Switching Circuits
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Linear Technologys LT®3466 is a dual step-up converter capable of driving up to 20 white LEDs with a programmable constant current. The device is also capable of driving asymmetric LED strings with independent dimming and shutdown control for multipanel.... -
The circuit in Figure 1 is a keypad interface that solves this problem by using an ultralow-power microcontroller. The circuit typically consumes 100 nA while awaiting a key press and consumes a maximum of only 2 µA if all keys are stuck or held down. An....
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This circuit is used to trigger a camera`s electronic shutter circuit when a flash of lightning is present. This circuit would also work for photographing fireworks displays or other events involving flashes of light... -
As systems grow smaller, it becomes increasingly attractive to replace mechanical potentiometers with electronic potentiometers, which are smaller and less expensive silicon equivalents. A common interface for such devices comprises a Chip-Select, Increment....
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The dual-channel PCA9540 I2C multiplexer often breaks up an I2C or SM bus or allows you to use devices with the same addresses on the same bus. When the PCA9540 initially powers up, it comes up in a state in which both channels are deselected. The I2C- or....
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The circuit lowers this dissipation after actuation by applying less than the normal 5V operating voltage. Note that the voltage required to turn a relay on the pickup voltage is greater than the pickup voltage required to keep in on the dropout voltage. The....
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Typical circuit representative of those used in most light switch type digital timers. The timer module is normally a PIC or custom chip, and it syncs to the AC line so that a trigger pulse can be supplied at the right moment... -
In an effort to conserve energy, simple shutdown schemes are incorporated into many battery-operated circuits. Not all circuits lend themselves to direct control, however, and instead the supply must be turned off by a switch. The LTC®1477 high side....
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Most portable systems have built-in PCMCIA sockets as the sole means of expansion. The requirements of the PCMCIA specification have led to some confusion among system designers. This Design Note will attempt to lessen the confusion and highlight other....
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The circuit of the mains current detector is shown in Figure 1. By using a few cheap diodes, a resistor, LED and LDR, a simple opto-isolated detector can be created. This entire circuit dissipates very low power, and can safely be housed in a heatshrink.... -
You can easily improve on a previous Design Idea to produce a slightly simpler resistor arrangement with better timing balance between switches, using a single resistor value (Reference 1, Figure 1). The use of a single resistor value, RS, in a series chain....
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Circuits that latch one-of-N switches usually use a digital approach. Such circuits are often useful in human-interface situations, such as audio-mixing consoles, video-feed selection, or current-loop-control redundancy systems. In high-precision analog....
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Digitally controlled potentiometers are useful for generating analog control voltages under the control of a microcontroller. In some applications, manual pushbutton switches could replace a microcontroller and simplify product design. Mechanical switches....
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At times, a µC must read a large number of DIP switches, such as for system identification, bus-address setup, manual configuration, or other purposes. However, the available number of I/O lines is sometimes not enough to assign a switch to each one. You can....
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Some machines need to run for long periods and therefore may finish their work in the middle of the night or during the weekend. For the time remaining, until the operator returns, the machines stay idle, uselessly consuming power. This Design Idea allows a....
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Designers of microcontroller-based products that require a keypad for user data entry can select from dedicating an input line for each key, continuously polling the keypad`s x and y lines, or generating an interrupt whenever a user presses a key. Although....
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Many power-supply designers like to have a regulator latch off in the event of an overcurrent situation or other fault condition. Yet, many PWM controllers do not internally support this latch-off function. Most do, however, have a power-good output and an....
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When the "ON/OFF" button is pressed once, the equipment goes on and stays on. It goes off when the button is pressed again. The circuit is straight forward. It uses a JK CMOS FlipFlop to with its JK terminals tied high to achieve the toggling action. The.... -
The delay time for all circuits shown has been revised. The optimum is around 100ms - sufficient for around 5 full cycles at 50Hz, or 6 cycles at 60Hz. It is also quite alright to run the transformer to around 200-500% of full load current at start-up, and.... -
This circuit will remove the transient spikes and contact bounces from a non-latching push button switch. Using a 555 timer as a monostable circuit, it is easy to build a good switch debouncer circuit. There are many circuits for SPDT debouncing, but not.... -
This sensitive sound operated switch can be used with a dynamic microphone insert as above, or be used with an electret (ECM) microphone. If an ECM is used then R1 (shown dotted) will need to be included. A suitable value would be between 2.2k and 10kohms... -
You may be familiar with this effect. You switch audio equipment such as an amplifier to a different input and there is a loud click or "thump" in the speaker system. Not all equipment is affected. Some high end audio systems never suffer, but intercoms.... -
This circuit is very basic to build. To open a lock which is connected to the K1 Load, you must press each momentary switch in the correct sequence. The sequence used in this circuit is S1, S2, S3 and finally S4. If any of the other switches are pressed the.... -
The MPF102 (Q1) can be replaced with a NTE451 or ECG451, but still widely available. JFET-N-CHAN, UHF/VHF AMP. The 2N3565 (Q1/Q2) can be replace with a 2N2222(A), BC107, BC108, BC109(A/B/C), NTE123A, or ECG123A. The TIP31 (Q3) can be replaced with a NTE196.... -
Dual Channel Relay Board is a simple and convenient way to interface 2 relays for switching application in your project. Input - 12 VDC @ 84 mA. Output - two SPDT relay. Relay specification - 5 A @ 230 VAC. Trigger level - 2 ~ 5 VDC. Berg pins for connecting.... -
This project describes how to build a "soft touch" switch. By "soft touch" we mean that you have to push once to set device ON and push again to set device OFF. This kind of switch works by latching a relay to ON state with push of a button and with another.... -
Just the solution for AVR applications in which I/O is tight, such as the ATtiny12. This should work well on other kids of controllers that have independently controlled I/O direction registers, such as PIC and 6805 controllers. This is a solution was.... -
With a DPDT switch, I can switch the two data lines. I tried connecting the shields from the two computers together, the grounds two computers together, switching the D+ and D- lines with the DPDT switch, and leaving the VBus lines float, but for some reason.... -
This is a simple circuit that does the day/night switchings you have in mind. POT1 is used to set the light level at which the circuit switches from enable to disable... -
The traditional potentiometer is implemented with an electrical contact that slides over a resistive layer. An example of a well-known audio-grade potmeter is the Alps Blue. I still use this one myself. A high-end (good and costly) alternative is the rotary.... -
This board layout was created using the SOIC version of a PIC16F627A without drawing the usual schematic first. Most of the part values are etched on the Layout. The SIP resistor packs I used are 10k ohm, some experimentation with this value may be.... -
The main box of the Transmit Selector system is designed to be located in the technical rack of a small radio broadcast station. There are four stereo balanced line inputs, either of which can be routed to a stereo balanced output. The signal routing is....
New Circuits
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is.... -
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to.... -
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This.... -
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the.... -
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,.... -
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the.... -
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power.... -
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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