LED string questions...

[chrisatpsu]

Tonight, i bought a 150 count LED C6 light string from WalMart.

the string is 3 wire, except for after every 30th light, there is a 2 wire. (it comes on a spool)

Assuming that, i protect the other end of the wire from being exposed, or shorting out, can I cut this string at the 2 wires, to make 5 30ct strings?

[therealbigjim]

It depends is there is a rectifier ( mabe wrong term) for each section. I know the 120 volt LED strings need them to work. Been looking for led rope light and they take a different the plug then the incan ones do.

[chrisatpsu]

each 30 light section starts with a
2 wire section,
LED
inline cannister
LED
inline cannister
LED
inline cannister
27 more LEDS than repeat

[tbone321]

The canisters are probably the rectifiers and possible current limiters.  A pictue might be helpful but unless someone has already modified that particular string and knows for sure, it will all be just a guess.  Why do you want to seperate them?

[chrisatpsu]

it's a 150 cnt string, i can do more with it broken up into smaller segments, like with an ssr4, or an express.

[Dennis Cherry]

The canisters are probably the rectifiers and possible current limiters.  A picture might be helpful but unless someone has already modified that particular string and knows for sure, it will all be just a guess.  Why do you want to separate them?

If the canister has 1 wire on each end then it is a resistor.

If you have 3 wires on each end or 2 on one end and 3 on the other end then your have part of a diode bridge to make the LED's full wave.

this is a short explanation.

[chrisatpsu]

the first three LED's and the three canisters are in series, with the other two wires just coiled around.

[holland lights]

Yea possibly they just have resistors, i know the cool blue 10.00 strings now 11.47 we use just have resistors on them, the resistors are in the first socket itself. I had to take the led out of the removable socket to fined the resistor.

[tbone321]

The canisters are probably the rectifiers and possible current limiters.  A picture might be helpful but unless someone has already modified that particular string and knows for sure, it will all be just a guess.  Why do you want to separate them?

If the canister has 1 wire on each end then it is a resistor.

If you have 3 wires on each end or 2 on one end and 3 on the other end then your have part of a diode bridge to make the LED's full wave.

this is a short explanation.

It might just be a resistor but it could be a diode protecting the LED's against back voltage as well or a combination of both.  I would agree that if it is single wire in / out then it is a half wave set.

[Dennis Cherry]

You do not need a Diode to protect a series string of diodes. Does not make sense.

If it is a 30 light string it needs a resistor to limit the current of the 30 LED's or they will be destroyed.

I have dissected many designs of Christmas light strings and know the tricks the Chinese design and use.

If you have a 30 LED White string that would be 3.4-3.6V per LED, So total voltage for 30 so 30 * 3.5V is 105 Volts, since we are using 120Vac we need to drop the remaining voltage across some kind of device like a resistor. LED's normal operating current is 20 ma, so we need to drop 15 volts at 20 ma. The theory would calculate to be 750 Ohm resistor at .3 watts, nearest is 1/2 watt. What they will do also is divide the 750 by 2 and put a resistor on each end of the string also, this will allow them to use smaller wattage resistors in the "Canisters"

I hope this clears up some misconceptions about LED strings.

The canisters are probably the rectifiers and possible current limiters.  A picture might be helpful but unless someone has already modified that particular string and knows for sure, it will all be just a guess.  Why do you want to separate them?

If the canister has 1 wire on each end then it is a resistor.

If you have 3 wires on each end or 2 on one end and 3 on the other end then your have part of a diode bridge to make the LED's full wave.

this is a short explanation.

It might just be a resistor but it could be a diode protecting the LED's against back voltage as well or a combination of both.  I would agree that if it is single wire in / out then it is a half wave set.

[tbone321]

LED's are much more sensitive to reverse voltage bias than standard diodes.  Better half wave strings will have a standard diode in the string to protect the LED's from it.  It also makes the string more energy efficient because the added voltage drop across the protection LED reduces the enengy wasted in the current limiting resistor(s).