Tsukure Mad Labs 1 Watt LED Dimmer
LEDs can be dimmed in two ways; analog and pulse-width modulation (PWM) dimming. Analog dimming changes LED light output by simply adjusting the DC current in the circuit to the LED, while PWM dimming achieves the same effect by varying the duty cycle of a constant current, effectively change the average current supplied to the LED.
Analog dimming is not suitable for many applications as dimming accuracy is reduced by roughly 20% at 10:1 brightness. It also skews colour contrast. PMW on the other hand can produce 3000:1 and higher dimming ratios at (100Hz) without any significant loss of acurate and no change in LED colour.
This project explores one method of dimming LEDs using the reliable 555 timer chip.
Components used in this module...
Find out more about the components used in this STEM Module.
Let's Get Started!
Below you will find a list of bits to gather before hand, followed by a detailed schematic. Using a breadboard lay out the components and connect them together as shown. Alternatively you can purchase this module from our shop and simply solder the components in the places indicated on the quality assured printed circuit boards provided.
What You Need...
|1||103 (10nF / 0.01uF)||Capacitor (Ceramic)|
|1||8-Pin||IC Socket (DIP / DIL)|
|1||555 Timer||Integrated Circuit (IC)|
|1||1 Watt / 3.5V (White)||LED|
|1||Tsukure Mad Labs - 1 Watt LED Dimmer||PCB|
[ Brown, Black, Black, Black ]
|Resistor (0.25 Watt)|
[ Brown, Black, Black, Brown ]
|Resistor (0.25 Watt)|
|1||10K||Resistor (Potentiometer / Variable)|
NB: Any resistor colour codes specified relate to 5 band resistor codes, the 5th band has not been shown intentionally. The 5th band indicates the resistor tolerence, we use only the highest tolerence resistors in our products.
Take a Closer Look!
Let's Get Building!
We to build, so let's get to it! Gather your components as specified in the components list above, or simply order one of our project packs and tip the contents out onto your table or desk.
Solder station warmed up! Snips at the ready! Here we go!
Step 1) Getting Started
Before we begin placing components and soldering we should first place your components in a small tub so that they don't roll off your table or get lost.
Lay the PCB out infront of you and take a close look at all the components we will be using.
Furher explanations and detailed specifications of all these components can be found in our Wiki.
Step 2) Be a Darlington!
The Darlington Transistor can not only help to power the dimming circuitry in this project but it can also be used to control DC Motor speeds.
This particular transistor looks much like a Voltage Regulator but works very differently so don't get them confused!
In order to place the darlington transistor you will need to bend the trhee pins at 90 degrees to the back before inserting into the PCB and soldering.
Step 3) Chips!
A 555 Timer Chip is the most important part of this circuit, bar the power. It will be responsible for providing the pulses that will provide the average voltage source used to control the brightness of the LED. With our kits we have provided both a 555 Timer chip and an IC Socket also known as a DIL or DIP socket.
Insert the socket onto the board and solder ensuring the small semi-cirle cutout lines on the socket with the same symbol on the PCB. Once soldered you will be able to reuse the timer chip in other projects!
Step 4) Now for the Wee Orange Thing!
The tiny orange component is a capacitor, this particular capacitor is non-poloroised but polorised capacitors are also available although not required in this project. It does not metter which way this component is inserted into the PCB.
Either bend the legs back slightly to hold in place before soldering or use some BluTack.
Step 5) This Way, That Way!
Diodes are designed to mostly prevent the back-flow of current throughout a circuit. Often used to ensure an AC circuit is "converted" to DC by way of "rectification" or as a method of preventing terminal polorisation due to accidentally crossing power wires.
The diodes we are using in this project are known as "Zener" diodes and are commonly found in audio and low-voltage projects. When placing these components on the PCB ensure the thick black line alines with the indicated marking on the PCB. Getting this the wrong way round will prevent your circuit from working as current will not be able to get to where it is supposed to go.
Step 6) Current Limiting
Current limiting is the generl purpose of a resistor. Resistors come in many values and sizes. This project uses 2 different values which can be easily assertained by the different colours shown in the coloured bands printed on the surface of the resistor.
Pay careful attention to which resistor is placed where as incorrect placement could result in damage to your circuit.
If you are uncertain which resistor is which value we have provided the color codes in the component list accompanying this project.
Step 7) Potentially Dimmer!
Potentiometers (Variable Resistors) are variable resistors or resistors that have a variable resistance. Glad we cleared that up. This component will allow the user to interact with the project by provinding a rotational brightness selection interface. A BIG KNOB!
Its relatively obvious how this component should be homed on the PCB.
Step 8) Power!
We will be using a 9V battery to power this project. Take the blue connector block, place it on the board and solder it in place ensuring the opening where you will connect the battery connector and battery are facing outwards. Next solder the white JST wire to the on/off switch provided and place the white JST socket on the PCB.
Solder the switch connector in place and connect the assemble switch circuit to the PCB.
DO NOT CONNECT THE BATTERY JUST YET!
Step 9) The the Light Shine!
Our final step is to connect the 1 Watt LED to the PCB. The LED we have provided with our kits has a red wire and a black wire. If you are sourcing your own components you will need to assertain which is the anode and which is the cathode. Either way, the cathode or "black" wire must be place through the hole indicated by the flat side of the PCB printed symbol and the "red" wire or anode must be solder to the top hole (the hole nearest the resistors).
Getting this wrong will mean your light won't shine :(
With the LED firm,ly soldered in place, you can connect you battery, switch the switch and brighten someones life :)
Or dim it depending on the mood!
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