Recent Posts

555 Timer Output Stage (Lens Detector Part 2)

555 Timer Output Stage (Lens Detector Part 2)

The 555 timer has many uses and in this video we’ll explore two different ways to utilize the output. First we’ll see how the the timer can be used to source and sink current and secondly we’ll look at a way to use the timer […]

How a 555 Timer Works (Lens Detector Part 1)

How a 555 Timer Works (Lens Detector Part 1)

I am slowly in the process of developing another class, but this time I want to go about it a different way. I’m going to be letting everyone else in on the process. The coming class will include a lot of projects, so during the […]

How to Build a Passive Network Tap

How to Build a Passive Network Tap

In the course of my normal job, it’s surprising how often field expedient solutions are used to solve a problem. However, those field expedient solutions are impossible unless you understand the underlying principles involved. In this video I’ll look at Ethernet infrastructure, discuss how it works, […]

9 Volt, Battery Powered, Telephone Intercom System

9 Volt, Battery Powered, Telephone Intercom System

When I was developing the VoIP Fundamentals course, I wanted a demonstration to illustrate the simplicity of the public switched telephone network. After combing through the internet, I came across this ingenious little project. With just a 9V battery, a resistor, a telephone cord, and a […]

Auto Answer: Feature or Vulnerability

Auto Answer: Feature or Vulnerability

Auto Answer is a feature in many VoIP phones that allows the phone to go off-hook the very instant a call is received by the instrument. In this video we’ll look at how this feature is setup and talk about the security vulnerabilities. NIST Report: Link […]

How to Listen to VoIP Conversations with Wireshark without Capturing the Call Setup

How to Listen to VoIP Conversations with Wireshark without Capturing the Call Setup

Sometime when performing a packet capture, you may come across some VoIP conversations. If the initial call setup is not in this capture, subsequent voice packets will be labeled in such a way that it makes it difficult to decode the VoIP conversation. What follows is […]

VoIP Dialing Without a PBX

VoIP Dialing Without a PBX

At one time I had the misconception that you had to have an IP PBX to use a VoIP phone, but it’s simply not true. In this video I’ll show you how to dial another VoIP phone without routing through the PBX or SIP Proxy. […]

The Griffin Audio Preamplifier Demo

The Griffin Audio Preamplifier Demo

After months of questions I’ve finally decided to make an online video describing the Griffin Audio Preamplifier. The cost involved with making this video was huge, but I’m just the one to pay the price. REI Talan: http://www.research-electronics.com/cgi-bin/main.cgi?action=viewprod&ct=products&num=DPA-7000

Amp Mods, Skinny News, and Charity

Amp Mods, Skinny News, and Charity

Happy New Year Everyone! I hope your holidays were refreshing and filled with hope, family, and friends. In this video I’ll be talking about a modification on the LM386 amp design used in the KiCad tutorial, we’ll discuss using a stereo output jack with a […]

A Beginners Guide to the LM386 Amplifier Circuit

A Beginners Guide to the LM386 Amplifier Circuit

After creating the amp in a jar by using KiCAD, I felt like it would be appropriate to review the workhorse in the circuit. So today’s video as a tutorial about how to use the LM386 audio amplifier. If you have any questions feel free to […]