This is an improved version of Anthony Smith’s designs for a latch on/latch off switch (see the whole series below). The new design switches a 120VAC load, and includes several much-needed details on ...

Figure 1a shows a latching circuit based on an optocoupler, IC 1. If the off switch remains closed, pressing the on switch powers the LED in the optocoupler. Thus, the transistor in IC 1 turns on. You ...

Push to make switch (PTM) is a momentary switch that closes the circuit only while pressed and is commonly used in doorbells and keyboards. Single pole, single throw switch (SPST) is a latching switch ...