Diodes basics 101


#1

Disclaimers:
It is the end user’s responsibility to see to and to carry out proper implementation their own repairs and modifications. Ultimately the end users hold responsibility for how they implement their own repairs.
This guide assumes you are familiar with basic understanding of electricity and than you can build a simple electronic circuit. I am only going to cover the basics and what fits in the preview of Tech Talk.

What is a Diode?
The ideal diode is to control the direction of current-flow. Current passing through a diode can only go in one direction, called the forward direction. Current trying to flow the reverse direction is blocked. They’re like the one-way valve of electronics. –Sparkfun
That a Diode has low (ideally zero) resistance to the flow of current in one direction, and high (ideally infinite) resistance in the other. –Wikipedia
A Diode can be made from a vast selection of materials, the actual semiconductor as well as the outer case.

What type or diodes are out there?
Regular/Signal Diodes
Zener Diode - useful in creating a reference voltage or voltage stabilization
Diode Rectifier – often used for reverse voltage protection
Bridge rectifier (also known as a diode bridge) – often used to converts AC to DC, can be purchase as a single component or made from 4 or more diodes.
Schottky Diode - known for their low forward voltage drop and a very fast switching action
Light Emitting Diode or LED – used for low voltage light. Some LEDs produce infrared or ultraviolet light instead of visible light.
Photodiode – a Diode that converts light into electrical current. Traditional solar cells are an example of a photodiode. So are Diode light sensors.
Thermal Diode – use to electronically monitor temperature

Why we [at Tech Talk] should care about Diodes?
Other than the obvious LEDs for lighting, diodes are often also used for pad hacks, rectifiers on power supplies and other applications when we want to electrically isolate something.

How to “wire up” a diode?
Every diode has two (2) terminals and they are polarized. The two terminals are the anode (+) and cathode (-). Current flows from the anode end to the cathode, but not the other direction.

As you see in the image above their is the symbol for diodes use in circuit diagrams as well as two illustrated examples of a diode.
The stripe on a diode identify the cathode end of the Diode.

Pad Hacks
Some PCBs for Dual-Mods require diodes to be installed. The Diode is soldered to the signal line/pad/terminal of the PCB with the other end going with that button signal line to the rest of your Dual mod.
The anode (-) end of the diode is to be soldered to the PCB and the cathode end going towards your buttons.

For your particular board please address your boards relevant guide/thread.
Thirdparty PS4 Padhack options - Third party PS4 padhack options

For those who don’t know what diode to use, almost any normal diode would do. You can get away with using a Zener, Schottky or rectifier diode.
Don’t worry about the amperage for the diode as the PCB should operate in lower range that the maximum amperage for most diodes.
I recommend a simple signal diode, examples are Digikey, part # : 568-1360-2-ND or Mouser Part #: 771-1N4148-T/R

Diodes can also be used in conjunction with other components to make a PCB that not common ground to be compatible.

LED Lights
The two terminals of a LED still have the same designations as other diodes, a anode and cathode end but there markings are different.

Almost always the Longer leg of the LED is the Anode and the shorter leg the Cathode terminal. The LED it self will also have a flat side indicating the cathode side.
SMD LEDs will have a mark with resemblance to the symbol for diode denoting the cathode end.
You also always want to include a resistor with your LED wired to the cathode end of the LED. This will prevent the LED from burning out

You can follow Ohms Law (V = IR) to find the resistance needed. So we follow the formula R = (Vs - Vf) / If
R = Resistance in Ohms
Vs = Supply Voltage (ex. 3.3V)
Vf = Forward Voltage or Voltage Drop
If = LED Current Rating (ex. 20mA or 0.02A)

Or you can use a Online LED Calc http://bfy.tw/1qXp

Forward or drop voltage should be included in your LEDs data sheet or packaging. Some will give both a min and max values, use the average between these two.
Typically the forwards voltage goes by light temperature or color

The Supply voltage is the voltage your supplying from your board or batteries.

