Positron Prototypes!

Fresh off the presses from Macrofab, the prototypes for my Positron Proton Pack Kit arrived this weekend!

IMG_3211 IMG_3225 IMG_3239 IMG_3247 IMG_3268 IMG_3276 IMG_3285 IMG_3292 IMG_3308 IMG_3315 IMG_3338 IMG_3364 IMG_3369 IMG_3405 IMG_3420 IMG_3426 IMG_3439 IMG_3471 IMG_3529 IMG_3538

Video of it in action will be forthcoming, just as soon as I can port all the code from the original kit over to it.   A short video demoing the bargraph and sound should be soon-ish as I’ve already ported that code, but the rest will probably take a couple weeks.

“What speakers do you recommend?”

I often get asked:

“What speakers do you recommend for your Proton Pack kit?”

For my kits,  I recommend one or two 4 ohm car speakers wired in parallel.  Each 4 ohm speaker will output 20W,  and the amplifier in my kit can deliver 40W in total.


If you use 8 ohm speakers, or wire your 4 ohm speakers in series, they will each output half the power and your volume will be halved, and you would be adding extra weight for nothing.

There is typically room in the pack under the cyclotron for a 6.5″ or 6×9″ speaker, and by the powercell there is room for a 4″ speaker.  A 5.25″ speaker may fit near the powercell however if you face it towards the motherboard, but in this case it would be wise to drill some holes or install a grille to allow the sound to escape.

Other considerations:

  • A bigger speaker = louder + more bass, but also more weight.  6×9″ speakers are MUCH heavier than 6.5″ speakers.
  • Every 3db increased sensitivity = double the volume!
  • A wide frequency response is desirable, and 2-3 way speakers for cars come with a built in tweeter or two which makes them ideal.

As for specific recommendations, I used to recommend the Pyle Blue label, as they are low in cost and are among the highest in sensitivity, but the ironically named Phantom Boss Ghost series in the same price range appear to be slightly better.

The Boss Phantom Skull are also good, and appear to be identical to the Ghost and come in a few sizes the Ghost does not, but they have red LEDs on them that are synchronized to the music. You could paint over the LEDs or cover them in tape, but the most obvious exposed wires leading to them also power the tweeter and the wires that go to the LEDs are tucked in under the tweeter and very hard to get at.

If money is no object, I might try to squeeze a 6.5″ and 5.25″ speaker in there. If money is an object, or weight is an issue a single 6.5″ speaker would be adequate, and you could sell the spare since they’re sold in pairs, or a pair of 5.25″ speakers might be a good choice.  If money and weight are no object, a 6×9″ speaker and 5.25″ speaker would be the loudest. But proton packs are heavy as it is, so a single 6×9″ speaker may be a good compromise for weight and loudness. It’s really up to you.  There is no best option!

Most in the past I believe have gone with a single 6.5″ speaker, and those that want more have been using a 6.5″ and 4″, but I’m not sure the 4″ is really worth it after installing one in my friend’s pack that I use for demos.  I didn’t drill holes in his motherboard for it though.  A properly installed 5.25″ would certainly be an improvement however!

Positron Prototypes Ready for Manufacture!

Finished the last of the design work on the Positron Proton Pack kit today!

Switch Module
LED Module
Extension Module – Connects to CAT5 cable and fits inside thrower handle.
RGBW Strobe – Color changing main strobe for both proton pack and trap kits.
White Strobe – Used for grille light upgrade and/or n-filter, and can be added to trap kit .
Trap Kit Bargraph – A variation on the normal bargraph which may or may not feature in the final kit. Only difference is it includes a location for one extra LED.

Positron Strobe

Finished the layout for the color-changing (RGBW ) strobe today:


You may be wondering why it has mounting holes.  The mounting holes aren’t there to attach it to the acrylic tube!  They’re there because the same strobe will be featured in the trap kit I will be releasing soon after the proton pack kit, and because I will be modifying this design slightly to create a white version for the super bright grille light.

The Fresh Positron of Bel-Air

Now this is a story all about how my PCB got flipped, turned upside-down!


I was putting the finishing touches on the Positron’s layout the other day when I decided to fix something that was nagging me for quite a while.

When I began working on the Positron, I placed the power connector along the bottom of the board near the 5V regulator.  This location made a lot of sense, both from a power distribution standpoint, and because the main power switch, which is attached to the cable, is usually placed towards the bottom of the Proton Pack.

