CD 40106 IC - making simple oscillators & LFOs

Some notes on making simple LFOs and oscillators using a CD 40106 IC

I'm using a common CMOS  CD40106 chip.

The 40106 is a hex inverting Schmitt trigger.

It contains 6 inverters.

What makes this chip so special is that the inverters are relatively immune to circuit noise.

As with all CMOS chips, it's sensitive to static electricity.

Square wave oscillator

There is no CV, but this can be added later.

I added a LED to indicate when its active.

Parts

CD40106

LED (Blue)

3.3K LED resistor

10k

100k pot

0.1uF cap. (104) --- the value of this cap will determine the rate/speed of the oscillator

Square wave LFO

The circuit is very similar to the square wave oscillator 

It's important to ground any inputs you are not using. ... esp if you are not building all six oscillators.

Parts

CD40106

LED (Blue)

43K LED resistor

10k (experiment with this)

100k pot

1uf to 10uF cap. (Electro) - (cathode to gnd)

This cap will determine the rate/speed of the oscillator, so play around with its value.

The frequency is a function of the capacitor & resistor.

The higher the capacitor or resistor, the slower the frequency.

The cd 40106 can output two waves: square & triangle.

The square wave is pretty strong, but the triangle is quite weak, In order to use the triangle wave you will need to buffer it (with an op-amp).

re the potentiometer:

I only use 2 terminals.

Just use it as a variable resistor (not a voltage divider).

I'e also added a LDR to vary the resistance.

A ribbon strip would also work. 

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As the CD 40106 chip has 6 inverting Schmitt triggers why not build 6 LFOs

..

.

All used a blue LED with a 2.7k resistor. I changed the cap values for each LFO to get different speeds

Out 1:  10K resistor + 100Kpot + 22uF cap

Out 2: 10K resistor + 100Kpot + 47uF cap

Out 3: 10K resistor + 100Kpot + 10uF cap

Out 4: 10K resistor + 100Kpot + 3.3 uF cap

Out 5: 10K resistor + 100Kpot + 1uF cap

Out 6: 10K resistor + 100Kpot + 100uF cap