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LM317, understanding and listening - July 2007
Last revision on July 2007

LM317, understanding and listening

Noise figure on LM317 output. See article for details.


Figure 1

Noise figure 1

Cadj = 10µF tantalum, Cout = 1µF MKT.
2mV/div.
Only see noise from measurement method. Real noise is certainly less. No subjective noise, even putting ear near speaker.



Figure 2

Noise figure 2

Cadj = 10µF tantalum, no Cout.
2mV/div.



Figure 3

Noise figure 3

No Cadj, Cout = 1µF MKT.
2mV/div.
Noisy (shuffle) at listening place.



Figure 4

Noise figure 4

No Cadj, no Cout.
2mV/div
Subjectively noisier than figure 3. (16mV pp noise).



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