Hi all
I've read all the threads I can find on the LM1875 and seen all the great layouts that have been produced but there seem to be some big variances in component values which I don't understand. I'd really appreciate views and advice.
The layout attached is as per the datasheet with the exception of RX which some posters have included. So :
RX - some have included 1K - why?
R1 - standard at 1M - some omit - why?
C1 - ranges between 1u and 2.2u - what are the pros and cons?
R2 - standard at 22K
C4, C3 - standard at 0.1uF
C6, C7 - ranges between 100 and 220uF. Use lower values with a higher VA transformer assuming it has adequate smoothing?
R4 and R3 - set the gain but some use high values (180K,22K) whereas the datasheet shows 20K and 1K - pros and cons?
C2 - most seem to stay around 22uF, I assume a bipolar is best? If I went to say 47uF what would be the effect?
R5, C5 - the Zobel network to stop capacitive loads creating high frequency oscillations - any reason to change 1R and .22uF?
Thanks in anticipation
Peter
I've read all the threads I can find on the LM1875 and seen all the great layouts that have been produced but there seem to be some big variances in component values which I don't understand. I'd really appreciate views and advice.
The layout attached is as per the datasheet with the exception of RX which some posters have included. So :
RX - some have included 1K - why?
R1 - standard at 1M - some omit - why?
C1 - ranges between 1u and 2.2u - what are the pros and cons?
R2 - standard at 22K
C4, C3 - standard at 0.1uF
C6, C7 - ranges between 100 and 220uF. Use lower values with a higher VA transformer assuming it has adequate smoothing?
R4 and R3 - set the gain but some use high values (180K,22K) whereas the datasheet shows 20K and 1K - pros and cons?
C2 - most seem to stay around 22uF, I assume a bipolar is best? If I went to say 47uF what would be the effect?
R5, C5 - the Zobel network to stop capacitive loads creating high frequency oscillations - any reason to change 1R and .22uF?
Thanks in anticipation
Peter