diff --git a/basic_machines/funnel.lua b/basic_machines/funnel.lua
index 2663d2b..c31b16d 100644
--- a/basic_machines/funnel.lua
+++ b/basic_machines/funnel.lua
@@ -101,6 +101,7 @@ minetest.register_node("techage:ta3_funnel", {
 	},
 
 	drawtype = "nodebox",
+	paramtype = "light",
 	node_box = {
 		type = "fixed",
 		fixed = {
diff --git a/basic_machines/gravelrinser.lua b/basic_machines/gravelrinser.lua
index 05720e5..12ee439 100644
--- a/basic_machines/gravelrinser.lua
+++ b/basic_machines/gravelrinser.lua
@@ -250,6 +250,7 @@ local tubing = {
 local node_name_ta2, node_name_ta3, node_name_ta4 = 
 	techage.register_consumer("rinser", S("Gravel Rinser"), tiles, {
 		drawtype = "nodebox",
+		paramtype = "light",
 		node_box = {
 			type = "fixed",
 			fixed = {
diff --git a/basic_machines/gravelsieve.lua b/basic_machines/gravelsieve.lua
index 4e52816..61fa1e6 100644
--- a/basic_machines/gravelsieve.lua
+++ b/basic_machines/gravelsieve.lua
@@ -187,6 +187,7 @@ local tubing = {
 local node_name_ta2, node_name_ta3, node_name_ta4 = 
 	techage.register_consumer("gravelsieve", S("Gravel Sieve"), tiles, {
 		drawtype = "nodebox",
+		paramtype = "light",
 		node_box = {
 			type = "fixed",
 			fixed = {
diff --git a/basic_machines/grinder.lua b/basic_machines/grinder.lua
index 09e8d2a..285e94d 100644
--- a/basic_machines/grinder.lua
+++ b/basic_machines/grinder.lua
@@ -193,6 +193,7 @@ local tubing = {
 local node_name_ta2, node_name_ta3, node_name_ta4 = 
 	techage.register_consumer("grinder", S("Grinder"), tiles, {
 		drawtype = "nodebox",
+		paramtype = "light",
 		node_box = {
 			type = "fixed",
 			fixed = {
diff --git a/doc/ta4_doc.lua b/doc/ta4_doc.lua
new file mode 100644
index 0000000..b2c5c43
--- /dev/null
+++ b/doc/ta4_doc.lua
@@ -0,0 +1,56 @@
+--[[
+
+	TechAge
+	=======
+
+	Copyright (C) 2019 Joachim Stolberg
+
+	GPL v3
+	See LICENSE.txt for more information
+	
+	Main module for the in-game TA4documentation
+
+]]--
+
+local S = techage.S
+
+techage.register_category_page("ta4", 
+	S("Future Age (TA4)"),
+	S("The Future Age is the forth level of the available technic stages.@n"..
+		"The goal of TA4 is to operate your machines only with renewable energy.@n"..
+		"Build wind turbines, solar panel plants and biogas plants and use@n"..
+		"future technologies."),
+	"techage:ta4_wlanchip", 
+	{}
+)
+
+
+local ROTOR = "techage_wind_turbine_inv.png"
+local CANELLE = "techage_rotor.png"
+local PILLAR = "techage_pillar_inv.png"
+
+local Images = {
+	{false, false, false, ROTOR, CANELLE, false, false},
+	{false, false, false, PILLAR, false,  false, false},
+	{false, false, false, PILLAR, false,  false, false},
+	{false, false, false, PILLAR, false,  false, false},
+	{false, false, false, PILLAR, false,  false, false},
+	{false, false, false, PILLAR, false,  false, false},
+	{false, false, false, PILLAR, false,  false, false},
+	{false, false, false, PILLAR, false,  false, false},
+}
+
+--techage.register_entry_page("ta3", "power_station",
+techage.register_category_page("ta4wt",
+	S("TA4: Wind Turbine"), 
+	S("Build a Wind Turbine according to the plan with TA4 Wind Turbine, TA4 Wind Turbine Nacelle and@n"..
+		"a pillar by means of TA4 Pillar nodes (power cables have to be inside).@n"..
+		"Please note the following limitations:@n"..
+		"- pillar height between 10 and 19 m@n"..
+		"- can only be built offshore (the info tool indicates where a wind turbine can be built)@n"..
+		"- 14 m free space in all 4 directions (e.g. to the next wind turbine)@n"..
+		"- the wind blows only between 5 and 9 o'clock and between 17 and 21 o'clock"), 
+	nil, 
+	{},
+	Images)
+
diff --git a/init.lua b/init.lua
index 463a99b..44feb52 100644
--- a/init.lua
+++ b/init.lua
@@ -47,6 +47,7 @@ else
 	dofile(MP.."/doc/ta1_doc.lua")
 	dofile(MP.."/doc/ta2_doc.lua")
 	dofile(MP.."/doc/ta3_doc.lua")
+	dofile(MP.."/doc/ta4_doc.lua")
 	
