On Mon, 13 Mar 2023 06:12:48 GMT, Jan Panteltje <alien@comet.invalid> wrote:>On a sunny day (Sun, 12 Mar 2023 20:34:46 -0000 (UTC)) it happened Mike Monett >VE3BTI <spamme@not.com> wrote in <XnsAFC5A8A94531Didtokenpost@88.198.57.247>: > >>Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> Or failing that, a regular low-barrier Schottky detector and a Joule >>> Thief to drive the LED. >>> >>> Might be fun making a Joule Thief out of a depletion pHEMT. ;) >>> >>> Cheers >>> >>> Phil Hobbs >> >>Need about 1V at some current >> >>Diodes Inc. ZXSC310E5 >> >>https://octopart.com/search?q=ZXSC310E5¤cy=USD&specs=0 >> >>or >> >>2 X 2N3904 >>https://www.edn.com/single-cell-lights-any-led/ >> >>or >> >>BC550C, 2N2222, BYV1030 >> >>https://www.electronicdesign.com/technologies/leds/article/21802105/ledstri >>ng-driver-operates-from-single-cell > >Yes, but mine runs from a simple thermocouple : > http://panteltje.nl/pub/lighting_a_LED_with_a_candle_IMG_3604.GIF > > JFET (you only need 1 for a LED). > >In the case of John Larkin's radio tower we need to know the frequency. >In this circuit you can get a lot of voltage gain like this: > >\ / antenna > | > | tunable core > | --------------- > | || | | | > | || ( |a |k > ) || ( LED1 LED2 > | || ( |k |a > | | | | > |-------------------- > | >/// >GNDYes. With RF from an antenna, impedance matching is easy. But a schottky diode or two might still help. Given my case, 22 megawatts spread over about 4 decades of frequency, it would be academically fun to use a lot of spectrum to power my LED. I recall a project in Popular Electronics magazine where they rectified a bunch of the AM spectrum to power a 1-transistor amplifier to gain up one of the stations and drive a loudspeaker. Cute.> >Basically the normal antique antenna circuit, >Slide in a ferroxcube rod and you can tune it with that if it is AM medium wave, no antenna needed. > > >LEDs also work great on higher frequencies, I had a LED on my GPA 27 MHz CB antenna output once >and it would light up when the neighbor across the street transmitted, >Or something like this: > http://panteltje.nl/pub/testing_the_20_meter_inductive_loop_antenna_IMG_4536.JPGI tested one LED that would make light as fast as I could drive and measure it, about 2 ns in my case. I think some other LEDs are slow and have high capacitance.
MOSFET Needed
Started by ●March 8, 2023
Reply by ●March 13, 20232023-03-13
Reply by ●March 13, 20232023-03-13
On a sunny day (Mon, 13 Mar 2023 08:11:32 -0700) it happened John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote in <3reu0i959g26722rhbrp97baaqvingl0r4@4ax.com>:>On Mon, 13 Mar 2023 06:12:48 GMT, Jan Panteltje <alien@comet.invalid> >wrote: > >>On a sunny day (Sun, 12 Mar 2023 20:34:46 -0000 (UTC)) it happened Mike Monett >>VE3BTI <spamme@not.com> wrote in <XnsAFC5A8A94531Didtokenpost@88.198.57.247>: >> >>>Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> Or failing that, a regular low-barrier Schottky detector and a Joule >>>> Thief to drive the LED. >>>> >>>> Might be fun making a Joule Thief out of a depletion pHEMT. ;) >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>>Need about 1V at some current >>> >>>Diodes Inc. ZXSC310E5 >>> >>>https://octopart.com/search?q=ZXSC310E5¤cy=USD&specs=0 >>> >>>or >>> >>>2 X 2N3904 >>>https://www.edn.com/single-cell-lights-any-led/ >>> >>>or >>> >>>BC550C, 2N2222, BYV1030 >>> >>>https://www.electronicdesign.com/technologies/leds/article/21802105/ledstri >>>ng-driver-operates-from-single-cell >> >>Yes, but mine runs from a simple thermocouple : >> http://panteltje.nl/pub/lighting_a_LED_with_a_candle_IMG_3604.GIF >> >> JFET (you only need 1 for a LED). >> >>In the case of John