Power supplies, connectors, fan, etc.

I’ve made a small amount of progress on the code, but nothing particularly noteworthy. I’ve given some thought to the design of a 3D-printable enclosure. I’m not sure whether I’ll end up needing a fan. I’ll put ventilation holes in the sides of the enclosure, which might be sufficient. I’d like to put the power supply on the bottom of the enclosure, but without a fan, that will result in heating up the boards above it.

I just placed an order with Mouser Electronics for power supplies, connectors, fan, etc., specifically:

  • Mean Well RD-35A switching power supply, 5V 4A and 12V 1A
  • Qualtek 761-18/003 AC power entry module with switch and fuse
  • Qualtek FAD1-08025CBLW11 80mm x 25mm 12V DC ball bearing fan
  • Qualtek 09325-F/100 fan finger guard and air filter assembly
  • TE 3-350816-2 quick-connect crimp terminals (for AC power entry)
  • Molex 19142-0024 spade crimp terminals (for power supply)
  • Molex 47053-1000 four-pin fan headers
  • Molex 47054-1000 four-pin fan connector housing
  • Molex 08-50-0114 crimp pins for fan connector

If I do use a fan, I’d like to use a four-wire fan, with PWM input and tachometer output, though that’s overkill.  The Tiva microcontroller has plenty of timers that are suitable for generating PWM and measuring the tachometer output.

It’s easy to find four-wire fans for PCs, and it’s easy to find ball-bearing fans, but it seems remarkably difficult to find four-wire ball-bearing fans. I ordered a Qualtek two-wire ball-bearing fan, but I’m considering ordering a Delta AUB0812L-9X41 four-wire fan from Digi-Key. It uses a “Superflo bearing“, which is a permanently lubricated sleeve bearing.

The OEM fans just have the wires unterminated, so I have to add the connector. The wire colors Delta uses don’t match the colors in the Intel four-pin PWM fan specification. Also Delta specifies a preferred PWM operating frequency of 20 kHz, while the Intel spec calls for 25 kHz nominal with an acceptable range of 21-28 kHz.



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