Every visit to the Exploratorium results in going home and building something

Which is an awesome thing, taking home the inspiration to build my very own beats bringing something back from the gift shop.

Years ago I did the orbital simulator.

This is an implementation of the colored room using simple LM317 (NTE 956 obtained at Fry's) as current limiter. The hight brightness LEDs and 100k Potentiometers were obtained at Halted. The wooden knobs were hand crafted. Power is provided by a ultrafire 3.7 volt lithium ion battery ordered from amazon. The red LED was way too bright so a series resistor was put in to keep it in line with the green and blue LEDs. Even so, the beam width is too wide compared to the other two.

A small wooden board. Above it is circuitry, a battery, three raised wooden knobs colored green, red, and blue, and three red, green, and blue LEDs on the right. Previous image but LEDs are facing viewer Previous image but rotated around 90 degrees cllockwise First image but focusing on LEDs A precision current limiter schematic but horribly copied into an svg file original image

On the way to trying to use the 555 Timer chip to do PWM (Pulsed Width Modulation) for dimming the LEDs as an alternative to using LM317, I found this site and just could not resist building the fade up and down circuit. Years ago I saw a mac laptop in sleep mode in a store demo that had the snoozing white power LED. It was an intuitive UI, especially compared to a hard blinking power LED on a Wintel laptop. Always wanted to build a circuit like that.

Changes from the design (modified values shown in schematic below):

To make the fade gentler, the charging / discharging cap was increased from 220uF to 470uF. The LED chosen was a blue one, so the in line resistor was reduced from 470ohm to 220ohm. The timing POT was increased to 100k to give a wider range. It goes from faster than human eye perception to several minutes between cycles. Power is provided by 4 x 1.5 volt AA (carbon zinc)

Everything is enclosed in a Blue Diamond Honey Roasted Almond can. As you can see in the last picture, it would have done better if the lid was reinforced.

Once again, dead-bug style, but on a 16-pin socket. The blue LED's light is shrine thru half a glue stick.

A can with a wooden knob and small cylinder emanating blue light above it Previous image but the can's cover is raised slightly revealing circuitry and battery Previous image but zoom in to circuitry Closed can with circuitry extracted Zoom in to previous image Zoom in to previous image Light can with cover fully removed Fading LED schematic but horribly copied into an svg file original image

A bright young mind suggested another copy be built using an amber LED so he can put it in his jack-o-lantern for halloween, planned changes include 1000uF fade cap, CMOS version of 555 for use with 2 x AA power, amber LED of course, with 100ohm series resistor for use with lower voltage supply and LED consumption. Will try to use a smaller enclosure, vitamin bottle maybe. This dead bug will not have a socket, which is twisted, because the CMOS can use a socket more than the regular 555.

red blue green red

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