How to make a tester for any LED
This is a very simple but useful LED tester that lets you test, compare and check the color of just about any two pin LED.
To make it you will need the following:-
A PP3 battery connector.
A 470 ohm resistor.
A bit of heat shrink sleeve to cover the resistor.
A two pin Molex style 0.1" (2.54mm) pitch miniature socket.
Two contacts for the socket.
A PP3 9V battery. Alkaline preferred.
The main part of this instructable is a cheap and common PP3 battery connector used to connect to the small rectangular 9V batteries.
The tester needs a resistor to limit the current through the LED. I generally use a 470 ohm resistor which has the color code:-
Yellow, purple, brown and gold. (For a standard four band resistor.)
To put the resistor in line the red lead is cut about 2" (50mm) from the end and the wire stripped, the resistor soldered in and a piece of heat-shrink tubing shrunk over the resistor and solder connections to protect them.
The three steps are shown in the picture.
This project uses an ordinary two pin Molex style socket to connect to the LED. To use the socket you need to crimp or solder wires to the contacts before they are pressed into an empty socket shell. The crimping tool for these contacts is quite expensive, so you may find it cheaper to just solder the wires to the contacts as shown.
Since the red lead may be slightly longer with the inline resistor, it may be a good idea to trim the red and black leads down to the same length.
The easiest way to solder these contacts is to tin both the contact and wire with a touch of solder and then touch them both together and reflow the solder with your soldering iron.
Once both the contacts have been soldered to the wires they are pushed into the housing so that their little latches click into place in the matching slots in the socket.
To make polarity identification easier it's useful to use a red and black marker pen to mark the front of the socket as shown. Give the two wires a quick twist for neatness and snap your new tester onto a PP3 battery and you now have an LED tester that will test your LEDs with about 10 to 15mA when their leads are pushed into the socket.
Now in this step we just need to glue the battery connector to the other side of the PCB. Use a hot glue gun or instant adhesive glue.
Take a look at the above images and glue it perfectly.
Here i used an instant adhesive glue in this project.
What do you get for the geek who has everything and likes LEDs? A tricked-out LED tester, naturally. Dave Cook's deluxe model sports an LCD screen and two adjustable values: desired current and supply voltage. Dial these in, plug in your LED, and the tiny electronic brain inside figures out the resistor value that you need. How easy is that?
An LED tester can be as easy as a constant-current power supply, and in fact that's what [Dave]'s first LED tester was, in essence. Set an LM317 circuit up to output 10mA, say, and you can safely test out about any LED. Read off the operating voltage, subtract that from the supply voltage, then divide by your desired current to figure out the required resistor. It only takes a few seconds, but that's a few seconds too many!
The new device does the math for you by adding an AVR ATtiny84 into the mix. The microcontroller reads the voltage that the constant current supply requires, does the above-mentioned subtraction and division, and displays the needed resistor. So simple. And as he demonstrates in the video below, it does double-duty as a diode tester.
This is a great beginner's project, and it introduces a bunch of fundamental ideas: reading the ADC, writing to an LED screen, building a constant current circuit, etc. And at the end, you have a useful tool. This would make a great kit!
Please follow the simple steps below to make your own LED tester to check the LED bulb polarities and also check whether a LED bulb is defective or not.
Step 1. First of all, you will need a 9 Volt battery and two 5 inches long wires and black tape. (Please only use this 9V battery, never use any battery that exceeds 12V which would potentially damage the LED and also do not use a battery under 9V which is not big enough to light up the LED)
Step 2. Strip some plastic sheathing off of both ends of the wires and hook the wires to the battery's positive and negative. (Make sure to hook the red wire to the battery positive terminal and the black wire to the battery negative terminal)
Step 3. Use black tape to cover the +/- terminals up.
Step 4. Now you have made your own LED tester. You can tap the Red and Black wires to the LED bulb to check which side of the LED bulb is positive (polarity) and also to see whether a LED bulb is defective ( Note: if a LED bulb does not light up at the first time , please flip the two wires around and try again)
How to make a tester for any LED
This is a very simple but useful LED tester that lets you test, compare and check the color of just about any two pin LED.
