Memory Retention Caps

[Grubhead]

Are memory retention capacitors still commonly used in electronic circuits these days? Or have they found a better way of keeping memory circuits active when the mains is not on?
I am just wondering, because they used to cause all sorts of problems in VCR's and Radio station memory settings. Where you had to keep the power on Standby, or if the power went off all the stored radio station settings vanished.
I have a picture of one of the pesky little things.

[jjl]

Use of these supercaps to power an SRAM device for memory retention is rare these days.

For quite a few years, most consumer electronics equipment has used EEPROM or Flash to retain data across power cycles e.g. television channel settings etc. With many microcontrollers designed for such applications Flash memory is on-chip and hence is effectively free. Many of these devices have special high endurance areas of Flash that are good for 100,000 or so write accesses.

John

[camtechman]

Also used in cameras, especially Pentax, a regular failing part and Pentax couldn't keep up with spares stock.

['LIVEWIRE?']

Some car stereos also used 'memory back-up' capacitors similar to that shown. Others used Batteries of various types for the purpose, usually in cases where the radio was removable from it's housing (Blaupunkt called this feature 'Quick out') I still have a couple of mod. kits supplied by Blaupunkt, which were designed to ensure that the station settings, etc., were retained whilst the stereo was out of the car. From memory these kits contained a couple of resistors, maybe a zener diode, and a so-called 'supercap', similar to that illustrated. Pioneer (and maybe others) used coin cells (CR2025 or similar) in their removable stereos for this purpose.

[Graham G3ZVT]

Does anyone remember a German colour set, Grundig perhaps, that had a bank of special ultra low leakage caps in glass cases that stored the analogue settings for volume, brightness, contrast etc?

Or was that just a bad dream?

Graham.
G3ZVT

[Refugee]

I thought Grundig TVs had a battery holder in the cabinet floor that took normal disposable cells.

[Maarten]

Originally Posted by rambo1152

Or was that just a bad dream?

It could be both reality and a bad dream. If it was Grundig, they can't have used it for long (maybe it was a bad dream for them as well?) since I've never seen it (in any brand for that matter). I wouldn't put it past ITT/SEL either.

[dazzlevision]

Originally Posted by rambo1152

Or was that just a bad dream?

No, you are not dreaming! Not in glass cases, but the Grundig Supercolor model 6011TDGB, with red plastic cased "memory modules". I still have some.

[Richard_FM]

My parent's 1980s Philips TV started to lose the channel settings after about a decade. My Mum managed to get the technicians at the places she worked have a look at it.

The managed to sort it out, but after a year or 2 it started to lose them again.

[MotorBikeLes]

Yes, the Grundig 6010,6011 and 2222 each had three of these "memory cells". The later 2222 and 6022 had a little "chip" instead. Likewise the final "top of the range" NordMende hybrid sets used the same modules.
There was a neon bulb feeding a DC voltage to a storage capacitor, and an igfet transferring that voltage to the output. The DC voltage (pos or neg depending on whether say Vol up or Vol down. One tuned circuit of the remote provided the +volts, the other the -volts, fed thro a 15Mohm resistor. The striking voltage of the neon well exceeded by these supplies, but a permanently lighted neon tube external to the cell was there to help to excite the gas to ensure conduction in view of the very low current. There were manual up/down buttons on the set which connected permanent high pos and neg voltages, and these were prone to leakage, resulting in one function drifting to extreme position, high or low depending where the leak was sourced. Quite ingenious!
Les.

[greg_simons]

Ah happy days, anyone remember the gold caps that used to blow up in you face when they were soldered?.

[Maarten]

Originally Posted by Richard_FM

My parent's 1980s Philips TV started to lose the channel settings after about a decade. My Mum managed to get the technicians at the places she worked have a look at it.

The managed to sort it out, but after a year or 2 it started to lose them again.

Probably a faulty NiCd or NiMH battery.

[Richard_FM]

Yes at the time I thought it was something like this.

[boxdoctor]

Originally Posted by greg_simons

Ah happy days, anyone remember the gold caps that used to blow up in you face when they were soldered?.

Some of the earlier Technics electronic organs used 3 x "Gold Cap" ( I think they were actually called that) capacitors for memory back-up for all the panel settings when the organ was switched off. About 2 farad, and the size of a AAA cell if I remember correctly. They all eventually failed, and oozed a corrosive gunge onto the P.C.B. I always waggled them, and broke off the wires as a first step to removing them, as they were prone, as Greg says, to literally explode or at least menacingly fizz when brought into contact with a hot soldering iron.
Dreadful things! Luckily, they were not used in production for very long. Tony.