×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Jobs

Resistor Choice

Resistor Choice

Resistor Choice

(OP)
Good Morning,

I am trying to find a resistor that will heat up and stabilize quickly ie within minutes. At the moment I am using an Arcoil resistor which at 10W is taking 3 hours + to get to a stable heat while well insulated.

I want to heat a copper block 50mm x 50mm x 25mm so that I can put a heatsink on the top for testing.

Any advice will be greatly appreciated.

Pete

RE: Resistor Choice

A PTC thermistor heats until it reaches a certain temperature and then stays there. You may need a series resistor so it doesn't "lock" in a low current state. GIYF!

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Resistor Choice

Have you considered a resistor, a sensor and a PID controller? It will stabilize much faster and may give a more accurate temperature.
If you want a steady flow of heat instead of a steady temperature, then use the PID setup and an over voltage to bring the temperature up fast, and then cut the voltage back and bypass the PID controller.
The copper block and resistor combination will have a thermal time constant which may be the factor dictating the warmup time.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Resistor Choice

Pete,

Think low-mass for your resistor. At 10W, though, it'll be hefty. The one you have is a good choice I think.

As Bill mentioned, it's when you add that copper block into the mix that the time constant gets up there.

Solution: many more watts and a good controller to avoid overshoot.

Best to you,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

RE: Resistor Choice

(OP)
Thank you for your input... much appreciated

RE: Resistor Choice

No need to use a resistor and a PID controller. Just attach a power transistor to the copper block and use a combination of zener and NTC to control the gate (or base) and let transistor loss be your heat source. Add a potentiometer/rheostat for variable temperature. That keeps temperature decently constant also when ambient changes. How constant do you need to keep temperature?

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

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!


Resources