How to build Traffic Light

This activity operates red, amber and blooming LEDs in the actual arrangement for a distinct UK cartage light. The time taken for the complete red - red & amber - blooming - amber arrangement can be assorted from about 7s to about 2½ account by adjusting the 1M preset. Some amber LEDs afford ablaze that is about red so you may adopt to use a chicken LED.

How to build Traffic Light

How to build Traffic Light Diagram

How to build Traffic Light DIagram

The 555 astable ambit provides alarm pulses for the 4017 adverse which has ten outputs (Q0 to Q9). Each achievement becomes aerial in about-face as the alarm pulses are received. Appropriate outputs are accumulated with diodes to accumulation the amber and blooming LEDs. The red LED is affiliated to the ÷10 achievement which is aerial for the aboriginal 5 counts (Q0-Q4 high), this saves application 5 diodes for red and simplifies the circuit.

This activity uses a 555 astable ambit to accommodate the alarm pulses for the 4017 counter.

Parts Required

resistors: 470 ×3, 22k, 100k

capacitors: 0.1µF, 1µF 16V radial, 10µF 16V radial

diodes: 1N4148 ×6

LEDs: red, amber (or yellow), green

1M preset, horizontal

555 timer IC, such as NE555

4017 adverse IC

DIL sockets for ICs: 8-pin, 16-pin

on/off switch

battery blow for 9V PP3

stripboard: 20 rows × 21 holes

Quiz Project Skema

This activity can be acclimated for a quiz with up to 4 contestants (or teams). Anniversary adversary has a activate push-switch and LED. Back a activate about-face is apprenticed it lights the agnate LED, sounds the bleeper and prevents the added

Quiz Project Skema

activate switches from alive - accordingly assuming which adversary was the aboriginal to columnist their switch. A displace push-switch (operated by the quizmaster) cancels the bleeper and switches off the LED so the ambit is accessible for the abutting question.

Take abundant affliction to align the genitalia accurately on the bunched stripboard layout. The LEDs are apparent army anon on the stripboard but you may adopt to arise them on a box application abbreviate wires. The activate switches charge continued cables of about 2 metres so they can be captivated by, or placed near, the contestants.

The ambit consists of four 555 timer bistables which are triggered or displace back their inputs are low. Their displace inputs are affiliated calm and operated by a distinct displace push-switch. The activate switches are affiliated to the bistable activate (pin 2) through a 0.1µF capacitor so that alone the antecedent columnist triggers the bistable; continuing to authority the about-face bankrupt will accept no effect. This is alleged bend triggering. Connecting the about-face anon to the bistable would anticipate the quizmaster from resetting the ambit until the activate about-face was appear and trials showed that abounding contestants kept the about-face apprenticed until asked to accord their answer! Back triggered the bistable achievement (pin 3) lights an LED and makes the 'trigger line' aerial - this prevents any added bistable actuality triggered and sounds the bleeper. A diode is acclimated to articulation the achievement to the activate line.

Parts Required

resistors: 470 ×4, 1k ×2, 10k ×8

capacitors: 0.1µF ×4, 1µF radial

diodes: 1N4148 ×4

LEDs: 1 anniversary red, green, chicken and blue, all 5mm diameter

555 timer ICs (such as NE555) ×4

DIL sockets for ICs: 8-pin ×4

bleeper acceptable for 9V

on/off switch

push about-face ×5

battery blow for 9V PP3

2-core cable such as 'figure 8', about 8 metres

stripboard: 10 rows × 50 holes

Dummy Alarm Project

This Dummy Anxiety activity makes an LED beam briefly already every 5 abnormal to imitate the indicator ablaze of a absolute alarm. The ambit is advised to use actual little accepted to prolong array activity so that it can be larboard on permanently. An on/off about-face is not included, but could be added if you wish.

Dummy Alarm Project

The 7555 timer IC acclimated is a low ability adaptation of the accepted 555 timer. A 'superbright' red LED is acclimated because this provides a ablaze beam with a low current. The LED is off for best of the time so the boilerplate absolute accepted for the ambit is beneath than 0.2mA. With this actual low accepted a set of 3 acrid AA beef should aftermost for several months, maybe as continued as a year.

The ambit will assignment with a accepted 555 timer IC (such as the accepted NE555) but this will access the boilerplate accepted to about 2mA and the array activity will be abundant shorter. You can use a greater accumulation voltage (15V maximum) for this ambit but the 1k resistor for the LED should be added to accumulate the LED accepted low at about 3mA. For archetype to use a 9V PP3 array change the 1k resistor to 3k3. Note that AA beef will aftermost best than a 9V PP3 battery.

