Best Function Generators Under $100 (2026)
We ranked products under $100 by a value score combining output capabilities (current/voltage/frequency), build/connectivity, and real-world utility for PLC and bench testing
The Verdict
- Best Overall: DROK 4-20mA/0-10V Dual Signal Generator (2 pcs) — Best for PLC diagnostics: offers dual current and voltage outputs useful for simulating sensor signals and looping tests
- Best Value: Adjustable signal generator 4-20mA 0-12V DC for PLC testing — Best for precise loop testing: compact adjustable 4–20 mA and 0–12 V outputs ideal for focused PLC signal checks
This roundup covers compact function and signal generators suitable for workshop, PLC testing, and basic waveform work, focused on units under $100 chosen for utility and value. Picks were selected by comparing core features (current/voltage outputs, frequency range, and output modes) and overall value score for small-scale industrial and hobby use
Top Picks
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1
Best Overall DROK 4-20mA/0-10V Dual Signal Generator (2 pcs)
Best for PLC diagnostics: offers dual current and voltage outputs useful for simulating sensor signals and looping tests
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
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2
Best Value Adjustable signal generator 4-20mA 0-12V DC for PLC testing
Best for precise loop testing: compact adjustable 4–20 mA and 0–12 V outputs ideal for focused PLC signal checks
Adjustable signal generator for 4-20mA current and 0-12V DC voltage output. suitable for PLC controller panel testing and LED calibration. customer notes indicate variable output depending on load
- 4-20mA/current and 0-12V DC outputs
- PWM pulse capability up to 150 kHz
- short circuit protection and high precision
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3
Healflux Custom Frequency Generator V2
Best for frequency-focused use: emphasizes tunable frequencies and relaxation-oriented waveforms for simple signal experiments
A frequency generator offering adjustable sine wave resonance, featuring 7.83Hz Schumann resonance for relaxation and sleep support. Easily tunable from low to high frequencies to fit personal needs
- 7.83Hz Schumann resonance
- wide 0.01Hz–20kHz adjustable range
- ultra-low to high frequency capability
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4
Riiai 4-20mA / 0-24V Current Signal Generator
Best for broader voltage simulation: supports wider voltage range and 4–20 mA capability for diverse bench and industrial simulations
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