Adjustable 1-10 Minute Timer Project

A kit for this activity is accessible from RSH Electronics.

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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

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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

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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

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

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Rangkaian preampmic microphone

It is using a transistor type of low noise types: BC 650 C, but it was hard to find transistors can be replaced degan 109 BC which is just as good. EMC electret condenser mic or in which there is a very sensitive micriphone element and an internal FET preamp circuit, so any 'voltage to the EMC is between 20-10 volts, for that we can love resistor 1 K-10 K ohms for the EMS mesuplay.

Rangkaian preampmic microphone

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