General > General Technical Chat
Connector for slightly bigger wire than will fit in JST SM
davethomaspilot:
The insulation on the wires is too big to fit in the JST SM contacts.
Wire size (insulation) is 2 mm diameter. It just won't fit.
First, does it really matter? Crimps seem really strong--I can't pull the wire out of the crimp.
If it does, can some one recommend a slightly larger connector that's easy to crimp? 1.5 amps, low voltage rating.
Just two wires--application is for adding a crimp connector to the 12V side of a 12V to 5V DC/DC.
thm_w:
Does it matter for hobby use? no.
What AWG wire, you don't have anything thinner? The SM contact is rated 28-22 AWG.
https://www.jst.com/wp-content/uploads/2021/03/eSM.pdf
davethomaspilot:
Don't know wire gauge, except it's about .95 mm diameter. 19 or 20 AWG. Can't change it--the DC/DC convertors I have on hand have the wires.
Not quite hobby--I'm making 10 assemblies that cost around $1K each. They will be used only once or twice a year, but will be expected to last at least 10 years.
The crimp on the wire is really good--it's just that the insulation won't fit under the outer crimp. Thinking about it, I wouldn't think the extra mechanical strength provided by getting the insulation under the crimp would be significant compared to the actual wire. But, I know a "good" crimp requires the insulation to be in the crimp.
Found these on Amazon and will give them a try:
https://www.amazon.com/Molex-Micro-Fit-Circuits-receptacle-Terminal/dp/B078PZY6SM/ref=sr_1_2?qid=1681422924&refinements=p_n_feature_four_browse-bin%3A18945778011&s=industrial&sr=1-2
Thanks!
davethomaspilot:
The maximum insulation thickness for the ones in that link is 1.8 mm--same as the SM that I've used.
Outside diameter is 2 mm.
I actually shaved some insulation off the wires and got a pair of wires to fit. But, that's too much hassle and I still don't think it adds significant mechanical strength compared to something like 20 AWG wire. But, opinions welcome!
thm_w:
If this is for a high end product, then yeah just get an appropriate connector that is rated for ~19 AWG wire.
Mini fit jr. can be 18-24 AWG
Micro fit contacts you linked are 20-24 AWG so might work.
Probably this https://www.molex.com/pdm_docs/ps/PS-44300-001.pdf
Spec states max outside insulation diameter 1.85mm
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