pic to detect voltage change - Electronic Circuits Projects Diagrams Free

max_imum2000 · 10th November 2006, 01:11 AM

hello
i am trying to make a pic detect a small voltage change 0.2v to 0.6 volt
not measure it , just detect its change
i have to use 16f628, anything else is not an option
any suggestions ?

Marks256 · 10th November 2006, 01:15 AM

Analog to Digital converter, maybe?

Pommie · 10th November 2006, 03:22 AM

Check out the comparator and voltage reference sections of the data sheet. You can set Vref to 5/24 * 2 = 0.4V and use a comparator to detect if the other input is above or below it.

Mike.

akg · 10th November 2006, 04:26 AM

as already suggested use the internal comparators

kamdy · 10th November 2006, 10:25 AM

I think it is better to amplify the voltage 10 times using low noise operational amplifier such as TLO71 to get greater ampltude and and then use a window comparator to detect the change of the voltage

**Nigel Goodwin** · 10th November 2006, 10:35 AM

Quote:

Originally Posted by kamdy

I think it is better to amplify the voltage 10 times using low noise operational amplifier such as TLO71 to get greater ampltude and and then use a window comparator to detect the change of the voltage

Regardless of amplifying it or not, it makes obvious sense to use the internal comparators in the PIC - there's also no requirement for a window comparator, as he's not looking to detect a 'window', just above or below a certain value.

max_imum2000 · 10th November 2006, 10:42 AM

thanks all
i know about using an opamp
but actually i am trying to minmize the use of components

so is it possible to just connect the source to the input pins of the comparator and set the Vref. and thats it
with no amplification or whatever ?

kamdy · 10th November 2006, 11:13 AM

what is the maximum voltage of ths source you are using

**Nigel Goodwin** · 10th November 2006, 11:54 AM

Quote:

Originally Posted by max_imum2000

thanks all
i know about using an opamp
but actually i am trying to minmize the use of components

so is it possible to just connect the source to the input pins of the comparator and set the Vref. and thats it
with no amplification or whatever ?

Read the datasheet about it!, there are low and high ranges for Vref, the low range covers from 0.2V to about 3V in 0.2V increments.

Pommie · 10th November 2006, 12:49 PM

Quote:

Originally Posted by max_imum2000

thanks all
i know about using an opamp
but actually i am trying to minmize the use of components

so is it possible to just connect the source to the input pins of the comparator and set the Vref. and thats it
with no amplification or whatever ?

just do as I said earlier.

Mike.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Latest
Voltage	ElectroMaster	Electronic Theory	44	8th August 2007 05:35 PM
measuring transconductance(gm)	walters	General Electronics Chat	24	6th February 2006 08:49 AM
Voltage reference with a zener diode	Futterama	General Electronics Chat	7	28th January 2006 08:35 AM
12vdc -> 7.5vdc transformer	gulaz	Electronic Projects Design/Ideas/Reviews	10	7th May 2004 07:59 PM
Accurate low voltage diff measurement	Oznog	General Electronics Chat	3	3rd May 2004 04:41 AM

10th November 2006, 01:11 AM	(permalink)
max_imum2000	pic to detect voltage change hello i am trying to make a pic detect a small voltage change 0.2v to 0.6 volt not measure it , just detect its change i have to use 16f628, anything else is not an option any suggestions ?

10th November 2006, 01:15 AM	(permalink)
Marks256	Analog to Digital converter, maybe? __________________ There is no "I" in "team", unless Apple makes it... Then it would be iTeam.

10th November 2006, 03:22 AM	(permalink)
Pommie	Check out the comparator and voltage reference sections of the data sheet. You can set Vref to 5/24 * 2 = 0.4V and use a comparator to detect if the other input is above or below it. Mike.

10th November 2006, 04:26 AM	(permalink)
akg	as already suggested use the internal comparators __________________ Gods own Country Incredible !ndia www.flickr.com/photos/_akg/ "Give a man a fish, and he will eat for a day. Teach that man to fish, and he will eat for a lifetime."

10th November 2006, 10:25 AM	(permalink)
kamdy	I think it is better to amplify the voltage 10 times using low noise operational amplifier such as TLO71 to get greater ampltude and and then use a window comparator to detect the change of the voltage

10th November 2006, 10:42 AM	(permalink)
max_imum2000	thanks all i know about using an opamp but actually i am trying to minmize the use of components so is it possible to just connect the source to the input pins of the comparator and set the Vref. and thats it with no amplification or whatever ?

10th November 2006, 11:13 AM	(permalink)
kamdy	what is the maximum voltage of ths source you are using