Triac Circuit

Thyristor / TRIAC Tester

This is a simple but effective and thyristor TRIAC Tester. Operation at a good thyristor / triac: LED lights when SW3 is pressed. LED turns off when SW2 is pressed. If this occurs, the thyristor / triac OK. Tip: Hirschmann clips for the tested thyristor / triac connecting, including this quotation terminals. The supply voltage is 9V, with a minimum current of 400mA. ..

Triac mains light dimmer

This is the schematic of the conventional light dimmer. L1 and C2, C3 form the lichtnetontstoring. In this circuit meets almost every TRIAC as a TIC226D. For C1, C2 and C3 good capacitors (MKT example) with a minimum operating voltage of 400V. ..

4 channels Lamp organ

This light organ is on the speaker output of the amplifier. The lamps lit on the rhythm of the music. The input signal is amplified by a transformer. Then it goes through a monolingual filters comprising resistors and capacitors to the pots and then to the triacs. By the filters respond to each triac a separate frequency, T1 is the bass and T4 for the high. P2 to P5, the sensitivity for each set triac. P1 controls the sensitivity of the whole circuit. ..

Electronic Thermostat

Here is a circuit that implements phase-control of heaters, adjusting their power smoothly from zero to around 95% of the rated power, keeping the room temperature to within 1 or 2 degrees, while using few components. Notice that this is entirely an AC design. The TRIAC, DIAC, capacitor, resistor, potentiometer and thermistor are all AC devices. I did not have a suitable MOV at hand, so I used two Zener diodes in back-to-back fashion. The poorest aspect is that I don't know of the existence of any AC transistors, so I had to pair two complementary ones, joining the collectors through diodes, thus creating my AC transistor from 4 parts!..

Semiconductor relay circuit

This document tries to collect information about semiconductor relays and semiconductor relay circuit to one document which would be useful to electronics professionals and hobbyist. This document is a collection of information from various sources and I have not been able to verify all information. Be aware that there might be errors in the schematics...

I did not bother to draw out the receiver section because it is quite ordinary. The TRIAC switch section shown below can be controlled by ordinary 4000 series CMOS logic...

This is an unusual design in that it uses plain metal gate CMOS logic instead of the usual PIC or a custom chip. The 22uF capacitor charges up during one half of the ac cycle, and supplies trigger current to the triac on both halves...

An electronic speed control for an AC Motor can be designed with a Light Dimmer IC by limiting the minimum firing angle of the triac so that the motor wont stall. This can be done effectively for high volume applications by making a minor change to the IC. An alternative to modifying the IC is illustrated in Figure 2...

In the circuit of Figure 1, assume that a brush-type dc motor must drive a load back and forth between two endpoints on a lead screw. Optical sensors determine end of travel, and an SPDT switch selects to which end to send the load. The sensors themselves supply all the necessary directional logic, and a triac powers the motor with the necessary polarity of half-wave pulses from the 13.5V-ac input...

Virtually all domestic and professional dimming systems are based on triacs. These devices will conduct once they have been fired, only while current flows in excess of the holding current of the device. These dimmers work very well with a resistive load such as an ordinary Tungsten filament light bulb as the triac can be fired at any point during the mains half-cycle and will continue to conduct until very close to the end of the half-cycle as current is drawn continuously over this period. In this way the lamp current can be adjusted from maximum to zero...

This circuit demands a control current that is 100 times smaller than that needed by a typical optically isolated solid state relays. It is ideal for battery-powered systems. Using a combination of a high current TRIAC and a very sensitive low current SCR, the circuit can control about 600 watts of power to load while providing full isolation and transient protection...

An opto-triac is the easiest way. Digi-Key sells them for 1-2 bucks apiece. The sensitivity is in the 5-25mA range, but you could probably coax the 8255 to *sink* that much (ie, drive the internal LED between +5v and the IC pin; to turn on, write-out a zero). Put a 220 ohm resistor in series with the LED...

Here is a low-cost circuit of Christmas star that can be easily constructed even by a novice. The main advantage of this circuit is that it doesnt require any step-down transformer or ICs. Components like resistors R1 and R2, capacitors C1, C2, and C3, diodes D1 and D2, and zener ZD1 are used to develop a fairly steady 5V DC supply voltage that provides the required current to operate the multivibrator circuit and trigger triac BT136 via LED1. The multivibrator circuit is constructed using two BC548 transistors (T1 and T2) and some passive components. The frequency of the multivibrator circuit is controlled by capacitors C4 and C5 and resistors R3 through R7...

A flashing LED is an excellent visual alarm. Unfortunately, the LED is a dc device and requires additional circuitry to operate from an ac source. Several circuits can perform the necessary function, but the circuit in Figure 1a is the most efficient. This circuit is also reliable, compact, and inexpensive. The F336HD red-flashing LED (part no. 276-036 at Radio Shack) operates directly from 5V and produces a consistent pulse of light at approximately 1 Hz without a time-constant capacitor. This LED starts immediately when you apply power and is insensitive to temperature variations. The W04G full-wave bridge rectifier produces a full-wave dc waveform from the 120V-ac line...

In the circuit of Figure 1, assume that a brush-type dc motor must drive a load back and forth between two endpoints on a lead screw. Optical sensors determine end of travel, and an SPDT switch selects to which end to send the load. The sensors themselves supply all the necessary directional logic, and a triac powers the motor with the necessary polarity of half-wave pulses from the 13.5V-ac input...