Hammond Organ sends messages which can be decoded by a Spectrogram

hammond-organ-encodes-messages-spectrogram

Here’s an interesting use for an old organ. Let it get in on your Ham radio action. [Forrest Cook]  is showing off his project which uses a Hammond Organ to encode messages which can be displayed by a Spectrogram. We’ve seen this type of message encoding before (just not involving a musical instrument). It’s rather popular with Hams in the form of the fldigi program.

An Arduino was connected to the organ via a UNL2003 darlington array chip. This chip is driving some reed relays which make the organ connections to create the sine wave tones. With that hardware in place it’s a matter of formatting data to generate the target audio. [Forrest] wrote his own Arduino sketch which takes characters from the serial port (pushed over USB by the laptop), maps then to a stored 5×7 character font set, then drives the pins to produce the tones. As you can see in the clip after the break the resulting audio can be turned into quite readable text.

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Making old organs more portable with MIDI

In the 60s 70s and early 80s, roadies would lug hundreds of pounds of musical equipment around to gigs. Although the 8×10 Ampeg bass cabinet wasn’t fun in the least, the absolute worst was the Hammond organ. These behemoths of tonewheel organs sounded great, but moving them was a pain. For better or worse, portable MIDI keyboards caught up with the sound quality of these old electromechanical monsters. Everything is still not right with keyboard players; a good set of organ foot pedals is still hard to come by. To solve this problem, [Jeremy] converted his old Hammond A-100 organ pedals to MIDI giving him all the feel and aesthetics of an ancient instrument without all the heft.

To transform the ancient A-100 bass pedals into a keyboard, [Jeremy] turned to the HighlyLiquid MIDI CPU. This small board provides a few dozen pins to wire up to switches and potentiometers. A new switch assembly was built for the bass pedals using a momentary push button switch under each key. These buttons are wired up to the MIDI CPU, and everything worked out wonderfully.

Although there’s no video of the newly portable Hammond organ in action (something off Zeppelin I, [Jeremy]…) there is a great Flickr photoset of the entire build. Awesome work, [Jeremy]