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
ON/OFF button using Microcontrollers
Using a switch to power up your microcontroller projects may not be a good idea if you need to "wake" the PIC during some events. For example: A metal detector sends a pulse indicating a car is ready to enter into a garaje, so the user needs to type a password to open the garage door or just slide the access card. You may leave the...
Video Switcher with PIC16F819
This device uses the second method (which, if you don't already know, requires about 100 times less parts), but adds motion detection to switch cameras. The usual way to detect motion is to store a complete video frame and then look for changes on successive frames. Again, a lot of trouble can be saved by only sampling 64 locations on the...
Analog Switch for Oscilloscope
The analog switch multiplexes between channel 1 and channel 2 at the end of each sweep. Controls include Dual Trace/Single Trace mode, sync polarity, sync level, and sync on + or - (rise or falling) edges.
Atari joystick to PC joystick adapter
ome games are easier to play with digital joystick instead of analogue type. Unfortunately PC has only analogue joystick connector, which makes it impossible to connect normal digital joystick to it. But with a little adapter circuit, it is possible to use Atari style digital joystick with IBM PC joystick interface. The circuit adapts the...
8 way Up/Down Switcher
As with the Electronic sel. 8 we also have here a circuit with a choice of 8 different sources. The difference is that only two of the switches are used and the movement of commands is Up-Down in series. We have evidence of activity at each entrance by the corresponding Led 1-8. Throw the SL1 connector, we drive the Relay of the circuit Relay...
Mains Delay Switch For Lambs and Motors
A circuit that will find enough applications. Basically the designing became in order to exist delay in quench one or more lamps in a stairwell or in any other space exists this need. It can become use, for the control various motor or other appliances, what is connected in the contacts of J3. The activation command is given by exterior pressing...
Timer switch circuit
A 100 second delayed turn ON relay RL1 switch, if plug power +12V in circuit. In Fig.2 see a two range 6-60 second and 1-10 minute auto turn off relay timer circuit, with 555.
Electronic Switch ON-OFF
Here we have three choices, with which we can make electronic switches that use our touch or pressing (push button). We thus exploit the very big resistance of entry, that present the gates CMOS. In the fig.1 we have two gates NAND or NOR (IC1), connected as R-S flip-flop. Just as we press the switch S1, the exit 3 it becomes [H], even it is...
Light Detector circuit
This circuit give low level output, when exist enough lighting, that is a detector of light. It can give, say ,command turn on somebodies lights, when fall the dark. His exit is compatible with TTL level and it give low logic level, when phototransistor Q1, detect light. With adjustable resistor RV1, we can regulate the sensitivity that it will...
under?-over voltage detector
In Fig.1 A precision DC under?voltage relay switch. The opamp is wind as a voltage comparator, with a reference voltage applied to pin 2 and the test voltage applied to pin 3: the relay turns on when the pin 3 voltage exceeds that of pin 2. The circuit can be made to trip at any voltage in excess of 5 volts by suitable choice of R1 value. In...
Touch Switch with 555
The modern mechanic switches are improved concerning of old technology. We need however many times to replacement some old switch or to check currents bigger than the durability of certain switches or simple we need something with modern appearance. For he and different reasons is essential the up circuit. He is simple in the manufacture and...
Touch Switch with relay
A simple circuit with which we have the possibility opening and closing the RL1 contacts. He becomes touching a small metal surface. Clue of situation that is found RL1, is become by the Led D3. The supply of circuit is +12V, the IC1 is supplied with 3.9V fall of voltage that is ensured by combination R5 and zener D2. For more good restoration...
Touch Light Dimmer circuit
With this circuit we can change the brightness of lamb, with a only key of touch. The key of touch is connected in the circuit, center of which is a special completed IC1, which is the S566B of SIEMENS. This IC, it processes the information of duration of touch and then it checks the brilliance of lamb, according to this information. If we touch...
Signal and Tone Activated Relay Switch
In the Fig.1, exist a circuit, which is a sensitive switch that corresponds in AC signals of input, for signals above 5mV. Corresponds in all the signals from 50 HZ until 3KHZ, region in which found the human voice. The RV1 is regulated so much what RL1 it?s in situation OFF, when the input is it has null signal. In the Fig.2, exist a band -...
Temperature limit Relay
This circuit, is basically a resistance ? sensing window switch, except that the ?resistor? takes the form of an NTC thermistor and the circuit thus responds to temperature. TH1 must have a resistance in the range 500ohm - 9Kohm. RV1 is used to set half ? supply volts on the RV1 ? TH1 junction at the ?mean? temperature.
8 input Relays circuit
It is the essential continuity of circuits Sel 8 Sources and Up/Down Sel 8 Sources, but can work and autonomously, collaborating with any suitable circuit of control. The Relay 1-8 can be 6-24v DC. For current of collector of transistors Q1-8, bigger the 10 mA, it is better we use BD 139 or BD 679 with R 1-8 is 15K?.
