tough for some microcontrollers. In the case of PICAXE
Basic, the pauseus command only pauses in 10s of
microseconds. So, a pauseus 2 is really a 20 microsecond
pause. At one point, I needed a pause for 72
microseconds and the closest pause (without going under)
was pauseus 8 for 80 microseconds. All the timing in
Figure 4 is the minimum;
larger delays can be
used. The sample code
for reading three of the
seven bands is shown in
subroutine selects the
jaw’s band by skipping
or getting the bands in
order, and opens the jaw
if it detects a tone. If the
subroutine is called 30
or more times a second,
then the skulls will stay in sync with the music.
In the years since I built the original Trio of Singing
Skulls, I’ve created a line of controllers for the haunt
industry. My Thor 2 Thunder and Lighting control has all
the parts (but one) needed to run the new singing skulls.
Of course, the missing part is the MSGEQ7 chip.
While the MSGEQ7P (“PDIP” version) runs from $2
to $5 depending on the source, I opted for the “N”
surface-mount version on a $12 breakout board from a
vender on eBay (see Figure 8). This made it easy to
mount and hook up the MSGEQ7 to the Thor 2 board
In no time, the new version of the Trio of Singing
Skulls was up and running. I really like how clean and
compact this new version turned out. Best of all, there is
no more drift in the analog tone detection circuit from hot
36 September 2015
FIGURE 8. MSGEQ7N breakout board.
FIGURE 9. New controller with MSGEQ7N breakout board.
Singing Trio video
PICAXE IDE and manuals
Thor 2 and Banshee controllers
eBay.com and SparkFun.com
MSGEQ7N breakout board