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
Digital Switching System
This circuit can control any one out of 16 devices with the help of two push-to-on switches. An up/down counter acts as a master-controller for the system. A visual indication in the form of LEDs is also available. IC1 (74LS193) is a presettable up/down counter. IC2 and IC3 (74LS154) (1 of 16 decoder/demultiplexer) perform different functions,...
Digital Volume Control
This digital volume control has no pot to wear out and introduces almost no noise in the circuit. Instead, the volume is controlled by pressing UP and DOWN buttons. This simple circuit would be a great touch to any home audio project. Using a dual polariity power supply (+-5V works fine) will cure most clipping problems. You will have to check...
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.
CD-ROM Drive as Digital-audio CD-Player
ACD-ROM drive can be used as a stand-alone unit for playing digi- tal audio CDs without interfacing with a computer. The stereo output of CD player available at the audio jack can be amplified using audio input facility which is normally available on a tape deck/tape recorder or a stereo amplifier. Audio socket on front/rear of the CD-ROM drive...
Circuit forms industrial-grade digital potentiometer
Both ac and dc motors in modern industrial systems often receive their control from PLCs (programmable-logic controllers) in a control room safely away from the process. If an operator must manually set the motor speed while observing the process, the component of choice is usually an industrial-grade potentiometer. The wiper of this...
Current-limit switch is digitally programmable
Current-limit switches are virtually ubiquitous in system controls. They provide a safe means for regulating the current delivered to a load circuit. The switches allow the load current to increase to a programmed limit but no higher. Typically, the current limit is a function of the voltage across an external resistor, produced by the current...
Digital Call Sign Annunciator
One of the requirements that is easily overlooked is the need to identify your station during your video communications. From what I have seen, some R/C wireless video users are neglecting to broadcast their ham radio call sign. Essentially, USA hams must do so every ten minutes and at the end of their communication. Here is a excerpt from the...
Digital current source is nonvolatile
Digitally programmable current sources that feature automatic trimming and retain the setting despite power-down cycles are useful in applications such as RF- and laser-communications drivers. The circuit in Figure 1, for example, is particularly suited for setting the drive current for the optical pump in widely tunable VCSELs (vertical-cavity...
Digital Data Signal Crosstalk on the Clock
Crosstalk from digital data signals into the clock signal of a data-conversion system can cause hard-to-diagnose problems. This obscure problem is different than the crosstalk from digital data signals into the analog signal path, which was the subject of Part 1. There is value to understanding this different crosstalk problem at a deeper level,...
Digital Mains Voltage Indicator
Continuous monitoring of the mains voltage is required in many ap- plications such as manual voltage stabilisers and motor pumps. An analogue voltmeter, though cheap, has many disadvantages as it has moving parts and is sensitive to vibrations. The solidstate voltmeter circuit described here indicates the mains voltage with a resolution that is...
Digital Step-Km Counter
Hardware is located in a small box slipped in pants` pocket and the display is conceived in the following manner: the leftmost display D2 (the most significant digit) shows 0 to 9 Km. and its dot is always on to separate Km. from hm. The rightmost display D1 (the least significant digit) shows hundreds meters and its dot illuminates after every...
Digital Step-Km Counter
This circuit measures the distance covered during a walk. Hardware is located in a small box slipped in pants` pocket and the display is conceived in the following manner: the leftmost display D2 (the most significant digit) shows 0 to 9 Km. and its dot is always on to separate Km. from hm. The rightmost display D1 (the least significant digit)...
Effects of Digital Crosstalk in Data Converters
What is the effect of digital signal bits cross-talking into the analog section of a data-conversion system? There is a lot written into the data sheets of ADCs and DACs on how to minimize it. But, when asked what is the result, most laymen have the insight that "it creates noise". While this is a very true statement, there is value to...
EPROM Programmer Mk2
This design was never completely finished, so consider it to be in the very early experimental stage. I don`t sell kits, programmed PLD`s, or provide support for this project, and I will never be published. But if you want to take a bash at making it yourself, be my guest, it may or may not work, I guarantee nothing. Try it at your own risk.
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).
Finite State Machine Programmable Logic Controller
I have had this project hanging around for ages and have tried to submit it for publication without much enthusiasm so I will make everything available here for the individual constructor. The complete Pascal source code for the compiler program is available below.
A Hierarchical Priority Encoder
Anormal priority encoder encodes only the highest-order data line. But in many situations, not only the highest but the second-highest priority information is also needed. The circuit presented here encodes both the highest-priority information as well as the second-highest priority information of an 8-line incoming data. The circuit uses the...
Interfacing Sony control stick to Empeg
You may find that there are too few, if your power is very noisy (as can happen in a car environment) it may help to place a 0.1uF and/or 10uF capacitor before and/or after the voltage regulator. At the moment I`m not using these but at this point I`ve only tested it on the bench, not in the car. I`ll update this web page after it`s all installed.
