So I need to use an Arduino to detect wether a momentary switch is open or not to control multiple leds on the same hardware as this momentary switch and also to control another light. The circuit in the image is a recreation. The circuit must run on 9 volts. Right now it has a current of 13-14 mA. Here is a link to it: British Rail Class 150 Door Open Button. GWR/FGW. Great Western. | eBay
I wasn't sure about wether to use resistors or something like as wouldn't it lower the current? Thinking about using an optocoupler but I can't find one suitable for 9v @ 14mA
The white wires circled in red are the ones where the voltage should be lowered/isolated.
Sorry if my question is a bit confusing, please ask if you need clarification.
Here are some Over Voltage Protection Circuits.
You can increase the current limiting resistor to between 1K and 10K, since the Arduino very-high input impedance..
...Or, the Arduino ATmega chip already has built-in low-current protection diodes so just a 10K series resistor should be safe.
the current limiting resistor cannot be removed as it is part of the button pcb which I can't access without breaking it, and if I were to use a 10k resistor, would it be safe to just have the Arduino and go straight back into the battery negative?
like this?
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