laptop ac adapters

[tc2468]

anyone tried connecting laptop ac adapters in series or parallel or a combination of. I have lying around four identical 16v 4.5a adapters and was wondering if I could serial connect 2 to make 32v 4.5a and then parallel that to make 32v 9a.

these adapters use 2 blade plugs to house mains (isolated grounds?).
think this would be a reliable solution?

if this works ok it would be a cheap solution as these kinds of adapters are only a few bucks surplus or used.
would different types connected together work?

[smarbaga]

i have 2, 24v sola din mount switching power supply's.
i called sola to see if i can series the 2.
the guy at sola told me not to do it.
i asked him about using blocking diodes between the 2 units.
he still said this will still blow the 2 units instantly.
but ths doesn't mean it will not work in your case.
thats all i can say about it.

[Pandinus]

Putting switching power supplies in parallel isn't the greatest idea, basically they wont be at EXACTLY the same voltage... so they will fight each other trying to make each others voltage match. When a load is placed on them, the one with the highest voltage will be doing all the work until it is overloaded and shuts down.

You could put a balancing resistor on each power supply, 4.5 amps... say a ONE Ohm 25Watt resistor on each supply would drop a max 4.5V. You could go with a smaller value resistor, but your wattage goes up... .5ohm would need a 50 watt ... or two 1ohm 25W in parallel. What this does is allows both power supplies to put out a slightly different voltage and current through its resistor without fighting each other... the summed current goes through your final load.

If you put them in series, as long as the outputs are fully isolated from the AC inputs they will most likely work... it depends on the switching method... if there is a transformer that is switched on and off at high Frequency the outputs will be isolated, but if the AC is rectified and then the current switched on and off through an inductor, then the outputs will not be fully isolated... In house wiring, Ground and Neutral are essentially the same voltage potential... zero. The only difference is the neutral has current flowing through it from the hot, while the ground should have no current passing through it as it is just a safety of sorts. The current passing through the neutral causes a small voltage drop which could translate into interference in a circuit, so the ground lead can keep the chassis of a device at a safe level as well as be used to dissipate RF interference.

[tc2468]

I actually tried 2 of the laptop adapters in series and it worked - 32v.
My other PS blew out while testing some stuff and I wanted to continue playing around with the drivers/motors.

The other PS that I have (salvaged from a very old early 90's scanner) I cannot get to work. Sola Electric 39-183, maybe there needs to be a couple wires shorted (original power switch?) to get it to work. I couldnt find anything googling on this unit, a schematic would be awsome.


thanks for the comments

Tom