diy - Delphijustin industries

Simplest Variable Fuse

Justin Roeder — Tue, 10 Sep 2024 14:52:13 +0000

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. The 431 can be found in a lot of switching power supplies, just look for a tiny transistor looking device containing the number 431. This fuse is better than poly fuses and circuit breakers.

Here are some equations for current sense resistor:

$$R_{sense}=\frac{1}{I_{trip}}$$

$$P_{sense}=I_{trip}^2R_{sense}$$

$$V_{max}=\sqrt{R_{sense}P_{sense}}$$

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Laptop/Chormebook mobile charger

Justin Roeder — Mon, 12 Aug 2024 16:53:37 +0000

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

A soldering iron
2.2k resistor(Optional power led resistor)
a LED or more(if you want lighted Cigrette lighted sockets)
A Resistor that is $$\frac{12_{V}-(n*V_{F})}{I_{F}}$$ Where Vf is the LED Voltage Drop, n is the number of LEDs and If is current usually 20mA
DC-DC boost converter that outputs the same voltage as your charger but runs on 12vdc
A spear ac adapter to salvage the connector that fits the computer(I used one from a old motorola cellphone charger adaptor that I got from a hamfest)
Cigrette ligher cable. Got that from the hamfest as well!
Female Cigrette lighter connector I got two of them with 3 connectors each for free.
Heatshrink tubes(Prevents short circuits)

My chromebook uses 19VDC @ 2.31A so I looked at eBay for a boost converter, this is because car voltage is only 12VDC it needs to be stepped up. The chromebook may run from 12VDC directly it probably won’t charge. I got a 3 female Cigarette lighter socket from a hamfest and add 3-green LED in series with a 240-ohm resistors and put them close to the hole in the middle of socket, making the sockets lighted.

Steps

Cut the cord with the end that fits the computer. DO NOT CUT IT TOO SHORT BECAUSE WE WILL USE THAT PIECE TO ATTACH THE BOOST CONVERTER TO THE COMPUTER.
Use your multimeter to find the wire that goes to the tip(Center usually +) and the sleeve(Usually ground). Solder them to the output of boost converter. You may want to attach it to a insulator on copper tape if your going to add a LED.
Connect the LED with the anode(before the arrow on the LED symbol) to resistor and +Vout and cathode(the line, after the arrow symbol) to ground This LED lets you know if its on, wired correctly and has enough juice to power the computer(it will flicker/blink if the computer overloads the boost converter
If you want to light up the cigarette lighter female plug just put them close to hole where the center +12v is. You can wire them in series for multiple jacks, like in the circuit below. The formula for the resistor is $$R_{1}=\frac{12-(V_{F}*n)}{I_{F}}$$ where Vf is the forward voltage drop n is the number of LEDs and If is forward current.

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Clockwire Parallel Port Binary and Digital controlled clock

Justin Roeder — Tue, 23 Apr 2024 14:40:14 +0000

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 and minute indicator). RJ45 has 8-pins so it works.

System Requirements

Windows 2000 or higher (32-bit Windows recommended)

A parallel port that supports the registers (most USB adaptors do not support it, they only support printers)

All programs are virus free. Some antivirus software might say its "suspicious" or a "Potentionaly Unwanted Program". Some of them rate them on what there code looks like no matter if theres a definition in the virus database. If any of them are detected any Antivirus I will zip the software with the password "justin" j is lowercase

pinout

digital clock interface

windows xp screenshot

Purchase Source Code $1.28

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Resistor RJ45 Tester

Justin Roeder — Fri, 08 Dec 2023 20:01:40 +0000

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 pins are listed as binary 1s and 0s. J1 and J2 are the RJ45 connectors. I even entered the ones I’m using. It doesn’t tell you if it’s a patch cord, crossover or rollover, but tells you if the pins used on the cord are making connection. To tell what type of cord it is just look at the 2 ends.

