You can click here to see it. If you find it useful please buy a copy from your favorite e-book seller.
You can click here to see it. If you find it useful please buy a copy from your favorite e-book seller.
Level shifters are a wonderful and very affordable solution when you have a situation where you have to interface a 3.3VDC and a 5VDC device. They are also called voltage shifters and they come in uni-direction versions where the signal only goes one way, bi-directional where signal goes both ways, direction controlled level shifters with a dedicated directional pin, logic level shifters that put logic functionality and voltage translation into a single design, and finally application specific level shifters .You will also find them in a variety of multi-channel types as well as bit rates. In this article we’ll cover the 5VDC/3.3VDC bi-directional 2 and 4 channel types available on Ebay for a very low cost and how to use them in your ingenious projects.
This was my first level shifter. I bought it from a seller on Ebay. When i bought I had not yet worked with level shifting so I did not notice the module was not marked to indicate which side was LV (low voltage) or HV (high voltage). Simply put you supply 5VDC and GND (ground) to one side of the module and 3.3VDC and GND to the other side. The first time i used it I was using a 3.3VDC ESP8266 to wirelessly control a 5 VDC servo. Without the shifter the ESP8266 would not boot up. Once I had the shifter in place it performed perfectly.
The markings that are on the module are:prefaced with an “A” on one side and “B” on the other.
In this example I’m interfacing a 3.3VDC HC-06 bluetooth module with a 5VDC Arduino Pro Mini to turn on and off an LED using Putty on a BT equipped laptop.
I also bought some 4 channel shifters and they are marked HV and LV which tells me which side should be connected to the 5VDC power and which gets the 3.3VDC power. They are also marked TX and RX but I disregarded that in this setup and I am having no problems TXing on the RXing channel. I’ve breadboarded a 3.3VDC HC-06 Bluetooth with a 5VDC Arduino Pro Mini. using I’m using PuTTY ( a free SSH and telnet client for Windows) on a bluetooth eqipped laptop to control the Arduino to turn on and off the LED. You can get a free copy of PuTTY at http://www.putty.org/
Telerobotics is the area of robotics concerned with the control of robots from a distance,
mainly using wireless connections or the Internet.
The chapters are available at:
In our travels about the Internets we have came across many a helpful website. It is with much joy and satisfaction we share them with you now.
Electro Schematics is a treasure trove of projects (1089 electronics projects and circuits) we are sure will lead you further down the hobby electronic rabbit hole.
All About Circuits One of the largest online electrical engineering communities. A positive, open community of electronics geeks that enjoy sharing knowledge and ideas.
Talking Electronics – The legendary Aussie Colin Mitchell‘s website. This was what started it all for a generation of electronic hobbyists and future electronic engineers.
Instructables is a community driven website that has tutorials (ibles) and how-tos on anything you can imagine. Electronics is only a part of what is covered.
The title kind of says it all. If it’s electronics, it’s here. I tend to agree. Based in India this website covers almost every aspect of electronics. It’s worth it to (free) register with them for total access.
Let’s Make Robots is a total robotic community. Registration with allows you to actively share projects, news, videos and more.
Embedded Lab: An online teaching laboratory for Microcontrollers and Embedded Systems. A very good website heavy on microcontroller use in many projects.
Electronics Hub has a large selection of projects, circuits, and information that will prove quite helpful to hobbyists.
Arduinos are the main focus at tronixstuff. In fact they have over 50 Arduino tutorials.
David L. Jones is an electronics design engineer based in Sydney Australia. He hosts the EEVblog, the world’s largest and most popular engineering video blog and Youtube channel. In each episode he shares some of his 20+ years experience in the electronics design industry in his unique non-scripted naturally enthusiastic and passionate style.
Once a month or so the Volthaus Electronics Laboratory Team will make the rounds of various thrift stores (i.e. Goodwill, etc.). Recently while browsing we found two Altec-Lansing Powered Sub-Woofers. One was priced @ $5USD and the other one was $10USD.
They were originally a part of a 5.1 computer speaker system but when found, it was the sub-woofers only. They were purchased and brought back to the lab for tear down. They have proven to be loaded with high quality components. The first thing found of course were the speakers. The smaller of the two was 4in and the larger was a 6in and they were obviously well made.
Inside each one was a very larger number of components such as Samxon capacitors in a variety of values, several TDA Op-Amps (TDA7265, TDA7294, TDA7482, etc.), hardware, and each one had an AC transformer featuring multiple VCT voltages. Just guessing, somewhere in the neighborhood of $100 worth of parts per sub-woofer were salvaged.
The only problem with these powered sub-woofers were they were missing the satellite speakers, one of which in each system contains the controls. All in all an excellent find of components at a truly rock bottom price.
And everything recovered from them works perfectly. Possible future plans call for the cabinets, speakers, and some of the other salvaged parts to be used in two projects. The projects are high wattage, lab built guitar and bass amps. The second powered sub woofer (100 watt) contained a massive toroidal transformer.
