G+_Aye Mossum Posted June 30, 2015 Share Posted June 30, 2015 Here's what I'm working on. The further I get, the more discrete components I discover I need. For instance, I never knew I'd need an NPN and a flyback diode to drive the relays. Heck, I'd never even heard of a flyback diode before. (hint, this is going to be hooked up to 120V AC) Link to comment Share on other sites More sharing options...
G+_Eddie Foy Posted June 30, 2015 Share Posted June 30, 2015 Yup. You might be able to get a logic level MOSFET that has the flyback built in. (I remember seeing a fly back built into something) Link to comment Share on other sites More sharing options...
G+_Aye Mossum Posted June 30, 2015 Author Share Posted June 30, 2015 Actually, the Chinese ebay sellers are just going to keep getting a dollar at a time from me. Ordered 50 diodes for $1, 100 transistors for $1.50 (because the microcontroller can't source or sink enough milliamps to drive the relay coil) Link to comment Share on other sites More sharing options...
G+_Eddie Foy Posted July 1, 2015 Share Posted July 1, 2015 I'm in the same boat. Ordered the 100 diodes, PNPs, NPNs, and some other glue-logic. Its never a good idea to drive directly from a uController, especially inductive loads. Lately I'm in the frame of mind of through hole for prototyping on the breadboard. But surface mount for kitchen made PCBs (I rather not drill all those holes and snap all them bits :P) Link to comment Share on other sites More sharing options...
G+_Steve Prior Posted July 1, 2015 Share Posted July 1, 2015 Wouldn't solid state relays avoid the issue and be sufficiently cheap? Link to comment Share on other sites More sharing options...
G+_Eddie Foy Posted July 1, 2015 Share Posted July 1, 2015 SSRs usually are for AC loads. (which Aye Mossum is controlling) but yup. Don't forget the heat sink. SSRs are basically 2 triacs. I've had mixed results with SSRs Link to comment Share on other sites More sharing options...
G+_Aye Mossum Posted July 1, 2015 Author Share Posted July 1, 2015 All of the SSRs I find are driven by 5v signals. My uc runs on 3.3v. Could those still be triggered/powered by 3.3v or would I need to use a logic level converter, thereby just replacing the driving current and flyback issues with a logic level issue?? Link to comment Share on other sites More sharing options...
G+_Steve Prior Posted July 1, 2015 Share Posted July 1, 2015 Just an example (I haven't tried it): http://www.amazon.com/Amico-Solid-State-SSR-25-24-380V/dp/B0087ZTN08/ref=pd_sbs_328_1?ie=UTF8&refRID=1Z36FPRFHDTCJY88BKHW Link to comment Share on other sites More sharing options...
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