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Best Function Generators Under $100 (2026)

We selected products under $100 with the highest value score based on user ratings, supported signal types (4–20mA, voltage ranges, PWM/frequency), and suitability for PLC or general test use

This roundup covers compact function and signal generators that prioritize instrumentation features valuable to technicians and hobbyists while staying under $100. Selections were ranked by a value score that balances price, user ratings, signal types (4–20mA, voltage outputs, PWM, frequency control) and practical testing relevance for PLC and general-purpose signal work

Top Picks

  1. 1
    DROK 4-20mA/0-10V Dual Signal Generator (2 pcs)

    DROK 4-20mA/0-10V Dual Signal Generator (2 pcs)

    DROK • ★ 3.9/5 • Mid-Range

    Dual signal generator module outputs 0/4-20mA current and 0-10V voltage with a clear LED display. Useful for PLC testing and troubleshooting; praised for accuracy and ease of use, though build quality and power sourcing receive mixed feedback

    • dual amp & volt output
    • bright LED display
    • back calibration potentiometers
    Check current price on Amazon →
  2. 2
  3. 3
    Healflux Custom Frequency Generator V2

    Healflux Custom Frequency Generator V2

    Tartpe • ★ 3.5/5 • Mid-Range

    A compact frequency generator offering adjustable 0.01 Hz to 20 kHz for Schumann resonance-inspired tones. Aims to enhance relaxation and sleep quality. Customer note: 5.0 rating based on a single review

    • adjustable 0.01 Hz–20 kHz
    • Schumann resonance concept
    • compact personal device
    Check current price on Amazon →
  4. 4
    Riiai 4-20mA / 0-24V Current Signal Generator

    Riiai 4-20mA / 0-24V Current Signal Generator

    Riiai • ★ 3.3/5 • Mid-Range

    Riiai signal generator converts 4-20mA to various modes (mA, V, XMT) with adjustable precision. Real-time curve and USB rechargeable, suitable for PLC testing. One customer notes good usability, while another cites accuracy and resistance measurement limits

    • multi-signal-type support
    • precise 0.01mA/0.01V resolution
    • USB rechargeable with presets
    Check current price on Amazon →

Buying Guide

Match signal types to your application

Choose units that output the signals you need: 4–20mA for industrial loop testing, 0–10/12/24V for voltage-signal simulation, or dedicated frequency outputs for waveform work

Check output ranges and resolution

Confirm a generator's minimum/maximum output and step resolution so it can simulate your device under test accurately across the full operating range

Prefer adjustable/current-mode for PLC testing

Adjustable 4–20mA models are more useful for PLC and transmitter calibration because they reproduce industrial current-loop behavior directly

Consider interface and control options

Look for easy front-panel controls or simple PWM/frequency adjustment if you need quick changes in the field rather than complex software setups

Evaluate build quality and electrical safety

Choose devices with solid connectors, clear labeling, and appropriate isolation or protection to reduce risk when connecting to live control systems