diff --git a/README.md b/README.md
index e00e840..8f37558 100644
--- a/README.md
+++ b/README.md
@@ -21,9 +21,10 @@ Feel free to use this project as a base for your own projects AT YOUR OWN RISK!
 - ESP32 board Wemos Lolin32
 - OLED 128x64 with controller SH1106 at I2C
 - Voltage supply from either USB or power supply or 3x 1.5V AAA batteries, circuit works stable from 3.0 V up to 5.0 V
-- Pulse input is expected at GPIO 18 (high pulses with at least about 250 µs length)
+- Pulse input is expected at GPIO 15 (high pulses with at least about 250 µs length)
 - Switch for WiFi mode is expected at GPIO 4 (low=WiFi mode, high=low-power mode)
 - OLED I2C bus is expected at GPIO 22 (SCK) and 21 (SDA)
+- Pins may be adjusted in `main.cpp`
 
 # Software
 
diff --git a/hardware/kicad/project/geiger/geiger.sch b/hardware/kicad/project/geiger/geiger.sch
index 9dc9d1a..e7c4f81 100644
--- a/hardware/kicad/project/geiger/geiger.sch
+++ b/hardware/kicad/project/geiger/geiger.sch
@@ -5,7 +5,7 @@ $Descr A4 11693 8268
 encoding utf-8
 Sheet 1 1
 Title "ESP32 Geiger Counter"
-Date "2021-01-30"
+Date "2021-03-07"
 Rev ""
 Comp "Holger Fleischmann"
 Comment1 ""
@@ -778,38 +778,38 @@ Wire Wire Line
 $Comp
 L Device:R R12
 U 1 1 602C68B9
-P 1650 6600
-F 0 "R12" V 1750 6600 50  0000 C CNN
-F 1 "3k3" V 1534 6600 50  0000 C CNN
-F 2 "" V 1580 6600 50  0001 C CNN
-F 3 "~" H 1650 6600 50  0001 C CNN
-	1    1650 6600
+P 1900 6200
+F 0 "R12" V 2000 6200 50  0000 C CNN
+F 1 "3k3" V 1784 6200 50  0000 C CNN
+F 2 "" V 1830 6200 50  0001 C CNN
+F 3 "~" H 1900 6200 50  0001 C CNN
+	1    1900 6200
 	0    1    1    0   
 $EndComp
 $Comp
 L Device:D_Zener D5
 U 1 1 602C754E
-P 1900 6850
-F 0 "D5" V 1854 6930 50  0000 L CNN
-F 1 "3V3" V 1945 6930 50  0000 L CNN
-F 2 "" H 1900 6850 50  0001 C CNN
-F 3 "~" H 1900 6850 50  0001 C CNN
-	1    1900 6850
+P 2150 6450
+F 0 "D5" V 2104 6530 50  0000 L CNN
+F 1 "3V3" V 2195 6530 50  0000 L CNN
+F 2 "" H 2150 6450 50  0001 C CNN
+F 3 "~" H 2150 6450 50  0001 C CNN
+	1    2150 6450
 	0    1    1    0   
 $EndComp
-Text GLabel 1300 6600 0    50   Input ~ 0
+Text GLabel 1550 6200 0    50   Input ~ 0
 PULSE-B
 Wire Wire Line
-	1300 6600 1500 6600
+	1550 6200 1750 6200
 $Comp
 L power:GND #PWR017
 U 1 1 602CD14A
-P 1900 7150
-F 0 "#PWR017" H 1900 6900 50  0001 C CNN
-F 1 "GND" H 1905 6977 50  0000 C CNN
-F 2 "" H 1900 7150 50  0001 C CNN
-F 3 "" H 1900 7150 50  0001 C CNN
-	1    1900 7150
+P 2150 6750
+F 0 "#PWR017" H 2150 6500 50  0001 C CNN
+F 1 "GND" H 2155 6577 50  0000 C CNN
+F 2 "" H 2150 6750 50  0001 C CNN
+F 3 "" H 2150 6750 50  0001 C CNN
+	1    2150 6750
 	1    0    0    -1  
 $EndComp
 $Comp
@@ -824,14 +824,11 @@ F 3 "" H 3650 7050 50  0001 C CNN
 	-1   0    0    1   
 $EndComp
 Wire Wire Line
-	1800 6600 1900 6600
-Connection ~ 1900 6600
+	2050 6200 2150 6200
 Wire Wire Line
-	1900 6600 2700 6600
