Lightsabre Sound and Light fx.

Well after some deliberation I have decided to start experimenting with my Raspberry Pi Zer0 first and see how close I can get to what I want to achieve, If this doesn't work out how I hope I will revisit some of the other ideas or simply take the easy route and buy a soundfx board from Adafruit.

I intend to use a Pimoroni Phat-DAC to output the sound effects but I haven't decided if I will use a mono or stereo amp yet, although I don't really think it will make much of a difference, other than a slight difference in my total spend at the end.

For the blade I've ordered a 2m 5.0vdc RGB LED strip which will be connected to 3 TO220 Mosfets so I can control the colours with the RPi0 and hopefully have several pre-defined modes with matching sound effects but that all depends on how I get on with the programming side of things later in the project, I will also use 1 or 2 super bright white LED's close to the base of the blade that will illuminate upon impact to create the flash on clash effect.

I'm hoping to use a Vibration sensor switch to trigger the flash on clash effect and the impact soundfx, and have found some cheap boards on ebay that look and sound perfect for this task, but I also have to consider a sensor to detect the Lightsabre being swung and initiate swooshing sounds, i Thought about using an Accelerometer for this but think that might be a waste as it only needs to trigger the effect not actually log the x,y,z points, which led me to consider another vibration sensor switch with softer spring, but with that I have to somehow differentiate between a swing of the blade or blades colliding and I don't see a way of not setting of the swoosh sound at the same time as the impact sound, unless there's a way to make the program override the swoosh when impact is sensed, guess I will have to investigate that further.

The hardest part of this for me at the moment is powering everything that is needed, I have a 5.0vdc 2600mah PowerBank which will power the RPi0, what I'm wondering though is would I be able to use a buck booster connected to the 3.3v pin of the RPi0 to boost the power to 5v for the Leds and other bits or would i be best looking at an alternative.

If anyone has any suggestions as to which mosfets, vibration and movement sensors would be suitable or what the best way for me to power it all is any guidance will be greatly appreciated and help me greatly, because at the moment I'm just guessing really and hoping I'm heading the right way with it.

Thanks,

Mark.

Well after some deliberation I have decided to start experimenting with my Raspberry Pi Zer0 first and see how close I can get to what I want to achieve, If this doesn't work out how I hope I will revisit some of the other ideas or simply take the easy route and buy a soundfx board from Adafruit.

I intend to use a Pimoroni Phat-DAC to output the sound effects but I haven't decided if I will use a mono or stereo amp yet, although I don't really think it will make much of a difference, other than a slight difference in my total spend at the end.

For the blade I've ordered a 2m 5.0vdc RGB LED strip which will be connected to 3 TO220 Mosfets so I can control the colours with the RPi0 and hopefully have several pre-defined modes with matching sound effects but that all depends on how I get on with the programming side of things later in the project, I will also use 1 or 2 super bright white LED's close to the base of the blade that will illuminate upon impact to create the flash on clash effect.

I'm hoping to use a Vibration sensor switch to trigger the flash on clash effect and the impact soundfx, and have found some cheap boards on ebay that look and sound perfect for this task, but I also have to consider a sensor to detect the Lightsabre being swung and initiate swooshing sounds, i Thought about using an Accelerometer for this but think that might be a waste as it only needs to trigger the effect not actually log the x,y,z points, which led me to consider another vibration sensor switch with softer spring, but with that I have to somehow differentiate between a swing of the blade or blades colliding and I don't see a way of not setting of the swoosh sound at the same time as the impact sound, unless there's a way to make the program override the swoosh when impact is sensed, guess I will have to investigate that further.

The hardest part of this for me at the moment is powering everything that is needed, I have a 5.0vdc 2600mah PowerBank which will power the RPi0, what I'm wondering though is would I be able to use a buck booster connected to the 3.3v pin of the RPi0 to boost the power to 5v for the Leds and other bits or would i be best looking at an alternative.

If anyone has any suggestions as to which mosfets, vibration and movement sensors would be suitable or what the best way for me to power it all is any guidance will be greatly appreciated and help me greatly, because at the moment I'm just guessing really and hoping I'm heading the right way with it.

Thanks,

Mark.

Hi Mark,

Your PowerBank could power the RPI and the LEDs I think? Worth a try. The 3.3V pin won't have enough power, there is only a finite amount of current that can be drawn from it, the exact value would be a guess since there are no schematics for the 'pi.

If you're open to eventually creating your own PCB (with say EAGLE or KiCAD) then you might want to consider this very interesting TPS27081A power load switchTPS27081A power load switch. I've not used it, but I plan to do so. It is small but still hand-solderable. It seems perfect for where you want to switch a couple of amps at 5V, and can be directly controlled from the 3.3V logic levels from the 'pi. And it is cheap. Without a PCB, you'd need some adapter board though for a prototype, like the one below. Ideally you need a 1mm or 2mm sized soldering iron tip although bigger tip is still usable, it really isn't a super-tiny SMD part. If you need help with this, let me know - noticed you're in the UK, I'm not so close to your town but could solder it up if needed to a board. But worth trying it yourself if you can, because this is not an overly small part so definitely achievable with most soldering irons.

