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How? If the current is limited to 3A, then why does it make a difference?A "short" lasting more than 50millisecs will roast the anode .
With the resistor values shown, it should work from 0-3.5A. You can increase the current range by decreasing the 330K resistor.I thought the circuit you gave will be variable from 0-10 amps? You mean that the circuit can only output 50VDC @ 3amps?
Do you think you could show this circuit you have already designed?I have already designed the circuit and will stick with it instead of the SMPS.
The circuit would need another transistor to boost the output current in that case. Additionally, the 0.1 ohm resistor could be reduced to 0.01 ohms 3W for when you increase the current range. The output transistor isn't sufficient to handle the e.g. 600W that it will be dissipating (based on guessed 10V arc voltage) so yes you'll have to upgrade it (and heatsink it excessively). Using a linear current source is not really suitable IMO at these current levels (depends on spark voltage though).I will want to eventually use 15 amps. What value do I have to increase the resistor to, and which ones? Do I also have to replace the mosfets with a higher range?
Is this for an unregulated supply? If it's just a cap discharging, then there's no explicit current limit and the short circuit current (and therefore dissipated power) could be immense.Yes, the ON time arc through the dielectric does also munch away the anode eventually but not as bad as a dead short. It turns red hot and "poof".
... I ran a EDM as a job for 13 years, and have been building a sinker style pulse machine for home use.
Awesome!
Would you care to share any of the "trade secrets"? Especially nuts and bolts data like what volts/current to use vs electrode area, frequency/duty cycle, issues with electrodes and flushing etc?
I've been thinking of building a 3D motion sink machine with a thin copper electrode to be able to carve molds etc from hard metals, or carve jewellery out of hard exotic metals.
We tried that with the new CNC Charmilles sinkers the company bought, and its just not really feasible. The edge wear on the electrode causes so much problems with holding a consistent shape, and it is so s-l-o-o-o-w to cut. And these were new top of the line machines.
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It's much faster, if you can call EDM a fast machining option, to just have shaped electrodes.
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