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ArcticMyst Security by Avery

Will VDC affect my drivers output?

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Dec 16, 2009
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The capacitors I bought for my driver are .1uf and 1uf, both with a 50VDC. Is this too much?

Also, I hope the resistors I bought will work, they are 1/4 watt, and 5%

I am building a LM317 driver, with 3 capacitors and a 1k resistor in parallel. There is also one 12 ohm resistor in series after the LM317.
I hope that makes sense, it is supposed to put out ~100ma.
 





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This should be good. The LM317 will take care of regulating and dissipating surplus energy, so the resistors should be fine. About the caps, the 50VDC rating just means they are made to be able to handle voltages of 50VDC, so your build should be fine.
 

Benm

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Yup, its the maximum voltage they can handle. As long as the rating is higher than the voltage in your circuit, you're fine.
 

3zuli

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The capacitors I bought for my driver are .1uf and 1uf, both with a 50VDC. Is this too much?

Also, I hope the resistors I bought will work, they are 1/4 watt, and 5%

I am building a LM317 driver, with 3 capacitors and a 1k resistor in parallel. There is also one 12 ohm resistor in series after the LM317.
I hope that makes sense, it is supposed to put out ~100ma.

1/4W for the current regulating resistor @100mA is a bit weak. at 100mA it should work, but if you later decide to increase the current, make sure you buy at least 0.6W (or 1W) resistor
how is the 1K resistor connected?
 
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Can someone answer his question the other way? Will changing the driver input, affect the driver output (LD) and/or damage him?
 

3zuli

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LM317 is up to 35V, so with enough heatsinking it will be fine
 
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Lets say.. Using the same config.. anything between 12~35v, heatsinked with 1kg copper, will work fine? Lets say, same diode brightness at 12v and at 35v?
 
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^Yes. The regulator will dissipate a little over ½W at 12V and about 3W at 35V though. Running a 445 diode at 1A from a 7V source will also dissipate 3W by comparison.

1/4W for the current regulating resistor @100mA is a bit weak. at 100mA it should work, but if you later decide to increase the current, make sure you buy at least 0.6W (or 1W) resistor

The power of the current sense resistor should be > Vref²/R. 1.25²/12 is 130mW. ¼W resistor can handle 250mW. ¼W resistor will be fine up until 200mA driver output.
 
Last edited:
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This should be a little more clear than my poor verbal description. I used a 10 ohm resistor in this picture, however, but same idea.

picture3kf.png
 




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