UCD 25 watts to 1200 watts using 2 mosfets

[Dzony988]

I Understand now.. Can I use +12V for protection (NE555) from TIP41C, and for gnd use Ucc-. Then I conect pin 3 of NE555 directly to SD pin. I forgot that needed +12V ref to Ucc- not to GND

 

[Dzony988]

Because lower disipation of shunt resistor, I will use transistor instead of optocoupler. Now voltage drop is 0.7V
In simulator it works (schematic like Luka's)

Rsens = 0.7V / (Ucc/2Rload*2*sqrt2)

Rsens = 1.4Rload*sqrt2 / Ucc (1.4~sqrt2) =>

Rsens = sqrt2*Rload*sqrt2 / Ucc

finaly

Rsens = 2Rload/Ucc (=) Ohms

 

[CPX]

I made a mistake regarding my wire/inductor protection...using an inductor with a core with value>1uH is not recomanded because it will be too sensitive to noise...
Aditional residual filtering should be made elsewhere...thanks Pafi for clearing that up.....so a low inductance(<1uh) wound wire is recomanded..

Dzony988 use optocupler/level shifter for ir2110 sd pin and faster detection if you love your transistors..

 

[Dzony988]

With optovoupler I need 1.5V drop, cant 1V like I think. For 1.5V disipation at shunt resisot is to big, and with mpsa42 can be fast too (i think) because Luka use it in his amp. This is his protection

 

[CPX]

I said optocoupler for comunication with ir2110...
With optocoupler for the detector yes you will have 1.0-1.1 volt drop..if you decide to use my protection i thing you will get away with 400mv drop but i do not think you will have the pacience to sort resistors and obtain minimum error...

 

[Dzony988]

Ok, you think optocoupler instead of NE555?

 

[fireworks]

Because lower disipation of shunt resistor, I will use transistor instead of optocoupler. Now voltage drop is 0.7V
In simulator it works (schematic like Luka's)

Rsens = 0.7V / (Ucc/2Rload*2*sqrt2)

Rsens = 1.4Rload*sqrt2 / Ucc (1.4~sqrt2) =>

Rsens = sqrt2*Rload*sqrt2 / Ucc

finaly

Rsens = 2Rload/Ucc (=) Ohms

Dzony, what software did you use for schematic capture ?

 

[CPX]

Optocoupler after ne555..but that ne555 protection i think it is to slow...

 

[Dzony988]

I use LiveWire simulator. Its good only for simple curcuits. And when I whant to capture, zooming on screen and press CTRL+PRTSC. Then paste to paint and save like .png document

 

[savu]

use ltspice and tina

best of both worlds. my opinion

 

[Dzony988]

@CPX
something like this?

 

[CPX]

Connect directly to sd pin from ne555,optocoupler is not needed now since you referenced protection circuitry to negativ rail..it seems i skipped your schematic before this last one..i am sorry.

 

[Dzony988]

Hahaaha ok , regards

 

[Dzony988]

Do anyone have curcuit of input signal limiter but without optical elements. I try in simulator many of curcuit from google, but it doesnt work or has lot of distorsion.

something good what you used?

Reason why without opto elemets is because I dont like it and bigger rison is that I can only find photo resistor LDR07

Regards

 

[CPX]

You can use a led-photo resistor combination...
Have you simulated this? Fast Audio Peak Limiter (figure 2)

 

[NMOS]

Do anyone have curcuit of input signal limiter but without optical elements. I try in simulator many of curcuit from google, but it doesnt work or has lot of distorsion.

something good what you used?

Reason why without opto elemets is because I dont like it and bigger rison is that I can only find photo resistor LDR07

Regards

try this its from APEX should working very well

 

[Dzony988]

Thank you NMOS

I tryed in simulator, but it has lot of distorsion and mestakes...

 

[CPX]

Dzony988 you will have saome distorsions when limiting starts to work..that is inevitable..have you tried my schematic also?

 

[Dzony988]

where is your schematic?

NMOS schemtic start with distorzion on 300mV AC and go up to 8%. Maybe something can be fone with optocoupler

 

[CPX]

There is a link in my post...
With optocoupler you will have no distorsions up to trip point since no active elements are present in the signal path...