Got an ATX power supply left over from your PCs? This board turns it into a working environment for experiments with Eurorack modules. All it needs is an existing (high-quality) ATX power supply.

Features

• Two Eurorack sockets are available for powering modules (J4 and J6). More than two modules can be operated simultaneously via distributors (not included).
• The board respects the power-good signal of ATX power supplies and only allows switching on if such a signal is present.
• Two USB ports are available for operating separate tools or experimental boards (e.g. Arduino).
• All voltages are switched high-side via MOSFETs so that a common ground is always used.
• Glass fuses isolate the power supply and circuit quickly and effectively. One LED per channel indicates the status.
• The four output channels +12V, -12V, +5V, GND and additionally +3.3V are designed as breadboard-compatible IDC sockets.
• A jumper is available for each channel (J5, J7, J8, J9), which can be disconnected and a current meter can be connected in between to measure the respective current consumption.
• The board can not only be switched on manually via switch SW2, but also via jumper J14 (a power good signal from the ATX power supply is required).

Usage

Preparation and recommendations We recommend mounting the ATX2ER board on a solid surface. We like to use a slightly larger piece of wood on which the ATX power supply unit can also be weighted down.

The board can be attached using M3 or M3.5 screws and appropriate spacers. In the example we use M3.5 x 16mm screws and M4 x 7 x 6 spacers.

The board allows to use regular Eurorack modules with self-developed circuits on breadboards and other USB-powered gear.

The jumpers for the current measurement (element i in the diagram) must be closed in order to supply the plug-in terminals (h) with current.

The fuse holders should be fitted with 500mA slow-blow. Higher currents can also be calculated. However, we recommend not exceeding 500mA, which is usually sufficient for operating numerous modules in the Eurorack area.

Jumpers behind the breadboard terminals allow the current to be intercepted and an ammeter to be inserted into the loop. This can be helpful to monitor the current consumption behavior.

If there is a choice, a high-quality ATX power supply should be used. Too simple or particularly small models from small PCs can transmit unwanted interference signals into the circuits via impure voltages. When selecting the ATX power supply, you should also pay attention to the maximum current supply on the -12V rail. If 200mA or more is specified here, there is a good chance that the power supply is very well suited for the purpose at hand. However, power supply units with lower specifications are not fundamentally unsuitable. However, the low load capacity should be kept in mind when troubleshooting later. Troubleshooting

Noise / unclean signals Some ATX power supply units supply high-frequency interference signals on the current-carrying channels, which are transmitted to all connected components and can lead to considerable interference. If this happens, try a different ATX power supply.