POWER ADJUSTMENT
Most often, device power regulators are made using thyristors, using it as a powerful output switch. But a thyristor in an alternating current circuit is inconvenient because it requires power through a rectifier bridge, which, with a high load power, must be installed on a radiator. In this regard, a triac is more convenient for a key element. The main difference is the ability to switch not only direct, but also alternating current, which can flow in any direction - both from the anode to the cathode, and in the opposite direction.
For reference: triacs with a positive voltage at the anode can be turned on by pulses of any polarity supplied to the control electrode relative to the cathode, and with a negative voltage at the anode - by pulses of only negative polarity. Controlling a triac with direct current requires a lot of power, and with pulse control, a driver is needed that provides short pulses when the mains voltage passes through zero, which reduces the level of interference compared to regulators that use the phase-pulse control method.
The power control device contains a triac, a time (phase) delay unit, a compensating circuit and a power source. The compensating circuit R8 C2 adds a voltage proportional to the supply voltage to the voltage of the zener diode VD3. This sum is the base-to-base voltage of the KT117 unijunction transistor. Reducing the supply voltage reduces the supply voltage of the transistor and causes a decrease in the time delay. This differs from the well-known triac power regulator circuit on the BT136-600 and the DB-3 dinistor in the stabilization of control pulses and, accordingly, greater accuracy and consistency of the output voltage.
When setting up a power control device, you need to connect it to the network with a load across, and install a voltmeter parallel to the load. By changing the voltage with variable resistor R8 at the regulator input, we achieve the minimum voltage at the load. The transformer is made on a Sh5x6 core, the primary winding is 40 turns, the secondary winding is 50 turns PEL-0.2 - 0.3. In my version of the power control device, I installed a transformer on a K20x10x6 ferrite ring with two identical windings of 40 turns each - everything worked perfectly. To visually monitor the voltage (power) on the load, I installed a small AC voltmeter assembled from a recording level indicator of a reel-to-reel Soviet tape recorder. We connect it naturally parallel to the load. The red light indicates that the power control device is connected to the network and illuminates the scale.
This regulator can be used to connect an active load with a power of up to two kilowatts - electric stoves, electric kettles, electric fireplaces, irons, etc., and when replacing the triac with a more powerful one, for example TC132-50, up to 10 kW. A real example of use: a neighbor’s 16 A automatic machines constantly knock out the plugs when using an electric kettle Tefal 2 kW. Replacing them is impossible, since he does not live in his own apartment. The problem was solved by this adjustment device, set to 80% power.
Useful modifications: when working with an inductive load, in parallel with the power regulator triac it is necessary to turn on an RC circuit to limit the rate of rise of the anode voltage. Any triac regulator is a source of radio interference, so it is advisable to equip the power regulator with a radio interference filter. The LC radio noise filter is a conventional G-filter with a coil and a capacitor. A coil of 100 turns of wire wound on a ferrite rod with a diameter of 8 mm and a length of 50 mm is used as a choke L. A wire diameter of 1 mm corresponds to a maximum load power of approximately 700 W. A fuse for the rated load current protects the triac from a short circuit in the load. When setting up, observe safety measures, since all elements of the device for power regulation are galvanically connected to a 220 V network.
Questions and comments regarding the diagram - on
Triac power regulators operate using phase control. They can be used to change the power of various electrical devices operating using alternating voltage.
The devices may include electric incandescent lamps, heating devices, alternating current electric motors, transformer welding machines, and many others. They have a wide range of adjustment, which gives them a wide range of applications, including in everyday life.
Description and principle of operation
The operation of the device is based on regulating the turn-on delay of the triac when the mains voltage crosses zero. The triac is in the closed position at the beginning of the half-cycle. After the voltage of the positive half-wave increases, the capacitor is charged with a phase shift from the mains voltage.
This shift is determined by the resistance values of resistors P1, R1, R2, and the capacitance of capacitor C1. When the threshold value is reached on the capacitor, the triac is turned on. It becomes conductive, allowing voltage to pass through, thereby bridging the circuit with resistors and capacitors. When the half-cycle passes through 0, the triac is turned off.
Then, when the capacitor is charged, it opens again with a negative voltage wave. Such operation of a triac is possible due to its structure. It has five layers of semiconductors with a control electrode. Which gives him the opportunity to swap the anode and cathode. To put it simply, it can be represented as two thyristors with a back-to-back connection.
