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Description

The circuit presented below employs a double-pole, double-throw relay alongside a single transistor to facilitate the switching of the relay using a momentary push button. One set of relay contacts is utilized for controlling the load, while the other provides feedback to ensure the relay remains either activated or deactivated. Multiple push buttons can be connected in parallel to enable relay toggling from various locations. The deactivated state is characterized by the relay contacts configured such that the 1000 uF capacitor accumulates a voltage of approximately 2.7 volts. Upon actuation of the switch, the capacitor’s voltage is applied to the transistor’s base via a 560 resistor, triggering transistor conduction and subsequently activating the relay. In the activated state, the relay contacts are arranged to enable a continuous current flow through the 3.3K resistor and 560 ohm resistor, maintaining the transistor’s active state. During this activated condition, the capacitor discharges fully to zero through the 1K resistor. When the switch is re-closed, the capacitor induces a voltage change that moves the transistor base towards ground, deactivating the relay.

More about components

A 2N3053 transistor was chosen for this circuit. This NPN bipolar junction transistor is a general-purpose transistor commonly utilized in switching and amplification applications. Its features include a moderate current gain and a relatively low collector resistance, making it suitable for a variety of electronic circuits. The 2N3053 is a robust and reliable component, frequently found in both hobbyist and professional projects.

Circuit diagram