Menguji Dioda Menggunakan Multi Meter

Menguji Dioda Menggunakan Multi Meter

In the diode consists of cathode and anode, and this is given one mark. Then the steps using a multimeter diode test is as follows:

1. Turn the switch on the Ohm, let R x 1K
2. Investigators Attach the red to the cathode (+) and black Investigators at the anode (-) diode
3. If the needle moves multimeter that is good, but if the needle does not move means diodes have been broken or damaged
4. Then a black investigator then attached to the cathode (+) and red pencolok attached to the anode (-). When the needle multimeter silent, means the diode is in good condition but if the move means that the diode has been leaked (damaged)

About Diode

A diode is the basic electronic component. It’s property is that it can conduct only in one direction. A diode can be made by joining a p type semiconductor and an n type semiconductor. At the junction point there will be a voltage drop due to the migration of carriers. The voltage at this barrier is known as barrier potential. Ideally the barrier potential is zero. But in practical case there will be a drop of 0.7 Volts.

When the P side of diode is connected to the positive of power supply and N region is connected to the negative of supply, the diode is said to be in forward biased condition. At this condition, if the applied voltage is greater than the barrier potential of the diode, it starts conduction. After the diode is arrived in the conduction mode, the drop across it remains at 0.7 V. After the conduction starts, if the voltage is increased further, current trough it increases linearly with voltage.

When the supply voltage is reversed the diode is said to be in reverse biased condition. Here there is no conduction at lower voltage values .If we increase the voltage value further ,it is observed that at a voltage the current sharply increases due to the breakdown of the P-N junction. This damages the device.

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Antena Pemancar Radio FM

The antenna serves to radiate signals and radio wave radiation. Antenna generally divided into two by the beam, ie

Omnidirectional (all directions). This antenna radiates radio waves strong kesegala same direction.

bidirectional (both directions). This antenna radiates radio waves as strong to just two directions. The two parameters that need to be considered on an antenna is the polarization and penguatannya. Simply put, an antenna has a vertical polarization if the antenna is placed in a position perpendicular to the earth. Antenna with vertical polarization will produce radio waves with vertical polarization, too. In addition to vertical, there are also berpolarisasi horizontal antenna, the antenna plays when the field parallel to the earth.

Gambar antena FM Omnidirectional

One important factor in the FM antenna system installation is the antenna height. In the VHF band, provided that communication can take place is a LOS (Line Of Sight). So ideally communications on VHF, the antenna receiver and transmitter both have seen each other. So in between there must be no objects that can absorb radio energy.

So that radio amateurs in the VHF band is often stated that a better antenna has a small gain but higher than the antenna mounted with a large gain but low installed.

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Rangkaian Penala Antena

This is a series of antenna-tuning circuit or circuits for transmitting antenna placement SW 3-30 MHz wave / short wave 3-30 Mhz. If the placement is just right then the maximum energy from the transmitter will send out all the antenna through sehinnga nothing is wasted. To get a clear picture of the circuit is click on the picture below.

Skema Rangkaian Penala Antena

This transmacth circuit function is to locate an appropriate impedance between the transmitting antenna that occurred in the ratio 1:1 SWR reading it, because in this placement is associated with a series of SWR / standing wave ratio. Thus the purpose of 1:1 is the one that came out was also one emitted by the antenna instead of just half saja.Impedansinya generally is 50 Ohm. With this circuit the maximum power that can pass this circuit is 50 Watt.


About SWR meter

The SWR meter or VSWR (voltage standing wave ratio) meter measures the standing wave ratio in a transmission line. This is an item of radio equipment used to check the quality of the match between the antenna and the transmission line.

SWR Meter Installation

SWR Meter Pic

The VSWR meter should be connected in the line as close as possible to the antenna. This is because all practical transmission lines have a certain amount of loss, causing the reflected power to be attenuated as it travels back along the cable, and producing an artificially low VSWR reading on the meter.

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Pengatur Kecepatan Motor Menggunakan PWM

So-called PWM or Pulse Modulation Witdh is a technique often used to control a load, for example, is the DC motor speed control, PWM techniques are often used.

Usually to make a simple PWM (for practice or introduction PWM) of the hobbyist to use some of the circuit made of Op-Amp, which consists of Schmitt Trigger circuit, integrator and comparator.

Diagram of PWM Controller

Schmitt Trigger function that produces a square wave will be converted by the integrator sawtooth wave or commonly also called Ramp, and Ramp compared with a reference voltage that can be changed much voltage. So the result is a PWM output.

Skema Rangkaian Low Side PWM Motor/Light Controller

Skema Rangkaian High Side PWM Motor/Light Controller

These two schematics are variations on another PWM circuit. The diagrams are for 12V operation only and there are high side (common ground) and low side (common +12V) versions. The low side version of the circuit uses an N Channel FET, the high side version of the circuit uses a P Channel FET. N Channel devices tend to handle more current than P Channel devices, they are also less expensive. The high side version of the circuit is useful when one side of the load has to be grounded.

This circuit can switch a fairly high amount of current, an IRFZ34N MOSFET can handle over 35 Amps if connected to a proper heat sink. Higher power FETs, such as the IRFZ48N or IRF1010Z can be substituted if even larger currents are required. It is also possible to connect multiple FETs in parallel for even more current capacity. Always use thermally conductive grease between the FET and the heat sink, and remember that the heat sink is electrically live.

Inductive loads (motors) may require special care since they can generate large voltage spikes that can damage the MOSFET. Replacing the 1N4002 with a fast recovery diode may help absorb the reverse voltage kick when driving an inductive load such as a motor. If you use these circuits for experiments with electric vehicles, be sure to install a circuit breaker in series with the battery, the circuit breaker should be easy to reach by the driver. This is especially important due to the fact that when MOSFETs fail, they often short out, leaving the motor on at full speed.

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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.

Skema rangkaian multivibrator astable used IC 555

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 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.

Skema rangkaian multivibrator monostable IC 555

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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