Application area
Triac power regulators have found their application not only in everyday life, but also in many industries. In particular, they successfully replace cumbersome relay contact control circuits. They help set optimal currents in automatic welding lines, and in many other industries.
As for the use of these devices in everyday life, its use is very diverse. From regulating the voltage of incandescent lamps to regulating the fan speed. In a nutshell, the range is so diverse that it is not easy to describe.
Types of triac power regulators
Speaking about these devices, it should be noted that they all work on the same principle. Their main difference is the power for which they are designed. The second difference will be the control scheme. Some types of triac may require finer tuning of control signals. Control can be very diverse, from a capacitor and a pair of resistors to a modern microcontroller.
Scheme
Power regulators can use many different designs. The simplest circuit is considered to be the use of a variable resistor, and the most complex is a modern microcontroller. If you use it at home, then you can stick to the simplest one.
It will be enough for most needs. In addition to adjusting the light, the regulator is often used for. Those who like to do electrical engineering at home need to regulate the temperature of the soldering iron.
It is inconvenient to do this using variable resistors, plus there are large losses of electricity. The best solution would be to use a triac regulator.
How to assemble the regulator
For assembly, let's take the simplest circuit diagram. This circuit uses triac VD2 - VTV 12-600V (600 - 800 V, 12 A), resistors: R1 -680 kOhm, R2 - 47 kOhm, R3 - 1.5 kOhm, R4 - 47 kOhm. Capacitors: C1 – 0.01 mF, C2 – 0.039 mF.
To assemble such a circuit with your own hands, you will need to do certain actions in the correct order:
- It is necessary to purchase all the parts from the list presented above.
- The second stage will be the development of a printed circuit board. When developing, it should be taken into account that some of the parts will be mounted mounted. And some of the parts will be installed directly into the board.
- Creating a board begins with drawing a picture with the location of parts and contact tracks between parts. Then the drawing is transferred to the board blank. When the drawing is transferred to the board, then everything proceeds according to a well-known method. Etching the board, drilling holes for parts, tinning the tracks on the board. Many people use modern computer programs such as Sprint Layout to obtain a board drawing, but if you don’t have them, it’s okay. In this case we have a small diagram. It can be done manually.
- When the board is ready, insert the necessary radio components into the prepared holes, shorten the length of the contacts with wire cutters to the required length and begin soldering. To do this, use a soldering iron to warm up the contact point on the board, apply solder to it, when the solder spreads over the surface at the contact point, remove the soldering iron and let the solder cool. In this case, all parts must remain in place and not move. When soldering, safety precautions should be observed. First of all, you need to protect yourself from burns; they can be caused by contact with a soldering iron, or splashes of hot solder or flux. You should have clothing that provides maximum protection to all areas of the body. And to protect your eyes, you need to wear safety glasses. The soldering area should be in a ventilated area, since corrosive gases may appear during operation.
- The final stage of assembly will be placing the resulting board into the box. Which box to choose will directly depend on the type of regulator you have. In the case of our scheme, a box the size of a plastic socket will be sufficient. A small number of parts, the largest of which is a variable resistor, take up little space and fit into a small space.
- The last step will be to check and configure the device. To do this, you will need a measuring device to monitor the voltage, and a device for the load, in our case a soldering iron. By rotating the regulator knob, you need to examine how smoothly the output voltage changes. If necessary, you can apply marks near the adjustment resistor.
Price
The market is replete with a large number of offers, with different price levels. The price of triac power regulators is primarily influenced by several parameters:
- Product power, the more powerful the power, the more expensive your device will be.
- The complexity of the control circuit, in the simplest circuits, the main cost is borne by triacs. In complex control circuits where microcontrollers are used, the price may increase due to them. They provide additional features, respectively, at a higher price. So the regulator is on a resistor with a voltage of 220 V, a power of 2500 W. costs 1200 rubles, and on a microcontroller with the same parameters 2450 rubles.
- Manufacturer's brand. Sometimes you can pay 50% more for a well-promoted brand.
Now you can find power regulators assembled according to various schemes. Each of them will have its own advantages and disadvantages. Modern regulators are divided into two types, microprocessor and analog. Analog regulators can be classified as economical class systems. They have been known since the times of the USSR, are easy to implement and cheap. Their most important disadvantage is the constant control of the owner or operator.
