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Author Topic: Harvesting electro-magnetic energy  (Read 1881 times)

Bertoa

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Harvesting electro-magnetic energy
« on: January 15, 2022, 04:39:34 PM »
This is a known way to harvest 24/7/365 energy from an antenna or in my case from the steelbase of a table. I wanted to check the amount of energy I can possible harvest between the table at the first floor and the ground pin. With 4 parts I made an circuit that charges in a day and a half a 10.000 microfarad electrolytic condensor to 7 Volt. Strange enough I could not measure any charge current with my multimeter, not one microAmp. Maybe I tap, beside electromagnetic energy, also ZPE, radiant and atmospheric energy; who knows? The speed of charging surprises me. I was also charging a supercap of 3 Farad and 2.7 Volt. This did not work out so well. Maybe the internal leaking current? 
I search now for an ultra low power circuit to flash (20 milisecond) a led once in an hour. Maybe people here can give me some advice.

 
 
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Bertoa

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Re: Harvesting electro-magnetic energy
« Reply #1 on: January 24, 2022, 02:21:15 PM »
The energy harvest circuit has now a 3 farad capacitor. It charges slow but constant. The TPL5111 module uses ultra low current about 600nA. The voltage range is from 1.8V to 5Volt It has a potmeter for a timer setting till 2 hours. This circuit runs at 2.5V and has a 100 milisecond LED blink every 5 minutes.The circuit uses the same amount of energy than it can harvest. With this ultra low power device you can use E-smog at a very small scale.
 
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gyulasun

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Re: Harvesting electro-magnetic energy
« Reply #2 on: January 24, 2022, 05:27:58 PM »
Hi Bertoa, 

The following circuit could also be driven by the energy harvest circuit, see here :  http://www.discovercircuits.com/DJ-Circuits/ac14fls.htm   

The mark / space ratio can be adjusted by replacing the 15 kOhm resistor (which is in series with the 1N4148 diode) with say 100 kOhm potmeter, while the frequency can be tuned by varying the 0.15 uF capacitor on Pin 1 of the 74AC14.   The average current consumption of the flasher circuit is around 120 uA with the given 4 ms ON time.

Perhaps there are further useful circuits shown in this link: http://www.discovercircuits.com/E/energy-harvesting.htm 

The TPL5111 is a useful integrated circuit too.   IF you happen to have old Germanium diodes like OA1154,  OA1161, OA5 1N34 and the like, then the forward voltage drop can be smaller than that of the Schottky types (if this change is worth doing, that is).   

Gyula
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Bertoa

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Re: Harvesting electro-magnetic energy
« Reply #3 on: January 25, 2022, 01:18:30 AM »
Thanks Gyula for your info. I know David Johnsons electronic circuits. He is one of the forerunners to design very low power circuits. In this days some modules have an ultra low own use. My 'covid' windowsill machines have a power consumption of a few micro amps.
120uA is a high average consumption, depending of the LED current. The used schottky diode's BAT85 has a forward voltage of 292mV, that's quite low. My statement here is that overunity is a fact in the micro- and nano watt world. It's a pity that the applicability is limited.
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