Simulating the Affective Appeal of Retro Tektronix Wave Generator
In the golden age of Tektronix in the '80s, the company was a pioneer in test equipment, though much of it was still analog-driven. One marvel from this era is the SG505, an ultralow distortion oscillator module boasting less than 0.0008% total harmonic distortion across a 20 Hz to 20 kHz frequency range. enterprising electronics enthusiast [Paul] is currently attempting to recreate this iconic module using modern components, a daunting task given the scarcity of some original components and Tek's penchant for custom parts.
One of the hurdles [Paul] faces is sourcing the original J-FET Tek used in the oscillator's AGC circuit, a component that's become rather elusive. Another elusive component is a dual-gang precision wirewound 10k single-turn pot, used to adjust the frequency, making finding the perfect match something akin to a treasure hunt.
Despite being in the planning stages, [Paul]'s project promises to be an exciting adventure, and we can't wait to see the FFT results it yields. We imagine his custom curve tracer, a crucial tool in electronics, will make an appearance at some point during the build.
For those considering a similar project, here's a rough guide to help you embark on this retro engineering endeavor:
Understanding the Original Design1. Study the SG505's circuit topology and how it achieves ultralow distortion.2. Identify critical components like the dual-gang pot and any custom components.
Sourcing Rare Components1. For dual-gang precision wirewound 10k single-turn pots, explore specialty suppliers or online retailers dealing in vintage electronics parts.2. For curve tracers, source a vintage one or find a modern equivalent offering similar functionality.
Modern Substitutions1. Consider using modern digitally controlled potentiometers like the AD5254 for precise control.2. Replace active components like op-amps or VCOs with modern ICs offering low noise and high stability.3. Use high-quality passive components with low temperature coefficients.
Design and Implementation1. Simulate the circuit using tools like LTspice or SPICE to identify issues with modern component substitutions.2. Design a PCB that accommodates the selected components, minimizing noise and ensuring proper signal integrity.3. Assemble the circuit meticulously and test it thoroughly.
Tools and Resources- Modern semiconductor analyzers or simple curve tracer circuits using modern components can be used if a vintage curve tracer is unavailable.- Simulation software like LTspice or SPICE is essential for testing the circuit before building.- Seek suppliers like Digi-Key, Mouser, or online forums for vintage electronics enthusiasts for required components.
Though it may not be an easy feat, recreating the Tektronix SG505 oscillator module is an exciting challenge for any electronics enthusiast. With careful planning and strategic substitutions, you, too, can breathe new life into this iconic piece of test equipment.
A DIY enthusiast like [Paul] might find it challenging to source specific components, such as the J-FET Tek used in the oscillator's AGC circuit and the dual-gang precision wirewound 10k single-turn pot, which have become quite elusive due to the original piece's limited production and Tek's preference for custom parts. Utilizing modern substitutes, like digitally controlled potentiometers and high-quality passive components, could help overcome the scarcity of original components while recreating this iconic DIY project with contemporary technology.
