added change log entries for U8 bypass and ADC1 & 2 series resistors to remove static...

git-svn-id: https://svn.code.sf.net/p/freetel/code@1846 01035d8c-6547-0410-b346-abe4f91aad63

diff --git a/smartmic/SM1000-C/Change-Log-C.txt b/smartmic/SM1000-C/Change-Log-C.txt
index 794ce6abf707ea06c45e600f09ed5af5d1254ffc..aad5d3bf049dc3222d42508c7f5cfa7d22452609 100644 (file)
--- a/smartmic/SM1000-C/Change-Log-C.txt
+++ b/smartmic/SM1000-C/Change-Log-C.txt
@@ -211,7 +211,7 @@ renumber to correct for duplicate #31 RGB 9/8/14
        I see your point though, change would aid assembly.\r
        Status: Will change part footprint & PCB.\r
 \r
-42.    [] added 3n9 between U8 p3 and ground \r
+42.    [] added 3.9nF between U8 p3 and ground \r
     + removed some tonal noise and \r
     Status:    No action taken - What is 3n9?  Will add.\r
     \r
@@ -293,7 +293,11 @@ Status:    Researching effect on TPS54329E SW PS chip.     RGB 09/15/14
 58. Nice tactile feeling switch for PTT\r
     (like power switch, put perhaps not locking?)\r
 \r
-59. 1nF on ADC1 and ADC2 inputs close to uC.  While debgugging noise I found big spikes and ringing when the ADCs sample.  I think it's the inability of the op-amps to drive high frequencies.  These caps removed the ringing, but made no apparant difference to the noise.  However I think they are useful as a precaution to reduce the general level of noise on the board.\r
+59. 1nF on ADC1 and ADC2 inputs close to uC.  But DNL for now. While debgugging noise I found big spikes and ringing when the ADCs sample.  I think it's the inability of the op-amps to drive high frequencies.  These caps removed the ringing, but made no apparant difference to the noise.  However I think they are useful as a precaution to reduce the general level of noise on the board.\r
+\r
+60. 1500 resistor between ADC1 and ADC2 and outputs from op-amps.  After much experimentation these were found to reduce the static type clicks being produced by ADC to acceptable levels.\r
+\r
+61. LM386 power supply bypassing to remove switcher "washing macine" type noise from ouput audio.  4.7 ohm (rated at 200mA, IIR=0.2W) between VIN and pin 6 U8.  220uF electrolytic between pin 6 and GND.  Both placed near U8.\r
 \r
 Questions:\r
 1.  SM1000 designed to be operated with 6-16V power supply. Would should recommend 9-15V. Should we recommend PS? Many will operate at 13.8V(rig supply). Do we risk ground loops, etc. using rig supply?\r