Searchlight_ATX

Searchlight ATX is in the concept phase. Standard PC computer interfaces are robust, easily available, relatively efficient, and very cheap (due to huge volumes) for the power output they provide. Several people have successfully converted these for use in powering model railroads and other systems.

This project is an attempt to "do it up nice", with a few features.

Features / Requirements

• Designed around the ATX12V standard
• 12V2 output boost converted to 18VDC for powering DCC command stations and boosters
• MRR-convenient connectors for 12V and 5V regulated accessory power
• On-board and remote Power good indicators
• Remote "soft" power on/off switching
• Dummy load
• Nice, clean, "plug and play" design with laid out board and proper connectors.
• No-soldering required for installation
• No modification of the power supply required for installation.

Disclaimer

Since this project involves adapting the outputs of a device for purposes for which that device is intended, I'm warning you now. Use this information at your own risk. The author neither warrants nor claims to be useful for any purpose this design. If you try it and fry something (including, but not limited to yourself), don't come crying to or yelling at me. You've been warned.

Description / Explanation

Power supplies for use in computers are designed to meet standards published by the motherboard and/or chipset manufacturers. One such standard is the ATX12V standard published by Intel. This standard is for use with their newer chipsets that require 12V power on the motherboard.

A typical such power supply has the following interesting and/or useful features:

• High power. A "cheap" PC power supply starts at 150W, and 300-400W units are easily available at relatively low cost.
• High efficiency. Minimal efficiency standards are around 70% for no/low load, and go up as the load increases
• Convenient outputs: ATX12V has two independent 12V outputs, plus a 5V "always on" and a 5V "soft switched" output.
• Power Saver: The ATX12V has a "power on" signal that can be wired to a remote switch for shutting the supply down remotely.

Unfortunately, as-designed, the power supply has a few correctable problems:

• 12V maximum output voltage. Popular DCC hardware (Digitrax, for example) works better at 15-18V DC input.
• Odd connectors. The output connections are designed for plugging into a motherboard, not for easy use by a modeler.
• Minimum-load shutdown. Most PC power supplies are designed to go into a shutdown mode if there is less than a minimum load applied.