HOME     STORE     BLOG     SCHEMATICS     TUTORIALS     DOWNLOADS     CONTACT
  Electronic Schematics
FM Transmitters
PLL Synthesizers
Stereo Encoders and Decoders
Antennas
FM Receivers
Audio / Amplifiers
Power Supplies
AC/DC Inverters AC/DC Converters
Battery Chargers
Remote Control
PC Related
Test and Measurement
PIC / ATMEL / AVR
USB Circuits
Telephone Related
LED
Miscellaneous Circuits
Stepper Motors
 Schematics  >> 

Page 3 of 3:  1  2 3

Telephone Listening Bug
Here is a simple transmitter that when connected to a phone line, will transmit anything on that line (execpt the dial tone) to any FM radio. The frequency can be tuned from 88 to about 94Mhz and the range is about 200 feet. It is extremely easy to build and is therefore a good, useful beginner project.


Telephone Receiver
An interesting circuit and handy electronic telephone receiver, suited for receiving incoming calls, is described here. This circuit can be connected to almost all types of telephone exchange lines. To simplify the gadget, the dialer section has been omitted. The circuit can be constructed on a medium size veroboard.


Telephone Recorder
This nifty little circuit lets you record your phone conversations automatically. The device connects to the phone line, your tape recorder's microphone input, and the recorder's remote control jack. It senses the voltage in the phone line and begins recording when the line drops to 5 volts or less. R1 1 270K 1/4 W Resistor R2 1.5K 1/4 W Resistor R3 68K 1/4 W Resistor R4 33K 1/4 W Resistor C1 0.22uF 150 Volt Capacitor Q1, Q2 2N4954 NPN Transistor D1 1N645 Diode MISC Wire, Plugs To Match Jacks On Recorder, Board, Phone Plug.


Telephone Recorder Switch
This circuit will allow you to record both sides of your telephone conversations for future reference. For commercial orders placed over the phone such a recording device is invaluable.


Telephone Remote Switch
This device connects to the telephone line and can be used to remotely control up to 4 relay outputs using a DTMF (tone dialing) telephone. A number of user settings are available to improve the useability and security of the device. The kit comes complete with a small plastic case with silk-screened front and rear panels.


Telephone Ringer by IC KA2411
Simple telephone Ringer with KA2411 IC.


Telephone Voice Changer
Although this kind of voice effect can be obtained by means of some audio computer programs, a few correspondents required a stand-alone device, featuring microphone input and line or loudspeaker outputs. This design fulfills these requirements by means of a variable gain microphone preamplifier built around IC1A, a variable steep Wien-bridge pass-band filter centered at about 1KHz provided by IC1B and an audio amplifier chip (IC2) driving the loudspeaker.


Watch-Dog for Telephones
Most of the telephone security devices available in market are simple but quite expensive. These devices provide blinking or beeping type line-tap/misuse indications. Quite often they do not offer guaranteed protection against unauthor-ised operation. A very simple and uni- que circuit of a telephone watch-dog to safeguard subscriber telephone lines against any fraud is described here. This little circuit keeps continuous watch over the telephone lines and sounds an alarm in case of any misuse. In addition it transmits a loud tone through the telephone lines to prevent further misuse.


Page 3 of 3:  1  2 3


Accurate LC Meter Capacitance Inductance Meter with 16F628 and LCD
Volt Ampere Meter with 16F876 Microcontroller and LCD display
 
Accurate LC Meter

Build your own Accurate LC Meter (Capacitance Inductance Meter) and start making your own coils and inductors. This LC Meter allows to measure incredibly small inductances making it perfect tool for making all types of RF coils and inductors. LC Meter can measure inductances starting from 10nH - 1000nH, 1uH - 1000uH, 1mH - 100mH and capacitances from 0.1pF up to 900nF. The circuit includes an auto ranging as well as reset switch and produces very accurate and stable readings.
PIC Volt Ampere Meter

Volt Ampere Meter measures voltage of 0-70V or 0-500V with 100mV resolution and current consumption 0-10A or more with 10mA resolution. The meter is a perfect addition to any power supply, battery chargers and other electronic projects where voltage and current must be monitored. The meter uses PIC16F876A microcontroller with 16x2 backlighted LCD.

50MHz 60MHz Frequency Meter / Counter with 16F628 & LCD
1Hz - 2MHz XR2206 Function Generator
60MHz Frequency Meter / Counter

Frequency Meter / Counter measures frequency from 10Hz to 60MHz with 10Hz resolution. It is a very useful bench test equipment for testing and finding out the frequency of various devices with unknown frequency such as oscillators, radio receivers, transmitters, function generators, crystals, etc.
1Hz - 2MHz XR2206 Function Generator

1Hz - 2MHz XR2206 Function Generator produces high quality sine, square and triangle waveforms of high-stability and accuracy. The output waveforms can be both amplitude and frequency modulated. Output of 1Hz - 2MHz XR2206 Function Generator can be connected directly to 60MHz Counter for setting precise frequency output.

