This is a TL431 comparator fuse that can be made on a breadboard,pcb or even copper tape. It uses a 1.5V Battery(Can be AA,AAA,C or D). Its used to add 1.5V to the voltage drop across the current sense resistor. This is needed since it can only turn on at 2.5V at the reference pin. …
Category Archives: My Projects
4-in-1 Analog Calculator
Here are ways to do addition, subtraction, multiply and divide using a multimeter. Addition Addition is very simple! To do it just connect some pots in series. With series resistors their resistance adds up. Subtraction NOTE: If there are 3 or more pots in series, just set them all the way down to 0 ohms. …
Clockwire Parallel Port Binary and Digital controlled clock
This program allows you to wire up a 2-digit Binary clock, Digital clock or both. It uses inpout32.dll file to output the time on the data register. I used a rj45 to db25 male module to make connection to my parallel port and the clock. There are 8 wires (9 if you want the hour …
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Resistor RJ45 Tester
This is a simple network cord tester that uses just 8 unique resistors. The values/wattage doesn’t matter as long as the meter can read them. They should be in the kiloohm range. I have made an Excel spreadsheet file that you can enter all 8 of the resistors and get the total parallel resistance. The …
Basketball pump signal injector
This is a simple signal injector that can fit inside a mini basketball pump it requires: This signal injector can come in handy for repairing radios, amplifers and old TVs and also square wave generator in a probe. Later on I will make a version that uses C1 and C2 as 470nF and R3 and …
Simplest Wire Tracer/Coax Tester
This is a simple wire tester all you need is a 12-1000vac non-contact voltage detector. The ideal is to connect AC live wire to the red circle is. You do not use ground or neutral wires, these wires should be cut off. If the cord is shielded(coax) the detector doesn’t. Even though there’s only one …
The easiest RJ45 Cable Tester
This tester is pretty simple and cheap to build. All you need is 2x RJ45 Female connectors(like the ones for putting into the wall) 4x 2-pin Bi-color LEDs 4x 150 ohm resistor USB A Male Connector(I cut a USB Cord) 4x DPST or DPDT Switches A PCB Or floor tile and copper tape Some wire. …
USB Null Power Supply
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 …
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 …
Circuit Simulator