I don't undestand how this circuit works

[beerbaron]

Hi, I have got a solar lamp in my hands. Basically it's a photo-voltaic cell, with 1xNiCd 1.2V battery and a 3.3 white LED.

The circuit is some sort of controller that will on/off with light exposition to the CDS. It will also boost the 1.2V input Voltage to around 3.1 V. It seem to use some kind of switching into the Inductor, and the inductor maintains a steady current.

See illustration @

http://pages.infinit.net/f199/Circuit.JPG

But what I don't understand is that the manufacturer changed the inductor two 2x1 ohm in parrallel...and it still ligds a 3.3V LED How the Charge/Pump be possible without any inductor?

Here is the chip datasheet for who is interested.

http://pages.infinit.net/f199/6601D_english.pdf

Best regards
BeerBaron

 

[itsmoked]

I'm confused as every schematic shows an inductor? But you are asking how it works without an inductor.?

I don't understand

two 2x1 ohm

???

You can increase voltage without inductors by charging capacitors in parallel and then hooking them up in series but usually this is constrained to less than 50mA.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[beerbaron]

Exactly every schematics show an inductor but the circuit I have in hands has none... they seem to have replace the inductor with 2x1 ohm in parrallel depite of what the schematic says. And... it works. I'm confused as well...

BeerBaron

 

[itsmoked]

WHAT IS A 2x1 ohm!?????????????????????
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???!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[btrueblood]

Hmm, are you saying there are two each 1-ohm resistors in parallel, in place of an inductor?

Are the resistors perhaps wire-wound, and have the right inductance to make the circuit work (but maybe are cheaper than purpose-built inductors).

 

[Comcokid]

Could it be that the solar cell on the one you have is several series connected cells providing a higher voltage, and so to use the chip to continue to perform the on/off functions they just eliminated the voltage boost by substituting resistors for the inductor?

 

[VEBill]

In addition to all the other good points...

Are you sure that they are resistors? Maybe they really are inductors that just happen to look like resistors to your eyes.

Do they have colour codes? If so, then maybe the colour code isn't a resistance value but is an inductance value or part number.

You could try measuring the resistance (carefully) and seeing if it matches the colour code - exactly. I'd keep the assumption that they're resistors only if the values matched within tolerance.

PS: It's a wee bit tricky to measure 1 ohms accurately; need a good meter and some understanding.

 

[IRstuff]

A 1 ohm "resistor" might well just be an inductor.

TTFN

Eng-Tips Policies FAQ731-376

 

[TurboXS]

Are they something like this;

http://au.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=608543

http://au.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=516570

http://au.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=106227

Are they in parallel?

Perhaps 2 x 100uH?

 

[beerbaron]

Yeah, they look like TurboXs showed me, they have Yello Brown Black Silver as color code. Which proves us that they are not really 1 ohm resistors. So these must be inductors, never saw or heard of these type before. They look very inexpensive!

Frederic Boucher

 

[automatic2]

Your 'resistors' likely are inductors, and are quite common.