Need Help with a Slightly. Different LED Flasher Circuit - Novice Here!

Thread Starter

ninjagrips

Joined Nov 14, 2019
10
Dangit! A typo in my VERY FIRST thread title!!

Hey there, folks! So, I've been using the search function to find and read about different types of LED flasher circuits, and the closest thing I've found are the "Emergency Vehicle" flavor of flasher.

I need to figure out (if it's even POSSIBLE) how to build a circuit that will make 2 LEDS (one Red and one Green) blink, but not one right after the other. I'm gonna link a YouTube video to show Exactly what I'm trying to do, and hopefully that will make everything clear. The important part begins at 1:20


So, it looks to me like Mark Hamill is controlling all the "effects" in this short deleted scene from Return of the Jedi. He's got his little "space-compass-tweaker tool", and it looks like he flips a switch on that starts the green triangle LED flashing, and it flashes 7-8 times. Then he moves to the rear section inside the "control box" and it looks as if he touches a momentary switch or bridges a connection or something, which interrupts the green LED's flashing, and makes the red LED flash 5-7 times, then he "lets go" of that "switch", and the green LED starts flashing again, as he slides the circuit card closed, and "tests" the functionality of his newly constructed lightsaber.

I'm curious as to what the simplest way to achieve this would be. I've got VERY limited space inside the control box, around 47mm x 16mm, roughly, and about 10mm in height.

I'm hoping I can fit everything I'll need in there, along with a couple of small coin cells, like LR44 size.

I did build a 555 flasher on a spare bit of proto-board, and those components would definitely fit, and so would a transistor flasher. The thing is, that's not exactly what I need, I'm afraid. I'd REALLY like to get the LEDs to flash the way they do in the deleted scene. And I don't mind having it be "user"-operated, as it appears to be on the real hero prop, though it'd be pretty sweet if it were just automated after pressing or flipping a switch.

I've done a lot of soldering, and have experience installing electronics into replica lightsaber hilts and such, but I'm pretty clueless when it comes to actually designing or figuring out a circuit.

I'd really appreciate any help, suggestions, ideas or advice on this!!

Thanks everyone, for taking the time to read such a nerdy dilemma!!
 

SamR

Joined Mar 19, 2019
1,297
Welcome to AAC! First logically list what you want to happen and in the order to occur. Then we can talk about the hardware to accomplish the task. Then design the circuitry to make it happen.
 

Thread Starter

ninjagrips

Joined Nov 14, 2019
10
Well, I'd like to flip a switch, inside the control box, and have the green LED blink until another switch or button is pressed, at which point the red LED will begin to blink, and when pressed again, the red LED stops blinking and the green LED resumes its blinking. (or the red LED activation could be a press and hold momentary switch situation, too. Either way)

It'd be cool if there were a way to press yet another switch and have both LEDs just light up solid, in unison, but I'm not askin' for the world, here. Some flexibility would be cool, but I'll be satisfied if I can get it to behave the way it does in the deleted cave scene.

The other option, would be to press just one switch, have the LEDs go through the exact same cycle they do in the scene, and continue that cycle until the switch is pressed again.

Does that help?
 

Bernard

Joined Aug 7, 2008
5,286
Flashing LEDs are available & 2 could alternate with a single 555 or
maybe a 74HC132- 2 in Schmitt trigger NAND X 4, 2 stages as oscillators, fast & slow NANDed together driving one LED, Slow clk. inverted & NANDed driving other LED. It's late for me.
 

Thread Starter

ninjagrips

Joined Nov 14, 2019
10
I appreciate the suggestions, I'm not sure I'm seeing anything that will be self-contained and small enough for everything to fit in the box.

Is it possible to build two single LED flashers, and switch between them using a switch?

Simple and small is what I'm going for, and as little juice required as possible. No more than 3V.

The effects guys at ILM managed to build this in 1982, and had Mark Hamill control it "on the fly", so I know it's possible. I'm not positive the batteries are in the box, but I'm pretty sure everything else was.

My brain has turned to mush from trying to figure this out!
 

SamR

Joined Mar 19, 2019
1,297
OK, we have:
1. flip a switch (or button - )button probably better, momentary not held? Press again for stop? ON/OFF Green?
2. green LED blink
3. button 2 - ON/OFF Red When off start Green?
4. red LED blink,

So maybe
Button 1 - press to start green. press again to turn ALL OFF
Button 2 - press to stop green and start red, press again to stop red and start green

or simpler
Switch - ON/OFF when ON initiates green blink
Button - toggles Red/Green blink

So I see maybe blinking LEDs, no timer needed, Power ON/OFF and a button initiated flip/flop? (or a 2nd selector switch)

Adding timer would take more space but gives the ability to vary blink timing either fixed by capacitor/resistors or adjustable by potentiometer.

How much space is available in both internal and panel size?
 
Last edited:

Bernard

Joined Aug 7, 2008
5,286
Something to throw darts at: Back to post #4, MM74HC132 & 1 SMT 2N2222 or sim.. NPN , 2 mini SWs 2 batteries & LEDs will all fit in or on box. NO SW1 applies +3V to ckts. so U1 & U3 start oscillating, fast & slow. U3 turns on U2 when hi & U4 when lo. If SW2 is opened Red LED is off & Green is on solid- I hope. SMT LEDs are mounted on cover.
Might move SW2 over to circuit side. R3 = 10 k . R5, R6 to suit desired brightness, suggest 5mA to 10 mA.
I would go dead bug style wiring, SMT C s, choose values to suit.
 

