Very sensitive dim led indicator detector
This is a working circuit (I ordered and received some QSD2030 photodiodes). My test light is a 40+ year-old red LED with 6 mA through it. It is very dim compared to modern LEDs.

I can't absolutely guarantee that this will work for you, it will depend on the brightness of your indicator light and how well you can shield the sunlight. My test light (LED) is almost certainly dimmer than your indicator light. But, sunlight is very, very bright, you will need to shield from sunlight very well.

If the photodiode is too sensitive, you can reduce the value of R1.

I recommend using a car USB +5V power adapter as the power source. It will probably work with 12V. But, car 12V can have nasty noise on it and the voltage can vary quite a bit.

Edit: If a low-power buzzer is used, the transistor isn't necessary. A CEP-2242 would be a good choice, it doesn't need a transistor. https://www.digikey.com/product-detail/en/cui-devices/CEP-2242/102-1115-ND

Or, you can search Digikey. You want an internally driven "indicator". If it is externally driven (speaker), you will need to add an oscillator.







simulate this circuit &ndash; Schematic created using CircuitLab