This activity uses a 555 astable circuit.

Parts Required

resistors: 1k, 10k, 680k

capacitor: 10µF radial

LED: red superbright, 5mm diameter

7555 low ability timer IC

8-pin DIL atrium for IC

battery clip

4.5V array box for 3 AA cells

stripboard: 8 rows × 16 holes

Heart-shaped Badge Project

The badge consists of eight LEDs arranged in the shape of a heart. One LED is lit at a time and this 'chases' round the shape. It would be easy to adapt this project to create other shapes with the eight LEDs. This project uses a 555 astable circuit to provide the clock pulses for the 4017 counter.

Parts Required

Heart-shaped Badge Project

resistors: 2.2k, 47k, 270 ×8
capacitors: 0.1µF, 1µF 16V radial
red LEDs ×8
555 timer IC
4017 counter IC
DIL sockets for ICs: 8-pin, 16-pin
on/off switch
battery clip for 9V PP3
safety pin to attach badge
ribbon cable 9-way about 1 metre (to connect badge to main circuit)
stripboard: 16 rows × 19 holes for circuit, 10 rows × 9 holes for badge

Valentine Heart Project schema

Valentine Heart Project schema

This project flashes 18 LEDs at three different rates and you can use these to create an eye-catching Valentine Heart. The circuit is kept simple (and low cost) by using the 4060B IC which is a counter and oscillator (clock) in one package. The circuit requires a 9V supply, such as a PP3 battery. It will not work with lower voltages and a higher voltage will destroy the LEDs.

The preset variable resistor can be used to adjust the oscillator frequency and this determines the flash rate of the LEDs. The IC limits the current to and from its outputs so the LEDs can be safely connected without resistors in series to limit the current. The stripboard part of the circuit is easy to build but the wiring for the LEDs needs care so detailed instructions are provided below.

You can download our Valentine Heart template to print out and glue onto thick card, hardboard etc.

The Valentine Heart template is supplied as a PDF file. To view and print PDF files you need an Acrobat Reader which may be downloaded free for Windows, Mac, RISC OS, or UNIX/Linux computers. If you are not sure which type of computer you have it is probably Windows.

Warning!

Using a battery (or power supply) with a voltage higher than 9V will destroy the LEDs.

You can see from the circuit diagram (below) that 6 LEDs are connected in series between the +9V supply and 0V. Each LED requires about 2V across it to light, so using a voltage of about 12V (= 6 × 2V) or more will make the LEDs conduct directly, regardless of the 4060B IC. With no series resistor to limit the current this will destroy the LEDs.

Parts Required

resistors: 10k, 470k

preset: 47k (this could be 100k if necessary)

capacitor: 0.1µF

4060B IC

16-pin DIL socket for IC

LEDs × 18, 5mm diameter, red (or any mix of red, orange, yellow and green)

on/off switch

battery clip for 9V PP3

stripboard 13 rows × 18 holes

Stripboard Layout

Building the Circuit

Begin by soldering the components onto the stripboard as shown in the diagram above. Do not insert the 4060B IC at this stage.

Arranging the LEDs:

Cut out a suitable shape from stiff card (or similar material), such as the Valentine Heart template. Paint or colour the card at this stage if necessary.

Plan the layout of the 18 LEDs (suggested positions are marked on the template).

Drill 5mm holes for the LEDs - put the card on a piece of scrap wood to do this without damaging the card or the table.

Push LEDs into the holes, they should be a fairly tight fit and glue should not be necessary.

Label the LEDs D1 - D18 at random on the back of the card.

Wiring of the LEDs:

Use stranded wire for all the connections to the LEDs and solder all wires near to the LED body so the leads can be trimmed short later on.

The wire colours are suggested to avoid confusion but you can use other colours if you wish, the electricity won't mind! For example you could use red and black as suggested but substitute yellow and white for the blue and green suggested.

Cut all the LED short leads to be very short to make identification easier:

Connect RED wire to link up all the LONG leads of D1, D2 and D3.

Remember to solder wires near to the LED body so the long lead can be trimmed short later on.

Connect BLACK wire to link up all the SHORT leads of D16, D17 and D18.

Use 3 pieces of BLUE wire to connect:

D7 short - D10 long

D8 short - D11 long

D9 short - D12 long

Use 12 pieces of GREEN wire to connect:

D1 short - D4 long

D4 short - D7 long

D2 short - D5 long

D5 short - D8 long

D3 short - D6 long

D6 short - D9 long

D10 short - D13 long

D13 short - D16 long

D11 short - D14 long

D14 short - D17 long

D12 short - D15 long

D15 short - D18 long

Connect the RED wire from the circuit board to the RED wiring on the Valentine heart (connect it to any convenient point).

