overvoltage protection circuit problem!!!

Thread Starter

studystudystudy

Joined May 21, 2010
34
an my overvoltage protection circuit connect in this way?

the voltage input, 'V in' go through the voltage regulator, which are Zener diode D7 series with Resistor R2 showing in the attachment. Zener diode D8 connect parallel with D7 and act as the protection or prevent of reverse polarity of voltage and current going through output.

to consider the overvoltage, i add the thyristor parallel with D8, can it be connected in this way?
 

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eblc1388

Joined Nov 28, 2008
1,542
Zener diode D8 connect parallel with D7 and act as the protection or prevent of reverse polarity of voltage and current going through output.
Your circuit will not work. :(

The addition of another zener D8 in parallel to the original D7 has reduced the tripping point of your circuit to only one volt or a little more.

Remember, a zener is simply a diode when used in reverse and permits current to flow to trigger the SCR.
 

Thread Starter

studystudystudy

Joined May 21, 2010
34
Your circuit will not work. :(

The addition of another zener D8 in parallel to the original D7 has reduced the tripping point of your circuit to only one volt or a little more.

Remember, a zener is simply a diode when used in reverse and permits current to flow to trigger the SCR.
to eblc1388

so i have to remove the zener diode D8, but what if i want additional function that can prevent wrong polarity voltage and current going through. i hope this additional function can grounded the wrong polarity
 

bertus

Joined Apr 5, 2008
22,270
Hello,

@ Bychon, why go to an other forum if you can post the schematic over here?

@ studystudystudy, you can make two (contra mounted) circuits without the D8.

Bertus
 

Thread Starter

studystudystudy

Joined May 21, 2010
34
Hello,

@ studystudystudy, you can make two (contra mounted) circuits without the D8.

Bertus
if my circuit without D8, then it will be a overvoltage protection circuit. this is what i found in the internet sample circuit. but i want additional function where i can ground the wrong polarity. so i decided to add the zener diode which is D8.

sorry, i dont understand what is make two (contra mounted) circuits, is it you mean to have only D7 series with resistor, and parallel with thyristor. then make the same thing twice?

thanks for you post reply, thank you very much
 

Thread Starter

studystudystudy

Joined May 21, 2010
34
Hello,

You can even simplify the circuit:



Bertus
thanks bertus,

sorry, my understanding is low, despite the value of the zener diode or triac,

is this simplify circuit can do following three function?
1. voltage regulation - regulate the voltage
2. wrong polarity protection - ground the wrong polarity
3. overvoltage protection - ground the overvoltage occur

i actually don't know how to interpret the simplify circuit you design, lol.
i have to do more work on it.

thanks again for bertus and bychon
you both really help me a lot.
 

Bychon

Joined Mar 12, 2010
469
This is not a voltage regulator. It is an over-voltage detector, but you must already know that because you said that in the title of this thread. It reacts to excessive voltages of either polarity by shorting them to ground. You can not regulate a voltage by shorting it out.
 

Thread Starter

studystudystudy

Joined May 21, 2010
34
to bychon

thanks for advice

i need voltage regulation function, reverse polarity, and overvoltage protection
function, i attach a file, can it be like that?

where D1 and R1 act as a regulator
 

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Bychon

Joined Mar 12, 2010
469
With a big effort, I can imagine how that might be a voltage regulator for small currents IF you throw R1 away. R1 stops D1 from doing its job.

It's more like this drawing.
 

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