Thursday, March 26, 2015

Cutting the ledstrip

So I bought myself several rgb-ledstrips at the dollar-store (Action) when they had a sale. The strips are 5 meter long on a reel and delivered complete with steering electronics and an infrared remote control. For 16 euro a real bargain. Like I said I bought several and one of them is in my living room at the top of a large bookcase. It was constantly sliding of the bookcase and therefore I designed a ledstripholder with my 3d printer as discussed here.

However that is not what this blog entry is about. I want to use the ledstrip in an infinity mirror. But 5 meter is way to long. So I have to cut part of, it. I really had to test that.

So let us take a closer look.

The ledstrip ended in a black cap.

I was afraid there would be end-resistors or something like that beneath that cap. So I carefully removed it and it then revealed just some contacts nothing more, pfew. 

Now lets look at the strip itself,

As you can see the strip is divided in parts. Each part contains 3 leds, the big white squares. But there is more. Each part contains its own limiting resistors, the small silver dots. So you do not have to take care of that and just supply some power. The strips are connected by copper contacts. And as you can see the RGB leds are common anode types as there is one +12volt lead.

So I took some scissors and cut at the end of the strip one section off.

Now first things first. Test if the remaining part still works.....

So far so good. Now for the testing of the cut off part. I started, using a sharp knife, by scraping of the plastic until the copper contacts were accessible.


Then I attached a 12 volt power supply and.......... nothing happened. So I think I must have cut some wires when cutting away the plastic. So I cut off a new part and this time removed the plastic by melting it with my soldering iron.

Next step is to solder some wires to the contacts and put them into a breadboard. Last week I showed you how to make your own breadboard wires. You can find that article here. That is something that came very helpfull here. 

So now there was only one thing to do: test.

Yep. It works.

For testing I put 12 volts to the lead that marked 12 volts and ground to the other leads. In this picture I just connected one of the RGB leads. The leds are very bright as you can see.

Oh and do not be afraid that you reverse the power, they are leds after all.....

So the lesson learned this time is not to cut away the plastic but melt it away with your soldering iron.

Next stop: steering the strip with power transistors. The end goal is to control the ledstrip with an Attiny or Arduino. The Attiny would be sufficient as it has 5 pins and we need only 3.

Till next time. Have fun.

Friday, March 20, 2015

Bluetooth module

So I ordered and received a bluetooth module. It is the famous HC06 module. This module is capable of connecting your Arduino to an Android phone-tablet or whatever !! Home automation gets in reach. If you order one make sure it is the HC06 that is put on a base plate.

The green PCB is the actual HC06. The blue PCB beneath it is the baseplate.

The module being on a baseplate has some distinct advantages. First there are breadboard headers mounted which makes it easy for experimenting. Second the HC06 is actually intended to work on 3.3 volts. The version on the baseplate heowever also works on 5 volts. That makes my life a lot easier.

Lets have a look at the backside:

As you can see the module on the baseplate is suitable for a voltage level of 3.3V to 6 Volts. Ideal for working with my standard Arduino and Attiny85.

Wait a minute. Yes I intentionally mentioned that this will work with an Attiny85.

In the Arduino software you will need to include the SoftwareSerial library which is standard supplied with the Arduino IDE. For an Arduino Uno and an Arduino Nano you just have to attach the HC06 TX pin to the RX pin of the Arduino and the RX pin to the TX pin of the arduino. These are normally pin 0 and 1. Makes sense doesn't it. The processor is transmitting so the HC06 has to receive and then other way round.

When using this module with an Attiny85 SoftwareSerial allows you to use any pin of this micro for the communiaction. It is set with the following commands:

#include <SoftwareSerial.h> //Software Serial Port
#define TxD 0 //pin 5 from Attiny85 to pin RXD of the bluetooth module
#define RxD 1 //pin 6 from Attiny85 to pin TXD of the bluetooth module

SoftwareSerial blueToothSerial(RxD,TxD);

As you can see we normally use the same pins for the communication as on the larger Arduino versions to make life easy

On the front side of the HC06 there is a red led which will blink as long as there is no connection between the HC06 and another bluetooth device. As soon as there is a connection the led will be on. As soon as connection is lost it will blink again.

When pairing with another bluetooth device the HC06 will be the slave unit. So your Android phone or tablet will be the masterunit. When they first make contact the HC06 will ask you to enter its password. That way you can be sure communication will only be allowed between these two units. The standard password for the HC06 is 1234.

If you follow this blog maybe you want to order one of these. They are fun to play with and I have several small and large projects coming up using this module. First step is to control a relay with an Attiny85. Next step is to do that with your Android Phone.

Till then have fun.

Sunday, March 15, 2015

Cutting up designs in Tinkercad 

In my story about making a slide scanner/digitiser from your Android Phone using a 3D printer I mentioned that the design I made in Tinkercad was to big for my 3D printer.

So I had to cut it up in two parts to have it fit on my printers bed. But how do you accurately cut a design up.

Well the video below shows it.

Tuesday, March 3, 2015

DIY Breadboard cables

I am doing several experiments for projects I am working on. I guess everybody does that. I was working at a small project in which I wanted command a ledstrip with an Attiny85. So I soldered wires to the ledstrip. But then I needed to connect them to my breadboard.

I thought it was a waste of material to cut a real breadboard cable and solder it to the ledstrip. Instead I decided to make my own breadboard cables. I'll show you how.

What you need are plane simple paperclips. Take the small ones as the wire of the big ones is to thick.

Now first use a pair of plyers to straighten the paperclip

Next cut the straightened thread into 4 equal parts.

Now solder your wires to the parts

And that's it. ready for the breadboard.

Till next time.
Have fun.