Project Unity

PDF of the V1.0 pcb

Project Unity is basically going to be a new PCB for the Atari 2600 that will feature a video mod, audio amp, power conversion circuity, and controls. This will enable a much smaller format for portables and make it easier to make a portable for beginners in the hobby.

I hope I got the connections right. This is the first time I have designed something this large. Videos mods are easy to separate the Digital and Analog components (resistor ladder separates them well). I should have added more ground planes on this but its a prototype so its mainly for testing purposes. The only thing I am worried about is the power converter (switching regulator type Ti PTN4050) might be a bit to close to the clock signal for the Atari but its buffered by a couple 100uF caps so it should be ok.

The board measures 4.65″ x 3.45″. Has built in power converters (to up a 3.7V Lithium Cell to 5V), audio amp, video mod, and controls for the left player. Stereo jack, right and left difficulty switches, black and white switch (some games use this as a control). Only thing it misses is the Right control port as Serial ports are dam huge.

Everything soldered in place. Some stuff needs to be replaced but its working!

Ok the board is going to need some revision. The video circuity needs to be placed on the other side of the board along with a page worth of issues. Good thing the prototype at least works. All these issues are just nitpicks of mine.


After the success of my first two portables decided to start shrinking the size of my portables to something that would be easier to carry around. For V3 of the NESp I am going to base it off a NOAC (Nintendo On A Chip) board. A NOAC is basically a chip that emulates how a real NES works. The advantages are that it reduces power consumptions of the portable and it makes it smaller. However NOAC’s are not 100% compatibly with every single game (about 3-5 games don’t work).

The NOAC that will be used for V3

Design Goals
Make it as small as possible
Use a 3.5″ screen
Smaller footprint then the PSone 5″
Large enough to easily see whats going on
Pre-LED modded
Minimum of 5 hours of life
Lithium battery 1600mAh

The NOAC is comprised of 3 boards. The board on the left is the A/V plugs and DC input. The middle board is where the NOAC is located and the right board is where the controllers are plugged in. The only board necessary is the middle board.

The total size should be around 6.5″x4″x2″ which is roughly half the size my previous portable (SNES V1) is.

Finished the design today. Turned out pretty close to what I wanted it to be. 6.5″x3.5″x2″

I finished the case. Turned out pretty good I think. Looks a lot like a wooden brick. The buttons and D-pad are done but I didn’t take a picture of those.

Here you can see the two input jacks. The one of the left will be headphones and the one on the right will be the recharge jack.

Finished hacking the NOAC and LCD screen today.

The controller board has to be removed so the screen will fit in the case. The board contains the inputs and other various controls for the LCD screen. These have to be soldered directly to the driver board for the screen. The board on the left is the controller board and the board in the clamps is the driver board.

The trim pots control the brightness, color, and contrast. Removing the control board reduced the overall thickness of the LCD screen from 1″ to 1/2″. The inputs and trim ports where connected directly to the driver board with 24AWG solid strand hook up wire. The driver board has convenient soldering pads for this.

To fix the LCD screen into the case I used some hotglue. After I install the controls and buttons I will fix the trim pots to the case.

The NOAC was attached to the case with hotglue and soldered to the LCD screen. Slowly starting to get somewhere with this portable.

Back with good news. I finished the portable and I am now testing it.

Well enough with the guts.

The case turned out much better then I had expected. At first I didn’t like how I rounded the corners but the more I play the portable the more I like them.

The power button here is epoxied to the top of a large tact switch.

I received a suggestion to make the D-pad out of 1 solid piece of wood. I will look into it the next time I build a case.

Since the portable is so small the controller boards took up all the space on the front panel so the speaker had to go here.

This volume slider is probably my favorite new feature of my design. Expect to see it in upcoming portables.

The one on the left is the headphone jack. It automatically switches the sound to the built in speaker off when you plug a headset in. The jack on the right is the charger. It also disconnects the battery from the main circuity when you charge the battery. The portable is unplayable when charging but it is safer when charging lithium batteries.

