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My first (hand assembled) computer - 486DX2-80

modem7 said:
If you later need to move back to an 'internal' battery, then I am pretty sure that you would need to put the jumper back on.
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Yes you do. I'm pretty certain the jumper connects the positive leg of the 'internal' battery to the positive side of the clock/bios circuit. By having it there it prevents you from connecting an external battery while the internal battery is in circuit (and possibly causing damage).
 
3pcedev I see you're using an external AA battery connector. I removed a drum battery from an old AMD 386DX board and found the four pins that I can use for an external connector. The drum battery was 3.6v 60mAh and I was thinking about using 3 AA batteries in the holder. Do you think that's too much voltage for my 386D board? Do I need a diode like what you have? If so I may need some coaching on how.

The way I was thinking of using 3 AAs in a 4 AA holder was simply soldering a wire on both ends in one of the AA compartments - thoughts??

Thanks!
 
You can use all 4 AA batteries. The circuit is tolerant of 6V in the external battery connector. And you don't need a diode as no charging takes place in the external battery circuit. It just drains current until it's gone.
 
As Stone said go for 4x AA's while using the external battery connector. Velcro the holder somewhere in the case that isn't near the motherboard (just in case the batteries start leaking in ~10 years time).
 
I use 3xAA on the external battery connector. There is no need for a diode if you use it.
I don't know about voltage tolerance but the original battery was 4.5V so I stuck with that
and so far no problems after over 1 year.
 
I have 6v (2 x CR2032 button cells) installed on my ext. Battery connector for my AMD 386-40 board. (originally had a soldered in 3.6v Ni-Cad) That way as the batteries lose voltage over time, they will continue to be above the good threshold. Keeping perfect time now too since I installed the NIST atomic clock software in Windows 3.11. :D
 
Thanks 3pcedev and Stone for your responses!

Yep if any leaking is to occur I NEVER want it to happen on my motherboard again. I'm going to test the motherboard (386DX-4) as soon as I get the battery holder, power supply, and ISA VGA card. I may build it back up just for nostalgic fun. However, my wife is starting to wonder about me!!!! I have about six months to go before retiring and I seem to be regressing to what I thought was a more simpler computer era - right?!? My PNP days are gone! ;-)
 
Billyray,

do you by chance have the link for the "NIST atomic clock software in Windows" for Windows 3.11? Or can I simply google for the string and find it.

Thanks
 
Hope that worked for you stangman! What I especially like about the NIST software is that it keeps a log of every time Windows starts and adjusts the time. I can see exactly how much adjustment is needed after how ever much time in between boot ups. Now I know my clock is slowing down by about a minute after approx. 1-2 wks. :rolleyes: The problem with googling, is that NIST DOES have Windows 95 and later software on its own site. But the Windows 3.11 version is only on that one site, that I have been able to find. :cool:
 
stangman517 said:
Billyray,

do you by chance have the link for the "NIST atomic clock software in Windows" for Windows 3.11? Or can I simply google for the string and find it.

Thanks
Click to expand...
I'm completely sold on atomic clocks and watches. I've been wearing a Casio atomic watch for about 5 years and have had an atomic clock/thermometer combo on my bookshelf for over 10 years. It's great -- you never need to set your watch because it calls home to the atomic clock kahuna in Boulder, Co. every night via radio and gets an update. The time is always correct to the second with one of these babys and you don't need to manufacture an expensive, super-accurate timepiece in order to obtain this degree of precision because it gets calibrated automatically once every 24 hours. C'mon, even a $10 watch has the right time the day after you set it. :)
 
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