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Old 6th April 2004, 07:03 PM   #11
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There is now 1 of these switches available.
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Old 6th April 2004, 11:21 PM   #12
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Switches all sold. Thanks.
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Old 8th April 2004, 01:46 PM   #13
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Can anyone tell me how to aproximately (or exactly ofcourse)calculate values so that I can use this switch as a volume control.

Thanks in advance.

Regards,
Bas
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Old 8th April 2004, 07:48 PM   #14
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Post Stepped Volume Control

Quote:
Originally posted by Bas Horneman
Can anyone tell me how to aproximately (or exactly ofcourse)calculate values so that I can use this switch as a volume control.

Thanks in advance.

Regards,
Bas
Hi Bas,
Do you want to use the switch as a series ladder attenuator or as a shunt attenuator?. In the first case I have been using a graphical method on logarithmic paper.

In the latter case as I am now using I have one (only ONE) resistor in series with the signal and I switch each volume setting a different resistor to ground. So contrary to the first case the signal travels only through one resistor and there is only one resistor to ground. For the shunt attenuator the dB's attenuation are easy to calculate with dB= log V^2. Assuming a 10k series resistor I calculated for f.a. 13.5dB attenuation:
10logV^2=13.5
20logV=13.5
V= 4.7315
Then 1/V= 0.21113 as we need attenuation. The voltage is 1/4.7315 I assumed an input voltage of 1V to keep calculations simple.
R= 10k x 1/Vout /(1-1/Vout )
R =10k x 0.2113/0.7887= 2k68 or nearest standard value 2k7.
And so on, and so on....

Are you still with me?
Better I post a list of values for a 10k series resistor.
I also checked all values with a small program from Old Colony called Rescalc.
With the shunt attenuator the switch must be shorting meaning that in between two steps two resistors are switched to ground lowering the volume between detents. Suppose the switch is non shorting there will be no resistor to ground between settings and the volume would be maximum between detents giving loud bangs. I made my 47 position Shallco for 1.5 dB steps except a few of the very loudest settings giving a huge range. For the ear this pot feels as linear but of course it is logarithmic.
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Old 8th April 2004, 07:52 PM   #15
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This will be of some help.

http://www.quadesl.com/attenuator.html
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Old 8th April 2004, 08:07 PM   #16
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Quote:
Are you still with me?
Not yet

Before I check it out...would it work with this kind of attenuator?

Thanks Elso and Bill
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File Type: gif grayhill2.gif (5.1 KB, 208 views)
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Old 8th April 2004, 08:16 PM   #17
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Bas,

I think the shunt resistor should be on the output.
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Old 8th April 2004, 09:01 PM   #18
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Lightbulb Shunt Attenuator Schematic

Quote:
Originally posted by Bas Horneman


Not yet

Before I check it out...would it work with this kind of attenuator?

Thanks Elso and Bill
Hi Bas , This is the idea, though I wouldn't draw it that silly......
http://www.goldpt.com/schm_shunt.html
This is more clear. The MINI-H in the link:
http://www.goldpt.com/compare.html
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Old 8th April 2004, 09:08 PM   #19
dhaen is offline dhaen  Europe
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The switch is non-shorting, so a series attenuator as Bas drew) must be the way to go.
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Old 8th April 2004, 10:47 PM   #20
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I would rather place the shunt resistor on the output side, otherwise as it is drawn, the ground connection to the load is being interupted and switching noise is unavoidable.
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