Matt circuit

Certain industrial controls require accurate switching operations. For example, in case of a foot-switch for precise drilling work, even a small error in switching may cause considerable loss. This low-cost but accurate foot-operated switch can prevent that. IC NE555 is wired in one-shot mode. Its output pin 3 goes high only when both switches S1 and S2 are pressed simultaneously. You can release any one of the switches without changing the output state. When you release both the switches, the output goes low. Simple Accurate Foot-Switch Circuit Diagram The switches are placed under a foot paddle as shown in Fig. 2. LED1 is used as a warning indicator. If either S1 or S2 gets pressed erroneously, LED1 blinks to warn the operator. The operator can then withdraw his foot in case of a mistake or depress the other switch also to trigger the circuit. LED1 is to be mounted on the operator’s desk. The circuit operation is simple. Resistors R2, R3 and R4 form a voltage divider. IC NE555 has tw...

This simple circuit shown int the schematic diagram actives the switch using sound. We can use this circuit for various applications, such as automatic (sound-controlled) disco light or car’s LED light show.  The Q1 amplify the audio from mic. The R1 is used to adjust the peak of signal to greater than about 0.7 volts, act as sensitivity adjuster. A certain level, the signal coming from microphone, after amplification by Q1, will trigger the SCR and light lamp I1. If we change the lamp with a relay, then we can get a sound-activated relay/switch, which can be used to control more powerful / high wattage high voltage lamps. Sound Activated Lamp-Relay Switch Circuit Diagram If we use a relay, place a 1N4007 diode in parallel with the relay coil to prevent the back-emf from  relay coil destroying the SCR.

The essence of the circuit is for the input of tone and signal to provide an activation for the relay switch. Relay – an electrically operated switch where the current flowing through the coil of the relay is creating a magnetic field which attracts a lever and changes the switch contacts, thereby making its state open or close BC214 – a complementary silicon planar epitaxial transistor used in AF small signal drivers and amplifiers as well as for low noise preamplifier applications due to its feature of good linearity of DC current gain LM741 – a general purpose single operational amplifier with features such as offset null, compensated internal frequency, voltage range with high input, good stability of temperature, and protected from short circuit The use of relay will allow the circuit to switch from one condition to another. It can also be referred to as a form of an electrical amplifier since it is able to control an output circuit of higher power than the input circuit. There ar...

The SMPS described here is suit-able for high-wattage stereos and other similar equipment. The circuit employs two high-voltage power transistors (BU208D) which have built-in re-verse-connected di-odes across their collectors and emitters. It can supply about 250-watt out-put. The circuit uses a ferrite core transformer of 14mm width, 20mm height, and 42mm length of E-E cores. An air gap of 0.5 mm is required between E-E junction. Good insulation using plastic-insulating sheets (Mylar) is to be maintained between each layer of winding.  Switch Mode Power Supply Circuit Diagram The number of primary turns required is 90 with 26 SWG wire. The secondary winding employs 17 SWG wire (for 4A load current). Each turn of the secondary develops approximately 2 volts. The reader can decide about the output volt-age and the corresponding secondary turns, which would work out to be half the desired secondary voltage. The volt-age rating of capacitors C7 and C8 should be at least twice the seco...

AC switches are silicon devices that control AC loads directly connected to the AC mains. This means that the driving reference terminal of the AC switch can be connected to the Line potential. This circuit explains the need of an insulation layer for the control unit and the way to implement it for an AC switch device.  It was thought in the past that connecting an MCU to the Line should be avoided as it will lead to poor appliance immunity. But it has been demonstrated over the years that such topology provides good immunity. Connecting an MCU supply to a stable non-floating reference is even better for immunity. Safety insulation should be provided between accessible parts and high-voltage circuits to protect end users against electric shocks. It’s not required to ensure safety insulation by insulating low-voltage control circuits (like MCU) from high-voltage parts (like AC switches). In fact, the insulation could be implemented elsewhere—for example, on the keyboard to which the e...

This circuit switches a printer’s USB connection from a PC to a laptop. What was needed was a method of allowing a laptop to use the printer occasionally while at all other times the printer would be connected to the PC. Instead of unplugging the printer from the PC and then into the laptop, the circuit switches the USB connection automatically. K1 and K2 are standard type-B USB sockets, while K3 is a USB type-A socket. The USB lead from the laptop plugs into K2 while the PC’s USB lead plugs into K1. A USB cable from K3 connects the printer to this circuit. The cable from the PC is always plugged in while the cable from the laptop is only connected whenever this device needs to print. In normal operation the laptop is not connected to K2, so the USB signal to the printer comes from the PC via K1, the normally closed contacts of relay Re1, through to K3 and from there to the printer. Circuit diagram: USB Printers Switch Circuit Diagram Whenever the laptop is connected up, the presence o...

