Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


cheap solution on AC power regulator

cheap solution on AC power regulator

cheap solution on AC power regulator

Hello everyone,

The unregulated output AC power is from 22VAC to 30VAC, 2.5A max, but the input voltage range of the load is 22VAC~28VAC, load may demage when the power is over 28VAC.

Also, there is a motor inside the load and the motor is remote controlled, when it works, the un-regulated output voltage may drop to 28VAC, but it will go back to 30VAC when the motor stops.

Is there any way I can control the output voltage always safe---that means, when it's 30VAC, I can reduce it to 28VAC. When it's already 22VAC, don't do anything.



RE: cheap solution on AC power regulator

A crummy way would be to provide enough load to always keep the output below 28V perhaps a resistor.  (Horrible waste of energy.)

Or replace the transformer with one that has better regulation.

Or add an appropriate autotransformer to shave off the 2V without a lot of power loss.

Or buy the correct supply.

Keith Cress
kcress - http://www.flaminsystems.com

RE: cheap solution on AC power regulator

autotransformer to shave off the 2V without a lot of power loss is good.

would you pls explain it in detail?

RE: cheap solution on AC power regulator


Note that a normal transformer has to pass all the energy thru a magnetic structure. This makes a standard (fully isolated) transformer a certain size.  An auto transformer provides no isolation what-so-ever but this results in only a fraction of the power needing to pass thru a magnetic structure.  This allows them to be dramatically smaller than their counterparts.  Since you only need a 2V adjustment no isolation is probably needed.

Keith Cress
kcress - http://www.flaminsystems.com

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close