Dark Sensor [Very Simple]

[ino]

Hi guys. I'm just new in this forum and it seemed that your 'simple' here are still complicated for me.

I designed a veeery simple circuit to act as a simple dark sensor. But after I drew the schematic diagram based on the circuit I made, I can't seem to explain why my design worked.

I know it's a little weird, but could you please help me explain this diagram?
The diagram is100% coherent to my actual circuit so rest assured the diagram works.

In the circuit:
_9V Battery
_360Ω Resistor
_10KΩ Potentiometer
_LDR
_LED

Thank you in advance.

 

[Nigel Goodwin]

Sorry, but there's no way that is going to work - for a start a 360K resistor feeding an LED isn't going to work.

Why not just design it properly?.

 

[ino]

Sorry but I really don't have an idea. Upon surfing the net, I just come across dark sensors using relays and transistors. But my aim in this circuit is a dark sensor using only the concept of op amps.

Can you suggest something? I really can't picture this out, I'm totally a newb.

 

[ericgibbs]

Hi guys. I'm just new in this forum and it seemed that your 'simple' here are still complicated for me.

I designed a veeery simple circuit to act as a simple dark sensor. But after I drew the schematic diagram based on the circuit I made, I can't seem to explain why my design worked.

I know it's a little weird, but could you please help me explain this diagram?
The diagram is100% coherent to my actual circuit so rest assured the diagram works.

In the circuit:
_9V Battery
_360Ω Resistor
_10KΩ Potentiometer
_LDR
_LED

Thank you in advance.

hi,
The 360K on the circuit diagram is shown as a 360Ω on your parts list, which have you used.?

What is the OPA.?

 

[ino]

I used the 360 Ω. Sorry for that.

Any idea?

 

[ericgibbs]

I used the 360 Ω. Sorry for that.

Any idea?

Hi,


What is the OPA.?

Is your circuit wired like this .?

 

[ino]

What do you mean by OPA?

Gosh, I'm totally a novice.

 

[ericgibbs]

What do you mean by OPA?

Gosh, I'm totally a novice.

Its the operational amplifier [that triangle] in the circuit drawing.

 

[ino]

Is your circuit wired like this .?

Uhm, what did the blue line mean between the potentiometer and the LED? Is it already open?

 

[ericgibbs]

Uhm, what did the blue line mean between the potentiometer and the LED? Is it already open?

WHAT IS THE AMPLIFIER.?

 

[ino]

Its the operational amplifier [that triangle] in the circuit drawing.

it's an LM741 Op Amp.

 

[ericgibbs]

it's an LM741 Op Amp.

hi,
I cannot find any data on a LM41, can you recheck the number.?

 

[ericgibbs]

it's an LM741 Op Amp.

Hi,
OK.
741 amplifier.

The circuit you have drawn will latch up and not work.

Do you want to work it out yourself or do you need help.?

Hint: its the connection from pin6 going back to the 10K pot thats the problem.

The Blue line on the 10K pot is to show the pots wiping contact, you had connected in an unusual way.

 

[ino]

hi,
I cannot find any data on a LM41, can you recheck the number.?

It's an LM741 Op Amp.

 

[ericgibbs]

It's an LM741 Op Amp.

I have seen your EDIT,
Look at my last post.

 

[ino]

Hi,
OK.
741 amplifier.

The circuit you have drawn will latch up and not work.

Do you want to work it out yourself or do you need help.?

Hint: its the connection from pin6 going back to the 10K pot thats the problem.

The Blue line on the 10K pot is to show the pots wiping contact, you had connected in an unusual way.

Well, I think I need help. This was just supposed to be a form of recreation, but then I found myself thinking of this problem for several days.

 

[ericgibbs]

Well, I think I need help. This was just supposed to be a form of recreation, but then I found myself thinking of this problem for several days.

hi,
Look at this very basic circuit. You may have to increase the value of R1 to something higher, say 47K or 100K , depends upon the LDR.

Set the 10K pot to the centre of its rotation at the start and carefully adjust for light/dark.

Get that part working and come back and we will add the rest. OK.

 

[ino]

hi,
Look at this very basic circuit. You may have to increase the value of R1 to something higher, say 47K or 100K , depends upon the LDR.

Set the 10K pot to the centre of its rotation at the start and carefully adjust for light/dark.

Get that part working and come back and we will add the rest. OK.

I'm already working on the circuit. What would be the effect if I don't get to replace R1 with a resistance higher than 10k? You see, 10k is my largest resistor here.

 

[ericgibbs]

I'm already working on the circuit. What would be the effect if I don't get to replace R1 with a resistance higher than 10k? You see, 10k is my largest resistor here.

Do you know what the dark/light resistance of the LDR is.?

 

[ino]

Get that part working and come back and we will add the rest. OK.

I already made the circuit. Its already working. Can you please explain to me the necessity of those corrections you made with my previous circuit?