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Presettable times for train stops in stations are indispensable if you want to operate your model railway more or less realistically according to a timetable. This circuit shows how a 555 timer can be used with a relatively small timing capacitor to generate very long delay times as necessary by using a little trick (scarcely known among model railway electronic technicians): pulsed charging of the timing net-work. Such long delays can be used in hidden yards with through tracks, for instance.  As the timer is designed for half-wave operation, it requires only a single lead to the transformer and one to the switching track or reed contact when used with a Märklin AC system (H0 or H1). The other lead can be connected to any desired grounding point for the common ground of the track and lighting circuits. Circuit diagram : Long-Delay Stop Switch Circuit Diagram As seen from the outside, the timer acts as a monostable flip-flop. The output (pin 3) is low in the quiescent state. If a ...

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 am1 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 freq uency, 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 are man...

Let me ask this simply, then explain my use case below. This is a Easy Line Activated Solid State Switch Project . Each and every time a phone on the same line or calling numberis taken off-hook, the circuit will be activated to control an external electronic circuit. If several extension telephones are used on one phone line, the circuit can be useful as a busy indicator. LEDl contains a special flashing red LED that makes an excellent indicator for a busy circuit condition.   Line Activated Solid State Switch Project Circuit Diagram The solid-state switch can be used for several other phone-activated applications, such as automatically turning on a cassette recorder, starting a phone-use timer or counter, etc. A small relay can be connected at points A and B, in place of LEDl, to control external circuits. A 117-Vac-to-6-Vdc plug-in power supply can be substituted for the battery to keep the operating cost at a minimum.  The 48-Vdc, on-hook, phone-line voltage keeps Ql...

This is a simple Audio or voice Operated Switch Circuit Diagram. The sound picked up by SPKRl, which acts as a microphone, is fed to transistor amplifier Ql. The output of Ql is applied across coupling transformer T1 and is used to drive the gate circuit of Triac TRl. TRl is used to lend a latching effect to the action of the relay. Audio Operated Switch Circuit Diagram Sourced By: Circuitsstream

Description  In most countries it is now mandatory or at least recommended to have a rear fog light on a trailer with the additional requirement that, when the trailer is coupled to the car, the rear fog light of the towing car has to be off. The circuit shown here is eminently suitable for this application. The circuit is placed near the rear fog light of the car. The 12-V connection to the lamp has to be interrupted and is instead connected to relay contacts 30 and 87A (K1, K3). When the rear fog light is turned on it will continue to operate normally. Circuit Diagram:   If a trailer with fog light is now connected to the trailer connector (7- or 13-way, K2), a current will flow through L1. L1 is a coil with about 8 turns, wound around reed contact S1. S1 will close because of the current through L1, which in turn energizes relay Re1 and the rear fog light of the car is switched off. The fog light of the trailer is on, obviously. The size of L1 depends on reed contact S1. Th...

This is a light switch or light activated relay circuit .The relay on when LDR uncoverd and relay off when LDR covered .Adjust VR1 for light sensitive.LED will turn on at the same time with relay

The switch-disconnector or Isolator seitch is largely used as the main switch in low and high voltage switchgears for distribution of power, starting and stopping motors and isolating loads during maintenance. They are also enclosed in metal or plastic boxes as safety switches to ensure that accidental start of machines is prevented. The range from 16 to 160 Amp are either base plate or door mounted by snap-on or screw fitting. Front operated 3-, 4-, 6-, 8-pole and change over types are available as standard. From 200 up to 3150 Amp the switch-disconnectors, also called load break switches, are designed as pole modules and they are available as 1- to 4-pole versions, front or side operated. From 200 up to 3150 Amp the switch-disconnectors, also called load break switches, are designed as pole modules and they are available as 1- to 4-pole versions, front or side operated.

