humming noise from the LDD-350h when fed by lower voltage source - The Planted Tank Forum
 
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post #1 of 7 (permalink) Old 10-23-2016, 07:34 AM Thread Starter
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humming noise from the LDD-350h when fed by lower voltage source

Hello all,

I planned to supply the meanwell LDD-350H with a 19V pC power adapter. The LDD is to feed a chain of leds having around 51V in forward voltage. Some members have noticed a hum noise when input voltage is lower than the output voltage. Is it systematic ? Is there a simple way to overcome it other than having higher voltage power supply ?
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post #2 of 7 (permalink) Old 10-23-2016, 12:35 PM
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I planned to supply the meanwell LDD-350H with a 19V pC power adapter. The LDD is to feed a chain of leds having around 51V in forward voltage.
Typical LDD input voltage requires about 3 volts overhead.
@ 51VDC required output you would need 54VDC going in.


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post #3 of 7 (permalink) Old 10-25-2016, 01:43 AM
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noise when input voltage is lower than the output voltage.
LDD are buck voltage regulators the above is impossible...

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post #4 of 7 (permalink) Old 10-25-2016, 11:15 PM Thread Starter
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Thanks Jeff. Admittedly it is a buck step down driver, i misread some posts and did not understand the data sheet.

i still want to use my cat VI laptop charger to pump the ldh-45-350. Can it step up the voltage from 19V to 51V ?

Last edited by Darkblade48; 11-06-2016 at 11:00 PM. Reason: Please use the edit function for back to back posts to keep threads cleaner
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post #5 of 7 (permalink) Old 11-06-2016, 02:19 PM
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i still want to use my cat VI laptop charger to pump the ldh-45-350. Can it step up the voltage from 19V to 51V ?
There are tons of boost converters out there..

put number inn eek bay search.

Just remember a boost to 56V (LDD-H input max) means 52V out max at the LDD..

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Last edited by Darkblade48; 11-06-2016 at 02:33 PM. Reason: No eBay auctions
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post #6 of 7 (permalink) Old 11-06-2016, 09:20 PM Thread Starter
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There are tons of boost converters out there..
271833256005

put number inn eek bay search.

Just remember a boost to 56V (LDD-H input max) means 52V out max at the LDD..
Hem...i guess the boost converter your Eb reference links to is adjustable in current by tuning the 2 potentiometers (no instructions for use nor handy datasheet is available) but it seems not to have any pwm dimming input.
The question remains: using the min specified input voltage, can I get the max output voltage ?
It seems that Mean Well is not in the top tier in term of dependability and accuracy but how about those unbranded chinese made boost converters ?
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post #7 of 7 (permalink) Old 11-07-2016, 12:34 AM
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Well my thinking was:
Your power supply++++++++++++Boost converter++++++++++LDD w/ PWM++++++++
The boost converter is both current and voltage adjustable via the pots.. Says so on the board..

Just remember that you have less "amps" available from your power supply after boosting..
Quote:
Output power: effective power P = input voltage V * 10A
@19V you have 190W
@ 56V 3.4A..
If I understand this correctly..

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