Electronics > Beginners
Schmitt disappointment
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PerranOak:
Excellent, thank you all.

There is a 100nF cap near-ish to the supply pins but the pins are on the diagonal opposites of the chip - mental! What would be a low ESR? My one has ESR = 15Ohms but I have no way of measuring the inductance of it.

How do you know what the impedance of the co-ax is? Is it as simple as measuring it in the normal way?

Cheers.
wraper:

--- Quote from: PerranOak on October 04, 2018, 04:22:43 pm ---My one has ESR = 15Ohms but I have no way of measuring the inductance of it.

--- End quote ---
It's useless to measure ESR of ceramic capacitors. At 100 kHz you won't get any meaningful figure.
Mr. Scram:
Why do many chips have power and ground on opposite sides of the chip? Isn't that exactly what you don't want from a loop area point of view?
Zero999:

--- Quote from: Mr. Scram on October 04, 2018, 06:31:40 pm ---Why do many chips have power and ground on opposite sides of the chip? Isn't that exactly what you don't want from a loop area point of view?

--- End quote ---
It's probably a relic from back when decoupling wasn't essential. Many of the older CMOS ICs, such as the CD40106 will work perfectly with little or no decoupling capacitors.
StillTrying:

--- Quote from: PerranOak on October 04, 2018, 04:22:43 pm ---There is a 100nF cap near-ish to the supply pins but the pins are on the diagonal opposites of the chip - mental!
--- End quote ---

On a breadboard I use a 100n with leads long enough so that the cap is above the IC, the breadboard's power lines are too many connections and uHs away to supply power for ns edges.  :)
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