CD4060 Xtl Osc. Circuit
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From: Boris Mohar on 14 Mar 2010 10:19 On Sat, 13 Mar 2010 00:20:46 GMT, steveupton(a)gerber.com (Steve Upton) wrote: >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? > >http://www.redclifferadioclub.org.au/QRM/2006%2010%20-%20October%20QRM.pdf > >Steve Upton I don't see any local decoupling caps. -- Boris
From: Joerg on 14 Mar 2010 12:05 Jim Thompson wrote: > On Sun, 14 Mar 2010 10:42:55 +1100, Grant <omg(a)grrr.id.au> wrote: > >> On Sat, 13 Mar 2010 11:01:11 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >> >>> On Sat, 13 Mar 2010 00:20:46 GMT, steveupton(a)gerber.com (Steve Upton) >>> wrote: >>> >>>> 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? >>>> >>>> http://www.redclifferadioclub.org.au/QRM/2006%2010%20-%20October%20QRM.pdf >>>> >>>> Steve Upton >>> 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. >> 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 ... Now, now, guys, keep it civilized here, will ya :-) >> ... 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 45� phase shift with > the first capacitor (at the crystal frequency). > I am usually happy with around 1M. All it needs to do is to crank it over. Kaaaa-chum-pah ... POOF ... vrooooom. Unless I must start it really fast for some reason but that can require special kicker circuitry. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jim Thompson on 14 Mar 2010 12:29 On Sun, 14 Mar 2010 09:05:27 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Jim Thompson wrote: >> On Sun, 14 Mar 2010 10:42:55 +1100, Grant <omg(a)grrr.id.au> wrote: >> >>> On Sat, 13 Mar 2010 11:01:11 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >>> >>>> On Sat, 13 Mar 2010 00:20:46 GMT, steveupton(a)gerber.com (Steve Upton) >>>> wrote: >>>> >>>>> 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? >>>>> >>>>> http://www.redclifferadioclub.org.au/QRM/2006%2010%20-%20October%20QRM.pdf >>>>> >>>>> Steve Upton >>>> 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. >>> 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 ... > > >Now, now, guys, keep it civilized here, will ya :-) > > >>> ... 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 45� phase shift with >> the first capacitor (at the crystal frequency). >> > >I am usually happy with around 1M. All it needs to do is to crank it >over. Kaaaa-chum-pah ... POOF ... vrooooom. Unless I must start it >really fast for some reason but that can require special kicker circuitry. Huh? You and I are talking two different resistors. I'm talking the series drive resistor; you're talking the DC loop resistor. Which brings to mind... does the CD4060 have the DC loop resistor built-in? It would appear not. And I should pay closer attention to details :-( The OP has 100K there... needs to be 10-20Meg. ...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
From: Joerg on 14 Mar 2010 12:51 Jim Thompson wrote: > On Sun, 14 Mar 2010 09:05:27 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> Jim Thompson wrote: [...] >>> 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 45� phase shift with >>> the first capacitor (at the crystal frequency). >>> >> I am usually happy with around 1M. All it needs to do is to crank it >> over. Kaaaa-chum-pah ... POOF ... vrooooom. Unless I must start it >> really fast for some reason but that can require special kicker circuitry. > > Huh? You and I are talking two different resistors. I'm talking the > series drive resistor; you're talking the DC loop resistor. > Ok, different thing. Mostly you can get away without although that's not always the nice way of doing things. > Which brings to mind... does the CD4060 have the DC loop resistor > built-in? It would appear not. > AFAIR not. > And I should pay closer attention to details :-( The OP has 100K > there... needs to be 10-20Meg. > I usually go for 1M. 10M may not work outdoors when humidity is high and some condensation occurs. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jim Thompson on 14 Mar 2010 13:03
On Sun, 14 Mar 2010 09:51:52 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Jim Thompson wrote: >> On Sun, 14 Mar 2010 09:05:27 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> Jim Thompson wrote: > >[...] > >>>> 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 45� phase shift with >>>> the first capacitor (at the crystal frequency). >>>> >>> I am usually happy with around 1M. All it needs to do is to crank it >>> over. Kaaaa-chum-pah ... POOF ... vrooooom. Unless I must start it >>> really fast for some reason but that can require special kicker circuitry. >> >> Huh? You and I are talking two different resistors. I'm talking the >> series drive resistor; you're talking the DC loop resistor. >> > >Ok, different thing. Mostly you can get away without although that's not >always the nice way of doing things. > > >> Which brings to mind... does the CD4060 have the DC loop resistor >> built-in? It would appear not. >> > >AFAIR not. > > >> And I should pay closer attention to details :-( The OP has 100K >> there... needs to be 10-20Meg. >> > >I usually go for 1M. CD series stuff doesn't have a lot of gm. But 1Meg is good for something like 74HCU04. DO NOT USE buffered inverters for crystal oscillators! >10M may not work outdoors when humidity is high and >some condensation occurs. Mine are usually on-chip :-) ...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 |