Posts: 774
Threads: 93
Joined: Aug 2005
Hi again,
Please note that you'll need a changeover reed, as well as a convenient place to hold the activating magnet... In HP-41's this is the way I went, using the PORT-1 cover to hold the magnet... but HP-41 only needs a simple "Open/Close" reed to switch between speeds. Actually I choose the serial capacitor approach to build my 41 speed-up.
I simply hate drilling, cutting, or otherwise "damaging" the housing of one of these bauties... so I go the "Hidden Switch" way for my 42 upgrade.
Just a paper clip tip is enough... even the edge of the IR cover can be used to move the switch up and down.
Here you are the pics:
![](http://www.hpmuseum.org/guest/ddiaz/dibujo.jpg)
![](http://www.hpmuseum.org/guest/ddiaz/dibujo2.jpg)
Hope this be useful.
Regards.
Diego.