Contact US

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!

*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

Bench top power supply problem

Bench top power supply problem

Bench top power supply problem

I received my 60V 5A bench top power supply through the post today, but how it behaves is really different in comparison to other ones I'm so used to.

For example, if I ever wanted a 12V output, I would get a 12V output. With this one, however, I have no control over the voltage what so ever.

I can only adjust the voltage when it's unloaded. When I connect it to a device, the voltage will plummet and stay fixed. I can only adjust the current.

I wanted it for my motor builds, but if I have no control over the voltage it's useless.

Any suggestions?

RE: Bench top power supply problem

If it has sense terminals, they must be connected to the related outputs, by either a resistor or a short.

More likely, it also has foldback current limiting, and either the devices you are connecting draw too much current for it to supply, or you need to crank up the current limit setting a bit to feed them.


Mike Halloran
Pembroke Pines, FL, USA

RE: Bench top power supply problem

There ain't no technical data in the page you referenced.
Actually, there is a little, but not a lot.
Didn't you get a user manual?

Never mind.  It's a 'lab' supply, which means that the foldback is very fast.  That means that it won't start, e.g., a 12V/5A motor, though it could keep one running if the motor was already at rated speed when you connected it.

I.e., the supply will deliver up to 5 amps, with the current control dialed to the max.  If your load attempts to draw more than 5A, the supply will shut down almost instantly, to protect your load and itself.

What are you trying to drive with it?  Voltage?  Rated current?  Starting current?

Mike Halloran
Pembroke Pines, FL, USA

RE: Bench top power supply problem

There is a manual, but unfortunately it's all in Chinese.

It's for my motor project which hasn't been built yet. I wanted to drive it upto speed with the 60V as well as have some speed regulation.

So basically, this isn't going to work for motor projects?

RE: Bench top power supply problem

For small motors, yes.  You haven't told us how big yours is, or will be, in terms of current or power.

My first encounter with 'lab' supplies, many years ago, involved a 12VDC linear actuator that had a nominal current rating around 10 or 20 amps.  It ran great from a car battery with a contactor to start it.  

My incoming QC department reported the actuator as 'dead' because their lab supply couldn't deliver the 275A or so that the motor needed for a millisecond or two to get started.  The supply turned itself off so quickly that the motor didn't even twitch.

So, go get 5 old car batteries.

Mike Halloran
Pembroke Pines, FL, USA

RE: Bench top power supply problem

Similar looking supplies from China are rated 30V 3A.

Just because it states that it is 60V 5A does not mean it will do both 60V and 5A. It might do 5A at 12V, and only 1A at 60V.

RE: Bench top power supply problem

My supply is a constant current source. I didn't no they came in so many different 'flavours'.

BK Precision (expensive!) have a nice document to read on their power supplies. I need a 'Battery Eliminator,' constant voltage source or a constant voltage/constant current source not a fail safe 'lab' supply.


RE: Bench top power supply problem

I think you just have the current limit set too low.

RE: Bench top power supply problem

Correct its just in "constant current" mode instead of "constant voltage" mode.
The LED near the current knobs should be illuminated now.. You want to get the other light to turn on..

Typically you just turn the power supply on (without any leads/loads hooked to it) and then turn the current knob all the way up. The voltage light should then illuminate and you are in constant voltage mode and should be good to go.

And yes as comcokid said pay attention to the wattage rating.. Many times they state 60V 5A.. But then state like 150W max or something like that.. So you can do 30V@5A (150W) but 60V@5A (300W) will be over its rated wattage limit.  

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! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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