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Part 2 of my laser glove question: i have it all hooked up, but am experiencing very low power from the lasers. See more Answered

ok i posted something related to this project earlier but i got it answered and have a new question. im building a laser-glove for halloween, and i for the most part have it all hooked up;
-5 laser pointers in parallel
-9v power source, 0.55Ah
-600ohms resistance/laser pointer
-2 resistors rated at 1.2 & 1.0 kOhm hooked up in parallel to the 9v

my problem: generally all of the laser pointers are very weak. i figured i have a little less resistance than i need as is, so if anything they should be overpowered somewhat?


*NOTE*: regarding safety concerns, i am going to be wearing the glove under a morph suit, which will very strongly damper the power of the lasers, which is why i want them working at full potential 

here is my attempt at the schematic for it. sorry if it is not "correct" but this is how i have it all hooked up more or less:

Discussions

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steveastrouk
steveastrouk

9 years ago

Your lasers aren't current sharing. You should have a resistor per laser.

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kamikaze33
kamikaze33

Answer 9 years ago

of 600ohm/laser?

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steveastrouk
steveastrouk

Answer 9 years ago

You have too much resistance in series. What's the 1.2K//1K for ? Lose it.

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kamikaze33
kamikaze33

Answer 9 years ago

i was told by a buddy in EE to try and get 600ohms resistance. R = 1 / [(1/1200)+(1/1000)] = 545.5ohm
otherwise wont my 9v overpower/burn out the lasers?

what size resistor should i be putting on each laser then?

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steveastrouk
steveastrouk

Answer 9 years ago

What's the laser's ratings ? Current and voltage. You have less than 15mA going through them now.

Steve

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kamikaze33
kamikaze33

Answer 9 years ago

2.12v, 17mA

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steveastrouk
steveastrouk

Answer 9 years ago

That needs ~400 ohms, not 600. Ditch the two parallel resistors.

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kamikaze33
kamikaze33

Answer 9 years ago

ok i tried it with a 390ohm one. still very weak laser beam :(

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steveastrouk
steveastrouk

Answer 9 years ago

Is it any brighter ? Where did you get the current figures for the laser from ? They sound very low to me.

The Ah of the battery aren't as important at the moment as the ability to deliver current.

If you run ONE laser on the battery, is it brighter ?

Steve

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kamikaze33
kamikaze33

Answer 9 years ago

well they are just cheapo dollar store lasers that typically run off 3 button cell batteries. i just used a multimeter on them to get the readings. i only tried it on one laser before. i will hook up the rest of the resistors to the other 4 lasers and see how it all works.

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steveastrouk
steveastrouk

Answer 9 years ago

What battery voltage is that ? 4.5 V ?
Try running it on the battery and check the current.

Steve

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kamikaze33
kamikaze33

Answer 9 years ago

ok so it would appear that it is the quality of the lasers themselves. one laser just read 2.8v, 19.3mA, but it is very weak and i had another laser actually working fine so i am going to post what each laser is reading tomorrow

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kamikaze33
kamikaze33

Answer 9 years ago

if i used a different powerpack, say 4 AA's, would that change it? (im assuming it would because of the Ah, but would that not just affect which resistor i use on the laser modules?

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steveastrouk
steveastrouk

Answer 9 years ago

The Ah are not an issue yet. Have you been using a 9V rectangular battery or what ?

4 AA would need a change in resistor, to 220Ohm.

Steve

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kamikaze33
kamikaze33

Answer 9 years ago

alright thank you ill put a new one on and see what happens