Variable Adaptor ( 3 , 4 , 5, 9, 12 sampai 37 volt)

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Variable Adapter (3 , 4 ,5 ,9 ,12 ,16 ,20 to max 37 volt)

The LM117 series of adjustable 3-terminal positive voltage regulators is capable of supplying in excess of 1.5A over a 1.2V to 37V output range. They are exceptionally easy to use and require only two external resistors to set the output voltage. Further, both line and load regulation are better than standard fixed regulators. Also, the LM117 is packaged in standard transistor packages which are easily mounted and handled.

In addition to higher performance than fixed regulators, the LM117 series offers full overload protection available only in IC's. Included on the chip are current limit, thermal overload protection and safe area protection. All overload protection circuitry remains fully functional even if the adjustment terminal is disconnected.

Normally, no capacitors are needed unless the device is situated more than 6 inches from the input filter capacitors in which case an input bypass is needed. An optional output capacitor can be added to improve transient response. The adjustment terminal can be bypassed to achieve very high ripple rejection ratios which are difficult to achieve with standard 3-terminal regulators.

Besides replacing fixed regulators, the LM117 is useful in a wide variety of other applications. Since the regulator is “floating” and sees only the input-to-output differential voltage, supplies of several hundred volts can be regulated as long as the maximum input to output differential is not exceeded, i.e., avoid short-circuiting the output.

Also, it makes an especially simple adjustable switching regulator, a programmable output regulator, or by connecting a fixed resistor between the adjustment pin and output, the LM117 can be used as a precision current regulator. Supplies with electronic shutdown can be achieved by clamping the adjustment terminal to ground which programs the output to 1.2V where most loads draw little current.

For applications requiring greater output current, see LM150 series (3A) and LM138 series (5A) data sheets. For the negative complement, see LM137 series data sheet.

Gamabr skema Rangkaian Adaptor Variable 1.2 - 37 Volt

to set the output you can use the formula below. or with a set 5k VR, the output 1.2 volt anad smallest maximal 25 volt

Features Adjustable Regulator LM117/LM317A/LM317

• Guaranteed 1% output voltage tolerance (LM317A)
• Guaranteed max. 0.01%/V line regulation (LM317A)
• Guaranteed max. 0.3% load regulation (LM117)
• Guaranteed 1.5A output current
• Adjustable output down to 1.2V
• Current limit constant with temperature
• Pa Product Enhancement tested
• 80 dB ripple rejection
• Output is short-circuit protected

Table LM117/LM317A/LM317

Rangkaian Variable frequency oscillator

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555 timer IC provides practical solutions and relatively inexpensive for a variety of electronic applications related to the timing (timing). Especially two of the most popular application is a series of monostable and astable timing. The main components of this IC consists of comparators and flip-flop is realized with a lot of transistors.

The principle component of this type of work does not change but each manufacturer makes the IC design and technology different. Almost all manufacturers make this type of component, although with a different. For example National Semiconductor LM555 call it, Philips and Texas Instruments SE/NE555 call. Motorola / ON-Semi designed with CMOS transistors that power consumption was small enough and called it MC1455. Philips and Maxim make his version of the CMOS ICM7555 name. Although different names, but the function of each diagram and pin compatible with each other. It's just that there are several different specific characteristics such as power consumption, maximum frequency and so on.

Variable frequency oscillator

Skema Rangkaian Variable frequency oscillator

HereNE55 is wired as an astable multivibrator ,whose out put frequency can be varied by varying a potentiometer.This circuit is a must in the work bench of a electronic hobbyist.Frequencies ranging from several Hz to several KHz can be obtained using this circuit.For very low frequencies (few Hz) replace C with a higher value electrolytic capacitor.

The values of R and C can be obtained using the following equations.

1/f = 0.69 * C * ( R1 + 2*R2).

% duty cycle = 100*(R1+R2)/(R1+ 2*R2) .

The good option is to select R1 in K Ohms and R2 in M Ohms.

Rangkaian Regulator Variable Sederhana

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Regulator Variable Sederhana

A simple but less efficient method of controlling a DC voltage is to use a voltage divider and transistor emitter follower configuration. The figure below illustrates using a 1K pot to set the base voltage of a medium power NPN transistor.

Skema Rangkaian Regulator Variable Sederhana

The collector of the NPN feeds the base of a larger PNP power transistor which supplies most of the current to the load. The output voltage will be about 0.7 volts below the voltage of the wiper of the 1K pot so the output can be adjusted from 0 to the full supply voltage minus 0.7 volts. Using two transistors provides a current gain of around 1000 or more so that only a couple milliamps of current is drawn from the voltage divider to supply a couple amps of current at the output.

Note that this circuit is much less efficient than the 555 timer dimmer circuit using a variabe duty cycle switching approach. A fairly large heat sink is required to prevent the PNP power transistor from overheating. The advantage of the circuit is simplicity, and also that it doesn't generate any RF interference as a switching regulator does. The circuit can be used as a voltage regulator if the input voltage remains constant.