <https://www.alibaba.com/showroom/433mhz-superregeneration-wireless-receiver-module.html> > <https://www.google.com/patents/US20020168957>regenerative not superregenerative. Early reaction sets were manually adjusted, creating a legal problem. Automate the procss and you've upped the part count - that doesn't matter in an IC, but does when building a minimal set. In principle one could simply set the pfb at a level where it won't cause feedback under any specified conditions. Of course some semibright spark will then modify the things to receive better and lots of infringing sets will get out, a situation no-one wants. NT
Simple useful appliance?
Started by ●February 7, 2018
Reply by ●February 7, 20182018-02-07
Reply by ●February 7, 20182018-02-07
On 02/07/2018 06:48 PM, tabbypurr@gmail.com 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.
Reply by ●February 7, 20182018-02-07
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. > > > NTOK 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.
Reply by ●February 7, 20182018-02-07
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
Reply by ●February 7, 20182018-02-07
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. > > > NT3 - 15mA quiescent is pretty grim though, will need to use another oscillator. NT
Reply by ●February 7, 20182018-02-07
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?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. ?
Reply by ●February 7, 20182018-02-07
On Wed, 7 Feb 2018 15:47:26 -0800 (PST), tabbypurr@gmail.com 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. 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.>> 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. >NTNot 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
Reply by ●February 7, 20182018-02-07
On 2/7/2018 2:44 PM, tabbypurr@gmail.com wrote:> 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_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.
Reply by ●February 7, 20182018-02-07
On 02/07/2018 07:29 PM, tabbypurr@gmail.com 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. > > > NT >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: <https://xod.io/> 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
Reply by ●February 7, 20182018-02-07
On 2/7/2018 1:46 PM, Pimpom wrote:> 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. >Yes, I agree.
