Judge Dredd Lawgiver Mark II with working electronics

Working Lawgiver Props from the Judge Dredd Movie (S. Stallone version)

►Back in June 2008 or so, I was contacted by a member of the RPF (Replica Prop Forum) , Rob Cowley, and he wanted a sound & light fx board for a lawgiver prop he modeled. Since my blaster core board is pretty versatile, I decided to take the challenge to code a new firmware that will recreate the features of the voice controlled gun, and maybe more.
The main modifications I did in the code were to change the "range" (aka blast power) selection system of blaster core and I replaced it with a multiple ammo clip. As a matter of fact, the lawgiver has several kinds of bullets and we needed an individual count for each of them.
I used the LED control circuits initially wired to the energy bargraph of blaster core to light up the barrel LEDs. There are only 5 leds on the side of the barrel, so I used the first one as the little red triangle indicator above the grip, then the five next on the side of the barrel.
The firmware reproduces the scroll up fx of the barrel when you select a new ammo kind, scrolling time being mapped on the duration of the sound played at the same time : the syth voice of the gun "saying" what you've selected. Novastar, who's also the master of SoundFonts for my Crystal Focus Saber Core accepted to give his voice to the gun.
The barrel LEDs are still used to indicated the remaining ammo for each category of ammo clip. With Rob, we listed the various kinds of ammo we wanted to have in the prop and we ended with :

rapid fire
double whammy
flare
armour piercing
grenade

On my side, I also wanted to have the "intruder detection" mode for the gun : in the movie, if a non-judge person tries to use the gun, he dies by an electric shock generated by the gun. This mode is a special "ammo style" meaning that you can select it with the aux. button like the other ammo kinds. When in this mode, pressing the trigger starts making an electricity buzz loop with all leds shimmering and flickering (and you're supposed to fall down, dead :-D )

►Some videos of the firmware work in progress :

After a while, and when Rob obtained his LG parts for the run he handled over the RPF, I accepted to make a special kit for this electronic boards, so that customers could also have a working LG with electronics, light and sound.
Here's the build log and tutorial...
Note that the electronic board for the lawgiver shares 90 or 95% of blaster core for the wiring, so please refer to blaster core user's manual.

►Preping and priming the parts
While the original model seems to be really good, from what I've seen on Rob's videos, the cast parts I got were really poor quality. It looked good overall but I soon discovered that all the surface under was full of bubbles, sign the resin was poured much too fast after mixing. Also, most of my parts won't fit in a way or another, some were highly assymetric : the molds were not held enough and changed of shape when the resin was poured in.
This is not a prepping tutorial, I'm not really good at this, I just did my best to improve what I got. I had to stop somewhere I'm not really satisfied with the prop but I got tired of sanding bondo.

First, I tried to improve the gap between the 2 halves. For this I used car finish bondo and some PE or PP film that is not supposed to stick too much to the polyester bondo.

Then I prepared the top part for installing the sight. Since the contact surface is really small and not enough for gluing, I first drilled and threaded some holes so that A+B epoxy glue will get prisonner in the holes. The hole were drilled from the inside of the top part, thru it, ended in the sight and were threaded all along so that resin can get a grip.

Then I added 2 pilot holes in the bottom cap to insert later some nails, so that the 2 halves of the gun are held with but the rear screws but also from the front inserts. The little holes will be filled later with bondo.

Once I've synched the 2 halves, I started filing & sanding the bondo, trying to perfect the seam...

Then I machined the barrel inner sides to reduce the depth of the led windows, it looked better to me to have the red perpex closer to the outside of the barrel sides.

I then drilled and machined the aux button housing. First the pilot hole and the location where the aux. momentary switch will pop out. Then I reversed the part and machined inside. Remember that the flat trigger will move and slide there, so the switch has to be really deep from the inside of the part. I ended with a little groove to allow the wire to escape from the switch location to reach the electronic board.

