JN Lygouras, University of Thrace writes:
The control circuit in Figure 1a allows you to manually adjust the power delivered to a load. By changing the setting of potentiometer R3, you change the phase angle at which the thyristor (Q3) fires (Figure 1b), thereby altering the load current’s duty cycle. The adjustment range is about 0 to 180°. Q3’s off time is linear with R3, but of course the resulting load power is not linear with R3.
555 timer triggers phase-control circuit - [Link]
Test Thyristor and Triac using this circuit. Pay attention on mains voltage!
Thyristor – Triac Tester - [Link]
With this tool you can test various electronic components like diodes, LEDs, all kinds of transistors (PNP, NPN, several types of MOSFETs), capacitors, resistors as well as triacs and thyristors. It will show you several physical characteristics after the test was completed, like forward voltages, (gate) capacity and amplification factor. More over, it will show the polarity of the component and identifies the several pins of a package. A very nice and sophisticated project I host for Markus Frejek. I’ve done an additional layout for the device you can see on the left side. This project has found a lot of fans, including myself. The device is powered by an AVR ATmega 8 MCU.
Component tester - [Link]
After our recent post about the commercial semi-conductor tester we started a discussion about building a similar open source project. What came up is this AVR based transistor tester (machine translation) by Markus.
It’s built around an ATmega8 IC that interfaces with a standard HD44780 16×2 character LCD. The circuit that does the testing is simplicity itself. Three pairs of resistors are connected to 6 pins of the microcontroller, and each pair is connected on the other end to one of the transistor pins.
The theory of operation is also relatively simple. The microcontroller cycles through different patterns on its output pins until a recognizable pattern is read on its input pins. It supports a very large range of devices:
- NPN and PNP bipolar junction transistors.
- P and N channel, enhanced and D type mosfet transistors.
- P and N channel JFET transistors.
- Common anode and common cathode dual diodes.
- Two diodes in connected in anti-parallel or series configuration.
- Single diode.
AVR-based transitor tester - [Link]