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TI_Trey

Discrete Solid State Relay BP

6 posts in this topic

Hi 43oh!

 

It seemed like there was some interest in my solid state relay board, so I figured I'd post up the design files.  Because of liability reasons (being high voltage and what not) I can't produce this, but your welcome to get some boards made and solder them yourself.  Be warned, soldering the heat-sinks to the board is VERY DIFFICULT!  You'll need a board pre-heater, hot air, and some good flux.

 

B2wxAFPCIAAHVxS.jpg

 

Schematic:

triac_board.pdf

 

Design package (in EAGLE 6.5):

triac_board.zip

 

Cheers!

 

 

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A few questions:

1) Did you solder the heat sinks to the HOT side of your power? So this means three is live AC on them? :excl:

2) Would I use these with European plugs, this cold be a problem, because those are reversible; there is no guarantee that one pin is line and the other neutral.

3) What are those little squares for below the triacs? Are those to accommodate a different sized screw block?

4) It looks like the 39 ohm resistors short circuit the triac, how do you actually shut off the power to the screw terminal?

 

I admit, my knowledge of triacs is rusty at best, but please enlighten me.

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I can address #4:the 39ohm R and 0.01uF cap form a snubber and are needed to prevent damage to the triac. They do not pass enough current to worry about in mot cases, but very small loads may have an issue, similar to when a CFL is controlled by a lighted switch, and the bleedthrough causes it to flash on every few seconds when the switch is off.

 

 

On item 1: many components have electrically hot heatsink connections in some circumstances-- for example the heatsink tab for most BJT devices is connected to the collector, and on a linear amp may be 100V or more to ground, and not isolated electrically from the heatsink, as isolators are significant thermal resistance. They need to be protected from contact with screening, inside a case, etc. like any other electrically hot component.  In this case, item 2 can be significant, in that a keyed connector can be used to insure that the HS is on the neutral (grounded) leg, though this isn't real reliable as there are plenty of places to mess up the keying. Most reliable method, and method used if the item is to pass testing for any listing agency, is to insure that all hot parts can not be reached from outside.

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[...] item 2 can be significant, in that a keyed connector can be used to insure that the HS is on the neutral (grounded) leg, though this isn't real reliable as there are plenty of places to mess up the keying. Most reliable method, and method used if the item is to pass testing for any listing agency, is to insure that all hot parts can not be reached from outside.

Not only hot parts, but also neutral parts must be unreachable in such devices. As you note, one cannot rely on keying on US plugs (or south European plugs, probably a lot more too). In European plugs there is no keying at all:

Schuko_plug_and_socket.png

European plug with protective earth (on side prongs)

 

multi_outlets_european_type_plug_surge_p

An extension socket with both protective earth sockets and non-PE sockets. Also note the plug depicted is a pan-european hybrid plug; it fits both European and South European sockets.

 

Euro-Plug.jpg

A non-PE euro plug.

 

As in the US, non-PE plugs fit in PE sockets, but not the other way around.

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A few questions:

1) Did you solder the heat sinks to the HOT side of your power? So this means three is live AC on them? :excl:

2) Would I use these with European plugs, this cold be a problem, because those are reversible; there is no guarantee that one pin is line and the other neutral.

3) What are those little squares for below the triacs? Are those to accommodate a different sized screw block?

4) It looks like the 39 ohm resistors short circuit the triac, how do you actually shut off the power to the screw terminal?

 

I admit, my knowledge of triacs is rusty at best, but please enlighten me.

 

1) Yes, heatsinks are hot.  There was no easy way around this with surface mount triacs.

2) I don't have a good understanding of home wiring, but I haven't had any line/neutral issues.

3) Those are for spade terminals.  A lot of the wiring in a toaster oven uses those.  I've used this board to make reflow ovens in the past.

4) Ya I think those should be 390 as RobG said.  Each terminal is switched by the triac.

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