Question on 3D Xmas trees
mikkail wrote 10/18/2019 at 07:42 • 0 pointsThere seem to be two flavours of these - 3 colour (red, green, yellow) and 7-colour. The 7-colour ones have leds that already have a chip inside to flash them; why do they need the same flash circuit the 3 colour ones use?
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Where does it say that on the second schematic that it has 7 colour LEDs? It just says white LEDs. Do you have a kit with a different schematic that you haven't shown us?
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Same schematic - just uses 7-colour LEDs. Here is a link: http://www.mindkits.co.nz/flashing-christmas-tree-kit.aspx
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I don't see any mention of colour on that page, let alone 7. Looks like just white LEDs. You see a little blue at times but that may be just a camcorder artefact.
What do you mean by 7 anyway? Each LED can display 7 colours, or there are 7 groups of coloured LEDs?
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You tube link: https://www.youtube.com/watch?v=_HpG79MojFw
Shows white LEDs - seem to be like these: https://www.sparkfun.com/products/11448
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I have a feeling that the Icstation description is misleading or a bad translation, and they are just white LEDs like the parts lists say. Let us know what you get in the kit.
The Sparkfun ones are not limited to 7 colours, they cycle through the RGB space so vary continuously. Who knows maybe you do get those but they are not flashing, they change gradually so there is no contradiction with using them in a ring oscillator circuit, although one would think each cycle of the oscillation would reset the LED and interrupt its progress through the colour space.
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It looks like the original kit version had either 3 different color leds, or 7 different color leds. Since, in the circuit, they are divided in three groups, you'd have to put leds with the same forward voltage in the same group.
It seems like you found a third variant of this circuit, where they use color changing leds. These tend to start at the color red, and then fade to green, blue and then red again. Depending on the flashing pattern this could result in a nice effect. For example, look at the Canton LED Tower Kit https://www.youtube.com/watch?v=D2a6ZTITga0
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Hi Gerben. Yes, it appears the 7-colour one uses the colour cycling LEDs. My query is why re-use a flashing circuit (I suspect the 3-colour one is the original) with LEDs that have their own flashing pattern? The only other change to the circuit is the resistors in series with the LEDs, since the 7-colour one uses LEDs with all the same forward voltage.
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My guess is that changing the PCB design was to expensive. So it's cheaper to only exchange the LEDs and the resistor values.
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This looks like an error in the description. These looks like the very same circuit. The first one with red, green and yellow LEDs cycling and the second one with 3 groups of white LEDs cycling. Guess you can swap out the white LEDs by some of other color. I have doubt if mixing different colors in on group is a particularly smart idea. As the tree has two circuits with 3 groups each 6 colors should not be a difficult thing to do. No idea where they get the 7th color from. May be mixing blue and white (which is also blue on the inside). Or counting the white LED on top.
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Hi Florian. Here is a link to a site that has the 7-colour kit with a demo showing it in operation:
http://www.mindkits.co.nz/flashing-christmas-tree-kit.aspx
I've ordered one of each for fun - I like the idea of putting a white LED ot the top for a star! :)
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Sorry - here is a link to the two schematics. Apart from the LEDs, the only other change is the value of the resistors in series with the LEDs.
https://1drv.ms/u/s!AsnsJOtKJueUgZpzt_pR1qt-RLCSxA?e=In8KQx
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Can you at least add some links to the parts you are talking about and the schematic of the circuit?
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Sorry - here is a link to the two schematics. Apart from the LEDs, the only other change is the value of the resistors in series with the LEDs.
https://1drv.ms/u/s!AsnsJOtKJueUgZpzt_pR1qt-RLCSxA?e=In8KQx
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