Two disk drives on one power supply.

[hueyjones70]

Does anyone know enough about electricity to determine if 2 disk drives could be operated off of one power supply.

[Van]

Sure, but you would have to have a PSU that can supply the total amperage for both. It' far more do-able now a days with switching PSU designs that can supply 4-5 Amps and are smaller and lighter then the original PSU bricks. Back in the day you would have to use a very large transformer and Caps.

Yogi

[+MacRorie]

Sure, but you would have to have a PSU that can supply the total amperage for both. It' far more do-able now a days with switching PSU designs that can supply 4-5 Amps and are smaller and lighter then the original PSU bricks. Back in the day you would have to use a very large transformer and Caps.

Yogi

 

 

I was asking about this a few years ago and was told that it would be a bad idea because it could set up some bad juju. I do not, for the life of me, remember what the bad juju was, but I remember specifically: more than one item on the same PSU: cats and dogs living together bad.

[Van]

After a little searching found this about improving the 1050's efficiency

http://www.mathyvannisselroy.nl/Atari%201050%20goes%20green.htm

This would allow a wider input voltage to the on-board regulators without the added heat of the linear regulators.

[Rybags]

With the stock PS, very much doubt it. There's probably only about 30-40% headroom of available extra current over 1 drive.

 

IMO rather than searching for a 4-5 Amp AC PS, why not just modify the drives to run directly off the +12 and +5 V from a compact PSU from a slim desktop PC.

In fact you'd probably be able to power the computer and other peripherals off the single unit as well.

[Van]

 

 

I was asking about this a few years ago and was told that it would be a bad idea because it could set up some bad juju. I do not, for the life of me, remember what the bad juju was, but I remember specifically: more than one item on the same PSU: cats and dogs living together bad.

Well, each 1050 has it's own 12v and 5V regulators so I'm at a loss to say why a single AC/AC converter couldn't feed both, as long as it can supply the total max current for both loads. I mean the Power Company does this 24x7. Not alot of difference then Two 9VAC 3A bricks plugged into the same power strip.

 

About the only thing I would add is a common GND between both drives, but I suppose the SIO cable does this fine.

Yogi

[Van]

With the stock PS, very much doubt it. There's probably only about 30-40% headroom of available extra current over 1 drive.

 

IMO rather than searching for a 4-5 Amp AC PS, why not just modify the drives to run directly off the +12 and +5 V from a compact PSU from a slim desktop PC.

In fact you'd probably be able to power the computer and other peripherals off the single unit as well.

The input circuit to the regulators is just a bridge rectifier so with a old laptop 18VDC 70W PSU or simular and the switching regulator mod I pointed to, could power both drives. The bridge could be by-passed or left in place, it will pass DC just fine. The Switching regulators have a wide input range, up to 45V, without the heat that a linear regulator would produce. So powering the +5V regulator from +18V is no problem unlike a 7805 that would melt down.

Yogi

[Level42]

Well, each 1050 has it's own 12v and 5V regulators so I'm at a loss to say why a single AC/AC converter couldn't feed both, as long as it can supply the total max current for both loads. I mean the Power Company does this 24x7. Not alot of difference then Two 9VAC 3A bricks plugged into the same power strip.

 

About the only thing I would add is a common GND between both drives, but I suppose the SIO cable does this fine.

Yogi

 

Correct, in fact, there is an Australian power supply that powers two 1050's. I have a pic but can't find it right now.

[Level42]

The input circuit to the regulators is just a bridge rectifier so with a old laptop 18VDC 70W PSU or simular and the switching regulator mod I pointed to, could power both drives. The bridge could be by-passed or left in place, it will pass DC just fine. The Switching regulators have a wide input range, up to 45V, without the heat that a linear regulator would produce. So powering the +5V regulator from +18V is no problem unlike a 7805 that would melt down.

Yogi

I looked into putting DC directly into a 1050 but there is a voltage doubler somewhere so you really don't want to try that.....unless you like smoking your 1050....

Edited August 31, 2017 by Level42

[Level42]

Ah, found it in my European Power Supplies thread:

 

http://atariage.com/forums/topic/221488-euro-power-supplies/?p=2918631

 

Looks like after market.

Edited August 31, 2017 by Level42

[1050]

But that's just two AC transformers inside one box.

 

The reason you don't want to make one stock AC

supply power both drives is because powering both

drives at the same time might overload the single

supply. You can probably get away with it too.

Just have TWO extras for when the ONE does burn

up you aren't down for the week(s) it will take

to ship in the replacements.

 

Of course if you are so cheap as to be doubling

devices onto power supplies already you won't

have extras lying about anyway.

 

Which begs the question - Why do this in the first

place?