Larkin's radio tower we need to know the frequency. >>In this circuit you can get a lot of voltage gain like this: >> >>\ / antenna >> | >> | tunable core >> | --------------- >> | || | | | >> | || ( |a |k >> ) || ( LED1 LED2 >> | || ( |k |a >> | | | | >> |-------------------- >> | >>/// >>GND > > >Yes. With RF from an antenna, impedance matching is easy. But a >schottky diode or two might still help. > >Given my case, 22 megawatts spread over about 4 decades of frequency, >it would be academically fun to use a lot of spectrum to power my LED.Well, that is almost always a hit for some length of wire :-) Did you ever try a LED on a 1/2 wave antenna? this is the type of CB antenna I used: https://moonrakeronline.com/eu/venom-gpa-1-2-wave-base-antenna The bandwidth is really small, only about 2 MHz, you can fine tune SWR with the length... It is 50 Ohms out, has a matching transformer inside: https://pe4bas.blogspot.com/2014/12/whats-inside-old-gpa-27-12.html You can make your own for any other frequency (length). Need to know the frequency very precisely. The loop antenna has even smaller bandwidth: https://panteltje.nl/pub/testing_the_20_meter_inductive_loop_antenna_IMG_4536.JPG https://panteltje.nl/pub/testing_the_20_meter_inductive_loop_antenna_dunno_IMG_4537.JPG Must have been > 1.5V pp for the LED to glow brightly.... :-) I asked my neighbor how many watts he was putting out, but he kept that a secret there is a legal limit on the amount of watts you can use here for CB transmission. Else just a RF inductor to ground with LED in parallel, any length of wire (depending on frequency)?>I recall a project in Popular Electronics magazine where they >rectified a bunch of the AM spectrum to power a 1-transistor amplifier >to gain up one of the stations and drive a loudspeaker. Cute. > >> >>Basically the normal antique antenna circuit, >>Slide in a ferroxcube rod and you can tune it with that if it is AM medium wave, no antenna needed. >> >> >>LEDs also work great on higher frequencies, I had a LED on my GPA 27 MHz CB antenna output once >>and it would light up when the neighbor across the street transmitted, >>Or something like this: >> http://panteltje.nl/pub/testing_the_20_meter_inductive_loop_antenna_IMG_4536.JPG > >I tested one LED that would make light as fast as I could drive and >measure it, about 2 ns in my case. I think some other LEDs are slow >and have high capacitance.27 MHz was a cheap LED from local shop I think. I now have a nice assortment of different colors and 2 sizes from ebay, something like this: https://www.ebay.com/itm/385132659452 200 for $8.96 So, now I am posting this from the Raspberry Pi4 8 GB with a new compiled NewsFleX usenet reader I wrote. (else I used the laptop). Cut and paste is a bit easier that way, else I have to ssh to the other thing all the time. Tried that Pi4 thing yet? Now also have Apache webserver running on it (to test website things before I upload i). I see I need to install ispell spellchecker on this Pi4 now.... just did (apt-get install ispell), but no go: Can't open /usr/lib/ispell/english.hash So sorry for any typos :-)
Reply by ●March 13, 20232023-03-13
