[time-nuts] Squaring Tbolt 10Mhz output

Bruce Griffiths bruce.griffiths at xtra.co.nz
Thu Mar 24 18:10:46 UTC 2011


James Fournier wrote:
> My intention is to divide the signal by 10 and feed it as  an external
> frequency reference into my old HP counter. Hopefully this will increase
> it's stability.
>
> As for the circuits i have tried, there  have been so many. Most of them are
> variations of each other as i experimented on a breadboard. However, a few
> examples are the inverter and diff. amp. circuits from the wenzel site. The
> inverter (4049) produced a small .1vpp sine wave. The amp produced another
> sine wave of of basically the same magnitude as the input. I also replaced
> the inverter with a buffer (4050) and Schmidt trigger buffer. The buffer
> produced the same result as the inverter and the Schmidt produced no output.
> I tried some small signal diodes, can't remember the #, to try and rectify
> the signal and just got a high output. I tried a comparator LM339 (i think)
> and i got no response from the output.

The LM339 is far too slow for a 10MHz input among other things its 
output stage cannot switch fast enough, faster comparators such as the 
MAX999 and ADCMP600 series work well.

>   I tried everything with and without
> an input  capacitor (.1uf) and retried most of the experiments with a 10k
> pot between 5v and ground to replace the biasing resistors to allow a finer
> adjustment of the input.
>
> I have a feeling my problem is two fold: small signal with the forward
> voltage drop of many of the devices i have tried and the speed of the
> signal. I'm not sure everything can handle the 10Mhz signal.
>
> On Thu, Mar 24, 2011 at 7:42 AM, Bob Camp<lists at rtty.us>  wrote:
>
>    
>






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