Really simple project...help for a beginner?

[dec_lan]

Hey everyone, I think I know how to do this project. However, it involves AC from the wall, which I'm nervous about using. My previous projects have all been powered by 9V batteries, which don't pose much of a threat of burning down a dorm.

I came across one of these being thrown away (wasteful rich college kids):

**broken link removed**

I want to make it so I can put different color bulbs in each..."head" of the lamp, and then an accompanying circuit that would slowly (about .5Hz) cycle through the lamps.

I think I have the basic idea, which I've drawn here:

**broken link removed**

And of course the decimal counter has to have its own power, possibly from a small 5v transformer also feeding off the AC?

A few worries I have: Would this be a good place to put a fuse, just in case? I'd prefer not burning down my dorm. Also, there exist relays that can handle AC, right? And, would any part of this not like the (fairly frequent) switching? Would any parts overheat?

Any other general advice?

Though I don't plan to, I think it should be safe to leave on for days.

Thanks everyone!!

 

[dec_lan]

A couple changes I think. I decided that bulbs probably wouldn't be able to last long under the frequent switching, so I've decided I'll use superbright LED's, about 5 of each color instead of each bulb. This way, I won't have to worry about running massive amounts of current.

Anyone have any good advice?

 

[BrownOut]

You probably don't need a fuse, just make sure the metal frame of the lamp is connected to mains ground. If you do decide to fuse, just use 1 fuse for the wire that brings in mains to your lamp. Caluculate what maximum current you'll need and size the fuse to that current, plus a little extra, say 10 -15% for 'headroom'

 

[dec_lan]

You probably don't need a fuse, just make sure the metal frame of the lamp is connected to mains ground. If you do decide to fuse, just use 1 fuse for the wire that brings in mains to your lamp. Caluculate what maximum current you'll need and size the fuse to that current, plus a little extra, say 10 -15% for 'headroom'

Thanks, but I actually think I've decided to replace each bulb with 5 LEDs of the same color. But overall, the design will be the same.

With LED's, should I wire them in parallel or in series?

 

[BrownOut]

Thanks, but I actually think I've decided to replace each bulb with 5 LEDs of the same color. But overall, the design will be the same.

With LED's, should I wire them in parallel or in series?

LED's don't really make a difference for fusing or wiring requirements. Wire them in parallel, each with it's own current limiting resistor.

 

[Boncuk]

Hi dec_Ian,

how about that idea?

You stay at low voltage (but probably high amperage) using CREE XR-E LEDs for your project. They are available in different colours at 1,000mA max forward current.

You might want to mix colours which you can do by using PWM for each individual LED.

The sockets inside the lamp are easily to be modified for power LEDs.

Boncuk

 

[trennonix]

Try using something solidstate instead of relays, i think the ticking sound would become annoying.
If you're using LEDs than you're going to use DC so why not switch with transistors, or if you're going to stick with AC and use bulbs, you can use Triacs.

 

[dec_lan]

Hi dec_Ian,

how about that idea?

You stay at low voltage (but probably high amperage) using CREE XR-E LEDs for your project. They are available in different colours at 1,000mA max forward current.

You might want to mix colours which you can do by using PWM for each individual LED.

The sockets inside the lamp are easily to be modified for power LEDs.

Boncuk

I'm sorry, I don't really know what you're suggesting...could you clarify a bit?

Try using something solidstate instead of relays, i think the ticking sound would become annoying.
If you're using LEDs than you're going to use DC so why not switch with transistors, or if you're going to stick with AC and use bulbs, you can use Triacs.

Ahh very good point! Are solid state relays more expensive? I thought about using transistors, but doesn't that mean I have to keep them biased then?

 

[trennonix]

The truth is that i don't know much about solidstate relays since i've never used them before and i don't even know what "biased" mean.
but i don't think that a transistor circuit would be complicated.

 

[kinarfi]

stay with 110 volts

a picture is worth a thousand words, this crap drawing is probably only 250 words, but you get the idea and you can control it with low voltage dc