On 2023-03-13 11:11, John Larkin wrote:> On Mon, 13 Mar 2023 06:12:48 GMT, Jan Panteltje <alien@comet.invalid> > wrote: > >> On a sunny day (Sun, 12 Mar 2023 20:34:46 -0000 (UTC)) it happened Mike Monett >> VE3BTI <spamme@not.com> wrote in <XnsAFC5A8A94531Didtokenpost@88.198.57.247>: >> >>> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> Or failing that, a regular low-barrier Schottky detector and a Joule >>>> Thief to drive the LED. >>>> >>>> Might be fun making a Joule Thief out of a depletion pHEMT. ;) >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> Need about 1V at some current >>> >>> Diodes Inc. ZXSC310E5 >>> >>> https://octopart.com/search?q=ZXSC310E5¤cy=USD&specs=0 >>> >>> or >>> >>> 2 X 2N3904 >>> https://www.edn.com/single-cell-lights-any-led/ >>> >>> or >>> >>> BC550C, 2N2222, BYV1030 >>> >>> https://www.electronicdesign.com/technologies/leds/article/21802105/ledstri >>> ng-driver-operates-from-single-cell >> >> Yes, but mine runs from a simple thermocouple : >> http://panteltje.nl/pub/lighting_a_LED_with_a_candle_IMG_3604.GIF >> >> JFET (you only need 1 for a LED). >> >> In the case of John Larkin's radio tower we need to know the frequency. >> In this circuit you can get a lot of voltage gain like this: >> >> \ / antenna >> | >> | tunable core >> | --------------- >> | || | | | >> | || ( |a |k >> ) || ( LED1 LED2 >> | || ( |k |a >> | | | | >> |-------------------- >> | >> /// >> GND > > > Yes. With RF from an antenna, impedance matching is easy. But a > schottky diode or two might still help. > > Given my case, 22 megawatts spread over about 4 decades of frequency, > it would be academically fun to use a lot of spectrum to power my LED. > > I recall a project in Popular Electronics magazine where they > rectified a bunch of the AM spectrum to power a 1-transistor amplifier > to gain up one of the stations and drive a loudspeaker. Cute. > >> >> Basically the normal antique antenna circuit, >> Slide in a ferroxcube rod and you can tune it with that if it is AM medium wave, no antenna needed. >> >> >> LEDs also work great on higher frequencies, I had a LED on my GPA 27 MHz CB antenna output once >> and it would light up when the neighbor across the street transmitted, >> Or something like this: >> http://panteltje.nl/pub/testing_the_20_meter_inductive_loop_antenna_IMG_4536.JPG > > I tested one LED that would make light as fast as I could drive and > measure it, about 2 ns in my case. I think some other LEDs are slow > and have high capacitance. >That's potentially pretty useful, if it's not super expensive. What part was it? Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●March 13, 20232023-03-13
On Mon, 13 Mar 2023 17:15:41 GMT, Jan Panteltje <alien@comet.invalid> wrote:>On a sunny day (Mon, 13 Mar 2023 08:11:32 -0700) it happened John Larkin ><jlarkin@highlandSNIPMEtechnology.com> wrote in ><3reu0i959g26722rhbrp97baaqvingl0r4@4ax.com>: > >>On Mon, 13 Mar 2023 06:12:48 GMT, Jan Panteltje <alien@comet.invalid> >>wrote: >> >>>On a sunny day (Sun, 12 Mar 2023 20:34:46 -0000 (UTC)) it happened Mike Monett >>>VE3BTI <spamme@not.com> wrote in <XnsAFC5A8A94531Didtokenpost@88.198.57.247>: >>> >>>>Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>> >>>>> Or failing that, a regular low-barrier Schottky detector and a Joule >>>>> Thief to drive the LED. >>>>> >>>>> Might be fun making a Joule Thief out of a depletion pHEMT. ;) >>>>> >>>>> Cheers >>>>> >>>>> Phil Hobbs >>>> >>>>Need about 1V at some current >>>> >>>>Diodes Inc. ZXSC310E5 >>>> >>>>https://octopart.com/search?q=ZXSC310E5¤cy=USD&specs=0 >>>> >>>>or >>>> >>>>2 X 2N3904 >>>>https://www.edn.com/single-cell-lights-any-led/ >>>> >>>>or >>>> >>>>BC550C, 2N2222, BYV1030 >>>> >>>>https://www.electronicdesign.com/technologies/leds/article/21802105/ledstri >>>>ng-driver-operates-from-single-cell >>> >>>Yes, but mine runs from a simple thermocouple : >>> http://panteltje.nl/pub/lighting_a_LED_with_a_candle_IMG_3604.GIF >>> >>> JFET (you only need 1 for a LED). >>> >>>In the case of John Larkin's radio tower we need to know the frequency. >>>In this circuit you can get a lot of voltage gain like this: >>> >>>\ / antenna >>> | >>> | tunable core >>> | --------------- >>> | || | | | >>> | || ( |a |k >>> ) || ( LED1 LED2 >>> | || ( |k |a >>> | | | | >>> |-------------------- >>> | >>>/// >>>GND >> >> >>Yes. With RF from an antenna, impedance matching is easy. But a >>schottky diode or two might still help. >> >>Given my case, 22 megawatts spread over about 4 decades of frequency, >>it would be academically fun to use a lot of spectrum to power my LED. > >Well, that is almost always a hit for some length of wire :-) > >Did you ever try a LED on a 1/2 wave antenna? this is the type of CB antenna I used: > https://moonrakeronline.com/eu/venom-gpa-1-2-wave-base-antenna >The bandwidth is really small, only about 2 MHz, you can fine tune SWR with the length... >It is 50 Ohms out, has a matching transformer inside: > https://pe4bas.blogspot.com/2014/12/whats-inside-old-gpa-27-12.html >You can make your own for any other frequency (length). >Need to know the frequency very precisely. > >The loop antenna has even smaller bandwidth: > https://panteltje.nl/pub/testing_the_20_meter_inductive_loop_antenna_IMG_4536.JPG > https://panteltje.nl/pub/testing_the_20_meter_inductive_loop_antenna_dunno_IMG_4537.JPG > >Must have been > 1.5V pp for the LED to glow brightly.... :-) >I asked my neighbor how many watts he was putting out, but he kept that a secret >there is a legal limit on the amount of watts you can use here for CB transmission. > >Else just a RF inductor to ground with LED in parallel, any length of wire (depending on frequency)? > > > >>I recall a project in Popular Electronics magazine where they >>rectified a bunch of the AM spectrum to power a 1-transistor amplifier >>to gain up one of the stations and drive a loudspeaker. Cute. >> >>> >>>Basically the normal antique antenna circuit, >>>Slide in a ferroxcube rod and you can tune it with that if it is AM medium wave, no antenna needed. >>> >>> >>>LEDs also work great on higher frequencies, I had a LED on my GPA 27 MHz CB antenna output once >>>and it would light up when the neighbor across the street transmitted, >>>Or something like this: >>> http://panteltje.nl/pub/testing_the_20_meter_inductive_loop_antenna_IMG_4536.JPG >> >>I tested one LED that would make light as fast as I could drive and >>measure it, about 2 ns in my case. I think some other LEDs are slow >>and have high capacitance. > >27 MHz was a cheap LED from local shop I think. >I now have a nice assortment of different colors and 2 sizes from ebay, something like this: > https://www.ebay.com/itm/385132659452 >200 for $8.96 > > >So, now I am posting this from the Raspberry Pi4 8 GB with a new compiled NewsFleX usenet reader I wrote. >(else I used the laptop). >Cut and paste is a bit easier that way, else I have to ssh to the other thing all the time. >Tried that Pi4 thing yet?I fired it up and got the home screen. That's all so far. I'd hire some programmers to do the real work. I prefer architecture and hardware design lately. I ordered a Pi 400, the keyboard with a Pi inside. That could be our development system. I'm thinking of doing a PCB that would plug into it and have a ribbon cable that runs to our product boards, for debug access and power supply monitoring and such. We could have a dozen such dev systems, they would be so cheap. I'm still at the architecture stage of a new product line and it's worth thinking for a while to get things right.>Now also have Apache webserver running on it (to test website things before I upload i). > >I see I need to install ispell spellchecker on this Pi4 now.... just did (apt-get install ispell), but no go: > Can't open /usr/lib/ispell/english.hash > >So sorry for any typos :-)No need to be prissy about typing and spelling, as long as people can understand your intent.
