List of Board Changes

Here is a list of changes made to the boards received from Sierra Circuits.

= Board 1 =


 * Individual channel 14 was missing C2. We placed the component on ourselves.
 * There was a wrong resistor where the 100k resistor should be. This was replaced.
 * Changed the 35.7k resistor in the voltage reference to 130k in order to increase the current on each transistor leg.
 * The voltage regulator for AMPREF had the wrong pin out in our drawings. We rotated it so that VCC_VRef moved to where AMPREF was and a wire attaches from AMPREF to where VCC_VRef was.
 * This board has been populated by SiPMs.
 * For channel 8
 * The 25 micron SiPM has been changed to a 50 micron SiPM
 * C3 has been replaced by a 47nF capacitor from a 10nF. The RC time between C3 and R1 is the source of the low frequency "bump" in the gain.
 * R2 has been increased to a 3.3k resistor. This is to lower the gain of the circuit to compensate for the higher gain from the 50 micron SiPM.
 * R3 has been increased to a 1.1k resistor. This is to lower the gain of the circuit to compensate for the higher gain from the 50 micron SiPM.
 * R4 has been increased to a 1.5k resistor. This is to lower the gain of the circuit to compensate for the higher gain from the 50 micron SiPM.
 * Added R21 of 365 Ohms in parallel with R2.
 * Added C21 of 10nF in parallel with R2 and in series with R21. C21 and R21 were added to shift the frequency "bump" in the gain at low frequencies due to the increased values of R2, R3 and R4.

= Board 2 =


 * Individual channel 15 had 2 RBi's instead of an RBi and a CBi. We replaced the wrong RBi with the correct CBi.
 * The 100k resistor in the summer part of the voltage reference was actually a 442k resistor.
 * The voltage regulator for AMPREF had the wrong pin out in our drawings. We rotated it so that VCC_VRef moved to where AMPREF was and a wire attaches from AMPREF to where VCC_VRef was.
 * Changed the 35.7k resistor in the voltage reference to 130k in order to increase the current on each transistor leg.

= Board 3 =


 * Individual channels 11 and 15 had 2 RBi's instead of an RBi and a CBi. We replaced the wrong RBi with the correct CBi.
 * The 100k resistor in the summer part of the voltage reference was actually a 442k resistor.
 * The voltage regulator for AMPREF had the wrong pin out in our drawings. We rotated it so that VCC_VRef moved to where AMPREF was and a wire attaches from AMPREF to where VCC_VRef was.
 * Changed the 35.7k resistor in the voltage reference to 130k in order to increase the current on each transistor leg.
 * Changed C2 from 10nF to 1nF (this was later changed back to 10nF)
 * This board has been populated by SiPMs.