After successfully building the 555 timer circuit the next obvious step is to use this oscillator as a Control Voltage Source. The only problem is that the output from Pin 3 is a square wave either on or off. While great as a Pulse Out that can be used to power another circuit, it gets fairly boring as a CV source. What we need do is add a few extra components to give it that Warble. First the signal passes through a 10K resistor to limit the current, then charges the capacitor in turn discharging to the Ground during the Low phase of the 555. The output voltage is now in the form of a ramp and can be used as a CV.
To Connect the 555 LFO to the APC you can use the same circuit consisting of 10K Resistor and 10uF cap connected to the Ground. It is possible to play around with values, increasing the Capacitor value and also adding the potentiometer to make the Ground draining slower. The output of the LFO can now be connected to Pin 3 or Pin 11 on the APC circuit board. It is also possible to use separate LFO circuits going into both 3 and 11 as well as Syncing those together.
The above circuit is just an example to get some experimenting off the ground, feel free to modify the basic idea.
Here is a short example of the circuit in action: