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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.
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 ...
The snubber diode is wired in parallel with an inductive load (such as a relay coil or electric motor). The diode is installed so that it does not conduct under normal conditions. When the external driving current is interrupted, the inductor current flows instead through the diode.
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 ...
The simplest circuit for the voltage reference is a resistor potential divider connected between the voltage rails. This can be improved by replacing the lower resistor with a zener diode with a breakdown voltage equal to the required reference voltage.