+	2150 6200 2150 6300
 Wire Wire Line
-	1900 6600 1900 6700
-Wire Wire Line
-	1900 7000 1900 7150
+	2150 6600 2150 6750
 $Comp
 L Device:C C8
 U 1 1 6032AB87
@@ -962,24 +959,21 @@ Outputs
 $Comp
 L Device:R R13
 U 1 1 603B2486
-P 4900 5450
-F 0 "R13" H 4970 5496 50  0000 L CNN
-F 1 "4k7" H 4970 5405 50  0000 L CNN
-F 2 "" V 4830 5450 50  0001 C CNN
-F 3 "~" H 4900 5450 50  0001 C CNN
-	1    4900 5450
+P 4950 5450
+F 0 "R13" H 5020 5496 50  0000 L CNN
+F 1 "4k7" H 5020 5405 50  0000 L CNN
+F 2 "" V 4880 5450 50  0001 C CNN
+F 3 "~" H 4950 5450 50  0001 C CNN
+	1    4950 5450
 	1    0    0    -1  
 $EndComp
 Wire Wire Line
-	4600 5600 4900 5600
+	4600 5600 4950 5600
 Wire Wire Line
-	4600 5300 4900 5300
-Connection ~ 4900 5300
+	4950 5300 5150 5300
+Connection ~ 4950 5600
 Wire Wire Line
-	4900 5300 5150 5300
-Connection ~ 4900 5600
-Wire Wire Line
-	4900 5600 5450 5600
+	4950 5600 5450 5600
 Text Notes 7150 2350 0    50   ~ 0
 pulse\napprox. 200us\nlow 0 V
 Text Notes 10550 2350 0    50   ~ 0
@@ -995,14 +989,12 @@ NoConn ~ 2700 5800
 NoConn ~ 2700 5900
 NoConn ~ 2700 6000
 NoConn ~ 2700 6100
-NoConn ~ 2700 6200
 NoConn ~ 2700 6300
 NoConn ~ 2700 6400
 NoConn ~ 2700 6500
 NoConn ~ 2700 6700
 NoConn ~ 2700 6800
 NoConn ~ 4600 5200
-NoConn ~ 4600 5400
 NoConn ~ 4600 5500
 NoConn ~ 4600 5800
 NoConn ~ 4600 5900
@@ -1119,4 +1111,16 @@ Wire Wire Line
 	7750 5300 7750 5400
 Wire Wire Line
 	7500 5300 7750 5300
+Wire Wire Line
+	4800 5400 4600 5400
+Wire Wire Line
+	4800 5300 4800 5400
+Wire Wire Line
+	4950 5300 4800 5300
+Connection ~ 4950 5300
+NoConn ~ 4600 5300
+Wire Wire Line
+	2150 6200 2700 6200
+Connection ~ 2150 6200
+NoConn ~ 2700 6600
 $EndSCHEMATC
diff --git a/media/kicad-circuit-sketch.png b/media/kicad-circuit-sketch.png
index cd61ca0..7f11bb6 100644
Binary files a/media/kicad-circuit-sketch.png and b/media/kicad-circuit-sketch.png differ
diff --git a/src/main.cpp b/src/main.cpp
index e950eab..adb2174 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -7,12 +7,15 @@
 #include "GeigerData.h"
 
 // ~400µs high pulses from Geiger tube on GPIO 18
-#define PULSE_PIN 18
-#define PULSE_GPIO GPIO_NUM_18
+#define PULSE_PIN 15
+#define PULSE_GPIO GPIO_NUM_15
 
 // switch input for WiFi on (low) and off (high)
 #define WIFI_SWITCH_PIN 4
 
+// blinky LED
+#define BLINKY_LED_PIN 19
+
 // Keep 600 samples of 1s in history (10 minutes),
 // calculate radiation for russian STS-6 ("CTC-6") Geiger tube
 GeigerData geigerData(600, 1, STS6_CPM_PER_USPH);
@@ -58,7 +61,7 @@ void setup()
 	initDisplay();
 
 	// blinky
-	pinMode(LED_BUILTIN, OUTPUT);
+	pinMode(BLINKY_LED_PIN, OUTPUT);
 
 	// Geiger pulse input
 	pinMode(PULSE_PIN, INPUT);
@@ -79,7 +82,7 @@ void loop()
 {
 	// blinky
 
-	digitalWrite(LED_BUILTIN, blinky);
+	digitalWrite(BLINKY_LED_PIN, blinky);
 	blinky = !blinky;
 
 	// reset watchdog