Looking for two-input comparator with hysteresis

Only one resistor in series ( as part of the PD ) is needed between the schmitt input and the transformer connection. Since the voltage now aonly goes about 1V below ground and with the potential divider helping you also won't need a series diode.

Graham

No. No additional connection is required. The power supply provides the return part of the siganl path.

Graham

An R and a cap are a filter not a PD.

And the schmitt is running of how many volts ? 5 ? The job of the PD is to reduce that 10V to a voltage within the supply rails of the schmitt.

Actually, yout 12V ac winding will produce about 17V pk-pk so a PD of just greater than 3:1 should be used. Make that 100k into 330k and add a 100k from schmitt input to ground in parallel with the 22n ( this won't alter the RC time constant very much ).

Yes.

No.

No. Not required.

Graham

Graham

It's actually way more accurate than that. Remember that mechanically driven clocks with ac synchronous motors have to keep time too.

Graham

Now only the other week I asked if it's Schmitt or Shmitt and now you say Schmidt ! Come on which one is it now ?

Graham

And the UK tendency to prefer to overdesign too.

Graham

I still don't feel quite right doing it though. And for just *one resistor* extra.

Graham

Yep. Why use a 4x4 post when you have a Greek column handy ;-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

I'm pleased to see I'm in rarefied company ! It's just so *cheap* doing that too. ;-)

Graham

Exactly so. Unless a component has manufacturer specced data I'd avoid using it.

The cost of which will be what ? vs 0.1c for a resistor in qty adding $1 total BOM cost to a run of 1k pcs.

Graham

On a frequency dependent basis ! It's called a filter !

I advise you not to get into the habit of using incorrect terms. It could prove expensive in the long run and simply daft in the meantime.

No. A PD is quite specifically something else.

Graham

That accords with the last info posted on the subject here too.

Ta, Graham

They divide potential, don't they? The way they divide potential changes with frequency, making them a filter, but I would argue that they're a potential divider too.

Chris

According to Wikipedia the inventor's name was Otto H. Schmitt.

Chris

That's interesting. So two capacitors in series would be a potential divider, because the division of potential isn't frequency dependent?

Chris

How many seconds do they have in a minute?

John

Well, they usually do. TI specs +-20 mA for its HC14, with no footnotes about duration.

John

prove

Yes, that can indeed be done. It has another useful property. Capacitors don't dissipate energy so it's effectively lossless unlike a resistive divider.

Graham