stray five volts
Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=135783
Printed Date: May 03, 2024 at 9:31 AM
Topic: stray five volts
Posted By: dgajp
Subject: stray five volts
Date Posted: January 11, 2014 at 6:39 AM
I designed this using relays I had on hand.to distinguish between negative and positive depending on probe input.except for unwanted 5 volts measured at probe , it works well.I could be better.
Replies:
Posted By: dgajp
Date Posted: January 11, 2014 at 5:30 PM
More Information
 
Posted By: oldspark
Date Posted: January 12, 2014 at 5:30 AM
What are you trying to do?
There is nothing there to distinguish between +12V or -12V since there are no diodes and no 0V.
You need to use comparator circuitry.
Posted By: oldspark
Date Posted: January 12, 2014 at 3:35 PM
PS - when you say +12V & -12V, is that a 24V supply, or do you mean +12V & 0V?
Also what is it probing - ie, it's not a logic probe for digital circuits or for some other low power output?
Posted By: dgajp
Date Posted: January 12, 2014 at 4:00 PM
+12v 0v .this is an experiment using relays.the tester is meant to distinguish positive wire from ground in a 12 volt circuit
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David
Posted By: oldspark
Date Posted: January 12, 2014 at 9:48 PM
Choose the right 12V relays - ie, turns off with less than 6-7V, then relay #1 85 to GND; Relay #2 86 to +12V, join Rly1 86 to Rly2 85 to the probe.
Rly1 is energised if the probe is +12V; Rly2 energised if probe = 0V.
Mind you, probe-wise +12V may mean +8V to 12V etc, and 0V may mean 0V to +4V etc.
Posted By: harryharris
Date Posted: March 07, 2014 at 6:43 AM
If you need to test POS and NEG sources make something up with a red and green 12V+ LED and some diodes, thus no draw and no harm to ECU based components also will cost pennies compared to what you've shown above.
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Test before boxing up.
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