Wednesday, March 12, 2008

Power supply

These points should all be implemented while building the power supply:
  • the unit must be positioned into a movable box
  • the unit can be positioned in any way even upside down
  • input: one socket powers the PSU
  • output: one socket with 5V and 12V output power lines
  • it must be possible to add more output sockets in future
  • one switch to turn on or off the PSU
  • each output socket has a 2 LEDs showing if the 2 output lines works (a yellow LED for 12V and green one for 5V)
  • the USB expansion card is positioned into the PSU
    • the box has an USB socket to connect to the PC
    • one LED shows if the USB card is powered (the power is takes directly from the USB card)
    • one DSUB 25pin socket to connect the master to the USB expansion card
    • it must be possible to add more DSUB sockets in future to connect more master cards
  • the box must have a cooling fan
I have bought a box for the PS from OBI: it is a tool box that costs around 9 euro.
I am going to build the PS into such a box by installing cables, sockets and LEDs as specified by the requirements written upon.

The observatory where I work has a disposal area where they put old PCs and old hardware before throwing away. I went there a couple of times and I have taken an ATX power supply from an old broken PC. This will be the core of my PS because it produces stable 12 and 5V power lines.
The only items I have to buy are the sockets (especially those bringing 5V and 12V lines), the USB connector and the DB25 poles to connect the USB card to the remote master.

The following picture shows a schema of the PS. Red lines are power lines. Blue lines represents computer data flow. As you can see the PS has only one power socket and one DB25 socket but there is enough room to add more in future.
The switch to power on/off the PS is not shown but it is close to 220V input line.

Some pictures will be added soon showing the building process.

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