Reply by ●March 13, 20232023-03-13
Mike Monett VE3BTI <spamme@not.com> wrote:>> (First search result for "joule thief jfet".) >> >> Cheers >> >> Phil Hobbs > > Wow! I gotta build one. What is the core? Is it critical, or just about > anything will do? > > The jfet is more difficult. How about a chopper?1. explore different configurations to find the lowest starting voltage Oscillator with super low supply voltage http://www.dicks-website.eu/fetosc/enindex.htm 2. typical low voltage JT do not deliver any power Low voltage Joule thief - exotic transistors? https://www.eevblog.com/forum/projects/low-voltage-joule-thief-exotic- transistors/ 2A. The LTC3108, available in either a 3 mm � 4 mm � 0.75 mm 12-pin DFN or 16-pin SSOP package, solves the energy harvesting problem for ultra-low input voltage applications. It provides a compact, simple, highly integrated monolithic power management solution for operation from input voltages as low as 20 mV. This unique capability enables it to power wireless sensors from a thermoelectric generator (TEG), harvesting energy from temperature differentials (?T) as small as 1�C. Using a small (6 mm � 6 mm), off-the-shelf step-up transformer and a handful of low cost capacitors, it provides the regulated output voltages necessary for powering today�s wireless sensor electronics. 3. this ic harvests energy from thermoelectric generators Ultra-Low Voltage Energy Harvester Uses Thermoelectric Generator for Battery-Free Wireless Sensors https://www.digikey.com/en/articles/ultra-low-voltage-energy-harvester- uses-thermoelectric-generator-for-battery-free-wireless-sensors https://octopart.com/search?q=LTC3108¤cy=USD&specs=0 -- MRM
Reply by ●March 13, 20232023-03-13
On 2023-03-13 14:26, Mike Monett VE3BTI wrote:> Mike Monett VE3BTI <spamme@not.com> wrote: > >>> (First search result for "joule thief jfet".) >>> >>> Cheers >>> >>> Phil Hobbs >> >> Wow! I gotta build one. What is the core? Is it critical, or just about >> anything will do? >> >> The jfet is more difficult. How about a chopper? > > 1. explore different configurations to find the lowest starting voltage > > Oscillator with super low supply voltage > http://www.dicks-website.eu/fetosc/enindex.htm > > 2. typical low voltage JT do not deliver any power > > Low voltage Joule thief - exotic transistors? > https://www.eevblog.com/forum/projects/low-voltage-joule-thief-exotic- > transistors/ > > 2A. The LTC3108, available in either a 3 mm × 4 mm × 0.75 mm 12-pin DFN or > 16-pin SSOP package, solves the energy harvesting problem for ultra-low > input voltage applications. It provides a compact, simple, highly > integrated monolithic power management solution for operation from input > voltages as low as 20 mV. This unique capability enables it to power > wireless sensors from a thermoelectric generator (TEG), harvesting energy > from temperature differentials (?T) as small as 1°C. Using a small (6 mm × > 6 mm), off-the-shelf step-up transformer and a handful of low cost > capacitors, it provides the regulated output voltages necessary for > powering today’s wireless sensor electronics. > > 3. this ic harvests energy from thermoelectric generators > > Ultra-Low Voltage Energy Harvester Uses Thermoelectric Generator for > Battery-Free Wireless Sensors > > https://www.digikey.com/en/articles/ultra-low-voltage-energy-harvester- > uses-thermoelectric-generator-for-battery-free-wireless-sensors > > https://octopart.com/search?q=LTC3108¤cy=USD&specs=0 > > >Some years ago I worked with a medium-sized defense contractor on a proposal to use IR antennas to scavenge power from the temperature difference between the inside and outside of a soldier's shirt. The idea was to power a short-burst radio beacon that would keep working until the temperature difference went away. :( A bit macabre, but potentially lifesaving. The feasibility calculation looked pretty promising--a pity it didn't get funded. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●March 13, 20232023-03-13
