×
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

SPST relay replacement

SPST relay replacement

SPST relay replacement

(OP)
Hello everyone,

I want to replace some SPST electromecanic relays by something that would be less space and current consuming.  I found digitally controlled analog switches and Solid State Relays - which are working fine - but these are rather expensive.  I'd like to know if there is any other options that you people could think of.

What the relays are doing is simply open or close the loop for signal lines coming from a motor control module.  This module is somehow a "black box".  All I know is that square wave signals of 60Hz, 10Vpp are coming out and when a path is closed, a motors run.  I tried to use enhancement mode Mosfets but since I don't have a common ground reference between my circuit and the module, it's not working (i.e. the Drain-Source is always conducting no matter if a voltage is applied to the gate or not).

Thank you.

RE: SPST relay replacement

Look at reed relays some can be very small.

RE: SPST relay replacement

Optoisolator?

Wheels within wheels / In a spiral array
A pattern so grand / And complex
Time after time / We lose sight of the way
Our causes can't see / Their effects.

RE: SPST relay replacement

Hi,

Depending on the current requirments of you motor then what about an analog switch. See :-
http://dbserv.maxim-ic.com/tarticle/view_article.cfm?article_id=90

but remember these do have an on resistance (2 ohms & above) unlike your relay so if your motor draws lots of current then you may need to be prepared for smoke !!

Any help ?, yes no let me know.

Regards

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