Saturday, June 10, 2023

FNIRSI DSO-TC3 Component tester, Osilloscope and Signal generator

My (simple) component tester is very useful however it has some problems: It does not have a nice enclosure and is an open PCB powered with a 9 V battery on a cable and also the display screen is not fixed.

I could make my own enclosure however i looked on Aliexpress what are the other options. On Aliexpress the component tester is often called Transistor tester, however it can test many other components.

There are versions with enclosure and a rechargeable battery for around 18 euros, however i also found the FNIRSI DSO-TC3. This device does not only has the component tester, it also has e a one channel oscilloscope, a signal generator and some other tools onboard. Including shipping to the Netherlands it costs just above 50 Euros. 

Some days ago i ordered it and it came relative fast however some days later than the expected delivery day as mentioned on Aliexpress. I have played with it a few hours (and also used to test some of my components)
and am happy. On the internet you can find a description and several reviews of this device. I mainly used the component tester, The oscilloscope is single channel and has a limited bandwidth. The signal generator and the oscilloscope are nice for audio range frequencies. Unfortunately i could not find how to use them at the same time. Via the tools option you can also use a DHT11 temperature and humidity sensor or a DS18B20 temperature sensor.

The DS18B20 is a 1 Wire temperature sensor is a sensor that i already used in some projects and i have some in stock for further projects. It is very small and uses 3 connections ( +V GND and a 1 Wire data connection) It is possible to connect multiple sensors in parallel and get the temperature from each individual sensor as each sensors has a unique 64 bit serial code. Unfortunately on my DSO-TC3 i only see data of one sensor and the serial code of the sensor is not visible. It would have been a nice feature if at least this code would be visible so the DSO-TC3 could be used for identifying each sensor. If it was possible to read multiple DS18B20 on a bus it would have been even better. Perhaps this is something that in a new software version could be added? 

In summary the FNIRSI DSO-TC3 is for its price an interesting device. It is not possible to expect form that the same possibilities as from a much more expensive multichannel oscilloscope. Perhaps a firmware upgrade can even give additional features.  

