Summary

This add-on base is 100% compatible with the original LeHof Bat Signal. Simply snap the fixture into the new base. https://www.thingiverse.com/thing:259166
This base features four standoffs, allowing easy mounting of an Arduino Uno. You will need to drill a hole for your photocell to poke out a bit- determine this on your own, as your photocell may not be placed exactly like mine.

Coding/Wiring Bat Signal Night Light

NightLight Code

            <div><p>/<em><br>Test out the desired threshold of your photocell using the serial monitor.<br>This setup should turn on the batSignalPin in complete darkness.<br>The photocell may pickup some light from the Bat Signal itself. Setting the else if photocellVal a bit higher will account for this, keeping the light from turning off due to its own intensity.<br>My setup uses a 10k resistor on the photocell.<br></em>/</p><p>int photocellPin = 0;// Photocell connected to analog pin 0<br>int photocellVal = 0; // define photocell variable<br>int batSignalPin = 11; //define LED connected to pin 11</p><p>void setup() {<br>Serial.begin(9600);<br>pinMode(photocellPin, INPUT);<br>pinMode(batSignalPin, OUTPUT);<br>}</p><p>void loop() {<br>photocellVal = analogRead(photocellPin);// read the analog from photocell<br>Serial.println( photocellVal); // output to screen</p><p>if (photocellVal &lt; 100){<br>Serial.println("Bat Signal ON");// Output to Monitor<br>digitalWrite(batSignalPin, HIGH);<br>}                      </p><p>else if (photocellVal &gt; 400){<br>Serial.println("Bat Signal OFF");// Output to Monitor<br>digitalWrite(batSignalPin, LOW);<br>} </p><p>delay(1000);</p><p>}</p></div>                <p class="detail-image"><img src="https://cdn.thingiverse.com/assets/0a/81/d0/26/ac/PhotocellWiring.PNG"></p>            <p class="detail-caption"><strong>Diagram courtesy of Lady Ada of Adafruit.com</strong></p>

LeHof's Bat Signal Arduino Uno Base Extension