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Signal Adder Circuits

 

Last Updated: October 09, 2017 03:39 PM


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

1-Transistor Amplifier/Detector -  An amplifier may be added to boost the audio level as shown below.  The current consumption of this amplifier is quite low and a power switch is not included.  Disconnect the battery when the receiver is stored for long periods.   __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

2-transistor Radio -  Here is a simple radio that was designed to minimize unusual parts; there isn't even a detector diode!  The sensitivity isn't as high as the one-transistor reflex but the simplicity is attractive.  Strong stations will provide plenty of volume __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

BPF and Mixer -  SSB Transceiver-Receiver Section:  The signal from the RX/TX relay is filtered by an 80Mtr band pass filter.  This can be replaced by a filter for another band or a bank of switched filters, for a multI band rig.  if you need to cover from 3.5 to 4.0 MHz, you will need to replace the 10p coupling capacitor with one of a larger value (about 18p).  You can wind your own inductors, about 18 turns on a 10K type Toko former will have 5.5 microhenries of inductance. __ Designed by EI9GQ homebrew radio

Broadband 6 GHz Active Mixer with a Glueless Local Oscillator Interface  -  Equipment Needed, Bullet text, CiRCUiT EVALUATiON AND TEST, The control software was used to program the desired LO frequency and the output power.  Figure 9 is a sample screen shot of the software configuration used to drive the ADF4351.  See UG-435 User Guide, Evaluation Board for the ADF4351 Fractional-N PLL Frequency Synthesizer and UG-476 User Guide, PLL Software installation Guide for further information on setting up the ADF4351__ Analog Devices from the Lab

CMOS RF PLL Sythesizer -  Synthesizer based on available CD4059.  CD4046 and CD4060 IC s.   __ Designed by Harry Lythall-SM0VPO

Crystal Radio -  The crystal radio gets its name from the galena crystal (lead sulfide) used to rectify the signals.  A "cat's whisker" wire contact was moved about the surface of the crystal until a diode junction was formed.  The 1N34A germanium diode.   __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Crystal Radio RF Amplifier -  One of the best places to add a transistor to a simple crystal radio is at the front end in the form of an RF amplifier.  The circuit below is a simple but effective amplifier which will give surprising performance improvement.  This amplifier __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Crystal Radio Set Version 2 -  This uses a more standard ceramic / crystal earpiece and LT44 transformer that you can buy easily.  Look out though, this is a draft version.   __ Designed by Henry 

Experiments with Detector Diodes -  When building crystal radios or other simple receivers, the experimenter often wonders about the relative performance of the different diodes in the junk box.  Here are the results of several experiments using the typical.   __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

High input IP3 mixer enables robust VHF receivers -  08/29/14 EDN Design Ideas:  LTC Design Notes 515: An increasing number of applications occupy the 30MHz to 300MHz very high frequency (VHF) band.  Television and radio broadcasting, navigation controls and amateur radios are a few examples.  Modern RF component development is aimed at much higher frequency bands used for voice and data communications systems __ Circuit Design by Andy Mo

Improved CMOS RF PLL Sythesizer -  Lock range extended up to about 400:1 (50KHz, 2MHz).  Spectral purity improved, reduced reference frequency FM ripple.  Output level buffered to over 200mW RF power output.  Unecessary DiP switches removed, silly combinations not possible.  BMP format single-sided PCB foil available for downloading.  External VCO/Prescaler PCB to follow shortly (up to 150MHz)  __ Designed by Harry Lythall-SM0VPO

LTC Design Note: High input IP3 mixer enables robust VHF receivers -  08/29/14 EDN Design Ideas:  LTC Design Notes 515: An increasing number of applications occupy the 30MHz to 300MHz very high frequency (VHF) band.  Television and radio broadcasting, navigation controls and amateur radios are a few examples.  Modern RF component development is aimed at much higher frequency bands used for voice and data communications systems __ Circuit Design by Andy Mo

Mixer & Preamplifier for String Instruments -  Most of the small musical bands have up to four string instruments like guitars and violins.  The signal from the transducers of these instruments should be buffered and sometimes amplified before...__ Electronics Projects for You

Mix-It: an Easy-To Build 4-Channel Mixer -  Anyone can build this high performance four-channel audio mixer...__ SiliconChip

One-Transistor Amplifier/Detector -  An amplifier may be added to boost the audio level as shown below.  The current consumption of this amplifier is quite low and a power switch is not included.  Disconnect the battery when the receiver is stored for long periods.   __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Post Mixer Amp -  SSB Transceiver-Receiver Section:  The post mixer amplifier, makes up for the losses in the passive mixer and i.F.  port attenuator.  The transistor is a 2N4427, if you don't have one, try a 2N3866, 2N5109, on any similar, medium power VHF transistor.  The output transformer is 10 turns with a tap at 4 turns.  The core is the same, high permeability ferrite ring, used in other parts of this project.  The output supplies DC current for the RX/TX switching diodes at the SSB filter input __ Designed by EI9GQ homebrew radio

Simple Circuit Crystal Radio -  The crystal radio gets its name from the galena crystal (lead sulfide) used to rectify the signals.  A "cat's whisker" wire contact was moved about the surface of the crystal until a diode junction was formed.  The 1N34A germanium diode.   __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Simple Circuit Two-transistor Radio -  Here is a simple radio that was designed to minimize unusual parts; there isn't even a detector diode!  The sensitivity isn't as high as the one-transistor reflex but the simplicity is attractive.  Strong stations will provide plenty of volume __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

TL431 Crystal Radio Amplifier -  Here is a simple audio amplifier using a TL431 shunt regulator.  The amplifier will provide room-filling volume from an ordinary crystal radio outfitted with a long-wire antenna and good ground.  The circuitry is similar in complexity to a simple one-transistor radio but the performance is far superior.  The TL431.   __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Very High Gain Crystal Earphone Amplifier -  This simple, one-transistor amplifier provides a voltage gain over 1000 (60 dB) for driving a high impedance ceramic (crystal) earphone.  The high gain is achieved by replacing the traditional collector resistor.   __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

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  Signal Adder Circuits

 


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