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| How to set reference for a sine wave with dc supply |
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| C:
here Nice an simple |
| anishkgt:
Thank you. That looks like it is driving the AC side of the transformer Which was not my initial question or did i misunderstand it. I was looking at the secondary side of the transformer. Secondly those SCR's would need a gate current in order for them to conduct. |
| C:
The SCR's shown and VOM are your existing ones, use your circuit. Think about what happens to transformer and secondary when you spot weld All kinds of nasty happens. R2 just reduces the line voltage to transformer to a lower value and restricts current. This gives the secondary side a source for contact sense. Feed back through transformer on contact closure will cause a voltage change on R2 you just have to adjust R2 value to your transformer. When you know how voltage across R2 changes you can adjust the voltage sense of opto-coupler voltage sense. |
| C:
As I understand it, You are wanting to replace a foot switch that triggers the spot weld. You are trying to --- Quote ---detect when the electrodes touch the Nickel plates for a weld. --- End quote --- But to create a good spot weld you also need to force the Nickel against something, a second Nickel plate or a battery terminal. So in-place of detecting contact, I think you want a force sensor or displacement sensor. The better spot welders have spring loaded contacts, so you could just detect the spring deflection to trigger the spot weld. This would guarantee that you had enough pressure for the spot weld and be much simpler also . |
| anishkgt:
--- Quote ---he SCR's shown and VOM are your existing ones, use your circuit. --- End quote --- The existing schematic has one of the SCRs inverted but yours has them parallel, was that an error or intentionally drawn. So based on my circuit shouldn't R2 be connected to the anodes of the SCRs as you have drawn it ? i checked the voltage at the LIVE and LIVE_OUT and it reads mains voltage of 240V but i read 33V at the primary of the transformer and zero volts at the secondary. The primary voltage of 33V was intentionally induced for the whole idea for sensing. --- Quote ---adjust the voltage sense of opto-coupler voltage sense --- End quote --- Sorry did not get what meant here. |
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