[time-nuts] Input filter for data logger

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sun Nov 19 20:29:24 EST 2017


The performance of virtually all CMOS gate sine to CMOS converters degrades significantly once the signal at the gate input exceeds the supplies sufficiently to cause the input protection circuitry to conduct. This effect is very easy to measure with HCMOS.

Bruce 

> 
>     On 20 November 2017 at 14:20 Mark Sims <holrum at hotmail.com> wrote:
> 
>     Here are Wenzel's input circuits:
>     http://www.wenzel.com/documents/waveform.html
> 
>     The TAPR TICC uses a slightly modified version of the two transistor circuit.
> 
>     Also check out the LPRO-101 manual for their versions of the single CMOS gate squarer. One thing they do is add an RC filter to the CMOS gate power supply.
> 
>     I use this version (with a 74HC86 as the input gate) on my HP-531xx time interval calibrator circuit. Wenzel says an HC gate works better than AC logic if you don't need to handle higher freqs. It provides surprisingly good performance for such a simple circuit.
> 
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