I would like to install a low fuel level warning light in my 65 Mustang using a transistor switching circuit connected to the existing fuel level gauge.
I believe the easiest method is to tap in a transistor (NPN) between the sending unit and the gauge. This is a 5vDC circuit, fuel gauge resistance of 15 ohms and the sending unit range of 5-85 ohms. I want to feed the transistor base with the variable voltage from the sending unit to trigger the transistor at about 60 ohms (~1volt) and use either 12v or 5v on the collector connected to an LED.
Im hung up how to size the resistors for the base, emitter and collector.
Any help, suggestions, alternative methods are appreciated.
I believe the easiest method is to tap in a transistor (NPN) between the sending unit and the gauge. This is a 5vDC circuit, fuel gauge resistance of 15 ohms and the sending unit range of 5-85 ohms. I want to feed the transistor base with the variable voltage from the sending unit to trigger the transistor at about 60 ohms (~1volt) and use either 12v or 5v on the collector connected to an LED.
Im hung up how to size the resistors for the base, emitter and collector.
Any help, suggestions, alternative methods are appreciated.