Rangkaian Timer On-Off 24 Jam Rangkaian Timer On-Off 24 Jam

Timer On-off 24 Jam. This is a circuits are multi-range timers offering periods of up to 24 hours and beyond. This circuit can be used as repeating timers - or as single-shot timers

Skema Rangkaian On/Off 24 Hours Timer

The Cmos 4060 is a 14-bit binary counter. However - only ten of those bits are connected to output pins. The 4060 also has two inverters - connected in series across pins 11, 10 & 9. Together with R3, R4, R5 and C3 - they form a simple oscillator.

While the oscillator is running - the 14-bit counter counts the number of oscillations - and the state of the count is reflected in the output pins. By adjusting R4 you can alter the frequency of the oscillator. So you can control the speed at which the count progresses. In other words - you can decide how long it will take for any given output pin to go high.

When that pin goes high - it switches the transistor - and the transistor in turn operates the relay. In single-shot mode - the output pin does a second job. It uses D1 to disable the oscillator - so the count stops with the output pin high.

If you want to use the timer in repeating mode - simply leave out D1. The count will carry on indefinitely. And the output pin will continue to switch the transistor on and off - at the same regular time intervals.

Note:

• Using "Trial and Error" to set a long time period would be very tedious. A better solution is to use the Setup tables provided - and calculate the time required for Pin 7 to go high. For example, if you want a period of 9 Hours - the Range table shows that you can use the output at Pin 2. You need Pin 2 to go high after 9 x 60 x 60 = 32 400 seconds. The Setup table tells you to divide this by 512 - giving about 63 seconds. Adjust R4 so that the Yellow LED lights 63 seconds after power is applied. This will give an output at Pin 2 after about 9 Hours.
• Ideally C3 should be non-polarized - but a regular electrolytic will work - provided it doesn't leak too badly in the reverse direction. Alternatively - you can simulate a non-polarized 10uF capacitor by connecting two 22uF capacitors back to back
• The timers were designed for a 12-volt supply. However - provided a suitable relay is used - both circuits will work at anything from 5 to 15-volts. Applying power starts the timer. And it can be reset at any time by a brief interruption of the power supply.

Sorcer: http://www.zen22142.zen.co.uk/

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Multivibrator Astable Menggunakan IC 555 Multivibrator Astable Menggunakan IC 555

Multivibrator is an electronic circuit that at a certain time only one of two output voltage levels, except during the transition period. The transition (switching) between the two levels of output voltage occurs quickly. Two state level of the multivibrator output voltage, which is stable and Quasistable.

Astable multivibrator is called when the output voltage levels generated by the multivibrator circuit is quasistable. The circuit will only change the state of the output voltage level between the 2 conditions, each state has a fixed period. Multivibrator circuit will work independently and no longer need a trigger. Period of time each output voltage level is determined by the components making up the circuit.

The picture above is the astable multivibrator circuit. This circuit will work when the voltage applied to Vcc ration and ground her. This circuit has two conditions are always changing with time. Because changing the type is known as astable multivibrator. With constant changes of 0 and 1, then the multivibrator is also called a bistable multivibrator (multivibrator which has two stable state of 0 and 1).


This change in cycle length can be calculated using the following equation:

Period = t1 + t2
t1 = 0.7 x (RA + RB) XC
t2 = 0.7 xRBxC.

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Rangkaian Multivibrator Monostable IC 555 Rangkaian Multivibrator Monostable IC 555

Multivibrator Monostable IC 555

Rangkaian Multivibrator Monostable IC 555 is a pulse generator circuit in which the duration of the pulse is determined by the R-C connected to IC 555 timer. In such a vibrator, one state of output is stable while the other is quasi-stable (unstable). For auto-triggering of output from quasi-stable state to stable state energy is stored by an externally connected capaci tor C to a reference
level. The time taken in storage determines the pulse width. The transition of output from stable state to quasi-stable state is accom­plished by external triggering.

Capacitor C has to charge through resistance RA. The larger the time constant RAC, the longer it takes for the capacitor voltage to reach +2/3VCC. In other words, the RC time constant controls the width of the output pulse. The time during which the timer output remains high is given as

tp = 1.0986 RAC

where RA is in ohms and C is in farads. The above relation is derived as below. Voltage across the capacitor at any instant during charging period is given as

vc = VCC (1- e-t/RAC)

Substituting vc = 2/3 VCC in above equation we get the time taken by the capacitor to charge from 0 to +2/3VCC.

So +2/3VCC. = VCC. (1 – e-t/RAC) or t – RAC loge 3 = 1.0986 RAC

So pulse width, tP = 1.0986 RAC s 1.1 RAC

The pulse width of the circuit may range from micro-seconds to many seconds. This circuit is widely used in industry for many different timing applications.

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