Parameters of Nonlinear Delayed Circuit

This is a design schematic circuit diagram for parameters of nonlinear delayed circuit. This circuit is based on LM 324 as brain of the controller. The nonlinearity is built up of the transistor T 1 , the adjustable amplifier OA 1 and the resistors R 2-R 7. Electronic components: delay line: bucket brigade line MN 3011 with 3328 stages, triggered by MN 3101 (both National Panasonic); OA 1 :LM 324N; C = 660 pF; R 1 = 470 k,R 2 = 100 k lin., R 3 = 22 k, R 4 = 4.7k,R 5 = 10 k,R 6 = 1k,R 7 = 47 k;T 1 BC 238C. This the figure of the circuit schematic.

5 A Constant Voltage Constant Current Regulator Circuit

Here’s a design circuit that doesn’t mean a system with a constant load, since there will be no regulation in such case. What we call CVCS regulator is a regulator with two modes. Here’s the figure of the circuit; 

The first mode is constant voltage, where the regulator trying to regulate the supply to a variable load at a constant voltage. In this mode off course the current will be variable depending on the load. The current will vary a range that is limited to a predetermined maximum current level. When the load draw more current than this level then the regulator will switch to constant current mode, where the regulator keep the current at a fixed maximum value. Any attempt of the load to draw more current will cause the regulator to decrease the voltage as a reaction to keep it constant, so it acts like a current limiter. Here is the schematic diagram of the CVCS regulator.

Optimizing High-Voltage Common Mode Circuit

Here’s a design circuit for to measure the Avago Technologies ACPL-M61L’s high-voltage common mode rejection (HVCMR). Three production samples were randomly selected for the measurements. VDD1 is the transmitter supply voltage used to turn on the LED. Limiting resistor R1 is connected to the LED anode and R2 is connected to the LED cathode. R1 and R2 connected in this common-mode fashion, rather than a single resistor, enhances CMR performance. Here’s the figure of the design circuit;

Common mode noise is often seen at the system application level where there is a diff erence in the ground levels of an isolating component’s input control circuitry and output control circuitry. This is especially true when a ground line is floating (device ground connected to a common line). In the ACPL-x6xL family, the common mode rejection (CMR) specification indicates the ability to reject common mode noise. This is also known as common mode transient rejection (CMTR). CMTR s). Thedescribes the maximum tolerable rising/falling rate of a common mode voltage (given in volts per microsecond, V/ CMTR specification includes the amplitude of the common mode voltage (VCM) that can be tolerated. The common mode voltage slew rate that the optocoupler can tolerate and hold the correct output state is referred to as common mode transient immunity (CMTI).

Common mode noise can be coupled to the opto coupler output by external circuitry. Common mode noise, especially in a high electromagnetic interference (EMI) environment, can adversely affect the output state of the opto coupler through a conductive medium, primarily capacitive and inductive parasitics, Metallic printed circuit board (PCB) tracks that operate at high frequency can couple charge to the LED input pin or to the opto coupler output pin through parasitic capacitors between adjacent metal tracks. It is often difficult to identify the root cause of common mode noise or interference that is introduced by the circuit/system/application or by other forms of external factors that couple noise. When the source of common mode noise is identified, corrective measures are easy to implement by adding decoupling capacitors or filters to the system, or by adding some form of shielding.

5 A Constant Voltage-Constant Current Regulator Circuit

This is a design circuit for constant voltage constant current (CVCS) regulator doesn’t mean a system with a constant load, since there will be no regulation in such case.  What we call CVCS regulator is a regulator with two modes. This is the figure of the circuit;

The first mode is constant voltage, where the regulator trying to regulate the supply to a variable load at a constant voltage. In this mode off course the current will be variable depending on the load. The current will vary a range that is limited to a predetermined maximum current level. When the load draw more current than this level then the regulator will switch to constant current mode, where the regulator keep the current at a fixed maximum value. Any attempt of the load to draw more current will cause the regulator to decrease the voltage as a reaction to keep it constant, so it acts like a current limiter. Here is the schematic diagram of the CVCS regulator.

