Bring Your Own Phone Line Voltage

If you want to play Dreamcast or Saturn games online via dial-up modem, you’ll need a live phone line (with electrical current running through it) in order to carry the analog phone signal from the Dreamcast/Saturn Modem over to the USB Modem connected to DreamPi or PC Server. Live phone lines were once common in every household across the globe, however, today we have to “fake it” and create our own. There are two common options for doing this:

OPTION A: USB ‘Live Modem’ Mod – In order to get your Saturn (or Dreamcast) online, you’re going to end up needing one of these USB modems anyway, so why not just add the telephone line voltage directly to the USB modem itself? Turns out a Dreamcast-Talk member, Tact, had this exact idea and built several of these for the community, before pcwzrd ultimately started selling them on the Dreamcast Live Shop. In fact, he still currently offers a modding service where you send him your existing USB modem, and he’ll add line voltage for $19.99.

* (If you happen to be a bit faint of heart with a soldering iron, then you might be interested in going this route…)

However, if you are comfortable soldering, and you’re the DIY type, then you can follow along with this wiring diagram/guide to add phone line voltage to a ZOOM 3095 (or clone) USB modem. You will need the modem itself, as well as a small list of parts that can be purchased relatively cheap.

^ These parts & their respective links are just a recommendation. They’re what we’ve used, tested and know to be working for this mod. If you’re able to source alternative parts with equivalent specs, you may choose to do so, however, if you plan on following the diagram below verbatim, then you might be better off grabbing the parts listed above. (these are not affiliate or sponsored links – they’re just the parts that we sourced for this guide)

NOTE: It’s very important to keep all wiring short and neat, in order to allow the voltage booster board to fit snugly inside the case and be able to screw it back together. It’s also recommended to place a small piece of electrical tape over any chips or solder pads on the main board (as shown in the example image) in order to avoid any direct contact with the mod itself.

OPTION B: VoIP Adapter + Splitter – Before the NetBand Tunnel, folks were using Linksys VoIP adapters as a crude (and terribly slow) means of playing Saturn online, so some may already have one of these lying around. Believe it or not, these (and most VoIP adapters) actually generate continuous line voltage when they are connected to power but not connected to ethernet. All you need to do is plug a phone line splitter into the VoIP adapter, and then send one phone cable to the NetLink Cartridge and another phone cable to the USB modem. Voila! You’ve got Line Voltage!

(Disclaimer: This solution works fine, but it’s probably the messiest solution (with the adapter, splitter, phone cables, power brick, etc…)
If you prefer a cleaner looking setup, consider options A or C)

OPTION C: Build a Line Voltage Inducer – A line voltage inducer (or LVI for short) essentially ‘injects’ phone line voltage into your existing phone cable. If you don’t want to spend the money (and you have basic soldering skills), you may wish to go this route. It may not be quite as clean as opting for the self-contained Live Modem, however, you can make it as neat and tidy as you wish… You may even find individuals on Etsy or eBay selling them pre-made (subject to availability).

DIY Line Voltage Inducer

Here, we’ll show you how to build your own Line Voltage Inducer, and to do so, you’ll need the following components:

  1. RJ11 telephone cable (10-15 ft.)
  2. 0.47uf electrolytic capacitor
  3. 330 – 380 Ohm resistor
  4. 9v battery connector
  5. 9v battery
  6. Solder (and soldering iron)
  7. Heat Shrink (or Electrical Tape)

First, you will cut the outer shielding from a 3-4″ inch length of the phone cable (be careful not to cut the wires inside).

Inside the cable, you will typically find four wires (red, black, green & yellow – we will be dealing with the red wire only and leave the others alone). Cut the red wire in the middle and strip the ends of the red shielding so that the wire is exposed at each end.

Then, connect the electrical components by soldering them according to the diagram below:

It’s best to apply heat shrink where any two wires have been soldered in order to properly insulate the connection, however, electrical tape may be used as well. Once all components have been assembled and shielded, you may wrap the entire area of the cable with heat shrink or electrical tape as well.

If you prefer a tidier result, you might consider picking up a cheap phone line coupler from Amazon or any hardware store, crack it open, and perform the above soldering connections to the red wire housed within.

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