Atom PSU. Better set to 8v or 5v?

discussion of games, software, hardware & emulators relating to the Acorn Atom and Acorn System machines.
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ukretrogamer
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Atom PSU. Better set to 8v or 5v?

Post by ukretrogamer » Mon Aug 30, 2010 11:55 pm

Having just picked up a pristine boxed Atom, I'm now in need of a suitable PSU to use with it.

I've looked over the included technical documentation and checked inside the Atom. The appropriate links (LK6 & LK7) have been left open so I know I'll need an 8v PSU as it currently stands.

As I intend to upgrade the Atom to as high a specification as I can, am I better closing the links to bypass the regulators & capacitors and going straight for a 5v regulated PSU?

If so, can anyone recommend an "off-the-shelf" PSU which is up to the job.

I'd prefer the PSU to be as plug and play as possible. If the voltage can be changed with a switch, it could be improperly-set, risking damage to the Atom.

A single "Atom sized" connector is also preferred to one of those multi-prong, one-size-fits-all PSUs which can be bought from the likes of Maplin, etc.

Thanks in advance
Mark
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Re: Atom PSU. Better set to 8v or 5v?

Post by station240 » Tue Aug 31, 2010 2:12 am

An 5V PSU would mean less heat inside the case, plus they are easier to get. You may be able to get a 5V regulated supply from something else, try a dead digital set top box.

Or just buy a supply with the interchangeable plugs, cut the end off and solder a proper plug on.

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Re: Atom PSU. Better set to 8v or 5v?

Post by sirmorris » Tue Aug 31, 2010 6:18 am

The Atom power socket is a non-standard sizing. You won't find a plug for it anywhere - I've been looking for 5 years. If you do though - let me know ;)

All my Atoms get a flying lead with standard sized socket ready for regulated 5Vs. As already said less heat is good. I'd replace the socket on the board ideally but I'd need to find one with the right footprint. Splicing the lead from the original supply isn't normally an option as they're rare beasts.

I have an old Nokia charger which kicks out 5V at 2A. Not sure what kind of phone required _that_ amount of juice...

Congrats on getting the nice Atom. You'll be needing some mass storage then, I'm guessing 8)

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Re: Atom PSU. Better set to 8v or 5v?

Post by John Kortink » Tue Aug 31, 2010 7:45 am

ukretrogamer wrote:As I intend to upgrade the Atom to as high a specification as I can, am I better closing the links to bypass the regulators & capacitors and going straight for a 5v regulated PSU?
Yes. Better dissipate heat outside if you can.
ukretrogamer wrote:If so, can anyone recommend an "off-the-shelf" PSU which is up to the job.
There are plenty of regulated 5V-only supplies on the market. I use Ebay item #230486294852.
ukretrogamer wrote:A single "Atom sized" connector is also preferred to one of those multi-prong, one-size-fits-all PSUs which can be bought from the likes of Maplin, etc.
Just cut off the plug and install a 2.1/5.0 mm one.

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Re: Atom PSU. Better set to 8v or 5v?

Post by John Kortink » Tue Aug 31, 2010 7:46 am

sirmorris wrote:The Atom power socket is a non-standard sizing. You won't find a plug for it anywhere - I've been looking for 5 years. If you do though - let me know ;)
Unless you have a different DC socket on your Atom than I do, it's simply a standard 2.1 mm inside/5.0 mm outside DC plug. Readily available.

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Re: Atom PSU. Better set to 8v or 5v?

Post by ukretrogamer » Tue Aug 31, 2010 8:35 am

sirmorris wrote:Congrats on getting the nice Atom. You'll be needing some mass storage then, I'm guessing
I certainly will once I confirm it's working as it should.

There seem to be more empty sockets on the motherboard than occupied ones.

Is this normal?

Apart from your own MMC (Which I *DO* intend buying once I know mine works) what other (Acorn intended) upgrades can still be made?

Also, what's the polarity of the power connector? Centre-Positive?

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Re: Atom PSU. Better set to 8v or 5v?

