Capacitors take time to discharge through resistance, but they do not store enough energy to power a load.
A small amount of capacitor discharge current flowing through the base to emitter of a bipolar junction transistor translates into a lot of current flowing through the collector and emitter of the transistor. That current also flows though any load on the collector side of the circuit. At some point the capacitor will run out of current that it can provide and the transistor will turn off over a period of time.
- Brief circuit schematics with short video – List of pages
- Short learning basic electronic circuit tutorials for beginners
Become a Patron! Donations help a lot!
The 2N3904 is very popular NPN Bipolar Junction Transistor (BJT).
The pin layout and direction of voltage and conventional current flow (positive to negative) is shown in the first diagram.
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A lot of the components that I use are in this diode and transistor semiconductor kit.
- Brief PNP BJT timed fade off switch – 2N3906 bipolar junction transistor
- Brief NPN BJT current source controlled by trimpot voltage divider circuit
- Brief PNP BJT current source set by trimpot circuit – 2N3906 bipolar junction transistor
- Brief NPN BJT emitter follower set by trimpot using 2N3904 bipolar junction transistor
- Brief PNP BJT emitter follower common collector – 2N3906 bipolar junction transistor
- Brief 555 Schmitt trigger logic inverter
- Brief NTC thermistor voltage divider circuit
- Brief DPDT relay component introduction – Double pole double throw
- Quick NPN BJT switch circuit – Bipolar Junction Transistor
- Quick single switch controlled alternating flashing LEDs circuit
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