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
DIY HV Variable Cap
DIY PMA alternator
Interconnection & Timing
Digital Signal Integrity
Digital & Bipolars
Sensors & Detectors
Regulated Power Supply
4 Band Resistor
5 Band resistor
6 Band resistor
This circuit will run from a single 5 V power supply. The LTC1043 switched-capacitor instrumentation building block provides a differential-to-single-ended transition using a flying-capacitor technique. Cl alternately samples the differential input signal and charges ground referred C2 with this information. The LTC1052 measures the voltage...
The circuit uses the LTC1043 in a variable gain amplifier which features continuously variable gain, gain stability of 20 ppm/Â°C, and single-ended or differential inputs. The circuit uses two separate LTC1043s. LTC1043B is continuously clocked by a 1-kHz source, which could also be processor supplied. Both LTC1043s function as the sampled...
The DG419looks into the high input impedance of the op amp, so the effects of Rvs(o"l are negligible. The DG441 is also connected in series with RIN and is not included in the feedback dividers, thus contributing negligible
Increased Feedback-Stabilized Amplifier
The usual method for using a current-feedback amplifier to drive a capacitive load isolates the loa
Protected Intrinsically Safe Op Amp Circuit
The circuit is designed to drive an external load. A fault condition in the external load circuit could feed excessive current or voltage back into the line drive circuit. If excessive voltage appears from the load, the two zener diodes will clamp that voltage to a safe level, which in this case is 10 V.The current in the zener diodes, op amp,...
Low Noise And Drift Composite Amp Circuit
This circuit offers the best of both worlds. It can be combined with a low input offset voltage and drift without degrading the overall system`s dynamic performance. Compared to a standalone FET input operational amplifier, the composite amplifier circuit exhibits a 20-fold improvement in voltage offset and drift. In this circuit arrangement,...
ZKJ-S-type buffer controller circuit
As ZKJ-S-type buffer controller circuit for motor starting slip control. Buffer controller by the two operational amplifier Ai and Az composition. Ai constitute a speed amplifier saturated, Az constitute an
Parametric MID Frequence EQ
The circuit constitutes a natural extension of Mic-Line balance unit, but can be adapted to any other audio circuit. It is made up of two units in the series : A) A classic unit bass/ Treble and B) a parametric unit of mid frequencies. Both units can also be used autonomously or each one separately, with the required buffer unit, from previous...
Modular Class A Buffer preamplifier
A unit which is often very useful, if we need to isolate, in sound circuits, two stage between them. Then we can use this circuit which has an amplified unit, which gain X1, we do not use total negative feedback, only local, with the result that distortion remains at a very low level. Matching must be done with great care to the types of...
5 band graphic equalizer using a single IC/chip
This circuit uses a single chip, IC BA3812L for realizing a 5 band graphic equalizer for use in hi-fi audio systems.The BA3812L is a five-point graphic equalizer that has all the required functions integrated onto one IC. The IC is comprised of the five tone control circuits and input and output buffer amplifiers. The BA3812L features low...
Low Voltage Preamplifier
This is a special low voltage version of my audio preamp. T1`s emitter voltage is biased close to half supply voltage (1.5V) to allow for maximum output voltage swing. Both transistors are direct coupled and have closed loop feedback to aid temperature stability. T2 realizes the amplifiers full voltage gain, and for low noise operation, T2...
CCD Array Reader Project
The CCD Array Reader project began with a free sample of the Texas Instruments TC102-1 CCD Linear Image Sensor and its rather terse data sheet. The TC102-1 provides virtually no support circuitry, only the raw CCD (with a few special pixels) and a simple output buffer. The board shown below was designed to continously scan the TC102-1 and output...
18-MHz oscillator with automatic level control
A recent Design Idea described a method for designing simple, high-frequency LC oscillators with few passive components (Reference 1). However, for best results, practical hardware design of a stable oscillator requires more parts and greater complexity. Figure 1 shows a stable, 18-MHz oscillator with automatically leveled output amplitude...
Inexpensive peak detector requires few components
Requiring no rectifier diodes, the positive peak-detector circuits in figures 1 and 2 exploit the open-drain output of a Texas Instruments TLC372 fast comparator, IC1. Both versions of the detector are simple and inexpensive and provide a buffered, low-impedance output at VOUT. In addition, the TLC372`s high typical input impedance of 1012...
An 89C2051 CPU 8 driver outputs
This document describes the HSETI PCB. This PCB is a small simple application for the Atmel AT89C2051 microprocessor - a 20 pin 8051 variant, with FLASH (reprogrammable) program memory. The board has just two chips on it, the CPU and a driver/buffer.
Feedback circuit eliminates CCD-driver delay mismatch
In a CCD (charge-coupled device), packets of charges shift across the array. The transistor array, also called a bucket-brigade shift register, receives drive from a dual-phase clock signal. Dual-phase clock signals comprise two synchronized clock signals that are 180° out of phase. High peak-output-current CCD drivers can buffer the logic-level...
