Design of a low cost multifunctional electronics laboratory test equipment

Numerous commercially available multifunctional electronic laboratory test instruments, integrating functions such as oscilloscopes, signal generators, and logic analyzers, are typically priced above 250 USD. However, no widely adopted multifunctional test instrument is available in the 100 USD price range. Designing a stable and widely accepted instrument at this price point is expected to enhance the quality, performance, and effectiveness of practical applications in electronics education. To achieve this, all relevant academic studies and commercially available multifunctional devices were analyzed, leading to a comprehensive re-evaluation of all design approaches. Components such as the data acquisition unit, signal generator, power supply, logic analyzer, and display interface were reassessed to develop a stable device adhering to the principle of minimum cost and maximum functionality. During development, the Analog Front End (AFE) unit, a major cost driver within the data acquisition unit, was optimized to meet these goals effectively. The designed data acquisition unit employs a carefully developed architecture featuring a four-stage attenuator and a three-stage operational amplifier (Op-Amp) gain unit, addressing key limitations in existing designs. The resulting AFE unit achieves a ±40 V input voltage range, 39 µV amplitude resolution, 0.1 dB linearity error up to 5 MHz, and a -3 dB bandwidth of 20 MHz. Additionally, it offers a rise time of 16 ns, a voltage gain of 540 (V/V), and a peak-to-peak noise amplitude of 54 mV. The achieved bandwidth and high-speed gain adjustment configuration demonstrate that the designed AFE can support applications such as ultrasonic Time Gain Compensation (TGC).