A thyristor is any semiconductor switch with a bi-stable action
depending on p-n-p-n regenerative feedback. Thyristors are nor-
mally two- or three-terminal devices for either unidirectional or bi-
directional circuit configurations. Thyristors can have many forms,
but they have certain commonalities. All thyristors are solid state
switches that are normally open circuits (very high impedance),
capable of withstanding rated blocking/off-state voltage until trig-
gered to on state. When triggered to on state, thyristors become a
low-impedance current path until principle current either stops or
drops below a minimum holding level. After a thyristor is triggered
to on-state condition, the trigger current can be removed without
turning off the device. Thyristors are used to control the flow of
electrical currents in applications including:
• Home appliances (lighting, heating, temperature control, alarm
activation, fan speed)
• Electrical tools (for controlled actions such as motor speed, sta-
pling event, battery charging)
• Outdoor equipment (water sprinklers, gas engine ignition, elec-
tronic displays, area lighting, sports equipment, physical fitness)
Teccor's sensitive gate triacs are AC bidirectional silicon
switches that provide guaranteed gate trigger current levels in
Quadrants I, II, III, and IV. Interfacing to microprocessors or other
equipment with single polarity gate triggering is made possible with
sensitive gate triacs. Gate triggering currents of 3 mA, 5 mA,
10 mA, or 20 mA may be specified.
Teccor's sensitive gate SCRs are silicon-controlled rectifiers repre-
senting the best in design, performance, and packaging techniques
for low- and medium-current applications.
Anode currents of 0.8 A to 10 A rms can be controlled by sensitive
gate SCRs with gate drive currents ranging from 12 µA to 500 µA.
Sensitive gate SCRs are ideally suited for interfacing to integrated
circuits or in applications where high current load requirements and
limited gate drive current capabilities exist. Examples include igni-
tion circuits, motor controls, and DC latching for alarms in smoke
detectors. Sensitive gate SCRs are available in voltage ratings to
600 V ac.
Teccor's SCR products are half-wave, silicon-controlled rectifiers
that represent the state of the art in design and performance.
Load current capabilities range from 1 A to 70 A rms, and voltages
from 200 V to 1000 V may be specified to meet a variety of appli-
Because of its unidirectional switching capability, the SCR is used
in circuits where high surge currents or latching action is required.
It may also be used for half-wave-type circuits where gate-con-
trolled rectification action is required. Applications include crow-
bars in power supplies, camera flash units, smoke alarms, motor
controls, battery chargers, and engine ignition.
Surge current ratings are available from 30 A in the TO-92 packag-
ing to 950 A in the TO-218X package.
Sensitive gate triacs are capable of controlling AC load currents
from 0.8 A to 8 A rms and can withstand operating voltages from
200 V to 600 V.
Teccor's triac products are bidirectional AC switches, capable of
controlling loads from 0.8 A to 35 A rms with 10 mA, 25 mA, and
50 mA IGT in operating Quadrants I, II and III.
Triacs are useful in full-wave AC applications to control AC power
either through full-cycle switching or phase control of current to the
load element. These triacs are rated to block voltage in the “OFF”
condition from 200 V minimum with selected products capable of
1000 V operation. Typical applications include motor speed con-
trols, heater controls, and incandescent light controls.
Quadrac devices, originally developed by Teccor, are triacs and
alternistor triacs with a diac trigger mounted inside the same pack-
age. These devices save the user the expense and assembly time
of buying a discrete diac and assembling in conjunction with a
Teccor manufactures 15 A to 25 A rms rectifiers with voltages
rated from 200 V to 1000 V. Due to the electrically isolated TO-220
package, these rectifiers may be used in common anode or com-
mon cathode circuits using only one part type, thereby simplifying
Diacs are trigger devices used in phase control circuits to provide
gate pulses to a triac or SCR. They are voltage-triggered bidirec-
tional silicon devices housed in DO-35 glass axial lead packages
and DO-214 surface mount packages.
Diac voltage selections from 27 V to 45 V provide trigger pulses
closely matched in symmetry at the positive and negative break-
over points to minimize DC component in the load circuit.
Some applications include gate triggers for light controls, dimmers,
power pulse circuits, voltage references in AC power circuits, and
triac triggers in motor speed controls.
The Quadrac is offered in capacities from 4 A to 15 A rms and volt-
ages from 200 V ac to 600 V ac.
Sidacs represent a unique set of thyristor qualities. The sidac is a
bidirectional voltage triggered switch. Some characteristics of this
device include a normal 95 V to 330 V switching point, negative
resistance range, latching characteristics at turn-on, and a low on-
state voltage drop.
The Teccor alternistor is specifically designed for applications
required to switch highly inductive loads. The design of this special
chip effectively offers the same performance as two thyristors
(SCRs) wired inverse parallel (back-to-back).
This new chip construction provides the equivalent of two electri-
cally-separate SCR structures, providing enhanced dv/dt charac-
teristics while retaining the advantages of a single-chip device.
One-cycle surge current capability up to 20 A makes the sidac an
ideal product for dumping charged capacitors through an inductor
in order to generate high-voltage pulses. Applications include light
controls, high-pressure sodium lamp starters, power oscillators,
and high-voltage power supplies.
Teccor manufactures 6 A to 40 A alternistors with blocking voltage
rating from 200 V to 1000 V. Alternistors are offered in TO-220,
TO-218, and TO-218X packages with isolated and non-isolated
©2002 Teccor Electronics
Thyristor Product Catalog(972) 580-7777