These transformers alone are worth anywhere from $25USD to $50USD or more. Which brings us to the question:
Knobs average in price from .50 centsUSD for a functional but not very attractive knob to $1.50USD for a Marshall amplifier style. When you see a quality knob, grab
it, you will be so glad you did! It takes only seconds to remove a knobs and it is so helpful when building a project you can just reach into your storage drawers and get one, put it on and proceed with your masterwork.
The switch is one type of electronic component that is ever rarely discontinued. Through the years, I’ve found switches on rack mount audio gear, mixers (goldmines for knobs), ancient VCRs (miniature push-buttons off their PCBs), from multi-function printers.
And of course from amplifiers. I go for the input selection multi-pole rotary encoder switch. I’ve found them in abandoned cars dashboards.
Switches come in all shapes and sizes and is one electronic component that doesn’t go out of date.
A fried desktop computer power supply can give you plenty of stranded copper wire. Even the case it comes in can be re-purposed as a project enclosure. And the hardware that holds everything in place can, and will become useful. An old computer is a treasure trove of bolts, stand-offs, etc. Everything you salvage from one is less that goes into the dumpster. Good for you and good for the planet. And your wallet.
A glass fuse and its fuse holder are just as useful today as it was years ago.
You can find fuses and their holders from all sorts of equipment.
If the fuse holder is an inline type (The little two piece holder in the voltage supply wire: think CB radio, radar detector or 8-track player: Yes i said 8-track player) or easily removed chassis mount design.
You can also obtain very useful fusible links from car fuse and relay boxes, and much industrial equipment contains re-settable circuit breakers.
I have also salvaged the two different sizes of blade fuse used in vehicles. I have an old commercial prototype 12v to 110v inverter and they soldered the blade fuse directly to the PCB. Once bypassed (it was easier to leave it in place and solder in a new one) the inverter works perfectly.
It’s not at all hard to collect enough fuses so you’ll never need to visit AutoZone to buy one again, or wait while an affordable one is shipped to you from China.
Relays are very useful, rugged (basically impossible to blow up), universal within voltage and current restraints, and easy to wire into place. And their usefulness is increasing. Via the Internet of Things so many appliances can be controlled through either your home network or the internet. An enormous range of equipment and appliances have relays inside which you can easily collect one from even moderately complex bits of gear you salvage.
Relays (and many other parts) can be removed from PC boards quickly and effortlessly by using a heat gun aimed at the solder side of the board and plucking out the relays with pliers. I remember picking up an ABS (anti-lock braking) controller from a car and realizing it contained no less than six small, high current 12V relays.
This is a fairly recent development in automotive salvage and a set of four removed from a automobile at a salvage yard can cost you around $30USD. But they are quite a bit more powerful than an Ultrasonic Ranging Module HC-SR04 and all-weather also.
The LED has become so low in price that salvaging them may seem like a waste of time, but if it is something special like an RGB for instance I will definitely take the time to remove it and deposit it into my container marked “exotic LEDS”.
It’s easy to salvage LEDs that are special to you for some reason. Those with odd lens, unusual shapes (I love those), and LEDs in shades of colors you might not normally see. And using the heatgun method mentioned earlier you can quickly recover handfuls of LEDs so go get em’. They are free.
While I’m not a huge fan of trying to stock up on recovered plugs, sockets, etc. there are a few exceptions to that rule. The RCA female sockets are particularly useful when building stereo amplifiers. Also another socket (jack) I will go after is the female 1/4in phone jack you find on instrument amplifiers and the instruments themselves. They cost an arm and a leg brand new so I get those every chance I get.
You should visit my heatsink museum if you ever get the chance. Heatsinks are found in discarded computers in a huge range of sizes. From small ones that cover the chipsets to large heatsinks that are attached to the CPUs And there are huge ones in power supplies and in audio amplifiers. If you’re building projects it really pays to have a large variety of heatsinks on hand because many of the modules you attach to Arduinos and other microcontrollers need a heatsink if you want them to operate reliably.
Take my ENC28J60 network adapter module for example. Many people swear they can only get them to work when pumping 5v into them. I tried and it did work but the ENC28J60 IC became so hot I am sure you could have easily fried and egg with that amount of heat. And in no time at all it started acting unreliable. Now I have had great success running mine at 3.3v. There is a DHT22 sensor connected to an Arduino Nano in the laboratory that is running a webserver sketch, and it has been operating for at least 6 months now, day and night, week after week with no problems. Check it out at http://volthauslab.ddns.net/ It runs great for me on 3.3v but it still gets quite hot and I have heard other people say it worked for them a short while then quit and I’m positive heat is playing a major part in its lack of reliability. I made the holding clip from a basic paperclip and i also added a dab of thermal paste between the sink and the IC.
Motors are everywhere and you should not be letting a single one get away. You can find motors of two types in almost every malfunctioning CD or DVD drive. The rotary motor that spins the disc plus a neat little worm gear stepper motor. And you can also find stepper motors in printers as well. If you want the large motors you can salvage them from home appliances like dryers and washing machines. Those are just a little out of our league (currently that is).
Good luck because you’re going to need it once you begin to get your collection together. Getting organized and staying that way is a real challenge (fun). And we didn’t even cover what you can pull out of old CRT televisions and other things, but I think this is a good start. Have fun, be safe, save money and build wonderfully fascinating things!