Boost converter LTC3401

[audioguru]

Compact fluorescent light bulbs have a 40kHz oscillator inside. The oscillator is made with many good electronic parts.
There are websites that show the schematics of many models.
Here is the schematic for a compact fluorescent light bulb:

 

[Sceadwian]

How accessible are these components though? I'd imagine they're at least mostly potted circuits? I've never tried to take a CFL apart before, but if the innards are actually usable I might buy a couple just to examine the internals.

 

[bananasiong]

OMG, ferrite coil from farnell is not cheap! Not sure it takes how long to ship here, haven't ordered from them before.
I'm still looking for the fluorescent light bulb from my friends.

 

[bananasiong]

I'm going to buy from farnell, the electronics shop has the catalog, so I can order from them.
Multilayer ceramic capacitor, I think this is what I need which is ceramic cap, but what is multilayer?
**broken link removed**
**broken link removed**
And the ferrite coil I've found is Ferrite Drum Core, is it suitable?
**broken link removed**

I wanted to order the parts earlier, but I just got my salary this few days, and I can't order for only 1 unit for some of the products.

 

[Garibaldi]

DO NOT break the bulb of a CFL - they contain mercury! You can sometimes carefully wiggle the bulb enough to break the wires at the base and remove the bulb for safe disposal (preferably recycling). You can then pull the base apart to get to the electronics - and replace them with a driver for a proper LED bulb...

 

[Sceadwian]

Oh just break it, but don't breath it! =) and make sure it's outdoors so what little is in there dissipates away from people/critters. You risk being close to it when it breaks by trying to break the base carefully. The real threat from CFL's and regular mercury lamps in the first place is the mass disposal of them. I work at a small company who disposes of full sized tubes legally by putting them in the dumpster and smashing them. We're a 'small quantity generator' and not regulated under the same laws as larger companies. It's illlegal for larger companies that dispose of multiple order of magnitudes more bulbs to do this though. A single large company doing this is equivilent to hundreds if not thousands of smaller companies and people. Destroying a single CFL for hobbyist is safe unless you do something stupid like crack the tube and try to snort the gas.

 

[Hero999]

I've smashed numerous fluorescent tubes and I've never seen a single drop of mercury leak out from them! I would estimate that even a large fluorescent tube probably only contains a couple of mg of mercury so I wouldn't worry about it,

Broken glass is probably the worst hazard and the phosphor probably isn't too good for you either. You don't always need to break the tube to get at the electronics, just saw round the base and they should fall out.

 

[Garibaldi]

A large 4' tube contains about 10-12mg for low concentration versions (down from about 50 in the 80's) and a standard Edison socket version about 5mg - which is more than a year's safe exposure. You don’t see it because in the vacuum of the tube, it exists as a gas. Now, you're not going to absorb all of that immediately with a cold bulb, and most will dissipate with ventilation in warm air temperatures. Where it will just be spread over a larger area and persist, or become the even more toxic methyl-mercury, until absorbed by somebody else. It also bioaccumulates in your body, so I would strongly suggest against a cavalier attitude about even small exposures. Some wise counties in the US have outlawed disposing of them in the garbage.
Sceadwain, if you keep smashing those tubes for another 20 years, you will indeed become mad as a hatter. Hopefully for your sake and everybody else's, LEDs will have replaced the Death Tubes long before then.
But I digress, if you do SAFELY (sawing around the base is probably the best option) open the base of the bulb, you may be able to recover usable components, but with the few I’ve opened, most of the components were burned or corroded and unusable.

 

[justDIY]

I'm going to buy from farnell, the electronics shop has the catalog, so I can order from them.
Multilayer ceramic capacitor, I think this is what I need which is ceramic cap, but what is multilayer?

multilayer is good - just means they've sandwiched multiple capacitance layers together to achieve that rating. you might want to consider tantalum capacitors, they are very common in smps circuits, the datasheet should recommend brands and model numbers known to work.

And the ferrite coil I've found is Ferrite Drum Core, is it suitable?

that still looks like an RF choke ... try searching for power inductor. at only 10uh, even a small power inductor will have a rating of several amps. Here's something good from Farnell's sister company Newark. Your datasheet will recommend what inductors to use, or at least what supplier and series to look at.

https://www.newark.com/jsp/Passives...NICS/CD1-100-R/displayProduct.jsp?sku=27K6797

another, perhaps smaller in size

https://www.newark.com/jsp/Passives.../PM105-100M-RC/displayProduct.jsp?sku=63K3495

 

