Vacuum Tubes Valves
Musical & effects
Yagi Uda Antennas
Metal Detector Circuits
Liquid Sensing Circuits
Light Sensing Circuits
Voltage Detector Circuits
Air-Gas Detection Circuits
Human Sensing Circuits
RF & Radiation
Optical Sensing Circuits
Free Energy Circuits
AC to DC & DC to DC
Solar Cell Circuits
Micro Power Circuits
Switching Power Supplies
Light Laser LED
Digital to Analog
Analog to Digital
Data Bus Circuits
Voltage to Pulse
Current to Voltage
Frequency to Voltage
RF Converter Circuits
Sine to Square Wave
Voltage to Current
voltage to frequency
Period to Voltage
Video Wall circuits
TV Video Circuits
Motor Control Circuits
8051 / 8052
PCB CAD Software
Car bike Circuits
555 Timer Circuits
Remote Control Toy
H Bridge Circuit
Interconnection & Timing
Digital Signal Integrity
Digital & Bipolars
Sensors & Detectors
Regulated Power Supply
4 Band Resistor
5 Band resistor
6 Band resistor
Light Laser LED Circuits
One transistor LED Flasher
This may be the simplest LED flasher circuit you can build, with the notable exclusion of LED's with integrated flashing circuits. This might be a good replacement for the LM3909 in some applications. Take a close look. Only the emitter and collector leads of the 2N2222 are connected. The base lead was cut off. The LED is from a string of...
AVR LED RF Field Strength
Useful as a transmitter tune-up meter or an RF sniffer, this is an RF field strength indicator that is loosely based on the Broad Band RF Field Strength Probe, described elsewhere. It detects RF via a square law detector, basically its a crystal set with gain. The bias circuit for the detector is significantly modified from the probe to reduce...
Precision LED Blinker
The circuit allows a precision regulated drive current to be set to drive an LED, and in response to a TTL level signal, the LED is switched on and off with rise and fall times of less than 500 nanoseconds and less than 7% overshoot. This was designed for biological experiments to study the photo repsonse of cone cells rabbit eyes. This circuit...
Christmas LED lights circuit with 555 timer
This circuit sequence through a pattern of Christmas lights to turn on and off each string of lights, one at a time. After sequencing through all strings, the circuit turns the last string off, then turns all strings on, and then off, before repeating the pattern. Some simple wiring changes will let you set up other patterns. This circuit...
LED effects with ATTYNI2313
This project I made for my little daughter. It is 24 channel light illumination. The schematic is very simple ? 24 LED?s, 1 MCU and some additional components. The main principle is dynamic indication, which is usually implemented for control of 7-segment digital indicators. Here is the same, as for indicators are used traditional 5-mm LED?s.For...
1A Low Noise High Current LED Torch/Flash
An ultralow dropout current source maintains accurate LED current at very low ILED voltages. Automatic mode switching optimizes efficiency by monitoring the voltage across the LED current source and switching modes only when ILED dropout is detected. The LTC3216 is available in a small 3mm x 4mm 12-Lead DFN package. The LTC®3216 is a low noise,...
100mA Ultralow Noise LED Supply with Current Adjust
The LTC3201 contains overtemperature protection and can survive an indefinite output short to GND. Low external parts count (one small flying capacitor and three small bypass capacitors) and small MSOP-10 package size make the LTC3201 ideally suited for space constrained applications. An input noise filter further reduces input noise,thus...
LED flashing with 3909 IC circuit
This project uses a 3909 IC and a few other parts; power is 1.5 volts DC.
White LED Step-Up Converters with Schottky
The LT®3465/LT3465A are step-up DC/DC converters designed to drive up to six LEDs in series from a Li-Ion cell. Series connection of the LEDs provides identical LED currents and eliminates the need for ballast resistors. These devices integrate the Schottky diode required externally on competing devices. Additional features include output...
