[sdiy] Resistor switching and breadboards

[flightofharmony at comcast.net]

Two separate questions:

1) When using, say, a 4066 to switch a resistor into and out of a circuit using square wave PWM for "variable" resistance, assuming switching frequency is sufficiently high, are there any transients or glitches that may appear?

2) Breadboards. Grrr. I am constructing a synth and playing with a 555-based ADEG. I am also using one opamp out of an LM3900 to buffer the output. When I set the circuit to retrigger, it won't - unless I touch the lead of the feedback resistor connected to the inverting input. Then it works fine, either using my finger or needlenose pliers. Whaddahell!? I know breadboards are notorious for loose connections, stray capacitances and other such joys - any ideas about this one?

~flight