My Projects - 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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4-in-1 Analog Calculator

Justin Roeder — Tue, 09 Jul 2024 19:08:58 +0000

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.

Multiply

Again if there are any unused pots set them to 0

Divide

In this animated circuit shows you how the resistors divide the voltage. The resistance isn’t important. You probably want nothing lower than 2.2k(for 32.5v, which is probably the max my adjustable voltage source will give you.) To figure out the current rating use this equation $$I_{max}=\frac{V_{in}}{R}$$ To use that circuit first measure the voltage source output(The numerator of the fraction). Then tap into the resistor chain(the denominator of the fraction). The voltage output from the resistor chain will be the Quotient. You can use any number of fixed resistors and any reasonable value as long is impedance doesn’t go too high where the current is too weak for your meter to pickup. You also don’t want to go too low where your batteries leak or explode or even the resistors could catch on fire if the wattage goes over the rated resistor wattage.

The adjustable voltage source

Here it is. This will give the numerator any number between 1.25 to 32.5. I plan on powering it from 4x 9v batteries. This will provide 36vdc of power. You can use anything from 40v or less. If anything higher is needed you can build a rectifier diode chain, I’m not sure if it’s accuracy is any good. Any adjustable linear voltage regulator is good for this purpose To change the voltage range on the LM317 click here.

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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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The easiest RJ45 Cable Tester

Justin Roeder — Thu, 18 May 2023 21:41:35 +0000

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.

First cut and strip the USB Cord so that red and black wires are available to solder. Solder the white wire of the pair to the negative end of the switch and the solid color goes to the positive end of the switch like shown in the circuit diagram. The red wire will be connected to the resistor and the other end of the resistor is common + for the switches(solid color). The black is the ground for the switch(white wire of the pair). See figure 1 for RJ45 twisted pairs colors, include all 8 pins including the not connected.

Figure 1. RJ45 Pinout(note that it may use 1 and 2 as the orange pair and 3 and 6 as green pair)

Figure 2. USB Pinout

Figure 3. Per Twisted pair

To use simply turn one switch at a time to test the polarity of the twisted pair. Checkout the table below for test results.

Twisted Pair	Straight-through	Crossover	Rollover
1 and 2	Positive 1 and 2	Positive 3 and 6	Negative 7 and 8
3 and 6	Positive 3 and 6	Positive 1 and 2	Negative 3 and 6
4 and 5	Positive 4 and 5	Positive 7 and 8(1Gbps) or positive 4 and 5	Negative 4 and 5
7 and 8	Positive 7 and 8	Positive 4 and 5(1Gbps) or positive 7 or 8	Negative 1 and 2

Figure 4 LED Polarity Truth Table

The bold results are not needed for 10/100Mbps connection. Of course you could use a arduino,counter chips or flip flops. But that wouldn’t be the simplest tester.

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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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