hi and hello to everyone...

i am after some help with a couple of circuits i want to make, first off i would like to make a bar graph circuit so that all the LEDs light up at a certain resistance from a water temp sensor, then as its gets warmer for the lights to go out one by one on different tempretures, do i need a LM3914 or LM3915 or LM3916? does anyone have a circuit for this or very similar please??

Also i would like to make a circuit for a tacho from a car, need a frequency to voltage convertor which will then go through one of the LM ICs (which one?) again anyone have a circuit for this?

thanks

 

hi

you can use the suggested circuits of National for your purpose. am also attaching 2 circuits not of my making but from another author.

oops sorry i forgot to include the circuit, here it is.

 

hi

thanks for that, i can only see one pic, so will the input on this circuit work for an adjustable resistance source ie from the temp sender unit and a voltage source from the tacho source?

 

hi

yes it can accept variable sources and if you intend to use LCDs as your display you use the 3915 or 3914, but if you like to use LCD use the 3916.

sorry for the other pic, i don't know what happend maybe i forgot. anyway here it is with some explanation.

 

thats great, thanks a lot..