The half-wave configuration is not as efficient at rectification as the full-wave. The real choice lies between the two full-wave alternatives: bridge or full-wave with centre-tap. The bridge configuration rectifies the full secondary winding voltage. In contrast, the two-diode with centre-tapped transformer secondary only rectifies half the secondary voltage on each half-cycle.
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During conduction, the capacitor charges up to the peak value of the waveform (1.4 times the RMS value). On the opposite half-cycle, and from the diode's standpoint, the transformer winding reaching opposite peak value (1.4 times the RMS value) adds to the capacitor charge for a total of 2.8 times the RMS value.
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With the RMS voltage defined in this example as the voltage from one extremity of the secondary winding to the centre-tap, each diode is subjected to 2.8 times the RMS voltage, peak reverse voltage from half the transformer winding adds to the peak DC output as a reverse bias on the diode during non-conduction ( each diode serves as a half-wave rectifier ).
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The discussion relates to rectification, thus DC voltage output is the criteria. Imagine a 12 volts AC secondary with a centre tap. A bridge rectifier across the full secondary will obviously provide twice the voltage of a full-wave centre-tap rectifier where each diode draws from half the secondary. The bridge rectifier will also output slightly more DC voltage after filtering than a half-wave rectifier across the same full secondary.
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Key word: FULL-WAVE. The two half-cycles are put to contribution. The output goes from zero to peak and back 120 times per second. Half-wave would be 60 hertz.
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Key word: HALF-WAVE. One half-cycle only is put to contribution. The output goes from zero to peak and back 60 times per second. Full-wave would be 120 hertz.
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A voltage doubler returns a DC voltage approximately twice the supplied AC voltage. Through combinations of diodes and capacitors, both half-cycles are rectified and added together. Two ubiquitous configurations are respectively designated as "half-wave" doubler and "full-wave" doubler. The designation has more to do with the ripple frequency than how energy is transferred to the output. Ripple frequency in the "full-wave" doubler is twice the supply frequency. They can be implemented at normal line frequency or in switching power supplies.
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During conduction, the diode must support the average forward current. Under reverse bias, the diode must support the peak inverse voltage present across it.
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Parallel capacitors are used to bypass voltage spikes. Parallel resistors across each diode in a chain of diodes equalize reverse voltage.
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A full-wave rectifier puts both half-cycles to contribution: pulsating direct current with 120 zero-to-peak transitions per second is produced.
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Filter chokes are wired in series with the rectifier output. The choke must support the current drawn by the load. Its inductance influences the reduction in ripple.
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Regulation is the change in voltage from no-load to full-load. The first filter element determines the classification. Capacitor-input filters ensure high output voltage but poor regulation: voltage soars to the peak AC value under no load and drops under load. Capacitor-input leads to high peak rectifier current. Choke-input filters limit the soar in voltage through counter-EMF and by opposing capacitor charge current. Peak rectifier current is constrained but output voltage approximates the average value of the AC waveform. Half-wave circuits have the poorest regulation.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Regulation is the change in voltage from no-load to full-load. The first filter element determines the classification. Capacitor-input filters ensure high output voltage but poor regulation: voltage soars to the peak AC value under no load and drops under load. Capacitor-input leads to high peak rectifier current. Choke-input filters limit the soar in voltage through counter-EMF and by opposing capacitor charge current. Peak rectifier current is constrained but output voltage approximates the average value of the AC waveform. Half-wave circuits have the poorest regulation.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Regulation is the change in voltage from no-load to full-load. The first filter element determines the classification. Capacitor-input filters ensure high output voltage but poor regulation: voltage soars to the peak AC value under no load and drops under load. Capacitor-input leads to high peak rectifier current. Choke-input filters limit the soar in voltage through counter-EMF and by opposing capacitor charge current. Peak rectifier current is constrained but output voltage approximates the average value of the AC waveform. Half-wave circuits have the poorest regulation.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Regulation is the change in voltage from no-load to full-load. The first filter element determines the classification. Capacitor-input filters ensure high output voltage but poor regulation: voltage soars to the peak AC value under no load and drops under load. Capacitor-input leads to high peak rectifier current. Choke-input filters limit the soar in voltage through counter-EMF and by opposing capacitor charge current. Peak rectifier current is constrained but output voltage approximates the average value of the AC waveform. Half-wave circuits have the poorest regulation.
