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lidnariq wrote:Thanks for taking the time to explore this!

Naïve question: any idea why the free running frequencies not independent of the value of the missing crystal? The really visible outlier is no xtal/14.96MHz/10MΩ/220pF.

Are you asking in regards to the vast difference between the RC TC Res Frequency and the circuit's free-running frequency? This point has me very curious. For a single gate osc the RC should free run in the low KHz range for most these chosen values; I think with the added gates of the FF and associated Prop delays, the mode of operation is closer to the Ring Type Waveform Generator outlined at this site:
http://www.electronics-tutorials.ws/wav ... ators.html

OTOH, Are you asking about the odd free-running outputs for crystal group? In most cases the same RC combos in the different data sets are close, ~10% ( I essentially tested the same 12 combos 4 times), but a few reading aren't even close to the average.

For each test I changed/added/removed test components, so with the moving and handling of the breadboard, quite likely changed some of the stray C. Or RC oscillators at these frequencies are just very unstable.

For the one you quoted, I'm thinking it's a transcription error (I recorded the raw meter reading then went back through my notes transcribing them into the spreadsheet. Could have been my handwriting). Or my meter acting up, it seemed sensitive to the poor test point on the breadboard and the tip on my test lead.

With some of the others odd readings, such as the 11.525MHz xtal data set and 68pf cap. I reran these tests and tried another 68pf cap from the same batch. The best I can say is it could be related to the unknown specs of the xtal.

One thing that seems the most important to me is the upper limit to the C value at these frequencies. This appears to be unrelated to the TC of the combo, as other RC combos with a similar TC allow osc lock. The Patent suggests that the RC TC should be > 1/2 the period of the Xtal, which in all the test cases is true. So the questions remains how close to "1/2 the Period" is acceptable and what is the impact on that particular Xtal.

I've been trying to figure out a good way to graph this but there's four dimensions of input

That would be interesting. I wish my data set was larger though
Yogi

yogi wrote: Are you asking in regards to the vast difference between the RC TC Res Frequency and the circuit's free-running frequency? This point has me very curious. For a single gate osc the RC should free run in the low KHz range for most these chosen values; I think with the added gates of the FF and associated Prop delays, the mode of operation is closer to the Ring Type Waveform Generator outlined at this site:
http://www.electronics-tutorials.ws/wav ... ators.html

I was asking about the point you've attributed to the typo.

In Intro EE lab in college, we built a ring generator, and specifically played with the length of the wire on the long loop back. It was pretty easy to get enough inductance out of the aerial wire to get tens of volts on the input to the first inverter... In any case, I think you've got the right of it. There's no hysteresis at all with this circuit topology, the resistor just biases the inverter chain to its center point, so any oscillations we're seeing are propagation speed through the gates.

I guess it is useful because it gives us a likely upper bound on the crystal we can use, though. Not that there are all that many fundamental-mode crystals above 20MHz...

I went back through my notes in regards to the mentioned odd readings. The test procedure for each Xtal group was to insert the Resistor then run through the different Capacitors, taking the readings. For the 14.970MHz Xtal group I broke this pattern; starting with 68pf and then realizing that I had skipped the 22pf, ran that test last.
SO when I entered the data in the spreadsheet, the 14MHZ/5M set was copied out of order, Sorry guys
Here is an corrected xls; I also added the TC for each RC combo (very redundant, but handy for comparing different combos). Yogi

It's a me again. Will you make available boards with built in flash chips for discrete mappers like NROM, UNROM, etc.? How much $$$?Now that bunnyboy doesn't do repropaks anymore I think InfiniteNESLives is the only site with a reasonable new board solution. Plus it's way easier to program a new board with the Kazzo than desoldering old mask roms.

Sorry I missed your post Punch..

Punch wrote:Will you make available boards with built in flash chips for discrete mappers like NROM, UNROM, etc.?

Yeah I actually designed a separate 3rd version of my board tailored towards discrete mappers. There turned out to be a few hiccups found in the prototyping of greater than NROM designs. That kept me from releasing them on time with my original plans. I'll address the specific issues on that thread, but the good news is I've got the final design all laid out now and will be ordering the first production batch in the next week or two. That would put their sale available in June if all goes as planned.

How much $$$?

Good question. I haven't fully decided yet, they'll be comparable to the pricing of my other products. Notably cheaper than my CPLD full flash boards. I made those boards extra small in efforts to keep cost down and help offset the cost of providing a fully assembled flash board with no soldering required. I also plan to have significant tiered pricing to provide benefit to homebrew production.