USB power supply for CPC/PLUS

[Bryce]

I doubt the tracks were fried. The charge from a screen is static electricity. It has a very high voltage, but almost zero current, so there is not enough energy present to burn the track. You can try it for yourself: Charge yourself up on a carpet and then short yourself to a radiator using the thinest wire you can find. A spark will jump across the gap (indicating a very high voltage), but the wire won't burn or even get hot (indicating very low current).

Semi-conductor materials on the other hand are voltage sensitive, which is why static destroys chips.


Bryce.

[GUNHED]

Well, I won't try it by myself (again). 

[chinnyhill10]

I thought all USB supplies were 5v and regulated, maybe not.

You only need to watch Big Clive's Youtube channel to see how badly some perform. At best they are designed for charging, not powering a 35 year old micro. Sure they'll work but if you insist on using one at least use one rated to work with a Pi.

[chinnyhill10]

I need one of these (RS) for a Plus, is there an adaptor for the output connector?

Yep. Got mine on Ebay. About a quid. Just get the best deal at any given moment, will be loads.


Or if you use the PSU search on RS they may have one at the right size for a Plus. But personally I just use the same supply + the adaptor.

[Bryce]

You only need to watch Big Clive's Youtube channel to see how badly some perform. At best they are designed for charging, not powering a 35 year old micro. Sure they'll work but if you insist on using one at least use one rated to work with a Pi.

Yes, but Big Clive tears down the cheapest Chinese rubbish he can find. Inside an original Samsung / HTC / Sony USB PSU looks a lot different.

Bryce.

[chinnyhill10]

Yes, but Big Clive tears down the cheapest Chinese rubbish he can find. Inside an original Samsung / HTC / Sony USB PSU looks a lot different.

Bryce.

He's also torn down high quality supplies, indeed the Ikea 3 port units I use I purchased on his recommendation. Still wouldn't use one to power a CPC though.

[Bryce]

Maybe I've only watched his "thrashy" videos

Bryce.

[ComSoft6128]

Thanks to everyone that contributed to this thread, the info was helpful - RS PSU ordered this morning.

Cheers,

Peter

[fgbrain]

Okay... everyone said NO in short
But I like experimenting!!



https://youtu.be/XNh52-vJc6M

I have now a mobile 6128!!!

[Bryce]

Eh, no. I never said it wouldn't work.

If the USB device can supply enough amps, then any 5V supply will power a CPC. How many amps can that powerbank supply?

Bryce.

[fgbrain]

It has two outputs of 5V:.  One with 1A and the second with 2.4A.
I use the second one..
When I get a second cable I will try adding an external drive or my Gotek.

[chinnyhill10]

I have now a mobile 6128!!!

Clearly it will work. But what is the protection for the CPC inside the power bank? Rather misses the point we have been trying to make. The CPC has no internal protection, your PSU must be good quality to PROTECT the CPC.

[remax]

In a few weeks, a new topic "i fried my CPC, can someone help me ?" 

[Bryce]

2.4A is ok and any decent powerbank will have better protection and regulation than the GT65 or CTM's ever had.

Bryce.

[pelrun]

Seconding what Bryce says here. Modern switchmode power supplies are *extremely* well regulated. Unlike the old transformer power bricks which often had an open-circuit voltage significantly higher than the rating.


I actually recently found USB and other 5v power supplies are actually *too low* for reliable operation of my 6128. I've not had much luck with my M4 wifi card or other peripherals, even when externally powered. There's a good .5v or better voltage drop across the system. Replacing the supply with a 5.1v PSU I recently obtained for my Raspberry Pi's seems to have fixed it. My M4 now works perfectly even without the recommended second supply!

[dragon]

 Have here a dual usb that tell it  output 4,2a


https://www.amazon.it/Ewent-Caricatore-Portatile-Doppia-Bianco/dp/B00O2RD59A

[fgbrain]

...
Actually recently found USB and other 5v power supplies are actually *too low* for reliable operation of my 6128. I've not had much luck with my M4 wifi card or other peripherals, even when externally powered. There's a good .5v or better voltage drop across the system.....

I think I agree. If i use the splitter cable and power both CPC and Gotek Emu from the power bank, the picture gets black n white but everything else looks good...
So to my poor knowledge this means USB power is weaker.

[Bryce]

Have here a dual usb that tell it  output 4,2a


https://www.amazon.it/Ewent-Caricatore-Portatile-Doppia-Bianco/dp/B00O2RD59A

That'll be 4.2A total, so 2.1A per socket. Most USB cables would get very warm trying to pass 4.2A, which is why all these new fast charging systems such as Qualcomms quick charge use up to 12V instead of 5.

Bryce.

[protek]

This is not USB but it supplies both 5 and 12 volts.
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F222415223126

[Bryce]

This is not USB but it supplies both 5 and 12 volts.
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F222415223126

I wouldn't reccommend any bare 220V PSU to anyone who doesn't know exactly what they are doing. If members want to leave the forum that's fine, but I'd prefer they don't do so in a box.

Bryce.

[GUNHED]

So, does this mean that the PSU pesented by Protek is bad? Let's assume it's in a save box, would be be a good pick?

[Bryce]

So, does this mean that the PSU pesented by Protek is bad? Let's assume it's in a save box, would be be a good pick?

It looks relatively well designed and built. Of course the actual performance can only be confirmed by having one and measuring the output. It's impossible to say how good a PSU is just by looking at it. The only reason I would choose something else to recommend, is the fact that it is extremely dangerous in the delivered state if you don't know what you are doing.

What I can say about the design just by looking: The capacitor on the left of the transformer (EC1) would charge up to almost 400VDC and I can see no bleed resistor to discharge it on either side of the PCB. So even after disconnecting this from the mains it would have the potential to kill you. Something most beginners will not know. It also looks like the design has been "cost optimised" several times, so the performance will not be as good as the designer intended.


Bryce.

[Bryce]

Since you asked and I have a minute. Here's some visual analysis of the PCB (regarding cost optimising) which would all speak against buying this:

A, B + C: These should be the mains filter capacitors. Leaving these out won't effect the output of the device, but will cause it to create noise on the mainsline - Effect: Expect noticable interference on monitors and audio equipment that are in the same room.

D + E: They've removed one rectifying diode from each power rail, so the device is only rectifying one half of the sinewave wave now - Effect:
More ripple on the 5V and 12V output rails.

F + G : They've removed the two output inductors - Effect: Ripple and/or noise on the 5V and 12V rail. Probably too much for a CPC at this stage.


H: They've removed the output capacitor (most likely on the 12V rail) - Effect: Because D + F are already gone, the 12V rail is more or less unfiltered now, it will look a mess. I wouldn't connect it to a CPC.

I: The hot-side capacitor has been downsized. In itself, this shouldn't effect the output of the device, but it would shorten the expected lifetime of the device.

Hope that gave you some insight.


Bryce.

[GUNHED]

That is shocking! 


EDIT: Slowly I begin to think that we (as CPC community) should do something like a data collection of "save things" regarding hardware (and maybe also other topics). Something like a positive list.

[Bryce]

Possible, but it's difficult for things like this. A PSU that is available today may not be available in 6 months. And even if it is, if it's a closed device, you don't know what they changed over time.

The example above is a classic case of cost-optimising - Remove anything that doesn't stop it from working. This is done on everything these days. Design it well, sell a load of them and then optimise it down to increase profits. This is why you'll often hear: "The early edition was better" on everything from Laptops to Washing machines. It happens less on things like phones, because their lifecycle is so short.


Bryce.