Author Topic: Pixelnet strobe controller  (Read 9887 times)

Offline zwiller

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Re: Pixelnet strobe controller
« Reply #30 on: February 03, 2016, 07:42:56 AM »
Well, good guess:  .5A/500ma wall wart...  So, ideally if I am not using any CC or current limiting I would want to mate current of PS to leds?  IE - running a komblinkin with (16) 3w/700ma would require 11.2A @ 5vdc.  16*.7=11.2A.  But then I assume since all are not on when blinking randomly I would then be sending 11.2 to 1 or 2 leds at a time?  In any event, I understand the Dirk method is not a perfect solution but seems rather strange to invest much toward protecting leds that are a dime... 
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Offline pixelpuppy

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Re: Pixelnet strobe controller
« Reply #31 on: February 03, 2016, 08:52:55 AM »
Well, good guess:  .5A/500ma wall wart...  So, ideally if I am not using any CC or current limiting I would want to mate current of PS to leds?  IE - running a komblinkin with (16) 3w/700ma would require 11.2A @ 5vdc.  16*.7=11.2A.  But then I assume since all are not on when blinking randomly I would then be sending 11.2 to 1 or 2 leds at a time?  In any event, I understand the Dirk method is not a perfect solution but seems rather strange to invest much toward protecting leds that are a dime...

If you're going to use a 5v power supply, then why not go with the 2.2ohm, 1watt current limiting resistor?  They are small and cheap and not big like the 5w or 10w you would need with a 12v supply. 
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Offline AussiePhil

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Re: Pixelnet strobe controller
« Reply #32 on: February 03, 2016, 03:39:54 PM »
Well, good guess:  .5A/500ma wall wart...  So, ideally if I am not using any CC or current limiting I would want to mate current of PS to leds?  IE - running a komblinkin with (16) 3w/700ma would require 11.2A @ 5vdc.  16*.7=11.2A.  But then I assume since all are not on when blinking randomly I would then be sending 11.2 to 1 or 2 leds at a time?  In any event, I understand the Dirk method is not a perfect solution but seems rather strange to invest much toward protecting leds that are a dime...

Finally read the komblinkin and dirk cheap posts........ just another design that works by sheer dumb luck, not disputing it can work and that you may even scale it to 3w LEDS but it's neither good design nor shows any real understanding of how LED's actually work.

by the way you don't "send" current to LED's ...... LED's will draw current depending on Vf and series resistance and in practice a LED with no series resistance will draw as much current as available till it burns out if current available exceeds Imax.
LED's are in reality quite tough and can handle quite a bit, though as you go up in power the more "fragile" they become.
 
In the Dirk Cheap strobe setup current gets limited purely by connector and cabling resistance and the LED's are only saved by this and short on times. low duty cycle. This is why it may well scale to 3W and may even do it well due to even higher cabling losses

Offline zwiller

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Re: Pixelnet strobe controller
« Reply #33 on: February 04, 2016, 11:01:50 AM »
Looks like those resistors are readily available and cheap.  Those 3 watters were NOT an easy find...  I am actually a bit excited since I now realize that didn't even power these to their full potential!  ;D  Gonna dig for a 700ma wall wart.   

Offline pixelpuppy

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Re: Pixelnet strobe controller
« Reply #34 on: February 04, 2016, 02:46:19 PM »
Looks like those resistors are readily available and cheap.  Those 3 watters were NOT an easy find...  I am actually a bit excited since I now realize that didn't even power these to their full potential!  ;D  Gonna dig for a 700ma wall wart.
You might consider getting a benchtop adjustable power supply so you can "play" with these things more easily and safely.   If you get one that supports CC then you can play with the current limit and see how the leds perform at different current levels.  They are available in all grades and price ranges including some low end "hobby" grade units for under $75.  That may seem like a lot just to play with leds, but if you have one you will use it for a lot of other things as well.

At a minimum you should get the meter out and measure how much current the LED is drawing from your different wall warts.  The one you have that was rated for 500mA may have been putting out more or less, we really don't know.  They are not regulated, they are just limited by the physical capacity and {lack of}quality of their internal parts. 

If you want to play at the limits, get an assortment of low-ohm resistors.  Play with 2.2ohm (591mA) and then 1.8ohm (722mA) and maybe even 1.5ohm (867mA).

I was going to grab an assortment of these leds in different kelvins so I could do some playing too.  But its the chineese new year right now so mine will have to wait... :-[

Offline zwiller

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Re: Pixelnet strobe controller
« Reply #35 on: February 05, 2016, 08:32:04 AM »
I have thought of getting a bench PS.  Mostly because they look cool and create the appearance that I know what the heck I am doing.  ;D  The reality of it is, it'd be convenient not having to jury rig wall warts and/or other PS up to test stuff and most often I do not have the amperage capacity I need...  Just took a gander and prices have come down.  What do you think of this one?  http://www.amazon.com/Mastech-Single-Output-Power-Supply-HY3003D/dp/B004ISQ270  Also thanks for reminding me my fuses in my DMM need to be replaced. (can't measure current) 

Yeah, the New Year is interrupting me too.  Thank you for the quick reference of the resistors.  That 1.8 ohm looks perfect, just over 700ma.  That said, maybe with the wire/voltage drop (I am estimating 4-8' lines of Cat5) the 1.5 ohm will work. 

