diff --git a/pulsecircle.lua b/pulsecircle.lua
new file mode 100644
index 0000000..58b0fbe
--- /dev/null
+++ b/pulsecircle.lua
@@ -0,0 +1,99 @@
+COOLDOWN_FACTOR = 0.9998
+FADE_FACTOR = 0.985
+
+num_modules = 20
+center_module = 10
+
+-- maximum energy values for each band
+maxRedEnergy = 1
+maxGreenEnergy = 1
+maxBlueEnergy = 1
+
+-- output color buffers
+red = {}
+green = {}
+blue = {}
+
+tmpRed = {}
+tmpGreen = {}
+tmpBlue = {}
+
+function periodic()
+  local redEnergy = get_energy_in_band(0, 400);
+  local greenEnergy = get_energy_in_band(400, 4000);
+  local blueEnergy = get_energy_in_band(4000, 22000);
+  local centerIndex = 2 * center_module + 1;
+
+  maxRedEnergy = maxRedEnergy * COOLDOWN_FACTOR
+  if redEnergy > maxRedEnergy then
+    maxRedEnergy = redEnergy
+  end
+
+  maxGreenEnergy = maxGreenEnergy * COOLDOWN_FACTOR
+  if greenEnergy > maxGreenEnergy then
+    maxGreenEnergy = greenEnergy
+  end
+
+  maxBlueEnergy = maxBlueEnergy * COOLDOWN_FACTOR
+  if blueEnergy > maxBlueEnergy then
+    maxBlueEnergy = blueEnergy
+  end
+
+  -- move the color buffers on by one
+  for i = num_modules-1,1,-1 do
+    tmpRed[i+1]   = FADE_FACTOR * tmpRed[i]
+    tmpGreen[i+1] = FADE_FACTOR * tmpGreen[i]
+    tmpBlue[i+1]  = FADE_FACTOR * tmpBlue[i]
+  end
+
+  -- set the new value for the center module
+  newRed = redEnergy / maxRedEnergy
+  if newRed > tmpRed[num_modules] then
+    tmpRed[1] = newRed
+  else
+    tmpRed[1] = tmpRed[num_modules]
+  end
+
+  newGreen = greenEnergy / maxGreenEnergy
+  if newGreen > tmpGreen[num_modules] then
+    tmpGreen[1] = newGreen
+  else
+    tmpGreen[1] = tmpGreen[num_modules]
+  end
+
+  newBlue = blueEnergy / maxBlueEnergy
+  if newBlue > tmpBlue[num_modules] then
+    tmpBlue[1] = newBlue
+  else
+    tmpBlue[1] = tmpBlue[num_modules]
+  end
+
+  for i = 1,num_modules do
+    red[i] = tmpRed[i]
+    green[i] = tmpGreen[i]
+    blue[i] = tmpBlue[i]
+  end
+
+  -- return the 3 color arrays
+  return red, green, blue
+end
+
+function init(nmod, cmod)
+  num_modules = nmod
+  center_module = cmod
+
+  for i = 1,nmod do
+    red[i] = 0
+    green[i] = 0
+    blue[i] = 0
+  end
+
+  for i = 1,nmod do
+    tmpRed[i] = 0
+    tmpGreen[i] = 0
+    tmpBlue[i] = 0
+  end
+
+  -- don't use fading
+  return 0
+end