In case it is not clear, post #20, U4 Q2 is the 10 second output pulse.

Separate from that, there is no standard for how to name the outputs of these counters. I have two 4060 datasheets; the Nexperia goes from Q3 to Q13, and the National Semi goes from Q4 to Q14. In both cases, the Q3/Q4 pin is the output of the fourth counter stage. If you check the internal block diagrams, they are the same.

ak

 

Isn't CR5 shown in backwards?

The point of CR5 is when the diode gate is low it will be around .7 volts CR5 is my lame attempt to get rid of this voltage.

 

The point of CR5 is when the diode gate is low it will be around .7 volts CR5 is my lame attempt to get rid of this voltage.

I know what it's for but on your schematic it's in backwards.
How will Q1 turn ON with CR5 as seen in the schematic?

 

Oops.

 

Oops.

Are you going to edit the schematic so it's correct before someone else tries to use it.

 

Probably not.

 

Why would you post a schematic you know is incorrect ?

 

Oh OK, will fix.

 

How is the 4060 more accurate than a 555?
Both use RC as timing. The accuracy depends on the variation in the R and the C. These are independent of the values.

 

How is the 4060 more accurate than a 555?
Both use RC as timing

The argument is that 4060 can use much smaller capacitor values to obtain the longer delay times. Assuming the smaller caps have less leakage.

 

How is the 4060 more accurate than a 555?
Both use RC as timing. The accuracy depends on the variation in the R and the C. These are independent of the values.

For small delay times that is true.
For long delay times, the large RC values required by the 555 lead to leakage issues (especially from electrolytic capacitors which have high leakage and poor capacitance tolerance) that reduce the 555 timing accuracy.

 

In terms of just the silicon, a 555 is much more accurate than a 4060. That is, it contributes less error to the overall circuit's predictability (calculated frequency versus actual frequency). The issue with the 4060 is that the frequency is affected by variations in the CMOS gate input transition level. This is not a tightly controlled parameter.

OTOH the 555 has two analog comparators with decent performance for its time, plus a reference voltage divider stack that naturally accurate to 1% without laser trimming, and has near-perfect temperature tracking. IIRC the datasheet says the device contributes 2% or less to the output frequency accuracy. That was a big deal because when the chip came out, a 1% resistor cost a dollar in low quantities. Also, the circuit's performance is ratiometric with respect to Vcc, almost completely eliminating errors due to variations in the circuit's operating voltage.

The big advantage with the 4060 is that for the same output period, the capacitor size is either 8,192 or 16,384 times smaller than with a 555. Depending on the circuit, that can be enough to change from a +/-20% electrolytic to a 1% film capacitor that also is smaller and costs less.

ak

 

Digital is always going to beat analog. With crystal controlled oscillators timing is much more predictable but if you need simple the 555 is the way to go just understand that there is a sacrifice in accuracy using it.

 

Digital is always going to beat analog.

Good enough is the enemy of best.

ak

ps. The quote isn't an actual quote. It is a re-working of a quote by Voltaire: The perfect is the enemy of the good.