You can cheat with this guide if you do not know or can not find the forward voltage but this is not 100% accurate and is a generalization of what require for each color.
As LEDs from different manufacturers will have different specs with different forward voltages.

There also guides online to how to find your Forward voltage for a LED.

Once you find your resistance value needed know that you can go with a higher Ohm resistor with the only side effect being how bright the light is.
You never want to go with a lower Ohm resistor. So for example if you came up on the math needing a 43 ohm resistor but can’t find a 43 ohm resistor you can use the next closest rounded up like a 50 ohm resistor.

I come back and edit the guide later, if you see something wrong PM me so I can make any changes.


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Third party PS4 padhack options
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#2

This makes me smile to see as an electronics engineer. It is not a very much in depth documentation. Academically you would have started by defining what is a PN junction but i understand this is for the common user.


#3

Yes, I am skipping what a PN junction is and lot of the science involved in favor of making the guide for the Every-man and weekend DIY warrior. I notice quite a few beginner guides also skip some of the academics.
I also wanted to skip the math for LEDs, but I see it as a requirement. It’s also why I include talking about online LED calculators.

I am glad you approve as I lack formal training as a electronic engineer, my background more mechanic.


#4

Other online guides and sources for learning about diodes

https://learn.sparkfun.com/tutorials/diodes

http://www.talkingelectronics.com/projects/ElectronicsGuide/ElectronicsGuide.html

https://www.pc-control.co.uk/diodes.htm

http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/introduction-to-diodes-and-rectifiers/

YouTube Videos - Both of these going into the PN junction and the scientific theory involved
http://tinyurl.com/nkeh5ag -“How Does a Diode Work? Intro to Semiconductors (p-n Junctions in the Hood) | Doc Physics” - Doc Schuster
http://tinyurl.com/nwhslvh - “What’s a Diode? Here’s why diodes conduct one way but not the other | Doc Physics” - Doc Schuster (Part 2 of the first video)

http://tinyurl.com/oknlhr5 - “The PN Junction. How Diodes Work? (English version)” - fmgomezcampos


#5

well done, darksakul. i’d suggest making another thread like this that goes over multimeters. i sometimes see people recommending multimeters to diagnose problems with joysticks but they don’t explain how to use them. a tutorial showing how to probe, diagnose dead pcbs, and measure resistances could be very helpful to someone new to electronic circuitry.


#6

There are already some great multi-meter guides but maybe a breakdown on how they would apply in this context or the basics of what is typically used in regards to a multi-meters.


#7

Maybe some other time, I took hours to write that one post. Although I do understand the basics, my background is mechanics and not electronic engineering so there areas I gloss over, skipped or was still unsure about.
There many hours of fact checking, editing and trying to break everything down in laymen terms as much as possible.

With Multimeters I would have to do some camera work as well as it be more visual than the Diode guide.

There are several videos I did recommend in the past on you tube who all did a better How-to than me.


#8

Thanks for sharing this explanation with us. It will help to work with diodes and to make rectifiers. I want to know how i can detect the defective diode? Is there any method using multimeter or any direct observation is there? What is the method of their current calculation?

circuit board assembly


#9

Well if you are getting into rectifiers (especially bridge rectifiers). I wouldn’t use this guide as your only source of information as I just gloss over the topic. I would brush up with other online guides and videos, maybe get a book on the subject. This guide is just a basic introduction for the Home DIY crowd, particularly those who do controller mods for video games.

Assuming you have the typical normal diode, electricity goes in one way and not the other. Scroll up to How to “wire up” a diode? for more details.

Yes, some digital multimeters even have a Diode test.
Every method does the same thing, you are checking for current only goes one way and not the other.
Here is a video demonstrating this
https://www.youtube.com/watch?v=qSDRsz5-t7I

I don’t follow.


#10

Much thanks for the guide, very helpful to beginners like me!