Thursday, May 25, 2023

Niimbot D110

What is a Niimbot D110? It is nót a kind of robot. It is not related to a Nimbus 2000 from Harry Potters magical world. It is small, light, not to expensive and it can help in organizing things. It is a relative cheap thermal label printer. When i did see the price i knew this is not something to put my whish list and wait.  This is something i need to buy now especially as i am reorganizing my workshop.
However before placing the order i did watch several Youtube videos and i also installed the Niimbot app to test the software. 
One day after placing my order the playstore requested me to update the software and a short time later a second update for the app.. After this two updates i did try the software again and at that moment i had doubts if i was happy with my order. This as the software did not work anymore. I didn't know if this was due to the fact that i had no Niimbot connected or if the software had a bug. I could till cancel my order easy as it was not shipped yet, however i decided to wait. This as i probably would not be the only one with this problem and if the printer did not work at arrival i could return it anyway. The printer arrived relative fast and luckely another app update came before the printer arrived and it worked all fine.
The Niimbot D110, a small thermal label printer can only print black and the current price is just above 20 euro's including one label roll I think the low price if for two main reasons: 
1) Only Niimbot thermal labels can be used. The labels on the roll are not cut by the label printer and have fixed sizes. There are many different labels available, different sizes and also labels with colors and printed colored figures. 
2) The device itself has not much controls, only one switch with an led and you need to control it via a smartphone app using bluetooth. 
The app if free and in several app-stores. It contains a label editor and it is possible to print barcodes, QRcodes, using several fonts and font sizes, change direction or the content, and a use library with pictures and icons. You can also take pictures with your smartphone or use images to put on your label (no colors, only black). Importing a (small) Excel file to print a series of labels is also possible however i didn't try this yet.
More fonts and icons are in the payed VIP version of the app for a monthly. I found the VIP functionalities not sufficient interesting for its price and for normal use this is not needed.
When writing this review I already started labeling my inventory. The app to design the labels and the printer work very wel and i am happy with my Niimbot D110. I did buy a set that came with more rolls of labels. Also i did buy some transparent labels. (I did pay it for myself so this is not an advertorial or sponsored message!)
It is possible to buy labels in packs of 3 5 or 6 to get a better pice. I did not yet buy or tried other kind of labels. The label roll contains an RFID chip so the printer (and your app) knows which labels are currently in the printer. I already have an empty label roll and kept it to perhaps play with it using an RFID reader.
Changing labels is relative simple. However the first label after changing will probably not be alligned correct. Do not open the printer to fix this. The second label will be correct automatic. 
I will mention now some little things that could be improved / added to the app to make it even more usefull:
1) Exporting the print history is not possible. When you could export the print history e.g. to Excel you could get a complete list of your inventory after labeling. (You can import excel to make labels, however when inventarizing it is more easy to be on location, create a label on your phone, print it and stick it immediate on the item that to create a list in excel, print labels and match label per label with the item.)
2) Missing icons. There are several nice icons already in the app and een more in the payed VIP version.  However i do miss icons for standard hardware (diffent kind of bolts and nuts, flat/round top, to be used with normal, phillips screwdriver or special bits) that you can find in almost every home. Also icons for electronic components would be a nice addition. (Diodes, transistors, ICs, resistors, capacitors, leds etc.). I know the last set (electronic components) is perhaps somewhat specialistic. Standard hardware (nuts and bolts) is relative general. This would for me be more usefull than e.g. the icons for gardening.
It is possible to make this images yourself and use them with the printer, however i did not do this (yet). It would be nice if this where standard included icons. I did take some photo's of items to put it on a label. As far as i could see, even in the payed VIP version electronic of nuts and bolt icons are not available.

Friday, May 19, 2023

Inventory system part 2 – tools to use for NFC and QR

 As type NFC tag I selected round NTAG213 stickers. I experimented already with these tags. They have sufficient capacity for this applications, are easy to attach and also can be ordered easy (Aliexpress).

I have a lot of A4 printer labels 7cm x 2.5cm (3 columns 10 rows) and I wanted to use them also.

I like a relative big QR code and also a storage number written in digits. On small storage drawers a 7cm*2.5cm label is too big. So I decided to print text for two labels on one label and after printing cut the 7cm in 2x3.5cm. So in theory fit 6columns and 10 rows = 60 labels on one A4. Unfortunately I could not easy fill the complete A4 width. There missed a little piece of the QR code in the last column. So I decided to not use the last column and print 5 columns each 3.5 cm x 2.5 cm and discard the last 3.5 cm column. On small drawers I did put the label with the QR and number in readable format on the backside. At the front I want a small label with the content as text (and perhaps a small QR code).

It is possible to create QR codes that direct link to a webpage with the ID on the tag in the URL. However I decided not to do that and create a QR code that only gives the number.

To use NFC tags and QR code some tools are needed. I can build something to read and write NFC tags with a microcontroller like Arduino or ESP32. As my android smartphone as this is most times already available, using my phone is preferred.

For NFC tags several apps are available in the app-store(s). One app that draw my attentions and is Scan-it to office. With this app you can read an NFC tags, read a QR code, take a pictures, enter some text, and do several things more. The scan results can end up in a Google spreadsheet, a word or excel document, a database, a webform (using chrome browser) or are send to your (Windows or Apple) computer as if you entered the data using your keyboard. The free “demo” version that, at random intervals, does not send the captured data but a message. A paid version that doesn’t has this limitation costs (at the moment) less than 4 euros for one month for one smartphone. A three months or a year subscription gives discount and there is also a licence for use on multiple smartphones (e.g. for a company). A review and more details about Scan-it to office will be presented in a separate blog post. As already mentioned I will write on my blog also about some other NFC apps and what they can do.

