I am studying for my EE exam ,I understand the general working of the circuit but there is some details about it I have to know. this regulator supply 24 volt with puissance nominale 200watt. it consists of full bridge rectifier, power transistor T1 we control his pussance point by an error amplifier with gain 'k' ,transistor T2 amply current , we have also subtractor R1=3300 ohm and R2=1200 ohm. we assume that the minimum output voltage larger than Vout by 1 volt (ie 25 volt) I have to choose the Capacitos to achive a ratio of Triangular Oscillating about 30% around the average value of output voltage (Voltage drop on the transformer is about 5% from it's value when there is no load,and the diods Voltage drop is 0.6 volt).

how this circuit work? and what the voltage drop and the average voltage value and the power dissipation on the transistor T1

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  • \$\begingroup\$ At 24 volts, 200 watts is how many amps? At this current, and during 1/2 of an AC power cycle, what is the relationship between capacitor discharge time and capacitance (assuming constant current). For a sine wave, what is the peak voltage compared to the RMS voltage? So, for the discharge rate you found, what peak voltage is required? Compensating for diode drop, what then is the peak voltage out of the transformer? So what is the RMS transformer voltage? And, allowing for transformer efficiency, what then is the ratio of the secondary to primary? \$\endgroup\$ – WhatRoughBeast Dec 20 '14 at 18:23
  • \$\begingroup\$ i want calculate all the parameters of this circuit and plot all the curves of current and voltages of each part . note:i just have this details .. thanx \$\endgroup\$ – user119436 Dec 20 '14 at 18:55
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    \$\begingroup\$ Press "CTRL-M" and you'll be magically transported to a land where not only can you draw a schematic of your circuit, but you'll also be able to simulate it and it'll all be posted here, where a picture is surely worth at least a thousand words. \$\endgroup\$ – EM Fields Dec 21 '14 at 1:34
  • \$\begingroup\$ thanx but i solved it as i told WhatRoughBeast \$\endgroup\$ – user119436 Dec 21 '14 at 3:44
  • \$\begingroup\$ @user119436: Sorry, but I don't see your solution anywhere. Can you please show the power supply connections to the opamps and how the subtractor's + input is connected to the circuit? Also, if you'd add "@EM Fields" to your relevant comments I'll get pinged by the system and won't have to remember to keep coming back here, randomly, to see what's going on that affects me. Thanks, :-) \$\endgroup\$ – EM Fields Dec 21 '14 at 8:06

The error signal is conditioned (set to the right level for the biasing point of the transistor T2) through the two op-amps on the right hand side. You would agree that resistor "Re" would have a set voltage across it for 24v.

As the output voltage of the PSU increases, the output of the second op-amp would decrease proportionally causing the transistor T2 to sink less current. If transistor T2 sinks less current, the voltage across the resistor between the base and emitter of T1 would also drop causing T1 to conduct less current and drop more voltage.

The opposite would also be true for the output voltage of the circuit dropping.


Looks like if T1 opens a bit, then the two OpAmps and T2 would open it even more. (First OpAmp's output down, second OpAmp's output up, T2 - base up, current throu T2 up, T1 opens). Let me suggest you to reconnect the OpAmp's to invert the signal.


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