One time I read an Nuts and volts article where this guy took a usb cord and unhooked the +5v(red wire) and made it where the arduino can be powered by an external power supply without breaking anything.. This can be also handy for power hungry devices(such as external dvd burners,etc). This will draw nothing …
Tag Archives: diy
0-30v/0-60v dual power supply
Here’s a type of powersupply you should have. It’s good if you’re dealing with OP amps. I took the circuit from eleccircuit.com and modified it to incorporate 2x printer power supplies instead of an AC transformer. It provides a ground that are both positive and negative. LM317 and LM337 regulators are utilized in this circuit. …
Audio over telephone
Heres a simple circuit that takes a audio signal(from ham radios,computers or cd players) and converts them into a telephone signal. It powers the phone line with 22vdc(It doesn’t have to be 22vdc, different voltage means different resistor is needed). The phones can run as high as 48v. If you use cordless phones the converter …
Capacitance substitution board
In this blog I will show you how to make a dip switches capacitor substitution board. Its very simple since capacitors add up in parallel. So if you look at the schematic you will get an idea.
Simple doorbell/alarm
This is probably the simplest doorbell or alarm circuit that is out there. The buzzer will not be constantly on since the buzzer gets switched on by a capacitor. The circuit draws hardly anything when off as you will see in the graph below. As the capacitor gets charged its current lowers down a lot. …
Arduino Video poker for the TV
Here is a project I have been working on. It hooks up to the tv and allows you to play 5 different types of video poker games. The game is in black and white and some of the suits look funny. The pinouts can be found in README.MD file. Youtube videos
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 …
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 …
Solder Iron Foot Switch
This switch is a must for people who solder alot. It prevents the iron from overheating. Its very simple and is very cheap. Some irons like mine can heat back up fast after they have not been cooled down alot. You will need the following parts and tools: 1 foot pedal switch SPST 1 duplex …
