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Amplifier Circuits:  Intermediate Frequency (IF)
Amplifier -- Main Page

IF Circuits:  #'s - H     I - Z

Last Updated: December 25, 2017 01:43 PM

Circuits Designed by Dave Johnson, P.E. :

175Khz Inductive Pulse Receiver   -  This circuit is discussed in more detail in the Experimenters Journal.  The receiverís six inch diameter coil detects the ring signal from the above transmitter and use a single NPN transistor to provided enough amplification for the signal to be easily viewed on an oscilloscope . . . Circuit by Dave Johnson P.E.-July 09, 2006

1Khz to Over 70Mhz Light Receiver   -  This circuit uses one tiny C-MOS inverter IC to form a modulated light receiver with a very fast response.  It is designed around a PIN photo diode that is packaged for use with plastic optical fibers.  It can be used as an optical fiber receiver.  By using the open end of the optical fiber it can "sniff" out any modulated light signals . . . Hobby Circuit designed by David Johnson P.E.-June 11, 2000

1us LED Pulse Driver + Voltage to Frequency Converter   -  This circuit receives the signal from the above amplifier and launches powerful 1uS infrared light pulses from a low cost LED that are frequency modulated by the audio information.  The 10KHz center frequency of the pulse stream is low enough so a standard . . . Hobby Circuit designed by David A. Johnson P.E.-March 22, 1999

2Mhz Broad Band Optical Fiber Receiver   -  if you need more sensitivity than the above circuit this circuit provides about ten times more gain.  It too is designed around an inexpensive plastic optical fiber detector . . . Hobby Circuit designed by David A. Johnson P.E.-June 09, 2000

2uS Light Pulse Receiver   -  Although the LF357 is an obsolete part, this circuit gives you an idea how to build a sensitive modulated light detector with high ambient light immunity.  The first section uses a 100mH inductor as an efficient photodiode current to voltage conversion circuit . . . Circuit by David A. Johnson P.E.-June 03, 2002

30Khz Light Receiver Amp   -  This circuit uses NPN darlington transistor to amplify the signal produced from short light flashes, as detected by a PIN photo diode.  The circuit draws only about 330uA from a 6v battery . . . Circuit by Dave Johnson P.E.-March 07, 2002

40Khz Light Receiver Amp   -  This circuit is similar to 30KHZ LIGHT RECEIVER AMP  but provides more gain and operates up to 40KHz.  However it draws more power supply current.   . . . Circuit by David Johnson P.E.-March 07, 2002

40Khz Ultrasound Receiver   -  A X100 transistor amplifier is followed by a zero cross detector circuit, using a voltage comparator.  The output is a TTL logic signal, corresponding to the received 40KHz signal . . . Circuit by David Johnson P.E.-January 29, 2006

5Mhz Broad Band  Optical Fiber Receiver   -  This circuit is a simple broad band light detector that uses a very inexpensive IC and a PIN photodiode that is packaged for use with plastic optical fibers.  It has a bandwidth from 1KHz to over 5MHz.  It is great for experimenting with various modulated . . . Circuit by David A. Johnson P.E.-June 04, 2000

AIR Transparency Monitor, Xenon Flash Receiver   -  I designed this receiver circuit many years ago to monitor the quality of a mile long column of air for future optical communications experiments.  The transmitter system (circuit 72 below) uses a powerful xenon flash in conjunction with a large 12 inch . . . Circuit by David A. Johnson P.E.-June 17, 2000

AIR Transparency Monitor-Pg2   -  This is Page 2 of the receiver circuit AiR TRANSPARENCY MONiTOR, XENON FLASH RECEiVER . . . Circuit by Dave Johnson P.E.-June 17, 2000

Broad Band 2Mhz Optical Fiber Receiver   -  if you need more sensitivity than the above circuit this circuit provides about ten times more gain.  It too is designed around an inexpensive plastic optical fiber detector . . . Circuit by Dave Johnson P.E.-June 09, 2000

