The thing is that the circuit was not functional—there were only places for the transistor, LED, and resistors on the board ... Of course, the LEDs might be separate as well. As for Q1, Q2: any ...

A transistor is a key component in electronics ... This makes it a latching device, ideal for alarm circuits. It will conduct a forward current (in the direction of the triangle – from the ...

You need devices with very low input thresholds to make these circuits operate at low voltages. Silicon bipolar transistors typically need around 600 mV at their input (V BE or base concerning emitter ...