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I want to have 220v dc using a mechanical system (without using diodes ,or with using homemade diodes) so I came up with this idea : when the wave is positive the electromagnet atract the bendable plastic up ,so it will tuch the blue and red , and when the wave is negative the electromagnet atract the bendable plastic down , so it will tuch the red and blue wires (so the polarity switches).

but the problem is the output form is not a line (output is not dc).

  1. where to add capacitor and what value to shift the output ?

  2. is there another way to get 220v dc using an ac motor (or any way) ?

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    \$\begingroup\$ Use a DC motor 'in reverse' as a generator, driven by an AC motor. The commutator in the DC motor will do the rectification job for you. \$\endgroup\$ – brhans Feb 5 at 18:52
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    \$\begingroup\$ also see: mercury rectifiers \$\endgroup\$ – Marcus Müller Feb 5 at 19:35
  • \$\begingroup\$ Adding capacitors without rectifier diodes will not help you. \$\endgroup\$ – Elliot Alderson Feb 5 at 19:38
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    \$\begingroup\$ If you managed to get this to work it will spark like hell and the contacts that switch the 220 V will burn out very quickly. The sparks generate a lot of radio interference (sparks was what was used before the electronics were invented to generate proper radio signals) and disturb all kinds of equipment. So really: Why do this? \$\endgroup\$ – Bimpelrekkie Feb 5 at 19:44
  • \$\begingroup\$ A few things. 1. The switching time for the contacts to open and close is not consistent. 2. The contacts bounce. These things combine to result in the contacts rapidly opening and closing when the voltage across them is not zero, which means arcing and reduced life. \$\endgroup\$ – uglyoldbob Feb 5 at 19:56
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What you're describing is a vibrator used as a synchronous rectifier. Before transistors were invented, automobile radios often contained vibrators to produce pulsating DC from a 6- or 12-volt car battery, changed to AC and stepped-up in a transformer and rectified by additional contacts on the vibrator.

It certainly did work, though inefficiently and with comparatively short life of the vibrator due to contact erosion. However, electronic synchronous rectifiers are commonly used in low-voltage supplies because of their high efficiency due to lower forward voltage drop than semiconducor diodes.

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