This transistor is a low-cost device, widely available and sufficiently robust to be of use by experimenters and electronics hobbyists. The construction of the 2N3904 and 2N3906 in the 1960s represented a significant performance and cost improvement, with the plastic TO-92 case replacing metal cans.
Both types were registered by Motorola Semiconductor in the mid-1960s.ĭevice packaging and specifications It is complementary to the 2N3906 PNP transistor. It is designed for low current and power, medium voltage, and can operate at moderately high speeds. The 2N3904 is a common NPN bipolar junction transistor used for general-purpose low-power amplifying or switching applications.
Also used in devices such as Power banks, Stopwatches, Coffee makers, etc.A 2N3904 in a TO-92 package on a breadboard (lower left). They generally serve as a stabilizing protection scheme for surge-sensitive appliances such as UPS, Fridge, Air Conditioners & Deep Freezers. The time delay of this circuit can be increased or decreased by turning the values of the capacitors C1- C3 & by using a transistor with a variable switching time. Here, a 1N4007 diode protects the SPDT relay from shorts. Subsequently, the relay coil energizes & makes the SPDT switch, in order to power an AC or DC load. After this, the capacitor C3 discharges and triggers the transistor Q3. The Capacitor C2 discharges after a delay & triggers transistor Q2, charging capacitor C3 which introduces a further delay. this triggers the Q1 switch and charges capacitors C1 & C2. On pressing the pushbutton (S1) the transistor Q1 receives a control signal at its base through a 47K resistor. Generally speaking, this circuit is an enhanced version of a single transistor time delay circuit.
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