BA1404 HI-FI Stereo FM Transmitter
USB IO Board PIC18F2455 / PIC18F2550
BA1404 HI-FI Stereo FM Transmitter

Be "On Air" with your own radio station! BA1404 HI-FI Stereo FM Transmitter broadcasts high quality stereo signal in 88MHz - 108MHz FM band. It can be connected to any type of stereo audio source such as iPod, Computer, Laptop, CD Player, Walkman, Television, Satellite Receiver, Tape Deck or other stereo system to transmit stereo sound with excellent clarity throughout your home, office, yard or camp ground.
USB IO Board

USB IO Board is a tiny spectacular little development board / parallel port replacement featuring PIC18F2455/PIC18F2550 microcontroller. USB IO Board is compatible with Windows / Mac OSX / Linux computers. When attached to Windows IO board will show up as RS232 COM port. You can control 16 individual microcontroller I/O pins by sending simple serial commands. USB IO Board is self-powered by USB port and can provide up to 500mA for electronic projects. USB IO Board is breadboard compatible.

ESR Meter / Transistor Tester Kit
Audiophile Headphone Amplifier Kit
 
ESR Meter / Capacitance / Inductance / Transistor Tester Kit

ESR Meter kit is an amazing multimeter that measures ESR values, capacitance (100pF - 20,000uF), inductance, resistance (0.1 Ohm - 20 MOhm), tests many different types of transistors such as NPN, PNP, FETs, MOSFETs, Thyristors, SCRs, Triacs and many types of diodes. It also analyzes transistor's characteristics such as voltage and gain. It is an irreplaceable tool for troubleshooting and repairing electronic equipment by determining performance and health of electrolytic capacitors. Unlike other ESR Meters that only measure ESR value this one measures capacitor's ESR value as well as its capacitance all at the same time.
Audiophile Headphone Amplifier Kit

Audiophile headphone amplifier kit includes high quality audio grade components such as Burr Brown OPA2134 opamp, ALPS volume control potentiometer, Ti TLE2426 rail splitter, Ultra-Low ESR 220uF/25V Panasonic FM filtering capacitors, High quality WIMA input and decoupling capacitors and Vishay Dale resistors. 8-DIP machined IC socket allows to swap OPA2134 with many other dual opamp chips such as OPA2132, OPA2227, OPA2228, dual OPA132, OPA627, etc. Headphone amplifier is small enough to fit in Altoids tin box, and thanks to low power consumption may be supplied from a single 9V battery.
 

Arduino Prototype Kit
RF Remote Control 433MHz Four Channel
 
Arduino Prototype Kit

Arduino Prototype is a spectacular development board fully compatible with Arduino Pro. It's breadboard compatible so it can be plugged into a breadboard for quick prototyping, and it has VCC & GND power pins available on both sides of PCB. It's small, power efficient, yet customizable through onboard 2 x 7 perfboard that can be used for connecting various sensors and connectors. Arduino Prototype uses all standard through-hole components for easy construction, two of which are hidden underneath IC socket. Board features 28-PIN DIP IC socket, user replaceable ATmega328 microcontroller flashed with Arduino bootloader, 16MHz crystal resonator and a reset switch. It has 14 digital input/output pins (0-13) of which 6 can be used as PWM outputs and 6 analog inputs (A0-A5). Arduino sketches are uploaded through any USB-Serial adapter connected to 6-PIN ICSP female header. Board is supplied by 2-5V voltage and may be powered by a battery such as Lithium Ion cell, two AA cells, external power supply or USB power adapter.
200m 4-Channel 433MHz Wireless RF Remote Control

Having the ability to control various appliances inside or outside of your house wirelessly is a huge convenience, and can make your life much easier and fun. RF remote control provides long range of up to 200m / 650ft and can find many uses for controlling different devices, and it works even through the walls. You can control lights, fans, AC system, computer, printer, amplifier, robots, garage door, security systems, motor-driven curtains, motorized window blinds, door locks, sprinklers, motorized projection screens and anything else you can think of.
 
  Latest Schematics
FM Transmitter with Booster
TDA7000 FM Radio Receiver with LM386 Amplifier
BA1404 Stereo FM Transmitter with Booster
Portable Variable Bench Power Supply 1-32V 0-5A
1 Watt FM Transmitter Booster
Arduino DCC Decoder
Simplest FM Receiver
7W FM Transmitter
Simple Stereo FM Transmitter using an AVR Microcontroller
Stereo FM Receiver
Simple DIY FM Transmitter
50W Power Amplifier with LM3886
BLF147 150W VHF Amplifier
Fully Adjustable Power Supply
Stereo FM Transmitter with BA1404 IC
High Performance Stereo Audio Amplifier using LM3886
1Km FM Transmitter with UA741 Opamp
Easy Crystal Locked FM Transmitter
Adjustable Delay Circuit
DIY Adjustable Bench Power Supply
BA1404 FM Stereo Transmitter with Amplifier
LM350 3A Adjustable Voltage Regulator
1 Watt FM Amplifier
TDA2050 Stereo Audio Power Amplifier
DIY Walkie Talkie
5km FM Transmitter
Bench Lab Power Supply 0-50V 0-5A
Tiny FM Transmitter
3V One Transistor FM Transmitter
FM Music Transmitter

Electronics-DIY.com © 2002-2024. All Rights Reserved.