How can I get my power supply to stop blowing fuses?

I built a power supply using a 25.2 volt 2 amp transformer to use for etching projects.  It worked on my test plate but then started blowing the 1 amp fuses I was using with it.  I switched to 2 amp fuses and it works but my transformer is getting too hot.  I have experimented with different amounts of solvent and different size plates, which definitely makes a difference, though my 1 amp fuses are at most lasting about 10 seconds.  I have read about building a control box with a halogen light and a variable resistor to control the amperage, but would it allow me to take some of the load off of the transformer?  And if it would work, how would I connect it to my power supply?

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If you test your system in a dry environment ,It will behave different in a liquid environment. Liquid magnifies the current flow depending on the size of your tank.

That's why you get electrocuted when you drop a hair blower in a bathtub instead of a zap when you touch 110 v ac hot wire.

you can add a limiting circuit before the leads touch the tank because a liquid container acts as a capacitor (or step up transformer) drawing a lot of current therefore overloading your transformer

iceng5 years ago
A circuit diagram would be a help to determine where to  reduce your load.

Otherwise look for a shorted diode or a damaged transformer winding.

The control box sounds like it acts as a series resistor to reduce current.
This will also reduce the  output of your etching current.
Is that what you want ?

Nordovita (author)  iceng5 years ago
I don't have a diagram, but I here's a link to the power supply I put together. I am not using it for small knife etching, but for etching 5"x4" plates in a small tank. I figured it would work because before I was doing the same thing with a DC wall plug that I had stripped the ends off of and it worked fine but took forever.

A diagram for the control box can be found a bit down the page here.

I understand that reducing the current will reduce the output of my etching current, but I don't think that it will create any major problems. I am primarily concerned with figuring out why I keep blowing fuses and if adding a control box is going to what I'm thinking, which is to back the load off the transformer and give me some control over the amperage. I should add that I really have no idea what I'm doing, but just kinda went for it see how much I could learn.
iceng Nordovita5 years ago
Here is how it hooks up.

And BTW the reason your plate system is pulling more DC current is :
The solution changes as it is used and permits a higher current to flow.

Nordovita (author)  iceng5 years ago
Thank you, this makes it very easy to understand how to put this together. Will this reduce the load on the transformer though? Or will it only reduce the current flowing in the tank? What rickharris posted below also makes sense to me, so I am still not quite sure how to approach this.
iceng Nordovita5 years ago
By reducing the tank current we also reduce the load on your transformer.

Rick posts the truth !

This picture is the simplest reduction method I know.
  • The  40 Watt  is the highest resistance.
  • The 100 W is the lowest series resistance.
You can adjust the resistance by simply changing a light-bulb.

Your fuse blows because your drawing more then 2 amps from the power supply simple as that.

Your transformer gets hot  because your drawing too much current from the power supply.

You can change what your doing to draw less current.

Adding a big bulb may make less current available for your work BUT will still try to draw a large current from the power supply - ALL current  in the circuit adds together.

You need to limit the amount of current the power supply will provide electronically to less than 2 amps.

current limiting circuits

Nordovita (author)  rickharris5 years ago
This is very helpful. I understand what you are saying but these circuits are still a bit over my head. I do feel like I am going in the right direction though so thank you.
You have no current limit, and are exceeding the limits of the fuse.

You HAVE to add a "control box" to LIMIT the current to what your transformer can stand. The transformer doesn't have anyway to limit the current to "2A"