Hello all,

I continued the schematic for my project, which a power supply unit, 24V 4A.

These are the stages i have designed:
Common Mode Emi filter ( i know its not needed, but i chose to do so in order to learn ) i took example from other designs and calculated the cutoff frequency.
Transformer + Bridge Rectifier, which gives at the collector of each transistor, unregulated 30V voltage.
the drivery circuit, made with the OP AMP , the output of the op amp, which i calculated it to be around 24.7V
then with the formula VO=VZ*(1+R1/R2), i calculated R1 and R2, having Vz= 5.6 V and VOUT = 24 V
I took example from other designs, and they usually put a RE , emitter resistor of low value, which i did in the schematic.

I know that overall the circuit has not a lot of protection, like no Tvs or so, but beside that, is the concept correct?

The way i designed and calculated the sizing is correct for each component?

Thanks all for the help ( consider that im a newbie yet.. )

 

The noise filters on the primary side are optional. What is not optional is a fuse which is not shown.

I don't know about the voltage regulation on the secondary side. I think that the op amp cannot supply enough drive to the pass transistors.

 

The noise filters on the primary side are optional. What is not optional is a fuse which is not shown.

I don't know about the voltage regulation on the secondary side. I think that the op amp cannot supply enough drive to the pass transistors.

I will add them no problem .

U mean the current that the op amp can supply to the transistor bases? ( i chose worst case scenario, so i took the lowest Beta value )

 

How much current does the op amp need to supply?

 

How much current does the op amp need to supply?

around 80mA, i think this op amp has max rated at 65mA

 

The noise filters on the primary side are optional. What is not optional is a fuse which is not shown.

I don't know about the voltage regulation on the secondary side. I think that the op amp cannot supply enough drive to the pass transistors.

U were right, its not sufficient, i have added a transistor before the 4 pass transistors, what do u think? i connected this correctly?

 

Power supply decoupling cap across U3.
Noise filter cap across D1.

It's ok to spread out the components to make the schematic a bit more readable. Electrons are cheap.

ak

 

Power supply decoupling cap across U3.
Noise filter cap across D1.

It's ok to spread out the components to make the schematic a bit more readable. Electrons are cheap.

ak

Hey,
Just a question, why D1 is a noise source?, its better to have a cap across D1 so voltage is more stable?

 

why D1 is a noise source? its better to have a cap across D1 so voltage is more stable?

A zener diode by itself cannot break into oscillation, one form of stability. A zener diode's reverse voltage does change with changes in temperature, another kind of stability.

Separate from that, reversed-biased diodes of just about any kind are known for being a noise source. Why? - Physics. That is why a reverse-biased transistor often is used as the core of white and pink noise generator circuits.

ak

 

A zener diode by itself cannot break into oscillation, one form of stability. A zener diode's reverse voltage does change with changes in temperature, another kind of stability.

Separate from that, reversed-biased diodes of just about any kind are known for being a noise source. Why? - Physics. That is why a reverse-biased transistor often is used as the core of white and pink noise generator circuits.

ak

Oh i understood, It would be useful if im building a noise generator circuit to leave It without a capacitor, but this isnt the case