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Basketball pump signal injector

Justin Roeder — Sat, 18 Nov 2023 00:29:57 +0000

This is a simple signal injector that can fit inside a mini basketball pump it requires:

1x dc blocking capacitor(10nF to 10uF) C3(2.2uF Axiel Film Capacitor)
2x 100nF Capacitors C1 and C2
2x 1k ohm resistors R1 and R2
2x 4.7k ohm resistors R3 and R4
2x General Purpose NPN low power transistors Q1 and Q2(I used PN2222A)
A 1.2 to 14v dc power source
A alligator ground clip

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 R4 as 1 Megaohm and C3 as 47uF(Since the frequency is ultralow).

The specs

Where R=R2 or R3, C=C1 or C2 and $C_{3}$=C3

Frequency: $f=\frac{1}{1.38RC}=1.5kHz$

Output AC Resistance: $X_{C3}=\frac{1}{2\pi*fC_{3}}$

PCB Files

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Simplest Wire Tracer/Coax Tester

Justin Roeder — Thu, 09 Nov 2023 02:00:49 +0000

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 wire used you should not touch the wire. The 5v is actually the ac mains voltage. The three switches choose 1 out of 8 outputs to connect the ac live wire to.

Whats needed

1x spdt switch
1x dpdt switch
1x 4pdt switch
1x RJ45 Jack
1x Polarized ac power cord
a project box that is big enough to fit everything
MultiMeter
screwdriver
drill

drill holes in the box for wires and switches
connect all switches as shown in the picture at the top. NOTE THAT THE LAST SWITCH OUTPUTS GO TO THE RJ45 JACK
Next set your multimeter to lowest resistance range and check for continuity between live wire pin and rj45 connector. this will help find the correct pinout on the switches

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USB Null Power Supply

Justin Roeder — Fri, 21 Apr 2023 20:24:41 +0000

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 on the computer.

Schematic Diagram Left side is the computer Right side is the USB device

Parts list

1x USB Extension Cord

cheap heatshrink assortment

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0-30v/0-60v dual power supply

Justin Roeder — Mon, 03 Apr 2023 16:48:35 +0000

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. They are the main components of the circuit. It uses 2 diodes and a 2.2k 2W resistor for each regulator’s adjustment to 0v. It has 3 diodes for each regulator to be used as its protection diodes like capacitors and short circuits. The two 5K potiometers adjust the output voltage at each output. Printer power supplies are perfect for this project since their voltages are not too high or low.

The project is built on a dick Tracy lunch box. With the printer power supplies inside with a c7 power cord splitter. It uses LM317 and LM337 to provide both positive and negative voltages. Here’s a joke: So I guess that means the LM317 and the LM337 are like the yin and yang of electronics!

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Audio over telephone

Justin Roeder — Sat, 14 Jan 2023 22:07:10 +0000

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 will still need power. WARNING DO NOT CONNECT THIS TO A REGULAR TELEPHONE LINE OR LANDLINE THOSE LINES PROVIDE AC AND THE CAPACITOR WON’T BLOCK THE VOLTAGE. THIS CIRCUIT IS TO TAKE AUDIO FROM THE HEADPHONE JACK AND INJECT IT INTO CORDLESS PHONES WITHOUT A TELEPHONE COMPANY. I use mine to listen to IRC chat 1000ft away from my computer. This could also work with corded phones. I believe you connect them in series, where the lamp is. I don’t have any corded phones to experiment with, the resistor may need to be lowered for 2 corded phones. I tried connecting two cordless phone bases together but the handset said No Line and also you could hear them or hear the tone when you press number buttons. When I made this circuit the No Line message went away and you could hear the computer and tones for the number buttons could be heard.

The capacitor should be no more than 1uF of capacitance and non-polarized. And yes the cord is safe to touch since its not hooked up to a real phone line. The resistor should be 1/2W instead of 20W. I had extra of those so I used it.

In the circuit diagram the 44KHz is the Audio Signal and the lamp is the phone

The way I wired it. Part of the audio cord is behind the RJ11 and the other one by GND
The schematic

I have two cordless phones but no splitter or second RJ11 connector. I will try talking over them when I get those stuff

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Capacitance substitution board

Justin Roeder — Mon, 01 Aug 2022 00:51:27 +0000

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.

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