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I have Chinese "no name" servo drives with following inputs for speed and torque mode: enter image description hereenter image description here

I have got a MESA 6I25 card and want to use LinuxCNC as a controller. I want to design a BOB (break out board) for these servos. Now there's a question how to steer this servo from the MESA card, for example by using PWM output and converting this PWM signal to voltage. There are existing -7.5V and +7.5V rails. Is it possible to use two logic-level N/P MOSFETs to achieve this?

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    \$\begingroup\$ What does the Chinese in "Chinese servo drives" have to do with the voltage? P.s. almost every electronic device in your home was made in china or asia. \$\endgroup\$
    – Tim Davis
    May 16, 2021 at 20:24
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    \$\begingroup\$ Heh, you are right, however in servo drive world, names like Mitsubishi, Siemens, Heidenhain means quality and often a high price. Those that I have are kind of "no name", much cheaper, have very sparse documentation and are kinda unusual, which means they could need some "special care" when interfacing, who knows. Maybe I shouldn't add they're Chinese but whatever :) \$\endgroup\$
    – PSz
    May 16, 2021 at 20:29
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    \$\begingroup\$ China is a giant market for servo drives, cheap stuff is widely available there. So it might mean something. Usually the drives are compatible with some standard controller or are a direct substitute for a Japanese drive. \$\endgroup\$
    – user76844
    May 16, 2021 at 21:05

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You can use an analog switch (like the DG419) to convert your PWM signal to +/-7.5V amplitude. Just connect one of the inputs of the analog switch to -7.5V, the other to +7.5V and use the PWM signal to toggle between them. Then you can smooth out the resulting +/-7.5V PWM signal with an RC filter and you're good.

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