how to drive 18v Black&Decker light?

divxdude

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wquiles

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Re: how to drive 18v Black&Decker?

This is how I did mine. Note in here that there is some good discussion as to what drivers to use. You might want to look at the nFlex driver.

Will
 

divxdude

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Re: how to drive 18v Black&Decker?

really want a TI product..is there specs on the flex i can use to compare?
 

divxdude

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Re: how to drive 18v Black&Decker?

they have lots of dc-dc and PWM stuff.. i'm sure those chips can improve performance alot over resistors and samples are rather inexpensive.

i know only enough about these devices to wish i know how to utilize them so could someone help me pick one and and maybe guide me thru the hookups.

want to add 40-50% runtime..

I ordered this one but did not plan for package type and this tiny chip will need a socket no doubt.
http://focus.ti.com/docs/prod/folders/print/tps61059.html

can someone help me find a couple sockets for this type package?
radio shack?

http://focus.ti.com/lit/ml/mpds117d/mpds117d.pdf
 
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Builder

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Re: how to drive 18v Black&Decker?

divxdude said:
they have lots of dc-dc and PWM stuff.. i'm sure those chips can improve performance alot over resistors and samples are rather inexpensive.

i know only enough about these devices to wish i know how to utilize them so could someone help me pick one and and maybe guide me thru the hookups.

want to add 40-50% runtime..
Buck/boost regulators will extend the full output time for your light, but will not extend total runtime at all.

As the voltage drops, the regulators compensate by drawing more current from the battery, cutting into its reserves even more. This also affects the efficiency by which it converts energy as well.

Also, unless low-voltage protected (in the circuit or in the cells), the circuit may permanently damage rechargeables.

Conversely, white LEDs running off LiIon cells with a small resistor will get dimmer as the battery drains, but will shut itself off before the battery is damaged.
 

legtu

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Re: how to drive 18v Black&Decker?

Hmmm... what type of LEDs(5mm? Luxeons?) and at what current levels?
 

legtu

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Re: how to drive 18v Black&Decker?

divxdude said:
I ordered this one but did not plan for package type and this tiny chip will need a socket no doubt.
http://focus.ti.com/docs/prod/folders/print/tps61059.html

can someone help me find a couple sockets for this type package?
radio shack?

http://focus.ti.com/lit/ml/mpds117d/mpds117d.pdf

Eeeeks... AFAIK, there's no IC socket available with that type of IC of package. There are PCB 'converters' that you can solder these type of IC's into but you need to have really fine soldering skills(remember, the IC is only 3mmx3mm, 5 terminals on each side with no protuding legs ;)).
 

Builder

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You have spec'd 20mA LEDs. With 18volts, and based on the capacity of my Makita Power Pak, you can drive 5 of your LEDs in series thru a 220ohm resistor for a run time of over 200 hours continuously! How much MORE do you want?

Unless you are comfortable with assembling from components, and have the right tools to do it with, it's not going to be easy.

You already found out how challenging some of the surface mount components can be - and you haven't touched the fly-back coils/transformers, the capacitors and resistors for starters.

Perhaps to get your feet wet, you can get the TL317 regulator from TI (they license it from NatSemi) and use it as a current regulator:
TL317.jpg

Each "chain" is 5 LEDs conected + to - (Long lead to short lead, the long being +) Change the resistor for 1 chain = 51ohm; 3=18ohm etc. Make the chain 4 LEDs long if you want maximum brightness longer, but a shorter tun-time.

Also, you'll find the LEDs very floody, and they do not work well with reflectors. Get the 10mm 130cd ones here instead, for a tighter spot.
 

divxdude

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yes the LEDs are
http://cgi.ebay.com/White-LED-Set-of-50-XtraBright-5mm-40000mcd-Free-Ship_W0QQitemZ7598153256QQcategoryZ66952QQtcZphotoQQcmdZViewItem

Builder: thanks for that.. i i think i can get a LM317 close to home for 2 bux.

tell me what decides the current level i run my LEDs at? same resistor math as without the regulator? it remembers the R1 current level at start? and either supplement it if low or momentary grounding it if high at a fast pace?
how do chips work...amazes and confuses me..

draws some milliamps and dispenses less in form of light and the rest is converted to extra volts or something?
 
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divxdude

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is the R1 setting a total current of 52ma ? (1.25/24)
which is 26 ma to each chain?
 
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