O/P voltage variable using LM317?

Hi

I am trying to design my own trimmer adapter. Its rating are:

15 V dc ≡ 5.4 W

The Philips trimmer can operate while charging and on battery after charge. I am trying to obtain 15 V dc using IC LM317 (Adjustable Voltage Regulator) using the design provided in its datasheet. I simulated the design using Proteus but on varying the load using a potentiometer, the output voltage fluctuates and also the current is very low (approx. 0.0029 A) while the required is(i think) equal to 5.4/15 = 0.36 A. How do i obtain that much current for a load battery of resistance ( 15/0.36 = 41.67 ohm)?

Is the LM317 unregulated? If yes, how do i implement my little project?

Here is the link for proteus design file(*.dsn) : https://drive.google.com/file/d/0BxBeO_ZsHganYXBJNEhocF83dEk/view?usp=sharing

I am also attaching the *.jpg file for the same design.

Kindly help me regarding the same.

Thanks & Regards

Dev

Hi Dev Vaibhav,

I think the output voltage is fluctuating because your input isn't properly filtered.
Try replacing the AC supply and full-wave bridge rectifier with a DC source first and see what happens.

Hope this helps.

Regards,
Justin

Hi Dev Vaibhav

Lm317t max safe v in put is35v it will work still above 35 voltage also but it is not safe

lm317 can deliver a max of 1.5 amp of current even at 1 amps it starts to heat up

so transistors are used all most parallel to lm317t tolimit the current flow though it.

preventing lm317t from heating up. see my attachment this will help you.

. the in put v must be 3volts above the required out put voltage.

pl review my rating.

Regards V.Sambath kumar.

Thanks Justin !

I replaced the transformer and bridge with dc supply and everything worked fine which means that it was a problem of filtering (Yes, you were right). Then i tried changing the filter capacitor i.e. c3 to 470uf and with a 220 V to 25 V transformer, the simulation results are good too Let me implement it practically and i will update the same...

Thanks a lot....

Regards
Dev

Thanks Sambath !

That is an improved and generalized design. Thanks for it. I will try to design and implement it and tell you the updates.

Thanks and Regards
Dev

Hi...

I just checked the circuit on breadboard and things seem OK for now. Will update when i check the o/p voltage on CRO (sorry, today's my college holiday).

Hi Dev Vaibhav,

Thank you very much for your reply ,

Keep in touch Good Luck.




V.Sambath kumar.

Hi

Made the PCB and the circuit gives the required output. Though my trimmer requires service :)

Thanks
Dev

Hi DEV VAIBHAV,

Thank you you very much for your feed back.



Regards V.Sambath kumar.