Rookie question here: If I don't need to change direction very quickly, why not make my H bridge with relays and control speed with an N channel mosfet on the ground side?
@@nicksauer6749 Mechanical contacts burn and arc when used with any real current. Relays are also expensive compared to solid-state replacements. I've seen relays used in many applications, and they do OK. That is my opinion only, your opinion is just as valid.
@@LewisLoflin Thanks again Lewis. I have a relatively high current application where the speed of changing direction isn't particularly important. I only anticipate switching the relays at times when the Mosfet is off and no current is flowing. I think that would minimize arcing and relay deterioration. Perhaps 'what is best' depends a lot on the specifics of the application? I'm not really trying to push forward an opinion, just want to discover any pitfalls in my approach.
You can combine low-side mosfets with power pnp transistors on the high side. Base of the left pnp connected to drain of the right mosfet and base of the right pnp to drain of left mosfet through resistors. Use zetex PNPs starting with ztx or fzt.
nice to see new video, thanks a lot!
More to come!
Rookie question here: If I don't need to change direction very quickly, why not make my H bridge with relays and control speed with an N channel mosfet on the ground side?
You can do that, but it is unreliable, and the speed is slow.
@@LewisLoflin Thanks, I understand it would be slow, but why unreliable?
@@nicksauer6749 Mechanical contacts burn and arc when used with any real current. Relays are also expensive compared to solid-state replacements. I've seen relays used in many applications, and they do OK. That is my opinion only, your opinion is just as valid.
@@LewisLoflin Thanks again Lewis. I have a relatively high current application where the speed of changing direction isn't particularly important. I only anticipate switching the relays at times when the Mosfet is off and no current is flowing. I think that would minimize arcing and relay deterioration. Perhaps 'what is best' depends a lot on the specifics of the application? I'm not really trying to push forward an opinion, just want to discover any pitfalls in my approach.
You can combine low-side mosfets with power pnp transistors on the high side. Base of the left pnp connected to drain of the right mosfet and base of the right pnp to drain of left mosfet through resistors. Use zetex PNPs starting with ztx or fzt.
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Thanks
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