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Regulation is the change in voltage from no-load to full-load. By ensuring a certain minimum current draw on the supply, the bleeder prevents the capacitors from fully charging up to peak AC values when no external load is connected.
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Series resonance in the first choke and first capacitor across the rectifier may cause excessive rectifier peak current and abnormally high peak reverse voltages on the diodes.
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Series resonance in the first choke and first capacitor across the rectifier may cause excessive rectifier peak current and abnormally high peak reverse voltages on the diodes.
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Inductors oppose changes in current. If no current at all is drawn from a choke-input filter, the effect of the inductor vanishes: no more counter-EMF or opposition to peak capacitor charging current. Subsequent capacitors are allowed to fully charge to peak AC values. [ nine tenths the RMS: RMS is 0.707 times peak, average is 0.637 times peak, 0.637 is nine tenths of 0.707 ]
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In a 'linear' voltage regulator, a voltage higher than necessary is first produced; this voltage is brought down through a voltage dropping component. A regulator circuit (e.g., a Zener in a shunt configuration) may draw more or less current through a passive resistor to compensate for external changes. The dropping element, in a series configuration, may be a tube or transistor whose conduction may be varied. In a switching regulator, the incoming DC is switched on and off; the on time is varied so that the average DC output is maintained regardless of current draw.
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In a 'linear' voltage regulator, a voltage higher than necessary is first produced; this voltage is brought down through a voltage dropping component. A regulator circuit (e.g., a Zener in a shunt configuration) may draw more or less current through a passive resistor to compensate for external changes. The dropping element, in a series configuration, may be a tube or transistor whose conduction may be varied. In a switching regulator, the incoming DC is switched on and off; the on time is varied so that the average DC output is maintained regardless of current draw.
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Key word: EFFICIENT. A linear regulator with an active series dropping device (tube or transistor) wastes less energy as dropping resistance is adjusted to whatever current is drawn. A linear regulator with a passive dropping resistor and a control device in a shunt configuration (Zener, tube or transistor) is wasteful because a fixed amount of current is needed to maintain a given drop in voltage regardless of load current; the device draws less when load current increases and vice-versa. The shunt configuration may be needed if the unregulated source demands a constant load.
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Key words: CONSTANT LOAD. A linear regulator with an active series dropping device (tube or transistor) wastes less energy as dropping resistance is adjusted to whatever current is drawn. A linear regulator with a passive dropping resistor and a control device in a shunt configuration (Zener, tube or transistor) is wasteful because a fixed amount of current is needed to maintain a given drop in voltage regardless of load current; the device draws less when load current increases and vice-versa. The shunt configuration may be needed if the unregulated source demands a constant load.
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Key word: REMOTE. Voltage regulation relies on comparing the output voltage to a set reference and using the error to adjust conduction in the control element of the regulator. Sensing the voltage at the load rather than at the output terminals of the power supply compensates for losses all the way out to the load.
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A three-terminal regulator is a single integrated circuit comprising a voltage reference, a comparator, an error amplifier, sensing resistors and a pass transistor. Some include thermal shutdown, current foldback and over-voltage protection. The three terminals are: unregulated DC input, regulated DC output and ground. Specifications include: maximum output current, maximum output voltage, maximum input voltage and minimum input voltage (because a minimum voltage differential is needed to maintain regulation, the drop-out voltage).
