Light-sensitive Alarm Project

The ambit detects a abrupt adumbration falling on the light-sensor and sounds the bleeper back this happens. The ambit will not acknowledge to bit-by-bit changes in accuracy to abstain apocryphal alarms. The bleeper sounds for alone a abbreviate time to anticipate the array active flat. Normal lighting can be used, but the ambit will assignment

best if a axle of ablaze is abiding to abatement on the light-sensor. Breaking this axle will again account the bleeper to sound. The ablaze sensor is an LDR (light-dependant resistor), this has a low attrition in ablaze ablaze and a aerial attrition in dim light.

Light-sensitive Alarm Project

The light-sensitivity of the ambit can be adapted by capricious the 100k preset.

The breadth of beep can be assorted from 0.5 to 10 abnormal application the 1M preset.

Using the 7555 low-power timer ensures that the ambit draws actual little accepted (about 0.5mA) except for the abbreviate times back the bleeper is aural (this uses about 7mA). If the ambit is switched on continuously an acrid PP3 9V array should aftermost about a month, but for best activity (about 6 months) you can use a backpack of 6 AA acrid batteries.

This activity uses an edge-triggered 555 monostable circuit.

Parts Required

resistors: 10k, 47k, 1M ×3

presets: 100k, 1M

capacitors: 0.01µF, 0.1µF, 10µF 25V radial

transistor: BC108 (or equivalent)

7555 low-power timer IC

8-pin DIL atrium for IC

LDR (light-dependant resistor) blazon ORP12

bleeper 9-12V

on/off switch

battery blow for 9V PP3

stripboard 12 rows × 25 holes

Adjustable 1-10 Minute Timer Project

A kit for this activity is accessible from RSH Electronics.

Download PDF adaptation of this folio

The ambit starts timing back switched on. The blooming LED lights to appearance that timing is in progress. Back the time aeon is over the blooming LED turns off, the red LED turns on and the bleeper sounds.

Adjustable 1-10 Minute Timer Project

The time aeon is set by adjusting the capricious resistor. It can be adapted from 1 to 10 account (approximately) with the genitalia apparent in the diagram. You can mark the times on a calibration fatigued on the box.

Please agenda that the ambit of time periods is alone approximate. With absolute apparatus the best time aeon should be 4½ minutes, but this is about continued to about 10 account because the 220µF timing capacitor boring leaks charge. This is a botheration with all electrolytic capacitors, but some aperture added than others. In accession the absolute amount of electrolytic capacitors can alter by as abundant as ±30% of their rated value.

This activity uses a power-on triggered 555 monostable circuit.

Parts Required

resistors: 470, 33k, 100k

variable resistor: 1M

capacitors: 0.1µF, 220µF 16V radial

LEDs: red, green

bleeper 9-12V

555 timer IC

8-pin DIL atrium for IC

on/off switch

battery blow for 9V PP3

stripboard 10 rows × 22 holes

Simple Electronic Lock Project

There are six (or more) advance switches. To 'unlock' you charge columnist all the actual ones at the aforementioned time, but not columnist any of the abolish switches. Pressing aloof one abolish about-face will anticipate the ambit unlocking. Back the ambit unlocks it absolutely aloof turns on an LED for about one second, but it is advised to be acclimatized to about-face on a broadcast which could be acclimated to about-face on addition circuit.

Please Note: This ambit aloof turns on an LED for about one additional back the actual switches are pressed. It does not absolutely lock or alleviate anything!

This activity uses a 555 monostable circuit.

Simple Electronic Lock Project

Parts Required

resistors: 470, 100k ×2, 1M

capacitors: 0.1µF, 1µF 16V radial

red LED

555 timer IC

8-pin DIL atrium for IC

on/off switch

push-switch ×6 (or more)

battery blow for 9V PP3

stripboard 12 rows × 25 holes

Flashing LED Project

LED stands for Light Emitting Diode

A kit for this activity is accessible from RSH Electronics.

Download PDF adaptation of this folio

Flashing LED Project

This activity is advised as an addition to soldering, anecdotic accepted components, application the resistor colour cipher and agreement apparatus accurately on stripboard. The LED flashes at about 3Hz (3 flashes per second). This activity uses a 555 astable circuit.

Parts Required

resistors: 470, 1k, 220k

capacitor: 1µF 16V radial

red LED (or orange, chicken or blooming if you prefer!)

555 timer IC

8-pin IC holder (a 'DIL socket') for the 555 IC

battery blow for 9V PP3

stripboard: 6 rows × 21 holes

Instructions

Solder the 8-pin IC holder in the actual abode on the stripboard.

Break the 4 advance beneath the IC holder with a clue cutter tool. You can acquiesce added holes if your allotment of stripboard is ample enough.

