Hey,
The image attached is what I am currently using to sense the output from a relay (28V). These OptoIsolators are connected to GPIO pins so when the Relay is closed, the GPIO goes High providing me with positive feedback.
The problem I am having is that the Current Limit resistor plus the diode in the isolator are going to draw more power than I want. Plus the cost for the parts is much higher than I would like because the resistor is rated for 2 watts.
Is there some other way to sense this voltage and provide 5vdc to my GPIO when it is present that will cost less than ~10 dollars? The trouble is that I need to use this circuit several times which makes the price go up rapidly.
The image attached is what I am currently using to sense the output from a relay (28V). These OptoIsolators are connected to GPIO pins so when the Relay is closed, the GPIO goes High providing me with positive feedback.
The problem I am having is that the Current Limit resistor plus the diode in the isolator are going to draw more power than I want. Plus the cost for the parts is much higher than I would like because the resistor is rated for 2 watts.
Is there some other way to sense this voltage and provide 5vdc to my GPIO when it is present that will cost less than ~10 dollars? The trouble is that I need to use this circuit several times which makes the price go up rapidly.
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