Making Patch Pins



Having constructed the matrix panel itís no use without pins! These can be made using cheap plastic-bodied 2.5mm jackplugs which are widely available. We need rather slim 2.5mm plugs if they are to fit snuggly together on the panel. All the commercial plugs I found had quite large bodies and so two of them cannot be plugged into consequtive holes on the matrix. (Though I did use them for testing purposes).So I decided that I would try to make some slimmer plugs by modifying the commercially available ones. The plug body needs to be slim enough so that two can  be placed together in consequtive holes but at the same time has to accommodate a resistor which is soldered across the two poles of the jack plug. The job is not so difficult but it requires patience and some machining. I donít own a lathe..but I have a drill press..which for the light machining we need here works fine. Simply insert the plug into the jaws of the drill and use a chisel as a machine tool. Those people with access to small modelling lathes etc will find the job even easier.


 I have illustrated the steps needed to convert the jackplugs to the final pin for our patchpanel below. I think starting from scratch

It takes about 20 mins to make a complete pin.










                  Figure 1:  First take an ordinary  mono 2.5mm

                   jackplug  and remove the plastic barrel



                  Figure 2: Now carefully pull off the tip with

                  Pliers, taking care not to damage it. You can

                 then dismantle the plug as in Fig 2.  Melt a little

                solder on the flat end of the central pin.



Figure 3: Now  dismantle another jack plug and using

the tiny black insulating washer from that , reconstruct

a new plug as in fig 3, using the tip, base and central pole.

 Note the black washers at either end.






Figure 4: Now machine the base of the plug to a

 diammeter of approx 3mm.  as in Fig 4




Figure 5:  File the flat end of the central pin to

 a D-shape and then file (or drill ) a notch in the

 base, so that it can accept one of the resistor leads.

Then solder a 1% resistor (10k here) onto the plug



Figure 6: Finally to make the body of

 the pin, I machined some 5mm stock

plastic rod, and drilled a central hole

  which forms a tight fit for the plug+resistor





Figure 7:  You can use different coloured plastic stock  for different

 size resistors. I could only get hold of black or white, so

spray painting the top of the plug  is another way of colour coding.