Tag Archives: 220V

Inverter Circuit For Soldering Iron

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Here is a simple but inexpensive inverter for using a small soldering iron (25W, 35W, etc) In the absence of mains supply. It uses eight transistors and a few resistors and capacitors. Transistors Q1 and Q2 (each BC547) form an astable multivibrator that produces 50Hz signal. The complementary outputs from… Read more »

Dual Relay Driver Board Circuit Schematic

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A simple and convenient way to interface 2 relays for switching application in your project. This relay driver boosts the input impedance with a regular BC547 NPN transistor (or equivalent). Very common driver. It can drive a variety of relays, including a reed-relay. Transistor Q1and Q2 are a simple common-emitter… Read more »

3.3 V or 5 V Direct from the Mains

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The SR03x range of voltage regulator chips from Supertex (http://www.supertex.com) connects directly to the rectified mains supply and provides a low-current 3.3 V or 5.0 V output without the need for any step-down transformer or inductor. The circuit requires a full-wave rectified mains voltage input (waveform a). A built-in comparator… Read more »