Low Cost Alternative to LEDs for Backlighting
The circuit shown in Figure 1 is specifically designed to control a single 1W CCFL. T1, Q1, Q2 and associated components form a current fed resonant Royer converter that produces a high voltage at transformer T1s secondary winding. The CCFL current is the feedback signal to the LTC®1697. The LTC1697 delivers switch mode power to the...
ALPHANUMERIC LED DISPLAY PROJECT
A tiny sandwich flag connected perpendicular to the motor spindle aids observation of how long it takes to complete one full rotation. This worked initially, as each burst from the capacitor barely moved the flag 1/4 of a rotation. As the circuit variations became more efficient and powerful (the capacitors values became larger), a single burst...
Buffer amplifier and LED improve PWM power
Figure 2 shows another approach that requires additional components but delivers the full magnitude of the voltage ramp to Pin 3 of IC1 and provides the approximately 1V-dc offset that Reference 1 requires. Transistors Q1 and Q2, resistors R1 and R2, and LED D3 form an emitter-follower amplifier for the ramp voltage available at IC1, Pin 7...
Buck IC boosts battery voltage for white LED
Figure 1 presents an alternative to the typical boost power regulator. A buck-converter IC, IC1, generates the higher voltage that the white-light LED needs. An internal buck power stage connects between VIN and PGND, sourcing current to output Pin L. This circuit operates by turning on the high switch, thereby connecting the battery voltage...
LED Indicates Two Power States
The circuit in Fig. 1 uses a single bicolor LED to indicate both power-on and blown-fuse conditions. Regardless of the condition of the fuse, the green side of the LED is always on for each positive half-cycle of the ac input. With a 120Vrms ac input the average diode current is a little more than 10mA. If the fuse is good, current cannot...
1.5 Volt LED Flasher Circuits
The LED flasher circuits below operate on a single 1.5 volt battery. The circuit on the upper right uses the popular LM3909 LED flasher IC and requires only a timing capacitor and LED. The top left circuit, designed by Andre De-Guerin illustrates using a 100uF capacitor to double the battery voltage to obtain 3 volts for the LED. Two sections of...
LED characteristics with PSpice
To model an LED in PSpice, use the diode model. You can set the IFK and ISR parameters in the diode model to zero; Figure 1 shows the resultant PSpice diode forward-current model and corresponding equations. As the equations in the figure show, you can express the forward voltage across the diode model, or VFWD, as the sum of the voltage across...
Powering White LEDs in Series or Parallel Connections
White LEDs are popular for portable equipment LCD backlights because they are less complex, less expensive, and smaller than CCFL backlights. Portable equipment like PDAs, cellphones, and digital cameras require backlights because they are converting to color LCD displays. This article discusses charge-pump and inductor step-up converter...
32 Bi-Colour LEDs Christmas Tree
Next is the microcontroller or MCU. In previous projects, we used the Atmel AT89C2051. However, the I/O port structure is not quite suitable for this application so we have used the similar Atmel AT90S2313. The main feature influencing this decision is that the 2313 outputs can be "turned off" while the 2051 outputs always have pullups enabled....
dimming control for white-LED driver
Figure 1 shows the classic way to use a backlight-driver IC to provide dimming. By modulating an external PWM signal, the circuit controls the white-LED current. By adjusting the on/off-time ratio, or duty cycle, the circuit can provide drive ranging anywhere from full-on to full-off. This circuit relies on the fact that the baseband or...
Circuit drives and quantities LEDs
The circuit mixes LEDs of different forward-bias requirements, yet keeps the loads reasonably well-balanced through use of a current mirror comprising transistors Q1 through Q4. It also eliminates the need for a separate current-limiting "ballast" resistor on each LED or string of LEDs and provides a common control point (IC1`s ADJ pin) for...
Circuit switches bipolar LED
The circuit in Figure 1 represents one method to switch a bipolar, two-color LED using an SPDT mechanical switch or relay. This circuit wastes power and does not work properly if the power-supply voltage is not substantially more than the sum of the LEDs` forward voltages. The circuit is, therefore, marginal, to the point of being unusable, with...
