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Here is my schematic that I've designed, this is basically a 3 pin blinker device which will blink Bulb/LED.

Pins: 1. Supply 2. Ground 3. Load

Load will have bulbs/led connected. In this there is a toggle switch at Load, when turned ON, will sense the ground if bulbs are connected to load. If controller does not get ground, it will not give any output as load is not present. Bulb being a filament and resistor like, it will get ground. but in case of LED, i cannot do that. Is there any way to detect LED as in case of bulbs?

main factor of implementation is to start blinking only when the load is present. enter image description here

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  • \$\begingroup\$ I don't apprehend the purpose of all this. My first thought was like detecting if a car's headlight was burned out, or not, and providing an indicator if it was. But that doesn't appear to be the case, 2nd skim. I'm unsure about the application details, so I'm leaving this for others who may read better between lines than I do. \$\endgroup\$
    – jonk
    Commented Jul 5, 2020 at 21:07

1 Answer 1

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Your LED load will have a series resistor to limit the current through it.

You can therefore detect if (a) the series resistor has a voltage drop across it or (b) if the resistor/LED_Anode voltage has fallen below a threshold level.

Both can be done with a comparator or, more easily, with an ADC if there's one within the microcontroller your schematic half-shows.

The sequence would be:

(1)  Turn LED driver ON,
(2)  Measure voltage at LED_Anode through ADC,
(3)  If ADC result too low, turn LED driver off and complain,
(4)  Proceed with flashing sequence...
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