search

alfkoehn / CO2_monitor

An open-source CO2 monitor helping to ensure a healthy environment in a class room and slowing down the spread of the corona SARS-CoV-2 virus.
https://github.com/alfkoehn/CO2_monitor
43 stars 8 forks source link

Attention fritzing part is mirrored #1

Open ARKopp opened 3 years ago

ARKopp commented 3 years ago

fritzing part is mirrored and holes are two small for 1/32 mill.

alfkoehn commented 3 years ago

Hi, thanks for your feedback but I do not think that the part is mirrored, see page 6 of the datasheet [1], or a photography of mine attached to this post.

Concerning the holes: which holes should have the 1/32 inches in diameter, the two larger ones or the 7 smaller ones (which should have a diameter of 1 mm, see [1]) and do you have a reference for that?

[1] Datasheet

SCD30

ARKopp commented 3 years ago

in the picture you soldered the pins on the wrong side. I think the SENSIRION writing should be on top and also if you do it like you did you cannot see the LED blinking. Why a led if its facing towards the PCB?

The larger holes should be a bit bigger.

Am Fr., 13. Nov. 2020 um 11:20 Uhr schrieb Alf Köhn-Seemann < notifications@github.com>:

Hi, thanks for your feedback but I do not think that the part is mirrored, see page 6 of the datasheet [1], or a photography of mine attached to this post.

Concerning the holes: which holes should have the 1/32 inches in diameter, the two larger ones or the 7 smaller ones (which should have a diameter of 1 mm, see [1]) and do you have a reference for that?

[1] Datasheet https://www.mouser.com/datasheet/2/813/Sensirion_CO2_Sensors_SCD30_Preliminary-Datasheet-1516638.pdf

[image: SCD30] https://user-images.githubusercontent.com/23075232/99057051-823b1200-259b-11eb-8bb5-f0ea3076022a.jpg

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/alfkoehn/CO2_monitor/issues/1#issuecomment-726680448, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABAXFBLWZ57VZBXBQ2JWVQTSPUB6FANCNFSM4TUKSRJA .

ARKopp commented 3 years ago

also there should be copper rings on both sides. in your version its only on on side.

alfkoehn commented 3 years ago

in the picture you soldered the pins on the wrong side. I think the SENSIRION writing should be on top and also if you do it like you did you cannot see the LED blinking. Why a led if its facing towards the PCB?

So you would prefer a drawing according to the photo attached to this post, I also thought about doing this, but since the pins were only labeled on the other side of the sensor, I decided to use this.

The argument to do it as you suggested is that this side also has the air inlets, so this is the side which should be place somewhere such that it is well exposed to the ambient air. (Note that the light you see is actually not an LED, I also thought this first, but according to my research, it rather seems to be a light bulb since this is a nice and cheap source for IR light).

The larger holes should be a bit bigger.

My starting point were the STEP files provided by the manufacturer. I might have messed something up while ex- and importing the file around, but I am curious how do you know about the dimension for the holes (sorry if this is obvious question for you) ?

SCD30_2

ARKopp commented 3 years ago

the label of the pins is on the bottom because there is no space on top. the top is definitely where the light and the opening of the sensor is. Also there a these little two pins on the botton so the sensor is not in the air.

I know the side of the holes because I have a pcb mill and when I load it into the program from Bantam Tools the holes cannot be milled with a 1/32 mill. You could also check this in DRC. Also there is almost no copper on the one side where you could solder the pin in. Screenshot 2020-11-13 13 14 44

alfkoehn commented 3 years ago

the top is definitely where the light and the opening of the sensor is.

Looking at the Datasheet document mentioned above, I think I now remember why I have chosen to draw this side: it is actually labelled as top view there. Which is a bit unfortunate, as it can indeed result in installations where the bottom side (according to the document) might be very close to some board which would be problematic for the sensor as the openings for the air, and also the temperature sensor, are located at this bottom side.

I know the side of the holes because I have a pcb mill and when I load it into the program from Bantam Tools the holes cannot be milled with a 1/32 mill. You could also check this in DRC. Also there is almost no copper on the one side where you could solder the pin in.

Sounds like I need to re-make the whole file, as I don't want people to get wrong impressions on how to install the sensor (besides from fixing the hole-diameter and the size of the copper rings). I don't have much time at the moment, but as soon as I have re-done everything, I'll push the update here.

Thanks for taking your time to make me realize that the initial fritzing file of the SCD30 is not optimal - as usual when you have two choices, the wrong one is taken ;-)

ber-red commented 3 years ago

IMHO fritzing part ist not "wrong" but one of two possibilities. As Page 2 of the Handling and Assembly Guide for SCD30 points out "...SCD30 can be mounted facing upwards or downwards."

So from my point of view: "you have two choices, one is taken, period" ;-).