Fantastic Atom Expander

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Here is the schematic, PC board pattern, and parts placement for a "Fantastic Atom Expander". This circuit produces an "exploding atom" effect using 98 LEDs.


This is the schematic of the Fantastic Atom Expander

PC Board Layout

This is the printed circuit layout for the Fantastic Atom Expander

Parts Placement

This is the parts placement for the Fantastic Atom Expander


Total Qty.
C110.1uf Mylar Capacitor0.1uF Ceramic Disc Capacitor
IC114017 IC
IC21555 Timer IC
L1-L9898Jumbo LED (any colour but blue)
Q1-Q552N3904 NPN Transistor
R114.7k Resistor
R21680k Resistor
R3-R74470 Ohm Resistor
MISC1PC Board, 9V Battery Snap, IC Sockets


  1. The LEDs can be any colour but blue. For a very interesting effect, make one ring red, the next one green, the next one orange, then yellow, etc.
  2. The transistors can be most any inexpensive NPN transistor (2N2222, PN2222A, Etc.).
  3. For a very interesting (and expensive!) effect, replace the 2N3904's with 2N3055 power transistors on heatsinks and use 12 V 500ma incandescent bulbs instead of LEDs.

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Add A Comment

Fantastic Atom Expander
Thursday, January 29, 2015 11:49:45 PM
This schematic is wrong, first they are connecting the pins 1-7 and other pins, they are already connected inside the 4017B chip, most retarded thing in the schematic, then transistors are flipped in the wrong direction, Most stupid thing ever "" PIN 13,15 are going to the ground but they are also resetting the chip "" WTF is that if you look in the 4017B datasheet you can see the gates and all the connections there ( functions of all the pins ).

(Editor's notes: 1 and 7 (etc.) are not connected internally. They are connected in the schematic to reduce the number of outputs while still providing a smooth count. The transistors are not backwards. Pin 13, etc. are tied to ground to prevent them from floating.)

Fantastic Atom Expander
Sunday, February 10, 2013 6:18:05 AM
Verry lousy schematic do it right or do nothing att all!!!!!!
Fantastic Atom Expander
Sunday, May 27, 2012 5:41:48 AM
verry rare .bad drauwing circuit and layout not logic
Fantastic Atom Expander
Sunday, August 02, 2009 5:20:54 PM
J means Jumper
Fantastic Atom Expander
Thursday, April 16, 2009 10:34:22 AM
What yhe J letter means? It appears like J1, J2, J3, J4, J5 and J6! Thanks!
Joćo Silva Brito
Fantastic Atom Expander
Thursday, April 16, 2009 9:59:32 AM
It's just me or its missing from the parts placement de led place or number 85. From my count is 97 leds not 98!?!? Please advise!
Joćo Silva Brito
Fantastic Atom Expander
Thursday, April 16, 2009 7:02:54 AM
Hello! Could you please send me or improve the showned Schematic because i can't see all the numbers in the ICs. It's really important! Thank's!
Fantastic Atom Expander
Friday, January 23, 2009 10:38:13 AM
Is it a one-shot deal, or does it provide a continuous series of expanding light effect ? Thanks
Fantastic Atom Expander
Tuesday, October 14, 2008 12:41:35 AM
circuit diagram is not clear
Fantastic Atom Expander
Wednesday, April 23, 2008 12:59:36 AM
I built my atom expander following the design on this page. But it didn't work at first because the capacitor was to small. Eventully after trying many capacitors a 220pf(0.22uf) worked and gave me a working project. So i don't know what happend, everything else is right it was just the capacitor. oh well, anybody building the project, if it doesn't work and the ic's are working make the capacitor a bit bigger like a 220pf.
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