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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: Re: Harder than it looks posted by Dave Garretson on February 13, 2007 at 05:11:47:
One LDR is for the volume control and the other is a reference. You feed a control voltage to the op-amp which measures the voltage drop across the reference LDR and adjusts the lamp voltage to both LDRs accordingly. Provided the LDRs are in the same environment, this will compensate for temperature drift and nonlinear light response of the LDR. This should suffice even if the LDRs aren't perfectly matched.Note, LDRs are not as linear as regular resistors. The impact on sound quality is unknown.
IIRC, this idea came from Melos.
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Follow Ups
- Use a pair of LDRs and an opamp. - Istanbul Wasconstantinople 07:23:20 02/13/07 (5)
- They use LEDs - not lamps... - Allen Wright 05:12:32 02/14/07 (0)
- Re: Use a pair of LDRs and an opamp. - Dave Garretson 16:25:10 02/13/07 (3)
- Re: How about arrange the control to operate differentially? - Ralph 16:06:48 02/14/07 (2)
- Re: How about arrange the control to operate differentially? - Dave Garretson 18:15:19 02/14/07 (1)
- Re: How about arrange the control to operate differentially? - Ralph 10:24:23 02/15/07 (0)
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