its a shame i cannot post the picture i took is there any way to be able to send my oscilloscope picture its 800k thats the problem
On Mon, Nov 28, 2011 at 7:29 PM, Michael Malloy <[email protected]> wrote: > On Mon, Nov 28, 2011 at 7:14 PM, Michael Malloy <[email protected]> wrote: >> yeah it is squaring up, but not great I have already designed the >> circuit boards, hmm >> maybe if i replace the 74HC04 with a 74HC14 (schmitt trigger input) >> which I do not have >> I did make a surface mount single gate schmitt trig after the 74HC04 >> as I knew that >> this squares things up much better, however after the 74HC04 it goes to >> a 74HC4040 divide by 12 counter and from that input it goes to another >> 74HC04 into the processor >> I am worried that the fact that the counter and the processor are 90 >> degrees out of phase clock cycle >> if I put the single gate schmitt trig in it will bring both in phase >> I may need to make software adjustments if this happens?? >> >> and no I did not test the unit without any load, I had a hombrew TCXO >> in the original >> circuit but its performance was only +- 10PPM and caused problems with the >> codec >> its a very sensitive design to jitter, TXCO was cheapest option but if >> I had the money would have put an OCXO >> in but they are not cheap in small runs, I am getting off track >> I will take a picture of my oscilloscope and post it >> >> let me see if the 74HC14 is pin for pin compatible with 74HC04 maybe I >> will replace with this. >> but I do not think I have any here >> >> On Mon, Nov 28, 2011 at 6:36 PM, Attila Kinali <[email protected]> wrote: >>> On Mon, 28 Nov 2011 16:15:37 +1100 >>> Michael Malloy <[email protected]> wrote: >>> >>>> Hi all I ordered a 8.192MHZ TCXO 1.0PPM >>>> Now it was supposed to have a clipped sine wave output? however it >>>> looks more like a saw tooth, I assumed a clipped sine would be a sine >>>> wave with the peaks clipped, I am running this through >>>> a 150pF cap and then using a inverter amplifier i.e. 74HC04 with a 1M >>>> resistor from input to output. >>>> >>>> am I over loading or loading down the the oscillator, or should I be >>>> changing the buffer capacitor? >>>> I mean the circuit is working but its not 45/55 duty cycle >>>> the out put looks like the first 0 -90 degrees of a sine wave then >>>> drops to zero stays there for about 20% of the duty cycle then ramps >>>> back up? >>> >>> Do you measure the TCXO raw, w/o any circuitry attached? >>> Because this sounds rather like that the 74ZHC04 is messing >>> with the signal. Maybe the 1M resistor isnt really 1M? >>> >>> Other than that, i would feed the output directly to >>> a 74HC14 (schmitt trigger input) to square it. If you >>> want to have precise or adjustable duty cycle, you can also >>> use a comparator (but make sure to include enough hysteresis, >>> otherwise the comparator might oscillate) >>> >>> >>> Attila Kinali >>> >>> -- >>> Why does it take years to find the answers to >>> the questions one should have asked long ago? >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> >> >> >> -- >> #include <sig.h> >> /* ================ */ >> Michael >> /*How crazy does it get on the moon, when theres a full Earth?*/ >> > > > > -- > #include <sig.h> > /* ================ */ > Michael > /*How crazy does it get on the moon, when theres a full Earth?*/ > -- #include <sig.h> /* ================ */ Michael /*How crazy does it get on the moon, when theres a full Earth?*/ _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
