Found this Muson toy Synthesizer in the storage shed. Fired it up and it is in proper working order. Unfortunately it’s missing one of the sequencer plugs and currently only plays 9 of the 10 notes. This prompted me to open it up and try to determine the resistor value of the missing plug.

The 1978 Muson Synth toy. Perfect working condition, but missing one of the sequencer step plugs.

I poked around and found several interesting bends so I’ve decided to build a new custom case for this. I’m currently in process of removing all the control components that are mounted directly to the board and will move them to a new control panel.

Rewiring the controls and probing for bends.

More images here.
More to come…

After finding a supplier to the synthesizer in a single IC … the SN76477N (thanks to  Michael for the heads up on the supplier)  I’ve been doing further research into the possibilities of this IC and I’m pretty fired up to get working with it.

In case you’re not familiar with it, it was the chip that was used in this wonderful toy from the late 70’s.

The chip is capable of producing a ton of wacky synth sounds.  It was used in many early analog video games including Space Invaders.

“[T]he SN76477 generates complex audio signal waveforms by combining the outputs of a low frequency oscillator, variable frequency (voltage controlled) oscillator, and noise source, modulating the resulting composite signal with a selected envelope and, finally, adjusting the signal’s attack and decay periods. At each stage, the process can be controlled at the programming inputs of the signal modification and generation circuits, using control voltages, logic levels, or different resitor and capacitor values.”

– Lou Garner, Solid State, Popular Electronics magazine, October 1978.

There is a lot of potential here so this could be a fun one.  If you interested in learning more here’s a good resource.

Love this vintage packaging

I ordered some hard to find potentiometers from surplus sales of Nebraska and they came in this slick packaging.  this store has become my new favorite.  Not only do they have really rare, vintage and odd products in stock, their shipping was amazingly fast.