Help with RTC


Enlighted (5172)

NYYRIKKI's picture

08-04-2018, 15:50


I'm just changing my SVI-738 PSU to an PicoPSU. I just started to think that now that I have standby power output I might also put in RTC chip. (I don't want batteries inside)

I found schematics by Henrik Gilvad, but they look a bit over complicated for my purposes...

Now my question is, can I just connect it like this?

Any thoughts?

If I get this part done I'll then continue planning to next phase where I plan to use the /ALARM output for powering up the PSU and maybe using unused bits of floppy motor/side select etc. register to power down the machine by software when needed.

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By lkpalwa

Resident (53)

lkpalwa's picture

08-04-2018, 22:57

I think it should work, but i will add a 1N4148 to the schematics on pin 18

Nyyrikki thx for your help last time, I have also added the components to SVI 738 on the PCB as the original schematics, I will use a Lithium CR2032 battery instead, with a 220 OHM + 1N4148 connected to the + on the battery.
(as the AMIGA Varta killer schematics) I also thinking of using a PicoPSU so please add you expirence here Smile
and replace the battery Smile if you make it work


Enlighted (5172)

NYYRIKKI's picture

17-04-2018, 01:09

So sorry for late reply... My real life™ has been quite hectic lately... ATM I'm waiting for correct power connector (C8), power button (momentary rocker switch) and NAND-chips from China. That may take some time, but I'll update you once I have all back together. The NAND-chips are used to form RS-FlipFlop in order to drive the PSU control from external sources as well... Naturally just a regular switch would be fine as well although a bit boring Smile... ATM I actually have a normal rocker switch + old AT power supply and it is working fine. For some reason the original SVI-PSU was giving me -24V on -12V output... I hope it has not damaged the RS-chip, but I've not tested it for a long time.

After your comment I was brave enough to order the RP5C01 as well... Let's see if I get it to work like this... Currently I just hope I'll find rest of the stuff somewhere from my drawers... I think I'll need to dig in there some day soon or just go back ordering some more stuff.

This absolutely makes no sense, but MSX is a nice hobby. Smile

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