I have two PCBs from a piece of defunct Nortel equipment with this oscillator. CMAC R2133 Freq 20.48 MHz. Looking at the circuitry around it, there’s a 16-bit DAC (AD7846), a 5V regulator (78L05) and a buffer (74F00). Google could not find me a datasheet, so I removed the oscillator to trace the pinouts (Nortel used the outside layers as groundplane, you will see nearly every trace goes from a component to a via. Makes it difficult).
Pin 1 is 0V, pin 2 is the output, pin 3 is 5V, and pin 16 is the control voltage from the DAC which is configured to supply 0-5V out via the 51R1 resistor R40 and a 47u capacitor C77. The output goes to pin 2 of the 74F00 via 33R2 R53.
I posted the above pic to Facebook, within an hour or two someone sent me the datasheet (well, the Nortel spec sheet, which is basically the datasheet in reverse). It is indeed a TCVCXO, pinouts as I’d already determined (pins 4-15 are N/C), giving -10 to -15 ppm with 0V on the control pin and +10 to +15 ppm with 4V on the control pin.
Stick this thing through an 11 stage binary counter and you get 10 kHz, add a PIC and a GPS and it could be the most accurate thing on your bench.
The next day the sun was out and we got a few better pictures.
We went to see the Plečnik library. For 5 euros per person, this is what you can see. The reading room, with NO BOOKS. Oh, and the staircase is also included as an attraction. NOT recommended.
Yea, we didn’t know either.
Anyway, the main point of Ljubljana was to go to the Friday market (which rained out) and to get a car. Ended up hiring a car from renti.si. They’re a bit bait and switchy in that you can’t book a car through their website, and their special (20 Euro / day for the 25 Euro / day cheapie if you take it for two weeks or more) is only available if you book it. So I ended up with the 25 Euro / day option. Which was still the best price out there.
The weather forecast told me that this Monday was going to have the best weather of the whole week, so I made a beeline to Jeruzalem, specifically lunch at the Gostišče Taverna. Recommended.
And from Jeruzalem it’s only a short trip home (where “home” = our Vikend in Globoka).
The rest of the week was kind of meh, weather-wise. We went to Varaždin for lunch and Ptuj for second-hand clothes (lots of second-hand clothes) and for the rest stayed in, made fire, cooked, and drank. Which is probably no different from what we would have done had the sun been shining.
Then for the weekend we went to Zagreb, and from there to Zadar and Pula, but that’s for a different blog post.