You said not to worry about ampage, does that mean it doesn’t really matter how high or low we go? For mine i got 200mA but it would’ve been much easier to get lower ampage diodes than that from the shop i went to.


#11

Well for pad hacks it is not a big deal.
It matter if you are building more complex circuits.


#12

so a 10mA and 200mA would both work ok?


#13

I got to think about that one, maybe grab my multi meter and see what the actual amperage is on each signal line.

The safe bet would be using the 200mA diode. Honestly this was not a scenario I imaged.


#14

I picked up 200mA diodes, because in my other thread you’d mentioned that as “should pull no more than that” but would’ve been easier to buy smaller ones, but wasn’t sure if they’d work etc.


#15

How to wire up Player Indicator LEDs on a PS360+ (Universal Guide)

READ EVERYTHING BEFORE GOING FORWARDS WITH ANY MODS OR INSTALLATION.

Tools and materials
writing/note taking materials (pad and paper)
PC for viewing and/or printing the PDF
The PDF file (link given below)
2x AA battery holder and 2x AA batteries
Multimeter (or some other continuity tester)
Soldering Iron, solder
PS360+ board
JST cable for the LEDS (part of the JST alternate hook up kit for the PS360+)
(optional) fine point marker (like a sharpie)
(optional) Digital camera (for note taking)

You need to test what the polarity of each SMD LED, and how they are wired up on the board. I would recommend a battery holder for two AA batteries and using the wires as testing leads.
Now that you got the LED polarity, you should ether mark on the board or take a note on some paper which end of the LEDs is plus and minus. If you got a digital camera, take photos and annotate on the photo.

If you jump over to the hardware guide on the PS360+ , page 3 shows how the LEDs are to be wired for the PS360+.
http://akishop-customs.com/assets/img/bg/Files/PDF/PS360HardwareOverview.pdf

The LEDs wiring for the PS360+ have separate negatives for each LED and a common vcc or voltage source, when speaking just about LEDs its referred to a common anode.
The PS360+ was designed to best work with a Mad Catz TE, I can’t speak on how the LEDS are wired in other brand sticks. So I working here that your stick is also set up for common anode.

All that left is to find where is the common anode pin going out on your LED indicator/guide board and the 4 LED negative or cathode lines, this is where a multi meter would be handy.
Follow each LED trace. Confirm that the player indicator LEDs are common anode or common cathode. If the LEDS are Common Cathode this mod will not work (not with some more electronic “wizardry”).

If you are making a completely custon stick, wire up your LEDs for common anode, the forward voltage for your LEDs should be about 1.5 volts. You might have to install resistors to adjust (300 ohm is what Akishop recommends).

Also Make sure you desolder JP1 on the PS360+ PCB or risk damage to the PS360+.


#16

Okay with more people wanting to wire up their Player indicator lights, I going to briefly over that topic here.
As its an extension of the guide(s) on this thread.

All LEDs for player indicators are wired in one of two ways.
Common cathode or common anode.

If you scroll up to earlier parts of the guide you see Cathode is Positive and Anode Negative.

Now unlike the rest of your controller board/PCB for pad hacks, just because the controller board is wired for inputs as common ground does not mean your player indicator lights are the same.

Most typically on the Mad Catz TE, the PS360+, the Brooks Universal PCB the player indicator LEDs are wired as Common anode

http://i.imgur.com/5DLRNH7.png

that they all share the same voltage source.

That does not mean every board you run into will follow this example. You can have two Controller PCBs that do great for pad hacking and dual-modding and not share the same wiring scheme for the player indicator LEDs.

Keep in mind there could be boards with common cathode instead. On a guide board with no encoder chips, the LEDs can be rotated, on a actual controller board this is not that easy of a fix.
I assume that there is some electrical wizardry that can fix this but I can’t provide a schematic at this time. I will get back to this if I find something.


#17

I was literally just going to ask about this for the UFB. This “weekend DIY warrior” thanks you.


#18

It came up when someone else had the same question, so I felt I could add it to the thread.