High-speed 75MHz light receiver   -  This circuit uses one tiny C-MOS inverter IC to form a modulated light receiver with a very fast response.  It is designed around a PIN photo diode that is packaged for use with plastic optical fibers.  It can be used as an optical fiber receiver.  By using the open end of the optical fiber it can "sniff" out any modulated light signals . . . Circuit by David Johnson P.E.-June 11, 2000


Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

100Khz Low Power Light Receiver -  By starving a high speed logic inverter for current, this circuit can produce a sensitive 100KHz light receiver circuit, which is immune to ambient light, but only drawing 100 microamps from a 3 volt supply . . . Hobby Circuit designed by Dave Johnson P.E.-April, 2005

10Mhz to 20Mhz Light Receiver -  Light power to volts conversion = APPROX.15mV per microwatt at 850nM. . . Circuit by David Johnson P.E.-July, 2006

175Khz Inductive Pulse Receiver -  This circuit is discussed in more detail in the Experimenters Journal.  The receiverís six inch diameter coil detects the ring signal from the above transmitter and use a single NPN transistor to provided enough amplification for the signal to be easily viewed on an oscilloscope. . . Circuit by Dave Johnson P.E.-June, 2000

1Khz to Over 70Mhz Light Receiver -  This circuit uses one tiny C-MOS inverter IC to form a modulated light receiver with a very fast response.  It is designed around a PIN photo diode that is packaged for use with plastic optical fibers.  It can be used as an optical fiber receiver.  By using the open end of the optical fiber it can "sniff" out any modulated light signals . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

1us LED Pulse Driver + Voltage to Frequency Converter -  This circuit receives the signal from the above amplifier and launches powerful 1uS infrared light pulses from a low cost LED that are frequency modulated by the audio information.  The 10KHz center frequency of the pulse stream is low enough so a standard . . . Hobby Circuit designed by David A. Johnson P.E.-March, 1999

2Mhz Broad Band Optical Fiber Receiver -  If you need more sensitivity than the above circuit this circuit provides about ten times more gain.  It too is designed around an inexpensive plastic optical fiber detector . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000

2uS Light Pulse Receiver -  Although the LF357 is an obsolete part, this circuit gives you an idea how to build a sensitive modulated light detector with high ambient light immunity.  The first section uses a 100mH inductor as an efficient photodiode current to voltage conversion circuit. . . Circuit by David A. Johnson P.E.-June, 2002

30Khz Light Receiver Amp -  This circuit uses NPN darlington transistor to amplify the signal produced from short light flashes, as detected by a PIN photo diode.  The circuit draws only about 330uA from a 6v battery. . . Circuit by Dave Johnson P.E.-March, 2002

40Khz Light Receiver Amp -  This circuit is similar to 30KHZ LIGHT RECEIVER AMP  but provides more gain and operates up to 40KHz.  However it draws more power supply current.. . . Circuit by David Johnson P.E.-March, 2002

40Khz Ultrasound Receiver -  A X100 transistor amplifier is followed by a zero cross detector circuit, using a voltage comparator.  The output is a TTL logic signal, corresponding to the received 40KHz signal. . . Circuit by David Johnson P.E.-January, 2006

5Mhz Broad Band  Optical Fiber Receiver -  This circuit is a simple broad band light detector that uses a very inexpensive IC and a PIN photodiode that is packaged for use with plastic optical fibers.  It has a bandwidth from 1KHz to over 5MHz.  It is great for experimenting with various modulated. . . Circuit by David A. Johnson P.E.-June, 2000

AGC Amplifier features 60-dB dynamic range -  4-Aug-05 EDN-Design Ideas Using discrete components only, build an audio-band AGC __ Circuit Design by Julius Foit, Department of Microelectronics, CTU Prague, Czech Republic

AGC disciplines RF & fiber signals so they "ain't misbehavin'" -  EDN-Design Ideas -- 02/02/1998   AGC disciplines RF and fiber signals so they "ain't misbehavin'"BILL SCHWEBER, TECHNICAL EDITORYou may need AGC to keep wayward RF, optical, and video signals--which swing over a wide dynamic range--within acceptable bounds.  By considering key specifications and techniques, you can get optimum AGC results. __ Circuit Design by Bill Schweber, Technical Editor, EDN

