When did supercapacitors start being used in consumer products? - Page 1
Forum section: electronics / general

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 05, 2024, 02:52:32 am
content: I recently bought a 1984 VCR, for fun, and of course I took it apart. It's the type with the channels on the tuner dialed in with cute little trimmers on top. So no digital memory required.Inside, I was surprised to immediately see what appears to be a supercap.I figure it's to recall the recording program setting.I didn't expect a supercap used in consumer stuff from '84.(If so... why can't 21st century stoves, microwaves, and fridges, etc recall their dumb settings when a single cycle of AC goes missing?)

author: Kim Christensen
author_rank: Super Contributor
timestamp: January 05, 2024, 03:33:28 am
content: What's the capacitance value of that one?

author: Shonky
author_rank: Frequent Contributor
timestamp: January 05, 2024, 03:37:33 am
content: Don't need a supercap to store settings. Flash or EEPROM can easily cover basic things that a typical appliance might use with some wear levelling if necessary. It's just they can't be bothered and realistically for many it's a not issue these days as power grids are pretty reliable.Where you *do* need a backup power source is to run an RTC.

author: ejeffrey
author_rank: Super Contributor
timestamp: January 05, 2024, 04:01:17 am
content: A lithium coin cell could power an rtc for over a decade. But yeah, manifacturers can't be bothered.

author: helius
author_rank: Super Contributor
timestamp: January 05, 2024, 04:21:44 am
content: I have seen supercaps inside several 1980s stereo receivers. I think as soon as CMOS SRAM and microcontrollers were available, supercapacitors were designed to complement them. The electric-double-layer technology would already have existed as a research material in the lab and this would be its first major application.A supercap of the size shown is around 1 farad at 2.5 V.

author: Andy Chee
author_rank: Super Contributor
timestamp: January 05, 2024, 04:31:51 am
content: Quote from: Shonky on January 05, 2024, 03:37:33 amThis VCR was built in an era when 4-bit microcontrollers were "a thing" (the chip in the image is a 4-bit micro). In other words, flash and eeprom were an expensive luxury, they couldn't even afford 4 extra bits!The supercap retaining power to the 4-bit micro was evidently a cheaper way to retain memory settings.

author: Berni
author_rank: Super Contributor
timestamp: January 05, 2024, 06:45:10 am
content: The reason why most appliances have no clock backup battery/cap is that they are built down to a price.Consumer appliances are in a viscous race to the bottom in price. The volumes are huge and competition is fierce. So when it comes to the electronics parts they will switch to a different resistor manufacturer if that means they can save 1 cent per board. Since having backup power would cost a few cents at least means that feature gets axed early on already. Not only does a supercap cost money, but the cheap little 2 cent MCU inside does not have any precision oscillator, nor low power features.Id gladly pay 50% more for a appliance that is less cost cut down, but there is no easy way to distinguish appliances that actually had more expense put into a high quality BOM or have just been marked up more for profit (because it is a famous brand or popular model or something)

author: SeanB
author_rank: Super Contributor
timestamp: January 05, 2024, 07:54:37 am
content: Yes will add that, even in 1984, double layer boards were cheap, but, because they have to be made, at least at that time, with FR4 woven laminates, you see that even now you have a lot of SRBP board, single sided. Have seen a board in a copier, that had 244 jumper wire links on it, just to avoid going to double sided, because the board, around the size of your hand, had 20 connectors on it, and a single row of resistors, a few diodes, and a single electrolytic capacitor on it, but having an auto insertion machine put in 244 links, in 4 sizes, was still cheaper than making it out of FR4 and double sided.Currently look at any remote control, thin SRBP board, which is not drilled, but actually punched to shape, and also the holes are punched as well. Then a green silkscreen layer, followed by a carbon layer for the links, and another silkscreen over that. Done to minimise cost to the max.As to supercapacitors, those were common, cheaper than rechargeable batteries, and also used as no discharge in shipping, as they only got charged when the consumer plugged it in, so no sahipping risk due to having stored power in a battery, which is still a thing you need to declare in shipping. Flat capacitor is not an extra risk, but a pack of AAA cells in a remote means a higher insurance rate.

