Products:
Arduino Mega 2526 Rev.3
Opamp OP37E
Relay: iRhapsody 12V 80/60A 5 pin SPDT
I’m feeding the ~5V output to the opamp and I am getting 8V output. The relay’s trigger, or cut in, voltage is ~7.5V, but for some reason the SPDT doesn’t switch. I even put the opamp into saturation mode and got 12V on the output and the relay still didn’t trigger. DMM shows 40 mA from output to ground. Any ideas?
Show us a good schematic of your circuit.
Show us a good image of your ‘actual’ wiring.
Give links to components.
Posting images:
https://forum.arduino.cc/index.php?topic=519037.0
From your schematic I can see that it is an interesting circuit, not well designed. The OP37E is not a relay driver as the Arduino a Power Supply it is NOT. The output stage has good load driving capability. A guaranteed swing of 10 V into 600 Ω and low output distortion make the OP37 an excellent choice for professional audio applications. Explain what saturation mode is for the OpAmp? Why not use a simple MOSFET or transistor circuit, from what you say an OpAmp does not appear to be an appropriate choice. Consider doing a few tutorials on analog circuits and op amps, hopefully you will understand what I am trying to say.
That relay has an 80 Ohm coil, 150mA @ 12V, a 2N2222 NPN transistor with 270 Ohm base resistor should work.
Thank you all for you’re replies! We’ve decided to swap the opamps for boost converters.
As far as what saturation mode is, it is where you bias a transistor such that it acts like a short circuit. If you’re curious, here is the data sheet.
https://www.digchip.com/datasheets/download_datasheet.php?id=723667&part-number=OP37E
Why boost converters in place of op amp ?? Seems odd choice
jdba249:
Thank you all for you’re replies! We’ve decided to swap the opamps for boost converters.
What? What was powering the opamp before?
Do you have a 12V power supply able to drive the relay? If not why not get a 5V operated
relay instead? It makes no sense at all to use an opamp as a driver, opamps are analog,
relay drivers are switches. Not related.
If you do have 12V supply, the circuit in post #3 is a good choice. If you need to add a
12V supply, the circuit in post #3 is still a good choice.
Why not simply purchase a relay module, it has isolation, driver, etc already on the board. They cost less then $10. and are designed to work with the arduino.
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