Saturday, October 30, 2010

Radio Fundamentals PDF Download

If you are interested in learning the basics of radio wave propagation, transmission lines and antennas here is a great PDF file for you to download. "COMMUNICATIONS-ELECTRONICS FUNDAMENTALS" This 269 PDF from the headquarters department of the army is a great way to get started in learning about the basics of radio.

Click here to download.

If you have trouble with the link email me and I will email you a copy.

Remember to visit

Thursday, October 21, 2010

Amateur Radio

Amateur radio also called ham radio is an awesome hobby and lots of fun. If you are already into electronics and enjoy studying radio theory than this is most likely a hobby you would really enjoy. Preher-Tech has added an amateur radio page to our website that includes basic info on amateur radio as well as a list of all the books you will need to get started in this hobby. I myself am a general class operator, my call sign is KF7LTV
and I am planning to go get my amateur extra license very soon, giving me full privileges on the amateur bands. Hope to hear some of you on the air soon. Click here to visit our amateur radio page.

Don't forget to visit for all your electronics needs.

Tools and Test Equipment

Well per the request of many viewers and newsletter subscribers and many random emails we finally decided to add a sales page to our website featuring all our favorite tools and test equipment including digital multimeters, analog multimeters, tool kits, soldering stations, SMD rework stations, oscilloscopes, LCR and ESR meters and more. We are looking for suggestions as well so tell us what you want to see on the page and we will do our best to make it happen. Thanks to everyone for all your support over the years and we look forward to servicing you into the future.

Cick here to visit our new "Toools and Test Equipment" page

Also don't forget to come visit

Tuesday, October 19, 2010

Electrolytic capacitors

An electrolytic capacitor is a type of capacitor that uses an electrolyte, an ionic conducting liquid, as one of its plates, to achieve a larger capacitance per unit volume than other types. They are often referred to in electronics usage simply as "electrolytics". They are used in relatively high-current and low-frequency electrical circuits, particularly in power supply filters, where they store charge needed to moderate output voltage and current fluctuations in rectifier output. They are also widely used as coupling capacitors in circuits where AC should be conducted but DC should not. There are two types of electrolytics; aluminum and tantalum.

Electrolytic capacitors are capable of providing the highest capacitance values of any type of capacitor. However they have drawbacks which limit their use. The voltage applied to them must be polarized; one specified terminal must always have positive potential with respect to the other. Therefore they cannot be used with AC signals without a DC bias. They also have very low breakdown voltage, higher leakage current and inductance, poorer tolerances and temperature range, and shorter lifetimes compared to other types of capacitors.
Read the full article by clicking here.
Don't forget to visit for electronics repair and design information. You may especially want to check out our tools and tips page by clicking here.

Switching-Mode Power Supply Design

I found this wonderful site with lots of tutorials on SMPS design and you can also join their news letter to get great SMPS design information sent to your inbox.
Click here to see this great website.
Also remember to visit

Opto-isolator Tester

One of my newsletter subscribers sent me a picture of the preher-tech opto-isolator tester which he had built from the parts list and schematic I had included in my article on testing opto-isolators. He did such a great job even etching a PCB that I had to share the pictures of his work with all of you. Great job Beh!
Note: Beh switched the LEDs so red indicates power on and green indicates a good opto-isolator.
If anyone else has pictures of there opto-isolator tester built from my design please send it to me and I will post it here to share with everyone. Email pictures to
Also if you missed the article on testing opto-isolators you can download it by clicking here.
Don't forget to visit

Sunday, October 17, 2010

Laptop repair guide

•Do you want to learn how to fix laptops?

•Are you afraid to work on laptops for fear of breaking them?

•Do you want to expand your skill set so you can make big money fixing laptops instead of sending the business away?

•Receive the same high level of Podnutz quality, as Steve releases the long awaited Laptop Repair Video Collection!

What do you get in this package? You'll see in full 960x540 HD video:

•How to replace a motherboard
•How to replace an LCD Screen
•What to do when the laptop keeps shutting down
•How to fix DC power jacks
•The crucial difference between a bad screen and a bad inverter board
•How to replace hinges
•Where I buy all my parts
•The best way to go about taking a laptop apart
•How to solder
•The art of fixing AC adapters
•How to handle a laptop that has had liquid spilled in it
•what to do when a laptop overheats
•how to replace CD/DVD drives, RAM, processors, hard Drives and wireless cards
•and much, much more!!

Click here to go to the sale page and learn more about the "Laptop Repair Video Collection" including customer testimonies.

Tuesday, October 12, 2010

Learn basic electronics and electrical engineering

Take a look at this new guide by Greg Carpenter, "Introduction To Basic Electronics". This guide will get you started with all the basics of electronics the easy fun way, at home and at your own pace.

Click here to learn more about this great guide "Introduction To Basic Electronics" and get started learning about electronics today.

Don't forget to visit and also if you ever have any electronics related questions remember you can always email me

How to repair LCD TVs

Are you looking for a guide to show you how to fix LCD TVs? If so then you may want to take a look at "Troubleshooting and Repairing LCD TVs". Whether you are a technician that is looking to expand your repair skills or just someone who has a broken TV that wants to repair it at home and avoid repair costs or replacing your TV than this is the book for you. 195 pages and only $25.00 and this ebook even comes with email support from the author John Preher. So don't hesitate to grab this guide today and start fixing LCD TVs.

You may also be interested in "LCD TV Repair Case Histories" if you are looking for a quick fix for your LCD TV. Click here to learn more about "LCD TV Repair Case Histories".

Wednesday, October 6, 2010

ShopJimmy UK

We are pleased to announce that ShopJimmy has fully launched their UK website.

That's right!! The same smiley face in a brand new place.

To visit ShopJimmy UK click here.

Tuesday, October 5, 2010

Understanding and testing opto-isolators

An opto-isolator also called an opto-coupler or photo-coupler allows a signal to pass from one circuit to another but allows the two circuits to remain electrically isolated. The most common opto-isolator which comes in IC package consists of an LED which shines onto the base of a photo-transistor (usually an npn transistor) and allows current to flow from collector to emitter until the LED is turned off. When a signal is applied to the LED it then shines light that is varied in brightness with the same amplitude as the input signal, this light lands upon the photo-transistor (the resistance of the collector/emitter junction now changes with the varying light) which passes the signal onto the next circuit.

Basic opto-isolator symbol.
If you do a lot of work on switch mode power supplies than you have surely seen the opto-isolators used in the feed back section of the power supply.

Opto-isolators in LCD TV SMPS.

If you want to read more about opto-isolators including my 3 methods for testing them than dowload my free article "Understanding and Testing Opto-isolators" by clicking here.

Included in the article is a schematic and parts list for a simple opto-isolator tester.

Don't forget to visit and also if you have any electronics related questions you can email me for assistance.

Recommended Repair Guides:

LCD TV Repair Guide

LCD TV Repair Case Histories