×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Voltage Controlled Resistor

Voltage Controlled Resistor

Voltage Controlled Resistor

(OP)
Anyone,
I need a voltage controlled resistor that can produce 0 to 1M ohms resistence with 0 to 15vdc or 0 to 28vdc input power. Any suggestions? I heard FET can be used but how can I produce 0 to 1M?

RE: Voltage Controlled Resistor

Is the R supposed to be in the 15 -- or 28 -- volt or is this the control voltage ?

Can you tell me more about your application ?

<nbucska@pcperipherals.com>

RE: Voltage Controlled Resistor

please tell me more about the appplication..

dydt

RE: Voltage Controlled Resistor

Hi, you can use a fet as a variable resistance but its resistance changes with the drain source voltage as well as the gate source voltage.You could try using a cds photo detector but you will not get down to 0 ohms.

RE: Voltage Controlled Resistor

(OP)
The aplication is to replace the thermostat.
Simulate the circuit to act as thermostat, and for the sensor to read resitance of circuit(in replace of thermostat). The resitance of thermostat goes higher as the temperature goes down. The sensor reads resistance of thermostat as it varies and gives out its temperature reading.

Control voltage is varied from 0 to 15vdc and in return should produce variable resistance.
I know it won't output exact 0 ohms. it should produce 3k ohms-1M ohms versus 15VDC-0VDC or 28vdc - 0vdc.

Have anyone used Phillips Semiconductors N-channel field-effect transistor(PMBF4416)?

RE: Voltage Controlled Resistor

Could you tell me what circuit the thermistor operates
in ? Do you have FAX # ? mine is (303) 439-8651 ATT: NICK



<nbucska@pcperipherals.com>

RE: Voltage Controlled Resistor

i think you should be able to use a wheatstone bridge circuit...you just have to work around the values of the voltages and resistance you need...

dydt

RE: Voltage Controlled Resistor

What about a digital pot? Never used them so not sure they have that wide of a span.

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


Resources

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