FlightAware Discussions

RadarBox FlightStick heat stroke?

It keeps the RPi and dongle closer to the air temperature in the box.
The air in the box is also cooled better because it interfaces with all surfaces of the box.

For example you have a box temperature of 40C, then the RPi core might get to 65C without a fan.
With a fan, the RPi will only go to 50C, 10 above ambient.

As the inside box temperature is more or less fixed by the power dissipated and the surface area of the box and heat conduction to the outside, it stays more or less the same with a small fan blowing on the RPi/dongle.
Inside box temperature might also be reduced because the air move over the box surface improving heat transfer to the box material.

I think I’ll try the vent first (no fan), as a fan adds ~1W of heat (5V @0.2A) and it may add electrical noise that could interfere with the ADS-B reception.

It’s nice that the FA page will show you CPU temp alerts when the CPU temp exceeds 70’C.

I think you have a faulty stick.
I’ve had two running under my roof since the start of the year ($10 could not be resisted!). I live in the tropics and even now in the cooler wet season, the roof space runs between 35 and 40C and I haven’t had a problem yet.

i used two of the vents (they are low cost). they must be on a vertical surface or the IP rating is not correct. i mounted one down low on the front of the box and the other up high on the front

That’s really not too relevant. Especially because you can run the box much hotter with a fan while still keeping the RPi and dongles cooler.

True - it’s not 1W of actual heat, the energy is being used to turn the fan.

Any thoughts on EMI interference from the fan?

I wouldn’t be worried about that, i don’t see how a fan would produce GHz frequencies.

And compared with all the other stuff in the box, it’s unlikely to be a problem in my opinion.

Picked up a 50mm fan at lunch to experiment with.

That’s electrical energy consumed by the fan - after that, it is all converted to heat (first law of thermodynamics).

Similarly, a fan cannot cool below ambient.

Agree as @wiedehopf mentioned above, a fan would help drop the CPU temp closer to box/ambient temp. With my attic test around 40’C and my CPU around 80’C, I fan should keep it below the FA alert point of 70’C.

Adding a fan:

image

Dropped around 15 C.
(was already heatsinked)

It’s running an airspy at 20 MHz which permanently uses one core at 70 %.
The clock is set at 1.4 GHz permanently, no idle clock.
(It basically doesn’t go into idle anyway even if the function is on)

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Is underclocking an option to lower Raspi 3B CPU temps?

It doesn’t really help temperature much.

If you want to try:

Add

arm_freq=1000

to /boot/config.txt

This will still dynamically reduce clock speed if able.

(force_turbo=1 which i have enabled forces it to run at maximum set by arm_freq or default maximum if unset)

But as i said the benefits are most likely small.

Some more extensive changes:

arm_freq=900
arm_freq_min=250
core_freq_min=250
sdram_freq_min=250

over_voltage=-3
over_voltage_min=-8

Note the negative over_voltage numbers.
Running lower voltage might make the system unstable.
https://www.raspberrypi.org/forums/viewtopic.php?t=162236

You can install bcmstat and use it to check the currently used values.

Worst case you need to remove the sd-card and change config.txt on the boot partition on your main computer.
(If it doesn’t start for some reason)

Using negative settings for voltage or lower frequencies than default won’t damage anything.
So there is no harm in experimenting.

The temperature went back up, and the ‘combo’ stopped working again. The reason I say ‘combo’ this time, instead of the FlightStick, is because I cannot access the Pi. I did not noticed or checked this previously.

I’m kind of puzzled now. What are the chances that 3 SD cards, 2 Pis, and 2 power supplies having the same problem, when the other ‘combo’ 4 feet away from it has been rock solid for over 500 days?

Can the FlightStick failure also bring down the comms (WiFi)?

Similar power supplies with similiar heat problem? :slight_smile:
Might both be reducing output to prevent heat death.

I replaced the FlightStick with the RTL-SDR Blog v3. Let’s see.

How much is the price difference?
There has been so much talk and praise about v3 that I am tempted to purchse it even though I have many surplus dongles.

The price is US$21.95 shipped.

https://www.rtl-sdr.com/rtl-sdr-blog-v-3-dongles-user-guide/

It stopped working again. I’m at a loss at what could be causing the problem.

I may try a fan on the Pi, but for now, removed everything, only one ‘station’ operational.

Try swapping the power supplies to confirm they are both good.

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