tag:blogger.com,1999:blog-83929591801348670282026-02-16T12:31:03.079+01:00To share random thoughts and projects on a wide range of topics like microcontrollers, iot, amateur radio & medical technology Unknownnoreply@blogger.comBlogger76125tag:blogger.com,1999:blog-8392959180134867028.post-51274811200237840702024-12-08T22:18:00.003+01:002024-12-08T22:41:56.941+01:00

For most cases of random number generation, systems use a pseudo-random number generator (PRNG), that is an algorithm that generates numbers that "look" random. But for certain applications, where true randomness is required — as in cryptography or simulations — there’s a different approach: draw on a physical process that, by its nature, is unpredictable. Radioactive decay is one such process

Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-8392959180134867028.post-21155906967432075502020-04-24T14:34:00.002+02:002024-08-01T13:24:37.908+02:00

Most of us will have a couple of old infrared remote controllers lying around. Often we need to use several remote controllers and complicated sequences of key presses to get a specific channel on a TV set which is connected to a cable box. Those old remote controls uses Infrared light to control the equipment Wave forms which drives an infrared led inside a remote control. The top trace is

Unknownnoreply@blogger.com3tag:blogger.com,1999:blog-8392959180134867028.post-14704542627490104322019-05-05T15:23:00.003+02:002019-09-18T20:37:01.202+02:00

Si5351 is an integrated circuit from Silicon lab for generating a custom clock signal and is very popular among the amateur radio community. It makes the job of building a vfo a lot simpler. A tiny sdr prototype based on FST3253 mixer  driven by a quadrature signal from Si5351 and controlled by  Attiny13 Setting up the correct values in the devices registers are needed to output a

Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-8392959180134867028.post-12340300412046133742019-01-14T16:38:00.000+01:002019-02-25T13:22:25.066+01:00

Here is a simple project based on Attiny13a ( which is limited with 1kb flash and 64bytes of SRAM). In this project a simple sensor node is made out of this and collects data from a digital temperature sensor (ds18b20)  and the ambient light with an ldr and converted by the ADC(analogue to digital converter) inside the attiny13a. Wireless sensor in a transparent  tic -tac box to

Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-8392959180134867028.post-62756309430144374532018-11-28T10:54:00.000+01:002018-11-28T11:14:02.868+01:00

Recently i got hold of a TFT  lcd module which is listed as "2.0" 3.3V TFT LCD Display Touch Screen With Touch Pen Breakout Board For Arduino" in ebay and  Aliexpress. They are very inexpensive for hobby projects. They use an 8 bit parallel interface to communicate and needs 13+ gpio pins for proper operation. Pretty good for small and shiny user interfaces as they also have a resistive

Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-8392959180134867028.post-59953876746103825762018-07-27T12:51:00.002+02:002018-07-27T13:01:19.674+02:00

In this project we are going to dig the details of a floor heating controller with wireless thermostats from LK systems.  The idea is to learn more about basics of AVR microcontrollers WARNING: In this case, the original device is decommissioned and using a modified firmware in a device which is in use is not recommended. The author is not liable for the potential harm from such an

Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-8392959180134867028.post-17175941143315055742017-04-10T10:57:00.001+02:002019-04-12T10:04:00.451+02:00

Here is a log of my experience in building and boxing a  simple VSWR analyzer. The idea is to make it small, and confined to a box (so that the components are saved from my frequent tinkering and impulses) and to cram maximum things in a small box. If you want to build immediately, please go to my completed (old) project with source here . This one is still going on and at an

Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-8392959180134867028.post-69626670509116653862017-02-02T15:28:00.003+01:002019-10-07T09:44:09.363+02:00

When we need more processing power and better performance with lower power usage, often we need to move to better and more powerful microcontrollers. I was using AVR and Arduino platform for most of the projects as they do not need much processing requirements. But for doing signal processing, real-time audio /video etc we need to use faster processors. In this post am trying to summarize my

Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-8392959180134867028.post-72742354029975186332017-01-19T13:35:00.000+01:002017-02-16T10:48:51.644+01:00