Offline pixelpuppy

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Re: Pixelnet strobe controller
« Reply #36 on: February 05, 2016, 09:34:58 AM »
They are extremely useful and I'm confident you won't regret getting one.

I know nothing about that specific model, but for hobby use I'm sure its fine.  For me, I'd feel limited with the 3A max output.  If 3A is enough for you, here's another that is less than $50 http://www.amazon.com/Tekpower-TP1803D-Linear-Digital-Variable/dp/B00EUH18DC/ref=pd_sbs_328_4?ie=UTF8&dpID=41G-2sNZ0vL&dpSrc=sims&preST=_AC_UL160_SR101%2C160_&refRID=11EXRMCV1P4YV15QPPW7

For me, I want at least 5A since that's what a lot of pixel controller outputs are limited to. Here's another one that is a few bucks less than your first model and can handle up to 5A http://www.amazon.com/Tekpower-TP3005E-Adjustable-Switching-Digital/dp/B00PWNQMYI/ref=pd_sbs_328_2?ie=UTF8&dpID=41NmqZGeSHL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=11EXRMCV1P4YV15QPPW7

Disclaimer: I don't have specific knowlege of any of these particular models, these are just sample of what I found with simple browsing on Amazon.

Offline zwiller

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Re: Pixelnet strobe controller
« Reply #37 on: February 05, 2016, 09:50:52 AM »
Doh!  Had an old link in clipboard and posted wrong link.  Definitely want 5A for that exact reason!  http://www.amazon.com/Precision-Variable-Adjustable-Digital-Regulated/dp/B00LBOICL8/ref=sr_1_1?s=industrial&ie=UTF8&qid=1454690582&sr=1-1&keywords=PS-305d  I don't see anything mentioned about CC but I suppose that is a given with these? 

Offline pixelpuppy

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Re: Pixelnet strobe controller
« Reply #38 on: February 05, 2016, 10:04:21 AM »
The picture shows LEDs on the display for CC mode or CV mode.  But that Hi/Lo amps pushbutton seems a bit cheesy and accident-prone.  Some of the reviews are a bit dubious as well.  Several comments relating to high voltage and current spikes when first turned on concerns me.  I think I would spend a few more bucks for the Tekpower or other slightly higher priced unit.  IMHO

Offline zwiller

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Re: Pixelnet strobe controller
« Reply #39 on: February 05, 2016, 10:32:55 AM »
Good eye on the hi/low switch!  That is odd.   :o 

Offline t.jo13

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Re: Pixelnet strobe controller
« Reply #40 on: February 05, 2016, 05:17:45 PM »
Zwiller, check circuit specialists they have several that are reasonable)

Offline zwiller

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Re: Pixelnet strobe controller
« Reply #41 on: February 06, 2016, 07:08:23 AM »
Thanks.  Forgot about them.  That's where I got my soldering station...  Still holding up great for over 5 years now.

What's the difference between the models with just black and red and the ones with the black, red, green (ground) outputs?  These are 2x the cost but specifically mention CC.
http://www.circuitspecialists.com/csi3005sm.html
http://www.circuitspecialists.com/dc-bench-power-supply-csi3005x5.html

Offline pixelpuppy

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Re: Pixelnet strobe controller
« Reply #42 on: February 06, 2016, 07:42:58 AM »
The green is just a direct connection to earth via the the grounded input AC cord.  Its handy if you are working with a static mat but otherwise no big deal.
The more expensive unit has DUAL outputs.  One is variable and the 2nd is a fixed 5v 1a output.  If it were two variable outputs, that might be worth something but since the 2nd output is fixed at 5v 1a, its not worth twice the price IMHO

Offline AussiePhil

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Re: Pixelnet strobe controller
« Reply #43 on: February 06, 2016, 11:13:54 PM »
The green is just a direct connection to earth via the the grounded input AC cord.  Its handy if you are working with a static mat but otherwise no big deal.
Actually reading the manual, the Green is DC Ground, Black is Negative voltage rail and Red is positive voltage and it appears to allow for -30v.

The cheap one allows you to set the current limit value whereas the only does true constant current.......

Offline pixelpuppy

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Re: Pixelnet strobe controller
« Reply #44 on: February 07, 2016, 08:31:32 AM »
Actually reading the manual, the Green is DC Ground, Black is Negative voltage rail and Red is positive voltage and it appears to allow for -30v.
I don't have that specific unit, so you could be right, but where do you see that?  The schematic shows its connected to earth and has capacitors to each rail which will block DC, right?   Specs list only 0-30v, not -30v. 

Other more expensive units with a green GND post may have the capability you describe, but I don't see it in this unit.  I'm not sure we're looking at the same thing here.

Quote
The cheap one allows you to set the current limit value whereas the only does true constant current.......
Again, I don't have that specific unit so you could be right.  But the display has indicators for CV or CC mode which leads me to believe its CC capable...at least well enough for hobby use.   If you can set a current value and it fluctuates the voltage to keep that current level isn't that a constant current supply? What do you mean "the other does true constant current"?

Not arguing, just trying to understand.
« Last Edit: February 07, 2016, 08:41:23 AM by pixelpuppy »

 

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