 	-- Nodes1
 	dofile(MP.."/nodes/baborium.lua")
@@ -181,4 +182,5 @@ else
 	-- Wind
 	dofile(MP.."/wind_turbine/rotor.lua")
 	dofile(MP.."/nodes/pillar.lua")
+	dofile(MP.."/wind_turbine/signallamp.lua")
 end
\ No newline at end of file
diff --git a/nodes/pillar.lua b/nodes/pillar.lua
index 08e5644..45c48c8 100644
--- a/nodes/pillar.lua
+++ b/nodes/pillar.lua
@@ -23,9 +23,17 @@ minetest.register_node("techage:pillar", {
 		type = "fixed",
 		fixed = {-8/32, -16/32, -8/32, 8/32, 16/32, 8/32},
 	},
-
+	backface_culling = true,
 	groups = {cracky=1},
 	on_rotate = screwdriver.disallow,
 	is_ground_content = false,
 	sounds = default.node_sound_stone_defaults(),
 })
+
+
+
+minetest.register_craft({
+	type = "shapeless",
+	output = "techage:pillar",
+	recipe = {"basic_materials:concrete_block"},
+})
diff --git a/textures/techage_carbon_fiber.png b/textures/techage_carbon_fiber.png
new file mode 100644
index 0000000..93e8e22
Binary files /dev/null and b/textures/techage_carbon_fiber.png differ
diff --git a/textures/techage_epoxy.png b/textures/techage_epoxy.png
new file mode 100644
index 0000000..d4db6e8
Binary files /dev/null and b/textures/techage_epoxy.png differ
diff --git a/textures/techage_pillar_inv.png b/textures/techage_pillar_inv.png
new file mode 100644
index 0000000..bb2ea62
Binary files /dev/null and b/textures/techage_pillar_inv.png differ
diff --git a/textures/techage_rotor.png b/textures/techage_rotor.png
index 20e2f0d..84faa56 100644
Binary files a/textures/techage_rotor.png and b/textures/techage_rotor.png differ
diff --git a/textures/techage_rotor_blade.png b/textures/techage_rotor_blade.png
new file mode 100644
index 0000000..aba770d
Binary files /dev/null and b/textures/techage_rotor_blade.png differ
diff --git a/textures/techage_rotor_blades.png b/textures/techage_rotor_blades.png
index d2895f8..eaffea3 100644
Binary files a/textures/techage_rotor_blades.png and b/textures/techage_rotor_blades.png differ
diff --git a/textures/techage_rotor_lamp_off.png b/textures/techage_rotor_lamp_off.png
new file mode 100644
index 0000000..a689f0b
Binary files /dev/null and b/textures/techage_rotor_lamp_off.png differ
diff --git a/textures/techage_rotor_lamp_on.png b/textures/techage_rotor_lamp_on.png
new file mode 100644
index 0000000..63e80a7
Binary files /dev/null and b/textures/techage_rotor_lamp_on.png differ
diff --git a/textures/techage_rotor_top.png b/textures/techage_rotor_top.png
index ae1b34d..93f3b1d 100644
Binary files a/textures/techage_rotor_top.png and b/textures/techage_rotor_top.png differ
diff --git a/wind_turbine/rotor.lua b/wind_turbine/rotor.lua
index a0c2fe7..db0c04a 100644
--- a/wind_turbine/rotor.lua
+++ b/wind_turbine/rotor.lua
@@ -46,30 +46,40 @@ local function pos_and_yaw(pos, param2)
 	return pos, {x=0, y=yaw, z=0}
 end
 
-local function add_rotor(pos, player_name)
-	local pos1 = {x=pos.x-14, y=pos.y-10, z=pos.z-14}
+local function add_rotor(pos, mem, player_name)
+	mem.error = false
+	local pos1 = {x=pos.x-14, y=pos.y-9, z=pos.z-14}
 	local pos2 = {x=pos.x+14, y=pos.y+10, z=pos.z+14}
-	local num_node = 29*29*21 - 12
+	local num_node = 29*29*20 - 12
 	local num = #minetest.find_nodes_in_area(pos1, pos2, {"air", "ignore"})
 	if num < num_node then
 		if player_name then
-			minetest.chat_send_player(player_name, "[TA4 Wind Turbine] Not enough space!")
+			minetest.chat_send_player(player_name, S("[TA4 Wind Turbine]")..
+				" "..S("Not enough space!"))
 		end
+		M(pos):set_string("infotext", S("TA4 Wind Turbine").." "..S("Error"))
+		mem.error = true
 		return
 	end
 	