Post by Prime » Tue Aug 31, 2010 10:30 am

John Kortink wrote:
sirmorris wrote:The Atom power socket is a non-standard sizing. You won't find a plug for it anywhere - I've been looking for 5 years. If you do though - let me know ;)
Unless you have a different DC socket on your Atom than I do, it's simply a standard 2.1 mm inside/5.0 mm outside DC plug. Readily available.
Seconded, I'm using a standard 5V 2.5A PSU from Rapid, which has a standard plug on it works fine with (what I assume to be) the original socket in one of my Atoms.

The PSU I am using is one soemwhat like this :

http://www.rapidonline.com/sku/Electric ... 95/85-3940

I say somewhat like, as I bought it from rapid, and it has the same specs as this one, but a slightly different case, so this is prolly the newer version.

Cheers.

Phill.

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Re: Atom PSU. Better set to 8v or 5v?

Post by Prime » Tue Aug 31, 2010 10:33 am

ukretrogamer wrote:
sirmorris wrote:Congrats on getting the nice Atom. You'll be needing some mass storage then, I'm guessing
I certainly will once I confirm it's working as it should.

There seem to be more empty sockets on the motherboard than occupied ones.

Is this normal?
Define "empty sockets", better still take a piccie and post it that way we'll be able to tell what goes in the empty ones.....
Apart from your own MMC (Which I *DO* intend buying once I know mine works) what other (Acorn intended) upgrades can still be made?

Also, what's the polarity of the power connector? Centre-Positive?
I believe so, however it would be best to check using a multimeter.

Cheers.

Phill.

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Re: Atom PSU. Better set to 8v or 5v?

Post by ukretrogamer » Tue Aug 31, 2010 12:59 pm

Prime wrote:
Apart from your own MMC (Which I *DO* intend buying once I know mine works) what other (Acorn intended) upgrades can still be made?

Also, what's the polarity of the power connector? Centre-Positive?
I believe so, however it would be best to check using a multimeter.
What I meant was before plugging the PSU in, should I be checking for positive or negative centre polarity. I can check the PSU but which is the correct polarity for the Atom?

Regards
Mark

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Re: Atom PSU. Better set to 8v or 5v?

Post by Prime » Tue Aug 31, 2010 1:06 pm

ukretrogamer wrote:
Prime wrote:
Also, what's the polarity of the power connector? Centre-Positive?
I believe so, however it would be best to check using a multimeter.
What I meant was before plugging the PSU in, should I be checking for positive or negative centre polarity. I can check the PSU but which is the correct polarity for the Atom?
Well what I meant was to take the meter, set it on continuity, place it on the VCC terminal of one of the ICs, and then test the two pins on the power connector note which one gives a beep. Do the same for the ground pin.

You can of course find out which is the VCC and ground pins from the chip data sheets, but typically for most of the chips in the Atom, cirtainly the ROMs, any 74LSxx series chips it's typically bottom left is ground, top right is VCC.

Repeat for a couple of different types of chip just to be sure, and that should tell you the polarity to use.

Cheers.

Phill.

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Re: Atom PSU. Better set to 8v or 5v?

Post by station240 » Tue Aug 31, 2010 1:09 pm

ukretrogamer wrote:
Prime wrote:
Apart from your own MMC (Which I *DO* intend buying once I know mine works) what other (Acorn intended) upgrades can still be made?

Also, what's the polarity of the power connector? Centre-Positive?
I believe so, however it would be best to check using a multimeter.
What I meant was before plugging the PSU in, should I be checking for positive or negative centre polarity. I can check the PSU but which is the correct polarity for the Atom?

Regards
Mark
Easy way to check, attach one multimeter probe to something obviously earthed, like the outside of the modulator output. The the other probe to the plug you want to check.

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Re: Atom PSU. Better set to 8v or 5v?

Post by ukretrogamer » Tue Aug 31, 2010 2:44 pm

Does the polarity change from one machine to another?

I'll use my multimeter and check before I plug anything in but was sort of expecting a "yes or no"/"positive or negative centre" answer. :?

Thanks for showing me how to fish rather than feeding me Salmon though! :D

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Re: Atom PSU. Better set to 8v or 5v?

