Hi, ive been working on a power supply using scr control. But i need suggestion on how to fix the high current from the 220V to scr, im using 25A scr, and my target output is 12V. The trigger is fine but the the part with the scr bridge is not good. Any suggestion?

 

You have no resistors in series with the opto leds, U8 and U10 are wired to the negative supplies, they should pulse the gates positive to the Cathodes, your better using pulse transformers to fire the scrs, only need to fire opposite pairs every half cycle..


https://www.ibiblio.org/kuphaldt/electricCircuits/Semi/03221.png

 

You have no resistors in series with the opto leds, U8 and U10 are wired to the negative supplies, they should pulse the gates positive to the Cathodes, your better using pulse transformers to fire the scrs, only need to fire opposite pairs every half cycle..


https://www.ibiblio.org/kuphaldt/electricCircuits/Semi/03221.png

just wanna clarify, so i have to connect resistors at pin 1 of each of the opto leds? and "U8 and U10 are wired to the negative supplies" is not really clear to me. thanks tho

 

Yes put the resistors in series on pin 1 of the opto, the C/E transistor of the opto goes across the gate and anode to fire the scr,

but the two scrs that are supplying the Negative rail wont fire, they need to be pulsed positive with respect to the Cathodes, so you need pulse transformers.

 

Hello,

Did you read the User Agreement ?

It has these restricted subjects in it:

Restricted topics. The following topics are regularly raised however are considered "off-topic" at all times and will result in Your thread being closed without question:

• Any kind of over-unity devices and systems
• Devices designed to electrocute or shock another person
• LEDs to mains
• Phone jammers
• Rail guns and high-energy projectile devices
• Transformer-less power supplies

Your circuit is DIRECTLY connected to the mains and can NOT made safe.

Bertus