| Electronics > Beginners |
| Transistor Switching |
| (1/7) > >> |
| Oslaw:
Hello all, I was testing switching with a 2n2222 NPN transistor and every time I connect the base directly to data source( or set my potentiometer to zero), the LED on the collector side turns off or goes dull Please what might be wrong. |
| Zero999:
A schematic would help. The transistor must have a base resistor and the LED a current limiting resistor. |
| Oslaw:
This is the schematic I used. It switches well until I remove 1k resistor connected to the base, then the LED goes dim or dies. |
| hamster_nz:
What are you using as a power source? Without either a base resistor, or a current limiting resistor for the LED everything should burn out (that is unless you are using a current limited power supply). Do you want to: a) see a design that will work or b) to understand why the existing design doesn't work, allowing you to design something that will. |
| Oslaw:
Both. I did just that and still same result. I am using a 9v battery. Below are pictures of the potentiometer tuned to both ends. At level 0 Ohm LED is dull and at 10k Ohms bright(at any resistance level above 0 ). |
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