ST2VGA Adapter – Atari ST/STE/Mega ST/Mega STE VGA Converter

Connect your Atari ST, STE or Mega ST to a modern VGA monitor

The ST2VGA Adapter (Revision 3) is a passive VGA adapter for the Atari ST, STE, Mega ST and Mega STE. It plugs into the Atari monitor port and outputs a clean analog VGA signal to any multisync monitor that accepts the original 15 kHz horizontal sync used by the ST color modes. No scan doubling, no scaling, no external power. The ST's native timings are preserved, so the picture looks the way the hardware always meant to look. Revision 3 is a 4-layer PCB design with dedicated RGB low-pass filters that produce a noticeably sharper image than earlier hobbyist boards.

Ships from Spain. For the Atari ST, STE, Mega ST and Mega STE.

Key features

• 4-layer PCB design: dedicated ground planes, controlled signal paths and improved shielding between channels. Cleaner analog video than typical 2-layer hobbyist designs, with less color bleeding, ringing and crosstalk.
• RGB low-pass filters: analog filtering on the RGB lines tames the high-frequency noise modern LCDs amplify. Smoother colors, cleaner edges, less shimmer.
• Color and mono slide switch: a built-in slide switch toggles between color modes (ST Low and Medium) and mono mode (ST High) on the fly. No software, no jumpers.
• Native Atari timings preserved: no scan doubling, no scaling, no upscaler chip. The original Atari video frequencies and the classic look go straight through to the monitor, with no processing latency.
• 3.5 mm audio jack: the Atari mono audio signal is routed to both left and right channels through a standard 3.5 mm jack. Speakers, amps, capture devices, headphones, plug-and-play.
• No external power required: the adapter runs entirely off the +12 V rail provided by the Atari video port. No USB power cable, no charger, no extra plug. Just the adapter and a VGA cable.

Choose the right ST2VGA

Two adapters, same family, different jobs. Pick the one that fits your machine.

Installation

1. Plug the adapter into the Atari monitor port.
2. Plug a standard VGA cable into a multisync monitor.
3. Set the slide switch to color or mono.
4. Power on.

No soldering, no modifications, no tools.

Compatibility

Color modes (ST Low and ST Medium) require a VGA monitor that accepts a 15 kHz horizontal sync signal. Mono mode (ST High) works on any standard VGA monitor. The 15 kHz reference list is the most practical starting point if you are unsure about a monitor.

Specs

• Weight: under 50 g.
• Dimensions: approximately 38 mm x 45 mm x 36 mm.
• Power: passive, fed from the Atari video port (+12 V rail).
• Atari connector: DB-13W3 (Atari monitor port).
• Output: VGA-compatible (multisync monitor required for color modes).
• Audio: 3.5 mm stereo jack (mono routed to both channels).
• Horizontal sync: 15 kHz (ST Low and Medium), 31 kHz (ST High).
• PCB: 4-layer, RGB low-pass filtering.

Frequently asked questions

Which Atari models are compatible?
Tested on the Atari 520ST / STF / STFM / STE, 1040ST / STF / STFM / STE, Mega ST and Mega STE. Some very early Atari ST boards do not expose the +12 V rail on the monitor connector that this passive adapter needs to operate. If yours is one of those, use the ST2VGA Enhanced Adapter, which carries its own +5 V supply over micro-USB.

How hard is it to install?
Plug the adapter into the Atari monitor port, plug a standard VGA cable into a multisync monitor, power on. No soldering, no modifications, no tools.

Is there a 3D printable enclosure?
Yes. Enclosure files and links for the ST2VGA family live in the ST2VGA family enclosures page.

Can this damage my Atari?
No. The adapter is electrically safe and places minimal load on the Atari video circuitry.

Is this a scan doubler?
No. The adapter preserves the original Atari scan frequencies and timings. No upscaling, no scan conversion, no processing latency.

What video modes are available, and what monitor do I need?
Color modes (ST Low and ST Medium) require a VGA monitor that accepts a 15 kHz horizontal sync signal. Mono mode (ST High) works on any standard VGA monitor. The 15 kHz reference list is the most practical starting point if you are unsure about a model.

How do I switch between video modes?
A slide switch on top of the adapter toggles between color modes (ST Low and Medium) and mono mode (ST High) on the fly. No software needed.

My display shows jailbars or fails to lock. What now?
If your monitor already accepts 15 kHz but you still see vertical jailbars or frequent sync drops, move up to the ST2VGA Enhanced Adapter. Its buffered RGB amplifier and extra filtering were built specifically to clean up marginal signals and keep picky LCDs happy.

How is audio handled?
The adapter includes a 3.5 mm audio jack. The Atari mono audio signal is duplicated on both left and right channels.

Are special VGA cables required?
A standard VGA cable works. For best results, a cable with ferrite noise filters is recommended, particularly on longer runs.

Good to know

• Passive, plug-and-play, no external power supply. For color modes you need a 15 kHz-capable multisync monitor.
• For an early ST without +12 V on the video port, or if you see jailbars or fail to lock, use the ST2VGA Enhanced Adapter instead.
• Homebrew product built for hobbyists, not a sealed appliance.

Certifications and compliance

This product has been assessed for European (CE) and UK (UKCA) conformity. Official Declarations of Conformity and EMC Assessment reports are available for ST2VGA REV3.4.0: EU / CE Declaration of Conformity and UK / UKCA Declaration of Conformity.