Sep 102016
 

Do you ever use a transistor in an electronic project then pull all the components back off the breadboard and put them back in stock. And then when you’re ready to use them again you’re just not really sure it’s still in working condition. It’s a frustrating¬†learning situation when building an electronic project and for one reason or another it just doesn’t work, and you’re not confident all your components are working as they should.

Well here’s a project you might find handy to have on your workbench. It’s a simple transistor tester and if you have a dead 9VDC battery lying around then that would be the perfect power source for this project.

Components:

  • LED
  • 10K ohm Resistor
  • 680 ohm Resistor
  • 180 ohm resistor
  • SPST tactile momentary button/switch
  • Breadboard
  • 3VDC – 9VDC power source
  • Transistor to test

Schematic:

schematic00010002

Here is how you connect the components

 

 

 

 

 

 

Tester laid out on the breadboard.

Tester laid out on the breadboard.

 

 

 

 

 

 

 

 

 

Tester in action. Showing the NPN 2N2222 transistor is fully functional.

Tester in action. Showing the NPN 2N2222 transistor is fully functional.

 

 

 

 

 

 

 

 

 

Assorted button you can use.

Assorted buttons you can use.

Basic momentary tactile button is perfect for this project

Basic momentary tactile button is perfect for this project

Bottom view of NPN 2N2222 pins

Bottom view of NPN 2N2222 pins

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This project requires  less than $1 worth of components and can save you from much frustration. I hope you find it helpful. Now I need to make one that will test PNP transistors. So much to learn.

Happy electronic project building!

 

 

Jul 172016
 

 

Working with Level Shifterspresents400

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.

Step 1: Two channel level shifter
2 Channel Version

 

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.

  • AVCC (I soon figured out this was the 5VDC input)
  • ASCL – This seems to indicate the module is I2C compatible.
  • ASDA – In an I2C situation this would seem to be the SDA data signal connection
  • AGND – This pin goes to the ground bus

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.

Step 2: 3.3VDC HC-06 Bluetooth – 5VDC Arduino Pro Mini

LED Control Circuit

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/

The Arduino Bluetooth LED control sketch is avalable @ http://volthauslab.com/sketchs/Bluetooth/bluetoothLEDcontrol.ino