Hey all, I am not sure this is the right place, but I figure it is worth a shot. I am working on a project with LEDs attaching to a 1/8in thick plastic rod. The circuit is on the micro scale (1mm LEDs, 0.016 in copper wire, L41 watch batteries, etc.), but I am having a trouble with the wires touching and short circuiting, making the LEDs flicker.

Is there some sort of "micro/mini" breaker or pass that can flip off during a short? Or some sort of method or circuit design that can help? It cant be bigger than 1/4 of an inch. I don't even know where to begin looking!

P.S. the circuit is a simple parallel circuit with 5 LEDs and a couple watch batteries.

Thanks!

-Zach

 

A surface-mount resettable fuse comes to mind, but the current needed to trip it would probably flatten the battery in next to no time .
If the wires are enamelled they can touch without shorting.
What total LED current are you drawing?

 

1/4" in which dimensions? Length? Width? Height?

Alec has the "proper" answer though.. Insulation on the wires

 

That is overly complicated approach. Use insulated wire so they will not short.

 

That is overly complicated approach. Use insulated wire so they will not short.

+1
26AWG magnet wire.
Max.

 

Krylon Clear spray paint.

 

Insulated wire. +1
Consider a poly fuze like these.

 

Thanks for all the feedback! Here is a curve ball for your consideration:

The wires have to be bare so that the LED can make electrical contact at any point along the rods 7 inch length. Think of sliding a "bead" onto the rod that is the LED and it will light up at any point, however, if any metal connects the two bare wires, it obviously shorts.

I am working on the current draw and heat consequences of the short now.

 

Maybe you can get the wires more mechanically stable. Some thoughts:

Cross drill the rod at each end and thread the wire through the holes pulling it tight so that it won't flop around.

Stretch the wire taut on your bench and paint one side with epoxy (J-B Quick would be excellent) Place the rod on the painted epoxied wire. Wait until the epoxy cures. Repeat for the other wire.

Mechanically secure insulated that enameled magnet wire to the rod, pulling it tight. Scrape the enamel to bare the conductor.

Consider music wire. Very stiff and less likely to move around.

As long as you have the epoxy out, stick down one of the SMT polyfuses for protection.

Have fun!

 

I use a lot of this..http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_22631_-1

 

Maybe you can get the wires more mechanically stable. Some thoughts:

Cross drill the rod at each end and thread the wire through the holes pulling it tight so that it won't flop around.

Stretch the wire taut on your bench and paint one side with epoxy (J-B Quick would be excellent) Place the rod on the painted epoxied wire. Wait until the epoxy cures. Repeat for the other wire.

Mechanically secure insulated that enameled magnet wire to the rod, pulling it tight. Scrape the enamel to bare the conductor.

Consider music wire. Very stiff and less likely to move around.

As long as you have the epoxy out, stick down one of the SMT polyfuses for protection.

Have fun!

Ill definitely look into this, it gives me some ideas. However, I am less concerned about the actual wires crossing and more concerned about a foreign object shorting or even a drop of water.

 

conformal coat it..
or hot glue
or teflon tube slipped over the exposed areas

 

I use a lot of this..http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_22631_-1

Same here. I started using this back when wire wrap ruled the world but I still prefer it when prototyping with SMD parts.

I obtained a bunch in 10 colors off EBay... but seems the guy's prices have gone to the absurd. Seems I'll have to re-buy full spools off the brick & mortar distributors.