 

Post #4 problem is that those regulators are not so

widely available in the past, but these are today:

http://atariage.com/forums/topic/268721-ac-output/?do=findComment&comment=3824750

[+tf_hh]

Does anyone know enough about electricity to determine if 2 disk drives could be operated off of one power supply.

 

Hmm, maybe I´m wrong know, but when I´m remember right, you should NOT do this, except the drives are not connected with each other (SIO buss!).

 

If different devices fed with AC from the same source are connected AFTER rectifying with each other (ground line of SIO buss for example), some parasitic current may flow and CAN (not must) damage anything - the main switch at the 1050 only switches one of the two AC inputs. So if one drive is off and the other is switched on, you will see the power LED on even if the power switch is off. Of course the drive won´t work, but... this is not a good thing.

 

Connecting more than one device together at a DC source is no problem, as long the maximum output of the power supply will not be exceeded.

[Stormtrooper of Death]

This might a bit off topic,l but in the 80s, I made a connection between Atari 600XL and MSX computer (using a modified joystick cable) for data exchange. When I powered off the Atari, while it was still connected with the MSX, the Atari could still run a program.

so, both 600XL and MSX where then running from the MSX power supply/adapter. I understand that the inner workings of the 1050 drives are difrent to the 2 computers. But I tought , it was worth mentioning in this topic.

Edited August 31, 2017 by Stormtrooper of Death

[+tf_hh]

This might a bit off topic,l but in the 80s, I made a connection between Atari 600XL and MSX computer (using a modified joystick cable) for data exchange. When I powered off the Atari, while it was still connected with the MSX, the Atari could still run a program.

so, both 600XL and MSX where then running from the MSX power supply/adapter. I understand that the inner workings of the 1050 drives are difrent to the 2 computers. But I tought , it was worth mentioning in this topic.

 

In this example both systems run at DC - then there´s no problem to connect more than one device to the power source, as I mentioned above.

[Mclaneinc]

Can't see any problems as long as the PSU supplies both the correct DC voltage and needed current (for the multiple devices) with an over head..

Edited August 31, 2017 by Mclaneinc

[Gunstar]

 

Hmm, maybe I´m wrong know, but when I´m remember right, you should NOT do this, except the drives are not connected with each other (SIO buss!).

 

If different devices fed with AC from the same source are connected AFTER rectifying with each other (ground line of SIO buss for example), some parasitic current may flow and CAN (not must) damage anything - the main switch at the 1050 only switches one of the two AC inputs. So if one drive is off and the other is switched on, you will see the power LED on even if the power switch is off. Of course the drive won´t work, but... this is not a good thing.

 

Connecting more than one device together at a DC source is no problem, as long the maximum output of the power supply will not be exceeded.

This is absolutely true, from my experience. I inherited a standard 400/800/1050 type power supply, the larger Amp model, that had an extra plug spliced to the plug wires in an attempt to power 2 drives or peripherals. I tried using it as intended with two 1050's and it caused all kinds of interference with the SIO and also some power would still blead over to the second 1050 or vice versa if only one 1050 was on (power LED would light up dimly). I would not recommend attempting it. I ended up going over all my SIO ports and cables with a fine-tooth comb in an attempt to figure out the issue, until I did try just one drive on at a time and saw the other drive's power LED on too (I usually power all drives up at once, so I never noticed until I was attempting to isolate the SIO issues). Once I unplugged one of the drives from the PSU and gave it it's own, all my problems disappeared.

 

This trick of doubling up PSU duty does, however, work with the Jaguar and Jaguar CD as long as the PSU has enough amperage for both.

Edited August 31, 2017 by Gunstar

[hueyjones70]

The idea had nothing to do with being cheap, I was thinking about eliminating clutter. I have a 1200,2 drives, a monitor, and a printer in a cabinet with pull out shelves. In a perfect world, one power supply with multiple outlets would run the computer and the drives. The next best thing would be for the wires to be like the old telephone cords.

[Osgeld]

If there are bridge rectifiers in the drives and you have both connected to a power supply and only one on and one connected to the same machine you could introduce a false reference and cause screwy things to happen, but with a DC I cant see anything damming happening... if both drives are plugged in and share a common ground point past the rectrumfryer IE the SIO port then it should all be referenced the same

 

if your using an AC supply and dont have the DC side at the same reference point (IE DC grounds hooked together) then yea some bad mojo could happen

Edited September 1, 2017 by Osgeld

[hueyjones70]

Thanks for all of the feedback, I think I will just build a larger cabinet so space will no longer be a problem.

[MrMartian]

Generally, since all Atari devices that run on 9v AC rectify that and then generate their own DC, you can power them all from one 9v AC transformer, as long as it can supply enough current. There shouldn't be any problems with ground loops, etc, as all the DC 0v lines are tied together anyways.

 

I run my 800, and a whichever disc drive I have plugged in that week, off a single transformer. Works great!