I really like these hex headed screws. They look much better then the normal stainless steel machine screws that I previously used.

Being the first portable I built with an AEIComp LCD screen I was very impressed with the quality of the screens. They are bright, clear, and sharp.

I am slowly refining my portable designs. In my next portable I am going to make the guts of the portable as streamlined as possible. Even though no one sees the insides it is just nice not to have a nest of wires to deal with.

Atari Flashback P V1

Basically this portable will be a portable Flashback 2 with cart slot. Looking to have all the features of a normal Atari built in. Including all the switches and joystick port.

So far the Flashback Portable is working quite well. Cart mod, chopped down, video working, audio working, and it runs off of 4 rechargeable AA batteries (4.8V) with no voltage conversions.

The first Work In Progress video so far. This portable will be featured in a couple videos as I hope this will drum up more traffic for the site.

So I am waiting on the parts for the electronics I will work on the case a bit. The case is made out of aluminum bar that is 1/16″ thick. Bent it with a sheet metal break then epoxied the wood front on top.

Going to buy a 3.5″ screen for the portable as the 2.5″ screen is tiny.

This is a work in progress for my Flashback portable I have been working on. Part two. It is 100% working on the electrical side. Case construction will be finished when I get the new 3.5″ screen and redo the screen hole. A couple switches need to be mounted and the like but its close to being done.

Done with the electronics for the Flashback Portable. 3.5″ LCD finally came state side. Next step I have to do is to stick the guts into the case.

Finally got that blasted 3.5″ screen in. From now on I am sticking with AEIcomp. Sure its more expensive but the screen quality is better and shipping only takes a couple days. Anyways on to the case!

Man that 3.5″ screen looks TO big now haha.

The second player port. Took awhile to file that slot out but it looks nice. Needs a bit more sanding before I finish the case out.

That is the headphone jack. Right next to it will be a knob for volume and the B/W switch. I am going to try to finish up the case tomorrow. Just need to cut a couple more holes and then polish the aluminum up and lacquer the wood. There is some internal stuff to build so I will try to get that done tomorrow to.

The Flashback portable is almost done. Should be finished in about a week.

The metal tabs are going to be drilled then tapped so the back wooden panel can attach to the case.

The d-pad and buttons.

Controls installed today. The screen isn’t not turning on however. Hoping its not broken.

After some delays and broken screens it is finally done.

The final pictures.

The portable sports a 1000mAh battery for an average battery life of around 6-8 hours. Around 40 built in games and a cart slot that can play 90% of all Atari 2600 games.

Nintendo Duo V1

Nintendo Duo Portable V1 – Or Duop which is Pronounced “Doowop

This project will be an entry for the “Portable-Palooza” on the Benheck Forums. It could be the first dual NES and SNES portable every finished but I have to check on that.

This project was completely designed in 3D space unlike my other portables. Usually I will draw out the design on paper but due to time constraints I passed that option up.

To start I based the design off of the case design on the dimensions posted by “lovablechevy” on the Benheck Forums. Upon receiving the parts I double checked everything and tweaked the design a bit.

The portable will feature switches that will feel exactly like the button presses on a normal SNES pad (squishy over clicky). Also the portable will know which type of game you have inserted via two switches in the cart slots.

Runs off of 4 AA batteries. Haven’t calculated how long the batteries will last but I guess it will be for around 2 hours.

I finished the design of the portable. I rearranged the components to slim the portable down to the same thickness as my SNESp V2 so I really didn’t have to change much on the design of the case.

After opening the Retro Duo I was to see first hand how small the board really is. Pretty impressive to see how 20 years of tech can shrink down a SNES and NES.

To make the screen fit inside the 4.5″ limit the top section that is used for the back light is chopped off completely. I used a scroll saw then filed the rough edge down.

I desoldered the NES cart slot and board section to I can move it to its new location and bend the cart slot by 90 degrees.

Here is a pinout of the power switch that is on the SNES side of the portable. Pretty simple. This disables the LED lights on the board so I removed those.

I used some bare hook-up wire to wire the cart slot. Since I am not going far I decided this would be the best solution.

