Last year I got a Jornada 720 off ebay. I’m new to HPC:Factor, but previously saw the great thread by Citgo
(posted 14th Jan 2023
) for making a DIY docking station for a Jornada 690.
My 720 did not come with anything
(apart from its battery, which was dead and so I had to re-cell it
) and as sync cables
(and docking stations
) are rare/expensive then I decided to make my own dock, using mostly materials that I had lying around.
My aim was to get a basic serial Terminal connection
(using a 9 way D type socket on my docking station
) talking between the 720 and a Windows 10 desktop.
I hope members will find this exercise of interest, so am detailing it here. I’ve attached photos showing its construction.
The key component for me was to get some “Pogo” spring loaded pins, 9.5mm long worked ok, off Amazon UK.
The spacing of the 10 contacts
(2 rows x 5 contacts
) underneath the 720 is slightly larger than the usual 0.1” spacing of printed circuit boards
(of the type in the photos below
). However I found that by rotating a small piece of circuit board by 45 degrees
(see photo
) then the spacing does nicely match the underside of the 720.
As I mentioned, I was just after a basic serial connection, so just needed to use 3 of the 10 underside connections. These were as follows :-
1
)
(Yellow cable
) ”Pogo” Pin 7 to Pin 2 of 9 way “D” type
2
)
(Red cable
) “Pogo” Pin 4 to Pin 3 of 9 way “D” type
3
)
(Black cable
) “Pogo” Pin 5 to Pin 5 of 9 way “D” type
The springy “Pogo” pins make a good connection with the underside, but I needed some way of gently securing the 720 on top. I came up with this very “Heath Robinson” way of using cable ties, which flex to allow the 720 to be positioned – but then the heads of the ties gently hold and push down to keep the 720 in place. I used a cut down plastic hook and a cable tie securing pad to hold the ties in place
(and a small amount of superglue once the cable ties were in the correct position
).
The only real downside of this
(odd!
) cable tie method of securing the 720 is that the screen cannot be fully closed when the 720 is in place on the dock
(due to the heads of the cable ties, which hold the 720 in place
).
I have also considered adding a USB socket
(type B with 4 connections
), cabled to 4 of the “Pogo” pins. However I am not sure a simple connection will
(safely
) work due to differing voltage levels of RS232 vs USB. It may be that the circuit board of a real HP dock does some voltage level adjustment
(but I am not sure
).
(720 on dock.jpg)
(top of dock.jpg)
(dock connector.jpg)
(underside of dock.jpg)Attachments
----------------
720 on dock.jpg (156KB - 0 downloads) top of dock.jpg (308KB - 0 downloads) dock connector.jpg (66KB - 0 downloads) underside of dock.jpg (470KB - 0 downloads)
I had no idea you could get the pins that easily! 