Attachments

Last edited:

Thread Starter

ninjagrips

Joined Nov 14, 2019
10
Thanks y'all!

SamR, I like your "Simpler" idea, that's pretty much all I need! I suppose the only thing is the speed of the flashing. I'd need it to be as close as possible to the speed in the YouTube clip. I'm not sure any of the "blinky" LEDs I've seen will blink at that rate, but I've only seen a couple different kinds.

Bernard, I appreciate that you went as far as to draw a schematic! Most of what you're saying is Greek to me, but I can KINDA follow the drawing. I would DEFINITELY need to look up "MM74HC132 & 1 SMT 2N2222 ".

Tiny SMD stuff would be cool, but I'm not sure I could solder that. I'd certainly be willing to give it a shot, though.

Also, for everybody, I've actually already got the LEDs, they're triangular, and seem to be pretty rare. I had to file them down a little smaller, because they were a hair bigger than those found on the original prop.

I'll get some shots of the box for y'all, so you can see what I'm working with.

First, these are the pics I've got of the REAL prop. It's got what I'm guessing is a "cosmetic" circuit board on top, (or perhaps some of the components were actually part of the actual circuit?) with some suspicious looking red wires that disappear into a hole in the board (I'm thinking where the wires are soldered, could be where Mark triggered the red LED) then the LEDs poke through the holes in the thin aluminum plate, and enter the box UNDER the board, where I'm assuming the real circuit is, or perhaps small batteries (if not much power was required, or the small-enough batteries were common enough in '82).

I'm still not sure whether this effect was powered from OUTSIDE the hilt, or not. I've never seen any evidence of holes anywhere on the prop, other that the holes at either end, from the center drill, when this thing was machined on a manual lathe. Popular theory suggests that the hilt is solid, not bored out to accept electronics. This is still unproven.

Original Filming Prop...
Screen Shot 2019-05-03 at 2.09.03 PM.pngScreen Shot 2019-05-24 at 4.55.14 PM.pngScreen Shot 2019-05-24 at 4.24.53 PM.pngEF8BCBC7-6B6F-4B45-9ED7-2BB7C6D6C134.jpeg


Here's one of the two boxes I'm working with. The other one has a "fake" board in it, at the moment, and I could only attach so many pics, so, showing the empty box took precedence. I hope these help!!
1118190008b.jpg1118190009.jpg1118190011.jpg

The .487" in this next pic is the available depth I have to work with...

1118190011a.jpg1118190008.jpg
 
Last edited:

SamR

Joined Mar 19, 2019
1,297
OK it sure looks like it's going to have to be "dead bug" w/o a board. So you need to do some calculating for the resistor-capacitor combination to get the timing you want. Breadboard and test it to see if you are satisfied. Then dead bug solder it all together to fit within your box constraints and conformal coat it to insulate it. 5V Coin battery and holder may fit into the box or you may have to also dead-bug the battery connections. You might also consider resin encapsulation of all but the battery. As to switches these are what I normally use for breadboarding and are pretty small but you may find something better. https://www.aliexpress.com/item/32917522252.html?spm=a2g0s.8937460.0.0.48b82e0eQAfT1X
 

Wolframore

Joined Jan 21, 2019
1,321
this is how I would go about this... get a better picture of that circuit board in the prop photo, redesign it as a prop, it looks like a red jumper wire and blue cap on if. Then design a small micro circuit on the other side of your board, power it up using a lipo. So it has a on off which could be a simple switch or latching circuit. two Led output controlled by a switch or what ever you want. the micro is tiny and can be used for other effects if you think of more. I like Star Wars and special effects in general.
 

AnalogKid

Joined Aug 1, 2013
8,140
Is it possible to build two single LED flashers, and switch between them using a switch?
Yes.

But it is more simple (and smaller) to have one LED flasher, and switch its output to one of two LEDs with a toggle or rocker switch. The circuit area will be less, but the toggle switch might be larger than whatever you plan to use as the pushbutton switch.

And, it is a simple circuit addition (two small diodes) to add another switch that turns on both LEDs whether or not the flasher is running, like a lamp test switch.

ak
 
Last edited:

BobTPH

Joined Jun 5, 2013
2,048
The smallest way to do this would be using a surface mount 6 pin microcontroller. The only other parts needed would be one capacitor, the two LEDs and the two buttons. It would fit easily on a 1 cm square PCB.

But, a lot of knowledge is needed to get started.

Bob
 

djsfantasi

Joined Apr 11, 2010
5,693
Do you know how to code already? An ATTiny85 can be programmed with the Arduino IDE and you can either use another Arduino to wire up a programmer. Or buy a ready-built programmer from Sparkfun for under $20.

Then, a short program loaded on the 8 pin microprocessor will do whatever you want. Note, I’d add two current limiting resistors for the LEDs.
 

djsfantasi

Joined Apr 11, 2010
5,693
Or just one if the program prevents simultaneous currents. Size, size, size. For the lamp test mode, alternate between then quickly.

ak
Right, that’s true. And all’s well and good until some wise guy uploads a different sketch.

Really, technically speaking you are right. If the micro is soldered onto a PCB and cannot be re-programmed, I’d go for it.
 

Wolframore

Joined Jan 21, 2019
1,321
Right, that’s true. And all’s well and good until some wise guy uploads a different sketch.

Really, technically speaking you are right. If the micro is soldered onto a PCB and cannot be re-programmed, I’d go for it.
technically it's never over... there's always ISCP
 
Top