Small Stone Project Notes:

Revision: 2003-03-17

The representations of the ICs on the schematic 
are drawn incorrectly, however, THE IC PIN MARKINGS ARE CORRECT for
use with this circuit.  Pin 2 is marked as the non-inverting input when 
it is actually the inverting input. Pin 3 is marked as the inverting input 
and it is actually the non-inverting input.  In other words, the plus 
and minus signs on the little op-amp symbol in each IC are swapped
around. Again, PLEASE NOTE that the pin numbers in relation to the schematic
are correct, so don't change anything in the IC component layout.


We created a reference schematic with arbitrary numbers assigned to the
components so you can easlily reference the layout against the 
schematic.  The schematic is R.G. Keen's and I claim no credit for ANY work 
on the schematic.


The decimal points are very hard to read on the schematic drawn by 
R.G. Keen. Here's what we found that initially gave us problems:

o R7  - schematic looks like a 47k value - issue J has a 4.7k value
o R11 - schematic looks like a 33k value - issue J has a 3.3k value
o R12 - schematic looks like a 47k value - issue J has a 4.7k value
o R15 - schematic looks like a 47k value - issue J has a 4.7k value
o R23 - schematic looks like a 75k value - issue J has a 7.5k value
o R42 - schematic looks like a 47k value - issue J has a 4.7k value
o My issue J has a 470ohm resistor first thing after the 9 volts input,
  the schematic doesn't have this.
o R35 - the schematic has it, my issue J doesn't have it.  The EH-4800 issue 
  of the Small Stone doesn't have this resistor either.  The unit will work fine 
  without it, here's how Jack Orman at AMZ explained it:
     Pin 6 is the emitter of the darlington buffer in the chip (IC4) and the 
     10k resistor (R35) is the ground referenced load. It will still work 
     without it because R12 will act as a load for the buffer. 

The CA3094 ICs are are obsolete but may still be available from some distributors. 

Copyright 2003  JD Sleep
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