An interesting pipe dimmer project

[KrisBlueNZ]

The capacitance, 0.068 µF (microfarads), should match exactly. That value is also called 68 nF (nanofarads).

You can use a component rated at a higher voltage, as long as it's not too big.

 

[hellraizor]

Ok. Keep the .068 and the voltage can be whatever as long as it will fit on my board. Thanks!

 

[hellraizor]

Would a 100v capacitor be ok even though the original specs call for 250v? If I use a lower voltage will it cause the light to be not as bright or cause other issues?

 

[hellraizor]

Sorry to be such a pain but I want to make sure I have all the right stuff. This is my shopping list minus the capacitor:
Triac
http://pages.ebay.com/link/?nav=item.view&id=270935040369

Diac
http://pages.ebay.com/link/?nav=item.view&id=260824520573

Resistor
http://pages.ebay.com/link/?nav=item.view&id=370949099002

Potentiometer
http://pages.ebay.com/link/?nav=item.view&id=250816593344

Pcb board
http://pages.ebay.com/link/?nav=item.view&id=271271902455

Does it look alright?

 

[(*steve*)]

Would a 100v capacitor be ok even though the original specs call for 250v? If I use a lower voltage will it cause the light to be not as bright or cause other issues?

The general rule with capacitors is: "Use the voltage specified or a HIGHER temperature". If the circuit calls for a 250V device, use 250V, 400V, 630V, etc., but NOT 100V

Whilst I don't think these will get a high voltage across them in normal operation, it would be wise to stick to the recommendation.

If a lower voltage capacitor is chosen it could fail. In one failure mode the lamp would come on dimly and your potentiometer would start to cook.

The parts you have chosen look "probably OK". The matrix board is probably not the best thing for mains wiring, and the pot is going to be connected to the mains. If it fails your knob and/or the case could become live (an excellent reason for an earth connection).

 

[hellraizor]

Ok got it. How about these 630v capacitors? They seem like they are a good size for what I'm trying to do and far exceed the 250v recommended capacitor? Capacitor
http://pages.ebay.com/link/?nav=item.view&id=111120442429
What kind of board should I be looking for? Thanks a lot. I really do appreciate the help.

 

[KrisBlueNZ]

Yes, those capacitors look fine.

That diac is good but as I said in post #29 the circuit you are working from is designed to use a neon bulb, which has different characteristics. If you copy the component values from that circuit but use a diac instead of a neon, you'll probably find that you can't dim the bulb all the way down. That's why I suggested looking for a different design, or reusing the components from your board.

As for construction, it's such a simple circuit that I would just use "skeleton wiring" - start with the large parts, and just solder the smaller parts to them, using their own wires to support them. You can also use glue. This assumes that you'll be enclosing the whole thing in potting resin or similar. You can't have things moving around and touching each other!

BTW in post #17 I suggested "potting mix". I should have said "potting resin" as in post #5. Sorry for the confusion!

 

[hellraizor]

Ok cool. Sounds good. Steve said that the board I chose wasn't the best kind to be using. What kind should I be looking for?

 

[KrisBlueNZ]

My suggestion is to skeleton-wire it. In other words, no board. But see the caveats I listed in post #47.

 

[hellraizor]

Oh ok. Sorry, I misunderstood initially. Thanks!

 

[(*steve*)]

Something mid way between that board you were looking at and skeleton (or dead bug) wiring is to use matrix board that is just bare board with holes in it (i.e. no conductive things to solder to. It is simply used to make the construction rigid by passing leads of components through the board, but then you solder the component leads together (perhaps with additional wires) on the other side.

If you're at all uncomfortable about things touching that shouldn't, this may be a way to go.

Here is an example. Note that it's getting harder and harder to get matrix board without copper on it these days.

Some of the really cheap stuff has copper held so weakly to it (and no plated through holes) that you can easily remove the copper by twirling the tip of a drill bit (using your fingers) in each of the holes.

 

[hellraizor]

Based on my zero experience putting together a board, I feel that my comfort level is with skeleton or using a matrix board. I understand what goes to what now and I plan on ordering the matrix boards I previously posted so that I can try the skeleton way and matrix way. This way I can see what is most comfortable for me to work with and what I feel I can put together safely. You guys are an absolute wealth of knowledge and I honestly can't tell you how much I have learned just from this single thread. I really appreciate all of the help and suggestions.