Electronic help pls!

[Mr Sandman]

Hi chaps,

i have an LM335 and an LM10 to scale the output of the LM335 from 2.4v at 0c and 3.4v at 100c to 0v at 0c and 5v at 100c. There are some sugested circuits out there -

is i am having trouble interpreting it to make sense to me...ie what is the item to the right of the word sensor, is it a capacitor? if it is what value is it and what pin on the LM10 does it go to?

also, the arrow pointing down with the number 4 on it, do i tie this to 0vdc and to pin 4 on the LM10?

Thanks for the help chaps!

Steve

[Scott M]

That's not a particularly good diagram. The item is a 0.2v voltage source (it's a battery symbol.) It'd be the work of a minute to find the pinout of the chip and identify the pin number it's feeding.

[Mr Sandman]

having trouble figuring it out! And how do i work out how to get 0.2v from the 5v i have handy?

steve

[Andrew Gabriel]

It's a .2V voltage reference - in effect, it's a 0.2V battery. It's built in to the chip, which is why there's no pin number. The circuit is relying on the known drift of this reference voltage with temperature. (The data sheet I looked at only has it linear up to about 85C, not 100C.)

Yes.

[Tabby]

The 0.2v is best supplied by 2 resistors and a capacitor. +5v to resistor to a 2nd resistor to ground. And a nice big capacitor from the junction of the Rs to ground. Connect that junction to the +input of the opamp. Looks like the author had an oops I forgot moment.

The 2 Rs forma voltage divider, so the 1st one needs to be 25x the R value fo the 2nd one.

Which pin is the + input? google datasheet LM10

NT

[Tabby]

Makes more sense :)

NT

[Mr Sandman]

oooooooooookkkkkkkkk.............so do i just ignore the battery bit then as its built in?

Tar!

Steve

[John Rumm]

Not sure why they have drawn it in the circuit diagram since it would appear to be an internal voltage offset source.

According to data sheets:

on pin 4

Yup looks like it.

[Man at B&Q]

24x

MBQ