Voltage Advice Needed

[eslapion]

Oh, and btw - surely because we have 220v here all I need to do is plug in 2x 110v power adapters in the same socket to balance out the power?

Actually, if you are absolutely certain your power adapters use transformers and are not switching devices, you could actually plug them both in series and there is a great deal of chance that it would work and it would be safe.

Just make sure the load attached to both of them is pretty much equal to ensure they have the same input impedance. They will both act as voltage dividers absorbing the voltage drop evenly across one another...

[idrougge]

Yes, but things using standard black wall-warts, and not custom Commodore supplies, will have voltage stabilisers inside, because it would be suicidal for the electronics to rely on a cheap wall-wart to supply exactly the required current and voltage.

WRONG!

I have a very nice internet router here and a USB video capture box. Both use a nice little switching power supply walwart.

Both walwarts are rated for 5V 2A and the symbol on it says it is regulated. Just for the fun of it, I checked inside and apart from two small ferrite beads to remove RFI, there is no protection whatsoever. Both the router and the video capture box could be destroyed by feeding them anything above 5.25 volts.

Wow, that should teach me to draw conclusions based on old computers. Looks like the industry has moved on without me.

[6502dude]

This entire thread has been somewhat convoluted with AC vs. DC, regulated vs. unregulated, and then comparisons to Vic-20 or other Commodore power supplies.

The original question was:
Original Supply
Input: 120V AC 60Hz 23W
Output: 9.5V DC 1.5A


Replacement Supply
Input: 120V AC 60Hz 15W
Output: 10V DC 0.85A

Likely the replacement power supply will not meet requirements. Find a comparable unit which is 9.5V to 10.5V with the ability to supply 1.5A or above. Make sure the polarity of the plug matches your requirements (gnd on center or sleeve conductor).

If you can not find an adapter locally, and are willing to pay postage, I will look through my transformer collection and send one.

Actually, if you are absolutely certain your power adapters use transformers and are not switching devices, you could actually plug them both in series and there is a great deal of chance that it would work and it would be safe.

This is pretty basic stuff.

If you have two transformers that are wired in series, with equal turns ratio between primary & secondary for each transformer, then you can pick off the desired voltage the secondary from one of the transformers.

If you wire secondaries in series as well, you can have double the secondary voltage (with advantage of a center tap at zero volts), assuming you the transformer windings are wired in phase.

If secondaries are wired in parallel (once again ensure phase is correct between windings), you can have double the current capacity of each single transformer.

.......6502dude - no foot in mouth on power supply design

[Jeff-20]

Well I asked around on another board and got this reply:

I'll have to double check what supplies that I have. Basically I'd be using the cable from a Sega supply (that has the correct tip) and splicing the cable with a 3rd party supply that has greater amperage. I solder the cables & use heat shrink tube so it's well insulated & strong.

You don't actually need exact volts & amps. It could be rated at 1000 amps and it wouldn't make any difference - it only matters if it's less than required. Voltage can be anywhere between 8-12 safely. The power supply feeds an internal power regulator, and most regulators accept an input voltage of 7.5 to 48 volts.

I only bring this up because the likelyhood of finding an exact match - 9V @ 1.5A - is pretty unlikely. It would probably be more like 10V @ 2A or 9V @ 1.75A. I've actually made these for CDX units before. Haven't heard any complaints yet

Anyway, price would be $15 + actual shipping. The final product will probably be around 2lbs or so. It'll be tested on my CDX first, so it's guaranteed to work for ya.

Does this info conflict with what was previously said here?

[6502dude]

Well I asked around on another board and got this reply:

I'll have to double check what supplies that I have. Basically I'd be using the cable from a Sega supply (that has the correct tip) and splicing the cable with a 3rd party supply that has greater amperage. I solder the cables & use heat shrink tube so it's well insulated & strong.

You don't actually need exact volts & amps. It could be rated at 1000 amps and it wouldn't make any difference - it only matters if it's less than required. Voltage can be anywhere between 8-12 safely. The power supply feeds an internal power regulator, and most regulators accept an input voltage of 7.5 to 48 volts.

I only bring this up because the likelyhood of finding an exact match - 9V @ 1.5A - is pretty unlikely. It would probably be more like 10V @ 2A or 9V @ 1.75A. I've actually made these for CDX units before. Haven't heard any complaints yet

Anyway, price would be $15 + actual shipping. The final product will probably be around 2lbs or so. It'll be tested on my CDX first, so it's guaranteed to work for ya.

Does this info conflict with what was previously said here?

At the danger of saying WRONG , there are a couple of errors in the above.

I would not want to anywhere near a power supply that could deliver 1000 amps. .

Note, you can weld metal at 80 amps and above.

If your internal regulated voltage is 5vdc, then power adpater voltage between 8-12, seems ok. You will just produce more heat internally the higher you go above nominal voltage of the orginal wall wart.

