i need a power pack that has 3.5, 4.5, 5.5, 6.5 volts(dc)
ranges that will be powered by a 12 volts dc power
i will appreciate if the circuit diagram is included

 

Whats the expected current draw? a rotary switch and some voltage regulators should do the trick if you want to keep it simple.

 

This crys out for a switching power supply, since a good design there will use minimum juice and create very little heat. 3V at 1A would be 12V @ 300ma at the battery.

 

the input current is .92A/12v
while the out put is between 300mA and 500mA

 

input current is 0.92A while that of output is between 300mA to 500mA

 

I'm currently playing with SMPS regulators. In 6 months I may have something I could recommend.

On the short term though...

Properly heatsinked, the LM317 can handle 1 amp. The TO3 case style can handle 1.5A. It will get hot, very hot.

You can use a series of resistors with switches across them to select voltages. Since you have 1V steps it should be easy.

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