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16 May 2014

Original Apple 1 setup – demo of a working piece of history

This is one of 6 known working original Apple 1 personal computers from 1976. There were about 200 Apple 1 ever built and 43 units are identified to exist to date (08.2012). This Apple 1 had been originally restored and framed in 1993 by an Apple enthusiast. I restored this machine in 2012 to fully working condition (there was a faulty PROM) and attached an ASCII keyboard, monitor, power supply and an ACI (Cassette Interface). In the demo the machine executes some test programs and loads from cassette BASIC and a graphics demo.

The original Apple 1 came only as ready built motherboard: there was no keyboard, no case, no monitor and no power supply included. The buyer/user had to find and attach the peripherals himself.

The machine is pretty solid now – I booted this A1 more than 50 times in the last 2 weeks and it worked flawlessly.


Original Apple 1 setup – demo of a working piece of history - [Link]

13 May 2014

This tutorial presents the basics of the varactor diode, or varicap diode, and describes how it functions as a voltage controlled capacitor. A test fixture is shown and used to measure the capacitance vs. reverse voltage. Finally, a voltage-controlled oscillator circuit is built and measured, showing how the voltage on the varactor diode is used to tune the frequency of the VCO.

Basics of Varactor Diodes | Voltage Controlled Oscillator VCO Example - [Link]

10 May 2014

A quick look at the new Siglent SDS2072 super phosphor digital oscilloscope.
A quick look at the bench power supply project and a component list.

T4D #100 – SIGLENT SDS2000 and Power Supply Project - [Link]

10 May 2014

A short video sharing the excitement of unboxing a new Tektronix MDO3000 Mixed Domain Oscilloscope!

Unboxing the Tektronix MDO3000 Oscilloscope - [Link]

10 May 2014

Detailed look at methods for driving LED matrix displays, including simple LED displays and full-colour video screen modules.

Driving LED matrix displays with an FPGA - [Link]

10 May 2014

Dave attended the Cebit 2014 event in Sydney at Homebush Olympic Park. Here are some highlights.

EEVblog #614 – Cebit 2014 Highlights - [Link]

5 May 2014

What’s inside a $13K Agilent Source Measure Unit capable of 15fA and 100nV resolution?

EEVblog #607 – Agilent B2912A Source Measure Unit SMU Teardown - [Link]

3 May 2014

Doug Ford, former head designer from Rode Microphones continues with Part 2 of the microphone technology series by explaining the construction of noise cancelling Figure 8, cardioid, and hyper cardioid microphones. Also, how the polar patterns and responses relate to the physical construction, and how the frequency response is affected.
Proximity boost effect,
Microphone calibration is also discussed using a home made artificial voice speaker box.
And practical considerations about foldback wedges used in stage performances and how to avoid feedback using proper microphone technique.

EEVblog #605 – Fig.8 & Cardioid Microphone Patterns - [Link]

25 Apr 2014

This video describes the basic concept behind eye patterns on an oscilloscope and how they can be used to evaluate the quality and signal integrity of a serial bit stream or data stream. It discusses how signal impairments such as jitter, ringing, overshoot, undershoot, noise, etc. can all be evaluated on a serial bit stream using an eye pattern.

What is an Eye Pattern on an Oscilloscope - [Link]

22 Apr 2014

H-Bridge Motor Speed Controller Tutorial - [Link]





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