In recent years, the use of switch mode power supply (SMPS) has become more comon as more applications demand for greater power eficiency. It makes use of semiconductor (mostly MOSFET) fast switches to switch DC input that has been rectified at high frequency. The advantages of high frequency switching are that it reduces the size of inductor, capacitors & transformer used. Other advantages of switching power supply over linear power supply are : 1) High Efficiency (up to 90% and above for nice design). 2) Output can be higher than input. 3) Able to operate over a variety of input power supply. 4) Able to have over output. The setback of using SMPS compared to linear power supply is that it generates electrical noise which contributes to electromagnetic compatibility design issues & more part count. Buck Converter SMPS The SMPS circuit below from Power Integration makes use of LNK304 as its high frequency switch. Take note that this circuit is non isolated type which means tha...

AC Mains Bistable Switch Circuit Diagram. This AC mains-operated bistable  switch turns on or turns off a  device using a miniature neon  lamp and a few discrete components.  This switch can be used for control pan-els, appliances and lighting controls.  A push-to-on switch is used to  light up the neon lamp. The light emit-ted by the neon lamp, in turn, enables  the switching action of the circuit. Use  of a 555 timer wired for bistable operation makes the circuit act as a bistable  switch. . AC Mains Bistable Switch Circuit Diagram AC Mains Bistable Switch Circuit Diagram   The neon lamp (NL1) and the  push-to-on switch (S1) are directly connected to 230V AC mains. The 12V DC  supply for timer 555 (IC1) is derived  from 230V AC mains through capacitive dropper C1, resistor R1 and a 12V  zener diode. IC1 works as a flip-flop  circuit, with the signal at its output  pin 3 toggling every time it receives a...

It would be nice and comfortable doing our work and what we needed are readily available to save time and effort. It lessens the hassle of looking for missing pieces or even using multiple devices to check the accuracy and effectiveness of the equipments we are using. Just like this switch box that has a capacitor and resistor in one unit. It will be easier and faster to check the capacitance and resistance by switching the knobs. This device may look old-fashioned but can really come very handy. This is simple and not that expensive to make and very useful in electronic projects or for the purpose of collecting devices for future use.

This is a simple Battery Switch With Low-Dropout Regulator Circuit Diagram. In the form of the LT1579 Linear Technology (www.linear-tech.com) has produced a practical battery switch with an integrated low-dropout regulator. In contrast to previous devices no diodes are required. The circuit is available in a 3.3 V version (LT1579CS8-3.3) and in a 5 V version (LT1579CS8-5), both in SO8 SMD packages. There is also an adjustable version and versions in an SO16 package which offer a greater range of control and drive signals. The main battery, whose terminal voltage must be at least 0.4 V higher than the desired output voltage, is connected to pin IN1. The backup battery is connected to pin IN2. The regulated output OUT can deliver a current of up to 300 mA. The LDO regulator part of the IC includes a pass transistor for the main input voltage IN1 and another for the backup battery on IN2. The IC will switch over to the backup battery when it detects that the pass transistor for the main ...

Fig.1 Precision Light- Sensitive Switch Circuit Diagram:   In Fig. 1 see a precision light- sensitive switch that activates when the sensed quantities go above or below pre-set values. The LDR can be any cadmium sulfide unit that has a resistance in the range 500R to 20k at the required trip level. The RV1 adjust LDR at normal light level. Fig. 2 Differential Temperature Switch Circuit Diagram: In Fig. 2 see a differential temperature switch circuit using ordinary silicon diodes as temperature sensing elements and responding to differentials of a fraction of degree. RV2 can be used to apply an effective offset of several degrees to the two diodes. To adjust the circuit, apply the required differential temperature to the diodes and then adjust RV2 so that the relay just turns on. The circuit responds to the relative temperatures, rather than the absolute temperatures, of the two diodes. Part List : R1=LDR *see text R2-3=10Kohm R4=2.2Kohm R5-6-7-10=4.7Kohm R8-9=2.7Kohm RV1=22Koh...

Only simple materials and a little bit of skill are needed to build an RS232 switch. All that you need are two 9-way sub-D plugs with solder pins, a small piece of sheet aluminium, two sets of screw retainer posts, a 4-pole double-throw switch, a strain relief sleeve and a suitable plastic connector shell for a 25-way sub-D connector, with both in-line and right-angle cable entries (such as Conrad Electronics #711322). What is important is that the side cable entry together with its associated strain relief leaves enough room for the switch. If necessary, you may have to cut away a few square millimetres of the sidewall or a few ribs of the plastic shell.   Project image :   Mini RS232 Data Switch Image   The switch is operated via the in-line cable opening, as can be seen from the photo. A suitable switch with an overall length of 29 mm can be found in the Conrad catalogue under order number 708232. The only modification that must be made to the connector shell is to drill two ...

Nowadays the batteries are gaining more and more power, being the only components that fail to provide energy for portable electronic devices. The evolution is rapid, leading manufacturers electronic equipment to attempt to minimize the consumption of their products so that they can operate for several hours using simple batteries trade. In spite of the efforts of manufacturers, the device will absorb a zero power not yet invented. Thus, both small and if the current device is mathematically certain that at some point, after a few hours, days or ethdomades, the battery-drain .  Automatic Switch for Batteries  Circuit diagram The purpose of the circuit will describe below, is to keep 'alive' batteries for the maximum time, minimizing unnecessary consumption. Taking a brief look at the circuit, you notice that the few parts that are can be integrated into any device powered by a battery of 9 V. The main trait is that allows current to flow to the load for a minute, since you pre...

