I have copied the CD4060 part of the CMOS synthesizer in the link below to the letter, but it does not work. I am using a 12VDC SLA for supply. It tries to start when I tease the caps, but then dies.
I've spent hours tinkering to no avail. Can anyone see what is might be going amiss? Or can anyone please provide a similar circuit that works?
Steve Upton
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)
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
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
20pf for both the 100pF and for the 39pF caps. Also put a 20pF trimmer across the xtal to fine tune against a known good frequency.Good Luck, Chris Maness KQ6UP
Nah, noise is QR*N*. QRM is interference, usually other random lusers gassing about their equipment.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
Me, too. Amplifiers oscillate, oscillators don't ;-)
--
"Electricity is of two kinds, positive and negative. The difference
is, I presume, that one comes a little more expensive, but is more
durable; the other is a cheaper thing, but the moths get into it."
(Stephen Leacock)
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
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
The only thing bipartisan in this country is hypocrisy
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?
-- It doesn't. I think he was talking two binary inputs to switch between four output frequencies, so that's only 5 pins. JF
-- Or, pin-strappable means four hot pins and you strap to the one(s) that'll give you what (8,or 4,or 2,or 1MHz) you want, for a total of 6 pins. JF
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
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
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 :-)
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
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).
[1] Pin 9 is supposed to be open with xtal circuit.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
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
The only thing bipartisan in this country is hypocrisy
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.