 	local data = minetest.get_biome_data({x=pos.x, y=0, z=pos.z})
 	if not techage.OceanIdTbl[data.biome] then
 		if player_name then
-			minetest.chat_send_player(player_name, "[TA4 Wind Turbine]  Wrong place for wind turbines!")
+			minetest.chat_send_player(player_name, S("[TA4 Wind Turbine]")..
+				" "..S("Wrong place for wind turbines!"))
 		end
+		M(pos):set_string("infotext", S("TA4 Wind Turbine").." "..S("Error"))
+		mem.error = true
 		return
 	end
 	
 	if pos.y < 12 or pos.y > 20 then
 		if player_name then
-			minetest.chat_send_player(player_name, "[TA4 Wind Turbine] No wind at this altitude!")
+			minetest.chat_send_player(player_name, S("[TA4 Wind Turbine]")..
+				" "..S("No wind at this altitude!"))
 		end
+		M(pos):set_string("infotext", S("TA4 Wind Turbine").." "..S("Error"))
+		mem.error = true
 		return
 	end
 	
@@ -85,6 +95,14 @@ local function add_rotor(pos, player_name)
 end	
 
 local function start_rotor(pos, mem)
+	local npos = techage.get_pos(pos, "F")
+	local node = minetest.get_node(npos)
+	if node.name ~= "techage:ta4_wind_turbine_nacelle" then
+		M(pos):set_string("infotext", S("TA4 Wind Turbine").." "..S("Error"))
+		mem.error = true
+		return
+	end
+	
 	mem.providing = true
 	power.generator_start(pos, mem, PWR_PERF)
 	local hash = minetest.hash_node_position(pos)
@@ -105,7 +123,6 @@ end
 local function node_timer(pos, elapsed)
 	local mem = tubelib2.get_mem(pos)
 	
-	print("node_timer", mem.running, mem.providing)
 	if not mem.running then
 		return false
 	end
@@ -148,7 +165,7 @@ minetest.register_node("techage:ta4_wind_turbine", {
 		meta:set_string("infotext", S("TA4 Wind Turbine").." "..own_num)
 		mem.providing = false
 		mem.running = true
-		add_rotor(pos, placer:get_player_name())
+		add_rotor(pos, mem, placer:get_player_name())
 		minetest.get_node_timer(pos):start(CYCLE_TIME)
 	end,
 	
@@ -206,7 +223,9 @@ techage.register_node({"techage:ta4_wind_turbine"}, {
 		local mem = tubelib2.get_mem(pos)
 		print("on_recv_message", topic)
 		if topic == "state" then
-			if mem.running and mem.providing then
+			if mem.error then
+				return "error"
+			elseif mem.running and mem.providing then
 				return "running"
 			else
 				return "stopped"
@@ -220,19 +239,67 @@ techage.register_node({"techage:ta4_wind_turbine"}, {
 		end
 	end,
 	on_node_load = function(pos)
-		add_rotor(pos)
 		local mem = tubelib2.get_mem(pos)
+		add_rotor(pos, mem)
 		mem.providing = false  -- to force the rotor start
 		minetest.get_node_timer(pos):start(CYCLE_TIME)
 	end,
 })
 
+minetest.register_craftitem("techage:ta4_epoxy", {
+	description = S("TA4 Epoxide Resin"),
+	inventory_image = "techage_epoxy.png",
+})
 
