Adjustable Regulator Circuit Using TL431

Here’s a circuit for simple Adjustable voltage regulator power supply circuit, at use integrated number circuit TL431. By from the circuit can fine volt 3V – 30V, depend on feed volt supply input and change the value R2, R1. This is the figure of the circuit;

It follow a formula calculates Vout = (1+R1/R2), Vref = 3V-30V, but this circuit gives current get not tall 100mA only. It just if want to enhance current, must use the transistor helps to enlarge current, such as 2N3055, TIP41 numbers or the other.

Simple TRIAC Crowbar For AC Or DC Lines

A TRIAC Crowbar circuit which works for both AC and DC voltage is shown in the schematic diagram below. This circuit is provide overvoltage protection for electronic or electrical equipment against excessive supply voltage.  Crowbar circuit provides two level of protection. 

First, this protection circuit will drop the voltage across the protected equipment to near zero by shorting the voltage, and second, the circuit will blow the fuse since it short the current. This is the figure of the circuit;

Using the values for R2, R3 and R1 as shown in the schematic diagram, this circuit can operate within range of 42 to 84 VAC or 60 to 120VDC. R2 set operating point where the crowbar will be triggered. To be safe, the TRIAC voltage rating should be greater than that triggering point, actually it should handle the highest possible voltage exposure. To accommodate testing, when we need to check if the crowbar action is triggered without blowing the fuse, a testing switch is provided (normally closed push button). An alarm unit can be added in parallel with the lamp for audible indication in testing crowbar action. [Circuit diagram source: seekic.com]

Simple LM2576 Switching Regulator

This is a circuit that can be used to produce any output voltage, an external feedback resistors can be added. The sLM2576 is a Switching Regulator that can produce 15, 12, 5, 0r 3.3V output voltage from maximum supply voltage of 60V or 40V. This LM2476 featured with voltage reference, switch and feedback path for use in either the negative boost or the buck saturation voltage of The LM2576 switch is typically 1.4V. A heat sink may be needed to solve the power dissipation, however the thermal dissipation is internally limited. The LM2576 has quiescent current of 50 µA in standby (on/off high). This circuit is a testing circuit for LM276. This is the figure of the circuit;

The electrolytic capacitors at output and input should be connected with leads as close as possible. The power dissipation must be small because the load is 100R, so the heat sink is not needed. The capacitor’s voltage must higher than the voltages used in the experiment. This circuit uses 40V, 1A Schottky diode or the 40V, 3A 1N5822 for heavier currents.

Simple Programmable Voltage Regulator Using L200 IC

This is a simple programmable voltage regulator circuit. With this circuit we can generate a voltage according to our wishes. This circuit is based on L200 IC. This is the figure of the circuit;

Potentiometer R2 is used to fix the output voltage Vo. Following equation show value of the output voltage:

Vo=Vref (1+(R2/R1))

We can obtain a wide range of fixed output voltage by substituting the potentiometer with a fixed resistor and choosing suitable values for R2 and R1.

[Circuit source: SGS-Thomson Application Note]

Simple Isolating A Capacitive Load Circuit

This is a simple design circuit for capacitive load. This circuit is based on LF411 or LF441 op amps IC. This is the figure of the circuit;


Both the LF411 and LF441 families have a lot of trouble driving more than about 200 pF without oscillating. Standard techniques to get around this problem are to add a small resistor (about 50X) in series with the output or to use one of the LF356 family (the 356 itself being the most popular for this purpose). An explanation of why the 356 output stage is so unusually strong is provided in the second reference listed. When extra output filtering is desired, a series RC damper will often be more effective than just a large filter capacitor.

[Circuit source: National Semiconductor Notes].

Simple Programmable Voltage Regulator Circuit Using L200 IC

This is a circuit a programmable voltage regulator circuit. With this circuit we can generate a voltage according to our wishes. This circuit uses L200 IC. This is the figure of the circuit.


Potentiometer R2 is used to fix the output voltage Vo. Following equation show value of the output voltage:

Vo=Vref (1+(R2/R1))

We can obtain a wide range of fixed output voltage by substituting the potentiometer with a fixed resistor and choosing suitable values for R2 and R1. [Source: SGS-Thomson Application Note].

Simple Voltage Comparator Circuit

This circuit is design for indicates when the input voltage differs from two defined limits, V1 and V2. This is a simple design circuit. This circuit is work with based on op amp using the CA3140 MOSFET. Here’s the schematic circuit diagram.


The supply voltage, Vcc must be higher than the highest input voltage by at least 2 volts. One application here is to monitor a 12V car battery. V1 can be set to 14V and V2 to 11V thus giving an indication of more than the cost or weak batteries. They are used to advantage because they have less output offset voltage and can switch to 0volts close. If any other use op-amps like the LF351 or CA741, it will need to have an offset null control. This is just a 10k preset reached between pins 1 and 5, the wiper connected to the negative supply op-amps or 4 pins. With this circuit the op-amp will turn on the LED if the input voltage out of limits, the two 1N4148 diodes to form an “AND”-gate at the output. Input voltage to be monitored are fed through a series of 10k resistors on the input of both op-amps. If the input voltage is greater than the limit set by V1 it will CA3140 output swing to almost full supply voltage and LED lights. Similarly, if the input voltage is less than the limit set by V2 the op-amp will swing to the Vcc and the LED light.

Simple Voltage Regulator using LM338

This circuit is a circuit diagram power supply. Circuit diagram works on voltage +13.8 V 5A with electric currents. This circuit controlled by the LM338 IC. This is the figure of the circuit.


Many times we need a supply of relatively strong in the framework we provide a variety of equipment with + 13.8V, as transceivers CB, cargo lead-acid batteries, and others known to use the circuit capable of providing complete in his exit, when This continuously operating 5A and 12A peak current. Not only need a few external components. Setting the voltage at + 13.8V to the trimmer TR1, (multiturn). The IC1 LM338 must in each case is placed on one suitable heat sink, which both supported by one fan. All the connections by the circuit become with big cross-section cable, because the current through from within their already high enough.

Part:
R1=270R 1/4W 2%
TR1=4k7 (Multiturn)
C1=10000uF 40V
C2-3=100 nF 100V Polyester
C4-5=10uF 25V
D1-2=1N4002 (1A/100V)
B1=25A Bridge Rectifier
IC1=LM338
T1=220Vac/15VAC – 8A Mains Transformer
S1=2 Pole Single Throw Mains Switch
F1=250mA Fuse