Projects

Prototype Audio Level Meters

These were my own design in audio level meters. This prototype was built to test in my next prototype audio controller. This design uses the LM3916N Dot/Bar display driver chip, and measures line-level audio signals. I got the 10-segment LED bargraph displays from Radio Shack. These work GREAT on line-level audio signals and are very fluid and responsive, allowing both dot and bar modes.

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Prototype Audio Controller Power Supply

For my next project I broke things up into stages. The first step was to build the power supply for the audio controller section of my next amplifier. This is a 3-way power supply for that audio controller. The various circuits within the controller required 5VDC, 12VDC and -12VDC. This supply was designed to handle all of those needs. It used 2 transformers and three voltage regulators with heat sinks. 

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Prototype Multimedia Amplifier

As computer audio devices got better I felt a need for a better amplifier for my PC with more inputs so I could still have my SNES and Genesis connected. I also wanted to be able to see the level of the audio signal. This prototype had electronic input selection via four push-button switches on the front wired through logic into a special IC, the National Semiconductor LM1037N stereo audio switcher. The output of this amplifier used the LM2879 Dual 8-Watt amplifier IC, also by National Semiconductor.

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Production SNES / PC Amplifier

This was an 8-Watt/channel version of the prototype. It used two LM383 Amplifiers. This final version also had an input selector for switching between your SNES and/or Sega Genesis, plus a better case with venting. This unit is still in use today by some old friends, although a couple say the volume control is a little crackly when adjusting it. I sold many of these to hardcore console and PC gamers.

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Prototype SNES / PC Amplifier

This was a 2-Watt/channel audio amplifier designed for Super Nintendo or computer sound cards. This prototype used an integrated amp IC, volume control, power switch, power light, etc. The power supply was a surplus wall transformer, rated 15VDC @ 1000mA. This unit is still in use today by an old friend in NY. This project was a good example of what could be built using some spare parts found in my myriad of parts cabinets and drawers. 

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Z80 Control Board

Through the late 80s and early 90s the Zilog Z80 was my favorite CPU to work with. I loved the architecture, instruction set, capabilities and vast array of support chips available. I started designing commercial Z80 boards around 1992 and the early designs were built on perf-board and wire-wrapped. This article discusses a couple of early boards I made, the design, the development tools I used and even some example code.

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