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overvoltage protection circuit problem!!!

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studystudystudy

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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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D7 is connected properly for over-voltage protection, but D8 is not correct and should be removed. For reverse voltage you need a add a regular power diode in reverse direction across the SCR.
 
D7 is connected properly for over-voltage protection, but D8 is not correct and should be removed. For reverse voltage you need a add a regular power diode in reverse direction across the SCR.

to crutschow, thanks for you reply and advice

you suggestion is to put a regular diode parallel with the thyristor?
 
you suggestion is to put a regular diode parallel with the thyristor?
Yes, reverse parallel. That will clamp any reverse voltage to one diode drop below ground. To minimize that voltage you could use a Schottky diode. The diode has to be large enough to carry whatever current the source can deliver under short circuit conditions.
 
I suggest to add a fast blowing fuse in case the power supply has no overcurrent protection.

Boncuk
 
to bychon, thanks for spending time to draw the schematic,

in your schematic, you using 1N4001 series with Schottky diode and resistor to regulate the voltage,
second part is use 1N4001 series with Schottky diode to prevent wrong polarity,
third part is adding the triac parallel with second part to prevent overvoltage happen?

isit what i said is correct? can you briefly tell me how is your schematic work. i am sorry, i not up to that level, i am still learning, anyway, you guys help and suggestion is really helpful for me, here a very thank you to mr bychon.

to crutschow

thanks again for helping me

can i straight away use Schottky diode parallel with thyristor?
 
I am not sure what your intent was in the beginning, but it looks like a protection circuit of both polarities. I started out forgetting that zener diodes conduct in both directions and gave you bad advice yesterday. And yes, those are zener diodes, not Shottky's.

Analysis: Any voltage less than 5V will pass safely and not be affected. When too much positive voltage arrives at the circuit, The 1n4001 on the left will allow it to go to the zender diode. The voltage being too much will pass through the zener diode and cause a voltage on the resistor. That voltage will trigger the triac and the top line will be shorted to ground until there is no more current to keep the triac conducting. At the same time, the second 1n4001 will not let a positive voltage get through to the second zener diode, so that part of the circuit does nothing.

When too much negative voltage arrives, it uses the second diode path to fire the triac and nothing happens in the first diode path.
 
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