Sunday, April 15, 2018

Bench power supply ( part II )

After part I, here's part II for the conclusion of the bench power supply.

It's a dual adjustable power supply based on LM317 and LM337, 3 terminal using adjustable positive (LM317) and negative (LM337) regulators.

Basic circuit is this one after some changes on the original one and it's similar to the ones on the datasheet of the regulators:

And the finished product in the box, the right half of the box with voltage meters displaying output voltage.

The lower voltage meter although showing a positive value is measuring the negative part of the circuit. From white post (0 V / GND) to black one (- V).
I can enable the main power output on the left only also (part I blog post):

or both at the same time:
 For the USB output, in the middle, there's no need to measure since it's allways 5v and it's allways on.

Inside the mess looks like this:
 The smaller transformer is for the dual supply and the big one to the single output.

 The meter modules on the panel (small green pcb), are feed from the output at the binding posts, so, with voltages lower than 4.5V approx will go blank.

Have a great week!

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