Hello, this is my first time using pcbnew as part of a mini O-scope project. I was going to include the default BNC connector (BNC_Socket_TYCO-AMP), but I noticed that the top left pad is the same pad number as ‘2’. Shouldn’t that pad be ‘1’? Also, are there other BNC Socket modules out there?
Where is the datasheet you’re basing this footprint on at? I’d like to help, but I’m not finding that footprint in any of the default Kicad libraries.
BNC parts have a very wide price range, normally, you search for the cheapest one that meets your needs, and customize the nearest footprint you can find to that.
eg Digikey suggests Molex have the cheapest BNC 90’ Connectors
Hard to tell just from a footprint, check the data sheet.
That numbering shown, would have pin1 as the BNC centre and pin2 as the outer, with the other two larger holes also outer / GND.
(I haven’t checked the datasheet so this is a SWAG.) The two large pads labeled “2” are probably intended as mechanical mounting pins, rather than electrical connection points (Even though they are electrically connected to the connector housing . . . at least at VHF and below.) The smaller pads are probably intended to be the electrical connections to the connector. Since pad “1” is on the mechanical centerline it seems reasonable that it would be a connection to the center pin of the connector; pad “2” is offset from the centerline so it probably connects to the connector shell in some way.
Dale
I presume that this is the black plastic bodied RA BNC shown on the first page photo of http://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Catalog+Section1307191_BNC_Connectors0307pdfEnglishENG_CS_1307191_BNC_Connectors_0307.pdf1274668-1
The body pins are intended to be soldered, but are no connects.
I have used this part before and it is a fairly dire RF connector.
You could even consider a Dual Footprint, if you intend to make a few of these, with a long design life ?
eg I see Digikey have Molex 0731000105 for $1.15/100, whilst Mouser prices the 1-1337543-0, $1.10/100+ (which looks like your image), and they also show Molex 73100-0105 for $1.15/100+
A dual footprint that can accept either one of these looks possible.
Unless you need the plastic, or the panel-mount option, my choice would be the Molex one, has more solid earthing and looks stronger.
The larger pads as mounting points makes more sense. I’ve taken apart other PCBs with large connectors. I’ll have to check to see if they’re traced in the same way.
A dual footprint might just do the job. I’ll check out your suggestions. Thanks!
I’ve got a similar question about using a BNC connector, or any component really with multiple mechanical/mounting pins. Even though the mechanical pins share the same pin number (2 for the connector above), I get a DRC error if I connect a track to only one of the pins. The other is reported as un connected. For simple designs (like mine) I can work around the issue by tying the pins together, but I shouldn’t have to! Other users seem to report no need to do this.
Thanks for any advice!
RF connectors work better if there are multiple ground pins, reducing inductance.
Often the BNC connectors that only use the large pins for mechanical connection have plastic panel threads to isolate the signal ground from the chassis ground. On something like an o-scope, this is an important consideration to allow different ground references for different signal inputs.
YMMV though.
(In my designs, I usually use pin #0 for shielding or mounting pins.)