For the lower grip, I wanted an elegant solution that allows me to access the electronic board, especially the SD card, without complex operations to disassemble the gun. My parts are really not fitting at all, I can't hold the gun with the grip staying in position. I've installed some plastic sheet on the sides of the gun to make it thicker (not displayed on the pics below), and then I milled 2 holes to glue some rare earth magnets on both parts, with of course matching polarity. The grip is then strongly held in position by the magnet and it's enough if you don't shock the gun.

►Electronic wiring
We will start by wiring the firing LED, a common anode (+) RGB superflux LED. Here's the pinout of the part.
First thing to do is soldering together the red and green anodes (-) together. Those will be triggered by the main flash driver of the board. The firmware has been modified compared to blaster core so that the normal flash (all ammo styles except the intruder detection) triggers actually the main circuit with red and green AND the aux circuit with the blue dye of the RGB LED. Hence, normal flash is white (R+G+B) while the intruder detection, with the aux circuit only, is blue.
Use one of your 100 ohm resistor to wire the 2 anodes you've soldered.

Then take the power xtender board. You don't need its + track since the LED is a common anode. To save space and allow the whole system to fit in the barrel hole, you can cut the unused PCB track. solder the blue anode to another 100 ohm resistor, the other resistor leg to the power xtender board.
Then wire a red wire to the common anode, a black wire to negative of the power xtender (-), and another color (orange here) for the control wire of the power xtender labeled AUX. It will be soldered on the AUX labeled pad of the main board. Our Red + Green + resistor section here received a blue wire and will be soldered on the main flash circuit of the main board.

►Trigger : The trigger was simply epoxied with A+B araldite glue

Preparing the wiring of the barrel side LEDs. Those have a common ground that will return to the board main negative (-). Each LED is going with a 56 ohm resistor. I'm wiring this side first cause all the parts will be glued here except the aux switch (weapon selection / reload) and the other side LED which will be on the second half.

The trigger is a momentary switch which has one pole returning to the battery negative. I'm using here a 7.4V, 900 mAh, 2 cell li-ion pack and a recharge port that will be located under the bottom cap. Since the electronic (-) is going to the board thru the handle, I've taken the opportunity to chain the ground thru the parts I met on the path. This will include also the rear side LEDs and the full auto switch. The positive from the battery is going directly to the board since the main power switch will be made with a kill key in the recharge port, like in my sabers.

Now the rear side LEDs are wired as well as the full auto switch. Refer to the manual for the detailed wiring, just note that the ground wiring continues to the Red LED negative, and the full auto switch center pin before continuing to the main board negative pad (-)

Now the switches and rear LEDs are wired as well as the 5 remaining barrel side LEDs. Note that the order between the soldering pads and the LEDs is inverted due to how I placed the board, the SD card pop out for an easy access. Hence the wires were guided withing the LED path before turning back to the board.
LEDs are glued on the perpex with clear hot glue. I've finally sticked to Rob's perpex, which is better diffusing the light.
Note that the LEDs I'm using here are different than the ones you got with the kit : I'm experimenting with new LEDs, possibly brighter. They have the same exact forward voltage, so I didn't change the resistor.

The other half of the gun : now attaching the aux. button. The black wire with go to the common ground of the board, while the blue one reaches the aux. oval pad (the one with a thru hole, not far from the trigger pad).

Wiring the second half of the barrel side LEDs. Note that the returning wires are soldered on the first half LED legs, *after* the resistor, since it was calculated to provide a current that will be then split in 2 for each half of the gun. The ground is also chained between the 2 half and reaches the negative (black) wire of the aux. switch.

Ok, mounting the speaker like this is not so elegant, but the angular reflections of the sound in this area amplify the sound. The front second barrel was drilled to let the sound come out of the gun.
For the firing RGB LED, I've made a little connector using tulipe IC holder : the barrel top part has to be inserted prior being able to connect the wires, but with the 2 halves of the gun already attached, so it was impossible to solder this way. The connector allows an easy workaround to this.

Done ! I gave a try to some weathering. I know I suck for the paint jobs but everyone is allowed to try.

►Video Review