Hello=) forgot to tell you some things

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Livio
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Hello=) forgot to tell you some things

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About those lil crypto MCUs are you able to use EEPROM to store some "calculated" data to avoid too much CPU usage like some guys do with thermistors readings?
And about that joule thief I've saw that a battery can be made of aluminum foil, paper with distilled water and graphite. I've tested a raw one I've made and has 0.7VDC and 700uA if shorted. It's ridiculous but maybe more cells like that together can power that blinker and seems it's able to recover fine from shorts giving back full power after a minute.
By the way aluminum-copper gives a bit more power but copper can release carbonate and stop conducting.
Aluminum should turn into harmful hydroxide and graphite probably will not change over time.
Hard graphite is better since soft graphite can have some wax inside.
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Re: Hello=) forgot to tell you some things

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Livio wrote: 05 Jan 2020, 23:32About those lil crypto MCUs are you able to use EEPROM to store some "calculated" data to avoid too much CPU usage like some guys do with thermistors readings?
I guess its possible to make array with "calibration data" and therefore ADC reading -> actual value would be mere 1 lookup, like result = cal_data[adc_sample].
The disadvantages would be:
- Need to perform calibration and flash its result.
- Fairly large table in flash/eeprom (assuming eeprom accessible like array or you're willing to reload that to RAM, wasting plenty of RAM).
And about that joule thief I've saw that a battery can be made of aluminum foil, paper with distilled water and graphite.
Guess distilled water isn't best choice, you likely want some salts or acids as electrolyte. Guess you had some residual salts or something on materials themselves so it did the trick.
I've tested a raw one I've made and has 0.7VDC and 700uA if shorted. It's ridiculous but maybe more cells like that together can power that blinker and seems it's able to recover fine from shorts giving back full power after a minute.
I can imagine blinker would start up from this "as is", 700mV should be ok, esp if you put capacitor parallel to battery. Say 2.2uF cercap holds enough power for few flashes in case of design I've mentioned, 1000uF would blink for a while without any battery at all. Though 2x of that sounds more adequate.
By the way aluminum-copper gives a bit more power but copper can release carbonate and stop conducting.
Aluminum should turn into harmful hydroxide and graphite probably will not change over time.
Sure, graphite is inert. So only one electrode would be spent. Just like zinc spent in more typical batteries while graphite used to conduct current. That also makes graphite quite useful for experiments with electrolisys, etc - unless I'm nut it wouldn't normally give byproducts, only some gases that make electrolyte (e.g. 2H2O -> 2H2 + O2).
Hard graphite is better since soft graphite can have some wax inside.
Actually factory made cells usually feature some graphite.

p.s. btw, what your wildest guess would be be about lowest startup voltage of joule-thief like designs? :)
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Re: Hello=) forgot to tell you some things

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t3st3r wrote: 10 Feb 2020, 03:09

p.s. btw, what your wildest guess would be be about lowest startup voltage of joule-thief like designs? :)

Startup voltage is closely related to the base-emitter junction of the NPN transistor and those germanium transistors are quite expensive and rare today. So I've found a way to make it start up with voltage low as 350mV using inductors on both base and collector with a button that shorts base and emitter together. By pressing rapidly that button a quite high voltage will be generated and it will make the circuit start oscillating. However battery internal impedance may cause this to fail at some point. I've done those kind of tests with the lab power supply.

Another simple interesting circuit is the mosfet bidir shifter:
Image
From https://hackaday.com/2016/12/05/taking- ... -shifters/

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Re: Hello=) forgot to tell you some things

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Livio wrote: 23 Aug 2020, 12:51

Startup voltage is closely related to the base-emitter junction of the NPN transistor and those germanium transistors are quite expensive and rare today. So I've found a way to make it start up with voltage low as 350mV using inductors on both base and collector with a button that shorts base and emitter together.

I would be crappy mage if it would be as simple as that, no? :P. Well, somewhere, someday I've stumbled on funny patent ... its overall idea is quite simple: you can make oscillators out of normally-open devices, too! Like, say, some J-FETs. Some of these conduct some current even without bias. At which point bias isn't a problem anymore, right? So patent claims it can be as low as few dozens mV for self-start. It also listed improved versions where "better" MOSFET takes over once there is enough voltage since JFETs aren't terribly great as power switches. Still, starting from quite few millivolts... damn, impressive. Obviously it retains overall structure of joule thief.

By pressing rapidly that button a quite high voltage will be generated and it will make the circuit start oscillating. However battery internal impedance may cause this to fail at some point. I've done those kind of tests with the lab power supply.

Hmm, I've put ceramic capacitor parallel to battery in "perpetuum blinker" things I mentioned, so they can blink even if battery resistance gone nuts. But it implies low duty cycle.

Another simple interesting circuit is the mosfet bidir shifter:

Whoa, quite funny. Damn, philips site says it can't find that appnote anymore. Btw, there is also NON-INVERTING level shifter based on BJT. Though it isnt bidirectional but uses unorthodox transistor placement to achieve non-inverting level shifting.

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