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"If you want to be an Electrical Engineer, build an oscilloscope - from Scratch."

This was my mission in the early '90's. I had a Bachelor's in Product Design from Stanford, but still felt that I needed to learn more electronics. I got some basic training through a one-quarter class at Heald, and then set out to put that knowledge to work.

What the Binder-Scope is designed to do is is "capture waveforms", like an oscilloscope or EKG. The circuit has the following sections -
* 32,768 Hz clock, to be divided down into 2^X frequencies.
* An array of Negative Leading Edge Triggered JK Flip Flops (LS 112), using inverters and AND gates to time consecutive channels for a signal capture.
* A Ladder of Voltage References and Resistance Dividers. The Display circuits have 24 LED's (no LED for zero volts).

The first iteration of the design I do not have a picture of. A matrix of 16 x 12 LED's in a shiny aluminum case.

The second iteration of the design is Binder-Scope. What I envisioned was a simple waveform capture device that could fit in a 3-ring binder.




This image shows some of the details of the circuit. On the left in the middle is the voltage divider circuit. The device under test is probed for voltage and compared against the voltages in the voltage divider circuit.

The design worked in .2 volt increments. For example, the comparator reads a voltage of .8 volts as reason to light up 4 LED's, on the +side. A voltage of -.6 volts would light up 3 LED's, on the -side.

The comparator output is transferred to the devices that drive the display. Shortly thereafter, once every clock-tick, the comparator section takes another voltage reading. The LED's hold their position for one "sweep".




I enclosed a father's day encryption on this revision of the design.




I asked an electrical engineer co-worker at one R&D facility to give me some feedback about the circuit. He looked at the block diagram & schematic & said it would work, that it was realistic, etc. He said that the circuit would be good to about 250 MHz.

It was difficult to work with the circuit. The circuitry was a little too small for soldering wires and the single-sided circuit board had some broken traces. Therefore I undertook to construct a larger circuit, using individual display channels connected by a bus, mounted in a wood chassis.




A close up of an individual display channel. This takes a comparator output over the bus, lights up the corresponding number of LED's to represent a voltage, positive or negative, and holds it for one sweep cycle.




I would like to repeat the exercise, but not as a solo project.