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 05, 2024, 08:33:17 am
content: Quote from: Berni on January 05, 2024, 06:45:10 amThat's why teardowns are useful.

author: amyk
author_rank: Super Contributor
timestamp: January 05, 2024, 10:31:07 am
content: https://en.wikipedia.org/wiki/Supercapacitor#HistoryQuoteTo answer your question directly: 1978.

author: 5U4GB
author_rank: Super Contributor
timestamp: January 05, 2024, 10:56:12 am
content: I was debugging an embedded device a few years ago with an MSP430 on it that had hung and for some reason I can't remember it wasn't possible to reset it. It's OK, we'll just pull the power and force a restart... why is it not shutting down... ah, that thing over there is an SMD supercap. OK, we could be waiting awhile.Given that it was pretty much instant-on I never figured out (other than assorted speculation) why they bothered to put a supercap in there.

author: Psi
author_rank: Super Contributor
timestamp: January 05, 2024, 11:05:52 am
content: Yeah, you see them from time to time in old gear.The main difference is their terrible internal resistance compared to any other capacitor type. It made them pretty much only usable for RTC or NVM battery backup.You can only draw ~few mA from them if that, verses being able to pull out 50A for 100ms on a modern supercap of similar size.

author: Shonky
author_rank: Frequent Contributor
timestamp: January 07, 2024, 06:15:09 am
content: Quote from: Andy Chee on January 05, 2024, 04:31:51 amThe question was why 21st century devices can't remember settings implying a supercap could do it.

author: andy2000
author_rank: Frequent Contributor
timestamp: January 07, 2024, 06:58:17 am
content: They were common by about 1985. Before that, they usually used a Ni-Cd cell if there was even a backup. Super capacitors do sometimes fail, particularly the ones made by Panasonic. The ones made by NEC were much more reliable, but were larger than the same value Panasonic.

author: Andy Chee
author_rank: Super Contributor
timestamp: January 07, 2024, 06:59:15 am
content: Quote from: Shonky on January 07, 2024, 06:15:09 amThe answer almost always comes down to cost, rather than any technological constraint.

author: Ranayna
author_rank: Super Contributor
timestamp: January 07, 2024, 01:49:45 pm
content: Quote from: Andy Chee on January 07, 2024, 06:59:15 amMost likely reason.Also, i addition to the super cap to store the settings, depending on what these settings actually are, you might need to implement a way to reset the device to factory default if they get corrupted somehow.

author: joeqsmith
author_rank: Super Contributor
timestamp: January 07, 2024, 09:39:04 pm
content: We started using them in the mid 80s, when ever NEC started to offer them. I think I still have a few of the early ones.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 08, 2024, 01:59:26 pm
content: Quote from: Shonky on January 05, 2024, 03:37:33 amIn 1980's, you didn't have those - so battery-backed SRAM was the usual way. They managed to build low-power SRAM so even small batteries lasted for years. Supercapacitors this early was news to me, too.BTW, battery-backed SRAM is still a thing, for example most STM32 MCUs have this feature. It's quite useful for some stuff, without having to think about erase/write times or endurance.

author: Halcyon
author_rank: Unknown
timestamp: January 08, 2024, 09:29:55 pm
content: Quote from: Alex Eisenhut on January 05, 2024, 02:52:32 amThis shits me about my oven (and it's not a cheap model/brand either).At least if you're going to have a product that forgets the time, have it fail to a known and predictable state. For example, my Sharp microwave defaults back to a scrolling Welcome/Demo message and after you use the product for the first time (but don't set the clock), it just shows a static "0" when not being used. This is sensible.My oven on the other hand starts flashing the time and starts counting again from 00:00, so that it's always showing the incorrect time until you manually reset it. I would rather the display be completely blank or just flash a decimal point or something.

author: coppice
author_rank: Super Contributor
timestamp: January 08, 2024, 09:39:35 pm
content: Quote from: joeqsmith on January 07, 2024, 09:39:04 pmNEC started offering modern style supercaps in the late 70s. I think their primary target market at their launch was backup which was just becoming a substantial market at that point. This was before EEPROM was really viable for cheap backup.

author: Shonky
author_rank: Frequent Contributor
timestamp: January 09, 2024, 01:44:24 am
content: Quote from: Siwastaja on January 08, 2024, 01:59:26 pmAs per the original post that people don't seem to have read (or my reply):Quote

author: Siwastaja
author_rank: Super Contributor
timestamp: January 09, 2024, 11:34:47 am
content: Quote from: Shonky on January 09, 2024, 01:44:24 amWe were so amazed at the 1980's tech we missed the question. The answer is: they can, but the products are penny-pinched to the last drop, because the design teams are led by sadists who want to offer poor user experience. The cost of using a microcontroller with built-in EEPROM plus NRE cost to program it would be a few cents per microwave oven, but that leaves the clock reset problem. Adding a 32768Hz crystal + a supercap so that clock keeps the time during short outages would cost more, but still far below $1 (you would not need EEPROM, then, settings would be stored in battery-backed SRAM). Someone decided these few dozen cents are not worth spending.