I use Molex type connectors for everything. The 2.54mm (0.1”) spacing polarised connectors are available with between 2 and 16 pins and are great for connecting switch and display panels, LCD displays, sensors and even low current power (up to around 1A) connections to your PCBs. The advantage of using connectors over soldering to terminal pins is that it’s really easy to quickly disconnect the PCB and remove it from a project and it looks much neater than soldering connections directly to the board. The one thing that I always do though is solder the wires into the crimp sockets rather than crimping them, as crimping never seems to work correctly for me and they are tiny fiddly blighters.

There’s a catch… actually there are two.

The first is that they are rather expensive. You need the PCB mound plugs (available as straight or right-angle), then you need the housings for the cables and for the housing you need the small metal sockets. Molex as a brand are rather expensive and many suppliers; like Rapid Electronics in the UK have alternate sources that seem just as good but are MUCH cheaper.

The second catch is a real pain in the backside and something that I’ve just fallen foul of.

A cable I assembled had two connectors on it; one at each end. The cable connects a simple LCD display module to a project PCB. However, once everything was working I decided to change to an LCD that has a built-in backlight. Character LCDs typically have a 16 way connector which is great as that’s the largest size available in the Molex range. However, some LCDs have some strange pin numberings with pins 15 & 16 (typically used for the back light)  appearing either before pin 1, or after pin 14 on the display. Needless to say, my two displays were one of each.

Using a very small jewellers screwdriver, it’s possible to “pop” each socket out of the housing and reposition them. Unfortunately, and here’s the catch, you stand a very good chance of squashing the socket so that when it’s put back into the housing and even though it clicks home, it won’t make contact with the metal pin on the plug.

I’ve just spent several hours wondering why a working project has just suddenly stopped and it was because one of the sockets I re-positioned was slightly squashed and wasn’t making proper contact with the pin on the plug.

If you do remove the sockets, ALWAYS check the cable works afterwards.

DipTrace have released a new version of their PCB and Schematic capture software. There’s a free version available that is only limited on the number of PCB sides (two) and the number of pads. The actual board area can be almost unlimited.

I use a licenced version for all my projects as I needed the increased number of pads, but for smaller boards the free version may be suitable. The good thing is that the free version can open up files created with the licenced versions, and print them out. This means that I can include the original PCB artwork files with my projects and people can print out original PCB foils for use when making their own PCB’s.

I’ve just about completed my Evaporator project. Needless to say, there’s been a little bit of scope creep and I had to make some alterations to the final design; but there all positive I think.

It’s funny how we get spoilt by things. I can remember buying one and two line, sixteen/thirty-two character black on grey LCD displays without backlights, as there wasn’t really much other choice. I raided my parts box for an LCD display for this project and found one of these older displays. After fitting it in the prototype I realised that without the backlight, it was almost unusable; how did we ever manage without backlighting. So I changed to a four line display with back-light; as that’s all I’ve currently got available. The firmware is very simple to change for any display type so it doesn’t really matter for the end user.

Since I’m off on vacation soon, I won’t have time to write the project article text until I return (unless I can somehow slip my laptop into my luggage). Even so, it’s not going to be available for a couple of weeks.

If anybody has any ideas for projects they’d like to see, please let me know.