I did some testing and found it didn’t work. A couple hours later I isolated the problem to a little tiny cold solder joint.

The NES side of the portable draws 370mA. Taking in efficeintcy of 80% and a 4.8V power source, 4 AA NiMH 2600mAh cells, I found that the portable will last 3.6 hours on one charge.

The SNES side draws only 640mAh. Using the same criteria as the last calculation I got 2.1 hours on one charge.

Worked on the case today and got most of it built.

I used a scroll saw to cut the rough outline of the screen opening and speaker areas. I do this because it is allot easier to get a straight edge by filing down the edge to the line then it is to cut it.

After a few hours of filing and sanding I came out with the finished front panel. The mahogany strips for the speaker covers are just wood glued in.

The trick is to glue the front panel and the sides together at the same time. This insures that the case is square.

While the case was drying I cut out the buttons for the case. To cut them I use a zero taper plug bit. The D-pad is rough cut on the scroll saw and then filed down to the correct size.

This is how the PCBs will stack up inside the case. I changed the design a bit and managed to squeeze the whole thing in a case the exact size as the SNES V2 case.

I finished the case Saturday night. Sanded it down with 220 grit and then applied 3 coats of Lacquer. The mahogany turned out ten times better then cherry does.

After waiting overnight for the lacquer to dry I stuck the guts into the case. I mounted the screen first and then the SNOAC board and then the NOAC came last. Each one has a layer of electrical tape to prevent shorting between boards.

I found a better tact switch style. It has a rubber dome that feels exactly like a normal console controller would feel.

Only a couple more days left on on this portable. I have to wait till mouser sends me some more tacts tho.

Been doing allot of work on the Duop. I finished the controls and the power circuit today. Unfortunately the SNES side of the portable started acting up. It was like interference on the video line but the NES side was fine. I looked for spilled solder, tried larger wires, rerouting wires, cold joints, ect.. and no dice. I turned it on this afternoon and it refused to turn on. There is sound but no video on either the SNES and NES side.

This is a controller IC from a retro duo controller. I cut it out this the scroll saw and filed it down. Was allot easier then making one out of two 4020s and a handful of resistors.

Because I redesigned the case where both carts can be inserted at the same time a switch in both cart slots to switch which one is inserted as the Duo would get confused and freak out. So I installed a little slide switch. The switch will have a wooden top and will blend in with the rest of the case.

Good ole PTN04050. Will boost the 4.8V from the batteries to a good solid 7.4V with 90% efficiency.

Well because the Duo died I won’t be entering this into the contest. When the new one comes in this portable will be finished as I can drop the Duo in after only a little bit of hacking.

Been awhile since I have worked on this but now its done! After fiddling with the AA batteries I came to the conclusion that they can not provide the amperage needed to power the Duo beast. So I ordered a 4000mAh 7.4V Lithium battery which was the largest thing battery I could replace the 4 AA’s with.

So the battery I ordered was about the same size as all 4 AA batteries stacked up. To make it fit I had to cut it open and flatten it out.

The battery has 4 lithium cells which are paired up behind a protection PCB. I decided to cut down the middle and tack on some wires so I could separate the two “packs”.

I placed the new batteries inside the portable and removed the PTN04050 from the power circuit as I am going to run the portable straight off the 7.4V battery.

Testing done! Time for the photo shoot!

Final Specs
4.2 Hours of battery life
2 Hour charge time
Plays NES and SNES games
Rubber tacts that feel like a normal controller
Stereo Sound with Headphone jack
Dimensions 9 3/8″ x 5 1/8″ x 1 5/8″

Well that concludes the worlds first portable NES/SNES!

A little game play video of the Duop in action.

Atari 7800 P V1 – Design Phase

The Atari 7800 has a complex and large motherboard which makes it difficult to portablize. Looking at some old schematics that I found on Atari Age. Once Video modded most of the support circuitry for the RF module which cuts the board down significantly.

Finished the Layout of the case and control scheme. I will probably need to tweak it later to make it a bit more comfortable but this will do for now.

