~ Psion Emulator RIAA procedure ~ RamPak Battery replacement ~

How to work the Psion Organiser RIAA calculator

The Psion Organiser emulator above is a cut down version of 'Jape' to demonstrate my 1987 procedure for calculating component values for a lumped RIAA or similar network block with 3 time constants ~ If you have a Psion and DataLink you can download the .opk file from the Save link ~ This also contains a DICE program that is only 767bytes long

If not familiar with using a Psion XP organiser or Jape ~ Choose DATAPAK RIAA and select slot ~ Open case and turn ON ~ With cursor flashing at FIND press MODE and enter RIAA press EXE also repeat MODE and enter DICE if you wish to try it ~ Select RIAA and then t1 ~ Enter time constant for t1 then t2 and t3 ~ you can use 75e-6 or 75u for 75µs

To make entering values and displaying engineering notation clearer the RIAA program and others I wrote use my additional procedures ~ IENG to enter numbers in engineering notation 2k2 = 2200 and 4M7 = 4,700,000 etc. and ENG$ to return answers in engineering notation to specific significant figures and units ~ leading zeros like M5 give 500k

Once the 3 time constants have been set press ON to return to the menu ~ The 4 procedures R1in R3in R5in and R7in relate to 4 topologies available for 'lumped' RIAA equalisation Network as described in this pdf ~ Pressing EXE calculates the other components which can be changed at any time to see the effect on the other 3

The 2 procedures Log and Lin return the output level of an RIAA amplifier or Network in dB or V_rms respectively ~ Because these procedures calculate the output level at an entered frequency a reference frequency and the output at that frequency are required as an offset ~ Log and Lin refer only to the scale used for the output amplitude 'A' axis

For the component value calculations you should have all 3 time constants set and get a warning if they are not ~ if you make say t1 and t2 the same so they cancel you may be returned to 'Set sig figs' ~ For Log or Lin you can set the time constants to zero so (1+sτ) = 1 ~ Setting 3108µs to zero you can check a ceramic cartridge equalisation

If you leave this emulator page the procedures and settings are lost but are easy to restore ~ Using an actual organiser this does not happen because the menu is stored and the time constants are set in the calculator memory ~ The website by Jaap Scherphuis [link above] has the emulator with snapshop feature and many more DATAPAKs and info

Download a zip file with RIAA procedure source and object files

To create and save a DATAPAK image to add to this page I needed to tidy up and edit some files which I thought I had saved on a 32kB RAMPAK but when I inserted a new battery in my organiser two things happened ~ It started buzzing and ticking as soon as turned on which was cured by replacing the electrolytic capacitors

The second thing was the RAMPAK had no data because the 3V backup battery was only 0.4V ~ Typical British product that was not built to last more than 40 years and made with a battery that now appears to be unavailable but can be replaced with a CR2030/1GU as shown ~ I had the procedures on DATAPAK but doing the edits is easier with a RAMPAK plus I wanted it working again

The Panasonic CR2030/1GU has a negative tab that unlike the original and like most tabbed CR2030 batteries today is off-centre but due to the way it is fitted the tab can be bent back to be in the centre as shown ~ the tabs are also slimmer than the original Renata battery and will unsolder more easily in future ~ 2060 !

The Panasonic CR2030/1GU positive side has 2 prongs and one needs to be cut back with a Dremmel style drill with small cutting disk ~ Other tabbed CR2030s may fit and some have only one positive prong but I did not see any with a negative prong that can be so neatly bent into the centre ~ Although this battery now sits away from the PCB I still fitted the white plastic insulator ~ it's nice to know where it is if needed later

" I went to Central Station ~ To catch that early bus "