8 way electronic selector / switch
The Elect. Sel. 8 is a simple circuit, with a choice of 8 sources of any sort ,of 8 independent switches. Each switch corresponding with a relay for example the switch S1 activates the RL1 e.t.c. The uses of the circuit are quite a few, choice of entrances in a sound amplifier, choice of command, in a digital circuit etc. In each entrance a...
Electronic 10 way Selector Relays
This is a circuit for alternative sources selection. It combines mechanical selection using a rotating switch S1, the electronic drive of the relays RL 1-10 and also the optical indication of the selection by the Display DSP1. The function is based on the connection of the mechanical selections into 4 Bit (BCD) code. It is managed by the proper...
Voltage window switch
A voltage window switch is in practice the basic lower window limit of this circuit is roughly 3V and the upper limit is 9V. The window range can be extended by fitting a suitable range
RS-232 Data Switch
This report deals with the design for a small asynchronous serial data switch. The switch architecture allows 14 serial ports supporting a subset of the RS-232 protocol. The requirements for the switch are discussed. The hardware interfaces are described in detail, and the software function is described in the form of a user's manual. Finally,...
Temperature Control switch
This circuit controls a load (in this case a dc brushless fan) based on a temperature compared with a setpoint. THe transduced is a diode in the forward polarization regime. In fact when forward biased, the forward voltage drop accross a diode has a temperature dependance, in particular has a negative linear(ish) slope. This because of the...
Video Camera switcher MAX454
The video switcher described here can display the output of two, three, or four cameras on a single monitor. The number of cameras is set by a DIP switch on the circuit board. That feature avoids blank displays if less than four cameras are used by sequencing through only the inputs that are connected to a camera. In the automatic mode, the...
Light/dark relay switch
This kit is the most basic, practical circuit to build using an LDR to turn on a relay. The two transistors connected as a Darlington pair give the circuit enough sensitivity, while the trimpot give sensitivity adjustment. The switching point of the relay is dependent on the supply voltage and temperature. This circuit is satisfactory if...
Touch detecting Switches
One of the unusual features of the out-of-production Programmable Drum Set was its use of touch switches for control. Like most touch switches, these detect the difference in the capacitance of a plate when it is being touched by a finger versus the parasitic capacitance of the plate alone. The capacitance added by touching the plate is detected...
USB selector switch
To share a regional press like the USB printer, scanner etc. two computers, it is relatively easy. Just connect the two computers on a network device and say the printer as shared. This method however requires the continued operation of the computer we plugged the printer. Solution to above problem is to give the circuit that we present, and has...
Touch Switch illuminates LED
Our circuit is amplifying the current flowing through your finger (when it touches the touch plate) 10,000 times and this is sufficient to illuminate the LED. The current flowing through your finger (when touching the touch plate) is only a few microamps and this is not enough to illuminated the Light Emitting Diode (LED). We need an amplifier...
Sound Controlled Switch
Described here is a very inexpensive solution to many phono-controlled applications like remote switching on, for instance, or activating a camera, tape recorder, burglar alarms, toys, etc. The circuit given here employs a condenser microphone as the pick-up. A two-stage amplifier built around a quad op-amp IC LM324 offers a good gain to enable...
Advanced LED Flasher with 555
This circuit uses three easily available 555 timer ICs. All three work as astable multivibrators. The first 555 has an on period and off period equal to 1 sec. This IC controls the on/ off periods of the other 2 555s which are used to flash two bulbs through the relay contacts. The flashing occurs at a rate of 4 flashes per second. The diodes...
Auto ON-OFF lights
An ordinary automatic room power control circuit has only one light sensor. So when a person enters the room it gets one pulse and the lights come on. When the person goes out it gets another pulse and the lights go off. But what happens when two persons enter the room, one after the other? It gets two pulses and the lights remain in off state....
Optical toggle switch with 4027
Using dual flip-flop IC CD4027 employ a 555 based monostable circuit to supply input clock pulses. The circuit described here obviates this requirement. One of the two flip-flops within IC CD4027 itself acts as square wave shaper.
Sound activated switch circuit
An infra-red or wireless remote control has the disadvantage that the small, handy, remote transmitter is often misplaced. The sound operated switch has the advantage that the transmitter is always with you. This project offers a way to control up to four latching switches with two claps of your hand. These switches may be used to control lights...
Ultrasonic switch circuit
This circuit functions with inaudible (ultrasonic) sound. Sound of frequency up to 20 kHz is audible to human beings. The sound of frequency above 20 kHz is called ultrasonic sound. The circuit described generates (transmits) ultrasonic sound of frequency between 40 and 50 kHz. As with any other remote control system this cirucit too comprises a...
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...
Digital Signal Integrity
Interconnection and Timing of Digital Circuits
CMOS Circuits Tutorial