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. …
Author Archives: Justin Roeder
Laptop/Chormebook mobile charger
Have you wanted to take your computer with you but forgot to charge it and don’t have a portable charger. This do it yourself blog post will help. What you need My chromebook uses 19VDC @ 2.31A so I looked at eBay for a boost converter, this is because car voltage is only 12VDC it …
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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Elevens Solitaire
This game is a work of art! The rules are simple, in fact it may even be easier to win than regular solitaire! The object of this game is to discard all the cards by taking a pair of 2 cards and adding them up to 11. Jacks, queens and kings are only discarded when …
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 …
Christmas Light Contest 2023
This contest is to show your christmas decorations you put up this year. There is no prize but its just to show your christmas sprite. Voting ends 12/31/2023 and posting 12/25/2023. Note you can only vote once
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 …
Circuit Simulator