LM 324 Lamp Fader.....?

[Gayan Soyza]

Here is a lamp fader designed in LM 324.There are many op amp designs used to fade LED's.You may have experienced like this before.In the original circuit the R1 is directly connecting to pin7 (not via SW).

It starting from zero.The brightness is increasing smoothly & after it reaches to maximum brightness again its reducing to zero.

I added a SW near the R1 so when you press SW its changing the brightness level from zero to max & max to zero.

My ques is I need two switches one is to increase brightness other is to decrease.

Can anybody suggest a method for this without taking a microcontroller.

I have attached the Schematic.

Thankx.

 

[HarveyH42]

This circuit has been around for a while...
Need to do something with the unused opamps, but don't remember off hand. Something like connecting the noninverting input to output, inverting to ground, but this might not be right,

 

[Roff]

Here is a lamp fader designed in LM 324.There are many op amp designs used to fade LED's.You may have experienced like this before.In the original circuit the R1 is directly connecting to pin7 (not via SW).

It starting from zero.The brightness is increasing smoothly & after it reaches to maximum brightness again its reducing to zero.

I added a SW near the R1 so when you press SW its changing the brightness level from zero to max & max to zero.

My ques is I need two switches one is to increase brightness other is to decrease.

Can anybody suggest a method for this without taking a microcontroller.

I have attached the Schematic.

Thankx.

I don't understand what you are trying to do with the switch.

 

[Hero999]

Make it fad on/off?

To be honest I'm too lasy to look at the datasheet for the pinout and figure the circuit out.

I hate unclear schematics like this which just show an IC outline and not the opamps or comparators.

 

[Roff]

As drawn, the switch will cause the oscillation to stop when opened, and as long as the switch is open, the LED will sloooowly fade down, eventually going off, due to op amp bias current. Closing the switch will make the oscillation start again.

 

[Gayan Soyza]

Anyway thankx for ur replies.Some are unclear about this schematic but some Smart guys can.I'm also too lazy to draw diagrams with built in functions.Its easy to draw a box than a triangle.normally I'm using the easiest method.

A little more about this diagram.when the SW in the normal position (open) the bulb is lights up (not changing the brightness).when u press & hold the SW its incresing brightness & when it reaches to the max brightness its decreasing the brightness & vise versa.......when u release the SW it lights up in a state.

So I need two switches one is to increase brightness & other is to decrease.
I already made this with a microcontroller but I need to do this with another method.....