Modern power supply

If you want to ask questions about how the machine works, peculiar details, the differences between models, here it is !
How to program the oric hardware (VIA, FDC, ...) is also welcome.
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Dbug
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Modern power supply

Post by Dbug »

I few years ago I tried to replace my bulky and noisy (loud humming) Microdisc PSU by some adapter bricks with molex connectors supposedly able to deliver 2.5 amps on the 12V and 5V pins, they did "work" but after half an hour the disk drives was starting to not work very well, so I guess either they were not rated to what they actually did, or the floppy disk drives (with the controller) require more than 2.5 amps.
image_2022-05-20_081158601.png
So, now that I'm trying to use my drives again, and I'm still scared of these old PSU and I was wondering what would be a proper modern solution, which ideally would be compact, silent (no fan), and able to deliver +12 and +5 for at least two disk drives but also some +9v for the Oric?
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iss
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Re: Modern power supply

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Dbug wrote: Fri May 20, 2022 7:15 am.... they did "work" ....
Indeed! They really "work" in big quotes! :P I had 4-5 of them and none was good - unstable floating output voltages with big ripples, etc. Also, the cable hardened quickly and became brittle. In short: cheap low quality made, not recommended, can be life dangerous too!
Dbug wrote: Fri May 20, 2022 7:15 am... what would be a proper modern solution, which ideally would be compact, silent (no fan), and able to deliver +12 and +5 for at least two disk drives but also some +9v for the Oric?
To find on market ready all-in-one (5V, 12V, 9V) PSU suitable for Oric is impossible because of the "unique Oric's feature" 7905 - it needs the 9V to be totally separated (i.e. galvanic isolated) from 5V and 12V. Creating a decent switching PSU is not DIY task, not counting all obligatory safety certifications which are real nightmare! Maybe the easiest solution is to go almost the "old-fashion" way: to use big heavy transformer with 2 or 3 separate secondary windings, diode-bridge (Gretz) rectifier (discrete diodes or integrated), big capacitors and new high-efficient DC-DC Stabilizers (Buck Converters). This will definitely work but only the transformer is like ~25EUR and >0,5 kg. (if this matter... :)).

Here is what I found and the results are good:
P_20190217_233314.jpg
I replaced original connector with DIN-5 and use it with Telestrat+floppy (the Telestrat's ugly connector is replaced too - the top PCB):
P_20190217_232608.jpg
The quality of this PSU - "APD DA-30C01" is far better. Mine is rated for 2A for both 5V and 12V but exactly the same model can be found as 1.5A. Some sample links: HERE and HERE. (If someone is interested in this Telestrat "upgrade" I can post more pics).

I will check it how it works with 2 floppy drives + Microdisc during my work on the copy program.
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Re: Modern power supply

Post by Dbug »

I guess these are the same (seem to be the 1.5 A version)

https://www.digitalimpuls.no/western-di ... l-elements

So I guess I could get one of these for each drive I want to use together, and replace the connectors by some DIN 4 FEMALE connectors so it's directly compatible with the Microdiscs units.

Regarding the copy program, I was wondering if technically it would be possible (and reliable) to do something like having one source and one, two or three targets, to basically duplicate multiple disks at the same time, the global writing time would be the same, but that would reduce the number of disk swaps :)
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Re: Modern power supply

Post by iss »

Dbug wrote: Sat May 21, 2022 8:51 amI guess these are the same (seem to be the 1.5 A version).
So I guess I could get one of these for each drive I want to use together, and replace the connectors by some DIN 4 FEMALE connectors so it's directly compatible with the Microdiscs units.
Yes, the specs are the same - it will work. The current price 90,- NOK (8.68 EUR) is really good bargain. :)
EDIT: This what to expect when you cut the mini-DIN connector and indeed, the one I used is 1.5A too :
20180621_140421.jpg
Dbug wrote: Sat May 21, 2022 8:51 am
Regarding the copy program, I was wondering if technically it would be possible (and reliable) to do something like having one source and one, two or three targets, to basically duplicate multiple disks at the same time, the global writing time would be the same, but that would reduce the number of disk swaps :)
Interesting! IMHO it's doable with simple jumpering all targets as drive B- :roll: But I'm not sure and need to test, at-least I don't see any "prerequisite for smoke and fire"...
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Re: Modern power supply

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Oh the idea was not send the write command to three drives at the same time. :lol:

Just that that allows to read the data from the source disk only once, then write it to each of the three drives, verify what was written, then next track.
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Re: Modern power supply

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The real duplicators work in parallel without verify - they rely on the good quality of media. In our case the verify is more important than writing :lol:
And yes, I see the workflow in exactly same way you described read one track then write it to targets and compare written data with original (2 track buffers will be used of course).
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Re: Modern power supply

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Would probably even make sense to try to read the source track more than once, just to make sure that the source disk is not unreliable.

On the Atari ST and Amiga protection, they used things like "flacky bits" which were tracks "formatted" in a way that some bits would change randomly when reading it, the protection would read them twice, and if it got the same content twice then that was most probably as copied disk.
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Re: Modern power supply

Post by Dbug »

Received and modified one of the power bricks, working nicely :)



I also ordered some switches, I'll put them on the mains cable so I can switch on/off without having to unplug all the time, and since these power bricks have a small green light indicator, it will be easy to see if they are on or not.
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