Post by Prime » Tue Aug 31, 2010 2:54 pm

ukretrogamer wrote:Does the polarity change from one machine to another?

I'll use my multimeter and check before I plug anything in but was sort of expecting a "yes or no"/"positive or negative centre" answer. :?

Thanks for showing me how to fish rather than feeding me Salmon though! :D
Well I'm kind of at work and my Atom is at home.....like I said I think it's centre +ve, but I'm not sure and as I didn't have the machine here to check I wanted to make sure you didn't kill your valuable Atom :) :)

Cheers.

Phill.

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Re: Atom PSU. Better set to 8v or 5v?

Post by ukretrogamer » Tue Aug 31, 2010 3:02 pm

Thanks Phill.

I've not picked up a psu myself yet and I'm also at work.

I wasn't being sarcastic, I learned something.

As I said, it's easy enough to find out if a psu is centre + or -, but I've never had to check a device to see if *it* needs a + or - supply. Your answers told me how to find this for myself on future projects.

No sarcasm intended...

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Re: Atom PSU. Better set to 8v or 5v?

Post by BeebMaster » Thu Sep 02, 2010 5:52 pm

I've never really known what is the right power requirement for an Atom, some of the ones I've seen have the voltage regulators on board, some of them have the links set, and all of them have different sized power jacks! I've certainly seen them with the hole widened with a soldering iron.

With my Atoms I use the same power supply as I use for my digital camera which is a 2A with variable DC voltage setting from 3V to 7V and removable ends.

I know I'll be told that this is the surest way to instantly destroy a priceless Atom and I'm sure I wouldn't recommend it to anyone, but what I've always done is start off at 3V and increase it till some sensible output appears on the screen and leave it at that.
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Re: Atom PSU. Better set to 8v or 5v? [Success]

Post by ukretrogamer » Sat Sep 04, 2010 4:09 pm

I can now confirm my Atom working.

Soldering links and fitting jumpers over the bypass links and using a 5v/2A external PSU, I can get the Atom to fire up and write basic BASIC.

In my case, the PSU required was centre-positive.

Now on to my next question. How far can it be upgraded?

I'll be harassing Charlie for an AtomMMC next but how do I know what is fitted and what *can* be?

Thanks to everyone who helped in getting this going without risking it blowing up in my face.

Wow. No CLS command. How pre-historic. I thought the Apple II was bad with its "HOME" command. pre-historic or just pre-standards?

I'll take some photos of the board so I can get an idea of what I do and don't have. From the number of free sockets, I suspect I have less than most.

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Re: Atom PSU. Better set to 8v or 5v? [Success]

Post by Prime » Sat Sep 04, 2010 4:37 pm

ukretrogamer wrote:I can now confirm my Atom working.

Soldering links and fitting jumpers over the bypass links and using a 5v/2A external PSU, I can get the Atom to fire up and write basic BASIC.

In my case, the PSU required was centre-positive.

Now on to my next question. How far can it be upgraded?
Depends how obsessive / determined you want to be :)

I have a 32K Atom, Charlie's AtomMMC fitted, I now have a disk for it, and am working on designing a modern colour board. (I currently have the prototype built up on breadboard).

Not got round to fitting an Econet interface, but I have seen it done.

And then there's the AtomClone........
I'll be harassing Charlie for an AtomMMC next but how do I know what is fitted and what *can* be?

Thanks to everyone who helped in getting this going without risking it blowing up in my face.

Wow. No CLS command. How pre-historic. I thought the Apple II was bad with its "HOME" command. pre-historic or just pre-standards?
I believe the command you are looking for is clear, which IIRC also sets the video mode, asuming that you have enough video ram.
I'll take some photos of the board so I can get an idea of what I do and don't have. From the number of free sockets, I suspect I have less than most.
Yeah I believe a minimum spec Atom would only have 4x2114 RAM chips, one ROM, no 6522, and some of the 74LS chips missing.

The Atom Circuit diagram is available online : http://www.bbcdocs.com/hardware.htm (circuit diagrams are near the bottom).

That should help you see what is missing.

Cheers.

Phill.

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Re: Atom PSU. Better set to 8v or 5v?

