I want to build a power supply (I know buying one is cheaper) and I'm not using a computer ps because I already have one. The project:
Output with a range from 3 volts to 30.
I will add 2 digital panels to read amps and volts.
What I need;
Transformer (need specs here)
Voltage regulator (LM317?)
Can someone design a schematic for me with all the values and what I need?

 

here is a 1.2V to 30V, just choose the transformer to suit your design, lower R1 to 150 ohms,to increase output voltage.


http://www.eleccircuit.com/my-first-variable-dc-power-supply-1-2v-to-30v-1a-by-lm317/

 

here is a 1.2V to 30V, just choose the transformer to suit your design, lower R1 to 150 ohms,to increase output voltage.


http://www.eleccircuit.com/my-first-variable-dc-power-supply-1-2v-to-30v-1a-by-lm317/

I will try that one and I will add the amp and volt digital panel.
Thanks

 

They show the common connected to earth ground, you may want to float it if a bench supply?
Max.

 

The amount of output current you want will determine the size of the heat sink you will need for the LM317.
For example with a 1A output at 3V and a 35V source, the power dissipated by the LM317 is 32W, which requires a large heat sink. For that you might consider adding a cooling fan to reduce the size of the sink or a heat sink with a integral fan like those used for cooling PC processor chips.

The transformer should have a current rating about double of the maximum DC current you want.