This circuit will provide an indication whenever the input voltage differs from two defined limits, V1 and V2. The limits are adjustable and the circuit made to trigger from the adjustable "window". Circuit Diagram: Notes: This circuit will provide an indication whenever the input voltage differs from two defined limits, V1 and V2. The supply voltage, Vcc must be higher than the highest input voltage by at least 2 volts. One application here is to monitor a 12V car battery. V1 could be set to 14V and V2 to 11V thus giving an indication of over charge or a weak battery. Please Note. Only pins 7 and 4 (power supply), pin 6 (output) and pins 2 and 3 (inverting and non-inverting inputs) are used. All other pins are not connected. The pinout for the CA3140 is shown below. The op-amps used here are MOSFET CA3140. They are used to advantage as they have very little output offset voltage and can switch down to near 0 volts. If any other op-amp is used such as LF351 or CA741 then it w...

Quite often, we forget to turn off the soldering iron. This results in not only a smoking oxidised iron but also waste of electricity. To solve this problem, here’s a circuit that automatically switches off the soldering iron after a predetermined time. The circuit draws no power when it is inactive. The circuit can also be used for controlling the electric iron, kitchen timer or other appliances. Automatic Soldering Iron Switch Circuit Diagram At the heart of the circuit is a monostable multivibrator built around timer IC 555. When the circuit is in sleep mode, to switch on the soldering iron, you should push switch S1 momentarily. The multivibrator gets triggered and its output pin 3 goes high for around 18 minutes to keep relay RL1 energised via transistor T1. At the same time, capacitor C3 charges and AC supply is provided to switch on the soldering iron via normally opened (N/O) contacts of relay RL1. The soldering iron remains ‘on’ for the time period predetermined by resistor R1...

The series of light switches this time slightly different from the voltage of work. The series of light switches can work directly on the AC power network. Light switches are using the main component of TRIAC and LDR. The circuit is very simple and the components were sold in the market. If you want a light reception sensitivity of this circuit can be arranged then the 3.3 MOhm resistor can be replaced with a variable resistor. For more details can be seen from the following series of images. Circuit Diagram With Triac Light Switch series is prisipkerjanya as dimers, but dimers control performed by the reception of light around the LDR. The lower the intensity cayaha received LDR then semkin bright lights. For installation LDR need to be considered so as not exposed to light from the lamp directly.

If it is desire to automatically energized and de-energized an electrical equipment at specific time of day, Automatically Time Switch (ATS) is use. One particular example is the switching of the street lights “ON” and “OFF” at 6:30 A.M. Control Operation The ATS has a disk D (A clock) which rotates 1 revolution for every 24 hours. The rotor scaled 24 hours at the ream. See figure (A). Each hour has a slot every 15 minutes interval. To this slot a white pin W and orange pin 0 can be inserted and detached. Both the orange pin and the white pin can be inserted in the slot with an indication of certain time. The time in the slot where the orange pin is inserted is the time desire to energize a certain machine. The white pin is inserted in the slot with the tome desired to de energized the machine. For example, in figure (A), it is desire to energize the street lights at 6:00 PM. An orange pin 0 is inserted into the slot with 18:00, (military time) indication. If the street lights are to...

Simple Remote on-off Switch Circuit Diagram . This circuit provides power control without running line-voltage switch leads. The primary of a 6-volt filament transformer is connected between the gate and one of the main terminals of a triac.   Simple Remote on-off Switch Circuit Diagram The secondary is connected to the remote switch through ordinary low-voltage line. With switch open, transformer blocks gate current, prevents the triac from firing and applying power to the equipment. Closingthe switch short-circuits the secondary, causing the transformer to saturate and trigger the triac. Sourced By circuitsstream

This simple Simple Mat Switch Circuit Diagram produces a warning beep when somebody crosses a protected area in your home or office. The switch, hidden be-low the floor mat, triggers the alarm when the person walks over it. The circuit uses a conductive foam as the switch. It can be two small pieces of conductive pads usually used to pack sensitive ICs as antistatic cover. Alternatively, you can make the switch by coating conducting carbon ink on two small pieces of a copper-clad board. Circuit diagram : Simple Mat Switch Circuit Diagram When the circuit is in standby mode, transistor T1 does not conduct, since its base is floating. When the person walks, the switch is pressed and current flows through R1 and the switch to provide positive bias to transistor T1. Transistor T1 conducts and its collector voltage drops, which acts as a negative trigger input for the monostable wired around IC NE555 (IC1). IC1 outputs a pulse of fifty-seconds duration with preset values of R4 and C3. This...

