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+--- Thread: 118H shadowmeter resistance (/showthread.php?tid=4811)
118H shadowmeter resistance - Glenn Roberts - 05-28-2012 12:41 AM
Ok I finally got around to winding the shadowmeter coil and I can't remember and can't find what the heck the resistance is supposed to be. I think it was around 1000 Ohms, but want to be sure. Can someone please confirm this? If it is I need to pull off some wire..I'm at 1900..oops. Thanks for your help.
Glenn
RE: 118H shadowmeter resistance - 7estatdef - 05-28-2012 01:55 PM
Should be about 1.1K.
Terry
RE: 118H shadowmeter resistance - Glenn Roberts - 05-28-2012 06:07 PM
Terry,
Thanks for the confirmation. Now the bad part unwinding 800 ft of 40 ga. oh well.
Glenn
RE: 118H shadowmeter resistance - morzh - 05-28-2012 07:00 PM
I just wonder how 1K can become 1.9K, if it is wirewound. Or have I not understood?
RE: 118H shadowmeter resistance - 7estatdef - 05-28-2012 09:13 PM
If it is a real hassle you could just add a resistor across the coil to lessen it's sensitivity.
Terry
RE: 118H shadowmeter resistance - Glenn Roberts - 05-28-2012 09:59 PM
When I was winding it I was thinking "I don't think this much came off this spool, but if I'm short I really don't want to start over" I was shocked when I took a reading and it was a little over 1.9k.
Taking it off won't be too bad just want to wind it on something to save it for another project. I found a little 100 rpm gear motor that has the perfect shaft size for the coil "bobbin". What a monotonous job.
Morzh,
it's not "wirewound" as in a resistor, it is the wire wound coil for the shadow meter vane.
Here is a picture of the coil and shadow meter assembly from Chuck's website.
http://www.philcorepairbench.com/images/smrepair04.jpg
Glenn
RE: 118H shadowmeter resistance - Glenn Roberts - 06-01-2012 10:12 PM
[attachment=960]
Success!!
Question, as usual, the original was sealed in a stiff paper wrap and wax. Should I seal this in hot glue, clear nail polish...??
any other suggestions.Thanks,
Glenn
RE: 118H shadowmeter resistance - 7estatdef - 06-01-2012 10:18 PM
Nail polish has some nasty solvents in it I'd go with the hot glue or candle wax.
Terry