As a technician you have come across many transformers, First on the list is step down transformer which work is basically to step down voltages like 110Ac to 12Vac or 240Vac to 12Vac etc.
We also have step up transformer which steps up the voltage, a good example is fly-back transformer.
Another transformer available in the market is isolation transformer (this transformer has the ratio 1:1) which means if you give it 110Vac on the primary you will get 110Vac on the secondary side. Give it 240Vac on the primary and you get 240Vac on the secondary side.
So what is the purpose of using this transformer and get the same voltage (results)
This is where isolation (separation) comes in. this means even if the secondary voltage is still the same, it is not connected directly to the main supply but done in isolation (magnetically) so to speak.
I am not an electrical technician but I noticed that when wiring my house the neutral wire was actually connected to the earth wire(gnd) and therefore when you touch the live wire standing on the ground you are actually creating a very good return and hence electric shock is experienced (don’t try this)
After transformer the output voltage is not referenced to ground and therefore we can say there is isolation (separation) between the main and the equipment.
With that small introduction on isolation transformer let has see how you can make one yourself easily.
1. Transformer X 2
2. Fuse (2Ampere 250V)
4. Power cable
Someone said having an isolation transformer on your workbench is not a nice thing to have but a must thing to have in terms of safety it offers to the technician.
The most important and also expensive component when making this gadget is the transformer itself.
In choosing the transformer to use kindly take into consideration the transformer current rating (in my case I have used 24-0-24 and current rating of 5 Amperes).
As I have said you will need two transformer of the same rating, so you will need two like the one pictured below.
Now it is time to assemble the two transformers, the transformers are connected back to back and therefore the two secondary outputs are joined together as you can see in the picture below.
You will only need one pair of output and therefore you will leave one output from both transformers un- used and it is important to tap them as shown below.
Now you have again two sets of primary wire; one set will connect to the power cable and the other to the socket which in this case it isolated from the mains.
Let me mention also that it is important to have a fuse on the input side (like 2 Amperes fuse) for safety purposes.
With that you are now ready to test your isolation transformer and therefore you can connect a 100 Watts bulb at the socket and run it for some time and if the transformers are not getting hot then it means you got it right.
If the transformer is getting hot this could point to over load or the transformer is faulty.
After assembling you can also measure the voltage at the output as you can see on the picture above (expect 240 Vac or 110 Vac) depending on your outlet.
Below you can see the gadget with a 60Watts bulb
When you are happy with the testing you can now decide to make a nice housing for your project depending with your taste and you are done.