Tag Archives: projects

Electronics History: The 555 Timer

The 555 Timer IC (Wikipedia photo)

While researching for my last post about the plasma arc audio speaker, it got me waxing nostalgic about the 555 Timer Integrated Circuit, one of the most versatile ICs ever designed. The Plasma Arc Audio Speaker I wrote about was one of the coolest things I have ever seen built around a 555, which is a favorite and classic chip that first hit the silicon scene in the 1970s. Read more

Projects: FM radio with “old style” LED Bargraph Frequency display

Thorsten Singer’s FM Radio with LED Bargraph Frequency Display. Nice looking project!

Another gem from Instructables here.  This time it’s an FM Receiver with a custom LED Bargraph frequency display, brought to you by Instructables user Thorsten Singer.  The bargraph is cool and all, although I would probably add digits to the display to make it more tunable.  However, it’s a very well thought out project and nicely constructed, and it is something that you could use every day, so it gets points here.  Even the hand drawn schematic is classy.

 (image source: banggood.com)

TEA 5767 FM Receiver Module (image source: banggood.com)

It’s based on a TEA5767 FM Radio Receiver module that Thorsten bought from BangGood.com, who currently lists the price of these modules at 5 pieces for $5.51 USD, which is on par with some of the current Ebay prices.  The controller is an Atmega 328P chip with an Arduino bootloader (the Instructable has links to the source code as well).  It appears to have four pushbutton presets, and a rotary encoder for manual tuning.

Other than adding a digital display (I’d even go with a four digit LED display in lieu of an LCD, just to add class and glow to the panel).  I’d probably also add a dual LM386 amplifier circuit for the output.  This thing is so cool I may actually build one!

There is a short YouTube video below that shows the operation of this receiver.

Published from DFW, Texas



Crosstown traffic: Hackaday features my “FatFingerer” on their front page

Whether this was the result of people actually liking my project or just some random randomizer picking featured projects, I saw this on the Hackaday front page this evening (and no, I wasn’t logged into my account on Hackaday, and yes, I checked this from multiple browsers to make sure this wasn’t a cookie thing…) :

Screengrab from Hackaday, 11/14/2014 7:25 PM

Screengrab from Hackaday, 11/14/2014 7:25 PM

I detailed my FatFingerer to my friends on Facebook a number of months ago, I do plan on adding a detailed writeup to my blog in the near future… I use the FatFingerer every day at work when using AutoCAD and PLC applications, the heart of it is an Arduino Leonardo programmed to emulate common keystrokes.  And yes, if you’re interested in more detail right now, here is my Hackaday.io project page for the FatFingerer.


(published from Fort Wayne, Indiana)

Crosstown Traffic: Hackaday features Raspberry Pi-powered foxhunt transmitter — with or without an actual transmitter!

(my apologies about not posting in awhile.  I was on jury duty.  It was an emotionally draining case.  I’ll make up for it over the next few days.)

Hackaday ran an article yesterday that featured a hackaday.io project that Corey KM4EFP posted describing his Raspberry Pi powered Foxhunt transmitter.  What I found unique about this is that you can either feed the audio from a Pi output pin directly into a handheld transmitter, or actually transmit RF directly from the output pin (!) by adding a low-pass transmitter.  There is far more information about this project available on Corey’s GitHub page.  From the Hackaday.io project page:

My foxbox consists of a Raspberry Pi model B with Raspbian running pifox and is powered by a 6000mah usb power bank with a mausberrycircuits.com power switch and my gpio setup is laid out on an electro-resales gpio breakout pcb. All this is fitted inside a 30 caliber ammo can by use of non conductive foam padding. It starts transmitting automatically when the Pi is powered on and the transmit switch is flipped on. The transmission of my call sign and fox message and current time runs through gpio 4 and a lpf before reaching the antenna and also lighting an led indicating a transmission is in progress. No handheld is needed the Pi is the radio transmitter. You can also use audio out on the Pi to trigger vox on a handheld radio if your not comfortable building a low pass filter. Led and switches are also optional as well as automatic or manual transmissions and timing. Build your fox the way that suits you. There are many customizeable settings for pifox to fit your needs


We’ve seen directly driving an antenna from a GPIO pin before using PiFM.  I’m not sure I’d use it in any application where I would require frequency stability or any kind of a solid RF signal… but maybe the application of this is better than I originally thought.


(Published from DFW, Texas)

Projects: Software-Defined Radio with the RTL-SDR USB Stick

The RTL2832 and antenna

The RTL2832 and antenna

Yesterday I received my latest order from Adafruit — the RTL2832 Software Defined Radio USB Stick.  This nifty little device is sold in Europe as a digital TV receiver (DVB-T) for your computer.  While not compatible with the digital TV broadcasts in the US, with some additional free software, this little guy will tune into radio signals from about 24MHz to 1850MHz.  The “software” in Software-Defined Radio refers to the fact that an application external to the receiver hardware decodes the signal however you want — AM, FM (narrow or wide), single sideband, CW, etc.  The most popular Windows application (and yes, there are Linux programs available as well – the Raspberry Pi is a popular mate for this unit) for the RTL2832 is “SDR-Sharp.”  There are some more advanced applications available that will follow trunking systems and decode some digitial systems such as DMR, D-STAR, etc.  I haven’t downloaded any of these (yet).

Read more

Projects: RTL2832 Software Defined Radio and FM Stereo Transmitter from Adafruit

I just purchased a few items from Adafruit including an RTL2832 Software Defined Radio USB Stick and a Stereo FM Transmitter with RDS breakout board.  Not sure what I’m going to do with the FM Transmitter but I think it will be something like the FM Transmitter that my friend Mike Yancey KM5Z made a few years ago.  The Software Defined Radio stick will probably come with me on my travels so I can sniff the airwaves while bored in my hotel room.  Lady Ada has a good tutorial for the SDR and it looks like a lot of fun — will apparently pick up signals from 24 MHz to 1.8 GHz and supports narrow and wide FM, AM, sideband, and CW.  She also has a tutorial for the FM transmitter.  I’ll make some postings to the blog when I start playing with these things.


(published from Hagerstown, MD)