Are you looking for tools like Multisim SPICE LTspice Proteus or Altium? That's great! PROTO is an real time electronic circuit simulator which means you are able to setup a circuit with various components and simulate behaviour of the electronic circuit.
During simulation you can check voltages currents and many other variables. Check signals on multichannel oscilioscope and tune your circuit in real time! You can also use PROTO as logic circuit simulator and perform digital electronic analysis!

* You can report an issue or make component request at https://github.com/Proto-App/Proto-Android/issues *

Features:
+ Animations of voltage values and current flows
+ Adjusts circuit parameters (like voltage current and other)
+ Four-channel oscilloscope
+ Single play/pause button to control simulation
+ Copy electronic components
+ Learn about electronic circuits by examples in app
+ Share circuit with friends

Components:
+ DC AC Square Trinagle Sawtooth Pulse Noise voltage source
+ Current source
+ Resistor
+ Potentiometer
+ Capacitor
+ Polarized capacitor
+ Inductor
+ Transformer
+ Diode (rectifying diode LED Zener Schottky)
+ Transistor (NPN PNP N and P channel Mosfet)
+ Switches (SPST Relay)
+ Bulb
+ Operational amplifier
+ Timer 555 (NE555)
+ Digital Gates (AND NAND OR XOR NOR NXOR Inverter)
+ Voltmeter
+ Ammeter
+ Fuse
+ Photoresistor (uses phone light sensor)
+ Analog-to-digital converter (ADC)
+ Accelerometer (uses phone accelerometer sensor)
+ FM source
+ Logic Input
+ Memristor
+ Logic output

Analog Pack:
+ Tunnel diode
+ Varactor
+ NTC Thermistor
+ Center tapped transformer
+ Schmitt trigger
+ Schmitt trigger (inverting)
+ Solar cell
+ TRIAC
+ DIAC

Digital Pack:
+ Adder
+ Counter
+ Latch
+ PISO Register
+ SIPO Register
+ Seven segment decoder
+ Sequence generator
+ D Flip-flop
+ T Flip-flop
+ JK Flip-flop
+ Multiplexer
+ Demultiplexer

Misc Pack:
+ Wobbulator
+ AM Source
+ SPDT Switch
+ Digital to analog converter (DAC)
+ Antenna
+ Spark gap
+ LED Bar
+ RGB LED
+ Ohmmeter
+ Audio input
+ Microphone
+ Device battery

Sensors pack:
+ Pressure
+ Gyroscope
+ Light
+ Magnetic field
+ Proximity
+ Temperature