Mega Fart Blaster

Fart Blaster is sure a fun toy, but a bit lame in original form. So let's boost it a bit. Mega Fart Blaster...

1. Fart Blaster toy. I bought mine from Internet Marketplace. ~5eur

Tools:

1. Soldering iron & solder
2. Screw driver (for opening Fart blaster, and connecting assembly screws).
3. Pliers for cutting wires.
4. Insulating tape.
5. Access to 3D printer. Parts should fit on 20cm X 20cm bed, so basic printer is ok.
6. Autodesk Fusion 360 was used to make 3D model of mechanical parts.

Mechanical:

1. Access to 3D Printer, or you can also buy ready-made prints. .stl files are attached below.
2. ~1kg of filament for printer.
3. Paint to get extension part to match original color. Optional, sand paper, filler paint.
4. ~30 pieces PT screws to connect plastic arts together. Size ~4mm X 25mm (some coarse thread screw for wood is perfectly fine too)
5. 8 pieces of M5X25 bolts + nuts to connect speaker to mechanics. NOTE: if you need to use many spacers to fit your speaker, then longer bolts are needed.
6. Metal stripe (or something else) for connecting battery pack inside mechanics.
7. 2-sided tape to connect amp board to mechanics (I connected AMP to speaker magnet pot)
8. Plastic plate (or something else) to connect On-Off -switch.
9. Paint

Electronics:

1. 12 inch Speaker. Guitar amp speakers are perfect for this. They are wide-range -speakers, and typically very sensitive too. Mine is Peavey Blue Marvel 12" 16ohm.
2. Amplifier; I used 30/60W Mono amplifier module (TPA3118 based). Cost ~3eur
3. Battery pack; I used 6 pieces of 18650 Li-ion cells from old laptop battery. Battery holders are also handy with these cells. I used just tape to keep them together. NOTE: Using some ready made battery pack is also possible, and maybe safer if you are not familiar with Li-ion cells.
4. 6s Li-ion BMS (Battery Management System) These are available from many places. Cost 2eur.
5. Power Supply for Charging; ~25VDC. Couple of amps is enough.
6. Potentiometer ~1k ohm
7. On-Off -Switch
8. Some electric wire for making connections.

Print 4 pieces of Mega Fart Blaster segments (files below). 4 parts are needed for complete assembly. About 250grams of filament is needed for each segment.

After you have printed parts, you can connect them together with PT screws.

Then you can test if there is enough space inside for your speaker and electronics parts. If not, print one set (4 pieces) or spacer sectors. Put spacers between speaker and housing, and check again. If there is still not enough space, print more. For me one layer of spacers was enough.

Paint the speaker housing.

If you want, you can sand it a bit to get nicer surface.

You can also use filler paint to get rid of small defects / print artifacts.

Then just paint is few times.

I ended up buying paint from Car paint Shop. They can even measure the color of the Fart Blaster to match paint perfectly. I selected from color samples, and they made paint accordingly.

I didn't paint spacer parts. They are quite slim and there is anyway black speaker rim next to spacer.

You need to get speaker wires of original Fart Blaster to extension part.

Open the "speaker grill" of the Fart Blaster.

1. Open 3 screws of the grill.
2. Work the grill (gray plastic part) out gently by pulling it out around edges.
3. When it pops out, you can see the original speaker and connecting wires.
4. take out the original speaker and use soldering iron to detach connecting wires from the speaker.
5. Connect extension wires to speaker cables.
6. Make hole to a gray part to pull those wires through. NOTE: Make hole into middle, where there is a hole in Speaker Housing Assembly.
7. Then connect gray part back to Fart Blaster with those 3 screws.
8. Now you have a Fart Blaster where speaker wires come out from the middle of the grill.

Match the Speaker housing on Fart Blaster grill.

Pull those speaker wires through hole and then connect speaker housing with screws to Fart Blaster Grill (that gray part where original speaker was connected).

I didn't make any screw holes for those 3D printed parts. You can drill holes to prints, and then mate Fart Blaster and printed speaker housing.

Glue can be also used here, but then disassembling might be difficult.

Here is attached a picture, where electrical connections are described.

Fart Blaster speaker drive voltage needs to be lowered down to a level, where amplifier input is not overdriven. I used potentiometer of 1k ohm to get level down. If you have access to an oscilloscope, you can check that input level is ok. If not, you can hear from sound when input of the amp is too high -> distorted sound.

I used long wires, so that system is easy to test , and every part is easily accessible.

Switch and charging connector I attached to one of those tube -like openings. 1mm plastic plate was screwed on hole, and then holes for switch and charging connector were made to that plastic part. Here you can improvise, since many kind of connectors and switches are available.

Battery pack with BMS I connected with metal stripe into bottom of the housing. Screws through metal stripe holes into printed parts.

Then when everything is tested and connected, connect the speaker with 8 bolts (and spacers if needed) to a housing.

Enjoy! Now it is loud enough!

What could be improved.

1. I used 16ohm speaker. 8 or 4ohm speaker should be louder.
2. You can make an external input, so that this thing can be also a mobile speaker system. Just add 3,5mm connector, and switch to route connection to that, instead of fart blaster output.