Here’s a circuit for simple Adjustable voltage regulator power supply circuit, at use integrated number circuit TL431. By from the circuit can fine volt 3V – 30V, depend on feed volt supply input and change the value R2, R1. This is the figure of the circuit;
It follow a formula calculates Vout = (1+R1/R2), Vref = 3V-30V, but this circuit gives current get not tall 100mA only. It just if want to enhance current, must use the transistor helps to enlarge current, such as 2N3055, TIP41 numbers or the other.