Connect the BLACK wire from the circuit board to the BLACK wiring on the Valentine heart (connect it to any convenient point).

Connect the 3 BLUE wires from the circuit board to each of the 3 BLUE wires on the Valentine heart, they may be connected in any order.

Carefully check all wiring.

Trim the long LED leads.

Plug the 4060B into its holder.

Connect a 9V battery and switch on.

Using a small screwdriver, adjust the 47k preset variable resistor to give a suitable flash rate for the LEDs.

Cara Kerja Solder

How to Solder

First a few safety precautions:

Never touch the element or tip of the soldering iron.

They are very hot (about 400°C) and will give you a nasty burn.

Cara Kerja Solder

Take great care to avoid touching the mains flex with the tip of the iron.

The iron should have a heatproof flex for extra protection. An ordinary plastic flex will melt immediately if touched by a hot iron and there is a serious risk of burns and electric shock.

Always return the soldering iron to its stand when not in use.

Never put it down on your workbench, even for a moment!

Work in a well-ventilated area.

The smoke formed as you melt solder is mostly from the flux and quite irritating. Avoid breathing it by keeping you head to the side of, not above, your work.

Wash your hands after using solder.

Solder contains lead which is a poisonous metal.

If you are unlucky (or careless!) enough to burn yourself please read the First Aid section.

Preparing the soldering iron:

Place the soldering iron in its stand and plug in.

The iron will take a few minutes to reach its operating temperature of about 400°C.

Dampen the sponge in the stand.

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment, then squeeze to remove excess water. It should be damp, not dripping wet.

Wait a few minutes for the soldering iron to warm up.

You can check if it is ready by trying to melt a little solder on the tip.

Wipe the tip of the iron on the damp sponge.

This will clean the tip.

Melt a little solder on the tip of the iron.

This is called 'tinning' and it will help the heat to flow from the iron's tip to the joint. It only needs to be done when you plug in the iron, and occasionally while soldering if you need to wipe the tip clean on the sponge.

You are now ready to start soldering:

Hold the soldering iron like a pen, near the base of the handle.

Imagine you are going to write your name! Remember to never touch the hot element or tip.

Touch the soldering iron onto the joint to be made.

Make sure it touches both the component lead and the track. Hold the tip there for a few seconds and...

Feed a little solder onto the joint.

It should flow smoothly onto the lead and track to form a volcano shape as shown in the diagram. Apply the solder to the joint, not the iron.

Remove the solder, then the iron, while keeping the joint still.

Allow the joint a few seconds to cool before you move the circuit board.

Inspect the joint closely.

It should look shiny and have a 'volcano' shape. If not, you will need to reheat it and feed in a little more solder. This time ensure that both the lead and track are heated fully before applying solder.

555 and 556 Timer Circuits

The 8-pin 555 timer must be one of the most useful ICs ever made and it is used in many projects. With just a few external components it can be used to build many circuits, not all of them involve timing!

A popular version is the NE555 and this is suitable in most cases where a '555 timer' is specified. The 556 is a dual version of the 555 housed in a 14-pin package, the two timers (A and B) share the same power supply pins. The circuit diagrams on this page show a 555, but they could all be adapted to use one half of a 556.

Low power versions of the 555 are made, such as the ICM7555, but these should only be used when specified (to increase battery life) because their maximum output current of about 20mA (with a 9V supply) is too low for many standard 555 circuits. The ICM7555 has the same pin arrangement as a standard 555.

The circuit symbol for a 555 (and 556) is a box with the pins arranged to suit the circuit diagram: for example 555 pin 8 at the top for the +Vs supply, 555 pin 3 output on the right. Usually just the pin numbers are used and they are not labelled with their function.

The 555 and 556 can be used with a supply voltage (Vs) in the range 4.5 to 15V (18V absolute maximum).

Standard 555 and 556 ICs create a significant 'glitch' on the supply when their output changes state. This is rarely a problem in simple circuits with no other ICs, but in more complex circuits a smoothing capacitor (eg 100µF) should be connected across the +Vs and 0V supply near the 555 or 556.

The input and output pin functions are described briefly below and there are fuller explanations covering the various circuits:

Astable - producing a square wave

Monostable - producing a single pulse when triggered

Bistable - a simple memory which can be set and reset

Buffer - an inverting buffer (Schmitt trigger)

Datasheets are available from:

DatasheetArchive.com

Datasheets.org.uk

DatasheetCatalog.com