my frequency adjuster

I am able to fine tune the frequency by pushing a button, and using the 4040 binary counter.

In order for me to obtain good steps, I must place some capacitors in parallel, and some capacitors in series, because there is no store that sells capacitors in exact multiples.

I want capacitance to be from 1 to about 16 pF.

If I were to use single capacitors, then the bits in the counter (if I only use 4) will be as follows.

Bit 0: 1.2pF
Bit 1: 2.2pF
Bit 2: 4.7pF
Bit 3: 8.2pF

Here's the problem. When counting, I want to see:

1.2pF, 2.4pF, 3.6pF, 4.8pF, 6.0pF.... and so on.

According to the bits above, I would get:

1.2pF, 2.2pF, 3.4pF, 4.7pF, 5.9pF, 6.9pF, 8.1pF, 8.2pF.... and so on.

As you can see, the count is uneven.

Are there any better capacitor values that suit this application?

I want the even-most count without making my circuit consist of 99% capacitors.

Maybe you can use cap trimers or varicap diode with adjusted voltages selector.

thanks, but using varicaps will require me to buy specialized tools to measure capacitance, and I don't use varicap diodes. They are more expensive.

You do not need to measure capacitance but only frequency. Actually you have to set correct frequency for each step by potentiometer.

Where are you going to find 1 percent caps in this range? You would be better off to invest in a $50 cap meter and use trimmers which are easy to find in this range.