Thats great! As long as i have a Schem. with the right values and components, ill be fine working from that to make a circuit

Im not so sure about that non polarised capasitor though...
The closest i could find to it was this...

ebay 1u 16v un polarised capasitor

 

Torben suggested a .1 uf capacitor, not a 1 uf.
Something like so.
http://search.digikey.com/scripts/Dk...=478-2430-2-ND


Or if Ebay is your choice.
http://search.ebay.com/1uf-capacitor...ufQ20capacitor

 

Yeah, I did, but only because that's a value I saw used in a similar application. I'm still chewing through a PDF on snubber design--but right now I'm working on fixing Grandma's pressure washer, so the snubber might have to wait until tonight.

Here's the link to the RC snubber design doc I'm reading through: http://www.descartes.com.tw/des/cde/...E-APPGUIDE.pdf
in case anyone is interested.


Torben

__________________
Curiosity was framed. Ignorance killed the cat.

 

Doh!
Just figured out the capacitor values... 4700nF isnt the same as a 4700µF....Went and bought the wrong ones, lol.
I understand it now but the larger value capacitors all seem to be electrolytic and have a required voltage. What voltage capacitors do i need or do i just need to get ones under 12v?

gettin there slowly hehe
Thanks for the help guys would never of got this far with the circuit without your help

 

For a circuit designed for 12V operation, your lowest available (that I know of) option is 16V, and that's pushing it. I'd go for at least a 25V-rated part to make sure you've got the headroom to not exceed the cap's rating even in a worst-case scenario. The 4700uF cap will be a polarized electrolytic, so make darn sure you hook its negative lead to ground and not the other way around--otherwise it could pop and get hot stinky goop all over the place.

The 0.1uF cap on the RC snubber across the motor leads, on the other hand, doesn't care which way it is hooked up, since it *must* be non-polarized: it's operating on AC, so its positive and negative side will be swapped at 50Hz.


Torben

__________________
Curiosity was framed. Ignorance killed the cat.

 

Ok, got all the components now That 4700µF is a scary looking one
Now all i need is to wait for my breadboard to come in the post so i can try the circuit out lookin forward to seeing if i will get it right! lol.

 

Just set up the 'fading' circuit with a 9v battery and it worked great!
But will all the components be safe with a 12v supply going through it? I know the LEDs i bought are 9-12v so im fairly sure they will be fine.

Also, the 'fading' is a little fast, i read in the adobe file that it is the resistor between pins 3 and 6 to ground that i should change to adjust it. But do i need a stronger or weaker resistor to make it go slower?

 

Howdy again! Actually, what it says is that changing that resistor will affect how dim the LEDs get before they go out. Is that what you mean? If you just want to adjust the rate at which they fade up and down, adjust the value of the 47k resistor between pins 2 and 7. Make it higher for slower and lower for faster. Even better, stick a 100k or so linear potentiometer in there with one leg to pin 2 and the wiper to pin 7.

All the components in the circuit will be fine with 12V, but remember that a 12V wall wart will give a no-load reading voltage of well over 12V. I mean, if you just plug the wall wart into the socket and measure its output when it's not powering anything, you'll get a reading of maybe 14 or 15V instead of 12V. The idea is that since they are unregulated, they "sag" the voltage when something draws a certain load through them. Say the adaptor is rated 12V @ 500mA--that means that it's expected to put out around 12V when some device is drawing 500mA through it. If the device pulls less, then the voltage will be higher.

Sounds weird, but it's true.

The point behind all this rambling is that the 12VAC adaptor is going to give you more than 12VDC after rectification and filtering already, and if the adaptor has a high amp rating, you could wind up with more than 15V going into your circuit. I don't think you will exceed the 1458's max supply voltage or max input voltages, although I haven't really crunched all the numbers.

What I'm saying is: I *think* you should be fine, but if it were me, I'd just try it (after making sure I had anyother 1458 on hand in case I was wrong).

Again, I hope somebody will correct me if I'm leading you down the garden path here.


Good luck!

Torben

__________________
Curiosity was framed. Ignorance killed the cat.

 

Ok, i think i have run into my first problem...
I wanted to see what would happen if i was to give it 12v dc to 'simulate' what it would roughly be gettin after the rectification and filtering ( i know u said it will be more, but thats why i say roughly )
So i attatched it to a 12v dc adapter and the LEDs dont faid at all and stay on... But they still work fine with a 9v battery

 

So the LEDs are staying on at a constant brightness all the time? Sorry, when I simmed it I didn't have a model of the 1458 to try so I've simmed using a TL072 model instead. I might have a 1458 out in the workshop though--I may have to put one of these things together this afternoon to see what I can come up with and to get an idea of what it's doing in real life. I don't suppose you have a TL072 lying around to try instead of the 1458, hey?

The easy answer would be: use a 9VAC wall wart. I'm gathering that you don't have one, however. Anyway, I'll see what I can come up with later today. Sorry about the waiting. Have a wife, kid, and job to take care of first.


Torben

__________________
Curiosity was framed. Ignorance killed the cat.

 

You forgot to tell us the forward voltage and how many LEDs you have.

I crunched the numbers for two 1.8V red LEDs in series or one 3.6V white or blue LED.
I show the peak voltages.
1) With a 9.0V supply, the LEDs turn off completely and turn on with a peak current of 17mA.
2) With a 12.0V supply, the LEDs get very dim then turn on with a peak current of 40mA which might burn them out.

The 22uF capacitor must be non-polarized. It can be two 47uF polarized capacitors back-to-back. Maybe that causes your problem with the LEDs not turning off with a 12V supply.

Attached Images

fading LEDs3.PNG (57.4 KB, 11 views)

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Uncle $crooge

 

Ah, this is very true... Sorry

I wanted to try out different things so i bought...
4 X '5mm LED super bright 1000mcd - red'
2 X '10mm LED ultra bright 1600mcd - red'

Thats all the details i have been given... I thought it said 12v also, but i was wrong about that

Shop link

And dont worry Torben, i totaly understand. Im really happy that your actualy willing to put time into trying to help me out

 

Dang, yeah. I forgot to mention that when going to 12V you should change the 100Ω current-limiting resistor on the LEDs to at least a 330Ω to protect the LEDs.

If you don't have a 330Ω resistor you can put 3 100Ω resistors in series.


Torben

Edit: That'll just protect the LEDs though--I don't think it'll help with the always-on thing, unless it brings the LED current low enough to make the dimming visible.

__________________
Curiosity was framed. Ignorance killed the cat.

 

Your "no-name" red LEDs don't have a datasheet. I will guess that their forward voltage is 1.8V.
I will also guess that you have two in series like in the schematic.

__________________
Uncle $crooge

 

Hmmmm.... I can always buy more components if i need to?
Would that other TL072 chip be able to fix this issue? Since ill be buying a few more resistors from there i would like to save on postage

and what voltage LEDs would be desirable? Although the ones i have didnt frazzle out when they where on the 12v... I could also email the website i got them from to see if they can tell me what there voltage is?