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A three-terminal regulator is a single integrated circuit comprising a voltage reference, a comparator, an error amplifier, sensing resistors and a pass transistor. Some include thermal shutdown, current foldback and over-voltage protection. The three terminals are: unregulated DC input, regulated DC output and ground. Specifications include: maximum output current, maximum output voltage, maximum input voltage and minimum input voltage (because a minimum voltage differential is needed to maintain regulation, the drop-out voltage).
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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A three-terminal regulator is a single integrated circuit comprising a voltage reference, a comparator, an error amplifier, sensing resistors and a pass transistor. Some include thermal shutdown, current foldback and over-voltage protection. The three terminals are: unregulated DC input, regulated DC output and ground. Specifications include: maximum output current, maximum output voltage, maximum input voltage and minimum input voltage (because a minimum voltage differential is needed to maintain regulation, the drop-out voltage).
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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In a 'linear' voltage regulator, a voltage higher than necessary is first produced; this voltage is brought down through a voltage dropping component. A regulator circuit (e.g., a Zener in a shunt configuration) may draw more or less current through a passive resistor to compensate for external changes. The dropping element, in a series configuration, may be a tube or transistor whose conduction may be varied. In a switching regulator, the incoming DC is switched on and off; the on time is varied so that the average DC output is maintained regardless of current draw.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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A three-terminal regulator is a single integrated circuit comprising a voltage reference, a comparator, an error amplifier, sensing resistors and a pass transistor. Some include thermal shutdown, current foldback and over-voltage protection. The three terminals are: unregulated DC input, regulated DC output and ground. Specifications include: maximum output current, maximum output voltage, maximum input voltage and minimum input voltage (because a minimum voltage differential is needed to maintain regulation, the drop-out voltage).
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The pass transistor is the device acting as a variable resistor to drop the unregulated DC source down to the regulated output. Power is voltage times current: in this case, the difference in voltage from input to output times the current drawn by the load.
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A voltage regulator maintains a stable output by comparing a sample of the output voltage with a reference and adjusting conduction in the pass transistor accordingly. The corrective action is only accurate for the precise point where the measurement is taken. Because of losses, the load itself may find itself at a lower voltage: this is the reason for 'remote sensing' in certain applications.
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Per Ohm's Law, resistance is voltage divided by current. Output voltage and total current drawn describe the load placed on the power supply.
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Key words: LONG-TERM. Regulation is the change in voltage from no-load to full-load. Static regulation relates to the supply's performance in relation with long-term changes in load resistance or line variations (AC source). Dynamic regulation is required when the current draw varies as a Morse key is pressed (CW) or with each syllable (SSB) in a final amplifier. A large output capacitor, the last in the filter configuration, can improve dynamic regulation.
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Key words: SHORT-TERM. Regulation is the change in voltage from no-load to full-load. Static regulation relates to the supply's performance in relation with long-term changes in load resistance or line variations (AC source). Dynamic regulation is required when the current draw varies as a Morse key is pressed (CW) or with each syllable (SSB) in a final amplifier. A large output capacitor, the last in the filter configuration, can improve dynamic regulation.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Regulation is the change in voltage from no-load to full-load. Static regulation relates to the supply's performance in relation with long-term changes in load resistance or line variations (AC source). Dynamic regulation is required when the current draw varies as a Morse key is pressed (CW) or with each syllable (SSB) in a final amplifier. A large output capacitor, the last in the filter configuration, can improve dynamic regulation.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Regulation is the change in voltage from no-load to full-load. Static regulation relates to the supply's performance in relation with long-term changes in load resistance or line variations (AC source). Dynamic regulation is required when the current draw varies as a Morse key is pressed (CW) or with each syllable (SSB) in a final amplifier. A large output capacitor, the last in the filter configuration, can improve dynamic regulation.
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Remember your Basic Qualification? The Regulated Power Supply comprises: the input, the transformer, the rectifier, the filter, the regulator and the output.
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A fast reverse-biased diode between the output and input terminals prevents a large capacitor following the three-terminal regulator from discharging through the regulator if the input was ever short-circuited.
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