Monthly Archives: November 2014

LED lights – Auto off after 0-3 minutes – Update 1 of 2

I have a two year old and she likes to play inside one of the kitchen cabinets.  I would imagine that it gets dark in there when she closed the door, so I decided to puts some lights in there.  Being a 2 year old she likely to burn through some batteries so I though I could do a bit better than a simple on/off switch.

To be honest I have been wanting to do something with a 555 for a long time.  I picked one up from Radio Shack back in January 2003.  Now there is a need, so now is the time.

I basically used this article as a basis

I easily had all the parts so it was just a matter of assembly.

I will be using the 555 in the mono-stable mode circuit.


The only differences I made is that the control resistor shown here as a 10k ohms has been replaced with a 500k potentiometer/preset and the control capacitor shown here was replaced by a 330uF cap (since that’s the closest I had).  These values workout to a timeout of 0-181.5 seconds, right in the range that I was looking for.

In this case I also decided not to go all out and do a circuit diagram an etch a PCB.  This is a simple enough circuit I can just use some perfboard without the fuss.

Here is my result. 20141130_205152

It actually came out quite nice.  It has one button that starts the timer and turns on the 3 white LEDs.   The button does on nothing while the lights are on so in order to keep them on you have to hit the button every time they turn off.


LEDs stand off the board for max dissipation in a case I will make next.

LEDs stand off the board for max dissipation in a case I will make next.

Bottom side

Bottom side

Massive 330uF radial cap and an 805 10pF cap under it.

Massive 330uF radial cap and an 805 SMD 10pF cap under it.

This will be powered by a 9v battery which will hopefully last a while at 2min duty cycles.  I am not sure what the current draw is when idol (I may measure this later) but I think I will add an on off slider switch.

The next step is to make a case.  I have some ideas on what I want to do with the case but I do know that it is going to have to be rugged enough for a 2 year old to be pounding on it every 2 mins.  I was thinking that would be similar in design to the staples easy button but I will see how that pans out.

That’s all for now hopefully I can get the case done soon and I will post the second update to this post once it is done.

Fuse – Welding filament clamp for 3D printer

Back in July I back a project  This looked like a neat idea.  Basically it has a heater in the center of a Teflon block and a 1.75mm hole in it.  20140707025312-Slide_1

You put one end of filament in one side and another piece in the other push it through and it welds the two pieces together.

I received my Fuse today.  Here is what I got.

20141114_211810 20141114_211819 20141114_211901 20141114_211913Overall construction is good, no issues there.  It looks well machined and assembled.  Of coarse the next step it to plug it in an give it a try.

This is my first attempt.  It looks  pretty ugly.  The filament squished out into the slit around the 1.75mm channel.  I had the screws tightened by hand the best I could.  I did not try tightening them with pliers since I did not want to damage the thumb screws.




Needless to say its not idiot proof as it take some getting used to.  Eventually after some practice I did start to get some usable joins.  This is one of the better ones that I was able to do.

Same join as above compared to another one that is poor.  You can see that the white part is bulged out.  20141114_222733

Initial reaction based on 1 hr of use (yes I know that hardly makes me an expert).

The idea is solid;melt the ends and jam them together.  This is a bit more challenging to pull off than you might think.  To be fair I am using PLA which is probably the most difficult material to work with due to its low glass transition temperature.  I found that the melting was difficult at best to control.  PLA just loves to melt and deform as I learned from my experience with the   This does not mean that I don’t think it can work.  It does take some practice and lots of retries but with time I think that I can do much better.  Unfortunately, due to its difficulty of use (right out of the box with no experience) I don’t think that we will see  wade spread use of this product.

My next step will be to make some multicolored filament and do some printing with it.  I am somewhat concerned with how the printer will handle the transition, especially when the filament is not perfectly consistent in diameter.  From everything I know and read I dont think its going to be a big deal, assuming that there are not any bulges that make the filament jam in the hot-end.

More post on this topic to come.