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ggetchell
USA
3 Posts |
 Posted - 05/15/2014 : 16:55:20
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| Would it be necessary to add a 10MegOhm resistor to the anode lead for this particular tube or is the circuit enough for it, as per the specs for the 712 it specifies a 10 meg ohm resistor on the anode end. |
Gregory P. Getchell |
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| Reply #1
ZLM
1271 Posts |
Posted - 05/20/2014 : 15:40:55
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The GMC-080 has default3M ohm resistor.
If your tube needs 10M ohm, then you can add 7M ohm.
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| Reply #2
ComicReader
USA
3 Posts |
Posted - 04/11/2015 : 21:18:40
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quote:
Originally posted by ZLM
The GMC-080 has default3M ohm resistor.
If your tube needs 10M ohm, then you can add 7M ohm.
I could not find any 7M Ohm resistors, and this is all very new to me. I found some 10 Meg Ohm 1/2 Watt 5% Carbon Film Resistors, will those work? Or do I need to use 7M Ohm exactly? |
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| Reply #3
ComicReader
USA
3 Posts |
Posted - 04/11/2015 : 21:22:52
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Image Insert:
18.06 KB
Here is a picture of what the 10 Meg Ohm 1/2 Watt 5% Carbon Film Resistor looks like. |
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| Reply #4
ZLM
1271 Posts |
Posted - 04/20/2015 : 06:51:15
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| This works. |
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| Reply #5
ComicReader
USA
3 Posts |
Posted - 04/23/2015 : 02:43:39
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| But wont it create too much resistance when the internal 3Meg Ohm and this 10Meg Ohm combine? How does the 1/2 watt translate into the needed resistance? |
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| Reply #6
Alchemy2
Canada
89 Posts |
Posted - 04/23/2015 : 13:05:30
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The watt rating has to do with the power the resistor can handle. With high voltages, you're running very low current, in the microamp regime, so even at 400-500V,
V*V/R = power, so 500*500/10000000 = 0.025W; your resistor is rated at 0,5W = plenty! No worries. Even a 1/4W resistor is fine
PS - if you want your total resistance to be exactly 10M, then take two of you 10Ms and connect them in parallel, and add 2M more. 2x 1M in series will work. Alternately, you could take 2x10M in parallel, and serially add 4x10M in parallel, and that gives you a total of ~5M + 2.5M = 7.5M. close to the 10M when added in line with the 3M on board the unit. You could also instead take 3x10M in parallel, and add serially another 3x10M in parallel, to yield 6.66M. When added to the 3M, that is 9.67M, which is probably close enough to 10M albeit slightly lower.
If you are not comfortable with resistance and electronics, look up ohms law on Wikipedia to familiarize yourself. Good luck! |
The more I learn, the more I realize I do not know! |
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GMC 080 and LND712 tube
