Very often there is a need to regulate the brightness of the lamp within a certain value, usually from 20 to 100% brightness. It makes no sense to do less than 20%, since the lamp will not give a luminous flux, but only a weak glow will occur, which can be useful only for decorative purposes. You can go to the store and buy a finished product, but now these devices are inadequate, to put it mildly. Since you and I are jack of all trades, we will make these devices with our own hands. Today we will consider several schemes, thanks to which it will become clear to you how to make a 12 and 220 V dimmer with your own hands.
Content:
- On a triac
- On thyristors
- Condenser dimmer
- On a microcircuit
On a triac
To begin with, consider the circuit of a dimmer operating from a 220 Volt network. This type of device works on the principle of phase displacement of the opening of the power switch. The heart of the dimmer is an RC circuit of a certain value. Control pulse shaping unit, symmetrical dynistor. And actually the power switch itself, the triac.
Let's consider how the circuit works. Resistors R1 and R2 form a voltage divider. Since R1 is variable, it changes the voltage in the R2C1 chain. The dynistor DB3 is connected to the point between them and when the voltage of the opening threshold on the capacitor C1 is reached, it is triggered and gives a pulse to the power switch of the triac VS1. It opens and passes current through itself, thereby turning on the network. The position of the regulator determines at what moment of the phase wave the power switch will open. It can be 30 Volts at the end of the wave, and 230 Volts at the peak. Thus, supplying part of the voltage to the load. The diagram below shows the process of adjusting the lighting with a dimmer on a triac.
In these graphs, the value (t *) is the time during which the capacitor is charged to the opening threshold, and the faster it picks up voltage, the earlier the key turns on, and the more voltage is applied to load. This dimmer circuit is simple and easy to repeat in practice. We recommend watching the video below, which clearly shows how to make a dimmer on a triac:
Triac power regulator 1000 W
On thyristors
If you have a bunch of old TVs and other things gathering dust in the bins of the crazy people, you can not buy a triac, but make a simple dimmer on thyristors. The circuit is slightly different from the previous one, in that each half-wave has its own thyristor, and thus its own dinistor for each key.
Let's briefly describe the regulation process. During the positive half-wave, the capacitance C1 is charged through the chain R5, R4, R3. When the opening threshold of the V3 dinistor is reached, the current through it enters the control electrode V1. The key opens by passing a positive half-wave through itself. With a negative phase, the thyristor is locked, and the process is repeated for another key V2, charging through the chain R1, R2, R5.
Phase regulators - dimers can be used not only to adjust the brightness of incandescent lamps, but also to adjusting the rotation speed of the hood fan, make an attachment for a soldering iron and adjust in this way the temperature of his sting. Also, using a homemade dimmer, you can adjust the speed of a drill or vacuum cleaner and many other applications.
Video assembly instruction:
Assembling a thyristor dimmer
Important! This control method is not suitable for work with fluorescent, economical compact and LED lamps.
Condenser dimmer
Along with smooth regulators, capacitor devices have become widespread in everyday life. The operation of this device is based on the dependence of the transmission of alternating current on the value of the capacity. The larger the capacitance of a capacitor, the more current it passes through its poles. This type of homemade dimmer can be quite compact, and depends on the required parameters, the capacitance of the capacitors.
As you can see from the diagram, there are three positions of 100% power, through the quenching capacitor and off. The device uses non-polar paper capacitors that can be obtained from old technology. About, how to properly solder radio components from boards we told in the corresponding article!
Below is a table with the parameters of the capacitance-voltage on the lamp.
Based on this scheme, you can assemble a simple night light yourself, using a toggle switch or switch to control the brightness of the lamp.
On a microcircuit
To regulate the power to the load in 12 Volt DC circuits, integral stabilizers - KRENKs are often used. The use of the microcircuit simplifies the design and installation of devices. This homemade dimmer is easy to set up and has protection features.
With the help of a variable resistor R2, a reference voltage is created at the control electrode of the microcircuit. Depending on the set parameter, the output value is adjusted from a maximum of 12V to a minimum of tenths of a Volt. The lack of these regulators is the need to install an additional radiator for good cooling KREN, since part of the energy is released on it in the form of heat.
This dimmer was repeated by me and did an excellent job with a 12 Volt LED strip, three meters long and the ability to dim the LEDs from zero to maximum. For not very lazy craftsmen, you can offer to make a dimmer at home on an integral 555 timer, which controls the KT819G power switch, with short PWM pulses.
In this mode, the transistor is in two states: fully open or fully closed. The voltage drop across it is minimal and allows you to use a circuit with a small radiator, which, compared to the previous circuit with the KREN regulator, compares favorably in size and efficiency.
Finally, we recommend watching another master class, which shows how you can make a dimmer for LEDs:
Making a dimmer for 12 volts
That's actually all the ideas for assembling a simple dimmer at home. Now you know how to make a dimmer with your own hands for 220 and 12V.
It will be interesting to read:
- DIY LED floodlight
- Dimmer repair at home
- How to pay less for light