78Views5Replies

Author Options:

3v Relay Module and PIR sensor circuit troubleshoot Answered

​Looking for help on my project.  See image.  Testing before connecting to high voltage device.  Using a 3v relay triiggered by the PIR signal.  As you see wired now, There is no ground wire coming from PIR.  The circuit would not trigger relay with a ground wire to the PIR.  When this does trigger I noticed on the relay that the LED would not go completely off.  So I check to find that when relay turns "off"  the PIR is still sending 2.8 volts to the relay.  Not enough to trigger the relay, but enough to show power through the LED.  Obviously something wrong here where the PIR or Relay are still drawing power.  Can you help?

Discussions

0
None
gmoon

3 years ago

Why is the PIR module not grounded? More detail about the relay module inputs would be helpful, too.

0
None
DiyWaterDoggmoon

Reply 3 years ago

With the ground connected the relay will not trigger. It appears with the ground there isn't enough voltage to drive relay. Only the indicator light on relay will light very dim.

0
None
gmoonDiyWaterDog

Reply 3 years ago

It likely won't work correctly until the modules are wired as recommended. That includes providing the relay module with the correct voltage.

For some logic (@ 9V) 2.8V IS a low (off) signal. You need to use the correct voltage for all the different components. And have a common ground.

0
None
DiyWaterDog

3 years ago

Thought this drawing might help better than my wiring image.

Again note... their is no ground coming from PIR. This circuit triggers
relay, but there is a constant 2.6 - 2.8 volts going to relay after the
relay switches off from the allowed time from PIR. This keeps the
light indicator on the relay dimmed. I am guessing there should be 0
voltage with no light. Hope somebody can help.

PirRelay Drawing.jpg