JST connector wiring - Page 1
Forum section: electronics / beginners

author: jshonw
author_rank: Contributor
timestamp: November 27, 2021, 06:12:48 am
content: Is there a polarity standard for wiring a 2 pin JST connector? Should the red positive wire be on the left with the black on the right when the key is facing forward and inserted downwards as shown below? I have seen it the other way around, so I am not sure what is more correct.

author: fabiodl
author_rank: Frequent Contributor
timestamp: November 27, 2021, 08:17:32 am
content: I do not think so. Have a lookhereMy own convention is that pin1 has always the highest voltage, and the voltage goes down as the pin number increases, up to the last pin which is always ground

author: wraper
author_rank: Unknown
timestamp: November 27, 2021, 08:29:05 am
content: There is no more correct way, and these connectors can have way more than 2 pins. Whoever claims something, it's nothing more than individual preference. However there may be reasons why you should place wires in certain order.

author: sleemanj
author_rank: Super Contributor
timestamp: November 27, 2021, 08:49:55 am
content: No defined standard, but, XH is commonly used for balance wires on multi-cell batteries.In that world, the IMAX B6 and copies are common balance chargers and so there is I think something approaching a defacto direction. If you hold the plug with the latching bits upwards, and the wire entry towards yourself, that the left most is the most positive and the rightmost the most negative.https://4.bp.blogspot.com/-4kDpF-xeoOw/WRwPvYUX-0I/AAAAAAAAjLM/yYBJp8F_YyMKFBN6OtVq-xzUOXHmUZ0RgCLcB/s1600/IMG_3352.JPGSo that would be the opposite of your picture.

author: jpanhalt
author_rank: Super Contributor
timestamp: November 27, 2021, 12:39:15 pm
content: I often wondered about that issue with 2-pin connectors and couldn't find a standard. However, there is now a de facto standard with most hobby servos for 3-pin connections. With those using a detent for female pin retention and the detent up (facing you), left is signal, center is positive, and right is ground. Early on, Airtronics/SanwaSanyoand Volz were different. Airtronics eventually switched to that standard, and Volz went mostly commercial UAV (it seems). I do not have any of its current servos to examine. The reason for having V+ in the center was to protect from destroying the servo if inserted with reverse polarity.For 2-pin connectors, I have continued to follow that order: When held with the retention barb or detent up, red/positive on the left and ground on the right. Of course, that is arbitrary with respect to the crimp. One could change their standard to orient to the crimp. With barbs, that is often opposite the crimp; whereas, with "Berg-type" detent-retained female pins, it is usually the same side as the crimp.With more than 3-pins, I give consideration to an orientation that is less likely to cause damage if inserted wrong. I usually include a key or orientation pin/blank/block.

author: tooki
author_rank: Super Contributor
timestamp: November 29, 2021, 08:56:01 pm
content: Quote from: jshonw on November 27, 2021, 06:12:48 amThere’s no standard, but my own personal approach is to put ground on pin 1, just like in your photo.FYI, in most JST connectors (by which I mean the whole brand, not just the XH connector shown), pin 1 is marked by the notch at the end of the female housing. It’s very clear on the XH connector depicted. 👍