I don't really have a 15M resistor - i don't even think the shop even sells them either...

http://www.reuk.co.uk/Making-Very-Accurate-Timers.htm

That 15M resistor just left of the timing crystal, what is it for? Is it possible to just go up to 10M? (since i have 10x 1M)

 

I believe they are dividing the crystal down to a 2hz timebase

You can use your 10M and a 5M in series.

 

But then that would dwarf the 330k resistor? Im not even sure what that is used for lol

Silly question of me but I haven't used crystals before, but why do i even need resistors in that section? Surely the crystal isnt going to produce a whopping current

Looking here:
http://www.electronics-tutorials.ws/oscillator/crystal.html

The crystal is just connected directly to the chip (even though it is a microprocessor, a 4060 still has the same inputs - ish)

 

I believe it is to reduce any voltage differential across the crystal. Such voltage can lead to aging and reduced lifetime.

 

Its how the 4060B takes the pulses. The difference between pins 10 and 11 set the 4060B count speed.

 

Soo... It is a definite 15M then? Or a mis-type as retched said earlier?

 

http://www.fairchildsemi.com/ds/CD/CD4060BC.pdf

Page 3 of the datasheet shows how to set it up.

It shows a 15M and a 330

 

Darn it - anyway thanks for the help

 

What are you trying to do, I may be able to help.

You can add up a bunch of resistors to = 15M..It doesn't have to be 1

 

Oh I was just making a 1Hz clock generator - looking through my parts bin I realised I had not a resistor above 1M

However on Maplins there is a 10M, 3M9 and a 1M resistor, I do have a 100K though - I could just couple them all together and get it that way as you said

I only made this topic to see if there was a way round me buying even more stuff

 

I think the only conceivable purpose for that is static discharge.

eric

 

The 15M value is not terribly critical.
Try it with 5M and see if it works.

The point of it is to make certain that the oscillator starts. Without that resistor, the oscillator could get "stuck" on start-up.

 

Hi Peck68,
Just out of interest what does that circuit do.... and its use?

cheers
redlight000

 

It divides the 32768Hz xtal frequency down to a 1-second pulse. Very useful for clock projects.

 

The 15M resistor is there to bias the CMOS gate that is used as a crystal oscillator. The value is not critical. High as possible but 10M will work OK.

 

It divides the 32768Hz xtal frequency down to a 1-second pulse. Very useful for clock projects.

Actually it is 2 Hz minimum. You need another external flip flop, but other than that I agree totally with Wookie, including the try alternatives and see if it works.

 

Shouldnt need to? The 2Hz is divided by 2 to make 1Hz? Anyway

I cant understand why my led isn't lighting i tried it with just the 4060 to get it to flash every 0.25 secs - yet its not even lighting up at all

Is it a dud CMOS or crystal? I am using a 10M resistor instead of 15 by the way

---

Edit: Ahaaa, sorry i am so stupid

Had the resistor that connects the led a row below it (i keep doing this with breadboards) so it wasn't getting any power

Flip flop works good by the way, no need for another one (unless i want 0.5hz)

 

Show us how your doing it (a schematic). CMOS doesn't drive LEDs very well, you'll need something like this...

It is also entirely possible that your oscillator isn't oscillating.

 

No it does work now - just didn't have it connected up properly

(except its a 10M resistor instead of 15, and those 1k resistors are 10k)

 

How did you wire it up? I betting not a protoboard, but I would be interested if I were wrong.