When i simulate my circuit (one in picture) it does not work and the LED does not turn on. I am using 2 NPN transistors, 2 switches and 3 1k resistors. The battery is 9v. Can someone help me find whats wrong with it?
Your circuit is a strange mix of upside-down-ness. Figure 1 shows a more-likely-to-work configuration.
Figure 1. The standard solution to this problem.
A few tips:
- Draw your schematics with positive rail on top and negative at the bottom. It will be easier to trace current flow from top to bottom.
- Draw inputs on the left and outputs on the right. (You did this.)
- Add a ground symbol somewhere. Even if not connected to the Earth it provides a reference for all measurements taken on the circuit.
The battery and diode polarity are opposite to what is required using NPN transistors. With an NPN transistor, the base and collector need to be +ve wrt the emitter for collector to emitter current to flow.
If you substitute PNP transistors, I think the circuit might work.