QAKAMP contains four bridge amplifiers with 2+ pole LP filters and differential output drivers, a high current precision voltage reference, power supply conditioning. The front end uses instrumentation amplifier with 80dB CMR extending to 100KHz.
- LM358 and OP27 opamp power wired backwards - corrected in Rev B schematic
- V- LED wired backwards in SCH, corrected in Rev B sch
- L.COM at REF- is open circuit - connected to COM
SN1 : assembly notes
- Vref built with TL1431, Rb=2.49, Ra=4.7k -> Vref = 7.2v - regulation @ +-10V
- changed Ra to 2.49k, Vref = 4.99V, regulation @ +6, -7V
- RR1,RR4 are 4.7 and 10k. Wonder if smaller values might start regulation sooner.