Post by ukretrogamer » Sat Sep 04, 2010 5:20 pm

Here we go:

Lots of empty sockets. Could anybody tell me the likely configuration of my machine as it currently stands and what I can upgrade to?
(I still havent found an equivilent to "PRINT FRE(0)" on the Acorn machines!)

I've tried to overlap the photos to give an overall view of side 2. I take it there's nothing to be upgraded on side 1?

Also, could someone supply links to suppliers for the required components? If anyone has any upgrade components spare, I'd be willing to settle up via PayPal if it's convenient?

I'm not looking to upgrade to silly levels, just enough to run whatever software is out there, comfortably. (Not much software, AFAIK)

...Perhaps just enough to run everything available on the AtomMMC?

Regards
Mark
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Re: Atom PSU. Better set to 8v or 5v?

Post by sirmorris » Sat Sep 04, 2010 7:20 pm

This is a basic Atom, 1K + 1K, no VIA.

Your configuration will give you 512 bytes allocated to screen RAM and 512 bytes for program. Suffice to say you won't be playing snapper. Or printing, though that's rarely a problem for us these days..!

There's a lot to learn here so let's just say now you're in for the long haul! I'm a total enthusiast so you can count on me chipping in.

You'll be needing some 2114 dynamic RAM chips - or you can go ahead and replace them with 6264s. The 6264 option will require some light soldering / building a small board.

I've got 2114s that you can have. I dare say Phill will have some too ;) I'm giving a cheeky wink there as our Mr. Prime has produced a lovely memory upgrade board which will fill the holes on one side of your memory map quite nicely. Pictures please, Phill!

Where are you based? Will you be making it to one of the events like replay or the next RCM meet? I won't be at the former but I'd be happy to help you beef up your machine in November.

C

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Re: Atom PSU. Better set to 8v or 5v?

Post by Prime » Sat Sep 04, 2010 7:46 pm

sirmorris wrote:This is a basic Atom, 1K + 1K, no VIA.
No floating point rom either.
Your configuration will give you 512 bytes allocated to screen RAM and 512 bytes for program. Suffice to say you won't be playing snapper. Or printing, though that's rarely a problem for us these days..!

There's a lot to learn here so let's just say now you're in for the long haul! I'm a total enthusiast so you can count on me chipping in.

You'll be needing some 2114 dynamic RAM chips - or you can go ahead and replace them with 6264s. The 6264 option will require some light soldering / building a small board.

Though the board can probably be built up on stripboard.
I've got 2114s that you can have. I dare say Phill will have some too ;) I'm giving a cheeky wink there as our Mr. Prime has produced a lovely memory upgrade board which will fill the holes on one side of your memory map quite nicely. Pictures please, Phill!
Ok Ok, but I'll do it in a seperate thread so's not to hijack this one :)

Cheers.

Phill.

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Re: Atom PSU. Better set to 8v or 5v?

Post by ukretrogamer » Sat Sep 04, 2010 8:03 pm

sirmorris wrote:This is a basic Atom, 1K + 1K, no VIA.

Your configuration will give you 512 bytes allocated to screen RAM and 512 bytes for program. Suffice to say you won't be playing snapper. Or printing, though that's rarely a problem for us these days..!

There's a lot to learn here so let's just say now you're in for the long haul! I'm a total enthusiast so you can count on me chipping in.

You'll be needing some 2114 dynamic RAM chips - or you can go ahead and replace them with 6264s. The 6264 option will require some light soldering / building a small board.

I've got 2114s that you can have. I dare say Phill will have some too ;) I'm giving a cheeky wink there as our Mr. Prime has produced a lovely memory upgrade board which will fill the holes on one side of your memory map quite nicely. Pictures please, Phill!

Where are you based? Will you be making it to one of the events like replay or the next RCM meet? I won't be at the former but I'd be happy to help you beef up your machine in November.

C
Hi Charlie

I'm hoping to pickup some tickets for R3play from Blackpool's "Who" store over the next couple of weeks. I support a site based in Bispham and I'll definately be in the area within the next week or two.

I suspected it hadn't already been upgraded!

