The 'Safety PIN' - Adds modulation Straight to the Synthi matrix

This was an idea running in my head for a while ... why not to add some CV into the Synthi matrix using a pin with an Optocoupler inside ? This way the Synthi can be integrated with a modular synth for example and get more modulations options to each and every section you chose straight through the matrix. the Optocoupler makes it very safe and the Synthi circuits will never get exposed to high voltages Or spikes. The special pin can be placed in one of the joysticks rows, this way the modulation anount can be controlled. i made the pin today and placed everything inside a small tube which i took from a panel bulb and wrapped everything with a shrink. i also added a 2.7K resistor to the input in order to protect the LED inside the coupler. The CV  into the pin shouldn't exceed 5V.
 The results are just fantastic!!!  now i need to make some more pins ...