In a message dated 2006/10/11, tchannel@.............. writes:

> Hi Chris,    The sensor is coming along nicely.  
> Q.   The coil is done, is it a good idea to coat the coil with glue or 
> something like that just to keep the wires from getting damaged, or is it best 
> just to leave it?

 Hi Ted,

       While it should be possible to varnish the coil, I have had nothing 
but trouble with this due to turns shorting out. I suggest that you leave it 
plain, but maybe wrap a length of 'self amalgamating' rubber tape around the 
outside. This rubber just sticks to itself, nothing else. Alternatively use paper 
or a cloth tape and a water based glue (no aromatic solvents). PVC tape tends 
to 'go sticky' and peel off after a few months. You may also be able to get 
large diameter heat shrink tube, but it tends to be expensive.   

> Q.  As the wires leave the coil and travel down the shaft to the lower 
> pivot, what is the best way to make the transition off the shaft to the base?  I 
> have seen coiled wires to form a spring, to reduce drag on the movement of 
> the shaft.  I have seen large loops and small coils.  I don't know if they 
> should be hanging down or left and right. You must have tried several different 
> methods?

       I mount a couple of solder pins on the coil former and then use thin 
shielded microphone cable from the coil to the hinge (and from the upright to 
the amplifier). Tie / tape it to the arm every 6" or so. Preferably look for 
the cable variety that has a black conducting plastic shield inside the braided 
copper screen. This gives the best performance / lowest noise - otherwise just 
use thin microphone cable. 

       I use two bits of pinboard, each with 2 pins, one glued to the arm and 
one to the vertical. I use a V WIRE HAIRPINS about 2" long standing 
~vertically of 36 / 38 gauge wire. I have not tried any thicker wire. 
       You can use short coils, but you have to ensure that there are no 
turns touching.
       I use a polyurethane insulated magnet wire like Beldsol. I wrap a turn 
around the pin and then solder with a hot iron - or just solder the end 1/8" 
of wire, whichever is easier. The polyurethane insulation melts. It is easy to 
replace the wires.
       The apparatus / frame should be earthed. 

       Regards,

       Chris Chapman
In a me=
ssage dated 2006/10/11, tchannel@.............. writes:



Hi Chris,    The=
 sensor is coming along nicely.  

Q.   The coil is done, is it a good idea to coat the coil with gl=
ue or something like that just to keep the wires from getting damaged, or is=
 it best just to leave it?




 Hi Ted,



       While it should be possible to varnish=20=
the coil, I have had nothing but trouble with this due to turns shorting out=
.. I suggest that you leave it plain, but maybe wrap a length of 'self amalga=
mating' rubber tape around the outside. This rubber just sticks to itself, n=
othing else. Alternatively use paper or a cloth tape and a water based glue=20=
(no aromatic solvents). PVC tape tends to 'go sticky' and peel off after a f=
ew months. You may also be able to get large diameter heat shrink tube, but=20=
it tends to be expensive.   



Q.  As the wires leave th=
e coil and travel down the shaft to the lower pivot, what is the best way to=
 make the transition off the shaft to the base?  I have seen coiled wir=
es to form a spring, to reduce drag on the movement of the shaft.  I ha=
ve seen large loops and small coils.  I don't know if they should be ha=
nging down or left and right. You must have tried several different methods?=




       I mount a couple of solder pins on the=20=
coil former and then use thin shielded microphone cable from the coil to the=
 hinge (and from the upright to the amplifier). Tie / tape it to the arm eve=
ry 6" or so. Preferably look for the cable variety that has a black conducti=
ng plastic shield inside the braided copper screen. This gives the best perf=
ormance / lowest noise - otherwise just use thin microphone cable. 



       I use two bits of pinboard, each with 2=
 pins, one glued to the arm and one to the vertical. I use a V WIRE HAIRPINS=
 about 2" long standing ~vertically of 36 / 38 gauge wire. I have not tried=20=
any thicker wire. 

       You can use short coils, but you have t=
o ensure that there are no turns touching.

       I use a polyurethane insulated magnet w=
ire like Beldsol. I wrap a turn around the pin and then solder with a hot ir=
on - or just solder the end 1/8" of wire, whichever is easier. The polyureth=
ane insulation melts. It is easy to replace the wires.

       The apparatus / frame should be earthed=
.. 



       Regards,



       Chris Chapman