Power supply cap multiplier with electronic protection

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Here is my final schematic for +-45 to +-50V and cca 11A short circuit protection.
There is a loudspeaker protection from DC voltage also, in case the amplifier failure.
The current protection monitor the currents in both sides and if one side tripe the electronic fuse, other side will switch off too. Similarly the loudspeaker protection will work, if one side is triped the other side is triped too.
Current protection has a time delay from 20msec to 400msec depends of the current level.
Simulations attached show it from 12A to 14A.
Up to now there was no interest and comments here.
dado
 

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Looks really good. I am using superb simple, mosfet based, capacitance multiplier, and it really is profitable device for class A / AB amps. I used simple RCRCR combination for mosfet's gate, and that also adds feature similar to soft start.
Build it, and tell us, how does it work in real life circuit. :)
 
I don't think the overload and short circuit will be fast enough to protect the supply. Also, I doubt the pass transistors can handle 10 amps without overheating. I could be wrong; have you done a worst case thermal analysis? I don't see any voltage reference in the schematic. How do you think this will regulate if the input line voltage changes?
 
I don't think the overload and short circuit will be fast enough to protect the supply. Also, I doubt the pass transistors can handle 10 amps without overheating. I could be wrong; have you done a worst case thermal analysis? I don't see any voltage reference in the schematic. How do you think this will regulate if the input line voltage changes?

Here is simulation at cca 10 A of the load current. There is about 5 V of the voltage drop on the regulation transistor and with 10 A it gives 50 W. Look here for SOA http://www.onsemi.com/pub_link/Collateral/MJL4281A-D.PDF
This is not a stabilizator but regulator or some kind of a capacitor multiplier. It will follow slow input voltage changes, but regulate a fast ones.
dado
 

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dadod, just saw your thread linked from other one - late, as usual!

What does all the circuitry around Q6,7,8 &9 actually do, including the zeners D7,8,9 on the +ve rail (similar to -ve rail) - if this can be either simplifier/left off, it's a much simpler cct and I might try it out.

... james
 
dadod, just saw your thread linked from other one - late, as usual!

What does all the circuitry around Q6,7,8 &9 actually do, including the zeners D7,8,9 on the +ve rail (similar to -ve rail) - if this can be either simplifier/left off, it's a much simpler cct and I might try it out.

... james

Q7 and Q8 act as “thyristor” circuit, they are normally off, but if an input voltage is applied to Q8, even briefly, it will conduct and feed current into the base of Q7. This will make Q1 conduct, which in turn, will feed current into Q2, which holds the circuit on, or latched.
Q9 is the loudspeaker protection sensing element, and the zeners define that what difference in supply lines are acceptable, in this case if differente is more then 20 V it will trigger protection and cat the power. This will happen if one of the supplies is cut off, and it will then turn the other line off as well.
dado
 
Hi Damir,

This is a nice solution to a problem I have been trying to solve with my latest amplifier. Could do with higher voltage rails but I suspect this can be easily achieved.

Do you have a latest version or is the version in your TT amp thread the final solution?

Paul
 
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