Activate a Relay at 0.5 V

6 11

Reply | New topic

#1 21673391 12 Feb 2015 19:12

Dale Stieg Dale Stieg

Anonymous

Post #1
21673391 12 Feb 2015 19:12

I'm working on an automotive project and want to take the voltage signal from and oxygen sensor (which puts out .2v -.8v) and trip a relay at .5 volts to drive a small 12v motor (like a windshield wiper motor)

Can I accomplish this without an expensive programmable relay?

Dale
ADVERTISEMENT
#2 21673392 14 Feb 2015 18:56

Peter White Peter White

Anonymous

Post #2
21673392 14 Feb 2015 18:56

Take the output of the O2 sensor to a voltage network that increases the 0.5v to about 0.7v and then drive a transistor.

It all depends on the current available from the .2v to 0.8v output
ADVERTISEMENT
#3 21673393 15 Feb 2015 15:09

Abdur Rehman Abdur Rehman

Anonymous

Post #3
21673393 15 Feb 2015 15:09

If you're going to do more than just tripping a signal - I recommend a PLC (or HMC) solution by Maple Systems http://www.maplesystems.com/ - the 7030 units cost $400...
#4 21673394 25 Feb 2015 03:34

Frank Bushnell Frank Bushnell

Anonymous

Post #4
21673394 25 Feb 2015 03:34

This can be done with simple electronic circuit, using a comparator IC and a transistor to drive the relay.
#5 21673395 25 Feb 2015 03:39

Peter White Peter White

Anonymous

Post #5
21673395 25 Feb 2015 03:39

You don't even need the comparator. Just put a "set"on the transistor.
ADVERTISEMENT
#6 21673396 25 Feb 2015 04:39

Frank Bushnell Frank Bushnell

Anonymous

Post #6
21673396 25 Feb 2015 04:39

My idea with the comparator was to give a clean on/off for the benefit of the relay, rather than just a transistor that would gradually turn on as the signal voltage rises.
ADVERTISEMENT
#7 21673397 25 Feb 2015 04:53

Peter White Peter White

Anonymous

Post #7
21673397 25 Feb 2015 04:53

So what, if the transistor turns on slowly. They relay turns on. We are not making a project for the LUNAR LANDER
#8 21673398 03 Mar 2015 10:36

Dale Stieg Dale Stieg

Anonymous

Post #8
21673398 03 Mar 2015 10:36

Thanks for the reply. I'm not an electrician. What is a "set" on the transistor.

Can you provide a simple sketch of the circuit that I could put together from components?
#9 21673399 03 Mar 2015 10:38

Dale Stieg Dale Stieg

Anonymous

Post #9
21673399 03 Mar 2015 10:38

Thanks for the reply. I'm not an electrician.

Can you provide a simple sketch of the circuit that I could put together from components?
#10 21673400 03 Mar 2015 11:29

Ruben Proost Ruben Proost

Anonymous

Post #10
21673400 03 Mar 2015 11:29

A germanium transistor only needs like 0.3V
#11 21673401 03 Mar 2015 15:17

Peter White Peter White

Anonymous

Post #11
21673401 03 Mar 2015 15:17

There are 3 ways to connect the O2 sensor to an amplifier.
You have to know the output impedance of the O2 sensor to be able to decide on which arrangement will work.

You can offset the transistor with a Schottly diode, use a germanium transistor or provide a voltage divider.
#12 21673402 04 Mar 2015 07:45

Jens Grabner Jens Grabner

Anonymous

Post #12
21673402 04 Mar 2015 07:45

The difference between Schottky-Diod and Si-Transistor is ca. 0.35V.
Create an account, log in here. You will receive points by participating in discussions.
Join this discussion.

Install Elektroda application

Didn't find an answer? Ask Artificial Intelligence

*I agree to send the question to OpenAI, Anthropic PBC, Perplexity AI, Inc., Kagi Inc., Google LLC - owners of language models in order to prepare the best response. The companies may monitor and log information entered into the form.

*I agree to publicly display my question and answer. The question and answer will be publicly available to everyone. The process may take a few minutes. Upon completion, you will be redirected to the page with the answer.

Wait...(2min)

Reply | New topic

Report a violation of the law

Activate a Relay at 0.5 V

Didn't find an answer? Ask Artificial Intelligence