[bananasiong]

that still looks like an RF choke ... try searching for power inductor. at only 10uh, even a small power inductor will have a rating of several amps. Here's something good from Farnell's sister company Newark. Your datasheet will recommend what inductors to use, or at least what supplier and series to look at.

https://www.newark.com/jsp/Passives...NICS/CD1-100-R/displayProduct.jsp?sku=27K6797

another, perhaps smaller in size

https://www.newark.com/jsp/Passives.../PM105-100M-RC/displayProduct.jsp?sku=63K3495

OMG, I thought as long as they are ferrite inductor it will be working fine. I've ordered that After comparing the ferrite inductor with your recommendations, I found that the resistance of the inductor that I've order is more than 10 times compared to yours.
Those companies recommended from the datasheet don't supply to farnell, except Murata, but they have neither power inductor nor ferrite inductor for that value. So I tried searching on other company and I found this:
**broken link removed**
This is the only 10 uH power inductor in farnell site.
Or this? It has low resistance.
**broken link removed**

The product search in farnell's site is really messy, the inductor type is categorized as:
..
High current
Inductance
Inductor
Line reactor
..

Why these inductors don't even have value:
**broken link removed**

 

[justDIY]

How very strange, it seems the only kind of inductor they carry is a choke (consider the DC amps rating in addition to resistance).

oh, here, I think I found something you could use, although at 14A, it's a bit more powerful than you need and its kind of expensive!

**broken link removed**

this one is more affordable and suitably rated, but it's less inductance than you specify:

**broken link removed**

My recommendation at this point, pick another vendor, or call up your local Farnell office and ask 'em why they don't carry a 10uH inductor rated for approximately 4a.

 

[bananasiong]

Hi,
Thanks for your response. The first one you found is really expensive, and the second one is no longer stocked by farnell.
I've found from RS site, this inductor is rated 5.5 A.
http://www.rsmalaysia.com/cgi-bin/b...ljkkdhmfcefeceeldgkidhgn.0&cacheID=mynetscape

 

[justDIY]

that one looks like a winner!

one thing to note about ferrite smt inductors, if you're soldering by hand, the ferrite gets really fragile when it's hot - I've busted a couple bobbin type smt inductors to learn that

 

[bananasiong]

that one looks like a winner!

What to do, this is my country.. everything is really difficult to find.. sigh
But I'm not sure whether I can order the parts of RS from the electronics shop which I order farnell parts, need to check them out tomorrow.

one thing to note about ferrite smt inductors, if you're soldering by hand, the ferrite gets really fragile when it's hot - I've busted a couple bobbin type smt inductors to learn that

I haven't tried soldering smt components before, only some ICs. Take this chance to try it

Thanks

 

[bananasiong]

I just got some 2.9 A inductor from Bourns, SDR1005-100ML, this is cheaper.
https://www.electro-tech-online.com/custompdfs/2007/09/PM3316_Series_Update.pdf
Just tested, it works for only 1 minute on the LCD display with a single AA cell, measured 1.1 V.
Or shall I use the higher current rating (5.5 A) inductor as suggested in the previous post?
https://www.tdk.co.jp/tefe02/e531_slf12575.pdf
I've got ceramic caps for the input and output as recommended in the datasheet already, leave only the inductor now.

 

[aussiepoof]

What to do, this is my country.. everything is really difficult to find.. sigh
But I'm not sure whether I can order the parts of RS from the electronics shop which I order farnell parts, need to check them out tomorrow.

I haven't tried soldering smt components before, only some ICs. Take this chance to try it

Thanks

Banana: Farnell and RS are as expensive as all hell no matter what country you're in!! I avoid the Australian arms of these companies for that reason too. Try these two:

**broken link removed**

or

http://www.altronics.com.au

Both will post parts to you rather than forcing you to use Fedex/UPS etc., and their prices are very reasonable. Altronics has the inductors you need and is based in Perth, Futurlec is cheaper on other components and though also based in Australia they ship from Thailand. I dare say both will prove cheaper even when you include the postage to Malaysia!

Regards,
Paul

 

[bananasiong]

Banana: Farnell and RS are as expensive as all hell no matter what country you're in!! I avoid the Australian arms of these companies for that reason too. Try these two:

**broken link removed**

or

http://www.altronics.com.au

Both will post parts to you rather than forcing you to use Fedex/UPS etc., and their prices are very reasonable. Altronics has the inductors you need and is based in Perth, Futurlec is cheaper on other components and though also based in Australia they ship from Thailand. I dare say both will prove cheaper even when you include the postage to Malaysia!

Regards,
Paul

Hi,
Thanks for your suggestion
But I do not have a credit card to open any account to purchase from the net. I order from farnell and rs through an electronics shop.