Rangkaian Pengendali Motor DC model Darlington Rangkaian Pengendali Motor DC model Darlington

Kumpulan Skema Elektronika, A normal variable resistor cannot directly control the speed of a motor since motors draw large amounts of current which would burn out the potentiometer. Instead, the small amount of current that the potentiometer can pass can be amplified into order to run the motor. This amplification can be achieved using Darlington Pair of transistors.

Rangkaian Pengendali Motor DC

Pin-out BFY61 & TIP31C Transistor

The circuit above shows a linear potentiometer connected Between Vs and 0V Such That the voltage at its wiper terminal will of always be somewhere at or Between these two voltages. The small amount of current flowing out of the potentiometer's wiper is amplified by two transistors, connected together in a configuration known as a 'Darlington pair'. The current from the potentiometer is amplified by the first transistor, and then again by the second transistor, greatly Increasing the amount of current That cans be controlled by the potentiometer.

There are, however, a couple of disadvantages of this simple circuit. Firstly, about 0.7V is lost in EACH of the transistor, so the maximum voltage cans That ever be applied to the motor is Vs - 1.4V. Secondly, the transistors are not absolutely linear so the change in motor speed for a given rotation of the potentiometer will from some more subtle in the middle of its range. Because a motor is an inductive load, it will from Produce a 'back-emf' Could the which damage to the second transistor. The 1N4148 signal diode prevents this damage by shorting out the back-emf.

The power supply for this circuit should preferably be un-smoothed (i.e. directly from the power supply rectifier). This helps prevent the motor 'sticking' at low speeds. With the TIP31C transistor given, the maximum power supply voltage may be 60V and the maximum motor current consumption may be 3A.

Source: www.eleinmec.com

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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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Rangkaian Kontrol Kecepatan Wiper Mobil Rangkaian Kontrol Kecepatan Wiper Mobil

For some car wiper speed sometimes just made some speed so that less appropriate when we want a different speed, but for those of you who want a digital wiper speed controller you can also use this circuit to replace your old system.

Skema rangkaian kontrol kecepatan wiper mobil

This circuit comprises 2 timer NE555 ICs, one CD4017 decade counter, one TIP32 driver transistor, a 2N3055/ TIP3055 power transistor and A Few other discrete components. Timer IC1 is configured as a mono-stable multivibrator produces a pulse Pls Which one presses switch S1 momentarily. This pulse acts as a clock pulse for the decade counter (IC2) Which advances by one count on Each successive clock pulse or the push of switch S1. Ten presets (VR1 through VR10), for Different sets of values by trial and error, Are Used At The ten outputs of IC2. But since only one output of IC2 is high at a time, only one preset (selected at the output) effectively comes in series with resistors R4 and R5 timing connected in the circuit of timer IC3 Which functions in astable mode. As presets VR1 through VR10 are set for Different values, Different time periods (or frequencies) for astable multivibrator IC3 Can be selected. The output of IC3 is applied to the pnp driver transistor TIP32 for driving the final power transistor 2N3055 Which in turn drives the wiper motor at the selected sweep speed. The power supply for the wiper motor as well as the circuit is tapped from the vehicle s battery Itself. The duration of the monostable multivibrator IC1 is set for a period of nearly one second.

Source : www.electronic-circuits-diagrams.com

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Touch volume control circuit Touch volume control circuit

Touch controls are not only used to switch devices on or off. They can also be used to control different functions. One good example is the TV remote control. If it is very important to keep the activated functions for a long period of time, it is always better to use a digital memory system. However, if small drifts in the control status is acceptable, a simple analog design can be used to memorize the status.


The touch volume controller is one such analog memory touch control switch. The main function centers mostly on the IC1. It is an opamp configured as an integrator with a high impedance input. If sensor 1 is touched, the capacitor C2 charges through the skin resistance and voltage at the output of IC1 decreases linearly until it reaches zero volt. Touching the other sensor (sensor 2) will produce the opposite result: the voltage at the pin 6 of IC1 will increase linearly until it reaches the power supply level. The special function of this touch volume control circuit is that after moving your finger away from the sensor(s), the output voltage of IC1 stays at that level.
This voltage value is memorized by C2. This analog memory however has a problem in long time periods: The voltage value drifts away by 2 % per hour due to the unavoidable current leak in the capacitor. To improve this situation, it is highly recommended to put this circuit in a moisture proof box.
This touch volume controller circuit has a wide application range. It can be used in devices where a potentiometer can be controlled through voltage levels. The touch sensors can alse be replaced with conventional push button switches. The capactiors C1 and C4 are very important in the circuit: they prevent the IC1 from oscillating. Simultaneously closing both switches will not damage the circuit.

Touch volume control PCB layout

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Brightness Controller Circuit For Small Lamps and Leds Brightness Controller Circuit For Small Lamps and Leds

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Circuit diagram:

Brightness Controller Circuit For Small Lamps and Leds

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This device was designed on request; to control the light intensity of four filament lamps (i.e. a ring illuminator) powered by two AA or AAA batteries, for close-up pictures with a digital camera. Obviously it can be used in other ways, at anyone’s will.IC1 generates a 150Hz square wave having a variable duty-cycle. When the cursor of P1 is fully rotated towards D1, the output positive pulses appearing at pin 3 of IC1 are very narrow.
Bulb LP1, driven by Q1, is off as the voltage across its leads is too low. When the cursor of P1 is rotated towards R2, the output pulses increase in width, reaching their maximum amplitude when the potentiometer is rotated fully clockwise. In this way the bulb reaches its full brightness.

 Parts:
P1 = 470K
R1 = 10K
R2 = 47K
R3 = 1.5K
C1 = 22nF-63V
C2 = 100uF-25V
D1 = 1N4148
D2 = 1N4148
Q1 = BD681
B1 = 2xAA cells in series
IC1 = 7555 or TS555CN
LP1 = 1.5V 200mA Bulb
SW1 = SPST Switch

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Notes:

• LP1 can be one or more 1.5V bulbs wired in parallel. Maximum total output current allowed is about 1A.
• R2 limits the output voltage, measured across LP1 leads, to 1.5V. Its actual value is dependent on the total current drawn by the bulb(s) and should be set at full load in order to obtain about 1.5V across the bulb(s) leads when P1 is rotated fully clockwise.

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