The overall case size came out to 5.75″x6.75″x2″ (LxWxH). This is the smallest portable I have designed so far (and it is starting out as the largest console!).

Just the case layout. Instead of using a traditional D-pad I decided to use a multi-directional 4-way switch which is just a fancy term for an Arcade Joystick that is really small. The one I am using for this project is 1/2″ wide and 1/4″ tall, perfect for portables.

The front panels are made out of stainless steel and the sides are acrylic with the insides painted black. Yes I know, not wood. Decided to mix it up a bit on this one.

Cutting Diagram

This is how I plan to cut the 7800 mainboard. After the video mod the entire upper left part is useless. The cart slot will be relocated and the power circuit in the upper right will have to be recreated. In the middle the board will be folded and attached with ribbon cable.

Propeller Development Kit

How to make a Propeller Development Kit

Read through the instructions carefully before attempting. Also read the disclaimer.

I needed a Parallax Propeller Development Board so I could keep working on my projects. Having to pull out my only prop from the pinball machine to test circuits was slow. I looked into getting the Gadget Gangster which lays out the propeller in a form familiar to those that have worked with the Arduino boards and has “shields” being built for it.

However at the time of this writing it was out of stock and I needed the board quickly so I decided to build my own on proto board. The Gadget Gangster is built off a .1″ pitch so copying the layout was easy to do on proto board. I decided that the Dev Board I would make would be much more flexible as I can add on more standard features like an Analog to Digital Convertor without having to add a shield.

I looked up a couple schematics and layouts which I have included below.

Gadget Gangster PCB Layout
Gadget Gangster PCB Layout 2
Gadget Gangster Full Schematic
Propeller Proto Board Schematic – Refer to Pg5.
SD Card Pinout – Not mine, found it on the web.
SD Card Pinout 2 – Look at SPI mode.
Interfaceing a SD card with the propeller

Besides VDD and VSS on the SD card every data line (CLK, DO, DI, RSV) should be pulled up to VDD with a 10k resistor.

Here is a incomplete parts list for the project. It just includes all what you will need. Some stuff like capacitors are not on the list as I had those on hand.

Digi-key Part #’s

1 – P8X32A-D40-ND – DIP Propeller
1 – 101-00405-75-ND – SD Card Slot
10 – CF18JT10K0CT-ND – 10kOhm Resistors
1 – 24LC512-I/P-ND – EEPROM
1 – LM2937ET-3.3-ND – 3.3V Regulator
1 – XC1711-ND – 5Mhz Crystal
2 – S7014-ND – 14 Pin Female Headers
2 – S7002-ND – 4 Pin Female Headers

Some things you will also need. I had these on hand so I don’t have part numbers.

3 – 100uf 16V Capacitors (Electrolytic)
2 – .1uf 50V Capacitors (Ceramic)
1 – Power Connector
1 – Power Switch
1 – 7805
1 – Power LED and Resistor to match for +5V source
1 – Normally Open Tact Switch
1 – 4 Pin Male Right Angle Header

You will also need a 7-12V DC power supply that fits the power jack. I used a Sony 9V DC supply that I had lying around.

This Dev Board also needs the Prop Plug for the USB connection. This can be used over and over again so if you are planning on making several Propeller projects then it is cheaper to go this route.

I would suggest you build the power circuit first and test it with a multimeter to make sure it is operating correctly before hooking it up to the microcontroller. This ensures you don’t ruined your $8 part and have to wait 4 days for the replacement to come in.

For the proto board; Radio Shack sells really inexpensive proto boards. For $4 they sell there 4″x6″ which is what I used for this project.


Don’t sue me for doing something stupid

I cannot be held responsible for any damages that could occur to you, your equipment, your property, or your electronics while following the procedures present on this website. Any acts of God(s) or stupidity caused by you is not my fault or problem. Please note that the procedures on this site have worked in my case without any damages or problems. I do not support any of the modifications on this site with any kind of guarantee.

