Intro: Light Up Halloween
Using Infrared Diodes to light up your people when you get close to them. When your transmitter lights up their Detector their lights light up and their Transmitter lights up you. When someone touches your magic spot(your detector) your spot lights up and their thing lights up. It is simple and easy to do with Transistors. Transistors rule our world. I will show you how to light up your people with transistors.
First thing you need is parts. Soldering is the best way to make things you can play with. Radio Shack still sells transistor packs in PNP and NPN. PNP Amplifying Transistors (15-Pack) part # 276-1604. RadioShack NPN Transistors (15-Pack) part # 276-1617.Usually about four types of each. I am using PNP transistors in this circuit. You can use any of the types of PNP transistors in this pack. Either the 2907 or 3906 work well here. I ran out of 2907 transistors. The next part you need is a good Infrared Emitter and Detectors pair. Meaning they have the same Wave Length in Nano-Meters.
Infrared 880 Emitter and Detector Pair. Out of all the parts I have the ones that worked are the best ones for this circuit. They are the little side shooter two lead type. The Transmitter is the Emitter Diode 880nm. The Detector is the Photo Diode or Photo Transistor or Photo Darlington in 880nm. Jameco.com is the best place to get all of the parts. I included the PDFs. Use the term ‘Infrared’ to search in Jameco.com. You only need enough power to cross about two inches. All infrared works best in the dark. Most ranges 800 to 1050nm will work together.
Jameco.com has packs like RESISTOR, 610 PACK E12-SERIES 1/4W 5% TOLERANCE part # 2131039 and hook up wire 10 Color Stranded Wire Kit Assortment part # 2130917. 1900 Leds T1 AND T3/4 ASSORTED COLORS AND SHAPES LED GRAB BAG part # 135271($99). For a good soldering station I have the makezine.com/store Variable Temperature Soldering Station - 5-40 watt part # MKPE1 under tools. Also if you do more types of crafts a wood burning kit that has a soldering tip and hot knife may a better tool to have. I can’t live without my mini toothed priers, min sharp diagonal cutters, my standard aluminum body X-Acto knife and my mini hot glue gun.
The circuit is simple. When the Detector gets hit by a Transmitter its resistance lowers. This brings the Base of the PNP transistor more negative and it turns ON and your lights light up. The 10K resistor to V+ to the base of the PNP transistor biases the transistor OFF. The transmitter can have its own battery and a switch. They use the most current when they are On. When you are near to your people switch your transmitter on. I made this with a 9 volt circuit so it is easy to make and have fun with. For masks, toy swords and shields mount your Leds any way that suits you. Put the Transmitter on top or right and the Detector on the bottom or left. See pictures. The Transmitter can be another circuit and battery. Turn it off when you are not around your people. Leds can be put in a ladder Each with its Resistor to the V+ rail and negative to the Ground rail.
Because of the 9 volts use a 330 - 470 Resistor on your transmitter. Infrared diodes come in different power outputs. See how close you have to be to turn on your lights on and adjust the resistor’s value. Resistor are in Ohms. 470 is 470 Ohms. 1K is 1000 Ohms. 10K is 10000 Ohms. You may notice that I have no resistors on my Leds. Leds are Diodes. Diodes in series take their Current Each up to your supply voltage. Diodes have a Forward Voltage measured with a Digital Volt Meter set on Diode. Red Leds have the lowest and Yellow and Blue have the highest Forward Voltage. The size and power of the Led will determine its Forward Voltage. Measure them and add up your Leds to see how many you can put in series with your supply voltage. I can get 5 Leds with Red Leds on 9 volts. Leds need about 2 volts to operate. One too many Leds and the lights go out.
In the A & B circuits the lights turn on when the Detector is hit by a transmitter. In the C & D circuits the lights turn off when the Detector is hit by a transmitter. In the B & C circuits the transmitter is powered by the transistor when the Detector is hit by a transmitter. All of the transmitters have switches. I did not have friends to build this for. I should have done more work on the C & D circuits before I uploaded the article. It is a very simple circuit. I found errors in the ten copy PDFs and I replaced all of them. Sorry I pushed Fritzing too hard.
Making the Boards is easy. Positive Resist Boards, Positive Developer, Etchant and Exposer Lights are available at Jameco.com. Print the PDF files at 100%. For laser printers print transparency sheets on the smooth side. Ink-jet on the rough side. I did not have friends to build this for. You can cut PCBs with a light duty metal sheet cutter. Etching. Etching solution is Ammonium Persulphate at 250 grams to 1 liter of water. 125 grams 15 ounces water. Keep etchant warm. Developer is Positive Type P.C. 1 part to 10 parts water. 1.5 ounces to 15 ounces water. Use plastic trays and bottles. The switch I found on Jameco.com SPDT PC mount standard is 3mm spacing and my board is .1in. Drill the lower two holes 5/34 and the first hole a little bigger .039. Use .035 most holes and .037 for a little bigger.
Working with Fitzing.com. You need Electronics knowledge and Desk Top Publishing experience. An example is the Object Label used in all views. Right click the Object select show label. Select the Object and Left click the Label and drag it. Right click Label select edit, size, rotation and Display Details.
You must get the BreadBoard and the Schematic Perfect before you can get a good PCB. No Birdcage Wires anywhere. Test all circuit paths by clicking on a node. Then in the PCB remove any Birdcage wires, rotate and move the parts and delete and make new circuit paths. After it looks OK then use Auto Routing. You make big changes in the BreadBoard first then the Schematic if you need it and then the PCB.
Making multiple circuits on one PCB. Save your project as somethingA10. In PCB view click the PCB and in Parts set Sticky to unchecked. Click and drag the PCB away from your circuit. Set your PCB to the size that you need. 4x6 is width 101.6 and Height is 152.4mm. Drag a selection box around your circuit. Let go. Edit Duplicate the circuit(Ctl-d). Wait for it to show up. Do not click it. Use the arrow keys to move your duplicate onto your PCB. Repeat this for each copy. The BreadBoard and Schematic will be a mess. Line things up nicely. Save your project. Make an editable PDF. Wait for it. Done. I do not put Sticky back on. Watch out for Duplicate errors when making multiplying copies in one PCB of the same circuit. Look at the labels they are label plus copy number. Do not touch the BreadBoard or the Schematic.