Let's give a simple example: you need to have a voltage of 170 V at the output. When you set this voltage, the supply voltage was 225 V, and now imagine that the input voltage has changed by 10 V, and the output voltage will change accordingly.
If the output voltage affects the process, problems may arise. In addition to the supply voltage drop, the output voltage can be affected by the parameters of the regulator itself. Since the capacitance of the capacitor changes over time, the variable resistor can be affected by environmental humidity, and it is impossible to achieve stable operation.
Microprocessor-based regulators do not have this problem. They implement feedback that allows you to quickly adjust the control signal.
One of the important aspects of long-term operation will be repair and service. Microprocessor regulators are complex products and require specialized service centers to repair them. Analog regulators are easier to repair. Any radio amateur can do it at home.
You can make the final choice on a triac power regulator after studying the conditions for its operation. When you do not need greater output accuracy, it is reasonable to give preference to an analog device, while saving money. When accuracy is required at the output, do not skimp, buy a microprocessor device.
To control some types of household appliances (for example, a power tool or a vacuum cleaner), a power regulator based on a triac is used. You can learn more about the operating principle of this semiconductor element from the materials posted on our website. In this publication we will consider a number of issues related to triac circuits for controlling load power. As always, let's start with theory.
The principle of operation of the regulator on a triac
Let us recall that a triac is usually called a modification of a thyristor that plays the role of a semiconductor switch with a nonlinear characteristic. Its main difference from the basic device is two-way conductivity when switching to the “open” operating mode, when current is supplied to the control electrode. Thanks to this property, triacs do not depend on voltage polarity, which allows them to be used effectively in circuits with alternating voltage.
In addition to the acquired feature, these devices have an important property of the base element - the ability to maintain conductivity when the control electrode is disconnected. In this case, the “closing” of the semiconductor switch occurs when there is no potential difference between the main terminals of the device. That is, when the alternating voltage crosses the zero point.
An additional bonus from this transition to the “closed” state is the reduction in the amount of interference during this phase of operation. Please note that a regulator that does not create interference can be created under the control of transistors.
Thanks to the properties listed above, it is possible to control the load power through phase control. That is, the triac opens every half-cycle and closes when crossing zero. The delay time for turning on the “open” mode, as it were, cuts off part of the half-cycle, as a result, the shape of the output signal will be sawtooth.
In this case, the signal amplitude will remain the same, which is why it is incorrect to call such devices voltage regulators.
Regulator circuit options
Let's give a few examples of circuits that allow you to control load power using a triac, starting with the simplest.
Figure 2. Circuit diagram of a simple triac power regulator powered by 220 V Designations:
- Resistors: R1- 470 kOhm, R2 – 10 kOhm,
- Capacitor C1 – 0.1 µF x 400 V.
- Diodes: D1 – 1N4007, D2 – any indicator LED 2.10-2.40 V 20 mA.
- Dinistor DN1 – DB3.
- Triac DN2 - KU208G, you can install a more powerful analog BTA16 600.
With the help of dinistor DN1, the circuit D1-C1-DN1 is closed, which moves DN2 to the “open” position, in which it remains until the zero point (completion of the half-cycle). The opening moment is determined by the accumulation time on the capacitor of the threshold charge required to switch DN1 and DN2. The rate of charge C1 is controlled by the chain R1-R2, the total resistance of which determines the moment of “opening” of the triac. Accordingly, the load power is controlled through a variable resistor R1.
Despite the simplicity of the circuit, it is quite effective and can be used as a dimmer for filament lighting or a soldering iron power regulator.
Unfortunately, the above circuit does not have feedback, therefore, it is not suitable as a stabilized speed controller of a commutator electric motor.
Feedback regulator circuit
Feedback is necessary to stabilize the speed of the electric motor, which can change under the influence of load. You can do this in two ways:
- Install a tachometer that measures the speed. This option allows for precise adjustment, but this increases the cost of implementing the solution.
- Monitor voltage changes on the electric motor and, depending on this, increase or decrease the “open” mode of the semiconductor switch.
The latter option is much easier to implement, but requires slight adjustment to the power of the electric machine used. Below is a diagram of such a device.