Creative Commons License
All work on this site is licensed under the Creative Commons Attribution-ShareAlike 4.0 International License unless otherwise noted.
The Longhorn Engineer is copyright (c) 2022 to Parker Dillmann.

Sega Neptune

How to make a Sega Neptune

Read through the instructions carefully before attempting to start this project. Also read the disclaimer.

This guide is sponsored by Super Fighter Team.

The first Neptune I built can be found here. Since then I have updated the design to require only one power supply. The Genesis 2 and 32X module can run off of 650mA which is under the 850mA that the stock power supply offers. You may wonder why Sega didn’t just have the 32X draw power from the cart slot or just have a jumper cable running from the back of the Genesis power supply to the 32x? Well the cart slot can’t power the amp hungry 32x but I don’t know why Sega went with a separate power supply over a just a splitter/jumper.

This guide is a step by step overview of how to make a Sega Neptune that only uses one power supply and features region mods. This project may look daunting but it is fairly simple and straight forward. There are no supper tricky soldering situations (unless you do the region mods) so anyone that has moderate experience with a soldering and desoldering iron can build a Neptune.

Sega Genesis 2 with a 32X module on top. Our goal is to squeeze all that into the Genesis 2 case.

For this project you will need the following tools

  • Soldering Iron – 15W-25W
  • Desoldering Iron – 25W
  • Needle Files
  • Assorted Screwdrivers
  • Dremel like tool with Cutting Discs
  • Needle Nose Pliers
  • Hot Glue Gun

Parts Needed

  • Sega Genesis 2
  • Sega 32X
  • Lots of Ribbon Cable
  • 3 DPST Switches (for region mods)
Back of the 32X.

First start by disassembling the 32X. There are a lot of screws so make sure to get them all. Some are hidden on the vertical part of the 32X so make sure to get those too.

Top off of 32X.

After taking the top off the 32X remove all the screws holding the RF shielding and 32X board to the casing.

With all the screws gone the vertical portion of the 32X should slid through the bottom casing. The sides of the vertical portion should then be removed.

Flip the 32X over and find these tabs near the underside of the cart slot. Straighten them out with pliers and flip the 32X back over.

Take a small flat head screw driver and pry the RF shielding off the 32X cart slot. Make sure to be careful and not slip as damage to components and traces can occur.

There are two white ribbon cables that connect the two 32X boards together. Take these ribbon cables off by pulling them straight out of the slots that hold them in place.

Using a hammer, smash the ring to remove it. This ring is used to help prevent data corruption over the ribbon cable and please the FCC but the 32X seems to work fine without it and the 32X needs the space to fit inside the Genesis 2 case. After removing the ring replace the ribbon cables back into the slots on the 32X.

Using a desoldering iron remove the video output from the 32X. Don’t force it as you will have to use this part again. When removed take the metal shielding around it off.

Video output removed and shielding taken off.
Reattaching the video output jack.

Solder some wire about 6 inches long to the video output contacts. I used standard ribbon cable wires for it.

Then take those wires and solder them to their corresponding points on the jack. Its a good idea to test the 32X now. If it fails to work make sure you haven’t bridged a connection anywhere.

Now to disassemble the Genesis by removing the 4 screws that hold the Genesis 2 case together and take the top off.

Take the cart flaps off the underside of the top of the case by removing the 3 screws that hold it in place.

Now remove all the screws that hold the Genesis board to the RF shielding and case.

Some boards have different layouts. This one has the 7805 voltage regulator and filter capacitor right next to the cart slot so it will have to be relocated to the back of the case. If the board has the 7805 located at the back of the board skip the relocation of the 7805 and large capacitor.

The offending 7805 and capacitor.

Flip the board over to the bottom and desolder the 7805 and capacitor. Pay attention to how both where orientated on the board.

Reattach the 7805 by soldering 3 wires of about 4 inches in length to the 7805 and the board. Make sure to get the orientation of the 7805 correct. Use a heavier gauge like 20 AWG for this.

And do the same for the large cap.

Location of the capacitor. Pay no attention to the 7805 as I found a better location for it.

