Linear Power Supply - Purchase, Variable Transformer, Transformer Array???

[chiques]

My goal is to have a linear power supply which with a (-) rail for the purpose of experimenting with battery charging and power amplifiers.

I have had unfortunate experience with switched power supplies because they are not very good when it comes to charging my high current batteries or heating element equipment.


I'm debating whether I should purchase a variable transformer, using an array of left over transformers in my lab or purchasing a power supply. Does anyone have any experience or opinions regarding my options?

Thanks for any guidance.

 

[abhi_tandon80]

what is your main purpose Battery charging or testing of amplifiers ? there are power supplies with two independent controls in single unit .

 

[chiques]

what is your main purpose Battery charging or testing of amplifiers ? there are power supplies with two independent controls in single unit .

Priority:

1. Experimenting with battery chargers
3. Power Amplifiers

 

[BradtheRad]

I made my homebrew power supply from a 12V 3A transformer, with center tap.
Ordinary full-wave diode bridge.
4,700 uF smoothing capacitor.

It is variable from 0 to 16V, by means of adjusting bias through a 2N3055 transistor. It is heat-sunk to the steel enclosure. It gets hot enough to burn my finger when I crank up the power.

The meter is switchable between showing volts and amperes.

I added a second adjustable supply in case I wanted to configure it for bipolar operation, or to obtain 6VAC for cooler operation at reduced volt output.
Mostly I just use it as a current-limited supply with a 220 ohm resistor screwed down against the post.

I have a 2.5 A variac which I have used a few times for odd purposes. But come to think of it, there would be nothing wrong with using it to vary the DC output. There would be no need for a transistor getting hot.

120 V at 2.5 A makes 300 W.
Going through a 12V transformer could conceivable deliver 25 A.

 

[Kuberkoos]

Have a setup more or less like BradtheRad,but I use the Variac (Var. trafo.) extensively. It works very well for me,