Designations:
- Resistors: R1 – 18 kOhm (2 W); R2 – 330 kOhm; R3 – 180 Ohm; R4 and R5 – 3.3 kOhm; R6 – must be selected as described below; R7 – 7.5 kOhm; R8 – 220 kOhm; R9 – 47 kOhm; R10 – 100 kOhm; R11 – 180 kOhm; R12 – 100 kOhm; R13 – 22 kOhm.
- Capacitors: C1 – 22 µF x 50 V; C2 – 15 nF; C3 – 4.7 µF x 50 V; C4 – 150 nF; C5 – 100 nF; C6 – 1 µF x 50 V..
- Diodes D1 – 1N4007; D2 – any 20 mA indicator LED.
- Triac T1 – BTA24-800.
- Microcircuit – U2010B.
This circuit ensures a smooth start of the electrical installation and protects it from overload. Three operating modes are allowed (set by switch S1):
- A – When overload occurs, LED D2 turns on, indicating overload, after which the engine reduces speed to minimum. To exit the mode, you must turn off and turn on the device.
- B – If there is an overload, LED D2 turns on, the motor is switched to work at minimum speed. To exit the mode, it is necessary to remove the load from the electric motor.
- C – Overload indication mode.
Setting up the circuit comes down to selecting resistance R6; it is calculated depending on the power of the electric motor using the following formula: . For example, if we need to control a 1500 W motor, then the calculation will be as follows: 0.25 / (1500 / 240) = 0.04 Ohm.
To make this resistance, it is best to use nichrome wire with a diameter of 0.80 or 1.0 mm. Below is a table that allows you to select the resistance R6 and R11, depending on the engine power.
The above device can be used as a speed controller for motors of power tools, vacuum cleaners and other household equipment.
Regulator for inductive load
Those who try to control an inductive load (for example, a welding machine transformer) using the above circuits will be disappointed. The devices will not work, and the triacs may fail. This is due to a phase shift, which is why during a short pulse the semiconductor switch does not have time to switch to the “open” mode.
There are two options to solve the problem:
- Supplying a series of similar pulses to the control electrode.
- Apply a constant signal to the control electrode until it passes through zero.
The first option is the most optimal. Here is a diagram where this solution is used.
As can be seen from the following figure, which shows oscillograms of the main signals of the power regulator, a packet of pulses is used to open the triac.
This device makes it possible to use regulators on semiconductor switches to control an induction load.
A simple power regulator on a triac with your own hands
At the end of the article, we will give an example of a simple power regulator. In principle, you can assemble any of the above circuits (the most simplified version was shown in Figure 2). For this device it is not even necessary to make a printed circuit board; the device can be assembled by surface mounting. An example of such an implementation is shown in the figure below.
This regulator can be used as a dimmer, and can also be used to control powerful electric heating devices. We recommend choosing a circuit in which a semiconductor switch with characteristics corresponding to the load current is used for control.
A semiconductor device that has 5 p-n junctions and is capable of passing current in the forward and reverse directions is called a triac. Due to the inability to operate at high frequencies of alternating current, high sensitivity to electromagnetic interference and significant heat generation when switching large loads, they are currently not widely used in high-power industrial installations.
There they are successfully replaced by circuits based on thyristors and IGBT transistors. But the compact dimensions of the device and its durability, combined with the low cost and simplicity of the control circuit, allowed them to be used in areas where the above disadvantages are not significant.
Today, triac circuits can be found in many household appliances from hair dryers to vacuum cleaners, hand-held power tools and electric heating devices - where smooth power adjustment is required.
Principle of operation
The power regulator on a triac works like an electronic key, periodically opening and closing at a frequency specified by the control circuit. When unlocked, the triac passes part of the half-wave of the mains voltage, which means the consumer receives only part of the rated power.
Do it yourself
Today, the range of triac regulators on sale is not very large. And, although the prices for such devices are low, they often do not meet consumer requirements. For this reason, we will consider several basic circuits of regulators, their purpose and the element base used.
Device diagram
The simplest version of the circuit, designed to work with any load. Traditional electronic components are used, the control principle is phase-pulse.
Main components:
- triac VD4, 10 A, 400 V;
- dinistor VD3, opening threshold 32 V;
- potentiometer R2.
The current flowing through potentiometer R2 and resistance R3 charges capacitor C1 with each half-wave. When the voltage on the capacitor plates reaches 32 V, the dinistor VD3 opens and C1 begins to discharge through R4 and VD3 to the control terminal of the triac VD4, which opens to allow current to flow to the load.
