from what i can tell the same as before.
dim - light - dim - light - etc

i was brave and had it on for a second without the big capasitor in the circuit and the LEDs stayed on while 'blinking' really fast

Edit:
Dc current through the rectification and filtering circuit also has awquard fading...

 

"Before"? Do you mean that the LEDs do the same thing whether or not the motor is connected, or that they operate as expected when the motor is disconnected but not when it's connected?

Yeah. You want that cap in there. When the incoming sine wave is rectified it doesn't make it a nice, even DC voltage; it just takes the sine wave and inverts half of it so it's all on the positive side of 0V. It's still "bouncing" very quickly from 0V up to 12V. The cap smooths that out to a steadier voltage.


Torben

__________________
Curiosity was framed. Ignorance killed the cat.

 

I ment it is still doing the same jeky on/off if the motor is connected or not connected

 

Hm. Try putting a bypass capacitor in there. Maybe 10uF (I'd try anything between 1uF and 100uF) near the op amp, with the positive leg close to the op amp's +Vcc pin and its negative leg to ground.

Does that help settle things down?


Torben

__________________
Curiosity was framed. Ignorance killed the cat.

 

Hi Torben,
The output of the transistor that drives the LEDs does not go anywhere near 12V when the supply is 12V. My number crunching schematic lists the peak voltage at 7.6V. So a single 1.8V LED will have a current of 58mA, not 102mA.
The schematic is designed for two LEDs in series and a 9V supply. So then the current is only 17mA.

__________________
Uncle $crooge

 

Argh. That's what I get for overlooking the very obvious, I suppose. Thanks for pointing that out.


Torben

__________________
Curiosity was framed. Ignorance killed the cat.

 

Im not 100% sure what your saying audioguru, but the LEDs are working at a preferable brightness atm, and adding another pair of LEDs in series, in parellel with the other pair doesnt seem to make the LEDs fade at all... Not sure how it all works, hehe....

Putting a 472 capacitor between pin 8 and ground seems to of done something
Its working now! LEDs are fading on and off, and the motor is moving just fine.
at first the LEDs were still fading oddly, but after awhile they corrected themselves. Now i have taken the transistor out of the circuit and it is still fading correctly.

But what i think will happen is that after turning the power off and leaving it for awhile will result in the awquard fading again... Or maybe the circuit just needs to 'warm up' before working properly because of the AC -> DC stuff?

Ill turn it off, wait a hour and look at it then

i have noticed something else now ( sorry to be a pain! lol)
But the motor is getting pretty darn hot. It was originaly taken from a optic fibre light and would of been set up in series with a lamp. Its specs again are12 AC 11/12 rpm 1/1.5w

 

He's saying that I buggered up the LED voltage calculations. Your resistor should be fine as is.

I'm betting you meant that you took the capacitor out, not the transistor.

Just try it after the LEDs have stopped fading once you've turned it off. Turn it back on without the bypass cap and with the bypass cap.

I'm afraid motors are still a bit outside my field of experience. It could be normal, or it could be about to die a horrible smokey death. I think it's possible that the resistor and cap I put across the motor terminals in the original rectification/filtering schematic are adversely affecting the motor.

What happens if you run the motor straight from the 12VAC adaptor, with the sculpture load attached, but not the rest of the circuit? Does it still get hot?


Torben

__________________
Curiosity was framed. Ignorance killed the cat.

 

You said that the motor is a 12VAC one and you are trying to run it on 12VDC?
A 472 supply bypass capacitor is way too small, it is only 0.0047uF. It should be 47uf which is 10,000 times bigger.

__________________
Uncle $crooge

 

In my original schematic the 12VAC for the motor is drawn from the lines before they go into the bridge. If it's hooked up like I drew it, the motor should be getting 12VAC (assuming that the circuit and motor aren't loading the adaptor enough to drag it below 12VAC).

I forgot to mention exactly what you just said about the bypass cap. I said to try something between 1uF and 100uF, certainly not as low as a 472.


Torben

__________________
Curiosity was framed. Ignorance killed the cat.

 

... yes i ment capacitor.... lol

and the motor is getting 12AC and is a 12AC motor, so that shouldnt be the problem

Ok, i see what is happening now! It starts off pretty odd with the whole, bright -> dim -> bright -> etc with no 'fading' between the 2 states. But gradualy more 'fading' accours and eventualy it does the desired smooth fading.

If i turn it off and back on after awhile, it also fades propely right away. But the longer i leave it off the longer the delay is for it to fade properly, that is probably why i assumed it just wasnt working.

The other 472 capacitor seemed to act as a 'jump start' and disconnecting it from the circuit early on causes the LEDs to fade properly right away.
(cant be sure of that though as the LEDs are working now, lol)


The motor still gets very hot if its directly attached to the adapter with the load on or not.... Thats why i started thinking it could be becuase its not paired with the lamp it was intended to be with as well as the adapter i am using now.

Ive just got the lamp (i kept that too) set up with the motor atm and im going ot leave it on for a bit, see what happens its a 12V 5w lamp

 

Ok i think that was problem.
Without the lamp there i swear i could of cooked a egg on it. I couldnt touch it without it hurting.
With the lamp there it is now hot, but not half as hot as before! Problem is that i dont want that lamp there and i would say it is still a little too hot.... Hehe.

 

What is the current rating on the adaptor?

Do you have a multimeter which can measure AC voltages? If so, it would be good to know what the actual voltage going to the motor is when it's in circuit.

What was the original power supply for the motor? If you dug the motor and lamp out of an existing unit, can you perhaps also dig out the power supply and use that, if it has a higher current rating than the adaptor you're using.

Have you tried a proper bypass cap?


Torben

__________________
Curiosity was framed. Ignorance killed the cat.

 

Is the timing capacitor for the fading a non-polarized one or two polarized caps connected in series back-to-back?

__________________
Uncle $crooge

 

I cant check the adapter yet because im at work again, but ill look when i get home. Im faily sure it said output: 12v 500hz(?) or something like that
No i dont have a voltmeter to my knowlage....

The lamp, motor and adapter all came from a disco ball toy thing. So im guessing the motor would normaly get that hot.... Its just that originaly the motor was suspended in a plastic box and not between two pieces of wood, and id rather not have it damage all my hard work or be a fire hazzard in my bedroom!

Im still using the original capacitor stated in the fading circuit adobe file. I dont have any non-polarized that match the same value or two polarized capacitors to replace it with at the moment.