The circuit of the cell phone-controlled audio/video mute switch . This cell-phone-controlled audio/ video mute switch is highly useful in automobiles. The circuit automatically disconnects power supply to the audio/video system whenever the mobile handset is lifted off the holder for making or receiving a call. You can use any readily available cell-phone holder with some mi-nor alterations or fabricate it yourself as shown in Fig. 1.  Fig. 1: Proposed cell-phone holder   The circuit is wired around IC LM555 (IC1), the CMOS version of timer NE555, as shown in Fig. 2. IC1 is used as a medium current line driver with either an inverting or non-inverting output. It can sink (or source) current of up to 50 mA only, so take care while handling it. The audio/video system is connected to the circuit via normally opened (N/O) contacts of the relay.   Fig. 2: The circuit of the cell phone-controlled audio/video mute switch   When the cell phone is in its holder, LDR1 does ...

This is a Simple Sixteen Way Clap-Operated Switch Circuit Diagram . Control your home appliances without getting out of your bed. You just have to clap in the vicinity of the microphone used in this circuit, which you can keep by the bedside. You can switch on/off up to four different electrical equipment (TV, fan, light, etc) in 16 different ways.This circuit is built around timer IC 555 (IC1), CMOS IC 74LS93 (IC2) and five BC547 npn transistors (T1, T2, T3, T4 and T5). Transistor T1 is used as the preamplifier and the rest are used for driving the relays. Sixteen Way Clap-Operated Switch Circuit Diagram   A small condenser microphone is connected at the base of transistor T1, which is biased from resistor R1 (10 kilo-ohms). The clapping sound is converted into electrical energy by the microphone and amplified by transistor T1. The transistor output is fed to the monostable circuit wired around IC 555. Output pin 3 of the timer is connected to the clock input of divide-by-16 ...

This circuit allows an SPST momentary pushbutton to act as a push-on push-off switch, using a DPDT latching (bi-stable) relay. It was originally intended to allow a single pushbutton switch on the dash of a vintage car to provide a latched function. The relay only draws current when it is being switched. At other times, the only current drain on the 12V supply is the leakage current of one 22µF capacitor, which is very low. It works as follows. Assume that initially the latching relay is in the reset state, with pins 4 and 6 connected together. In this state, C2 charges up to +12V via 2.2kO resistor R2 while capacitor C1 remains discharged as it is not connected to the 12V supply. If S1 is pressed, C2 discharges via the relay’s “set” coil, diode D2 and S1. This switches the relay into its set position, connecting pins 4 and 8. C1 then begins to charge via R1. While S1 is being held down, the relay does not return to the reset position because the current supplied via R1 is insufficient...

In order to control electrical loads such as heating in the picture below using double pole switch. Double pole switch consists of four terminals. And electric heating load consists of three terminals. In the second switch terminal to get into each phase line (L) and the neutral line (N). While the other two terminals each connected to two terminal heating load. One other terminal on the body burden, directly connected to the grounding line.  a. Electrical circuit drawings double pole switch b. Double pole switch wiring drawings c. Image channel double pole switch

In the form of the LT1579 Linear Technology (www.linear-tech.com) has produced a practical battery switch with an integrated low-dropout regulator. In contrast to previous devices no diodes are required. The circuit is available in a 3.3 V version (LT1579CS8-3.3) and in a 5 V version (LT1579CS8-5), both in SO8 SMD packages. There is also an adjustable version and versions in an SO16 package which offer a greater range of control and drive signals. The main battery, whose terminal voltage must be at least 0.4 V higher than the desired output voltage, is connected to pin IN1. The backup battery is connected to pin IN2. The regulated output OUT can deliver a current of up to 300 mA. The LDO regulator part of the IC includes a pass transistor for the main input voltage IN1 and another for the backup battery on IN2.  Battery Switch With Low-Dropout Regulator circuit Diagram The IC will switch over to the backup battery when it detects that the pass transistor for the main voltage input ...

A water pressure switch is designed for sensing pressure of an incoming water flow from a source which may be a booster pump, and compare it with the water pressure inside the tank which is being filled by the booster pump water flow. When the water pressure inside the tank crosses the set threshold relative to the pump pressure, an in-built switch is tripped. The trip switch is configured with the booster pump electrical such that when it trips, the motor halts and prevents the tank from filling above the desired upper threshold. A reverse action is initiated as soon as the water level in the tank reaches below a certain lower threshold. Pressure switches are normally mechanical with their operations, and may not be easy to build or replicate at home by a hobbyist. Even an electronic equivalent of the same which might require a precise pressure sensor could be difficult to implement due to the many intricacies of the system. However a simple alternative for fulfilling the above...