Halloween '14 pics!

fade

fade

Staff member
I made several other simple props. One of which @stienman helped me out with over at stack exchange. This mess is 8 pairs of lights designed to trigger in slow sequence and then fade out. Partly a turn signal circuit design and partly stuff I made up together myself. Part count got kind of high for something so simple but what can you do. There's a 555, a 741, an optocoupler (the fading needs higher V than the 555 can handle, and I couldn't put in another transistor without saturating the caps and losing the fade effect), a regulator, and a homemade IR proximity detector (which uses the 741 as a comparator--thanks Instructables). It's staying on a breadboard until after Halloween, because I want all those parts back.

Anyway, I'll be distributing them through bushes and ivy as eyes that light up when triggered.

On the plus side, between all these projects, I finally found a use for 150' of telephone wire I've been carting through 3 moves now...

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evilmike

evilmike

fade said:
I made several other simple props. One of which @stienman helped me out with over at stack exchange. This mess is 8 pairs of lights designed to trigger in slow sequence and then fade out. Partly a turn signal circuit design and partly stuff I made up together myself. Part count got kind of high for something so simple but what can you do. There's a 555, a 741, an optocoupler (the fading needs higher V than the 555 can handle, and I couldn't put in another transistor without saturating the caps and losing the fade effect), a regulator, and a homemade IR proximity detector (which uses the 741 as a comparator--thanks Instructables). It's staying on a breadboard until after Halloween, because I want all those parts back.

Anyway, I'll be distributing them through bushes and ivy as eyes that light up when triggered.

On the plus side, between all these projects, I finally found a use for 150' of telephone wire I've been carting through 3 moves now...

View attachment 16430 View attachment 16431
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It sounds like you've done a great job with everything.

Do you have a schematic posted for your fader circuit?
 
fade

fade

Staff member
drawn_inward said:
Hot damn @fade - Great work! Now, go make an Instructable post. :D
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Thanks. I would, but singing pumpkins and singing Christmas trees are pretty common. The only thing I could contribute really is my springy opening/closing mechanism. I think it adds a little life to them, so that they're not clomping away like pac-man.[DOUBLEPOST=1414506938,1414506422][/DOUBLEPOST]
evilmike said:
It sounds like you've done a great job with everything.

Do you have a schematic posted for your fader circuit?
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Here's a really nasty version I threw together on Digi-key's Schemeit site: http://www.digikey.com/schemeit/#12fx
 
fade

fade

Staff member
They are connected to one another. It's how the cascade works. Vbe rises according to the RC timer. Each transistor incurs an additional 0.7V drop, so each transistor doesn't open until the base voltage rises above the Vce, which is successively larger for each transistor. Therefore, each lights in succession. The first to light is the lowest one on the staircase there.[DOUBLEPOST=1414509707,1414509344][/DOUBLEPOST]Right, and don't forget the V drops from the LEDs, too. That changes Vce.
 
fade

fade

Staff member
Let me try that again. Imagine the rising V from the RC on Q8. When it hits 0.7V, Q8 opens, and the first LEDs come on. But the emitter of Q7 is also at 0.7V, so Q7 won't open until it the RC circuit reaches 1.4V, which puts the emitter of Q6 at 1.4V, so Q6 won't open until the RC hits 2.1V, etc, etc. Actually, this is only accurate for the Q8. After that, the emitter voltage contains some of Vce divided by any realistically non-zero resistance across all the b-e paths below the transistor of interest. So it means that you need more than 0.7*8 = 5.6V to open all 8 transistors.

Also, note there's no discharge path for the 940uf capacitance. I left it out because it makes the LEDs go out really slowly as the caps discharge whatever way they can. Probably not healthy for the circuit, but whatever. It's for a couple of hours one night.
 
Dei

Dei

I should theoretically trim and re-hem my Elsa dress because it is way too long, but I don't know if I have the will in me to do so. Have to finish the cape part of my daughter's costume today because she will probably want it for trick or treating time, and I have to drum up the urge to carve pumpkins after spending the better part of the month making 2 costumes. If only my husband wasn't so blase about holidays, I could pawn off the pumpkin carving on him. But he did spend 3-4 hours helping me cut out the stencils for my daughter's costume so I can't get too mad.
 
fade

fade

Staff member
I know that feel. I had like 5 other electronic props I wanted to make, and I had time last night. But I was like, nope. I spent dawn till dusk this weekend on those pumpkins. Ditto on the spouse, too. My wife's attitude is, "Meh, Halloween".
 
Shakey

Shakey

We tried to do pumpkins last night, but no one had any pumpkins left. So, I thought what the heck, let's try carving these little pie pumpkins. Not a good idea... They are hard as hell. We broke 4 carving knives trying to do it.
 
Celt Z

Celt Z

Dei said:
I should theoretically trim and re-hem my Elsa dress because it is way too long, but I don't know if I have the will in me to do so. Have to finish the cape part of my daughter's costume today because she will probably want it for trick or treating time, and I have to drum up the urge to carve pumpkins after spending the better part of the month making 2 costumes. If only my husband wasn't so blase about holidays, I could pawn off the pumpkin carving on him. But he did spend 3-4 hours helping me cut out the stencils for my daughter's costume so I can't get too mad.
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You're doing a great job! The costumes look wonderful! But I know what you mean about wishing you could share the workload. Mr. Z is always willing to help me put up decorations and happy to buy supplies, but asking him to make something (like pumpkin carving) is like saying, "Here, could you hack this to pieces? Thanks!". The man is handy, but has no artistic gene.
 
Dei

Dei

Fucked up cutting something. Fabric store no longer has same shade of my fleece color. Needed to rebuy all fleece to recut everything. /headdesk /headdesk.
 
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