Re: Building your own SSRs

Author:   Ted Dodson  Date:   12-17-03 02:45 The basic stuff you need for building SSRs... OPTOCOUPLERS: There is a better option for the optocouplers than the moc3010. If you want random turn on (in case you ever want to do dimming) use moc3023 rather than moc3010. For zero crossing (no dimming but a little easier on bulbs) use moc3043 or moc3063. The moc3023 is rated at 400 volts rather than 250 like the moc3010. They are 29 cents at www.arrow.com. The same price as the 3010 and a much better part. TRIACS: The only place I've found any real deals on Triacs is once in a great while on eBay. The SC141D that Tony suggests would be fine. You can get a little bit cheaper by doing a description search on the word "triac" (on www.arrow.com). For example I found BTA06-400B (6amp 400volt) for .54, BTA08-600C (8amp 600volt)for .55. Just make sure you check the data sheets so you know what you are buying. You want the TO220 style with an isolated tab. The isolated tab is very important! If it is not isolated it will be live or hot whenever the gate voltage is applied which could cause problems. Disclaimer: I don't understand everything in the specs! There is some stuff about sensitivity which I presume has to do with how fast the triac fires. I don't think it's a big deal in our case here but maybe one of the actual "experts" around here like will offer a better explanation. RESISTORS: You will need about 3 resistors per SSR. The cheapest place I've found to buy them is from Circuit Specialists at www.web-tronics.com. They are $3.00 for 1000 resistors! (I realize that you won't need 1000 but why pay $2.00 for 100 when you can get 1000 for $3.00? There's is a minumum order of $20 but there's so much cool stuff on their site.) The size resistor you need for the input voltage will depend on the specifications of the optocoupler you use. The moc3023 opto is a 5ma device so you would need a 470 ohm resistor if you are using a 5 volt source. I calculate that by letting someone else (who knows a lot more about it than me) figure it out. Here are the appropriate values from a post by Dan Baldwin in another thread: For control 5v - 5ma opto I do: R = (5-1.3)/0.008 = 462 ( I use a 470 ohm resistor ) For control 5v - 10ma opto I do: R = (5-1.3)/0.013 = 284 ( I use a 330 ohm resistor ) For control 5v - 15ma opto I do: R = (5-1.3)/0.018 = 202 ( I use a 220 ohm resistor ) For the complete description see the thread at the link below. Pay attention to Dan's posts and ignore my posts! ;) http://computerchristmas.com/ForumBoard/read.php?f=4&i=706&t=702 There are a couple more resistors in a SSR circuit and the size depends on which schematic you follow. I like the schematics from an article on the teccor web site. It is a great article that tells more than you ever want to know about SSR circuits. I don't have the URL handy but I will try to post it soon. PROTOBOARD (something to build the circuit on): You have to build your SSRs on something. I ordered some stripboard part number PC-171 from www.rpelectronics.com. I just checked and they are on sale for 4.08. I think up to 16 SSR circuits could be built on 1 board. I have the plans for this in my head. I have some of the boards and when I get some made I'll try to post some pictures or make a how-to. TED

Topics	Author	Date
Building your own SSRs  new	Brian Hawkins	12-14-03 15:20
Re: Building your own SSRs  new	Tony Eberle	12-14-03 19:18
Re: Building your own SSRs  new	Brian Hawkins	12-14-03 19:25
Re: Building your own SSRs  new	John Pidliskey	12-15-03 09:24
Re: Building your own SSRs  new	Ted Dodson	12-17-03 02:45
Re: Building your own SSRs  new	Brian Hawkins	12-18-03 09:56
Re: Building your own SSRs  new	Frank Olinger	01-12-04 11:17
Re: Building your own SSRs  new	Tim Fischer	01-12-04 12:27

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