Author Archives: Justin Roeder
Discrete transistor op amp
Here in this blog i will show you how to build a high powered transistor opamp. The design is based off of allaboutcircuits.com design. The only changes were the transistors were power transistors and rprg is lowered to 390 ohms half watt.
Capacitor powered LED flashlight
Long time ago QVC sold a shakeable Flashlight that had no batteries just a shakeable generator and a super capacitor. This flashlight uses a 5vdc 1.5a wall wart to charge the capacitors. To figure out how long it will take to charge the flashlight you use this equation $$T=5R_{currentlimit}C$$ And for total discharge time $$T=5R_{LED}C$$ …
Yet another TV oscilloscope
In this blog post a crt TV a part and turn it into a oscilloscope. I am going to try to use a TL082 op amp to buffer and amplify the signal. It uses the deflection yoke to draw the picture on the tube. More pictures and videos will be posted here when it is …
DIY Static wrist strap
This wrist strap prevents electrostatic discharge to whatever you touch What you need: 1 meg ohm resistor(any wattage or tolerance will do Copper tape or foil a piece of wire(you can use all of the wires from a btoken cord if you like0 bracelet(This should allow the copper tape to stick) one alligator clip Step …
DIY anti-static mat
This is a very simple esd mat that anyone can build. All you need is Small nail Cardboard box A three prong cord(must be three prong so that it functions correctly) Copper foil sheets that stick(i got mine from eBay, it is used for guitars) 1 meg ohm resistor any wattage should do. Hot glue …
Simplest analog computer
In this post I will show you how to make a analog computer using just resistors, switches and a 100 micro ammeter. Here’s the schematic of it: You can see the idea on how this analog computer works, it uses ohms law to get current from resistors in the circuits. Each current is limited in …
Icon Screensaver
This screensaver does exactly what the name says. It looks for icons and have them bounce around the screen and leaving a trail behind them. They are randomly chosen from windows, system and cursors directory. It uses ExtractIcon function from shell32.dll to get the icon and number of icons.
Random Screensaver for windows
This screensaver randomly chooses screensavers when it starts. You can choose which folders to use, how long of a delay between screensavers and which ones you don’t want running.
AutoRecord for NCH SoundTap
I wanted soundtap to keep recording after a song was done playing on YouTube so thus AutoRecord tool was made
Circuit Simulator