reduce circuit requirement voltage

[dexmonata]

hello guyz...

i'm still new in this field and need some help from u all...

i had a sample circuit that written 5volt dc suply...

my question is:

1) is it possible to adjust the circuit to make the input voltage become lower..since i might want to use battery sources for this circuit..let say 3volt..

2) if can..wht component should i add to make the input voltage is only need 3volt


i'm sory if my question seems relly stupid..but i need to know...

 

[LvW]

OK, I see. The name of your circuit is "sample circuit".
I just had a look in about 23 textbooks but couldn't find this circuit. Sorry.

 

[dexmonata]

i'm sory...

the circuit is attached below..it is humidity sensor circuit...

so..back to my question..is it possible to do it???

 

[IanP]

TLC555 should still work all right with voltages below 5V but the LM2904 has to be replaced with something like LMV358, which is the lower-voltage, rail-to-rail version of the LM358 (similar gizmo to the LM2904) ..
**broken link removed**

Rgds,
IanP

 

[dexmonata]

ok...so..i juz replace the lm2904 only rite???

is it other components still remain as diagram....

and then if i apply 3 volt dry cells to this circuit...can it give output voltage as if apply 5volt??

since this circuit is voltage output circuit...it vary with humidity...

 

[IanP]

You may need to reduce the gain of the output opamp (R7 & R9) to accommodate for the re-scaling from 0-5V to 0-3V, but that should become clear when you'll try to calibrate the whole thing ..

Rgds,
IanP

 

[dexmonata]

owh yeah..dats true...

is there any other dual op amp dat need low voltage suppy???

i am afraid that lmv358 is not availble in my country since last tym i check..only few dual op amp is avlble...

 

[karesz]

Hi dex,
you knows what kind of dual OPs are to become for you, it will be more simple to note their types and search for datas of that group
Or do a list here upload of their...
K.

 

[dexmonata]

i alredy build dat circuit in multisim and try to simulate it...

but da result is...i got negative voltage:?:

can some1 help me figure out this problm......

supposely i should get the result between 2V to 5V...

 

[dexmonata]

Hi dex,
you knows what kind of dual OPs are to become for you, it will be more simple to note their types and search for datas of that group
Or do a list here upload of their...
K.

yeah..i will try ask again the local shop about the dual op amp...

thanx 4 da advces..