Monthly Archives: April 2019

The quest of a beacon for cats (part 2)


It’s been few month now Mio is wearing the beacon, so what can we conclude ? First part: The quest of a beacon for cats (part 1)

Battery lifetime

The CR2032 battery lasted 100 days, with 60 seconds between RF emissions. It corresponds to roughly 144’000 pulses. As the beacon transmits the battery voltage, I could log and trace the trend. However the voltage of these battery don’t drop gently at the end of their life. There is a slight slope a month before dying, but I suppose it’s better to anticipate and exchange the battery after 12 weeks of use.


Field research

Mio’s collar has a lock that opens itself if too much pull strength is applied. It appended once the collar stayed outside because Mio hang it up at a fence (or maybe it’s possible I didn’t close it correctly).

It was interesting to search it by looking at the RSSI value on the receiver. It was fun as well for my neighbors, how saw me roaming around with an antenna. In the end the necklace was lying on a fence something like 50 meters away from the house. By making circles around I could estimate the range to maximum 100 meters.

As it was rightfully pointed out to me, the beacon allows to find the collar, not the cat. But the chances Mio keeps the collar is greater than nothing at all.


I’m rather satisfied by the battery lifetime and the range, so I will probably keep this solution for a long time. We really enjoy seeing the beacon signal chart, it reassures us to know Mio is around.
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3D printed Synchrotron Magnet replica


The Cern Proton-Synchrotron (PS) is a fascinating machine. While there are many synchrotrons around the world, this one started its operation in 1959. The PS, which is nowadays part of the acceleration chain of the Large Hadron Collider (LHC), measures 628 meters of circumference. It was the first strong-focusing synchrotron (or alternating-gradient focusing), at a time when synchrotrons look like the BLN Cosmotron.

The PS main magnet units combine dipole and quadrupole magnetic functions, weight more than 30 tons and are around 4.2 meters long.

There are a 100 of these magnets along the PS ring. Some coils have been replaced, but they are still the same and the yokes are untouched.

For more details about the PS and its history, there is a complete and nicely written report available on the Cern website:

In 1959 John Adams (leader of the construction team at that time) announced the successful acceleration of protons up to 24GeV.

If you pay attention, on the picture you can spot a small scale model on the desk.

That is the target of this blog post.

2-0290.jpgThere is plenty of documentations and archives at Cern, and it was impressive to find the original mechanical drawings of the magnets. So I started Fusion360 and played with the drawings. Of course, there are yet 3D models files, but they are extremely detailed and it would shortcut the fun.

Let start with the yokes:

The magnet blocks stand:

Coils, supports and feet:

And let’s print it :

The scale is 1:20 and pictures bellow show the difference with the real thing:



The STL files are in this repository :

Thanks for reading !

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Images from Cern are free of charge for educational and informational use. The Cern term of use for audiovisual media can be find here : . This project was realized as a hobby, outside Cern.