How to Design a Variable Voltage Regulator Circuit?

Naveen Mathur's picture

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Joined: Aug 10, 2018

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How to Design a Variable Voltage Regulator Circuit?
August 10, 2018 - 6:55pm

Hi, I want to make a regulated power supply circuit for my project. I also want to vary that regulated ouptut as per requirement. I have a 12V, 1ampere center tapped transformer. Will you provide a circuit diagram for the same.

Thankyou

John_Kripto's picture

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Joined: Aug 11, 2018

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Use a Rectifier and a LM317 Circuit
August 11, 2018 - 2:12pm

You have specified that you have a Centre trapped transformer of 12V and 1A and have asked for a Variable regulator circuit. But, you have not specified what is the required output range. So I have assumed the transformer to be a 12-0-12 Center trapped transformer and you are expecting a variable output voltage from 0V to 24V.

In that case you can use a diode bridge to convert the 24V AC (combine two 12V wires) to DC and the regulate to using the LM317 Variable voltage regulator circuit. The circuit diagram for the same is give here, just ignore the en-circled parts for you will not be needing it. Using the circuit you can regulate the voltage from 1.25V to 24V with the current limit of 1A.

The circuit was clipped from this tutorial, you can read it if you want to understand how the circuit works.

 

Naveen Mathur's picture

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Joined: Aug 10, 2018

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Yipeee.. I am getting
August 14, 2018 - 12:48pm

I tried your circuit and after spending some time I am successfully getting the variable regulated output now. Thank you John for your reply.

Hiro_Hamada's picture

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Joined: Apr 17, 2018

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How did you connect your center tapped transformer
August 15, 2018 - 11:26am

Hi Naveen, I am also trying to build a small adjustable power supply for powering my future electronics projects. But I do not understand how you used that circuit.

I am also having a center tapped transformer that is rated as 12-0-12 with 1A output current. In the circuit  diagram given by john there are only two wires coming out of the transformer whereas mine has three. 

Please tell me how to connect these three wires according to the circuit diagram?