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Simon Carter

Alternative 1050 PSUs

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Would you get away with using a universal power supply? I just got my second 1050 unit, sans SIO or PSU. I have a universal supply that happily powered my 410p tape drive, but wondered whether this would be suitable for the 1050?

 

As always, thanks in advance

 

Si

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what is this universal power supply, does it provide AC as it's output? (like a variac)

most I've seen are DC only on the output, and if that is the case then no.

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On 8/12/2021 at 9:43 PM, _The Doctor__ said:

what is this universal power supply, does it provide AC as it's output? (like a variac)

most I've seen are DC only on the output, and if that is the case then no.

image.thumb.png.4a6edd079e979d2ad08ce5650a0c55f2.png

 

This badger... I'm guessing that as this pops out DC that it'd fry my 1050 quite quickly

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7 minutes ago, Simon Carter said:

This badger... I'm guessing that as this pops out DC that it'd fry my 1050 quite quickly

 

It's a pretty safe bet if it says "Universal Power Supply" it's output is DC. Apart from a Variac which would probably be

physically big, you would need a multi-tap step down transformer internally to provide different output voltages and

a switch to select which output you want, again probably larger and certainly heavier.

 

Also if the input voltage is 110VAC to 240VAC it's definitely a switch mode PSU and a DC output.

 

AC PSU's can't do that, the relationship between input and output is a fixed ratio so a 240VAC rated PSU @9VAC output

will only give 4.125 VAC when connected to 110VAC.

Connecting a 110VAC @9VAC output connected to 240VAC would give you lots of smoke and maybe a big bang :)

 

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55 minutes ago, Simon Carter said:

but I'm UK based

No worries, I ship worldwide so your location does not change anything to me.  But I understand the cost of shipping.

 

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From what I've learned and own experience: usually you can feed DC into a device that expects AC. Most of those devices have a rectifying bridge and a voltage regulator inside to generate e.g. 5V DC from the 9V AC. In a few special cases the AC might be used for outputs or custom chips.

 

If you feed DC into it, that means half of the rectifying bridge won't operate, but the regulator still does. Temperature measurements on e.g. NES units have proven that nothing gets hotter than when you feed AC into it, and that long term usage doesn't seem to harm it.

 

However: NEVER DO THE OPPOSITE, FEED AC INTO A DEVICE THAT EXPECTS DC. That will for sure break the device. At best the voltage regulator craps out, at worst hard to find chips break.

 

Another thing to note is that the 1050 uses a fair amount of power, which means that even if you got a 9VAC transformer that works with an Atari 410, it might be too weak for the floppy drive. It has been discussed before, but I think you want at least 2A (18 VA), ideally 3A (27 VA) to have the 1050 operate properly. I've used a random 9VAC @ 2A power supply found at a flea market with my 1050 but wouldn't try one of those 9VAC @ 1A supplies I've also found.

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No, when you feed it DC only half of the diodes are used... almost double the current can go through the remaining two diodes and they cook... just because some device or another doesn't cook because it's not using the components to capacity doesn't mean it won't happen with another device!!

Dead 1050 diodes is a common failure from folks feeding them DC... DON'T DO IT.

 

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Fair enough. I suppose that is due to the power requirements, that a system powered by 9VAC @ 1A to a bigger extent would withstand DC voltage than a system powered by 9VAC @ 2A where it would pull more effect through the remaining diodes then. I never considered that each diode has a maximum of current flowing through it.

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You are forgetting that 1050 definitlly needs AC for its internal voltage multliplier to work. Internally 1050 produces two voltages. 5 and 12 volts.

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10 hours ago, carlsson said:

From what I've learned and own experience: usually you can feed DC into a device that expects AC. Most of those devices have a rectifying bridge and a voltage regulator inside to generate e.g. 5V DC from the 9V AC. In a few special cases the AC might be used for outputs or custom chips.

The only problem with using a DC supply is that the now redundant rectifier diodes will drop approx. 0.6V, so

if starting with 5.0V, the voltage through the voltage regulator is 4.4VDC, so if your device is sensitive to the supply

voltage, it may cause problems.

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This is what I genuinely love about this site - you pick up so much useful info, I'm just beginning to teach myself the joys of electronics so at some point in the future, all these replies will make sense to me. 

 

All the best 

 

Si

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I currently make 9V AC power supplies, using a linear 9vac 3A transformer, a 0.25A fuse (using 220V as input) and a Toshiba notebook plug cable. They fit very nicely on the 1050 and xf551.

 

i strongly suggest to put a fuse on it, in order to prevent any damage on the drive.

 

 

0B850690-283E-4336-8E77-D6167E7C1CCE.jpeg

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Thanks! I bought the parts locally on electronic shops, whose products are mostly from China. Then I adapt the parts and assemble them into the plastic box.

Finally, I print a label using adhesive paper with a protection film over it. That brings a glossy finish.

Edited by Wilheim
Orthography, as usual.

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