reduce circuit requirement voltage

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dexmonata

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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...
 

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.
 

i'm sory...

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

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

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
 

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...
 

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
 

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...
 

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.
 

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...
 

karesz said:
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.
Click to expand...


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

thanx 4 da advces..
 

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