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It is also worth noting that the temperature coefficient of a 4.7 V Zener diode is close to that of the emitter-base junction of a silicon transistor at around −2 mV/°C, so in a simple regulating circuit where the 4.7 V diode sets the voltage at the base of an NPN transistor (i.e. their coefficients are acting in parallel), the emitter will ...
Diode circuit implementing AND in active-high logic. Note: in analog implementation exact output currents will be different from +5V supply. This circuit mirrors the previous gate: the diodes are reversed so that each input connects to the cathode of a diode and all anodes are connected together to the output, which has a pull-up resistor.
In the Zener diode, the concept of PIV is not applicable. A Zener diode contains a heavily doped p–n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material, such that the reverse voltage is "clamped" to a known value (called the Zener voltage), and avalanche does not ...
Too large a capacitance (>0.1 μF for an 0D3, for instance), however, and the circuit will form a relaxation oscillator, definitely ruining the voltage regulation and possibly causing the tube to fail catastrophically. VR tubes can be operated in series for greater voltage ranges.
A digital clock made only with discrete transistors, diodes and resistors, no integrated circuits. This clock uses 550 switching diodes and 196 transistors to divide 60 Hz power-line frequency down to one pulse per second and provide a display of hours, minutes and seconds. The DTL propagation delay is relatively large. When the transistor goes ...
Here, the load current I R2 is supplied by the transistor whose base is now connected to the Zener diode. Thus the transistor's base current (I B) forms the load current for the Zener diode and is much smaller than the current through R 2. This regulator is classified as "series" because the regulating element, viz., the transistor, appears in ...
A Zener diode, when reverse biased (as shown in the circuit) has a constant voltage drop across it irrespective of the current flowing through it. Thus, as long as the Zener current (I Z) is above a certain level (called holding current), the voltage across the Zener diode (V Z) will be constant.
The first two of them are dual versions (series and parallel) of the general positive feedback system. In these configurations, the output voltage increases the effective difference input voltage of the comparator by "decreasing the threshold" or by "increasing the circuit input voltage"; the threshold and memory properties are incorporated in ...