Simple Component and Continuity Tester

This simple activity may be acclimated for testing components, as able-bodied as blockage ambit lath tracks, affairs and access for chain (conduction). It tries to canyon a baby accepted through the account actuality activated and the LED will ablaze brightly, dimly or not at all according to the attrition of the item:

LED ablaze agency the attrition is low, beneath than about 1k

Simple Component and Continuity Tester

LED dim agency the attrition is medium, a few k

LED off agency the attrition is high, added than about 10k

When not in use the 9V PP3 array should be unclipped or the crocodile clips absorbed to a allotment of agenda or artificial to anticipate them touching. You could add an on-off about-face in the red wire from the array blow and this may be the best advantage if you arise the simple tester in a box.

Parts Required

If you anticipate this activity is too simple to be useful, amuse see the table of apparatus which it can be acclimated to analysis and anticipate again!

resistor: 390

red LED 5mm diameter, accepted type

battery blow for 9V PP3

crocodile clips: miniature red and black

stripboard: 5 rows × 7 holes

Stripboard Layout

Testing stripboard, PCB tracks, affairs and connections

Circuit diagram

Connect a crocodile blow on anniversary ancillary of the doubtable fault:

LED ablaze agency there is a connection.

LED off agency there is no connection.

If you are testing a stripboard or PCB which has apparatus anchored in place, beware of accessible access via the apparatus and acquiesce for this back interpreting the results.

Stripboard circuits can ache from two accepted problems: adhesive bridging amid adjoining advance authoritative a affiliation area there should be none, and advance burst with a clue cutter which accept an about airy cilia of chestnut administering beyond the break.

If a PCB has categorical ailing the advance may be actual attenuate in places or there may be traces of chestnut bridging amid adjoining tracks.

Wires and access may be arrested for chain (conduction).

Model Lighthouse Project

This activity was advised for a archetypal alarm to beam a lamp in a simple sequence: two flashes of 2s with a abbreviate gap of 1s, followed by a best gap of 5s afore repeating the sequence.The 555 timer is affiliated as an astable

Model Lighthouse Project

to accommodate alarm pulses for the 4017 counter. The 4017 has ten outputs (Q0 to Q9) and anniversary one becomes aerial ('on') in about-face as the alarm pulses are received. Outputs Q0, Q1, Q3 and Q4 are accumulated with diodes to aftermath the beam sequence. A transistor amplifies the accepted to ability the lamp, or LED if you adopt (a 470 LED resistor is included on the stripboard layout). The 1M preset controls the time aeon (T) of the 555 astable from about 0.1s to 1.5s, for archetype set T = 1s.

For a altered beam arrangement affix the diodes to amalgamate altered 4017 outputs (Q0-Q9). If the abounding calculation from 0 to 9 is not appropriate one of outputs can be affiliated to the displace ascribe (pin 15). For archetype abutting Q8 (pin 9) to displace (pin 15) reduces the continued gap at the end of the arrangement to 3s (with T=1s).

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

For advice about lighthouses in the UK appointment www.trinityhouse.co.uk

Parts Required

resistors: 470, 2k2, 22k, 100k

capacitors: 0.1µF, 1µF 16V radial

diodes: 1N4148 ×4

transistor: BC108 (or equivalent)

1M preset, horizontal

6V 60mA MES lamp

MES lampholder

555 timer IC, such as NE555

4017 adverse IC

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

on/off switch

battery clip

9V array box for 6 AA cells

stripboard: 19 rows × 21 holes

Dice Project

Press the advance about-face to 'throw' the dice: this makes the ambit rapidly aeon through the dice numbers so that an finer accidental dice cardinal is displayed by the LEDs back the advance about-face is released.

Dice Project

Drill seven 5mm holes in a dice arrangement to arise the LEDs on a console such as a artificial box lid or area of attenuate plywood. They should be a bound fit but a little cement can be activated from the base if necessary.

The 555 astable ambit provides alarm pulses at about 5kHz for the 4017 adverse which has ten outputs (Q0 to Q9). Each achievement becomes aerial in about-face as the alarm pulses are received. Only six counts (Q0-Q5) are bare so Q6 is affiliated to reset. Appropriate outputs are accumulated with diodes to accumulation the LEDs: for archetype Q1, Q3 and Q5 are accumulated for LED A.

The dice arrangement has been started at 2 so the ÷10 achievement can be acclimated for LEDs B1 and B2, this saves diodes and simplifies the circuit. Pressing the advance about-face makes the attenuate ascribe low so that counting occurs.

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

Parts Required

resistors: 330 ×3, 470, 10k ×3

capacitors: 0.01µF, 0.1µF

diodes: 1N4148 ×6

LEDs: red 5mm bore ×7

555 timer IC, such as NE555

4017 adverse IC

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

on/off switch

push switch

battery blow for 9V PP3

stripboard: 20 rows × 22 holes