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bilateral switch problem

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heuron

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hi. i am making a tone generator with a 555 astable circuit that i wanted to be able to go up an octatve. the way i do this is through connecting a resistor of equal resistance as the timing resistor in parr. with the timing resistor so as to half it's resistance. i decided to use a 4066 quad bilateral switch for this because it could switch 4 at a time, so whenever i trigger the control pin, it connects the two I/O pins which connect a trimpot in parr. with the timing resistor. it works fine when the 4066 is on, but when it is off the tone qualty is horrible and the frequency floats about a little. also, i can adjust the overall timing resistance using the 2nd timing trimpot (the one connected to the 4066) when it isnt even being triggered! what can i do to fix this? thanks.
 
I can't claim credit for this idea - because it's just "how it's done".

Run the 555 at your higher octave, and use a bistable to divide down to the octave below - you can then switch octaves simply by switching between the input and output of the bistable. By using more than one bistable you can get all the octaves you need - this is how electronic organs commonly worked, 12 master top octave oscillators, with dividers down for the lower octaves.
 
heuron said:
......whenever i trigger the control pin, it connects the two I/O pins which connect a trimpot in parr. with the timing resistor. it works fine when the 4066 is on, but when it is off the tone qualty is horrible and the frequency floats about a little..... .
You can't 'trigger' a 4066 on. To switch it on you need to keep the gate high, and to switch it off the gate must be kept low. If you are only switching the gate high to turn it on you need a pulldown resistor to keep it switched off.
 
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