CuriousMarc Holo Lights
I developed these lights to replace other disappointingly dim and unfocused lights that had been offered before. They fit inside a standard holoprojector housing and are meant to work with the optical lens used in them (which are 1-1/2" Cabochons from TAP Plastics).
They plug right in the MarcDuino v1, v1.5 and v2, but can be hooked up to anything. In fact think of them as LED replacements: you can just plug them in any circuit instead of a traditional LED, regardless of voltages and ground in the original circuit. They can be powered by a completely different battery source than the circuit they are plugged in.
Here is a video of an early version of the lights:
Ordering pre-build Holo Lights
Fully assembled CuriousMarc Holo Lights are now continuously available from Glyn Harper through a Council Approved run. The thread for signing up is below.
And of course you can still build your own following the simple instructions below.
Connecting the HoloLights to the Marcduinos
This is the most common use of my Holo Lights.
Diagram for the MarcDuino v1 is here
Diagram for the v1.5 is here
Connecting for the v2.0 is in the v2 video here
Building your own CuriousMarc Holo Lights
Schematics are shown below. The input signal goes through an LTV-817 optoisolator stage, which is then followed by an N-MOS power mosfet. The whole circuit acts like a very sensitive, non-mechanical relay. This means the two inputs (input + and input -) are completely floating. They can go anywhere in a circuit where a low power LED would go. The power of the control circuit can be completely independent, and of a different voltage of the power that drives the Holo Lights. They don't even have to share a ground.
This has the interesting side effect that you can control the HoloLight with an Arduino output, with either positive or negative logic. Ground the Input - to the Arduino ground, and connect the Input + to an Arduino digital output pin, and the light is off with a zero output and on with a 1 output. Connect the Input + to + 5V and the Input - to an Arduino digital output pin, and the light is on with a 0 output and off with a 1 output.
The PCB is shown below. It is available from OSHPark: https://store.oshpark.com/collections/droid-parts/products/droid-hololights-v2-0
The list of components is shown below. There are two options for resistor R1, depending if you want to power the lights from 5V or from 12V. Remember, since it is optoisolated, you can power this board completely independently from your control board. If you want, you can of course use the same 5V supply as the one power your MarcDuino or whatever you use to control the lights, but you can just as well use an independent supply of a completely different voltage such as your unregulated 12V battery. The two power sources don't even need to share a ground.
Assembling the lights
The original instructions and more details are on this thread: http://astromech.net/forums/showthread.php?12532-CuriousMarc-Holo-Lights-Board
Solder the passives: the blue 0.22 uF capacitor, the 100k resistor (braun black yellow) below it, the 1k resistor (braun black red), and R1 on top. You should use the recommended 82 Ohms (gray red black) value for a 5V build with the supplied LED. R1 value can be changed to accomodate different LEDs and supply voltages. On this prototype build I had a 56 Ohm instead, which was WAY bright and a bit tough on the LED.
Solder the opto-isolator. Note the orientation: the dot marking pin 1 in on the upper left.
Solder the LED. Note the orientation: the flat side is to the right.
The reflector hole needs to be slightly enlarged, re-drill it carefully to 5mm so the LED fits.
Attach the re-drilled reflector with two drops of CA glue on the bottom tabs:
I just hot glue them on the base of the holo, with wire going through the base:
Testing the Holo Lights
The Hololights have 4 wires, and they all have to be connected for it to work. The IN +/- wires connect where the original LED would go, and the BAT +/- wires go to the battery source. To use outside of a LED circuit or simply test, just connect the two IN +/- wires to the BAT +/- and power it up. It should light up, very brightly.
Note that the brightness and good focus is due to the particular white LED choice. If you change it for something else (in particular a much cheaper LED), the result might be much dimmer.
Connecting the Hololights to other systems
You can connect the HoloLights to replace any LED in any circuit. They are opto-isolated, so the HoloLight supply can be a different voltage or a completely different supply than that of your original circuit. The supply ground don't even have to be connected. Simply connect the Batt+ and Batt- to the power supply used to power the Holo Light (which again can be the same as or different from that of your circuit). The signal leads (input + and input -) are connected to the LED you are replacing.
Here are two common examples for the older JEDI and the Teeces systems. Note that this assumes an older Teeces system controlled by your own sketch, not a MarcDuino sketch. For the Teeces with the CuriousMarc sketch controlled by a MarcDuino, the Holo Lights connect directly to the MarcDuino Slave, and not to the Teeces.