[Halld-cal] Low voltage power supplies for the LED's

[Fernando J Barbosa]

Hi Christina,

I presume you are referring to the forward voltage across the LEDs not 
the BIAS voltage input, correct? If so, it would be more appropriate, 
considering the monitoring function, to look at the light output 
variation among the LEDs for a given bias setting. I believe that Kappos 
looked at this sometime ago.

Regarding the power supplies, each supply channel has a maximum 5A 
output. It would be useful to have the specifications for current draw 
for the +5V and BIAS supplies per board for the control board and for 
the LED board. The power supply modules that we will use are Wiener 
MPV8008L (8V, 5A, 8 channels) or MPV8016 (15V, 5A, 8 channels) if needed 
for the BIAS. I am using these for all LV in the experiment and they 
work very well.

Best regards,
Fernando



On 11/8/2012 8:49 AM, Christina Kourkoumeli wrote:
>
> Dear Elton,all,
> Further to our discussion of Tuesday I attach a plot produced by 
> Stratos showing the number of flexible strips versus the voltage of 
> the contined 10 LED's .As you we if we supply them by  r 9 supplies, 
> then the output difference  between LED's -under their nominal 
> voltage-is 0.25 Volts.So presumably we will supply them with a median 
> value  of DC voltage in that particular group.
> We have to be careful, though, since we have a large number of strips 
> with values of voltage between 2.75 and 2.5 Volts. This means that one 
> supply would have to supply about 900 LED's.Fernando can tell us if 
> this is feasible currentwiseor we need more than one supply.Also we 
> may need additional ones  since the strips may be located on either 
> sides of the modules.
> In any case, if we decide now on the number of supplies we will ship 
> the strips grouped likewise to Jlab.
> Cheers,
> Christine
>
>
> -
>
>
>
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