Active Power Factor Correction Circuit

Active power factor correction stabilize the electrical demand of a device to give the best power factor characteristic of many types of loads.  To meet power factor regulation, a low cost solution should be designed. In many application, the need of high DC voltage is usually implemented by a direct rectification of the AC line followed by bulk capacitor filtering. This is the figure the circuit;

 

This capacitor filtering introduce current spike that distort the power line sine waveform, and this introduce a poor power factor, resulting in an apparent input power that is much higher than the real power. This can be solved by inserting a pre-regulation between the rectifier and the bulk capacitor. We call this pre-regulator circuit as power factor correction circuit. This power factor controller is a low–cost system solution for boost mode follower. that meets IEC1000–3–2 standard. This power factor correction circuit includes an inrush current detection, protection against over current, overvoltage and under voltage. Follower boost mode for system cost reduction – smaller inductor and MOSFET can be used. [Circuit diagram source: ON Semiconductor Application Notes]

12V Stroboscope Circuit

Usually many stoboscope circuit work directly from mains voltage, but this circuit uses 12V DC instead on mains AC. The circuit has some special functions compared to other stroboscope circuits found electronics books. First the there is a switch for selecting the flash power: with C3 you can get very fast flash rates (over 50 Hz), C2 is most suitable for normal operation and using C1 directly you get very bright single flashes. This is the figure of the circuit;

The stoboscope tube needs about 250-400V DC to operate. This high voltage is generated using simple voltage step up circuit built from transistors Q1,Q2 and transformer T1. This circuit gives out about 230V AC voltage which is then rectified with rectifying bridge U1 (must have at least 400V voltage rating) and stored to the main capacitor C1. This approach gave me nice flash tube with reflector, trigger transformer and some of the capacitors (for example C1). Other parts were the one luying around.

Using Current Source to Make Linear Scale Analog Ohm Meter

Many analog ohm meters have non linear scale, so the resolution become worse at higher resistance value. This because they use cheap current source, only a series resistance to approximate an ideal current source. An ideal current source will force a consistent current amount regardless of the tested resistor value.  Using regulated current source, the current flowing through the tested resistor will be kept constant, so the measured voltage across the tested resistor is proportional (linear) to its resistance value. This is the figure of the circuit.

The current source is provided by IC1a. The two 1N4148 diodes give a constant reference, so the voltage across selected R2..R6 is constant at about 1.4 volt. The R1..R6 is selected to measure different resistor ranges. The VR1 has to be adjusted every time you switch for different range, just like as you do in your old classic analog ohmmeter.

Under Voltage Lockout for Buck Circuit Using LM2575

This is a implementation for buck boost configuration. This circuit is control by LM2575. This is the figure of the circuit.


In some applications it is desirable to keep the regulator off until the input voltage reaches a certain threshold. These circuits keep the regulator off until the input voltage reaches a predetermined level.
VTH ≈ VZ1 + 2VBE (Q1)

Negative Booster Regulator

This is a circuit for the variation on the buck-boost topology is the negative boost configuration. This circuit is based on LM2575-12. This is the figure of the circuit.


The circuit accepts an input voltage ranging from −5V to −12V and provides a regulated −12V output. Input voltages greater than −12V will cause the output to rise above −12V, but will not damage the regulator. Because of the boosting function of this type of regulator, the switch current is relatively high, especially at low input voltages. Output load current limitations are a result of the maximum current rating of the switch. Also, boost regulators can not provide current limiting load protection in the event of a shorted load, so some other means (such as a fuse) may be necessary. [Circuit’s source: National Semiconductor Notes].

Inverting Buck Boost Circuit Using LM2575

This is a design circuit for inverter circuit. The circuit is built by LM2575. This is the figure of the circuit.


LM2575-12 in a buck-boost configuration to generate a negative 12V output from a positive input voltage. This circuit bootstraps the regulator's ground pin to the negative output voltage, then by grounding the feedback pin, the regulator senses the inverted output voltage and regulates it to −12V. For an input voltage of 12V or more, the maximum available output current in this configuration is approximately 0.35A. At lighter loads, the minimum input voltage required drops to approximately 4.7V. The switch currents in this buck-boost configuration are higher than in the standard buck-mode design, thus lowering the available output current. Also, the start-up input current of the buck-boost converter is higher than the standard buck-mode regulator, and this may overload an input power source with a current limit less than 1.5A. [Circuit’s source: National Semiconductor Notes].