MaxESP3 footprints


Hi all,

I ordered a bag of bag of RJ12 connectors with the intent to build a few sets of the MaxESP3 and the smart hand controller, however they don't fit the footprint on the PCB.

Naively, I thought that RJ12 connectors were more or less the same, but the pin orientation is reversed and the pitch does not match.

Is there a detailed BOM somewhere? The one on EasyEDA is missing details on the exact parts. This would be enormously helpful.

George Cushing

Sounds like you have RJ12s that are designed for fitting under the PCB. I bought a box of 500 for $10 a few years ago and used them in projects. Wasn't until I tried to use them on a OnStep PCB that I realized they were for under board fitting. You have to look at the ad photos carefully to determent the pin layout unless using the EasyEda BOM part numbers. Here's what you want 6p6C RJ12 phone 90 degrees. About $0.10 a unit by the 100.


Hi George,

Thank you for your reply, it is much appreciated. And good info for the next guy.


Hi again George,

I have just measured the connectors I have purchased that do not fit. They are the same as the ones linked to in your Aliexpress link.

And they do not fit for ST4 footprint. Neither the pin pitch and orientation nor the distance to the mounting holes match.

The drawing above shows 6 mm from the back to the middle of the mounting hole. The footprint is ~10 mm from back to middle of the hole.

George Cushing

Seems everyone in China is selling these. Most are mirror of the standard mounting (Type 2) and the positioning lugs are not the proper distance from the pins for OnStep PCBs. 

The Adam Tech MTJ-669X1 looks good. So do their MTJ-660X1 and MTJ-66GX1. In larger lots Arrow's prices are close to those of Chinese. They are still better than DigiKey or Mouser in small orders.