To bulk print labels with QR code and a number, using my 7cm x 2.5cm (3 columns 10 rows) labels on A4 works good. Creating small labels describing the content of small drawers is a bit more difficult as you can only print a lot of labels at the same time, and after that you need to sort out on which drawer to put which label. There are now relative cheap small label printers available that can print directly from a smartphone app. I ordered one to check if this can help me with my inventory system.

So currently a lot of material that can be used for my blog posts even when I have not much time for real electronic projects. 

Tuesday, May 16, 2023

Inventory system part 1 - using NFC and QR (intro)

 I like #NFC / RFIDtags. ( RFID stands for Radio Frequency Identification, a contactless one-way communication method at varying distances. NFC, Near Field Communication, allows for two-way communication and  requires action by the user.)

You can read and write to NFC tags with a special reader/writer(/or clone) device, a NFC smartphone (most modern smartphones do have NFC) or using a microcontroller like ESP32 or Arduino using a cheap NFC interface. 

Especially the NTAG213 tags are very nice and are in bulk relative cheap available as stickers that can be used for labelling inventory.  The NTAG213 even has a built in counter that, in enabled, counts how many times you did scan the tag.  (For my last order in China of NTAG213 stickers I did pay EURO 11.83 for 100 pcs). 

Normal stickers with QC or bar code are cheaper. NFC stickers have the advantage that you can also write and modify information on it however labelling everything with NFC would be more expensive. 

When printing a QR or barcode you can at the same time print a numerical or text value for easy identification without using a device.

With a cheap NFC reader connected to an Arduino you can change the bytes on the NFC tag. However I also want to use my smartphone. I have some NFC apps on my smartphone. Reading or changing individual bits is not always possible with every android apps.

Therefore in one of my next blog posts I will describe some of the NFC apps on my phone with features and also some details about the NTAG213 .

Currently I am reorganizing all my electronics material due to a major change of my workshop. That is also the reason why i current publish less projects. However this is also the reason you will see some posts about topics related to this reorganizing. For my storage system there have some must haves and some wishes.

  • It needs to be a big improvement to the current situation
  • I want more standardization in my boxes (not a lot of different sized boxes with components that are difficult to stack…)
  • It must have an overview and searchable lists of components (in a computer system)
  • It needs to be extreme flexible and easy to adapt, maintain and correct
  • It may have (some) redundancy
  • I want to have more than just labels with some text my boxes. I like to experiment with things like NFC tags and QR codes for easy interfacing. However at the moment also OCR is relative good and can be uses.
  • It must be not too expensive

As I want it to be not too expensive it will not be possible to put NFC tags on everything. NFC are not extreme expensive however still cost more than 10 cents per tag and a QR code printed on a label is cheaper. Due to the kind, the amount and diversity of items I want to store the storage easy can become expensive compared to the price of the items.  However I want to use NFC tags on some items and put QR codes on every storage location (also on the locations where I did put an NFC tag.

On some drawers, boxes and more expensive items I did put a NFC tag and a QR code with an unique number. On small drawers and boxes for nuts, bolts and electronic components I did put only a QR code. The QR codes contains the number. In a follow-up post I will describe the numbering system I used. The NFC tag - number / QR code only indicate a storage location. The storage location is a “container” that can have  items inside. What is in a “container” can be indicated on a separate label on the “container”. A “container” (or “container” ID) is not a real indication where exactly an item is as e.g. the location of two component drawers may be swapped (intentionally or by accident). It is only an indication in which “container” the item is.

I want my storage system robust enough to handle swapping/changing the locations of “container”. So all my components will be inside unique numbered “containers”. A “container” can also be inside another “container”, sometimes together with other “containers” and other items. (E.g. a box can be in a drawer.) I hope this will give sufficient flexibility to store (and find) my components.