On Sunday, March 12, 2023 at 11:21:48 PM UTC-7, Jan Panteltje wrote:> On a sunny day (Sun, 12 Mar 2023 20:34:46 -0000 (UTC)) it happened Mike Monett > VE3BTI <spa...@not.com> wrote in <XnsAFC5A8A945...@88.198.57.247>:> >https://www.electronicdesign.com/technologies/leds/article/21802105/ledstri > >ng-driver-operates-from-single-cell > Yes, but mine runs from a simple thermocouple : > http://panteltje.nl/pub/lighting_a_LED_with_a_candle_IMG_3604.GIF > > JFET (you only need 1 for a LED).It's also possible nowadays to get a MOSFET instead of a JFET that has a good zero-volt threshold, from ALD... and they make prebuilt circuits for this DC/DC convert function, too <https://www.aldinc.com/ald_ehlvbooster.php>
Reply by ●March 13, 20232023-03-13
On Mon, 13 Mar 2023 13:48:46 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 2023-03-13 11:11, John Larkin wrote: >> On Mon, 13 Mar 2023 06:12:48 GMT, Jan Panteltje <alien@comet.invalid> >> wrote: >> >>> On a sunny day (Sun, 12 Mar 2023 20:34:46 -0000 (UTC)) it happened Mike Monett >>> VE3BTI <spamme@not.com> wrote in <XnsAFC5A8A94531Didtokenpost@88.198.57.247>: >>> >>>> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>> >>>>> Or failing that, a regular low-barrier Schottky detector and a Joule >>>>> Thief to drive the LED. >>>>> >>>>> Might be fun making a Joule Thief out of a depletion pHEMT. ;) >>>>> >>>>> Cheers >>>>> >>>>> Phil Hobbs >>>> >>>> Need about 1V at some current >>>> >>>> Diodes Inc. ZXSC310E5 >>>> >>>> https://octopart.com/search?q=ZXSC310E5¤cy=USD&specs=0 >>>> >>>> or >>>> >>>> 2 X 2N3904 >>>> https://www.edn.com/single-cell-lights-any-led/ >>>> >>>> or >>>> >>>> BC550C, 2N2222, BYV1030 >>>> >>>> https://www.electronicdesign.com/technologies/leds/article/21802105/ledstri >>>> ng-driver-operates-from-single-cell >>> >>> Yes, but mine runs from a simple thermocouple : >>> http://panteltje.nl/pub/lighting_a_LED_with_a_candle_IMG_3604.GIF >>> >>> JFET (you only need 1 for a LED). >>> >>> In the case of John Larkin's radio tower we need to know the frequency. >>> In this circuit you can get a lot of voltage gain like this: >>> >>> \ / antenna >>> | >>> | tunable core >>> | --------------- >>> | || | | | >>> | || ( |a |k >>> ) || ( LED1 LED2 >>> | || ( |k |a >>> | | | | >>> |-------------------- >>> | >>> /// >>> GND >> >> >> Yes. With RF from an antenna, impedance matching is easy. But a >> schottky diode or two might still help. >> >> Given my case, 22 megawatts spread over about 4 decades of frequency, >> it would be academically fun to use a lot of spectrum to power my LED. >> >> I recall a project in Popular Electronics magazine where they >> rectified a bunch of the AM spectrum to power a 1-transistor amplifier >> to gain up one of the stations and drive a loudspeaker. Cute. >> >>> >>> Basically the normal antique antenna circuit, >>> Slide in a ferroxcube rod and you can tune it with that if it is AM medium wave, no antenna needed. >>> >>> >>> LEDs also work great on higher frequencies, I had a LED on my GPA 27 MHz CB antenna output once >>> and it would light up when the neighbor across the street transmitted, >>> Or something like this: >>> http://panteltje.nl/pub/testing_the_20_meter_inductive_loop_antenna_IMG_4536.JPG >> >> I tested one LED that would make light as fast as I could drive and >> measure it, about 2 ns in my case. I think some other LEDs are slow >> and have high capacitance. >> >That's potentially pretty useful, if it's not super expensive. What >part was it? > >Cheers > >Phil HobbsSorry, can't remember now.
