DIY SSR (Solid State Relay) ??? Can I ???

Whats inside a Solid State Relay? I bought 4 off ebay but daum, there not cheap.

I want to use Logic Level TTL or 5v (From a Pic(axe) ) whatever you want to call it, to switch 110v ac mains power to lights, like in a Christmas light show.

Suggestions?
Thanks-
Andrew

Well, I did find this info-
Solid state relay - Wikipedia, the free encyclopedia

Feedback on the data from there?

Id be interested to know WHICH MOSFET and OptoIsolator I would want to use to build my own please.

I figure no more than 100w of 110vac power across the "relay legs".

Thanks so much!
Andrew

RogerTango said:

Well, I did find this info-
Solid state relay - Wikipedia, the free encyclopedia

Feedback on the data from there?

Id be interested to know WHICH MOSFET and OptoIsolator I would want to use to build my own please.

I figure no more than 100w of 110vac power across the "relay legs".

Thanks so much!
Andrew

Click to expand...

Well a AC solid state relay is a opto-isolator driving a triac device. Attached is a typical schematic of what is involved at the internal component level. Note sure if you could build one cheaper.

https://www.electro-tech-online.com/custompdfs/2008/12/lowssr2.pdf

Your best best is to keep checking E-bay for surplus bargains and pounce when you see a good deal, even if you don't have an immediate need. The larger ones (the 2" square ones) are pricey because they are rated to handle up to 20 or more amps circuits on their outputs which is a lot of current to switch on and off. What the manufactures don't always make real clear is that those square one require quite a large heat sink to actually be able to handle their maximum rated current.

Lefty

Relays are easy to get and cheap. SSR's can be costly and need heatsinks.

There are lots of choices for 1-2A solid state relays. They are made by Toshiba, Crydom, etc. and are sold for $4 and up at distributors like Digikey and Mouser. They are PC board mount and don't have handy screw terminals, which might be a pain. Use the Part Search to find them. News: I just noticed All Electronics has one! CAT# SRLY-19 is a 1A solid state relay for US$3.25. There are others, such as SRLY-20 which is a pricey $6.50 for 3A.

Don't let the David Johnson PhD circuit scare you! His circuit is special because it needs only 50 microamps. Ordinary SSRs use about 10 mA and replace everything to the right of Q1 with just an MOC3020 (6 pin DIP) or a close relative. But it's still no fun building a solid state relay when you know how to get one in your price range.

Another option: If you aren't dimming anything, have you considered small relays?

Thanks all, I too have found that All Electronics has the 1a SSR for about USD $4, thats cheap enough to buy a dozen or so for the stock shelf!

I think for the effort needed, and the cost of all the parts, it would just be cheaper and easier to get the ones that All has.

But, I did at least learn something about SSRs!!

Thanks for the info everyone,
Andrew

Hi, all...first post.

Since you are planning a computerized Christmas display, I suggest you go to Do It Yourself Christmas and check out their SSR's. They are specifically designed to do just that. While there, you can look at some of the other boards, that make implementation easy.

Here's a link to what I think is one of the BEST Christmas light displays. Check out the videos, with sound on...

**broken link removed**

I am currently building two DIO96 boards, for 192 channels. I have about 70 relays I've bought off ebay, and I'm going to be building the rest. I'm even thinking about another 96 board, for 288 channels...I like lights!!

Good luck, it's great when you get it done!!

Roger

**broken link removed**