Homemade Isolation Transformer
I have always wanted a second isolation transformer. I had some spare parts lying around and an old Atx power supply case. Using these parts I built my own. This one can be turned on and off and has a resettable fuse.
I cut out the front and fasten an AC outlet to it. Then installed a resettable fuse where the cooling fan was.
Next I put in the isolation transformer itself and soldered everything together. The on an off switch and the AC mains plug was already there so I use of it.
Here is the back of it.
Here it is turned on and it works great.
This article was prepared for you by Mark James; Pennsylvania U.S. Mark is a computer Technician and electronics hobbyist. Holds two associate degrees one in Computer systems technology and one in electronics engineering technology.
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Note: You can check his previous repair articles on How To Build A Dummy Load For ATX Power Supply Testing
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Parasuraman S
August 17, 2024 at 10:58 am
A must for our service table! Good work!
Mark J
August 18, 2024 at 1:43 am
Parasuraman S Thank you.
Albert van Bemmelen
August 17, 2024 at 3:11 pm
I hope that the power your transformer can handle is sufficient for your needs.
In the past I was lucky to be able to buy a heavy 320VA hospital isolation transformer with build in 16A automated fuses that was used but in excellent almost as new condition for a very acceptable price. Type KLMX/S from Helsinki Muuntosähkö 50/60Hz 220-240V ~ Pin 350 Watt (1,8A). And a friend was also able to buy one too at that time.
Carlo Alberto
August 21, 2024 at 3:32 am
Albert, I'm agree with You! Often these transformers are undersized compared to the declared currents (on the label) and end up causing problems instead of solving them! Unfortunately, good transformers are always expensive .... Bye!
Yogesh Panchal
August 17, 2024 at 4:17 pm
Good JOB! Mark
Maurizio
August 17, 2024 at 6:25 pm
Hi all,
I have got an odd story with a German purchased isolation transformer, which I use as safety mains for checking my repairs. As the main purpose of an IT is to provide a floating AC, I was frightened to discover that the secondary side had a factory ground wire! In my opinion, this add had been frustrating its safe use.
Of course I had detached that ground wire. Was I right?
Anwar Yunas Shiekh
August 18, 2024 at 2:20 am
I don't see an issue with having a ground,
Parasuraman S
August 18, 2024 at 6:36 am
I do not think providing a factory ground wire would hamper our trouble shooting. In fact, in my transformer, the IN ground (third point of AC inlet) is carried forward to the front to enable a common ground. I think it is safe to have the ground especially to avoid hum noises and 50Hz interferences. Moreover, the ELCB would trip incase of a leakage current to the ground. (Perhaps you might already know that the Neutral wire is actually a 'ground' wire at the power generating point) Let experts like Albert offer an opinion!
Hollis LuQuette
August 18, 2024 at 10:32 am
Maurizio,
I have a partial answer for you, here in the USA we have 110 volts on our benches for the most part . Which is actually 120 or 125 volts . 110 is the common number. We have LINE, NEUTRAL and earth ground, which is the bare wire in our Romex house wire. In our isolation transformers there are GREEN wires, those are EARTH ground wires. My Isolation Transformer came from a medical clinic. That type of Isolation means Isolation for NOISE and possible spikes. In order for my IT to be a TRUE IT , I had to take all the green wires out of my IT. That way all reference to EARTH ground is GONE and it is a true IT .. 2 wires in 2 wires out ........
Mark J
August 19, 2024 at 12:11 am
Hollis LuQuette I agree with you. There should be no reference to earth ground.
Mark J
August 24, 2024 at 7:35 am
Yogesh Panchal Thank you.
Anwar Yunas Shiekh
August 17, 2024 at 10:30 pm
How many VA?
Mark J
August 18, 2024 at 1:42 am
Anwar Yunas Shiekh It is 200Va.
Waleed Rishmawi
August 20, 2024 at 4:50 pm
a very important device for every technician to have on his bench. thanks for sharing and have a blessed day
Mark J
August 21, 2024 at 3:21 am
Waleed Rishmawi your welcome. You have a great day to.