The opening duration is regulated by selecting the threshold voltage VD3 (constant value) and resistance R2. The power in the load is directly proportional to the resistance value of potentiometer R2.
An additional circuit of diodes VD1 and VD2 and resistance R1 is optional and serves to ensure smooth and accurate adjustment of the output power. The current flowing through VD3 is limited by resistor R4. This achieves the pulse duration required to open VD4. Fuse Pr.1 protects the circuit from short circuit currents.
A distinctive feature of the circuit is that the dinistor opens at the same angle in each half-wave of the mains voltage. As a result, the current does not rectify, and it becomes possible to connect an inductive load, for example a transformer.
Triacs should be selected according to the load size, based on the calculation of 1 A = 200 W.
Elements used:
- Dinistor DB3;
- Triac TS106-10-4, VT136-600 or others, the required current rating is 4-12A.
- Diodes VD1, VD2 type 1N4007;
- Resistances R1100 kOhm, R3 1 kOhm, R4 270 Ohm, R5 1.6 kOhm, potentiometer R2 100 kOhm;
- C1 0.47 µF (operating voltage from 250 V).
Note that the scheme is the most common, with minor variations. For example, a dinistor can be replaced with a diode bridge, or an interference-suppressing RC circuit can be installed in parallel with the triac.
A more modern circuit is one that controls the triac from a microcontroller - PIC, AVR or others. This circuit provides more accurate regulation of voltage and current in the load circuit, but is also more complex to implement.
Triac power regulator circuit Assembly
The power regulator must be assembled in the following sequence:
- Determine the parameters of the device on which the device being developed will work. Parameters include: number of phases (1 or 3), the need for precise adjustment of output power, input voltage in volts and rated current in amperes.
- Select the type of device (analog or digital), select elements according to load power. You can check your solution in one of the programs for modeling electrical circuits - Electronics Workbench, CircuitMaker or their online analogues EasyEDA, CircuitSims or any other of your choice.
- Calculate the heat dissipation using the following formula: voltage drop across the triac (about 2 V) multiplied by the rated current in amperes. The exact values of the voltage drop in the open state and the rated current flow are indicated in the characteristics of the triac. We get the power dissipation in watts. Select a radiator according to the calculated power.
- Purchase the necessary electronic components, radiator and printed circuit board.
- Lay out contact tracks on the board and prepare sites for installing elements. Provide mounting on the board for a triac and radiator.
- Install the elements onto the board using soldering. If it is not possible to prepare a printed circuit board, then you can use surface mounting to connect the components using short wires. When assembling, pay special attention to the polarity of connecting the diodes and triac. If there are no pin markings on them, then there are “arcs”.
- Check the assembled circuit with a multimeter in resistance mode. The resulting product must correspond to the original design.
- Securely attach the triac to the radiator. Don’t forget to lay an insulating heat transfer gasket between the triac and the radiator. The fastening screw is securely insulated.
- Place the assembled circuit in a plastic case.
- Remember that at the terminals of the elements Dangerous voltage is present.
- Turn the potentiometer to minimum and perform a test run. Measure the voltage at the regulator output with a multimeter. Smoothly turn the potentiometer knob to monitor the change in output voltage.
- If the result is satisfactory, then you can connect the load to the output of the regulator. Otherwise, it is necessary to make power adjustments.
Triac power radiator Power adjustment
The power control is controlled by a potentiometer, through which the capacitor and the capacitor discharge circuit are charged. If the output power parameters are unsatisfactory, you should select the resistance value in the discharge circuit and, if the power adjustment range is small, the potentiometer value.
- extend lamp life, adjust lighting or soldering iron temperature A simple and inexpensive regulator using triacs will help.
- select the circuit type and component parameters according to the planned load.
- work it out carefully circuit solutions.
- be careful when assembling the circuit, observe the polarity of semiconductor components.
- do not forget that electric current exists in all elements of the circuit and it is deadly to humans.
A selection of circuits and a description of the operation of a power regulator using triacs and more. Triac power regulator circuits are well suited for extending the life of incandescent lamps and for adjusting their brightness. Or for powering non-standard equipment, for example, 110 volts.
The figure shows a circuit of a triac power regulator, which can be changed by changing the total number of network half-cycles passed by the triac over a certain time interval. The elements of the DD1.1.DD1.3 microcircuit are made with an oscillation period of about 15-25 network half-cycles.
