ml138To record a 12-lead ECG with an FE238 Octal Bio amp or ML138 Octal Bio amp the following items are required in addition to the LabChart software, PowerLab, and amplifier:. MLAC29To record a 12-lead ECG with an FE238 Octal Bio amp or ML138 Octal Bio amp the following items are required in addition to the LabChart software, PowerLab, and amplifier:. MLAC29