AGC Uses an Analog Multiplier -  11/03/11  EDN-Design Ideas -   (Originally published in the September 4, 1986, EDN-Design Ideas)  In the AGC circuit of Fig 1, a 4-quadrant analog multiplier   (IC1), an amplifier stage   (IC2), an active, full-wave rectifier   (D1, D2, R4-R7, and IC3), and an integrator   (IC4) accomplish automatic gain control of VINís amplitude variations in the audio-frequency range. __ Circuit Design by Steve Lubs, Department of Defense, Washington, DC

AIR Transparency Monitor, Xenon Flash Receiver -  I designed this receiver circuit many years ago to monitor the quality of a mile long column of air for future optical communications experiments.  The transmitter system   (circuit 72 below) uses a powerful xenon flash in conjunction with a large 12 inch. . . Circuit by David A. Johnson P.E.-June, 2000

AIR Transparency Monitor-Pg2 -  This is of the receiver circuit AIR TRANSPARENCY MONITOR, XENON FLASH RECEIVER. . . Circuit by Dave Johnson P.E.-June, 2000

An IQ Demodulator-Based IF-to-Baseband Receiver with IF & Baseband Variable Gain & Programmable Baseband Filtering  -  This circuit is a flexible, frequency agile IF-to-baseband receiver. Variable gain at both IF and baseband is used to adjust the signal level. The ADRF6510 baseband ADC driver also includes a programmable low-pass filter that eliminates out-of-channel blockers and noise. __ Analog Devices from the Lab

An IQ Demodulator-Based IF-to-Baseband Receiver with IF & Baseband Variable Gain & Programmable Baseband Filtering  -  This circuit is a flexible, frequency agile, direct conversion IF-to-baseband receiver. A fixed conversion gain of 5 dB reduces the cascaded noise figure. Variable baseband gain is used to adjust the signal level. The baseband ADC driver also includes a programmable low-pass filter that eliminates out-of-channel blockers and noise. __ Analog Devices from the Lab

Broad Band 2Mhz Optical Fiber Receiver -  If you need more sensitivity than the above circuit this circuit provides about ten times more gain.  It too is designed around an inexpensive plastic optical fiber detector. . . Circuit by Dave Johnson P.E.-June, 2000

Constant-Impedance IF bandpass filters improve performance -  Application Note __ MiniCircuits.com

Crystal switcher using diodes -  Schematic only, no circuit description __ Designed by Guy Roels ON6MU

Direct Crystal radio receiver examples -  Ham RadioV-U)HF AMPLIFIERSchematic __ Designed by Guy Roels ON6MU

High-speed 75MHz light receiver -  This circuit uses one tiny C-MOS inverter IC to form a modulated light receiver with a very fast response.  It is designed around a PIN photo diode that is packaged for use with plastic optical fibers.  It can be used as an optical fiber receiver.  By using the open end of the optical fiber it can "sniff" out any modulated light signals. . . Circuit by David Johnson P.E.-June, 2000

I.F. Amplifier -  The I.F.  transformer primary has 18 turns, the secondary winding has 4 turns.  The capacitors across the IFT primaries are 82pF.  The input/output transformer has 12 turns, tapped at 3 turns from ground.  This transformer is wound on a ferrite core.  The MOSFETs are 3SK45's.  The diodes in the product detector are 1N34's.  I use a six pole SSB filter from a scrap CB.  The centre frequency is 7.8MHz.  The -6db bandwidth is about 2.5KHz. __ Designed by EI9GQ homebrew radio

IF Amplifier -  Three of these amplifiers are used in series to build the 455 kHz IF amplifier.  AGC voltage comes from the AGC Circuit.  The diagram above shows the circuit for the second IF amplifier. __ Designed by Web David White, WN5Y


 Intermediate Frequency (IF):  #'s - H     I - Z


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