Serial Cable for Casio Digital Cameras
I built this cable for my Casio QV-200 digital camera, it should work for many Casio models. It`s basically a inverting buffer/converter to/from RS-232 voltage levels from/to CMOS levels. Why Casio didn`t put this inside the camera like everyone else does is beyond me. I built the circuit inside the hood of the DB9F connector.
Simple FIFO provides data-width conversion
Many designs require FIFO elastic buffers to form a bridge between subsystems with different clock rates and access requirements. However, in some applications, you need FIFO buffers for data conversion. One example is the case in which you need to connect an 8-bit ADC to a 16-bit data-bus microprocessor through a FIFO buffer (Figure 1).
Deglitching Techniques for High-Voltage R-2R DACs
In an R-2R DAC design with supply voltages exceeding ±5V, large voltage glitches (up to 1.5V) can occur during the DAC`s major-carry transitions. These glitches can propagate through the output buffer amplifier and appear at output. The slewing of the level shifters that control the top (VREF+) and bottom (VREF-) single-pole double-throw...
Differential amp drives high-speed ADC
The schematic in Figure 1 is the discrete-element version of an A/D-converter drive circuit. The circuit converts a single-ended input to a differential output. The ADC`s reference voltage determines the common-mode range of the differential outputs. The circuit contains two AD9631 amplifiersone connected in noninverting mode, and the other...
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...
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 or Lamp Pulser
This circuit operates a LED in pulsing mode, i.e. the LED goes from off state, lights up gradually, then dims gradually, etc. This operation mode is obtained by a triangular wave generator formed by two op-amps contained in a very cheap 8 pin DIL case IC. Q1 ensures current buffering, in order to obtain a better load drive. R4 & C1 are the...
NE555 Basic Monostable
Here the popular 555 timing IC, is wired as a monostable. The timing period is precise and equivalent to:- 1.1 x R1 x C1 With component values shown this works out at approximately 1.1msec.The output duration is independant of the input trigger pulse, and the output from the 555 is buffered and can directly interface to CMOS or TTL IC`s,...
PC monitors two-way RS-232 transmission
The method in Figure 1a needs no access or knowledge of the communicating devices. A C program opens two COM ports and installs interrupt-service routines for IRQ4 and IRQ3. Upon the reception of an interrupt, the routine stores a byte in a common circular buffer with the COM identifier and error flags. The main program displays the contents of...
The Link telephone intercom is designed around two ICs. The first, IC1, is an NE 556 dual timer chip, which is wired up to provide dial tone, ring tone (busy tone too, which will be explained along with a few add-ons to be mentioned later on) and ring pulses for the ringer circuit attached to each line circuit. The other chip, IC 2, is a CD...
Guitar Reverb Pedal project
This circuit was inspired by a friend who wanted a reberb for his portable guitar amplifier. I originally tried using NE5532 low noise op-amps for the buffer stages but they were too noisy for the low level circuits so I switched to discrete 2N3904 transistors, they seem to be fairly quiet. This circuit has a nice feature not found in...
Serial MIDI Interface
This page describes how to build this full-bandwidth single-port (one input and one output) MIDI interface. The interface is buffered (that is, if the PC gets behind you won`t lose data) and it works in Windows 3.1 and Windows 95 using a special (and very well-behaved) device driver. A simpler version, using an Atmel AT89C2051 microprocessor, is...
LED Audio Power Indicator
This circuit is intended to indicate the power output level of any audio amplifier. It is simple, portable, and displays three power levels that can be set to any desired value. IC1A is the input buffer, feeding 3 voltage comparators and LEDs drivers by means of a variable dc voltage obtained by R5 and C4 smoothing action. The simplest way to...
Inverters form three-phase VCO
The inspiration for the VCO in Figure 1 came from Texas Instruments application notes of years ago, detailing the use of unbuffered U-type inverters for use in ring oscillators. The application notes circuit consists of only the inverters. The circuit generates relatively squarish waveforms. Any ring oscillators operation depends on the...
Audio Tone Control
Based on the classic Baxendall tone control circuit, this provides a maximum cut and boost of around 10dB at 10K and 50Hz. The first BC109C transistor (left hand side) is acting as a buffer. It provides the circuit with a high input impedance, around 250k has a voltage gain of slightly less than unity.
Tunable IF with TDA7000
This circuit has `suffered` a lot of modifications over its long life... Even the lettering on the integrated circuit was partially erased of the years. The main motive of the mods was not that the circuit didn`t work right, but were several tries to add some kind of frequency indicator to the receiver. The left RCA plug and associated...
555 Timer Circuits
RC Model Toy Circuits
H Bridge 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...
DIY HV Variable Capacitor
DIY PMA Alternator Plans
Digital Signal Integrity