The Museum of HP Calculators

HP Forum Archive 20

[ Return to Index | Top of Index ]

41CL and the Time Module
Message #1 Posted by Gerry Schultz on 22 Feb 2012, 3:40 p.m.

I just bought a 2nd 41C Time Module from eBay (I can write that now, right?) since my first one is tied up with my 41CL. I know the Time Module uses unique hardware which makes it difficult to emulate in the 41CL.

Here's a random thought. Could Monte, if he wanted to, rework the 41CL MB such that I could take apart a Time Module and plug the circuit board directly into the CL MB? I know that's a lot of work for Monte to re-engineer the circuit board, but is this practical?


Edited: 22 Feb 2012, 3:40 p.m.

Re: 41CL and the Time Module
Message #2 Posted by Monte Dalrymple on 22 Feb 2012, 5:30 p.m.,
in response to message #1 by Gerry Schultz

You can already do this. The Time Module PCB doesn't "mount" on the 41CL board, but it will fit in the channel between the side of the case and the battery compartment. You can then solder wires from the Time Module board to the 41C bus, either on the main PCB or to the appropriate spots on the 41CL board. I seem to recall a forum message that had a photo of exactly this modification a little while ago.

I am currently working on a small PCB that can use this technique to add the timer functionality to a CL. There is room in this space for a PCB about 14mm x 40mm, which _should_ be enough room for the required circuitry. While it could _theoretically_ fit on a reworked CL board, I don't want to even attempt that. It would require changing the FPGA, CPLD and memories to BGA packages to make enough room. The design rules for the board would go from routine to state-of-the-art ($$$), with probably 6 layers ($) and blind and buried vias ($$).

I have probably invested close to a man-year on this project and don't expect to sell more than about 150 total 41CL boards. I'm only working an the Time Module clone because I have time available right now.


Re: 41CL and the Time Module
Message #3 Posted by Diego Diaz on 22 Feb 2012, 6:57 p.m.,
in response to message #2 by Monte Dalrymple


It's not just about installing the TIMER inside the CL but applying a small mod by including one capacitor and one diode to extend a bit the time allowed to replace the batteries without loosing the contents of the TIMER registers.

It does however show how the TIMER module is placed into the CL case.

Here you'll find the referred post.

Hope this helps.


PS. Just in case you don't have a use for the removed TIMER module shell and connector, I'll gladly accept them for a new life housing one of my project's modules... ;-) Contact me please.

[ Return to Index | Top of Index ]

Go back to the main exhibit hall