Monday, May 15, 2023

Mailbag may 2023

Time for a new mailbag blogpost (may2023). 
There are still some weeks in may left and i am expecting some more items. However after last mailbag post i received already several items and it is time to post a small selection.

Raspberry Pi extension to breadboard.
To get the Raspberry Pi GPIO connection pins easy to a breadboard

Raspberry Pi Extension hat.
To plug in multiple extensions to a Pi. At the moment i will use this only to connect the extension to the breadboard and at the same time the ventilator for the cooling of the Pi.
USB connectors.
The connectors i ordered only have wires for the power. There are also availables with wires on all ins.
Some cheap screwdrivers /  voltage testers.
I had an old one for many that was broken and repaired with tape. Now i ordered a set of 10 new. I did put them in different locations and some toolboxes (and did put some in stock). 
A small and cheap wifi camera.
Several different ICs/ chips for projects. (I did not put all pictures)
Privacy clips for smartphones / computers.
Easy temporary cover a camera lens for privacy.

Monday, January 30, 2023


PCBs to make ESP32 more breadboard friendly Including jumpers to select ground and power connections. 

To fit my ESP32 module nice on a breadboard i created this PCB.  When you stick this EPS32 module direct on a PCB there is no space to make connections. You can find several examples where users stick the module  on two PCBs. However wanted to keep the 'standard' PCB height and put it on only one breadboard. Therefore i created this PCB for my EPS32 module that can be plugged in the power lines of a breadboard.
To connect to the power rails of a breadboard solder some male pins pointing downwards in the top left, bottom left , top right and bottom right holes.

For the jumper connections it is best to solder in male Dupont pins. 

I soldered female Dupont connectors in the corresponding holes in the PCB for the module and the connections.
For the connections it is also possible to use male Dupont headers (or a combination of male and female). However the female version as it gives it a breadboard look. (I also build a version with 2 female one male row connection row. This is handy if you have sensors and buttons with female connectors.)

In the photo you see a version where i used male pins for some additional connections (GND,  3V3 and 5V) 

The PCB can also be used as 'stand alone' without a breadboard.  Mount the PCB using screws in the holes, the ESP module can easy be swapped or temporary removed for testing and reprogramming. 

Using jumpers power and ground connections can be configured.
(For the two power strips top row is always + bottom -)
The yellow lines indicate the connections.
Topright part of the PCB is the Ground configuration. The jumpers make it possible to connect GND1 GND2 GND3 GND4 to the top ground or to the bottom ground line.
Also bottom ground and top ground can be connected to each other.
On right bottom part of the PCB you find (vertical) some 3V3 points and Bottom ground connection points.
On left bottom part of the PCB you find (vertical) some 5V connection points.
Also on the left (bottom and top) there are 5V ans 3V3 points that can be connected to the breadboard top or bottom + power line.

The left and right power lines are always connected. You can use the PCB also to join to breadboards placed left and the right.

Below some pictures of the PCB design. 
( Red top copper layer, Blue bottom copper layer)

The PCBs where designed with EasyEDA and the project is there also shared.
Project homepage

Open in Editor,cmd_for_project=a2568d38d6634a1185e5220d4f53b901
PCB Top layer

PCB Bottom layer

The information, including the gerber files is also available on my Github 

Friday, January 6, 2023

How to get a Raspberry Pi 4 for free.

How to get a Raspberry Pi 4 for free in The Netherlands.
 I received a new Raspberry Pi 4 with help of the Dutch Government. Due to the chip shortage is is difficult to buy a new Raspberry Pi and also the prices age gone up a lot.
However i just received Raspberry Pi 4 sponsored by the Dutch Government. This together with a book, a breadboard and some components. And perhaps you can also get this. How is that possible?
{IMG of the Pi}

For many years in the Dutch Tax system you could get a tax deduction if you followed a job related study or training and spent more than a certain amount. However the tax rules did change some time ago. Now, in the Netherlands, you can apply each year for 1000 Euro's for a job related training using a 'Stap budget'. However this is a limited government budget and only a few moments per year when you can apply and the training needs to be on an approved list. When the application time is there you already need to be in the waiting list as the budget is quite limited. Also you need to finish the training otherwise you need to pay it yourself.. 

