CD4060 Xtl Osc. Circuit

I never buy crystals for things like this. They have a high probability of not working, and you wind up fiddling with capacitors and such. It's easier to but a packaged, working crystal oscillator, already tuned to a couple PPM, guaranteed to oscillate, for $1.50 or thereabouts.

John

Not knowing which frequency you are using, the 100k is way too low. I never go below 1M. Also, the burden caps are highish, 100pF is a bit much.

Yup:

How on earth could you guys call your club bulletin "QRM"? ... :-)

(for non-hams: QRM means noise, of the undesired kind, meaning not from a rock band and stuff)

Steve, this does not strike me as the best circuit for the crystal. I just built a crystal oscillator with a CD4060, and it worked great. What frequency are you using, and what is the capacitance of the crystal? I will make it work on my spice model to test it as well.

Regards, Chirs Maness KQ6UP

I agree, if you want to try to get it going use 2Meg for the 100k resistor and the 2k2 is fine for the power limiting resistor. Try

Good Luck, Chris Maness KQ6UP

Nah, noise is QR*N*. QRM is interference, usually other random lusers gassing about their equipment.

Cheers

Phil Hobbs

Me, too. Amplifiers oscillate, oscillators don't ;-)

We've just started using silicon oscillators, in SOT-23 sized packages, for things where 1% is good enough. We're using one part that's pin strappable for 8-4-2-1 MHz.

John

How are you constructing this? Breadboard? If so - the 10pf beween every strip can really screw htings up.

What crystal are you using?

The pi network components are frequency/crystal dependent... "...tries to start when I tease the caps" suggests that's your problem. ...Jim Thompson

A seven pin SOT-23?

I think its this Linear part

There are others tho.

Cheers

Neat (but sloppy - 1/5% to 2% error). That's a trinary input (1/10/100) in a SOT-23-5. John was suggesting 1-2-4-8 binary inputs. I've never seen a SOT-23-7. Up to six pins on a "SOT-23" I can understand, but where does the seventh pin go?

Ah, that would make sense. When I see 1-2-4-8 I naturally assume a 4-bit binary sequence. With only a binary divider it's even less interesting.

Probably an SOT-23-8.

There are some 32-bit microcontrollers in 33 pin packages. The thermal pad is the ONLY ground pin IIRC.

Best regards, Spehro Pefhany

I think the definition is that QRN is atmospheric noise. Distant lighting and so on. QRM is man-made noise which is in the majority these days. Switch mode supplies, CF lamps and so on. And yeah, also splatters from the guy 5kHz down the road gassing about his big honking amplifier :-)

Funny you mention that, I ended placing a small cap (22pF) from pin 9[1] to ground to get reliable oscillation -- but that was at 8MHZ with a HC4060. A later circuit I used capacitor instead of the series resistor to the crystal (as recommended by the HCMOS oscillator appnote).

I know this doesn't directly apply to OP's issue, but it shows 'finger' teasing can give an idea whether the circuit is trying to oscillate.

Grant.

My rule of thumb, which seems to work with every inverter-style crystal oscillator I've ever tried: Use capacitors as recommended by the crystal specification... if it says 15pF, that means 30pF on EACH end to ground. Then choose the resistor based on 45º phase shift with the first capacitor (at the crystal frequency). ...Jim Thompson