Assuming heat sink on voltage regulator can handle extra heat dissipation, you should be ok.

Statement that most regulators will accept 7.5v to 48v is incorrect. Most comonly used are the 78xx series and they their max input voltage spec is 40vdc. Connecting 7805 to 48vdc will release magic blue smoke.

[Jeff-20]

THe same guy PMed me this info after taking a quick look at this thread (he's not a member on this board) (quote edited for length):

...The 48 volt remark is correct, but largely irrelevant because it was more of a hyperbole tactic on my part. I was making the case that there is/was a wide range of acceptable input voltages - save for the stiffening caps that are usually connected to the input side of the regulator which are probably 16v or 25v. A 40V supply would work... briefly... until those caps blew up.

A 5V power supply capable of delivering 1000 amps:

...Was another hyperbolic, illustrative example
...Probably does not exist, mainly because there would be limited practical applications
...Would not be dangerous to humans. Hey, a decent car battery can deliver that much power in short bursts, and it's 12 volts! I'll touch both terminals with my bare hands any day.
...And 5V is too little voltage to weld metal correctly - you'd have almost no weld penetration

The posts about regulated external supplies is, within the context of the CDX, largely irrelevant. The CDX uses an unregulated supply.

An analogy for amperage is: If you were thirsty for a glass of water, but a freshwater lake was the only available source - would you be forced to drink the entire lake? Nope, you'd drink only what you needed. Unless there was a Wii on the line, but that's a whole other story Hmm... too soon?

So there you have it... I see in that thread that you have tried splicing power supplies before - that website with the 9v/1.5A supply is a great deal. If I were you, I'd just buy that & splice it in. If the polarity is backwards, just reverse the wires - I've done it with many of my game systems. You should see the frankensupplies feeding some of my consoles

[carlsson]

How much effect is a typical household electricity central capable of? If you run an electric stove at maximum power on all plates and oven, does it draw about 6 kW? 9VDC @ 1000A would theoretically mean 9 kW, and it would be a monster transformer.

[6502dude]

My weld example was with me thinking of the two extermes 48V and supply with 1000A capacity.


Splicing connector which mates to your console with replacement wall wart is functionally fine. I have done this numerous times for friends with fried transformers in their wall warts.

[6502dude]

How much effect is a typical household electricity central capable of? If you run an electric stove at maximum power on all plates and oven, does it draw about 6 kW? 9VDC @ 1000A would theoretically mean 9 kW, and it would be a monster transformer.

In US & Canada, the high end for many residential AC power panels is 200A with 240VAC - 2 phase. This works out to 48KVA.

In many neighbourhoods, power is stepped down from 14.4KV to 240V by pole mounted transformers ("pole pigs") or by pad mounted transformers. I can't recall ratio of homes per pole pig, but I knew this at one time. Many of the pole pigs contained fluid/oil to cool them which contained PCBs (banned in Canada in 1980s).

[eslapion]

Well I asked around on another board and got this reply:

I'll have to double check what supplies that I have. Basically I'd be using the cable from a Sega supply (that has the correct tip) and splicing the cable with a 3rd party supply that has greater amperage. I solder the cables & use heat shrink tube so it's well insulated & strong.

You don't actually need exact volts & amps. It could be rated at 1000 amps and it wouldn't make any difference - it only matters if it's less than required. Voltage can be anywhere between 8-12 safely. The power supply feeds an internal power regulator, and most regulators accept an input voltage of 7.5 to 48 volts.

I only bring this up because the likelyhood of finding an exact match - 9V @ 1.5A - is pretty unlikely. It would probably be more like 10V @ 2A or 9V @ 1.75A. I've actually made these for CDX units before. Haven't heard any complaints yet

Anyway, price would be $15 + actual shipping. The final product will probably be around 2lbs or so. It'll be tested on my CDX first, so it's guaranteed to work for ya.

Does this info conflict with what was previously said here?

There are hyperboles but this is "generally" true. What the guy seems to mean is there are no problems if the "found in a pile of junk" power supply is rated for a higher current than the official requirements of the "device I want to make it work with". However, it can be a problem if the rating of the "found in a pile of junk" power supply is rated for less that the official requirements of the "device I want to make it work with".

Also, it is true that devices using an AC transformer do not require a very accurate voltage as the transformer is usually used to feed an internal voltage regulator which has a pretty wide input voltage tolerance.

However, in the case of the VIC and many vintage game machines, the voltage regulator is linear and that means, the higher the voltage you feed it, the greater the amount of heat it will produce. So if you feed it too low a voltage then the machine may not work reliably. If you feed it too much voltage, it might turn into a toaster.

We all know too much heat is what kills electronics inside our VICs...

Added edit:
As the guy also pointed out, if the voltage fed to the device is much too high, it could also destroy the filter capacitors.