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Forum Index : Electronics : Building a solid-state SPDT switch....
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
Hi. I need a solid-state SPDT switch to use as a relay replacement for switching power between the main PSU, and a battery backup. Switch has to work on DC and handle up to 5A. I have just been using a standard mechanical relay for this up until now, but thought I could probably get a quicker switch-over time if I could find a suitable solid-state switch. All the SSS's I have looked at are SPST, and most tend to be for switching AC only(although there are some DC ones). As I need DOUBLE-THROW changeover contacts, I was thinking along the lines of a modified H-bridge, using only the upper high-side switching, but I am not sure about that idea. Currently, the DIL relay flicks the supply over in 4mS, which is pretty good, and I use a 10,000uF reservoir cap on the output to sustain the load for that 4mS, and that does work for all but the heaviest of loads. However, solid-state would be preferable, probably cheaper then the relay using MOSFET technology, and would allow me to drop the reservoir cap value right back to 1000uF or so. Does anyone have any circuit ideas on the best way to do this? Smoke makes things work. When the smoke gets out, it stops! |
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| davef Guru  Joined: 14/05/2006 Location: New ZealandPosts: 499 |
The only device that I am aware of is a high-side MOSFET switch. I haven't seen any pre-built modules. You wouldn't need a very big MOSFET for 5A. try here |
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| larny Guru Joined: 31/10/2011 Location: AustraliaPosts: 346 |
Yes, but you would need 2 MOSFETs. Do you need any more assistance? |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
I have just used the relay as I have done before, but I am still interested in any ideas you may wish to post.  Smoke makes things work. When the smoke gets out, it stops! |
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