The duty cycle of the pulses is regulated by resistor R3. Transistor VT1 together with diodes VD5-VD8 is designed to bind the moment the triac is turned on during the transition of the mains voltage through zero. Basically, this transistor is open, respectively, a “1” is sent to the input DD1.4 and transistor VT2 with triac VS1 are closed. At the moment of crossing zero, transistor VT1 closes and opens almost immediately. In this case, if the output DD1.3 was 1, then the state of the elements DD1.1.DD1.6 will not change, and if the output DD1.3 was “zero”, then the elements DD1.4.DD1.6 will generate a short pulse, which will be amplified by transistor VT2 and open the triac.
As long as there is a logical zero at the output of the generator, the process will proceed cyclically after each transition of the mains voltage through the zero point.
The basis of the circuit is a foreign triac mac97a8, which allows you to switch high-power connected loads, and to regulate it I used an old Soviet variable resistor, and used a regular LED as an indication.
The triac power regulator uses the principle of phase control. The operation of the power regulator circuit is based on changing the moment the triac is turned on relative to the transition of the mains voltage through zero. At the initial moment of the positive half-cycle, the triac is in the closed state. As the mains voltage increases, capacitor C1 is charged through a divider.
The increasing voltage on the capacitor is shifted in phase from the mains voltage by an amount depending on the total resistance of both resistors and the capacitance of the capacitor. The capacitor is charged until the voltage across it reaches the “breakdown” level of the dinistor, approximately 32 V.
At the moment the dinistor opens, the triac will also open, and a current will flow through the load connected to the output, depending on the total resistance of the open triac and the load. The triac will be open until the end of the half-cycle. With resistor VR1 we set the opening voltage of the dinistor and triac, thereby regulating the power. At the time of the negative half-cycle, the circuit operation algorithm is similar.
Option of the circuit with minor modifications for 3.5 kW
The controller circuit is simple, the load power at the output of the device is 3.5 kW. With this homemade amateur radio you can adjust lighting, heating elements and much more. The only significant drawback of this circuit is that you cannot connect an inductive load to it under any circumstances, because the triac will burn out!
Radio components used in the design: Triac T1 - BTB16-600BW or similar (KU 208 or VTA, VT). Dinistor T - type DB3 or DB4. Capacitor 0.1 µF ceramic.
Resistance R2 510 Ohm limits the maximum volts on the capacitor to 0.1 μF; if you put the regulator slider in the 0 Ohm position, the circuit resistance will be about 510 Ohms. The capacitance is charged through resistors R2 510 Ohm and variable resistance R1 420 kOhm, after U on the capacitor reaches the opening level of dinistor DB3, the latter will generate a pulse that unlocks the triac, after which, with further passage of the sinusoid, the triac is locked. The opening and closing frequency of T1 depends on the level of U on the 0.1 μF capacitor, which depends on the resistance of the variable resistor. That is, by interrupting the current (with a high frequency) the circuit thereby regulates the output power.
With each positive half-wave of the input alternating voltage, capacitance C1 is charged through a chain of resistors R3, R4, when the voltage on capacitor C1 becomes equal to the opening voltage of dinistor VD7, its breakdown will occur and the capacitance will be discharged through the diode bridge VD1-VD4, as well as resistance R1 and control electrode VS1. To open the triac, an electrical chain of diodes VD5, VD6, capacitor C2 and resistance R5 is used.
It is necessary to select the value of resistor R2 so that at both half-waves of the mains voltage, the regulator triac operates reliably, and it is also necessary to select the values of resistances R3 and R4 so that when rotating the variable resistance knob R4, the voltage on the load smoothly changes from minimum to maximum values. Instead of the TC 2-80 triac, you can use TC2-50 or TC2-25, although there will be a slight loss in the permissible power in the load.
KU208G, TS106-10-4, TS 112-10-4 and their analogs were used as a triac. At the moment when the triac is closed, capacitor C1 is charged through the connected load and resistors R1 and R2. The charging speed is changed by resistor R2, resistor R1 is designed to limit the maximum value of the charge current
When the threshold voltage value is reached on the capacitor plates, the switch opens, capacitor C1 is quickly discharged to the control electrode and switches the triac from the closed state to the open state; in the open state, the triac bypasses the circuit R1, R2, C1. At the moment the mains voltage passes through zero, the triac closes, then capacitor C1 is charged again, but with a negative voltage.
