3. Solder all of the remaining anode pins together.
This anode pin bus will be connected to V+ during a
4. Turn the LM3914 over and upside down (i.e., “dead
bug”). Nest the IC neatly between the anode pin bus and
the cathode pins.
5. Carefully solder pins 18-11 of the LM3914 to the
adjacent cathode pins. These cathode pins are for LED 2
through LED 9.
6. Solder pin 1 on the LM3914 to the LED 1 cathode.
Now, LEDs 1-9 on the LED bar graph are connected to the
7. Solder pins 6 and 7 on the LM3914 together, then
connect a 1K resistor between these joined pins and
8. Connect the LM3914’s pins 8, 4, and 2 to GND.
9. If you don’t like the dot mode display for the
desktop rocket, you can optionally connect pin 9 on the
LM3914 to V+. This connection will enable bar mode
display on the LED bar graph. In bar mode, all LEDs
remain lit as the potentiometer is turned.
10. The signal source input is provided by the 5K
potentiometer. The middle wiper contact on the
potentiometer is connected to pin 5 on the LM3914. One
of the two remaining potentiometer contacts is soldered
to V+ and the final contact is soldered to GND.
11. Carefully push the two blinking LEDs through the
cardboard rocket’s nosecone. The anodes of the LEDs are
both connected to V+, whereas the cathodes of the
blinking LEDs are connected to pin 10 of the LM3914.
12. The final step is to add the battery power. All
GND connections are routed to the negative terminal (-)
■ The "business" end of the desktop rocket without
lighting any fuses. Note: The LM3914 is fixed upside
down and "dead bug" between the cathode/anode
pin rows of the LED bar graph.
■ Light up your life with desktop fireworks.
46 July 2014