508A microcontroller can deliver a maximum of 25mA
A typical device that requires less than 5v and draws less than 25mA is an LED. A LED must be supplied with an exact voltage for it to operate correctly. Because it requires LESS than 5v, a dropper resistor (current limiting resistor) must be included in series to "take-up" or "absorb" or "interface" the LED to the output line. Working out the...
Replacement For The LM3909 LED Flasher / Oscillator
This page features a replacement circuit for the LM3909 LED Flasher / Oscillator using discrete components. The circuit is functionally the same as the integrated LM3909 but has a minor variation of the components used. Naturally the circuit will not be as physically as compact as the integrated circuit but it does offer the ability to adjust...
Logic offers complementary-switch control
The circuit in Figure 1 provides not only a complementary drive signal but also a deadtime delay on both rising and falling edges. The high-speed inverter gates use IC1, a 74HC04 CMOS circuit, and 1N5819 Schottky diodes D1 and D2. The 74HC04 inverter features symmetrical input thresholds, VIHMIN and VILMAX, at 70 and 30% of the supply voltage,...
Logic PSU with Overvoltage Protection
The 5 volt regulated power supply for TTL and 74LS series integrated circuits, has to be very precise and tolerant of voltage transients. These IC`s are easily damaged by short voltage spikes. A fuse will blow when its current rating is exceeded, but requires several hundred milliseconds to respond. This circuit will react in a few microseconds,...
Make a DAC with a microcontroller`s PWM timer
Many embedded-microcontroller applications require generation of analog signals. An integrated or stand-alone DAC fills the role. However, you can often use PWM signals for generating the required analog signals. You can use PWM signals to create both dc and ac analog signals. This Design Idea shows how to use a PWM timer to simultaneously...
Digital Storage Oscilloscope Adapter
A digital storage oscilloscope (DSO) is a very important piece of test equipment that can do the jobs that a normal CRO just can`t handle. Such as capturing single shot and widely spaced waveshapes, and looking at non repetitive signals that can`t be triggered on a CRO.
The logic designer is filled with features. It would not be possible to list all the possible combinations of the unit as the various building blocks on the board can be interconnected to obtain a wide variety of counting and testing stages. You will be able to see what we mean after you build the project and start to interconnect the blocks...
This LOGIC PULSER capable of delivering pulses of various compositions, to any type of circuit you wish to test. Basically it is designed to complement the LOGIC PROBE and can be used in situations where the LOGIC PROBE is not so effective. It is an improvement over a multimeter in that it has an audible output and is NOT triggered when...
PIC to RS232 Interface
The circuit shown will convert logic level voltages to and from RS232 serial voltages levels. For basic serial comms between a Microchip PIC and a PC or other device you generally only need to connect the Gnd, Txd and Rxd lines. This little circuit will work with a supply voltage of 3.3v to 5v making it ideal for interfacing with a PIC
Voltage programmable square wave generator
Here's another daft yet interesting PIC12F675 idea I came up with. When I wanted to show someone how logic gates worked I could only find a NAND gate which wasn't very handy for demonstrating AND's OR's, NOR's and ExOR's. I also wanted to have a play with the A/D converter on the 12F675 so I came up with the idea of a PIC that could function as...
Logic Probe with 74LS47
This circuit is a Logic Probe. It indicates the logic state of the node of any TTL logic circuit. To do that, we have to supply the probe with the same power of the circuit that we want to analyse: same Vcc and same GND. To check the logic level, we must connect the "Test" wire of the probe to the desired node of the circuit that we want to...
Logic Probe with PIC12F683
This project is based on a probe logic states, capable of measuring levels from TTL (5v) to state levels of PLC's (24v). For this we have employed the use of the PIC 12F683 microcontroller, which by its nature is capable of operating at low voltages, in this case 3vcc, besides having analog inputs and internal oscillator. The circuit is...
Simplified logic checker. Logic voltage levels have the ability to display LED (Of course I (^_^;)." H "in the LED is green," L "and red LED lights, and so both the open and goes out . But not only that was put on the ability to detect narrow pulses. In doing Shottomaruchibaibureta be extended to a short, pulse, this pulse of about 100ns in LED...
Auto poweroff for power supplies circuit
Probably the easiest way of doing automatic switch off is with relay logic. In the diagram, the box marked RL1 is the coil, the 2 in the coil box tells you there are two sets of contacts somewhere on the circuit, operated by this coil. In this simple circuit, it's easy to see them!Sw1 is a momentary push switch. When it's pushed (contacts...
Digital to Analog Circuits
Analog to Digital Circuits
Data Logging Circuits
Data Bus 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