[sdiy] strange behavior from an ADC

[Dan Snazelle]

Ok

i hate to keep asking questions but I think now I have no choice.

The ADC I am using is an ADC0808

It is supposed to take a REF of up to 5volts and a neg volt ref of Grnd.

The VCC is 5volts.

But here is where things go weird.

I built up a few peoples level shifter circuits to try and get to the bottom of my problems. 

So i ended up with a perfect signal that was in between 0-5.

i got nothing.

So i decided to play it safe and hook up a pot between 0 and 5 volts and put it through a 1k resistor into the input
of the ADC


I got nothing!

So i decided to plug the same pot into 10v to grnd

Well guess what...The ADC only seems to KICK IN (or respond) between around 5.1 volts all the way up to 7 volts.

faulty chip?

what the heck could be going on?

This does explain all the problems I was having though.

BTW...my 5 volts is coming from a reference and it IS putting out 5volts.



any help appreciated


Thanks