Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
One way to calculate the values for the string is to start with an arbitrary total series resistor value for the string (say 10kΩ) and calculate each resistor value to give the required comparator trip voltage, starting from the bottom using the "The Potential Divider Circuit" equation.
For the required resistor in series with the LEDs you just Ohm's law to give the required maximum 15mA LED current.
Thanx for help, but I am still confused. I don't know what should happend at the end. Voltage rise from temp sensor and as V rise it lights up LEDs.Isthis the idea?
This mean that resistors r8 r9 r10 must have resistances at certain fixed rate change so that it allow certain voltage only to pass to LED. why do we need the rest of resistors?
If temperature sensor is voltage source why do we need extra voltage sources at the top?
P.S. We did not study amps yet, I understand they just to strengthen the voltage. Does that mean that resistors r4 r3 r2 r1 should change by fixed rate.
No. The power supplies must have their negative connection go to common (ground).
U1 is not a linear amplifier, it is a comparator. The output is on (high) when its plus (+) input is more positive then its negative (-) input, and its output is off (low) when its plus input is more negative then its minus input.
Ok, I understood that I need to calculate this schematic according to voltage changes in lm 335 due to temperature changes.
Only problem is no matter how much I read documentation on lm335 ( http://www.electro-tech-online.com/custompdfs/2012/03/lm135.pdf ) I couldn't find where it says about voltage change per temp change...