This simple device allows two computers to share a single USB printer or some other USB device, such as an external flash drive, memory card reader or scanner. A rotary switch selects the PC that you wish to use with the USB device, while two LEDs indicate the selected PC. The most common way to share a USB printer between two PCs is to use one machine as a print server. However, that’s not always convenient because it means that the server PC must always be on if you want to print something. Picture of the project: That can be a real nuisance if you just want to quickly fire up the other machine and print something out. It also means that the two PCs must be networked together, either via a hub/router or directly via an ethernet crossover cable. Another way is to use a dedicated USB print server. However, as before, this must be connected to an ethernet network, along with the PCs. Such devices also need their own power supply, generally cost well over $100 and are overkill if you jus...

This circuit acts like a two-position switch but is operated using a pushbutton. After power has been applied, the circuit is in the following initial state: the bases of T1 and T2 are at the positive supply potential and the base of T3 is at ground potential. All transistors are cut off. The other contact of the pushbutton is at ground potential. No current flows through the relay coil and the status LED is off.   Circuit Diagram : Pushbutton Switch Circuit diagram If the pushbutton is pressed, T2 and (after a slight delay due the RC network) T3 switch on. The collector of T3 is now nearly at ground potential, so current flows through the relay coil and the function LED is illuminated. T1 can also switch on. This situation is stable, since ground potential can reach the base of T2 via R1, so nothing changes when the pushbutton is released. C1 is charged via R3 to cause a positive potential to be present at the pushbutton. If the pushbutton is now pressed again, it connects a pos...

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.  Circuit diagram: Simple 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 ...

Heat Sensitive Switch Circuit Diagram . 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 the ambient temperature. Therefore the output voltage varies from 0mV at 0°C to 1V at 100°C and any voltage measurement circuit connected across the output pins can read the temperature directly. The input and ground pins of this heat-to-voltage converter IC are connected across the regulated power supply rails and decoupled by R1 and C1. Its temperature-tracking output is applied to the non-inverting input (pin 3) of the comparator built around IC2. The inverting input (pin 2) of IC2 is connected across the positive supply rails via a voltage divider network formed by potentiometer VR1. Sinc...

How often does it happen that you close down Windows and then forget to turn off the computer? This circuit does that automatically. After Windows is shut down there is a ‘click’ a second later and the PC is disconnected from the mains. Surprisingly enough, this switch fits in some older computer cases. If the circuit doesn’t fit then it will have to be housed in a separate enclosure. That is why a supply voltage of 5 V was selected. This voltage can be obtained from a USB port when the circuit has to be on the outside of the PC case. It is best to solder the mains wires straight onto the switch and to insulate them with heat shrink sleeving. C8 is charged via D1. This is how the power supply voltage for IC1 is obtained. A square wave oscillator is built around IC1a, R1 and C9, which drives inverters IC1c to f. The frequency is about 50 kHz. The four inverters in parallel power the voltage multiplier, which has a multiplication of 3, and is built from C1 to C3 and D2 to D5. This is use...

In any recording situation, monitoring is critical to make sure you're getting what you want on tape. This is just as true in field recording, but in most cases, one's monitoring options are severely limited--stereo headphone is the only choice. Headphone Monitoring Switch  : Since I often use dual-mono mics, hearing a stereo feed of the two is not always convenient. I wanted the option to hear JUST the left mic in BOTH ears, or just the right mic in both ears, as well as a normal stereo signal. This is simple enough to do with a big rotary switch. When completed, you can create a little box that your headphones plug into, which in turn is plugged into the stereo phone output of your deck. Then, by turning the knob on the switch box, you can hear normal stereo, left-only mono, right-only mono, left+right mono and even left-right reversed stereo (or normal stereo again).  Note the use of summing resistors in the left+right mono section. This was an attempt to prevent the two ...