MN3101 math

[puppiesonacid]

well, i guess by that logic no questions should be asked so long as you already know the answers

It's a common problem.

There's no way the Lancaster book will know about 35 k ohm at the input of the MN3101 gate!   I was surprised to see such a high value myself.

true, its a different way of coming up with a clock driver, if i get what he means. I'm just focusing on the MN3101. so I appreciate the info and helping understand.

[Rob Strand]

its a different way of coming up with a clock driver, if i get what he means. I'm just focusing on the MN3101. so I appreciate the info and helping understand.

On p269 there's a bit of explanation about that type of oscillator and it explains why you add the second resistor.
On p271 there's a formula but it only applies to the simple case of R1 large, like the National semiconductor pic I posted earlier.

There's nothing wrong with using those simple formulas as a ball-park figure provided you don't expect them to produce exact results.    Simple formulas can be off by 50%.

Most oscillators will end-up lying in the region of T = RC and 16*RC.   The digital ones are more likely to be T= RC to 4*RC.   You can bash out some numbers without doing any analysis then tweak the values with some measurements.   Normally I try to do all the accurate calculations because I like to know where I stand.  If something doesn't match-up it could mean something is wrong.