---minetest.register_craft({
---	output = "techage:ta4_wind_turbine",
---	recipe = {
---		{"", "techage:ta4_wlanchip", ""},
---		{"techage:ta4_silicon_wafer", "techage:ta4_silicon_wafer", "techage:ta4_silicon_wafer"},
---		{"default:tin_ingot", "techage:iron_ingot", "default:copper_ingot"},
---	},
---})
+minetest.register_craftitem("techage:ta4_carbon_fiber", {
+	description = S("TA4 Carbon Fiber"),
+	inventory_image = "techage_carbon_fiber.png",
+})
+
+minetest.register_craftitem("techage:ta4_rotor_blade", {
+	description = S("TA4 Rotor Blade"),
+	inventory_image = "techage_rotor_blade.png",
+})
+
+
+minetest.register_craft({
+	output = "techage:ta4_wind_turbine",
+	recipe = {
+		{"dye:white", "techage:ta4_rotor_blade", "dye:red"},
+		{"basic_materials:gear_steel", "techage:generator", "basic_materials:gear_steel"},
+		{"techage:ta4_rotor_blade", "techage:electric_cableS", "techage:ta4_rotor_blade"},
+	},
+})
+
+minetest.register_craft({
+	output = "techage:ta4_wind_turbine_nacelle",
+	recipe = {
+		{"default:steel_ingot", "", "default:steel_ingot"},
+		{"dye:white", "techage:ta4_wlanchip", "dye:red"},
+		{"", "default:copper_ingot", ""},
+	},
+})
+
+minetest.register_craft({
+	output = "techage:ta4_rotor_blade",
+	recipe = {
+		{"techage:ta4_carbon_fiber", "dye:white", "techage:ta4_carbon_fiber"},
+		{"techage:ta4_epoxy", "techage:ta4_carbon_fiber", "techage:ta4_epoxy"},
+		{"techage:ta4_carbon_fiber", "dye:red", "techage:ta4_carbon_fiber"},
+	},
+})
+
+techage.furnace.register_recipe({
+	output = "techage:ta4_carbon_fiber", 
+	recipe = {"default:papyrus", "default:stick", "default:papyrus", "default:stick"}, 
+	heat = 4,
+	time = 3,
+})
+
+techage.furnace.register_recipe({
+	output = "techage:ta4_epoxy", 
+	recipe = {"basic_materials:oil_extract", "techage:oil_source", 
+		"basic_materials:oil_extract", "techage:oil_source"}, 
+	heat = 4,
+	time = 3,
+})
diff --git a/wind_turbine/signallamp.lua b/wind_turbine/signallamp.lua
new file mode 100644
index 0000000..ef5aeec
--- /dev/null
+++ b/wind_turbine/signallamp.lua
@@ -0,0 +1,108 @@
+--[[
+
+	TechAge
+	=======
+
+	Copyright (C) 2019 Joachim Stolberg
+
+	GPL v3
+	See LICENSE.txt for more information
+
+	Colored Signal Lamp (requires unifieddyes)
+	
+]]--
+
+-- for lazy programmers
+local M = minetest.get_meta
+local S = techage.S
+
+local logic = techage.logic
+
+local COLORED = minetest.get_modpath("unifieddyes") and minetest.global_exists("unifieddyes")
+
+
+local function switch_on(pos, node)
+	node.name = "techage:signal_lamp_on"
+	minetest.swap_node(pos, node)
+end	
+
+local function switch_off(pos, node)
+	node.name = "techage:signal_lamp_off"
+	minetest.swap_node(pos, node)
+end	
+
+minetest.register_node("techage:rotor_signal_lamp_off", {
+	description = S("TA4 Wind Turbine Signal Lamp"),
+	tiles = {"techage_rotor_lamp_off.png"},
+	drawtype = "nodebox",
+    node_box = {
+		type = "fixed",
+		fixed = {
+			{-2/16, -8/16, -2/16,  2/16, -3/16, 2/16},
+		},
+	},
+
+	after_place_node = function(pos, placer, itemstack, pointed_thing)
+		minetest.get_node_timer(pos):start(2)
+	end,
+
+	on_timer = function(pos, elapsed)
+		minetest.swap_node(pos, {name = "techage:rotor_signal_lamp_on"})
+		return true
+	end,
+
+	paramtype = "light",
+	paramtype2 = "glasslikeliquidlevel",
+	sunlight_propagates = true,
+	sounds = default.node_sound_glass_defaults(),
+	groups = {cracky = 3, oddly_breakable_by_hand = 3},
+	is_ground_content = false,
+	drop = "techage:rotor_signal_lamp_off"
+})
+
+minetest.register_node("techage:rotor_signal_lamp_on", {
+	description = S("TA4 Wind Turbine Signal Lamp"),
+	tiles = {"techage_rotor_lamp_on.png"},
+	drawtype = "nodebox",
+    node_box = {
+		type = "fixed",
+		fixed = {
+			{-2/16, -8/16, -2/16,  2/16, -3/16, 2/16},
+		},
+	},
+
+	on_timer = function(pos, elapsed)
+		minetest.swap_node(pos, {name = "techage:rotor_signal_lamp_off"})
+		return true
+	end,
+	
+	paramtype = "light",
+	light_source = 8,
+	paramtype2 = "glasslikeliquidlevel",
+	sunlight_propagates = true,
+	sounds = default.node_sound_glass_defaults(),
+	groups = {cracky = 3, oddly_breakable_by_hand = 3, not_in_creative_inventory=1},
+	is_ground_content = false,
+	drop = "techage:rotor_signal_lamp_off"
+})
+
+minetest.register_lbm({
+	label = "Restart Lamp",
+	name = "techage:rotor_signal_lamp",
+	nodenames = {"techage:rotor_signal_lamp_on", "techage:rotor_signal_lamp_off"},
+	run_at_every_load = true,
+	action = function(pos, node)
+		minetest.get_node_timer(pos):start(2)
+	end,
+})
+
+
+minetest.register_craft({
+	output = "techage:rotor_signal_lamp_off",
+	recipe = {
+		{"", "dye:red", ""},
+		{"", "default:torch", ""},
+		{"", "default:glass", ""},
+	},
+})
+