If you'd help me upgrade it then, I'd really appreciate it.

What sort of specification could you take it to?

Ideally, I'd like to get composite output working, possibly floating-point and obviously more RAM. What's a VIA?

Is it possible to upgrade to a reasonable spec without too much modification? As the machine is pretty much factory-fresh, Ideally, I'd like to keep the upgrades as authentic as possible. (AtomMMC excepted!)

Regards
Mark

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Re: Atom PSU. Better set to 8v or 5v?

Post by Prime » Sat Sep 04, 2010 8:40 pm

ukretrogamer wrote: Ideally, I'd like to get composite output working,
That's easy pins 9 and 10 of PL4 are mono composite video, 9=video, 10=gnd.

It's easy enough to either fit a 2x5 connector and just connect 9&10 to a lead or to solder the lead to the board on the back side of pins 9 & 10.

Cheers.

Phill.

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Re: Atom PSU. Better set to 8v or 5v?

Post by ukretrogamer » Sat Sep 04, 2010 8:51 pm

Prime wrote:That's easy pins 9 and 10 of PL4 are mono composite video, 9=video, 10=gnd.

It's easy enough to either fit a 2x5 connector and just connect 9&10 to a lead or to solder the lead to the board on the back side of pins 9 & 10.
I saw that somewhere. Probably in the paperwork/manuals/schmatics which came with the Atom.

Where do I start looking for a 2x5 connector? Is it something Maplin might sell? Could I cut another connector down?

Ideally, I'd like to do this without too much modificaion of the Atom. At least irreverisible modification!

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Re: Atom PSU. Better set to 8v or 5v?

Post by sirmorris » Sat Sep 04, 2010 9:46 pm

An unmodified Atom? :?

Heh, I've never seen one ;)

The video connector _could_ be made from a hacked IDE cable. Or I could mail you one. I've got your PM and I'll make up a shopping list and get back to you 8)

I'm not going to replay (too far/used up too many geekend credits at Bletchley) but Phill will be - ITR?

C

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Re: Atom PSU. Better set to 8v or 5v?

Post by iomanoid » Sat Sep 04, 2010 9:51 pm

Noooooooooooo Charlie you have to come to R3play... I will feed you and wash you...
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Re: Atom PSU. Better set to 8v or 5v?

Post by ukretrogamer » Sat Sep 04, 2010 10:07 pm

sirmorris wrote:An unmodified Atom? :?

Heh, I've never seen one ;)
I'd never seen an Atom in real life *at all* until last weekend. It was collected locally and was being sold as "Suspected not working".

When I collected it, the seller said he'd bought it second hand about 20 years ago, couldn't get it to power up and put it away in its box. I suspected there was nothing wrong with it as he told me it needed a 5v PSU which he'd tried unsuccessfully. I'd already done some research and read that an unmodified Atom needed 8v. It was a gamble but it paid off.
sirmorris wrote:The video connector _could_ be made from a hacked IDE cable. Or I could mail you one. I've got your PM and I'll make up a shopping list and get back to you 8)
Cool. That's exactly the help I need with it. PayPal and my immeasurable gratitude await!

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Re: Atom PSU. Better set to 8v or 5v?

Post by sirmorris » Sun Sep 05, 2010 7:59 pm

iomanoid wrote:Noooooooooooo Charlie you have to come to R3play... I will feed you and wash you...
Cancel the wedding Carruthers! I'm off to Blackpool!
8)

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Re: Atom PSU. Better set to 8v or 5v?

Post by Arcadian » Sat Sep 18, 2010 8:58 pm

sirmorris wrote:I'm off to Blackpool! 8)
Woah - seriously? :D
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Re: Atom PSU. Better set to 8v or 5v?

Post by iomanoid » Sun Sep 19, 2010 1:33 am

Arcadian wrote:
sirmorris wrote:I'm off to Blackpool! 8)
Woah - seriously? :D
Carruthers?? :shock:
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Re: Atom PSU. Better set to 8v or 5v?

Post by sirmorris » Sun Sep 19, 2010 6:40 am

It looked possible for a minute there but it was only for a minute :(

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