[time-nuts] minimalist sine to square

Jerry Hancock jerry at hanler.com
Sat Jan 20 14:43:40 EST 2018

Tom might have started this as I was playing around with PICDIV and had asked him the best conditioning circuit.  Turned out I had all the parts to copy the TADD-2 including the mini circuits transformer so that’s what I did.  It works well, pretty sensitive, etc.  I’ve also used the bias trick with a TTL or CMOS buffer when I needed to convert SPIDF signals to baseband for driving an optical connection.

Now that I had the input conditioned, I need to drive a 50ohm load with the signal coming from the PICDIV.  Can someone point me at a circuit using transistors and 10V if possible?

I am trying to duplicate one channel of the TADD2 so I can bring 10Mhz down to 10Khz.



> On Jan 20, 2018, at 11:21 AM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
> --------
> In message <eb956eca-4534-0463-031b-232f8bdbd62f at earthlink.net>, jimlux writes:
>>> I played with that, I used a small transformer to balance the signal
>>> and then into LVDS receiver through a voltage divider.  Worked well,
>>> but I didn't measure the jitter, it was just for a micro-controller.
>> You can also do it with capacitive dc block to one side, and some 
>> resistors - the ap notes describe it.  The receivers are a fairly high Z 
>> input, so you pick the voltage divider resistors to make the termination 
>> resistance right for the incoming signal.
> Yes, but that doesn't give you galvanic isolation, which I think is almost
> mandatory unless it is a metrology situation.
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe    
> Never attribute to malice what can adequately be explained by incompetence.
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