Here is a simple tool to convert bitmap images of 84 pixel wide and 48 pixel height to hex codes for using with arduino's and in other avr projects (may work on other images as well, but no guarantee). Graphic LCD with PCD8544 controllers (esp Nokia lcd, 3310, 5110 etc should work) If looking for creating hex and bin matrix for ordinary led matrix using click, the tool can be accessed at the

Unknownnoreply@blogger.com3tag:blogger.com,1999:blog-8392959180134867028.post-12679308673497372122017-01-08T18:49:00.000+01:002017-05-12T15:49:53.931+02:00

Printed Circuit Board (PCB) forms the foundation for many electronic projects and making a PCB at home is one of the useful skills to develop. If you think about the time and the headaches associated with home brewing a PCB, there are several cost effective solution which provides very nice boards at the cost of a long waiting time (for the postage). DirtyPCB and oshpark are some useful ones.

Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-8392959180134867028.post-77959137339071692152016-12-25T12:35:00.000+01:002017-05-12T15:51:32.571+02:00

ESP8266 is an extremely popular module among hobbyists for building inexpensive and powerful internet connected projects. The module can connect to a wifi access point and can exchange data. It can act as a wifi access point and can be used to control devices. The GPIO pins on the module can be used for automation and much more (SPI, I2C, I2S). This post is a log of my quick and dirty test

Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-8392959180134867028.post-40084124321342248192016-12-11T17:10:00.000+01:002018-02-03T13:56:21.159+01:00

Si5351 vfo cum bfo with S meter for hombrew trx Here is a Simple vfo+bfo using Si5351 and a 16X2 lcd with an S-meter. It is based on atmega328 as a controller. The connections for LCD, Si5351 and AVR are explained in may previous post at "A Simple Si5351 based vfo (signal generator) for ham radio use [quick start-setting up and general details]"  The idea is to keep it very basic

Unknownnoreply@blogger.com15tag:blogger.com,1999:blog-8392959180134867028.post-82648183258364722312016-11-05T14:23:00.003+01:002017-01-05T09:37:12.967+01:00

A simple and stable vfo is an integral part for radio experiments. There are several solutions to generate an rf signal ( Popular ones are : ad9850 dds, Si570 ) for amateure use. Recently the clock generator chip (Si5351A) from Silab is gaining popularity due to its lower cost and ability to generate multiple clock signals (For e.g it can be used as bfo and vfo at the same time) In this

Unknownnoreply@blogger.com8tag:blogger.com,1999:blog-8392959180134867028.post-9713799056560625802016-10-16T15:27:00.000+02:002016-11-05T14:55:11.991+01:00

Variable capacitor for a simple loop antenna for receiving A variable capacitor is useful in various projects like magnetic loop antennae, crystal radio and in making antenna tuners. It is often necessary to know the range (max and minimum pf value) of the capacitor for designing its application and to choose optimal coils for covering the suitable area of the rf spectrum. The solution is a

Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-8392959180134867028.post-17679914208190652252016-09-21T18:32:00.005+02:002016-11-05T14:55:38.228+01:00

This is a very simple tutorial article for those who want to start using an infrared remote with an arduino for controlling different things. This will cover the basic principles and can be used to perform complicated things as in my previous posts here and here Things needed 1) An arduino uno or compatible boards (atmega328 based) 2) IR Receiver Module 38 kHz TSOP4838  (

Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-8392959180134867028.post-57074749561410596862016-09-18T16:04:00.003+02:002016-11-05T14:56:03.157+01:00

When you need to move something with your micro-controllers (or arduinos), Stepper motors comes to your rescue. One of the cheapest and widely used stepper motor is 28BYJ-48 which can work with a 5v supply and gives enough juice for small tasks like moving a small robot or a small lever or a valve. Quick start with a 28BYJ-48 with an arduino Quickly test the Stepper motor with an arduino

Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-8392959180134867028.post-21891870339975103762016-07-20T19:00:00.002+02:002016-12-10T13:26:29.729+01:00

See code on a character lcd  as it is being sent! Quick iambic practice keyer with arduino uno and a lcd shield I like cw a lot and was using a straight key for most of the time. As the wrist is getting bad, started moving to automated keyers and a iambic one looks very attractive and is available in most of the transceivers. So here is a post which can be hooked up in a couple of

