LM338T voltage regulator

Dear All,

This is abt LM338 but I don't see any related thread so thought of posting a new one.

I want to use this as a voltage regulator.. so connected it to a power supply of 15.75v and Vout 3.70v ( @ R1=100 & R2=180 ). But when Vin=17.75v Vout=4.63v and Vin=20.3v Vout=8.20 ( @ same resistor values ) . I think @ fixed resistor values Vout should be the same regardless of Vin.

Can some explain me why it is not ?

Thx.

How much load current? Is it on a heatsink?

I have just tested the Vout with a voltmeter, no heat sink.


thx.

Is it wired like this, including the capacitors?