Reply by ●March 13, 20232023-03-13
On 3/13/23 14:26, Mike Monett VE3BTI wrote:> Mike Monett VE3BTI <spamme@not.com> wrote: > >>> (First search result for "joule thief jfet".) >>> >>> Cheers >>> >>> Phil Hobbs >> >> Wow! I gotta build one. What is the core? Is it critical, or just about >> anything will do? >> >> The jfet is more difficult. How about a chopper? > > 1. explore different configurations to find the lowest starting voltage > > Oscillator with super low supply voltage > http://www.dicks-website.eu/fetosc/enindex.htm > > 2. typical low voltage JT do not deliver any power > > Low voltage Joule thief - exotic transistors? > https://www.eevblog.com/forum/projects/low-voltage-joule-thief-exotic- > transistors/ > > 2A. The LTC3108, available in either a 3 mm × 4 mm × 0.75 mm 12-pin DFN or > 16-pin SSOP package, solves the energy harvesting problem for ultra-low > input voltage applications. It provides a compact, simple, highly > integrated monolithic power management solution for operation from input > voltages as low as 20 mV. This unique capability enables it to power > wireless sensors from a thermoelectric generator (TEG), harvesting energy > from temperature differentials (?T) as small as 1°C. Using a small (6 mm × > 6 mm), off-the-shelf step-up transformer and a handful of low cost > capacitors, it provides the regulated output voltages necessary for > powering today’s wireless sensor electronics. > > 3. this ic harvests energy from thermoelectric generators > > Ultra-Low Voltage Energy Harvester Uses Thermoelectric Generator for > Battery-Free Wireless Sensors > > https://www.digikey.com/en/articles/ultra-low-voltage-energy-harvester- > uses-thermoelectric-generator-for-battery-free-wireless-sensors > > https://octopart.com/search?q=LTC3108¤cy=USD&specs=0The voltage of a thermocouple junction is determined by the properties of the two materials and the temperature difference, but what determines how much current is available? Just wondering if it's the cross-sectional area of the junction, and if so which is better for a given amount of thermocouple material: lots of small junctions in series to give higher voltage but very small current (standard thermopile), or a small number of high-area junctions feeding a Joule thief circuit? -- Regards, Carl
Reply by ●March 13, 20232023-03-13
On Mon, 13 Mar 2023 18:19:30 -0400, Carl <carl.ijamesxx@yyverizon.net> wrote:>On 3/13/23 14:26, Mike Monett VE3BTI wrote: >> Mike Monett VE3BTI <spamme@not.com> wrote: >> >>>> (First search result for "joule thief jfet".) >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> Wow! I gotta build one. What is the core? Is it critical, or just about >>> anything will do? >>> >>> The jfet is more difficult. How about a chopper? >> >> 1. explore different configurations to find the lowest starting voltage >> >> Oscillator with super low supply voltage >> http://www.dicks-website.eu/fetosc/enindex.htm >> >> 2. typical low voltage JT do not deliver any power >> >> Low voltage Joule thief - exotic transistors? >> https://www.eevblog.com/forum/projects/low-voltage-joule-thief-exotic- >> transistors/ >> >> 2A. The LTC3108, available in either a 3 mm � 4 mm � 0.75 mm 12-pin DFN or >> 16-pin SSOP package, solves the energy harvesting problem for ultra-low >> input voltage applications. It provides a compact, simple, highly >> integrated monolithic power management solution for operation from input >> voltages as low as 20 mV. This unique capability enables it to power >> wireless sensors from a thermoelectric generator (TEG), harvesting energy >> from temperature differentials (?T) as small as 1�C. Using a small (6 mm � >> 6 mm), off-the-shelf step-up transformer and a handful of low cost >> capacitors, it provides the regulated output voltages necessary for >> powering today�s wireless sensor electronics. >> >> 3. this ic harvests energy from thermoelectric generators >> >> Ultra-Low Voltage Energy Harvester Uses Thermoelectric Generator for >> Battery-Free Wireless Sensors >> >> https://www.digikey.com/en/articles/ultra-low-voltage-energy-harvester- >> uses-thermoelectric-generator-for-battery-free-wireless-sensors >> >> https://octopart.com/search?q=LTC3108¤cy=USD&specs=0 > >The voltage of a thermocouple junction is determined by the properties >of the two materials and the temperature difference,Not exactly, but close. but what determines>how much current is available?The loop resistance. T/C wire tends to have a lot of resistance compared to copper. Fatter and shorter wire allows more current but conducts more heat so is harder to force a temperature difference across.>Just wondering if it's the >cross-sectional area of the junction, and if so which is better for a >given amount of thermocouple material: lots of small junctions in >series to give higher voltage but very small current (standard >thermopile), or a small number of high-area junctions feeding a Joule >thief circuit?Probably lots of little ones in series. That's easier to use.
