Need Electronics Advice

[Player0]

If anyone here knows about this stuff :) I really want to start going out with lighting up the cube, fiber optics, blue led effects, etc. Simple stuff that will look cool.

But one thing I want to do is have 3 or 4 cold cathode lamps in my case, of different colors, blue, black, green, and maybe red. But I want to build a controller that would fade each light on and off while the next one comes on.

I thought I could use say three 555 timers, and use these to control the cycle of each lamp, using a transistor to drive the 12v lamps (i imagine they draw too much current to be powered straigt from the 555. I could use a simple capacitor timer to control the fading on and off. But what gets tricky is that each lamp needs a longer off duration than on. And im not sure how to manage that.

Anyone have any thoughts?

[dicki]

hummm... fading florescent lights is a real pain... you need special controllers for that... also do you think a transistor will switch enough current to switch it on? i'm thinking power transistors at the very least... more likly relays and then you loose the option of control

i gotta say i'm not great at electronics but those are the first thoughts that go through my head

dicki

[billg2911]

check this out it looks a lot better then going through all that

http://www.cksauce.com/products/lightwasher.htm#

[tripodal]

ive commonly seen 120watt transistors available at radio shack.. primarly assigned to music reproduction, would one of thos or some scavenged out of an old reciever be acceptable as they are used to dealing with more current than the average resistor
also it would seem more logical to use some from an old burnt out car amp, putting out 100watts on a 4ohm load is lots of current
just my thoughts

[Player0]

Well im not going for a full fade out. I can fade the cold cathode out simply by limiting the current. As long as a fast fade, i dont need anything special. I just want the color change to sort of blend, rather than be an abrupt switch.

Im not worried about transistors. The power drawn by the cold cathode is extremely minimal. High voltage low current.

Its still the timing issue :)

[tripodal]

ahh, i think i misunderstood your first post. my bad.

so you are saying that it takes longer to power on the light, than to power it off?



or are you trying to figure out how to run them at 25% duty cycle?

perhaps you can run a capicitor/resistor combination that when charged keeps the timer off... and when charged enables the timer, turing on the light,would probably take some trial and error tho.

or you could control the following light with the previous lights timer... running like dominoes, only starting when the one before is dimming.

again im not too sure about electronics, sounds like you most likely know more than i, but i offer another perspective

[GITster]

well, if you can get the power electronics side of things working, use a PIC :)

[KMS]

Player0 if you get the data sheet for the 555 (see http://rswww.com) it will provide all the timimng data you need, the 555's are a little limited though, if you want me to draft you a circuit let me know and i'll sketch scan and post :)

[Player0]

Go ahead id be very interested in seeing your circuit :)

I suppose I'd have to use 556 chips to get asynchronous clock signals, and combine the pulses with an OP amp. That would allow my lamps to be off 2/3 of the time and on 1/3 of the time.

I just wonder if using a clock divider would be better...its less chips. Use a single 555 to time it all, and then use a decade counter to split those signals in to how ever many lamps i want, and then use the transistor drivers to power the lamps (or relays, since I may want to isolate the high-voltage generator circuit from my timer circuits). As for fade, Ill just use a large capacitor and a pot to adjust the fade timing manually of the ends of the relays.

[Player0]

The only problem with the decade counter is that two lamps can't be on at the same time, which is necessary for a smooth color transition. I could use *extremely* large capacitors to keep the lamp active for another half a second after the divider switches...but, im not sure thats the best way.

[dicki]

i like gitsters idea of a pic, firstly you'll be able to control the timings exactly and even randomise them and do other funky effects, and secondly you can control the pic through the serial port or an internal usb port of your computer and manually take control or alter the timings

i'll definatly be including a pic in my next pooter because i want to use it to moniter and control my temperatures and fans, lighting is just a little extra thing you could do

dicki

[Player0]

Well...one of those little PIC modules would work great. I think radioshack sells the little BasicStamp ones for $35, and you need the carrier board for another $15. That $50 is a bit more than I wanted to spend...

If I did it with a bunch of timers, I could shave the cost down to under $10 easily. Not saying its a bad idea, I could do programable light shows, make a fan controller out of it, etc. It would be neat...but, Im not sure I want to spend $50 to do it :)

[4.6POWER]

I just wanted to say I think this is one of the coolest ideas for a case-mod that I've ever heard. I'm not gonna pioneer the way like you guys... but if this works out, I'm gonna be nagging u guys for directions ;)

[Player0]

Also thinking of hooking the light fader to the lineout on the sblive. I found an easy schematic and I can have the lights flow with the music.

Mebbe :) Its gonna take alot of tweaking though. I need to take a trip to 'the shack'.