Other Circuits
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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 design was developed by request of a correspondent having made a sort of LED candle and needing to switch off the LED with a puff. This simple, easy to build gadget can be useful as a prop for Halloween and Christmas season, shows and the like... -
This circuit was designed to provide that continuous light lamps already wired into a circuit, become flashing. Simply insert the circuit between existing lamp and negative supply. Especially suited for car or panel pilot lights, this device can drive lamps.... -
Upon opening your fridge door the photocell is exposed to light and the piggy oinks. Reverse engineered circuit diagram is of an early commercial design which uses an OP-AMP to make simulated pig sounds. Modern Fridge Pigs sound much better because they.... -
This box is a set of nine relaxation oscillators. It blinks random patterns and looks cool. When the voltage on the capacitors charge to 65 volts, the neon gas ionizes and discharges the capacitors to 55 volts. The frequency can be simply calculated from the.... -
This simple CPO is for those who want to practice Morse Code in a different way, ie with out the morse key. It can be also used as a touch operated door bell. The popular timer IC555 is wired as astable multivibrator. The frequency (tone) can be changed by.... -
Morse Tutor is a program written in C++. It can be used for learning or sending morse code. Morse code uses long (dash) and short (dot) sounds to communicate. The dot is the basic unit and the dash is equal to the length of three dot's. Morse Code was.... -
This is not a sophisticated automatic keyer but it is lot QRP to build and to have fun operating it. When the paddle is connected to the DOT terminal, C1 starts to charge. When C1's charge reaches sufficiently high value, it causes the transistor BC157B.... -
IR appliances use pulses (control signals) sent over a modulated IR carrier wave. The carrier wave may be modulated at various frequencies, 36-38KHz being the most popular.Some Satellite receivers use even higher frequencies than this. The IR1 remote module.... -
The device described here does just that. The circuit connects to the doorbell circuit - taking power from the 18 VAC from the doorbell transformer and switching power to the doorbell circuit most of the day. The user interface is a pushbutton, a toggle.... -
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.... -
The uWatch comes as a kit of parts. All of the electronic SMD parts on the PCB are pre-assembled. The uWatch is normally in sleep mode and powers down the LCD to save battery power. (approx 3mA LCD on, and 15uA LCD off) To switch the uWatch on press either.... -
This was designed to flash a pair of LEDs to be mounted on the wing tips of a Parkzone Citabria R/C (remote control) airplane. The unmodified Parkzone Citabria only weights 20 grams (about 0.7 oz), so weight, and therefore the number and size of the.... -
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.... -
The 555 timer IC is connected for Astable Operation, the clock pulses are fed to the 4017 IC via the 10K resistor. The 4017 is a 10 stage counter, each of the outputs is connected to the appropriate LED, as some LEDs need to be on for more than one count, we.... -
Two examples of the most common types of Voltage followers (buffers). You can find some theory behind them in our amplifier gain and buffer amplifier pages.his first circuit is a very simple one transistor voltage follower. Consist of two biasing resistors,.... -
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.... -
The object of Quick Draw is to test your reaction time against your opponent's. A third person acts as a referee and begins the duel by pressing S1, which lights LED1. Upon seeing LED1 go on, you try to outdraw your opponent by moving S2 from "Holster".... -
The purpose of this circuit is to automatically turn off any device plugged into its power outlets after a certain period of time. Shutoff is activated by an absences of an audio signal or by a standard timer function. This unit would be connected to speaker.... -
The ISD1000A is a Direct Analog Storage device which allows you to store 20 seconds worth of voice data on an IC chip which can be play backed anytime. The data stored will stay in memory even if the power is removed. To use the circuit below simple apply.... -
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.... -
These items were sold nationally several years ago. The fish would sing, open its mouth, turn its head, and flap its tail. After removing the back panel, all of the existing electronics were removed leaving only the 3 servo motors, speaker and photocell. The.... -
This device 'listens' to a conversations and then interjects words and phrases at inappropriate times. I got this box at a local thrift store for $1.50 (special, this week only). It has a nice hinged top and a place to insert a panel with a designed glued.... -
This circuit is a small digital ?roulette''. It is constituted by oscillator IC1, the counter IC2, the transistors Q1-7 that drive the display common cathode DSP1. The supply basically becomes from a battery 9V, but can become also from one power supply..... -
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.... -
The IC1 is a 555 timer IC is connected for, Astable operation the clock pulses are fed to the IC2 via the 10K resistor. The IC2 is a 10 stage counter, output 6 (pin 5) is connected to RESET (pin 15), thus giving us a 6 stage counter , outputs 0 to 5. The 6.... -
The particular circuit is substantially a generator of accidental numbers, from 1 until the 6. The clue him we see in a line from led, that each one corresponds also in a number from the 1-6, if push and leave, the S1 (push button). This movement corresponds.... -
This circuit us gives the sense of movement of ball up down, after the LED turn on successively the one afterwards the other. As soon as it reaches in the one or in the other end it makes again the opposite movement to behind. As clock are used two inverters.... -
This circuit is a double direction flash. Similar to Digital Ping- Pong 1, there is a movement of a lit dot, up and down along the LED's length. When the D16 lit the situation changes and there is a reverse movement. Lit D15-14 ??D16, is lit making circles....
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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