Now flatten the capacitors on the board to reduce the overall height off the board. Just heat up the contacts and pull them slightly to extend the leads a bit then fold the capacitor over. Be careful not to pull the traces off the board or rip a leg off a capacitor.

Now for the tricky part. Desolder the 64 contacts to remove the cart slot on the Genesis board. However, the cart slot won’t come off the board without removing some rivets.

Bottom of rivets
Top of rivets

To remove the rivets take a small flat head and position it like shown above. Push the edge inward. Be careful not to slip.

Edges of the rivet pushed in.

Then take a Philips head screwdriver and push the rivet out of the board. The cart slot should come free from the board now.

Clean the contacts on the 32X by rubbing some fine steal wool on them. This removes the oxidized layer on the metal and makes soldering easier.

Tin the contacts on the 32X. Make sure to use plenty of flux.

Connecting the Genesis to the 32X!

Using ribbon cable attach the 32X to the Genesis. The wires closest to the front of the Genesis need to be cut at 4″ and the other row needs to be 3.5″ in length. This will ensure that the wires are straight and untangled.

On the far side of the 32X the wires need to be attached upside down. When the 32X is folded down on top of the Genesis these wires will lie straight. I should have taken more pictures of this part but my first Neptune I built has some pretty good pictures of this part Neptune. I used thicker wires in that version but the method is the same.

Make 3 aluminum shields. I think I made them 3.75″ by 4″. They are 4 layers thick and covered in packaging tape to prevent short circuits. These help separate the two sets of wires and help prevent cross talk.

Place one in between the two sets of wires and one on each side of the wires like a sandwich. This is a good time to see if the Neptune is working. If it fails double check every connection and inspect the board for solder spills.

Solder some wires to the contacts shown. I cut my wires to be 7 inches long. This is to replace the cable that connects the Genesis A/V out to the 32X A/V in. Attach some heavy duty wire (18AWG) from the power input on the 32X.

Now desolder and remove the video output on the Genesis board. Then attach the wires from the 32X to the exact same spots on the Genesis video output. Make sure to solder to the bottom of the board and leave the top clean. Then attach the power wires from the 32X to the input on the Genesis.

Now take the Video output from the 32X and hot glue it upside down to the old spot of the Genesis video output. The port may be a little high so file down the hole to make it bigger.

Back of the Genesis. Ignore the fact that the power plug is missing...

Double check every connection and test the Neptune. Remember to inspect the board carefully for solder spills. If it doesn’t work the problem most likely lies with your 32X/Genesis cart connection. Check to make sure the wires are straight and untangled.

If region mods are wanted this is the time to do them. The mods are everywhere on the net so I won’t post on how to do them. MMMonkey has a really good guide on MD2 mods and for the 32X head on over to here. The 32X one is in french but google translates it pretty well. I used the simple version. I attached the switches to the back of the Genesis casing.

Location of region mod switchs

Bend the 7805 so it lies on in this corner. You may have to bend the bottom RF shielding to get it to fit.

Can't play doom yet.

Genesis games are smaller then 32X games the cart slot needs to be widened. Place a 32X cart on top of the slot and trace around it with a pencil. File down the plastic till it fits.

Can play doom now!

If you have an import JPN game you will have to cut some more of the cart slot. Use the same method.

Modified cart flap doors.

If cart slot flaps are wanted take the cart slot mechanism from the 32X an cut it down like shown above.

Hot glue these flaps to the inside of the Genesis 2 case.

Use #4 1″ wood screws to attach the 32X to the genesis board and casing. The holes around the 32X cart slot will line up with the holes on the Genesis board. Go ahead and test the Neptune to make sure it works.

Side view of the PCB sandwich.

Place the cover back on the Neptune and test the cart flaps if you have them installed. Most likely the flaps will hit the cart slot. If so cut off the edges of the cart slot with your dremel.

Put the cover back on the Neptune and replace the 4 screws. It is now done.

Some final pictures.

Beggar Prince by Super Fighter Team.
Plays any region!

A special thanks goes out to Super Fighter Team for sponsoring this how to!