Thread: need help for mcs51 and ADC0808

Originally Posted by dzakriel

hi I'm a new member here

I need advice about how to manage a ADC0808 as a general ADC IC
because i have a final task to make a teaching aid for mcs51 using ADC0808
as i know ADC0808 has several input and output.

I still can't put it general enough i even confuse when reading the data sheet

please be patient when help me
thank you

hi,
How many channels on the ADC do you want to use.?

Originally Posted by dzakriel

if possible i want it all
I need to make it as general as it is

but first may be i only need one
i need to convert form LM 35 temperature sensing
to binary
as first trial that's good enough

hi,
Ok, I'll post a circuit tomorrow.

A point to understand is that the LM35 is 10mV/Cdeg, so that means a max of 1V at 100Cdeg.
The ADC is 8bit [255] so the resolution will be about 1Cdeg.

Originally Posted by dzakriel

it's correct
the LM 35 have resolution 10mv/cdeg and max 150 c deg, so it will be 1.5V.
thats why i use OpAmp to aplify it to 5V

but since I didn't know the limit current for LM 741 noninverting input and the max output current of LM35 I only use a potensio at the output of LM 35 before input noninverting in LM741.

these circuit suppose work in proper, after i find out the ideal resistance to sync LM 35 with LM 741 I 'll definitly exchange the potensio with fix film resistor, later.

Thanks for the support
it worth much for me

What power supply voltages will the 741 have.?

Originally Posted by dzakriel

I use ordinary two Power supply with +15 1 A and -15V 1 A

did i need to increase the current supply?

hi,
Power is OK.

Look at this datasheet, pages 12/13, it gives a number of MCO to ADC examples,