Maker-First Steps in Electronics-Light guided rotating and moving plastic container

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Light guided rotating and moving plastic container

In previous Maker tutorials WE were using LEDs and vibration motors, WE will continue with it and adding some NEW components: a transistor and a LDR (Light-Dependent Resistor). WE will use ALSO AGAIN a plastic container, this time a transparent one so that persons could see WHAT’S inside (for the curious ones) 😉 This will ALSO push the makers WHO are building this project to work neatly as everyone could see the quality of THEIR work!!

Thus said, let me tell YOU that I first tried to fix the battery holder and the switch with instant glue; it didn’t work well!!

Example with instant glue to fix the battery holder and the switch: BAD solution as the glue reacts with the plastic and makes a BAD looking, NOR are they real well fixed on the plastic!!

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BETTER solution is to fix (solder) the battery holder and the switch on a small part of stripboard and to make the connection to the main stripboard (where all the components are) through a flat cable. Therefore we need to drill some holes with a 1 mm drill exactly there where the pins of the switch and the battery holder are. Now measure the length of the stripboard and once the holes are drilled, place the switch and the battery holder and solder them on the stripboard.

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NEW components are used in this project as a transistor, an LDR and a trimmer (adjustable resistor)

WE are using a transistor is this project; a transistor is a semiconductor who basically works as a switch or an amplifier. WE will NOT GO to much into theory, YOU can discover more in the “Learn more section below”.

START Text from http://www.build-electronic-circuits.com/ldr-circuit-diagram/

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Light dependent resistor or photoresistor is a device whose resistance is dependent on the strength of the light as they are composed of high resistance semiconductor material. When light hits the device, the photons give electrons energy. Higher the power of light, lower the strength of resistance. This particular action makes the electron jump into the conductive band and thus conduct electricity. Taking a cue from this concept, Øyvind Nydal Dahl, in this tutorial, has dealt in a circuit for LDR or Light Dependent Resistor to make a light detector.

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The above LDR Circuit Diagram works on the amount of light penetration. Hence, when it is completely dark, the LDR occupies high resistance. As a result, the voltage at the base of the transistor becomes too low to turn the transistor ON. At this stage, the current doesn’t flow from the collector to the emitter of the transistor, instead, it passes through the LDR and the potentiometer.

When the light is provided at comparatively low density, the LDR has low resistance. But it is sufficient enough to bring the voltage at the base of the transistor higher and also to turn the transistor ON. Once the transistor is turned on, current starts flowing through it from the positive battery terminal to the negative battery terminal covering R1 and the LED (IN OUR CASE, through the vibration motor). With this, the LED, lights up (IN OUR CASE, the motors go on vibration). [END Text from http://www.build-electronic-circuits.com/ldr-circuit-diagram/]

WE use the same schema as in above tutorial, BUT WE replace the LED by two (2) vibration motors. Check the schematics below, please.

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Learn more:

• Transistors
• LDR (Light-Dependent Resistor)
• Trimmer (Adjustable resistor)
• …

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The schematics of our project

Here below the schematics where YOU will see how the components are represented; ONLY eight (8) parts. The two vibration motors are in parallel.

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Check this layout please to find out how to connect the transistor.

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Learn more:

• Datasheet BD137

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The components

Please find below the components:

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For the details, please check below.

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Detailed parts list, supplier and prices

Please find below the detailed parts list as well as the supplier and the prices.

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Item and quantity	Supplier and order number	Price
A bit flat cable, silver wire and 1 x drinking straw	CONRAD: 604069-62	0,50€
1 x LDR (Light Depending Resistor)	CONRAD: 140374-62	2,59€
A bit heat shrinking tube		0,50€
1 x Switch	ADAFRUIT: ID 805	0,95€
1 x Battery CR2430	CONRAD: 612987-62	3,99€
2 x Vibrating Motors from Adafruit	ADAFRUIT: ID 1201 à 1,95€	3,90 €
1 x 5mm flashing LEDs from Adafruit pack of 10 is $4.95	ADAFRUIT: ID 680	0,50 €
1 x Battery holder	CONRAD: 65058-62	1,15€
1x Trimmer (variable resistor) 100k	CONRAD: 423858-62	2,69€
1 x Transistor BD137-16	CONRAD: 151036-62	0,23€
Total:		17€

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As you can see it is a very cheap project, ONLY 17 € and easy to realize! ALL what YOU need is a bit time, passion and here we GO! 😉 Have FUN!

Online ordering links:

• Adafruit
• Conrad
• …

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I used the upper cup of a yogurt (0,89€) which is transparent and BTW is delicious 😉.

 

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The tools needed

Check below please WHAT the tools are that you will need for this project. The small saw is needed to cut the stripboard.

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WE need also a mini drill to drill the wholes for the switch, the battery holder and the whole for adjusting the variable trimmer resistor.

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Details of the LED in the drinking straw

WE are using a multi color LED from ADAFRUIT (ID 680), a Diffused 5mm Fast Flashing RGB LED, which works with a voltage of 3 Volts; so we don’t need any resistor in series. To make a neatly connection we will use a flat cable and to avoid a shortcut we will fix our soldering with heat shrinking tube. Please follow the steps below.

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The LED will get soldered on the Plus and Minus of the second stripboard; it will flash permanently as far as the switch is on “ON position”.

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Learn more:

• LED (Light-emitting diodes)
• …

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Practical Tip: LEDs are transparent, so the Cathode (Minus) looks always a bit larger as the Anode (Plus).

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The MAIN stripboard with the components

Below YOU can see the work in progress.

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In above photo you can see the soldering on the stripboard as well as the fixing with hot glue on the bottom.

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Some adjustments are needed

Do YOU remember that WE drilled a hole just in the height of the axis of the trimmer (adjustable resistor)? Check photo below, please.

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For this WE will need a 1 mm screwdriver and a torch. I used a mini LED torch from CONRAD (Item no.: 868885-62 for 6,99€).

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How-To make the adjustments: put the light source in front of the LDR and trim with the 1 mm screwdriver until the motors are vibrating, if the motors are already vibrating trim back (turn the reverse direction…). This might take some time until you got it to the right point; the motors should only vibrate WHEN the light source is on!!

 

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The video of our project

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Check out this video, which explains very well how it works.

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L’auteur Gust MEES est Formateur andragogique / pédagogique TIC, membre du “Comité Conseil” de “Luxembourg Safer Internet” (LuSI), appelé maintenant BEESECURE, partenaire officiel (consultant) du Ministère de l’éducation au Luxembourg du projet  ”MySecureIT“, partenaire officiel du Ministère du Commerce au Luxembourg du projet ”CASES” (Cyberworld Awareness and Security Enhancement Structure). L’auteur était aussi gagnant d’un concours en électronique en 1979 ( Pays germaniques ) et voyait son projet publié dans le magazine électronique “ELO”. The author Gust MEES is ICT Course Instructor, ”Member of the Advisory Board” from “Luxembourg Safer Internet” (LuSI), BEESECURE, Official Partner (Consultant) from the Ministry of Education in Luxembourg, project “MySecureIT“, Official Partner from the Ministry of Commerce in Luxembourg, project “CASES” (Cyberworld Awareness and Security Enhancement Structure). The author was also a winner of an electronics contest (Germanic countries) in 1979 and got his project published in the “Electronics Magazine ELO”).

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Stay tuned for next blog post(s) 😉

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Keywords necessary for me to create this blog post: LDR, Light Depending resistor, resistors, vibrating motors, LEDs, transparent plastic container (yogurt), strip board, flat cable, drinking straw, drilling, adjustable resistor, trimmer, transistor, drilling, hot glue,

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