Hardware Option

I’m trying to work out what I need - have a few questions.
I want the 4 and am considering the heat sink and cooling fan case. But it looks like the fans use the pins at the end. This would conflict with a MMDVM hat (jumbo spot) which looks like it needs the pins at each end with 2 ten pin connectors. How do people put this together? Do I need to keep them separate? I thought I could plug the hat on the top but not with cooling as well it appears? Or do I have to install the hat then draw power off the back of hat for the fans?
If I don’t cool it, does the standard raspberry case have enough space for a HAT card? It looks like it does but I see no examples. Thanks

Hi alanmcd,

I wasn’t able to find the MMDVM HAT from our website, but is this the HAT you are talking about? https://www.tindie.com/products/dave31418/mmdvm_hs_hat-rev-15-simplex/#product-description

In the image, it does show that ten pins are used, six on one end and four on the other end for both rows. Yes, I can confirm that the dual fan component of the Armour Case for Raspberry Pi 4 requires a connection to 5V (red) and GND (black). We have a guide showing how to assemble the case and connect the fans to the Pi 4, here: https://www.littlebird.com.au/a/how-to/221/armour-case-with-dual-cooling-fan-for-raspberry-pi-4

Though I don’t have a MMDVM HAT to test with the case, perhaps one solution if you’d like to plug the HAT on top of the Pi 4 + Case (without connecting the fans), is to use some stackable female 2x20 pin headers.


Thanks for the reply Cherie,
The HAT you show is similar to the one I was after - thanks.
But I’ve seen photos of the fan power being connected to the other 4 pin jack (not not he 40pin connector. Is this possible? Or a mistake? If this is possible it provides for installing the HAT over the armour case and fans as you suggest.

Hi Alan,

No problem!

Just to clarify, which 4-pin jack is this? Do you happen to have a reference image of it?

Alternatively, as the 5V power rails may be used to power multiple devices, you could (provided you don’t use more current than is being supplied) connect wires to the wires from the dual fan, and connect this to 5V and GND on the back of the Raspberry Pi 4. Then install the HAT with stackable 2x20 female headers.


Is this possible

The J14 pins seem to be power as well

Hi Alan,

Thanks for the references. Ah, that 4-pin header allows you to power the system using an ethernet cable with a PoE HAT: https://www.raspberrypi.org/blog/introducing-power-over-ethernet-poe-hat/

Under the part where it says ‘PoE header’ it only states TR_TAP in the schematics for the Raspberry Pi 4. I am unable to see any reference to ‘GND’ or ‘5V’ there : https://www.raspberrypi.org/documentation/hardware/raspberrypi/schematics/rpi_SCH_4b_4p0_reduced.pdf

I have just tested it with the fans as well, and no it doesn’t seem to work that way.


Thanks - OK so If I want the fans AND the HAT, I need to ensure I’m not demanding too much power. It seems that once you connect the fans you cannot use the 40 pins for anything else (e.g. a ribbon connector). I assume you mean to solder the power onto the underside of the pins on the raspberry?

Yes, while i’ve not tested it out as I don’t have the MMDVM HAT, it might be worth a shot to try connecting the fan to the underside of the pins on the Raspberry Pi as long as you don’t use more current for your project than is supplied. : )

Thank you so much for the info - much appreciated

You’re Welcome

  • Team Little Bird