Hi Guys,
Recently I constructed a circuit using a voltage comparator, relay, transistor, some diodes and resistors. The output of this circuit is a LED. By having a specific range of input, the voltage comparator will enable the LED to be lit. LED is lit thru' the energizing of the relay. Theorectically, all calculations made are correct and the circuit is properly soldered. However, the LED will not light up unless I TOUCH certain parts of the circuit (with my fingers or any metallic objects). What can probably cause such an occurance?
Thanks ywz