SuperCap on Horizon?

[+Ksarul]

When looking at germanium diodes, the Russian D9K is a drop-in replacement for the 1N34A, and based on my experiences with them in Horizon 4000Bs, they are always on-spec.

[Tursi]

Yeah, those readings are lower than I expected, so I looked up the datasheets on the RAM chips, and it checks out.

 

Then I was surprised the supercap runtime was lower than I expected with that lower current draw

 

[+acadiel]

Yeah, those readings are lower than I expected, so I looked up the datasheets on the RAM chips, and it checks out.
 
Then I was surprised the supercap runtime was lower than I expected with that lower current draw
 

Yeah, but it’s definitely good for retaining info for something that’s plugged in most of the time. I figured the duration ought to be a week or more.

But, they do keep improving these, so who know. We might have some 50F models out that take the same space eventually.

[+OLD CS1]

Why just one super-cap?

[+acadiel]

Also, I don't know how legit they are, but you can get 50F ones:

https://www.ebay.com/itm/252080792512?hash=item3ab12fa3c0:g:tZ4AAOSwTo1c1LBW

 

But most of the higher ones are only 2.7V.  That would work for backing up the SRAM, which I think can go down to 2.2V.  No diode would be in the circuit, but we'd have to put something in the circuit to limit the voltage.

 

That's a whopping 16 days according to the calculator

[+acadiel]

Just now, OLD CS1 said:

Why just one super-cap?

Sure, let's throw up a bank of them!  "PEB Supercap card" - Throw 20 of those 50F bad boys up there and you'd get 800 days of backup!

[+OLD CS1]

Just now, acadiel said:

Sure, let's throw up a bank of them!  "PEB Supercap card" - Throw 20 of those 50F bad boys up there and you'd get 800 days of backup!

If we have the room for it.  I mean, I just watched a guy who has a shed full of battery packs for his solar system made from thousands of 18650s.

 

You said they can charge instantly with no limiting resister, right?  At what point do we risk drawing too much with inrush current?

[+acadiel]

1 minute ago, OLD CS1 said:

If we have the room for it.  I mean, I just watched a guy who has a shed full of battery packs for his solar system made from thousands of 18650s.

 

You said they can charge instantly with no limiting resister, right?  At what point do we risk drawing too much with inrush current?

I haven't looked up the methods of limiting the initial charging yet.  I know the NiCd had 300 ohm resistors on both ends to help with that.  Don't know what's needed for a supercap.

[+acadiel]

10 hours ago, Ksarul said:

When looking at germanium diodes, the Russian D9K is a drop-in replacement for the 1N34A, and based on my experiences with them in Horizon 4000Bs, they are always on-spec.

спасибо товарищ!
 

[Tursi]

4 hours ago, OLD CS1 said:

You said they can charge instantly with no limiting resister, right?  At what point do we risk drawing too much with inrush current?

Early enough that you should put a resistor on them.  Doesn't have to be too big.

 

[+OLD CS1]

10 minutes ago, Tursi said:

Early enough that you should put a resistor on them.  Doesn't have to be too big.

I always prefer a limiting resistor on a normal cap across a input power rail, anywhere from 220ohm to 1k.  But he did say "IMHO, it’ll recharge instantly and doesn’t need any kind of resistor, diode, etc."  I was not sure if that was simple opinion or based upon spec.

[Tursi]

56 minutes ago, OLD CS1 said:

I always prefer a limiting resistor on a normal cap across a input power rail, anywhere from 220ohm to 1k.  But he did say "IMHO, it’ll recharge instantly and doesn’t need any kind of resistor, diode, etc."  I was not sure if that was simple opinion or based upon spec.

Yeah.. I didn't bother with one using a .1F Supercap on the Minimemory, but I didn't know about inrush then. I'd certainly be concerned with multiple caps on a RAMdisk with all the RAM chips to keep alive

 

[+TheBF]

5 hours ago, acadiel said:

спасибо товарищ!
 

I just freaked myself out because it a second but I read this from my little bit of Russian study.

Spacibo tovarich.  

[sparkdrummer]

The Rave 99 RAM disks use super caps. 

Edited January 25 by sparkdrummer

[+FALCOR4]

On 1/24/2022 at 8:38 PM, acadiel said:

1N914? I looked at those and the specs didn’t look too good on them, so I decided to use the 1N4001 instead. The voltage drop shouldn’t be an issue because it can go down to 2.2 before it gets to be an issue.

That works!  I did a curve trace a year or so ago with a 1N34A and an NTE109 just for kicks.  The downside to germanium diodes, though, is that the leakage current is generally higher than silicon.

1N34A_NTE109 Comparison.pdf