To make it you will need the following:-
A PP3 battery connector.
A 470 ohm resistor.
A bit of heat shrink sleeve to cover the resistor.
A two pin Molex style 0.1" (2.54mm) pitch miniature socket.
Two contacts for the socket.
A PP3 9V battery. Alkaline preferred.
The main part of this instructable is a cheap and common PP3 battery connector used to connect to the small rectangular 9V batteries.
The tester needs a resistor to limit the current through the LED. I generally use a 470 ohm resistor which has the color code:-
Yellow, purple, brown and gold. (For a standard four band resistor.)
To put the resistor in line the red lead is cut about 2" (50mm) from the end and the wire stripped, the resistor soldered in and a piece of heat-shrink tubing shrunk over the resistor and solder connections to protect them.
The three steps are shown in the picture.
This project uses an ordinary two pin Molex style socket to connect to the LED. To use the socket you need to crimp or solder wires to the contacts before they are pressed into an empty socket shell. The crimping tool for these contacts is quite expensive, so you may find it cheaper to just solder the wires to the contacts as shown.
Since the red lead may be slightly longer with the inline resistor, it may be a good idea to trim the red and black leads down to the same length.
The easiest way to solder these contacts is to tin both the contact and wire with a touch of solder and then touch them both together and reflow the solder with your soldering iron.
Once both the contacts have been soldered to the wires they are pushed into the housing so that their little latches click into place in the matching slots in the socket.
To make polarity identification easier it's useful to use a red and black marker pen to mark the front of the socket as shown. Give the two wires a quick twist for neatness and snap your new tester onto a PP3 battery and you now have an LED tester that will test your LEDs with about 10 to 15mA when their leads are pushed into the socket.
Now in this step we just need to glue the battery connector to the other side of the PCB. Use a hot glue gun or instant adhesive glue.
Take a look at the above images and glue it perfectly.
Here i used an instant adhesive glue in this project.
What do you get for the geek who has everything and likes LEDs? A tricked-out LED tester, naturally. Dave Cook's deluxe model sports an LCD screen and two adjustable values: desired current and supply voltage. Dial these in, plug in your LED, and the tiny electronic brain inside figures out the resistor value that you need. How easy is that?
An LED tester can be as easy as a constant-current power supply, and in fact that's what [Dave]'s first LED tester was, in essence. Set an LM317 circuit up to output 10mA, say, and you can safely test out about any LED. Read off the operating voltage, subtract that from the supply voltage, then divide by your desired current to figure out the required resistor. It only takes a few seconds, but that's a few seconds too many!
The new device does the math for you by adding an AVR ATtiny84 into the mix. The microcontroller reads the voltage that the constant current supply requires, does the above-mentioned subtraction and division, and displays the needed resistor. So simple. And as he demonstrates in the video below, it does double-duty as a diode tester.
This is a great beginner's project, and it introduces a bunch of fundamental ideas: reading the ADC, writing to an LED screen, building a constant current circuit, etc. And at the end, you have a useful tool. This would make a great kit!
Please follow the simple steps below to make your own LED tester to check the LED bulb polarities and also check whether a LED bulb is defective or not.
Step 1. First of all, you will need a 9 Volt battery and two 5 inches long wires and black tape. (Please only use this 9V battery, never use any battery that exceeds 12V which would potentially damage the LED and also do not use a battery under 9V which is not big enough to light up the LED)
Step 2. Strip some plastic sheathing off of both ends of the wires and hook the wires to the battery's positive and negative. (Make sure to hook the red wire to the battery positive terminal and the black wire to the battery negative terminal)
Step 3. Use black tape to cover the +/- terminals up.
Step 4. Now you have made your own LED tester. You can tap the Red and Black wires to the LED bulb to check which side of the LED bulb is positive (polarity) and also to see whether a LED bulb is defective ( Note: if a LED bulb does not light up at the first time , please flip the two wires around and try again)
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