1e7-divider-1.jpgYesterday I built a 10.000.000 divider with a small cascade of 74LS390’s to divide the rubidium 87 (Rb87) locked 10,000.000.00000(0) MHz from my Efratom FRS into 1 Pulse Per Second (PPS). I know that there is a another approach available. However, I managed to program a 16F648A PIC, but the contrapsion did not work. Perhaps the code needs a 16F84.
But… I am more into hardware anyway.

I built the divider on a small piece of epoxy bread board and combined my frequency standard with an “is locked, PPS works, and ready to use”-indicator. Thus, when the standard is switched on, several minutes later the PPS led starts to flicker.

The divider is depicted on the right (click to enlarge).

The PPS is shaped by a one shot generator (LS123) and the PPS width is approx. 75 ms.

A PDF of the -straight forward- schematic diagram can be downloaded here.

An advantage is that the PPS error is reduced by several orders.

This is a picture of the divider built into my Rubidium standard.

So, my Rb standard will now produce a ‘rock solid’ 1PPS for ntp.remco.org !