i would like to know if there's a difference between LMC555 and NE555, or something that is CMOS type 555, i built this circuit from EME systems, SMX soil moisture interface but it didn't work, the electronic shop here sells only NE555, pls help, thanks a lot

 

Can you google and find the data sheets?

 

The LMC555 is a CMOS version. It can operate at lower voltages than the NE555 does, and the output is able to reach nearly to both power rails (+V, GND).

The NE555 needs around 5v to operate, but some circuits won't work with a supply that low, particularly if the timing capacitor is being charged/discharged by the output (pin 3).

Post the schematic of the circuit, that is the quickest way to get help.

 

http://www.emesystems.com/pdfs/SMX.pdf

 

Sorry, it's not going to work on 3.3v with an NE555.

Are you in the USA? If there is a Radio Shack store nearby, they usually have TLC555 timers in stock. Don't let them sell you anything else, as a standard NE555/LM555/SE555 won't work.

 

thanks a lot, im goin to look for a cmos type 555, i analyzed the circuit several times but can't look on some errors, its clear now that a standard NE555 won't substitute the cmos type, thanks a lot, more power