14-08-2016, 01:10 AM
I need working of dark sensor using LDR and LM324 ,no transister used.
The LM324 is a 14 Pin dual in-line Plastic Package chip which has four independent, high-gain, internally frequency compensated operational amplifiers (Op-Amp) designed to operate from a single power source. It is also possible to power this with 4 different power sources….One for each independent Op-Amp inside the chip. This chip can be used as a Power Amplifier , LED Driver , “BI-QUAD” RC Active Bandpass Filter , Lamp Driver , Pulse Generator , Square wave Oscillator , Driving TTL , Low Drift Peak Detector , zero crossing detector and many more. Here is what it looks like inside:
LM324_pinout_small.jpg
It can accept a very wide power supply range from 3v – 32v. Since it allows up to 32v for power input, I am thinking how this will work as a 12v battery minder. For now we will make a simple circuit so that when one voltage exceeds another it will light an LED. You can use this exact circuit for a night light or dusk to dawn lighting.
LM324 – 14 Pin IC with 4 separate Op-Amps inside.
10k Potentiometer – I am actually using a 10k Trimmer Pot so that I can make fine adjustments to the voltage. If you dont have one, just just a reguler 10k Potentiometer. I Used to set our comparing voltage
LDR (Light Dependent Resistor) – This voltage will change based on the light and the input voltage. The more light hitting the LDR, the less resistance there is going through it. I am using 5v so it will vary between 0v and 5v. The LDR is not polarized and it does not matter how you hook it up. This is different from an LED which has a positive and negative side.
5mm Red LED – Used as our indicator when the LDR meets or exceeds the voltage set by the 10k Potentiometer.
10k Ohm Resistor – Brown, Black and Orange band. This will be used on the LDR and will go from one pin to positive.
100 Ohm Resistor – This will go from Pin one, which is the output of the Op-Amp we will be using inside the chip, to the positive side of the LED.
Misc. Hook-Up Wire – Used to make connections between the components on the bread-board.
Power Source (9v Battery with 5v Regulator is what I am using). If you don’t want to make the 5v regulator, you will need to change the value of your resistor to a 220 Ohm resistor.
MultiMeter - You will need this to read the voltages in two places on this project.
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The LM324 is a 14 Pin dual in-line Plastic Package chip which has four independent, high-gain, internally frequency compensated operational amplifiers (Op-Amp) designed to operate from a single power source. It is also possible to power this with 4 different power sources….One for each independent Op-Amp inside the chip. This chip can be used as a Power Amplifier , LED Driver , “BI-QUAD” RC Active Bandpass Filter , Lamp Driver , Pulse Generator , Square wave Oscillator , Driving TTL , Low Drift Peak Detector , zero crossing detector and many more. Here is what it looks like inside.
LM324 – 14 Pin IC with 4 separate Op-Amps inside.
10k Potentiometer – I am actually using a 10k Trimmer Pot so that I can make fine adjustments to the voltage. If you dont have one, just just a reguler 10k Potentiometer. I Used to set our comparing voltage
LDR (Light Dependent Resistor) – This voltage will change based on the light and the input voltage. The more light hitting the LDR, the less resistance there is going through it. I am using 5v so it will vary between 0v and 5v. The LDR is not polarized and it does not matter how you hook it up. This is different from an LED which has a positive and negative side.
5mm Red LED – Used as our indicator when the LDR meets or exceeds the voltage set by the 10k Potentiometer.
10k Ohm Resistor – Brown, Black and Orange band. This will be used on the LDR and will go from one pin to positive.
100 Ohm Resistor – This will go from Pin one, which is the output of the Op-Amp we will be using inside the chip, to the positive side of the LED.
Misc. Hook-Up Wire – Used to make connections between the components on the bread-board.
Power Source (9v Battery with 5v Regulator is what I am using). If you don’t want to make the 5v regulator, you will need to change the value of your resistor to a 220 Ohm resistor.
Making it Work
Now, here is where the real magic comes in. Since we are going to be comparing two voltages, we need to get a voltage to compare against. Basically our 10k Potentiometer will be set to a certain voltage. If the voltage from the LDR (remember, it will vary its resistance depending on the amount of light on it) meets or exceeds the voltage set on the 10k Potentiometer, it will allow the output to go “high” and light the LED. If the voltage from the LDR is below the set voltage on the 10k Potentiometer, the output is “low” not allowing any voltage out to the LED.
To do this we will need a multi-meter to measure voltages in two different places. The first voltage reading we will take is from the LDR in whatever lighting environment you require.
So, using your multimeter, make sure it is set to the volts DC setting and on the 20v setting which should be plenty for what we are doing. Make sure the red probe is plugged into the “MA” port and not 10A. Plug the black probe into COM. Take the Black probe and attach it to ground on the bread-board (which is the blue line on either side of the bread-board). Take the red probe and attach it to pin 3 on the LM324. This is the voltage coming in from the LDR. If the amount of light you need is where you want it, note the voltage reading on your multimeter. Remove the red probe and then do it again at the same point just to verify the voltage. The voltage will measure between 0v and 5v if you are using a 5v power source. Write down that voltage reading as we will use it to set the 10k Potentiometer.