Logarithmic attenuation

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FunkyStu

FunkyStu

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Joined 2003
#1
Hi All,

I'm currently in the process of designing a preamp using the Burr Brown PGA2310 as a volume control (with a pic and a rotary encoder).

It's amplification range goes from +31.5dB to -95.5dB (in 0.5dB steps), but I'll only be using 0db to -95.5dB part of it. This leaves me with 192 steps in total which seems to be too much.

Does anyone have an idea of how to calculate a decent logarithmic curve using say 50 or 60 steps ?

Something like this http://img.cmpnet.com/planetanalog/features/Winbond_WinPot/Fig3.jpg

Thanks, Stu.
 
#3
FunkyStu said:
Hi All,

I'm currently in the process of designing a preamp using the Burr Brown PGA2310 as a volume control (with a pic and a rotary encoder).

It's amplification range goes from +31.5dB to -95.5dB (in 0.5dB steps), but I'll only be using 0db to -95.5dB part of it. This leaves me with 192 steps in total which seems to be too much.

Does anyone have an idea of how to calculate a decent logarithmic curve using say 50 or 60 steps ?
Click to expand...

PGA2310 is already logarithmic - just use larger steps (1.5 or 2 dB) when controlling it from the microprocessor. You don't need to calculate anything 🙂

x-pro.
 
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