PLC Simulator

Electronics fundamentals for industrial controls and sensors

The electronics inside sensors, I/O cards and controllers: parts, switching, signals and fault finding, with a small circuit explorer.

12 units
3 free
3.2 hours
Start free: Resistors, capacitors and inductorsSee plans

Training material. Follow your site procedures, local electrical code and the manufacturer's instructions. Lockout/tagout and a qualified person are required for real equipment.

What you will be able to do

  • Read a resistor colour code and size an LED current-limiting resistor, including its power rating.
  • Switch a 12 V lamp or relay coil from a logic output with a transistor and a correctly sized base resistor.
  • Explain high, low and the forbidden zone, and why PLC field inputs use 24 V.
  • Scale a sensor signal with an op-amp or a 4-20 mA loop and a divider, and smooth it with an RC filter.
  • Read a datasheet for absolute maximum versus recommended values and the five numbers that matter first.
  • Trace a noise problem to its source and apply separation, shielded twisted pair and single-point grounding.

  1. 01

    Resistors, capacitors and inductors

    Free16 min · lesson

    Decode a resistor colour code, watch a capacitor charge through a resistor, learn why a coil resists changes in current, and set an LED current in a graded circuit.

  2. 02

    Diodes and LEDs

    Free15 min · lesson

    Treat the diode as a one-way valve, size and power-check an LED resistor with a calculator, and see where the flyback diode goes.

  3. 03

    Transistors as switches

    Free18 min · lesson

    Switch a 12 V lamp or relay coil from a weak logic output, compare NPN, PNP and MOSFET switching, and pass a graded switch-the-lamp challenge.

  4. 04

    Logic levels and digital signals

    Pro14 min · lesson

    Test which output can drive which input across 3.3 V, 5 V and 24 V, learn why industrial inputs are 24 V, and fix a floating input with a pull-up.

  5. 05

    Analog signals and op-amps

    Pro17 min · lesson

    Scale a small sensor voltage with a non-inverting amplifier, buffer a weak source with a follower, and spot output clipping at the supply.

  6. 06

    From sensor to signal

    Pro16 min · lesson

    Follow a pressure reading onto a 4-20 mA loop and a 1-5 V input, scale with a divider that allows for its load, and filter noise with an RC pair.

  7. 07

    Power supplies

    Pro15 min · lesson

    Compare the heat of linear and switching regulators on the same job, estimate ripple, and see why industrial controls use 24 V DC.

  8. 08

    Reading datasheets

    Pro14 min · lesson

    Tell damage limits from design limits, find the five numbers that decide a part fits, and click the right row on a sample datasheet.

  9. 09

    Noise, grounding and shielding

    Pro15 min · lesson

    Trace where noise starts and how it couples in, apply twisted pair, shielding and single-point grounding, and match problems to fixes.

  10. 10

    CircuitPlayground: build, check, learn

    Pro20 min · lesson

    Do nodal analysis by hand, then build and check six graded circuits in a tap-to-place explorer that is a training model, not a SPICE simulator.

  11. 11

    PCB and soldering basics

    Pro14 min · lesson

    Learn what a circuit board is, compare through-hole and surface-mount, order the stages of a good joint, and review soldering safety.

  12. 12

    Electronics troubleshooting

    Pro18 min · lesson

    Find a dark-LED fault from voltage readings and divide-and-conquer, then answer a graded set mapping symptoms to causes.

Who this track is for

Technicians, apprentices and controls engineers who work with PLCs and field devices and want to understand the electronics behind them. Ohm's law, meters and relays are covered in Electrical Foundations.

3 of the 12 units are free with a free account, with no card and no expiry. The other 9 are part of a paid plan; compare them on the pricing page.

Related tracks

What electronics do I need for industrial automation?

The essentials are Ohm law, how a diode and a transistor act as switches, how a power supply is regulated, and how sensors produce voltage, current or switched outputs. That is enough to understand why a 24 V input card reads what it reads.

What is the difference between NPN and PNP sensor outputs?

A PNP output switches the positive supply to the load, which is called sourcing. An NPN output switches the load to the negative supply, called sinking. The input card must match the sensor type, or the signal will never register.

Do I need electronics before learning PLCs?

You can start PLC programming without it, but electronics explains the hardware side of every input and output, which is where many commissioning faults hide.

How much of Electronics Foundations is free?

3 of the 12 units are free with a free account, no credit card and no expiry, starting with Resistors, capacitors and inductors. The remaining 9 units are included with a paid plan; see the pricing page for the current plans.

Do I need a PLC or any hardware?

No. Everything runs in the browser against simulated equipment. It is training material: it does not replace supervised practice on real equipment, and lockout/tagout and a qualified person are required for real equipment.

Start with the free units

Browser-based, no install, no hardware.

Start free: Resistors, capacitors and inductors