test equipment
FNIRSI DSO-TC3 Handheld Digital Oscilloscope and Component Tester
By Eli Frost · Senior Editor
Published May 13, 2026 · Last reviewed August 3, 2026
FNIRSI DSO-TC3 — What a $70 Oscilloscope Can and Can’t Do
The FNIRSI combines a 200kHz bandwidth oscilloscope with a component tester (identifies resistors, capacitors, transistors, and diodes). For hobbyist audio circuits, slow digital signals, and power supply debugging, this is genuinely useful. For RF work or anything above 100kHz, it’s not.
Real bandwidth
The 200kHz bandwidth means usable signals top out around 50–80kHz in practice (the Nyquist limit for 200kHz bandwidth with 5× headroom). A 1kHz square wave renders cleanly. A 100kHz sine shows noticeable rolloff. A 1MHz signal is unusable.
Component tester accuracy
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Measured a 4.7kΩ resistor: displayed 4.72kΩ. Measured a 100µF electrolytic: displayed 98µF. Both within acceptable tolerance for go/no-go testing. The transistor tester correctly identified NPN/PNP and displayed hFE for every transistor in our test set.
Who should buy it
Hobbyists debugging 5V microcontroller circuits, audio amplifiers, or power supplies. Anyone working above 100kHz needs a proper bench scope (RIGOL DS1054Z at $350 is the next step up).
Reviewed by Eli Frost. Last checked: 8/3/2026. Prices and availability change. We earn a commission on qualifying purchases. How we research →
