Electronics Infoline Web

4 MHz amplitude modulated RF source

http://72.41.86.92/dproj/LPAM/4mmo.htm

4-20 mA Digital to Process Current Transmitter

Describes a three IC, 4-20 mA process current, digital-to-analog converter

http://www.analog.com/UploadedFiles/Application_Notes/266329066AN21.pdf

4.5-10Mhz Superheterodyne receiver

http://www.web-ee.com/Schematics/Superhet/superhet.htm

40 kHz light receiver is immune to ambient light

you can achieve a range of several hundred feet with a standard TV or VCR remote control module.

http://www.imagineeringezine.com/PDF-FILES/40krvr1.pdf

40 kHz TV-VCR light source repeater

designed to be placed directly in front of a standard TV or VCR remote to amplify the IR pulses to 10 timers stronger to operate a TV or VCR over three times the normal distance.

http://www.imagineeringezine.com/PDF-FILES/40kvcr.pdf

40 MHz Wideband RF Amplifier

No tuned elements. Does not use in resonant circuits

http://users.otenet.gr/~athsam/RF_amp_wide_band.htm

40+ MHz 5-digit frequency counter

with an AVR 2313

http://www.myplace.nu/avr/countermeasures/index.htm

40khz IR Tester

http://www.reconnsworld.com/ir_ultrasonic_40khzirtest.html

40KHz Laser Burst Detector

generates a 100mS output pulse whenever it detects a 3ms to 5ms laser burst modulated at 40KHz. It is very sensitive and could be modified for long range laser communications.

http://www.imagineeringezine.com/PDF-FILES/40krvr3.pdf

40KHz Modulated Light Detector

uses a unique cascode amplifier circuit to convert the current from a PIN photo diode to a current without any feedback network. Conversion factor of 10 volts per microwatt at 900nm.

http://www.imagineeringezine.com/PDF-FILES/40krvr2.pdf