MATRIXSYNTH

Korg EXB-MOSS Modeling Synth Expansion Board for Triton

Toy KEYTAR Vintage Rhythm Guitar

via this auction

"It has the sound of a piano only, 23 inches long., black with strap. It has 8 buttons for rhythms on the neck., but I don't know how to turn them on! maybe that section is not working

You can choose a rhythm and speed, there is a demo mode, an a jack to plug in a microphone. runs on 3 AA batteries (not included) and includes the battery cover and a permanently attached black strap."

Roland Juno-106 HS-60 Audio Board

via this auction

the seller has some other parts here.

Art of Noise meets Roland D50

Listen to the track on
khoral's Cafe 80.

SCHIPPMAN Ebbe und Flut

flickr by unoq41

via the forum where it and a Cwejman S1 mkII is listed for sale.

Click on the bottom image and note how the letters on top are in reverse. You can view the labels when tilting the back of the unit up. Pretty nifty.

Acidlab Miami: All Boxed Up And Nowhere To Go....

via MaD:
http://acidlab.de
"The cases of the Acidlab Miami arrived and the prototype has now achieved his final look. The serial devices will become grey and white buttons instead of the red/yellow ones."

Be sure to click on the Acidlab label below for more including video. Click the image for the full size shot.

Oberheim Ob-1

via this auction

DIYing a Roland JX-8P DCO

This came in on the SDIY list via Tom Wiltshire. I thought it would be an interesting post on how these things get started and Tom gave me the ok to put it.

"Hi All,

I've been experimenting with a DCO design based on the Roland JX8P circuit

Broadly speaking, it works, in that I can get a ramp wave out of it if I adjust the 47K pot on the left. This pot and op-amp buffer will be replaced by a DAC when I get it working better. I've got reset pulses generated by a PIC being fed into the base of the transistor at 440Hz for the purposes of the test. That part is fine.

The problem is that the output goes from 0V down to -0.5V and then seems to saturate. What's going on? How can the op-amp output be saturated at only -0.5V when it's running on +/-15V rails? Everything I've read suggests that the output from an integrator ought to carry on as far as the op-amp output can take it, so I was expecting a ramp from 0V down to -15V or thereabouts. I'm sure there's something I'm missing here...

Thanks for any clues,
Tom"

Some clues did come in from members of the list including:
"Looks to me like base-collector parasitic diode starts conducting."
and
"The ramp is negative going, so Vcb is negative. That causes the base collector junction of your reset transistor to forward bias and limit the output voltage. You'll need to rethink the way you've got that reset transistor hooked up, or reverse the direction of the ramp so it's positive going (hint - invert the input to the integrator)."

followed by:
"Thanks both, that's sorted it. I simply swapped the polarity going into the integrator and as if by magic everything became hunkydory.

What I was missing was that Roland were evidently using a negative voltage. That isn't immediately clear from the schematic.

Instant solutions on this list...great suff!"

Why post this? Again, it's and interesting insight for those not involved in the SDIY community to see how some of this happens. Who knows, we might have a very nice Roland JX-8P VCO module or the like available one day. Pretty cool...
The Juno-106 replacement chips immediately come to mind.

Bebot Robot Synth for iPhone and iPod Touch

YouTube via normalware
"Bebot - Robot Synth
Available now in the App Store for $1.99
www.normalware.com "
You can find it on iTunes here:

Synsonics Drums from Mattel Electronics - Features & Demo

YouTube via saulocisneros
"This is a short review of the features of the 1981 Synsonics Drums drummachine/drumsynth from Mattel Electronics. 100% analog"