|
OK, so this isn't really micro power, but it's related if you power your circuits from a USB power bank. The Anker PowerCore Slim 10000 has low quiescent power draw. Specifically, the cheap $16, 3 port model (USB-C input only, micro USB input, standard USB A output). You need to pull a current pulse of 100-150 mA every <120 seconds to keep the power bank turned on. But if you do this, it will run for over 2 weeks. Most power banks have atrocious idle power draw, because it doesn't matter for their standard use case. But this specific Anker model is cheap and good, and the engineers did pay attention to quiescent draw. e: Hmm, maybe you could operate off a supercap and wake up the power bank every hour/day/week for a minute to recharge it? That could extend the time to months maybe. I should try this! ryanrs fucked around with this message at 17:23 on Apr 14, 2024 |
#
¿
Apr 14, 2024 17:19
|
|
|
|
| # ¿ May 9, 2024 06:11 |
|
|
ryanrs posted:e: Hmm, maybe you could operate off a supercap and wake up the power bank every hour/day/week for a minute to recharge it? That could extend the time to months maybe. I should try this! So this was the idea: 5V USB in, 3.3V out to your circuit. USB > linear-charger > super-cap > linear-regulator > 3.3V When the supercap voltage hits 3.6V, wake up the USB power bank by simulating a plug event, charge up the supercap, then disconnect the power bank and let it turn itself off. Efficiency will be identical to a 5V to 3.3V linear regulator. All the power savings come from using the power bank in burst mode. Quiescent current will be under 100uA, hopefully significantly so. But I'm not going to expend great effort on reducing it to <10uA, because there is a more efficient version of this design that uses a switching regulator to charge and discharge the super cap. This linear version is designed to be simple. With a 3F super cap and a 1mA load, it will turn on the power bank every ~1 hr. Goal is 3-12 months runtime at 1mA using a $20 Anker USB power bank. I really, really wanted this thing to be based on a 555, but even the CMOS versions use 200uA. It's that 3 resistor chain and the Control pin. I think that circuit architecture makes ultra low power fundamentally difficult. So instead I have to use a discrete comparator and 74LVC74 flip flop. But I really wanted to use a 555.
|
|
#
¿
Apr 15, 2024 06:31
|
|
|
Extra complexity is free until you have to start releasing security patches. For example, I've been looking at how to IoT-ize my various microcontroller projects. Until now, they've all talked over proprietary wireless or USB, where the security threat wasn't such an issue. But once wifi and ethernet is in play, I need to actually think about proper encrypted protocols. For my USB/Internet protocol translators, I decided to use second-hand wifi access points running OpenWRT. They are plentiful and dirt cheap on ebay / craigslist / facebook. Many models have USB ports. And if it runs vanilla OpenWRT, then I am likely to receive security patches and improvements for a long time.
|
|
#
¿
Apr 16, 2024 19:01
|
|
|
multi-core superscalar microcontrollers, lol
|
|
#
¿
Apr 17, 2024 03:04
|
|
|
PJRC Teensy took it too far, imo. I had to abandon them because their boards run at 600 MHz and use 100 mA. Low power consumption was a low priority for development, so out of the box, that's all you get. It's totally unworkable for anything that isn't plugged in.
|
|
#
¿
Apr 17, 2024 04:59
|
|
|
USB Super Capacitor  BOM highlights: LTC3127 Buck-boost switcher MIC841L comparators + reference SIL2308 Dual n-/p-ch mosfet Turns out the switching version is smaller and has fewer components, although one of them is an expensive Analog Devices switching regulator. The MIC841 is a cool little comparator chip. It has all the guts of a 555, except the resistor divider. It even includes the flip-flop! This circuit is really just a big relaxation oscillator. When the supercap hits 3.7V, the MIC841 turns on the USB power bank and starts charging the cap. When it hits 5.1V, it turns off the charger. It does this on 3uA, 1/100th the power of a CMOS 555. Enough signals are brought out to pins to let you change the threshold voltages, explicitly request USB power, and get notified when the USB power bank is dead, but the supercap still has a little juice.
|
|
#
¿
Apr 17, 2024 06:42
|
|
|
Today in the lab there was a loud BANG and the smell of burning wood. I was across the room when it happened, so I didn't see which device it came from. The smell was strongest around my Tek scope (no!), but the smell was more like the building was smoldering, not a modern(-ish) digital scope on fire. Nope! A capacitor had blown up in my 30+ year old HP 6236B triple output power supply. It was a 0.1uF RIFA cap across the AC main. It smelled like burning wood because it's a paper capacitor. I will be replacing it with a modern metallized polypropylene film X2 cap, even though Digikey still sells paper RIFA caps.
|
|
#
¿
Apr 21, 2024 06:13
|
|
|
So why are RIFA caps still being manufactured? What's so good about them to offset the large physical size, high price, and explosive failures?
|
|
#
¿
Apr 21, 2024 17:41
|
|
|
quote:[Senator Collins:] Well, there are … regulations governing the materials they can be made of
|
|
#
¿
Apr 25, 2024 08:25
|
|
|
|
| # ¿ May 9, 2024 06:11 |
|
|
USB-C stuff negotiates voltage levels and poo poo before turning on the juice, so that should work fine. USB-C laptop charger powering a desk lamp is A-OK.
|
|
#
¿
Apr 27, 2024 23:16
|
|