The Museum of HP Calculators

HP Forum Archive 12

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HP-45 and crystal add
Message #1 Posted by Michel Beaulieu on 18 Apr 2003, 7:36 p.m.

I read on the museum page of the HP-45 that we can add a crystal to the calculator to incrase the timer accuracy. The crystal is a 784KHz. The problem is that i can't find anywhere this value; is it really a 784 KHz? Where to find one?

Thanks Michel

      
Re: HP-45 and crystal add
Message #2 Posted by Erik Wahlin on 20 Apr 2003, 1:22 a.m.,
in response to message #1 by Michel Beaulieu

I believe that the only place you are going to find one is to use the crystal from an HP-55. I tried looking for a crystal once for a 55 and could not find anyone that makes it.

            
Maybe a X-tal with a divider...
Message #3 Posted by Vieira, Luiz C. (Brazil) on 20 Apr 2003, 3:37 a.m.,
in response to message #2 by Erik Wahlin

Hi Michel, folks;

I do not know if at least one of the connections for the X-tal in the HP45 circuit accepts direct waveform. If so, you can try a multiple (×8, ×10, ×12, etc.) and use a divider. I think there's plenty of space inside the HP45 case so you can add a small PCB with the (MOS) oscilator + divider and connect it to the mainboard.

Just a suggestion.

Luiz C. Vieira - Brèsil

            
Re: HP-45 and crystal add
Message #4 Posted by David Smith on 20 Apr 2003, 9:08 p.m.,
in response to message #2 by Erik Wahlin

Try International Crystal in Oklahoma City. They can make just about anything for a somewhat reasonable price. In the before time I had a couple hundred of the crystals. Sold them along with the instructions on how to modify the HP45. Wish I had more...

                  
Re: HP-45 and crystal add
Message #5 Posted by Vieira, Luiz C. (Brazil) on 20 Apr 2003, 9:25 p.m.,
in response to message #4 by David Smith

Hi;

maybe they also have special prices for big quantities. I have an HP55 and I know crystals may degradate (mechanical joints, mostly) after some time. I'd like having a couple of them, for safety.

If Michel is contacting them, I think others in here would like to order these crystals, too. What about joining efforts and order a bunch of them for a significant reduction in price?

Just a suggestion.

Luiz C. Vieira - Brazil

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