Fig. 2 in Scientific note A portable bio-amplifier for electric fish research: design and construction

Fig. 2. External (a) and internal (b) views of the bio-amplifier. a: 1, dipole input; 2, power switch; 3, power LED; 4, BNC output to oscilloscope/digitizer; 5, earphone jack; 6, fine gain control; 7, covered ground stub; 8, coarse gain switch; 9, dipole reversal switch; 10, earphone volume control. b: 1, battery bay (rechargeable batteries removed); 2, battery terminals; 3, circuit board; 4, operational amplifier; 5, resistor; 6, trimmer potentiometer; 7, mount to bracket; 8, electrolytic capacitor; 9, ceramic disk capacitor; 10, 4pF ceramic disk capacitor across R20 as optional high-frequency attenuator.