Re: [CAD_CAM_EDM_DRO] Re: Spindle Relay Question

spc_aux wrote:

>--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
><dave_mucha@y...> wrote:
>
>
>>DPDT solid state relays are something I have never seen.
>>
>>
>
>Would an H-Bridge drive not be pretty close to a "DPDT solid state
>relay"?
>
>

Yes, they would wired exactly the same way. A DPDT relay has four
mechanical contacts where the h-bridge has 4 transistor 'contacts'.
Four of the SPST SS relays would serve the same purpose, but would
likely be less cost effective than discrete MOSFET devices. Mechanical
relays would also work just fine, and probably be reasonably cheap.

The h-bridge requires two input lines to control all the valid states.
If you only want to do forward or backward, and don't care about
stopping (which is presumably acceptable for this particular
application) you can do it with one input. You end up with one input
that controls direction and one that controls speed.

Dave