This is the Shunt Regulator circuit using TL431 —voltage Reference – Shunt Voltage Reference IC.
They are easy to use, comprises one IC, three resistors, four capacitors.
If you like to use Zener diode for the voltage reference, it very cheap but low quality than the IC.
In the circuit…
the output is 5 volt 15mA, if you other voltage can change R2, R2.
The C1, C2, C3 use for filter the volt, low noise ripple.
Adjustable Regulator circuit using TL431
This is 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. 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.
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