Sunday, 26 May 2013

Steampunk Electronics–LED Goggles Part II

The circuit for this project is pretty straight forward. Basically, each of the LED connect to the positive through the anode and to the negative via a 150 ohm resistor.

On a breadboard, it looks like this.


There is a jumper going from the positive to each LED anode. The cathode is connected to the negative through the resistor.

When it is powered up, it looks like this.


There are 20 LED in parallel.

This is enough LED for two eye pieces, making up a pair of goggles. I need to work out how long it takes before the LED drain the 9 volt battery. To do this, I’ve simply charged the 9 volt battery and marked the time when the LED were connected.

I did a rough test last night, but with 100 ohm resistors instead of 150 ohm. I started to get no light from some of the LED after 3 hours. That’s not a bad outcome. So long as I use rechargeable batteries, it shouldn’t be a problem.

I don’t know if the increase in resistance will make that much difference in the power consumption … but I guess that it will increase the glow time by about 33 – 50%. The power went on at 7:14pm today.

I don’t have any data on the LED power consumption.

Next image is at 8:30pm


Definitely less bright after 1 hour 15 minutes of operation.

9:30 and some of the LED are dark and overall, much less light output from the array.


I kept the LED array powered all night and there was still a very faint glow in the LED after almost 12 hours. Not enough light for anything practical and almost invisible … but still going. I would say that the acceptable level of light was after 1 hour 30 minutes of continuous running. So, this means that either I decrease the number of LED in the array or increase the number of batteries (2 x 9v for instance). The most practical approach would be reduce the number of LED to, say 6 LED per “lens” rather than 10. That works for me. So now the next task is to design and build the PCB for the lens.

That’s not going to happen very quickly at the moment, as we are moving house in 3 weeks and I have a shitload of stuff to pack.

Friday, 24 May 2013

Steampunk Electronics–LED Goggles

I’ve had an idea for embedding 12 LED into a ring structure that will fit into goggles.

The idea is fairly straight forward, 12 x LED, 12 x 100Ω resistors on a PCB ring with a power supply. I want to make the LED array into a single solid unit.

The LED will be arranged in parallel, that is, all of the anodes will be connected to the positive side of the battery and all of the cathodes will be connected to a 100Ω resistor and each of the 12 100Ω resistors will connect to the negative (ground) side of the battery. Also, the LED and resistors will be arranged around a PCB that has been cut into a ring shape.

12 LED Parallel Ring_pcb

The battery leads and  the resistors will be soldered onto the bottom of the PCB so that only the PCB and LED will be visible from the “top” of the board.

I will make a silicone mold that will embed the LED side of the project and this will be filled with a clear or slightly opaque resin. The other side of the project will be filled with a black resin (so that the light from the LED doesn’t come back into the eyes).

I’m going to need to make the PCB layout a bit more elegant and the LED equidistant so that it doesn’t look too crappy.

I want to make the LED ring sit inside of the ocular tube of the goggles so that they cast a bright light where the goggles are facing.

12 LED should drain a 9 volt battery fairly quickly, so I don’t expect that this will be a suitable torch, so I’m going with colour instead.

LED in resin

The battery leads will come out on the under side so that they can be attached to the inside of the goggles. I’m going to make a battery clip /pocket out of leather that will attach to the back of the goggles strap. But, first things first. Make the prototype, then make the molds, then see how the LED like being in resin.

The goggles will be another article much later. First I’ll be making the LED ring.

Paypal Donations

Donations to help me to keep up the lunacy are greatly appreciated, but NOT mandatory.