Npnelite2

175

03:29:35

NPN switched emergency light v2 FIXED..an example of using NPN transistors in an inverter config so that when the switch is opened the LEDs turn on instead of the usual way. The switch is supposed to represent a power outage and the DC supply would be a wall wart adapter plugged into the light. Some changes have been made to the circuit based on info from agentaero and some of my own - switch was moved to better simulate an outage,diode added so circuit now works properly,resistor values changed to reduce idle current when LEDs are off and finally a spdt switch added to provide 2 led power levels.

published 9 years ago

jamlynx

9 years ago

12vdc source is only used for switching so could be any 9-12vdc adapter that can supply at least 10ma..6vdc source is 4xAA batteries. Real emergency light would have like 8+ leds but space is limited in everycircuit.

agentaero

9 years ago

Nice. Given this is an emergency light and the backup source are AA batteries, you need to find a way to stop the 1.27mA being drawn from the batteries in non emergency mode.

jamlynx

9 years ago

Yes..I had changed the values a bit already to reduce idle current but it seems it needs some more.

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