As I progressed with the design however, and I determined where it would be best to place the CAT5 connector for the extension cable and the connector for the speakers relative to the chips that drive them, I realized I had a problem.   Both these connectors ended up at the top of the PCB, but both also connected to things that would be towards the base of the Proton Pack.

In addition, the CAT5 is the heaviest and the least flexible of the cables, so having it exit to the north and then do a u-turn to head south wasn’t ideal for a variety of reasons.

It was at this point in my thought process that I realized when people went to install the kit  they were either going to mount the board upside down or sideways in order to better orient the CAT5 and speaker cables.

That would make it hard to read the stencils, but even worse,  it would mean the power connector would be oriented towards the top of the pack, opposite the direction in which it needed to go to head towards the power switch at the base.

Thankfully, when increasing the size of the bulk capacitors I had to increase the size of the board, and this extra space enabled me to shift them to the top of the board and place the power connector alongside the speaker connector!

Long story short, I decided that it would be best if I rotated the board 180 degrees, flipped the stencils, and mounted the power connector on the bottom alongside the speaker and CAT5 connectors.


Positron Switch Harness + Charge Port Cable


Power switch harness and charge port cable add-on for the Positron Proton Pack Kit.

Designed to be used with the 12V rechargeable LiPo battery packs you can find on ebay.

No soldering required!

Switch harness is 6′ long with the switch mounted in the center.  Charge cable is 3′ long. 

Arcoelectric toggle switch is extremely rugged, and attached to the cable with quick connects.

Positron Layout

Thought you guys would like to see the latest and near-final layout for the Positron’s PCB!

Final Positron PCB Design

As you can see, a lot has changed since the first prototype:

First Positron Prototype

Among other changes, the audio system has been overhauled, with a dedicated high PSRR regulator for the DAC to keep noise in the system to an absolute minimum.

In layman’s terms, a Digital to Analog Converter converts digital data to an analog  audio signal for the amplifier.  And that DAC is supplied with 5V from a linear regulator from the 12-14.4V primary supply.  This regulator has a high Power Supply Rejection Ratio which means that any voltage swings on the 12V supply will be reduced by a factor of 100 before reaching the audio system.

You may also have noticed the board has increased in size.  The original was 2.25×1.5″.   The final board will be 2.5×1.75″.   I needed the extra room for the Cat5 cable connector, but that allowed me room to improve the routing, increase the size of the bulk capacitors, and add a dedicated connector for the volume control.  I also beefed up the power connector slightly.

The I2C connector pictured above is where you will connect the Flat Flex Cable for the powercell (or bargraph on the eventual trap kit).  Directly above it is the Cat5 cable connector which goes to the thrower and the modules in there.

The SPI connector in the center won’t be populated, it’s for future expansion.  In the trap kit, it will be used to drive a color changing strobe if desired.  The ISP and TX/RX connectors also will not be populated, they are for programming and debugging.  I am undecided if ports 1-6 will be populated.  They are for switches and I currently have no plans for any feature which would require adding switches to the pack itself.  All the switches for controlling things will be in the thrower, aside from the main power switch, and optionally, the volume pot.

Ports 8-12 will be populated of course, with their primary purpose being triggering the relays on a fog machine upgrade.  They will also trigger when different weapons are activated.

While I’m listing features,  I may as well mention just in case you’re unaware that there’s a 20+20W amplifier on board which is capable of driving 40W total into two speakers with a 12V supply.  That’s 4x what other kits can supply, and it’s as loud as the Lepai amplifiers that were often used with my previous kit.  The smaller Dayton amplifiers that were also often used with my old kits were 15+15W.

Positron LED cables


Just got in the new connectors and ribbon cable for the slo-blo and cyclotron LEDs! 

The cyclotron LEDs will be attached to a 16p cable that splits into four at the end while the slo-blo pictured above above is just a single six inch long 4p cable. 

The six pin cable above is one of the old kit’s ribbon cables.  I placed it there as a size reference so you can see just how much smaller the new ribbon cable connectors are. 

Only the cyclotron and slo-blo LEDs will be attached with ribbon cables.  Other individual LEDs will use 2p JST PH connectors, and all the modules will connect with the 6p flat flex cables seen in previous updates.

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