ComputerSphere – restoring the original knobs and dials

The two large knobs were the reason the project stalled for so long, I initially planned to use the knobs to control the LCD TV, interfacing the knobs to the digital up/down buttons.

The idea was, since the knobs are rotary, I needed some way to convert the clockwise and anticlockwise directional rotation to two corresponding digital pulses. Searching the internet, I found an incremental quadrature rotary encoder could be used to achieve this.

I initially purchased two inexpensive mechanical quadrature rotary encoders for roughly $3 each and a couple of “and” gates, with information found on the internet I put together a simple quadrature decoder  with two LEDs that would light up depending on rotation direction, unfortunately, this didn’t work.

Basic PCB mount rotary quadrature encoder by Alps
Alps rotary encoder mounted with And gates

This lead me to thinking that the mechanical bounce was the problem, so I purchased two Grayhill 62P22-H0 optical rotary encoders for $10 each from RS Components, this also didn’t work.

62P22 optical rotary encoder with quadrature output

I was then thinking that my “and’ gate setup was causing the problems  so I purchased two quadrature clock converter ICs from LSI chip model LS7083, these cost about $30 including shipping to Australia. These chips allow for a rotary encoder with quadrature output to connect directly to the IC, the chip then converts the clockwise and anti-clockwise rotation to up/down pulses. Unfortunately, this still didn’t work.

Breadboard with two And gate chips and LEDs for direction indication
Slightly heavier mechanical rotary encoder

This was enough for me to drop the project, hence the long leave of absence.

What made me restart the project was I found some rotary switches from company Taiwan Alpha part model 105-SR10030F-PS. What makes these rotary switches so special is they directly output on/off pulses when rotated, they don’t output a quadrature signal, so there is no need to have any hardware that decodes the quadrature signal. This cost me around $50 including shipping. When they arrived I restarted this project.

Rotary switches from Mouser SR10030F

As it turned out,  since I couldn’t use the analogue tuner of the LCD any more (analogue was phased out by digital free to air), I had no more need to convert the volume and channel controls.

So below is a straight forward restoring of the original knobs.

The original two knobs from the Videosphere
Mounting the two knobs on the original Videosphere bracket
The view from inside, Via Epia M motherboard visible
View of the two knobs from the outside

I’ve also starting thinking about what to show on back of the Videosphere, things like power buttons, power connectors and cables. I have an idea to have only USB plugs available. In the square base there will be a slot load DVD-RW drive connected via USB.

Back of the original Videosphere