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@ How to measure voltage?
- High Resistance + Ammeter
- Null detector
- Oscilloscope : cathode ray tube
- Digital Voltmeter (ADC - integrator)
- Wikipedia: Voltmeter
@ How to measure current?
@ What is transistor?
- BJTs (Bipolar junction transistors) - current
base/emitter junction + base/collector junction
(current BE -> output current BC) exponential dependence : Ice ∝ KVbe
- FETs (Field effect transistors) - voltage
source + gate + drain + body(substrate)
(voltage between source & gate -> current of drain & source) : Ids ∝ Vgs^2
Junction FET(JFET)
insulated gate FET (IGFET) - metal oxide semiconductor FET (MOSFET)
- Usage: 1. Switches 2. Amplifiers
- Wikipedia: Transistor
@ What is opamp?
- for mathematical operations (addition + subtraction + integration + differentiation)
V_out = (V_+ - V_-) G_openloop
- Two Golden Rules:
1. No current will flow into the inputs.
2. The input voltages will be nearly equal.
- Wikipedia: Opamp
@ Weston Cell
- wet-chemical cell that produce highly stable voltage
- cathode: amalgam of cadmium and mercury
anode: mercury
electrolyte: solution of cadmium sulphate
- Wikipedia: Weston Cell
@ ADC : Analog-to-digital converter
- Direct conversion ADC or flash ADC - comparator + logic circuit
- Successive-approximation ADC - binary search
- delta-encoded ADC - counter + DAC + feedback
- Ramp-compare ADC (integrating, dual-slope, multi-slope ADC) - saw-tooth signal
- Wikipedia: Analog-to-digital_converter