Hey, I have a bunch of those boards on my desk

Mike

And Shabaz is right, they're not that hard to solder up.

Mike

They're great, aren't they! Love that you can get discretes, op-amps,  even logic gates in SOT-23.. it is like the TO-92 replacement for the 21st century..

Thanks for the quick response Shabaz, I will be trying the Pi and Led strip from the power bank as soon as they arrive, like you say its worth a try. I did forget to mention above that from the information I've found on the Phat-DAC it only uses 3 of the gpio pins but the amp would need a power supply. I feel quite comfortable with a soldering iron and I believe I have both a 1mm and 2mm tip on different Irons, So if I have to that would not phase me at all, and that chip is perfect, but I really do appreciate your offer and if things don't go so well I might yet take you up on it. I wouldn't know where to start trying to design my own circuits yet I've a lot to learn, I did try a few years ago in the hope of etching my own but that was as far as that went. So purchasing a few of the boards and power load switches might be a good idea.

It looks like the vibration sensor board I was considering will need power too, I need at least an hour of play before charge.

Could this be simplified by just using individual tilt and vibration sensor switches connected to thee gpio pins and trigger the effects or would I need to include anything else like resistors to protect the Pi?.

Mark. 

– I'd definitely go with an accelerometer instead of a vibration sensor, as it is very simple to generate an authentic and variable swoosh sound from g-meter data and at the same time detect and discern impacts, as these are a magnitude bigger than when the saber is swung. I'd accumulate the g-foces of all axes, to have acceleration of the saber as well as centripetal forces (more important) aboard. Then feed it to a static-noise generator to alter the wavelength – or play a clash sound, if g-forces are over a certain threshold. This sound effect compares somewhat to swing a tube faster or slower.

Mike

Hi Mark,

I had a look at the phat-dac thing, but they've not included an amplifier which is a shame, it would have taken hardly any space or cost for them.

The usual LM386 could be used, it is a fairly typical amp, and would have more than enough output for a speaker, and can run from 5V.

Another audio amp option is here BBB - Building a DAC - part 2 there is a circuit for an audio amp there which uses the   which operates at 5V too But the  LM4861MLM4861M

is only offered in an 8-pin SOIC package (again this is quite large so easy to solder on a PCB).

Anyway whichever amp you use, the stereo from the DAC can be summed into a single input using a couple of resistors (e.g. use anything of a few kohm, like 4.7k resistors).

Regarding the vibration sensor, you could have it a bit more advanced and use a combined accel/gyro module. Admittedly a bit over-the-top, but it gives you some flexibility when it comes to the

sound effects. For example some foreboding effects when the sabre is gently picked up or moved, and different effects when swung.

The DAC doesn't use the I2C pins, so you could connect some combined accel/gyro module which uses I2C as an example. I've used the MPU-9150, that's not a bad module - it would be a very advanced

sabre with that : ). The IC is now end-of-sale but it is still available all over the place on ebay, pre-soldered onto a small stamp-sized PCB (space matters for your application!) so easy-to-use.

The gyro will give XYZ rotation values that will increase in magnitude depending on how rapidly the sabre is swung, and you also have the XYZ accel values which will tell you easily if the

sabre is at rest (and in what orientation) or being held upright, etc, or moving.

If you play with both sets of values I'm sure you'll figure out some nice sound effects to go with the action.

To use the MPU-9150 boards, most of them accept a 5V supply (they have an on-board regulator down to 3,3V), so could be connected directly to the RPI 5V connection on the 40-way header

(the MPU-9150 doesn't consume a lot of current). Then just wire the I2C SDA/SCL pins to the RPI, and also a couple of resistors (e.g. 4.7k) from those pins to the +3.3V pin on the RPI, to build your

I2C bus.

How about using one of those little 2W class D boards off the net that seem to be about for like 99p. That way you have little to go wrong and enough power to make a reasonable noise!

Thanks for the pointers guy's I decided to go with a 2ch 3w digital power pam8403 class d audio amplifier board and the GY521 6 dof mpu-6050 3 axis accelerometer and gyroscope module for aduino but made the mistake of not checking whether the libraries for the acc/gyro were available for the RPi before ordering So I might need to re-evaluate this and follow your guidance and get the one you recommended above shabaz, if I cant get it to work. Only thing left to get now electronically speaking is the Phat-Dac and some resistors and i can start work on it.

Thank you all for your invaluable input and I will be sure to keep you informed of my progress and probably have a few more questions to ask along the way.

Mark.

Hi Mark,

The pre-built audio amplifier board seems a good idea!

You should be fine with the  MPU-6050MPU-6050 the MPU-9150 is a dual-die IC internally one die containing what is most likely an MPU-6050(or a close variant anyway and the other containing a magnetometer IC So the code is similar or identical

I've not tried the MPU-9150 or 6050 with the RPI(I used a-9150 with a microcontroller but I'm sure we can troubleshoot and get it working if existing RPI code on the Internet for the  MPU-6050MPU-6050 doesn't work The MPU-xxxx doesn't need anything uncommon like I2C'repeated starts etc and is therefore easy to work with

Do post a link to the 6050 or a detailed photo of it, just so it can be double-checked that it has an on-board regulator (otherwise it will need powering from 3.3V and not 5V) when you get a chance.