AlbertHall
- Joined Jun 4, 2014
- 12,345
Does that work with a red LED? Does the '431 pull the voltage down low enough?Here's the LTspice simulation of a simple circuit using a TL431 programmable reference as a comparator to light an LED when the voltage is below the setpoint (2.5V as the Ref input) and turn it off above that point.