Wednesday, July 24, 2019

RGB led for experiments

For easy experimenting added resistors and a Dupont connector to a 'normal through hole' RGB led. Transparent heat shrink was added for electrical insulation and to keep the resistors (and the common pin wire) visible.

Friday, July 19, 2019

iTag Bluetooth tracker

Bluetooth iTags advertisements say you can use this cheap devices to find your keys, wallet and other items.
I ordered 5 of this iTags to see if they can really help me and my family to find items or prevent losing them. On the Aliexpress page i found 4 different colors so i received two of the same color.
The iTags came in a plastic bag with a small instruction on paper with QR code links to the software without the CR2032 Lithium (3V) battery. From the 5 iTags i received one did not work.
The cover of the battery compartment needs to be removed to put in the new battery. It is not mentioned in the manual but you can easy swap two covers with different colors. This way you can easy identify more than 4 distinct iTags without writing on it.  You can make combinations like a Black iTag with a White battery cover.
iTag with battery cover
of iTag of another color
The QR code for English android software links to the cTracing app on the Google Play Store. With this app you can use multiple iTags. In the app you can change the name of the iTag and even add a photo to identify the iTag.
Keeping the push button on the iTag pressed 3 seconds sends outs two beeps on the iTag, a led on the iTag starts flashing and the iTag is switched on and can be connected to your phone using the app.
If the distance between the iTag an the phone is to big (and the Bluetooth signal gets weaker) an alarm can go off. In the app the distance can be set to short, medium and long. Also the distance unit can be switched between meters and foot. Depending on the settings the button on the iTag can also be used to activate an alarm on the Bluetooth connected phone, switch on voice recording, take a photo or store the current location.
It also should store current the location if connection between the tag and the phone is lost. To find lost items with the iTag and the app, or use the app for preventing loss of your items will be very challenging. The Bluetooth on the iTag can switch of after a few minutes. The connection will be lost and a false alarm will be triggered. Also finding your iTag back after leaving it somewhere a few hours will be quite impossible as the iTag will be switched off and not sending a traceable Bluetooth signal.
To use an iTag to find your phone also does not work as the connection between the iTag an the phone is not (always) restored automatic if it was disconnected and the Bluetooth signal is received again by the phone. Perhaps other apps (or another phone setting) will help to overcome this problem.
Also i noticed some small differences between similar looking iTags. I have seen photo's and video's where you can only see two battery connections and a white plastic when opening the battery compartment. In my iTags can see the PCB with some connections.
Besides the color there are also some other small visual differences between the iTags i got from my seller. Some have a small battery connections at the side and others have a somewhat bigger connection at the side to the +pole of the battery.
I don't know if there are other differences (e.g. in the internal hardware or software) of iTags that look similar.

The iTag i received switches off automatic and triggers false lost signals. Also one of the 5 cheap iTags was dead on arrival. Perhaps there are better iTags but due to this issue i can not recommend this iTag and i doubt if it can really help you find lost items.

More info
JG iTag Alarm

The £1 Bluetooth Tracker

Tuesday, July 16, 2019

SMD project

To get more experience with SMD soldering i build this led chaser.
The circuit of this running light consists of a 555 timer to make pulses
 and a 4017 counter. Both ICs are SMD and also the two condensators C1 and C2 and the other 12 resistors.
The photo below shows the difference is size of a "standard" resistor and an SMD are also small SMD leds, however "standard" red led lights are used.
To my surprise the SMD intergrated circuits where more easy to solder than the resistors and condensators.
I used a soldering iron, flux pen, tweezers and a magnifier glass.
The video shows the working circuit. As you can see the  wires of the leds are not cut off as i wanted to attach Dupont connectors to do some more experiments with this small cheap Aliexpress DIY circuit.