Wednesday, December 26, 2012

Hammond Tone Generator Project - Part 1

Early this year, I acquired a tonewheel generator (TWG) from a Hammond series H organ. The H series was rushed into production to compete with offerings from other organ companies, and suffered reliability problems as a result. Here are some photos :
The Tonewheel Chronicles
This TWG had already been removed from the organ and was headed for the dumpster when I picked it up. I have bolted it to a wooden frame to prevent flexing. The Hammond tonewheels organs were produced from 1935 until 1975. Tones were generated by spinning a toothed steel wheel next to an electromagnet. The wheels rotated at a fixed rate, locked to the speed of the synchronous motor. When operating properly, the TWG never went out of tune. This was an improvement over electronic oscillators, where at least 12 oscillators must be tuned to their appropriate pitches. Here is a more extensive description : So, what can you do with a TWG from a Hammond organ? First, I needed to test the TWG to make sure that it was operating properly.

Sunday, November 18, 2012

Synthesis on the Parallax Propeller

Have been experimenting with audio synthesis on the Parallax Propeller chip. The Propeller is a 8 core multiprocessor chip that can be purchased for $7. It is remarkably capable...the processors share the I/O bus on a time slice basis, so each processor knows when it has access to the I/O bus. Anyway... There is discussion on the forums about a SID Synth project. It runs an emulation of the Commodore 64 SID chip in 4 of the 8 cogs (processors). The processor accepts MIDI input and passes the note commands to the various cogs. Here is a link to the forum discussion : Even more interesting, the circuit is capable of digital audio output via a simple RCA connector, using the S/PDIF protocol. I am using it with a $20 S/PDIF to Analog audio converter. I have the digital audio working, unfortunately not yet with the SID emulation. WIll be working on this. While this is nothing like having real SID chips, it is pretty impressive for what it can do.

Thursday, September 20, 2012

Microsoft Family Security. Useful? Not Really.

I'm trying out Microsoft Family Security on our Windows 7 box. Following is the list of software that my son is "using". Completely accurate, but pretty useless. There are 3 real programs in here : Google Chrome, Nero and Snagit Most of this stuff runs in the background all the time. Apparently there is no way to exclude this background nonsense from the report. I don't want to disallow it, because then everything breaks :

Citrix online plug-in Connection Center 4 hours 8 minutes

Event Monitor User Notification Tool 4 hours 8 minutes

Google Chrome 4 hours 8 minutes

HP QuickPlay Resident Program 4 hours 8 minutes

HPWAMain Module 4 hours 8 minutes

hpwuSchd Application 4 hours 8 minutes

Internet Low-Mic Utility Tool 4 hours 8 minutes

Saturday, June 02, 2012

Politics : Don't like the facts? Legislate them away

Our legislature in action : Climate change may be illegal So, if you don't like the science, make it illegal. This is the legislative equivalent of putting your fingers in your ears and saying "La La La, I can't hear you.

Wednesday, February 22, 2012

Project : Clavinova - where to go from here?

My attempt at repairing the Clavinova CVP-87A did not help (the audio output still sounds terrible), but there was a silver lining. It turns out that the MIDI out still works. I am currently using a Yamaha external MIDI sound module as the sound source. I disconnected the audio output of the mainboard, and connected the audio output of the MIDI module to the external input of the Clavinova. Unfortunately, there is no volume control of the external input -- the volume controls on the Clavinova do not work.

So, it is a perfectly good learning piano. I take my piano lessons on it. I love the way it plays. However, I can only control program changes. The first 10 are on their own buttons, the other 50 are available through more keystrokes. None of the other controls work, including the floppy disk interface. Every key has a corresponding LED, which is used to indicate the position of keyboard splits, among other things.

So my options are :

  • Purchase a new mainboard for about $500, which leaves me with a Clavinova and its' 1993 era voicings. Next year it will be 20 years old.
  • Do nothing and continue to use it as a piano controller with a bunch of non-functional controls. This is practical, but somehow dissapointing.
  • Replace the electronics with something more modern. I have looked at commercially available MIDI controllers. Almost none of them provide for velocity sensing and very few provide for control of 88 keys.

I have thought of building a computer inside the Clavinova. There is plenty of space. I could probably salvage the amplifier boards, but not much else.

Friday, February 17, 2012

Logitech Orbit AF - Only in Ubuntu :-)

Grabbed an old Logitech Orbit AF cam to do some video conferencing. Logitech does not support this device under Windows 7, and Mac OS X does not recognize it. Finally tried Ubuntu 11.10 and the camera WORKS, though the audio does not. Amusing.

Friday, February 10, 2012

It's been awhile : new HP laptop series naming?

It's been a while since I posted. HP has just come out with a new line of laptops -- The HP Spectre. Looked up the definition of spectre on the Free Dictionary : spectre US, specter [ˈspɛktə] n 1. (Spirituality, New Age, Astrology & Self-help / Alternative Belief Systems) a ghost; phantom; apparition 2. a mental image of something unpleasant or menacing the spectre of redundancy Hmmm.