I'm doing my first non-kit electronics project for computer controlled fans for my electronics closet. The person who posted the project said to use JST headers. There are two four pin connectors for two Corsair LM120 fans. There doesn't appear to be a data sheet for the fans so I looked into motherboard fan connectors and found that a Molex 0470531000 is used. I'm going to build the project on a solder breadboard (meaning one where you solder the components to a breadboard like layout in case my terminology is incorrect). Given that the pitch is 2.54mm, I'm in business. The closest JST connector I could find is 2.5mm, which I've read may not work for four pins at 2.54mm, a 120 micron difference.
The other component that will be off board and connected by a cable is the HiLetgo DHT11 Temperature Humidity Sensor Module. The data sheet for the sensor gives 2.54mm pitch. I'm assuming it's the same for the board in that it easily plugs into the connector from the Corsair fan. I've found a 3 pin header on digikey.com that looks to be correct. The page links to a connector: Molex 0022012031. It doesn't look to have pins and there is a link on the page to these pins: Molex 0008510108.
Is this how one goes about building these types of connections? I have a crimp tool and don't mind making them up. The cable has to be three or four feet long so I don't imagine I could find a stock one. Is there an easier way to do this? I've searched on the web for Molex connector kits. None looked to be the for this type. Is it typical to build connection by ordering all the individual parts or is there a more generalized approach?
Best Answer
There are many things to consider when selecting a connector such as physical size, current capacity, voltage rating, number of insertion cycles, cable retention, mounting method... to name a few.
From your description, you need a 2.54mm (100mil), through-hole connector. You didn't list your current or voltage specs and it's up to you if you want a locking ramp, polarization, etc. However, this is an extremely common connector and many manufacturers, including JST and Molex, will make one that suits your needs.
You are correct that you need the board header (thing that solders into the board), metal contacts (thing you crimp onto the wire), and connector housing (piece of plastic that holds the contacts). Assuming it fits your other requirements, the Molex KK254 series should work. Take a look at their website for a better view of the connector and their recommended mating parts.
Molex KK254 Series
With regards to your selections, it looks like you selected a 3-pin housing and a 4-pin header. You can either buy the contacts and crimp them onto wire yourself or buy pre-crimped wires and splice them with your cable of choice.