Circuit Regulates White-LED Bias Current
The compact circuit (Figure 1) overcomes these problems. The regulated buck/boost charge pump in a small µMAX package (U1) has a 100mA output-current capability. Configured as shown, the circuit directly regulates bias current flowing through the white LED. By biasing multiple white LEDs in parallel, it can provide good light distribution. The...
LED Stroboscope with EG1951-ND
The rotary switch is available for $5.00USD as of 2003 from DigiKey under part number EG1951-ND or EG1952-ND. It is a real pain to operate this circuit without a proper switch. You can put multiple 4017 ring counters in series to reduce the duty cycle in order to obtain a more focussed strobe image but you will have to increase LED current to...
Constant converter drives white LEDs
Figure 1 shows the LT1618 driving a 1W, white Lumileds (www.lumileds.com) LXHL-BW02 Luxeon LED. You need no external op amps for this compact approach. The LXHL-BW02 has a forward voltage of 3.1 to 3.5V for 250 mA of current. Although the maximum dc rating of the LED is 350 mA, you can pulse it up to 500 mA for a camera flash. R4 is set for...
DC/DC LED Driver in ThinSOT
The LT®1932 is a fixed frequency step-up DC/DC converter designed to operate as a constant-current source. Because it directly regulates output current, the LT1932 is ideal for driving light emitting diodes (LEDs) whose light intensity is proportional to the current passing through them, not the voltage across their terminals. With an input...
secondary colors from multicolored LEDs
Figure 1 shows the various LED-circuit configurations, and Figure 2 shows the timing to generate all three colors from bicolor and tricolor LEDs, although using only one LED`s operating current. Note that the driver for the bicolor LED must be able to sink and source current. You may have to provide color balance between the primary-color LEDs...
10 Dancing LEDs
The basic circuit illuminates up to ten LEDs in sequence, following the rhythm of music or speech picked-up by a small microphone. The expanded version can drive up to ten strips, formed by up to five LEDs each, at 9V supply. IC1A amplifies about 100 times the audio signal picked-up by the microphone and drives IC1B acting as peak-voltage...
DC/DC Converter Drives Lumileds White LEDs
Powered from two alkaline cells, the circuit in Figure 2 can illuminate a 1W LXHL-BW02 LumiledsTM white LED with a constant 320mA current at 85% efficiency. The forward voltage of the 1W LED, 3.6V typical, requires a boosted voltage from the 2-cell input. In order to turn off the LED, an input disconnect switch is required. Typically in...
Driver thermally compensates LED
The circuit in Figure 1 allows you to compensate for both of these temperature-dependent problems, using only the TSF-102 sensor from Texas Instruments (www.ti.com). The device is a temperature-dependent positive-temperature-coefficient resistor with a linear temperature coefficient of approximately 0.7%/°C at 25°C. For the circuit in Figure 1,...
Control Brightness and Power Efficiently of LEDs
This application note describes how LEDs (including white LEDs) work. The note also explains how to drive them in battery-powered LED applications, including lithium-ion (Li+ or Li-ion), nickel-cadmium (NiCd), and nickel metal-hydride (NiMH) rechargeable handheld devices where power consumption is important. LED brightness-matching and the value...
Dual White LED Step-Up Converter & Schottky
LT3466 is a dual full function step-up DC/DC converter specifically designed to drive up to 20 White LEDs (10 in series per converter) with a constant current. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminating the need for ballast resistors and expensive factory calibration. The LT3466...
LED driver delivers constant luminosity
The circuit in Figure 1 is similar in principle to that of a previous Design Idea (Reference 1) but offers improved, more reproducible performance. The output current is almost constant over an input-voltage range of 1.2 to 1.5V and is insensitive to variations of transistor gain. Transistors Q1 and Q2 form an astable flip-flop. R1 and C define...
Light Sensing Circuits
Light Dimmer Circuits
Ultrasonic distance finder circuit
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 measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
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 find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
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 circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
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 circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
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, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
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 calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
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 supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
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. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
Digital Signal Integrity
Interconnection and Timing of Digital Circuits
CMOS Circuits Tutorial