CapAAVSO@....... writes:

>     Danie and I have used various pens; ball point, felt tip, draftsmen's 
>  drawing pens and syphon pens but they all have a bad habit of quitting and 
>  leaving a blank recording now and then. 

    I have found "Roller Ball" pens to be quite satisfactory on paper. To 
keep the mass / size down, use just the "refill" tubes, not the whole pen.

    Designs for drum / chart recorders have been published in Practical 
Electronics.

    To make a drum, it may be easier to buy plastic tube and then fit plywood 
end disks.

    You can use a dot matrix printer with fanfold paper as a multi channel 
chart recorder.

    I do sometimes use smoked paper and a fine scriber. It gives a very fine 
and precise trace, but it can be a bit messy if something goes wrong. You 
"fix" the trace with hair lacquer. 

    Chris
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