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LED Pars


BlueShift

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hi! a question about 36/1w luxeon leds Moving Heads, anyone saw some units in action? is near a 250w wash unit?

 

Just for Luis> Solo en los colores oscuros. En el color blanco gana por lejos las lámparas de descarga, pero en los colores saturados son mejores los leds, tambien en el flasheo.

 

Regards.

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hi! a question about 36/1w luxeon leds Moving Heads, anyone saw some units in action? is near a 250w wash unit?

LEDs are about 20% efficient, incandescent lamps about 10% so

36 * 1W LEDs * 20% produce about "7.2W of light"

the 250W incandescent * 10% produces about "25W of light"

so for White light the answer is no.

However for a saturated colour (say Green) the LEDs are

12 (Green only, no Red or Blue) * 1W @ 20% = "2.4W of light"

The "25W of light" from the incandescent has to go through a gel. If we use a fairly saturated green (say Roscoe #91, primary green) this has a transmission of only 7% so

25W * 7% = 1.75W of light

so the LEDs would appear brighter.

 

Basically if you want white, LEDs aren't so good. If you want Saturated colours then they really start to come into their element.

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  • 2 weeks later...
I see Thomann have the par 56's in for £47 quid each now!

 

Order code 193247

 

It seems that Thomann now do several variants on the cheapo LED Par56..

 

The descriptions on the web page are confusing - the 47 and 53 pound variants have identical specs, apart from one says 5 DMX channels and one says 4. Both say "showtec" in the description, although one is advertised as "stairville".

 

An email to Thomann didn't clarify very much - in fact it confused matters even more:

There are 3 different types of LED PAR´s at the moment.

It´s Showtec, Eurolite and Stairville. The Stairville LED PAR´s has 5 DMX Channels.

On the other PAR´s it´s different, one charge has 5 the next 4...

I'm guessing "charge" means "type" or "batch"???

 

So, which would you buy? Stairville at 47 pounds, showtec at 53 or eurolite at 53?

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idly (>50Hz ideally several 100Hz). However some posts mention noticing a flicker when the brightness is very low. Does anyone know what frequency is being used for PWM?

 

Showtec 151 LED PAR 6 DMX channels, uses single Atmel chip for DMX in via 75176 and PWM control, rate is about 70Hz, which is a at times noticable flicker

 

6 Channels are

1,2,3 RGB intensity 0-255

4 Macro 1-15 off 16-255 macro on

5 Strobe speed 0-15 off 16-255 16 preset speeds

6 macro functions including set to s/l

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So, which would you buy? Stairville at 47 pounds, showtec at 53 or eurolite at 53?

Well I'm guessing that they all came out of the same factory, maybe with slightly differing firmware, but in reality there is probably no difference between them if all your going to use is the RGB channels. So based on that I'd buy the cheapest.

 

Ben

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I agree. Buy the cheapest! I also very much doubt that there are any versions with 4 channels. It is my understanding that they are either 5 or 6 though all online specs I have read will quote 4.

 

Anyhoo, late but as promised here are photos of the internals. Apologies for the size. I'm not sure if they are of any use given poor camera operator, light and jpegged, but there you go!

 

http://img86.imageshack.us/img86/7695/ledparbi3.jpg

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Its nice that the controller chip, probably a PIC, is socketed; this leaves the possibility of someone soewhere writing new firmware that would not have any of the reported flickering problems. and maybe a higher PWM rate.
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"Musht" said that the chip was an Atmel AVR (not a PIC).

I would be very interested to know what the chip numbers of the two chips and the speed of the crystal are.

 

If the micro isn't already an ATTiny2313 or it's running at 8MHz then an upgrade to 16MHz could solve the flicker issues.

 

Given that the second chip is probably looking after reading the DMX I fail to see why the PWM is as slow as 70Hz.

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From the pictures there are three chips, 8, 14 and 20 pins.

 

a 75176 would be the 8 pin (responsible for the DMX) marked as "U1" on the board.

a LM324 would be the 14 pin (it's a quad op-amp, probably responsible for the sound input) marked as "U3" on the board.

What is the 20 pin (the socketed chip with the big "V2" label over it)? Thats the microcontroller responsible for the whole thing (the chip that needs upgraded to get rid of the flicker).

 

EDIT: to add board names for U1 and U3

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What is the 20 pin (the socketed chip with the big "V2" label over it)? Thats the microcontroller responsible for the whole thing (the chip that needs upgraded to get rid of the flicker).
In the unit I looked in was definatley an Atmel AVR ,er, something.
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I think you'll find the little Atmel processors are pin compatible with PICs

I'm an AVR person, not a PIC person so I would want to replace it with another AVR (or just a software upgrade if they've done something terrible like use basic instead of 'C').

The AVRs and PICs may have their power to the same pins but probably not their PWM output capable pins etc.

 

It could be as simple as dropping in an AVR running at 16MHz rather than 8MHz to give lots of extra clock cycles to sort out the flicker on the PWM.

 

If It wasn't for the fact I'm stuck in the USA at the minute (with limited home-lab facilities) I would get one of these to do some firmware playing/re-design.

 

Edit: It appears there may be a market for "chipped" versions of these units http://www.btinternet.com/~Boxzone/Other/Smilies/Smilie_wink.gif

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Where did I get 324 from....schmitt trigger sounds better for bass trigger, will check that aren`t 2 types of PCB floating around when get chance. Pretty sure U1 was 75176 but will check.

 

Could see some demand for a retrofit chip with alternative firmware, >100hz PWM would really help.

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