Capacitor C1 from 0.1...1.0 µF. Resistor R2 1.0...0.1 MOhm. The triac is switched on by a positive current pulse to the control electrode with a positive voltage at the conventional anode terminal and by a negative current pulse to the control electrode with a negative voltage at the conventional cathode. Thus, the key element for the regulator must be bidirectional. You can use a bidirectional dinistor as a key.
Diodes D5-D6 are used to protect the thyristor from possible breakdown by reverse voltage. The transistor operates in avalanche breakdown mode. Its breakdown voltage is about 18-25 volts. If you don’t find P416B, then you can try to find a replacement for it.
The pulse transformer is wound on a ferrite ring with a diameter of 15 mm, grade N2000. The thyristor can be replaced with KU201
The circuit of this power regulator is similar to the circuits described above, only the interference suppression circuit C2, R3 is introduced, and the switch SW makes it possible to break the charging circuit of the control capacitor, which leads to instant locking of the triac and disconnecting the load.
C1, C2 - 0.1 MKF, R1-4k7, R2-2 mOhm, R3-220 Ohm, VR1-500 kOhm, DB3 - dinistor, BTA26-600B - triac, 1N4148/16 V - diode, any LED.
The regulator is used to regulate load power in circuits up to 2000 W, incandescent lamps, heating devices, soldering iron, asynchronous motors, car charger, and if you replace the triac with a more powerful one, it can be used in the current regulation circuit in welding transformers.
The principle of operation of this power regulator circuit is that the load receives a half-cycle of the mains voltage after a selected number of skipped half-cycles.
The diode bridge rectifies alternating voltage. Resistor R1 and zener diode VD2, together with the filter capacitor, form a 10 V power source to power the K561IE8 microcircuit and the KT315 transistor. The rectified positive half-cycles of the voltage passing through capacitor C1 are stabilized by the zener diode VD3 at a level of 10 V. Thus, pulses with a frequency of 100 Hz follow to the counting input C of the K561IE8 counter. If switch SA1 is connected to output 2, then a logical one level will be constantly present at the base of the transistor. Because the microcircuit reset pulse is very short and the counter manages to restart from the same pulse.
Pin 3 will be set to a logical one level. The thyristor will be open. All power will be released at the load. In all subsequent positions of SA1 at pin 3 of the counter, one pulse will pass through 2-9 pulses.
The K561IE8 chip is a decimal counter with a positional decoder at the output, so the logical one level will be periodic at all outputs. However, if the switch is installed on output 5 (pin 1), then counting will only occur up to 5. When the pulse passes through output 5, the microcircuit will be reset to zero. Counting will begin from zero, and a logical one level will appear at pin 3 for the duration of one half-cycle. During this time, the transistor and thyristor open, one half-cycle passes to the load. To make it clearer, I present vector diagrams of the circuit operation.
If you need to reduce the load power, you can add another counter chip by connecting pin 12 of the previous chip to pin 14 of the next one. By installing another switch, you can adjust the power up to 99 missed pulses. Those. you can get about a hundredth of the total power.
The KR1182PM1 microcircuit has two thyristors and a control unit for them. The maximum input voltage of the KR1182PM1 microcircuit is about 270 Volts, and the maximum load can reach 150 Watts without the use of an external triac and up to 2000 W with the use, and also taking into account the fact that the triac will be installed on the radiator.
To reduce the level of external noise, capacitor C1 and inductor L1 are used, and capacitance C4 is required for smooth switching on of the load. The adjustment is carried out using resistance R3.
A selection of fairly simple regulator circuits for a soldering iron will make life easier for a radio amateur.
Combination consists in combining the ease of use of a digital regulator and the flexibility of adjusting a simple one.
The considered power regulator circuit works on the principle of changing the number of periods of the input alternating voltage going to the load. This means that the device cannot be used to adjust the brightness of incandescent lamps due to visible blinking. The circuit makes it possible to regulate power within eight preset values.
There are a huge number of classic thyristor and triac regulator circuits, but this regulator is made on a modern element base and, in addition, was phase-based, i.e. does not transmit the entire half-wave of the mains voltage, but only a certain part of it, thereby limiting the power, since the triac opens only at the required phase angle.
