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Amplifier board debugging notes (view source)
Revision as of 15:31, 13 September 2011
, 15:31, 13 September 2011no edit summary
This page contains a list of all currently known problems with the amplifier board and the solutions implemented
This page contains a list of all currently known problems with the amplifier board and the solutions implemented
= Issue List =
* check that the summing circuit is up to date
* finalize DC plane "fingers"
* settle on switch circuit design
* check voltage references
* check impedance matching, where relevant (possible on internal layers?)
* ensure sufficient bypass
= Bug List =
== Improper DC levels from voltage regulators ==
== Improper DC levels from voltage regulators ==
The adjacent diagram shows the necessary circuit. The component values are set as follows.
The adjacent diagram shows the necessary circuit. The component values are set as follows.
* Recommended values for V<sub>cc</sub> - V<sub>B4</sub> = 0.9V - {R1,R2} = {30kΩ,100kΩ}
* Recommended values for V<sub>cc</sub> - V<sub>B4</sub> = 0.9V - {R1,R2} = {30kΩ,100kΩ}
* Good value for I<sub>k</sub> is 2mA. Current through R1, R2 is negligible, as is the current going to the load (6 summers x 10uA base current) This I<sub>k</sub> ~ I, so R ~ 2kΩ (but anywhere 1-5kΩ works)
* Good value for I<sub>k</sub> is 2mA. Current through R1, R2 is negligible, as is the current going to the load (6 summers x 10uA base current) Thus I<sub>k</sub> ~ I, so R ~ 2kΩ (but anywhere 1-5kΩ works)
* 154Ω worked well for the emitter resistor (R<sub>f</sub>) on the summer input stage.
== Wrong voltage on R<sub>C</sub>/R<sub>D</sub> junction ==
== Wrong voltage on R<sub>C</sub>/R<sub>D</sub> junction ==