by Anthony Smith @ edn.com:
The simple current-limiting load switch shown in Figure 1 will be familiar to most readers. In this circuit, a high level signal applied to the input switches on MOSFET Q2, which energizes the load. The load current is limited by negative feedback applied via Q1.
Load switch with self-resetting circuit breaker – [Link]
by Vadim Panov:
Back when I was only starting to dabble in electronics, I needed a project that would meet the following requirements:
simple to make;
original (i.e. done entirely by myself from scratch);
containing a microcontroller;
and maybe the most important of all, useful. I’ve had enough devices I assembled just to dismantle the whole thing a month later.
The thing I came up with at the time was a light swich for my room controlled over an IR remote from TV. Remote that I had used RC-5 protocol, hence the firmware is suited for any RC-5 compatible remote.
Everyone is familiar to the everliving problem with switching the lights off in your room before going to bed and stumbling back across the room. The IR switch I describe here solves that problem, and I can definitely tell that this project was a success – I am still using it with no regret.
Infrared remote controlled light switch with ATTiny2313 – [Link]
Pleasant actuation characteristics and reliable features of a push button switch Marquardt series 1840 make it attractive for all applications where you require control by a push.
Classic push-button switches are favorite for many decades, maybe also because they´re well known already from the beginnings of electronics. Probably, a nostalgia is not the only reason making them popular, but mainly an easy control, when even an unacquainted person knows, that it´s something “what has to be pushed” to change a status of an electric device.
Exactly a term “to change a status” is important, because at these switches it´s not possible (or not easily visible), whether it´s switched on or off. Though it´s true, that the majority of such switches is a little bit pushed down (lowered) in a switched on status, but the difference is often small. That´s why these switches are not suitable for applications, where from safety reasons it´s necessary to know tha status of the switch before connecting to a mains line.
Switch 1841.1301 (SPNC) belongs to a top in this segment and offers a really pleasant control and a quality switching system with a mechanical endurance of min. 100 000 cycles. 6A/ 250V is far sufficient for many applications and assembly is simple – by means of an M12 nut supplied. An interesting supplement is also a neoprene cap integrated with an M12 nut, enabling to gain a considerable resistance to water and dust. Also available are 2-pole versions – 1842 and also versions functioning as a push-button (momentary).
There are 2 nuts supplied. One is “regular” – hexagonal and the other one is a round type intended to be used as a top cover on a front panel. Further detailed information will provide you the Marquardt 1840 datasheet.
Marquardt 1841 – above standard classics – [Link]
Whether it´s necessary to operate a device in gloves, or you only wish the given push-button was sufficiently big and well visible, new series of round and square caps for series Multimec 5G will solve it.
Well known Dutch producer of top quality switches – company MEC, comes with novelties in a form of relatively big caps for a universal series of push buttons Multimec 5G (lifetime of 10 million cycles).
Series 5G is exceptional by the fact, that it can by equipped by a huge amount of caps of various sizes, shapes and colors. In result, you might even not say, that beneath so different push-buttons” (caps), still the same push-button switch is used.
The latest addition to the family of caps for the 5G push buttons is:
● 10R/10RF/10RM – round 30mm caps. 10R has a slightly curved surface, 10RF has a flat surface and sharp edges, and the 10RM has a metal plate with an illuminated legend.
● 10Q/10QM – square 22mm caps. 10Q has a flat surface, 10QM has a metal plate with a illuminated legend.
Multimec 5G push-buttons operate with these caps reliably – independently on the place of pressing the button (in the middle/ on the edge). Both series have optional accessory – sealing enabling to reach IP67 and a plastic spacer. Need for a spacer depends on the front panel thickness (into which a push-button is built-in) and on the overall design of a device. Overall building height is only 11mm and they´re intended to be placed in almost one level with a front panel, resulting in a very elegant look.
Homogenous illumination (backlight) of these big caps can be easily reached by means of 4 small LEDs placed on a PCB around a push-button. This also gives a possibility to freely use various LED according to your choice and to use their color combinations – for example for indication of a device status. As a standard, 7 solid colors are available and 1 transparent “frost ice” white for illumination.
Recently, we also added many other caps and push buttons from company MEC into our offer. All new additions can be found below this article.
New MEC switches can be seen even from afar – [Link]
Clap switch/Sound-activated switch designed around op-amp, flip-flop and popular 555 IC. Switch avoids false triggering by using 2-clap sound. Clapping sound is received by a microphone, the microphone changes the sound wave to electrical wave which is further amplified by op-amp.
555 timer IC acts as mono-stable multi-vibrator then flip-flop changes the state of output relay on every two-clap sound. This can be used to turn ON/OFF lights and fans. Circuit activates upon two-clap sound and stays activated until another sound triggers the circuit.
Sound Activated Switch – [Link]
The Project works as electronic toggle switch. The circuit is based on CMOS CD4013 Flip Flop IC, The circuit has two stable states, ON and OFF. Once it is ON, it remains ON till you press the switch again. A short button press of a tactile switch SW1 latches the circuit ON and another toggles it back OFF. Relay switch contacts can handle high AC Voltage as well as High DC current, this makes the project suitable for application like ON/OFF Fan, Light, TV, Pump, DC Motor, any electronic project required electronic toggle operations and few other devices work on AC voltage up to 250V AC or DC current up to 5Amps.
Electronic Toggle Switch – [Link]
Dhananjay Gadre & Nidhi Sharma writes:
Microcontrollers, the heart of all modern electronic gadgets, are increasingly powered with sub-5V power supplies. This complicates the control of external loads powered by higher voltages. The reduced I/O supply voltage leads to increased complexity in handling high-side voltage switching. Figure 1 illustrates the conventional solution for controlling a 5V high-side switch, driven here by a 3.3V signal.
Zener level-shifter drives high-side switch – [Link]
by brmarcum @ instructables.com:
I hate Christmas tree lights.
Well not really, I just don’t enjoy having to climb under the tree every time I want to plug in or unplug the lights. In the interest of saving my sanity, I decided to build a motion activated switch that can power the lights for me. It has an integrated adjustable timer so they will stay on for as long or as short as I want. Here’s a video showing the final test on the fish tank light.
Motion Activated AC Switch – [Link]
App note from International Rectifier on their IR331x part which offers a bunch of power protection and control all in one chip. [via]
The new IR331x devices designed in P3 technology provide more accuracy of the current feedback. The IR331X devices suit for any application where the load current sensing is required. IR331X is fully protected: programmable current shutdown, over temperature shutdown and reverse battery protection. The current sensing features offer current readout accuracy, high frequency bandwidth, a versatile way to control the current shutdown and replaces the shunt resistor.
App note: Current sensing high side switch – [Link]
nevdull @ instructables.com writes:
Tactile switches (a specific type of momentary switch) are everywhere and they are especially popular on DIY electronics and microcontroller boards because they are well suited to act as a boot option or reset switch. Particularly, momentary switches are switches that don’t save their state when you depress the switch. That is, when you push the switch (and while you have the switch depressed) the circuit is ON, but once you let off the switch it reverts back to OFF.
Use a Momentary or Tactile Switch as a Pushbutton Switch – [Link]