What has this to do with a free Raspberry Pi ?  There are many interesting training's available also several IT related, including a Raspberry Pi Programming (using Python) . When you have finished your training you get a certificate of attending and you can (/must) do an exam. Included with the training is a Raspberry Pi, a breadboard and some components. As the training costs less than 1000 Euro's you can get this training for free with the Dutch Stap budget mentioned above. So you will not only have a Raspberry Pi a breadboard and some components. You can learn something and get an certificate and diploma.

Be aware that the apply process is quite difficult. I used the time slot at 1 November 2022 at 10:00. Before that you need to register first for the course and get some information from the company that provides the training. A long time before my time-slot i already went to the registration page for the Stap budget. There you end up in a queue. (You can also go there on second device or with another browser to double your chance. ). At 10:00 i got a message that i was in a waiting list that would take more than an hour. 

Also several times i got a message that the waiting list was paused.

I did not need to worry and would keep my place in the queue. Finally after more than an hour an a half i got a message that the queue was around 60 minutes. and after that every minute the queue became a minute shorter. At around 12:30 (so more than 2 and a half hours) i could register.

A strange thing is that about 10 minutes after i was in the queue i decided to also go a second time in the queue (as mentioned above).  I could register using this second queue. In the first queue i opened my turn would be more than 50 minutes later than in the second queue. So there is also a lot of luck involved.

Due to the long waiting time I did think my chances where very low. If you do not get the Stap budget you do not need to follow the training or pay anything. After some days i got a first email that my application for the Stap budget was approved and a few weeks later a mail from my training provider.
Some time later i received a package from the training provider with the Pi and training information.
Within a year i need to finish the training.

Friday, November 25, 2022

RF Testboard

To experiment with RF and a VNA a clever designed test-board kit exists so i ordered one.

Below a description of the connections

RF testboard connections

Row A, F, G, B1 and B7 are all GND (In picture 2 presented as small circles)
Pad B4 C2 C6 E2 and E6 are Isolated (floating) pads (Not drawn in picture 2) 
The other connections between the pads are as drawn above.

Besides the PCB with the headers some jumpers and a 50 Ohm load is needed.
As a minimum it is recommended to make

2 pcs 2-pin short 
1 pcs  3 pin short
1 pcs  3 pin jumper
1 pcs 50 ohm load
Also having a 2-pin open as reference can be useful

The 50 Ohm load can be made by using 2 100 Ohm 0603 or 0805 SMD resistors in parallel (Stacked on each other). 

To make a through connection between the two SMA connectors place
2-pin shorting jumpers between D1-D2 and D6-D7 and a 3 pin jumper between D3-D5

A short or load (or open) can e.g. be made by placing appropriate components between E1 and F1

Below a picture of the kit that i did buy. It comes with the header pins and SMA connectors and 2 SMA resistors. 

I did solder the headers on the PCB and also the SMA connectors.
For the connections i first wanted to experiment with standard Dupont connectors and two "normal" 100 Ohm resistors. I know the quality would be better (and better usable at higher frequencies) if i would made it smaller, however i first wanted to get some experience and learn from the results.
I measured some of my resistors, trying to match 2 resistors to get close to 50 Ohm. However finally i just used two random selected resistors as, when measuring with my ohm meter, my 100 Ohm resistors all seemed to be just below 100 Ohm.
So i needed to use two of these resistors in parallel and the resistance would not be as close to 50 Ohm as i wanted. Using standard resistors on a normal Dupont headers would not be perfect for a 50 Ohm load anyway. To do first experiments at not to high frequencies it worked.