Continue to Site

Welcome to

Welcome to our site! is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Power supply, Please help.

Not open for further replies.


Newbie level 2
Oct 13, 2007
Reaction score
Trophy points
Activity points
I am wanting to power a 12v computer fan for long periods of time seperate from the computer.
I have snipped the end off of a walkie talkie charger and ive been told not to use chargers but this cord was plugged into the base where you put the walkie talkies at, and i think the cable its self could be safe enough to power the fan.
On the plug-in thing it says
SIL Ac Adapter
Class 2 power supply
output: DC7.2v 180mA

I have tried it out and it works at the speed i want it to, but im wondering if it will be dangerous to leave it unsupervised for long periods of time?

If anyone knows a cheap way to power this that would be a big help.

I think it should be fine to operate the fan with that supply.


    Points: 2
    Helpful Answer Positive Rating
I think you could design a power supply with transformer, filter and regulator ic(like 78xx or 723) to get power required for driving the fan.
That will be the cheap but may not be as reliable as using an adapter.


yor computer has many 12V power supply. you can use one
you can always find one that is not in use ( the yellow wire)

but if it's not possible, the simplest way to do it is to buy or to make your own 12V dc power supply with transformer, a bridge, a filter and a 12V regulator

Dear Johnnyy,

Though your method is quite OK, and I am sure you willnot have any problem running even for long continuous hours. But I would like to add that a cellphone does not draw current heavily through the chargerso can be left unatteded, where as iam not sure how much current your fan draws. Just to be sure, open the protective (plastic) cover of your adapter if you find it getting hot. Or drill a hole or two in this for proper heat escape...

Then I think after this you will not have much prob even for continuous usage...
Ofcourse there is no substitute like having your own power supply...ontime hard work-lifetime enjoyment...!!!


i think u can built u r own power supply for dis purpose so that the required power is obtained so that u can leave the fan unsupervised u can design the power supply more than the rating requird by the fan.

hi dear,

check the attached circuit

Not open for further replies.

Part and Inventory Search

Welcome to