Switch


Relay Toggle Switch

I designed this relay circuit to function as a DPDT toggle which is controlled by a momentary switch. I strive to keep my circuits simple with little or no integration (555’s, transistors, etc). The circuit is shown active or “on” mode. Half of RL1 and RL2 manipulate the switching and the other is connected to […]


Electronic Touch Switch

Mechanical contacts have the disadvantage that they wear out. That is why it is practical to use an electronic ‘touch switch’ in some situations. With such a touch switch the resistance of the human skin is used for the switching action. The schematic shows the design of a circuit that senses the resistance of the […]


Ultra-Sensitive Solid State Clap Switch

Here is the circuit of a highly sensitive clap switch that can be operated from a distance of up to 10 metres from the microphone. Signals picked up by the microphone are amplified by transistors T1, T2, and T3. Diode D1 detects clap signals and the resulting positive voltage is applied to the base of […]


Petrol Gas Switch For A Pajero

My current vehicle, a Pajero, was modified for dual fuel – ie, petrol and gas. However, it’s necessary to run the vehicle on petrol at regular intervals to stop the injectors from clogging up. This simple circuit allows the vehicle to be started using petrol and then automatically switches it to gas when the speed […]


Mains Remote Switch

This compact design forms a remotely operated switch that receives its control signal via the mains voltage. The switch is operated using the ‘mains remote transmitter’ described elsewhere in this issue. With this transmitter, a switch should be connected between pins 1 and 2 of K1. Depending on the application, this must be either a […]


Heat Sensitive Switch

At the heart of this heat-sensitive switch is IC LM35 (IC1), which is a linear temperature sensor and linear temperature-to-voltage converter circuit. The converter provides accurately linear and directly proportional output signal in millivolts over the temperature range of 0°C to 155°C. It develops an output voltage of 10 mV per degree centigrade change in […]


Master/Slave Switch

In this age of enlightenment any sort of relationship that could be described as master/slave would be questionable but for the purposes of this circuit it gives a good idea of how it functions. The circuit senses mains current supplied to a ‘master’ device and switches ‘slave’ equipment on or off. This feature is useful […]


Proximity Switch

This circuit is for an unusually sensitive and stable proximity alarm which may be built at very low cost. If the negative terminal is grounded, it will detect the presence of a hand at more than 200mm. If it is not grounded, this range is reduced to about one-third. The Proximity Switch emits a loud, […]


Circuit Project: 12V Touch Switch Exciter

This circuit is designed to generate a 20KHz pseudo sine wave signal that can power about 50 remote touch activated switch circuits. It can support a cable length of about 2500 feet. A typical remote switch circuit is also shown as well as a receiver circuit for those switches. Circuit diagram Source: DiscoverCircuits


Keyboard/Mouse Switch Unit

Unplugging or re-connecting equipment to the serial COM or PS2 connector always gives problems if the PC is running. Even if you only need to swap a mouse or changeover from a graphics keyboard to a standard keyboard. The chances are that the connected equipment will not communicate with the PC, it will always be […]