Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

pic16f87a input voltage

Status
Not open for further replies.

kta22

New Member
Hi everyone, i am using a pic16f877a to read analog signal from fuel level sensor (car) with 12v-14.4V maximum voltage. The code it's working well from 0-12v signal from sensor, but how i can reduce the input voltage if is around 14.4v to 12v without affecting the 0-12V voltage? In a few words i would like to reduce maximum voltage (14.4V) to 12V but 0-12V voltage to fluctuate the same (in order to not affect the source code ).I am trying to use a zeener diode(12.1v) but this is affecting 0-12v(and the source code too) with his 0.8V voltage drop. Can anybody help me with a schematic in order to resolve this problem?
thanks, kta
 

ericgibbs

Well-Known Member
Most Helpful Member
Hi everyone, i am using a pic16f877a to read analog signal from fuel level sensor (car) with 12v-14.4V maximum voltage. The code it's working well from 0-12v signal from sensor, but how i can reduce the input voltage if is around 14.4v to 12v without affecting the 0-12V voltage? In a few words i would like to reduce maximum voltage (14.4V) to 12V but 0-12V voltage to fluctuate the same (in order to not affect the source code ).I am trying to use a zeener diode(12.1v) but this is affecting 0-12v(and the source code too) with his 0.8V voltage drop. Can anybody help me with a schematic in order to resolve this problem?
thanks, kta

hi,
How are you connecting the 12.1V zener into the existing circuit.?
Do you have a simple diagram to post.
 

ericgibbs

Well-Known Member
Most Helpful Member
This is the schematic

hi,
This is a simple approx 12V clamp. [ you could use a 10V zener in series with two diodes to replace the 12V zener]

If you require a 'tighter' clamp voltage, you could use a comparator.

BTW: as this 33k/22k potential divider is connected to a 16F adc input, the impedance exceeds the recommended limit of 10K max.
 

Attachments

  • AAesp01.gif
    AAesp01.gif
    22.8 KB · Views: 201
Last edited:
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top