12F629 LDR - Light Dependant Resistor

[Dennis]

Here it is .. the schematic corrected to show +5V and GND rails :-)

Kind regards
Dennis

[BobK]

Hi Dennis,

So you have an LDR and a pot and a 1 k resistor across the supply rails. Isn't this combination suppose to connect to an input on the micro? I mean how else is the micro suppose to sense a change then turn the LED on?
Just an observation!

BobK

Nice program example though!

[Bruce]

Wiper on POT to GPIO.2..?

[grounded]

forgive just trying to understand what your doing here.
instead of using the LDR as a A/D input (which the 29 does not have)
when the amount of light causes the voltage to over come the the pull down resistor you get a high input on gpio.2 ?
am I close?

[Dennis]

Hi all

Apologies for the confusion .. I had left an important line out of the schematic in my rush to share.

All is fixed now !! The new corrected schematic is attached.

I don't know how those bad schematics got here ..HUMAN HUMAN HUMAN.. grrr!

@BobK .. well we could have been trying a current limiter or 'floating points' ;-)
Valid chirp though was laughing like mad at myself for forgetting a track in schematic and spot on it should connect somewhere for the PIC to be of any use ...!

@grounded , damn right... build it , and see the magic ;-), works like a charm!

@Bruce GPIO.2 conects right between the 10K potentiometer and the LDR

Build it build it build it !

Kind regards
Dennis

[Bruce]

I used a similar circuit for an Intel 8749 Micro-Bot project I wrote for Circuit Cellar way back
in 1998, issue #92, to turn on a set of bright LED headlights on my robot.

Worked really well. Robot entered a dark area, and headlights turned on automatically.

Moved into the light, headlights turned off.

http://www.circuitcellar.com/archive...ents/1998.html

Déjà vu ehh...;o)

[Dennis]

Hi Bruce


Unfortunately I can't get to see the article/place/page referred to in your link as I am not a subscriber :-(
Looks like a very interesting magazine(s) based on the tables of contents!
I always used to read Elektor magazine which aslo had some very interesting articles and projects.
Would be very interested to have a look though.. perhaps you could show a schematic or code ?

What got me started on the LDR mission was this site http://www.doctronics.co.uk/ldr_sensors.htm as I needed to understand the working of LDR's.

Earlier today I was wondering what would happen if(and when) the supply voltage would drop below the 5Volts I was using for calculations.
Need to dabble a little bit more by dropping the supplied voltage and see what the results are, hope to be able to give some feedback on that shortly.

Kind regards
Dennis

Kind regards

Dennis