Background
Over the past 3-4 years i have become quite exasperated at the number of AC-DC mains adapters for electronic equipment that have failed. The most disappointing thing is that the mains adapters that have failed are not supplied with cheap unbranded equipment but with well known brand names. For example, the 12V mains adapters supplied with the following equipment have failed in this time.
I have decided to produce my own 12V supply for routers, modems, external disk drives etc. Rather than build individual units for each piece of equipment i decided to try to recycle an open frame PSU i had used in a project i worked on a number of years ago.
I worked on the development of an external disk drive for banking equipment which required +5V and +12V. Part of my task was to qualify an OEM PSU for use in this piece of equipment. Part of the qualification process was to run the PSU's at maximum load at an elevated temperature and monitor how they performed. When the test process was completed the PSU's were to be scrapped. I salvaged a few with a view to using them in a project and have had them in storage since 1987/1988.
They are rated at +12V at 3.5Amps so they should be able to power 3 items that require 12V at 1Amp and still have a good margin of safety. I plan to source a suitable casing with appropriate ventilation to mount the PSU and will provide cabling for each piece of equipment to be powered.
The equipment to be powered from this unit will be:
Currently these pieces of equipment are powered from plug top AC/DC adapters.
- Netgear DG834G Wi-Fi ADSL2+ Router. (Two separate units have failed)
- Netgear S101 Network Attached Storage unit.
- Linksys/Cisco RV082 Router. (Two separate units have failed)
- 3Com 3CR858 Router.
I have decided to produce my own 12V supply for routers, modems, external disk drives etc. Rather than build individual units for each piece of equipment i decided to try to recycle an open frame PSU i had used in a project i worked on a number of years ago.
I worked on the development of an external disk drive for banking equipment which required +5V and +12V. Part of my task was to qualify an OEM PSU for use in this piece of equipment. Part of the qualification process was to run the PSU's at maximum load at an elevated temperature and monitor how they performed. When the test process was completed the PSU's were to be scrapped. I salvaged a few with a view to using them in a project and have had them in storage since 1987/1988.
They are rated at +12V at 3.5Amps so they should be able to power 3 items that require 12V at 1Amp and still have a good margin of safety. I plan to source a suitable casing with appropriate ventilation to mount the PSU and will provide cabling for each piece of equipment to be powered.
The equipment to be powered from this unit will be:
- Netgear DG834G Wi-Fi Router.
- Linksys/Cisco RV042 Router.
- Netgear 101 NAS disk system.
Currently these pieces of equipment are powered from plug top AC/DC adapters.
The units i have to hand are Astec SA70-1400. They were produced in 1986 and were used for testing during 1986 and 1987 then put into storage. After a bit of research i found that these particular units and their derivatives were widely used in telephone exchanges and other telecommunication devices around the world and their performance and reliability were highly regarded. In fact many of these units are now available on the surplus and second hand market and many companies offer a refurbishment/repair service.
There are a few tasks to be completed before the unit can be set up and tested.
More to follow......
There are a few tasks to be completed before the unit can be set up and tested.
- Source power connectors and contacts for the mains input and DC output connectors.
- Source power resistors to ensure that the minimum load requirements are met to ensure the unit will function as required. It is common for switching PSU's to have a minimum load requirement.
- Source a suitable casing/housing to mount the unit.
More to follow......