Unknownnoreply@blogger.com15tag:blogger.com,1999:blog-8392959180134867028.post-37658189962498879072016-07-06T12:15:00.000+02:002018-05-14T13:58:56.183+02:00

I recently came across a small board with stm32f407vg with all necessary components to use in DIY projects. In this post i would like to share some of the details esp , the pin connections which will be useful for others.  I found this board useful in some of my SDR (software defined radio ) projects and some audio projects (using DSP) This board is shown in the figure below and can be

Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-8392959180134867028.post-30728154553437919102015-12-24T14:25:00.001+01:002016-01-05T14:20:35.929+01:00

DDS with Rotary encoder and ili9341tft Rotary encoder is a handy add-on for most of the arduino projects which will serve as a measurement instruments, signal generator, direct digital synthesis (dds) vfo and several other projects.  Adding an encoder to your project is pretty easy. In this post i will take in to it quickly. This tutorial is based on a simple and inexpensive encoder with

Unknownnoreply@blogger.com6tag:blogger.com,1999:blog-8392959180134867028.post-2358422426104931382015-10-25T16:01:00.003+01:002019-04-04T14:17:32.191+02:00

Sweeping a 14.318 crystal on the dds sweeper After finishing with a simple vswr plotter using an arduino pro mini and a tft, i decided to improve the rf measurement section of the analyser with an ad8307 based power rf meter. The desig is simple and is popular among hobbyists. I got hold of an ad8307 in smd form, too small for me. So the challenge was to try some ugly construction using

Unknownnoreply@blogger.com5tag:blogger.com,1999:blog-8392959180134867028.post-53574636219938705822015-10-02T16:10:00.002+02:002016-01-05T14:22:39.432+01:00

Si570 home brew pcb for testing Si570 is a small usefull oscillator module from Silab (data sheet). It is a very small smd component with 5mmX7mm dimension. I recently procured a CMOS module for experimentation and amateur radio use. The device has 8 small pads of which 5 is really needed (in cmos version) to build a successful vfo circuit. It is used in popular BITX (from Farhan) and in

Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-8392959180134867028.post-78099127780286121472015-07-05T17:56:00.003+02:002017-12-30T15:00:47.490+01:00

Secure door lock with arduino and rolling code/code hopping with AES  In many of my weekend projects, i used some cheap 433 mhz RF modules or nrf23l01 modules for wirelessly controlling lights, temperature sensors, garage door openers e.t.c. But i never thought about the security for these protocols. It is pretty easy to sniff the rf signals with an sdr (software defined radio) and replay

Unknownnoreply@blogger.com34tag:blogger.com,1999:blog-8392959180134867028.post-23914735074667000702015-06-27T16:40:00.001+02:002015-06-27T16:51:02.854+02:00

A simple 433mhz rf module and arduino pro mini as a morse code beacon In this project a simple 433mhz rf module is used as a uhf beacon for testing purposes. This can be useful in fox hunting (locating hidden transmitter) or for finding lost RC models. An arduino pro mini is used for generating the morse code message, but any avr micro controller can be used. A simple rf module (with three

Unknownnoreply@blogger.com16tag:blogger.com,1999:blog-8392959180134867028.post-91441728768621162552015-04-12T18:47:00.003+02:002015-04-12T18:56:49.984+02:00

Measuring inductance and capacitance are not among the commonly available options in a simple multi-meter.  But often we need to measure an unknown capacitor or a hand made coil, for e.g while building oscillators and filters for qrp (radio transmitter) projects. Here is a collection of simple techniques which can be used to accurately (all-most as good as expensive tools) measure the values

Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-8392959180134867028.post-6779200229239724762015-04-02T13:11:00.001+02:002017-05-12T15:59:38.787+02:00

A simple SWR analyzer with ili9341tft and ad9850 DDS A simple antenna analyzer is a helpful gadget which will tell us about the frequencies to which a piece of wire will resonate on.  This is very useful in conjunction with a simple tuner to adjust the antenna for an optimum VSWR (voltage standing waves ratio). Usually, a good commercial antenna analyzer is an expensive device which we

Unknownnoreply@blogger.com66