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Old 11-03-2019, 03:57 AM   #1
sam_sam_sam
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Default How to use a SCS not a SCR

I would to find a practical circuit on how to use a SCS device for a Capacitor discharging battery spot welder

Anyone have any idea on how to do this

I have done a Google search but have not really found anything I can use
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Last edited by sam_sam_sam; 11-03-2019 at 03:59 AM..
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Old 11-03-2019, 04:04 AM   #2
petehall347
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Default Re: How to use a SCS not a SCR

https://www.allaboutcircuits.com/tex...ed-switch-scs/
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Old 11-03-2019, 05:03 AM   #3
Curious.George
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Default Re: How to use a SCS not a SCR

Quote:
Originally Posted by sam_sam_sam View Post
I would to find a practical circuit on how to use a SCS device for a Capacitor discharging battery spot welder

Anyone have any idea on how to do this

I have done a Google search but have not really found anything I can use
An SCS is (effectively) just an SCR with all four layers bonded out -- instead of just the three for an SCR.

[You can also use a GTO or sensitive gate SCR -- though with considerably more hassle]

The problem you will have is deciding when to force the device off. The advantage of an SCR is the device shuts itself off when the current drops to zero -- hence ideal to use to dump a packet of stored charge into a load.

Otherwise, you will have to develop some criteria to determine when to gate the device off AND ensure your control circuit continues to "behave" while the load is being hammered (i.e., if you're having problems with an MCU surviving the firing, the MCU is equally likely to have "lost its mind" at the time you are expecting it to turn off the switch.)

A better solution is to determine how much charge you want to dump into the load and then control the orderly accumulation of that charge into a storage device (e.g., capacitor/inductor). Then, once you've accumulated enough charge, STOP accumulating any additional charge and, some time later (depends on how leaky your storage device is), fire an SCR to dump the charge into the load. The device that makes this firing decision need not continue to "behave" during the interval while the charge is being dumped into the load.

Expect the SCR to reset once the charge has dissipated. Then, let the entire circuit/process start anew.

Look for schemes of CDIs to get started.
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