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Basic Vox - A recent look at some of the budget priced HF transceivers revealed that they were missing a VOX. Although most of these budget priced transceivers performed admirably, it would certainly be nice to have VOX capability. Figure 1 is a basic VOX circuit which will perform very well once the VOX level is set correctly. This circuit is low cost and all parts can be found at your local Radio Shack store __ Designed by Radio Amateur Society of Norwich BCD Receiver without Coils - The radio consists of two phase-shifting transistor stages (T1 and T2) and a RF amplifier (T3). The gain of T1 is almost one (R4/R5). Phase shift of this stage is 90 degrees at a frequency determined by P2 and C4. The second stage (T2) is identical to the first; the frequency of 90 degrees phase shift (electroninc design) __
Beat frequency oscillator for AM /SW radio receivers - schematic only__
Bidirectional Current Source - The LT1990 is a differential amplifier with integrated precision resistors. The circuit shown is the classic Howland current source, implemented by simply adding a sense resistor. __ Linear Technology/Analog Devices App Note, Mar 31, 2010
Bipolar Regenerative Receiver - Contrary to what some radio experimenters think, a bipolar regenerative design can be made to work efficiently. The major concern is the low input impedance of the detector-amplifier bipolar. __ Designed by Ramon Vargas
Bipolar transistor mixer - Ham Radio - V-U) HF AMPLiFiER - Schematic __ Designed by Guy Roels ON6MU
Bipolar, Ground Referenced, Single-Ended Signal Interface to Unipolar, Differential Input ADC - Differential amplifiers are useful for providing the input to a single supply differential ADC from a bipolar ground referenced input source. All of the signal level shifting and gain requirements can be adjusted with external resistors. __ Linear Technology/Analog Devices App Note, Mar 16th 2010
Bob Sickel's Antenna Switch for Dicke Switching Receivers - This is a Radio Astronomy Project __ Designed by Radio-Sky Publishing
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
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
Broomstick Crystal Radio - i construct this one as a “beginner’s radio” with loop antenna. I don’t know if broomsticks have the same length everywhere, but those I found had 1, 20 M, which is sufficient to mount a loop with about 30 cm of side. its small but with a simple ceramic earpiece I can get the 5 MW stations in my city. I guess it is a good “first radio” project because for children it’s hard sometimes to install a long wire antenna. Well, when I was a kid nobody cares when I was walking through the roof, but now times are different. __ Designed by Marcos Kusnick
Bug Detector (mini) - This project is a handy piece of TEST EQUiPMENT. You can never have enough assistance when designing FM bugs. The first thing you need to know after putting a bug together is the fact it is transmitting.
This project gives you this indication. Once you know a bug is transmitting, you can work on getting the best output power and adjusting the frequency to a blank spot on the dial. __ Contact Colin Mitchelltalking @ tpg.com.au
Bug Detector with Beep - This circuit is not open for discussion. Although working perfectly, it was experimental. I will answer no emails in regards to this circuit. if you are looking for a more serious and reliable bug detector, . __ Designed by Tony van Roon VA3AVR
Build a 100Khz Crystal Calibrator - There is a great deal of old amateur gear which many amateurs have decided to restore and bring back to life. While much of the early amateur transceivers work just fine they usually lack a digital readout and must rely on analog dials for tuning. The problem of dial calibration is complicated by the non-linear effects of tuning capacitors. This month's circuit is a 100Khz crystal calibrator using an inexpensive microprocessor crystal and CMOS
IC 's which are readily available at Radio Shack. __ Designed by N1HFX
Build a Crystal Set (Simple Circuit AM radio receiver) - Building a crystal set may lead you to a lifetime of electronics addiction. I have heard so many tails that there is no doubt that a crystal set is the gateway drug to electronics. in these modern times it's not easy to find parts. Some of you may be afraid of winding coils (it took me many years to get over helixaphobia. However my investigations have LED me to the inescapable conclusion that winding coils is the best way. __ Designed by Max Robinson
Build a Simple Circuit AM Radio - This simple AM radio can built in two forms. One is shirt pocket size, not much larger than an Android phone, which drives headphones or ear-buds. The other is a retro-style mantel radio with a hand-span dial and a 100mm (4-inch) loudspeaker in a basic timber cabinet.__ SiliconChip
Build a Simple Circuit crystal set - amateur radio construction projects. __ Designed by Peter Parker
Build a Two Channel Signal to Noise Voter - As hand-held transceivers (H-Ts) become smaller, and low power, battery conserving operation becomes more popular, the disparity between the transmitting range of a typical 100 watt repeater compared to the repeater accessing range of a typical 1 watt or less H-T becomes more and more apparent. How often have you found it difficult (or impossible) to access a repeater with a low power H-T even though you can hear the repeater at full quieting? This can happen even if the repeater is equipped with a high sensitivity, state-of-the-art receiver. __ Designed by Mark Kolber WB2WHC
Build the "Aussie-3" Valve AM Radio - So you thought valve technology was dead! Well it is - but we have exhumed enough of it to produce a 3-valve radio which has quite a respectable performance. it is a superheterodyne circuit, based entirely on readily available components. it is suitable for moderately-experienced constructors - even those who've never touched a valve in their lives! __ SiliconChip
Build your own superheterodyne receiver - 08/01/1996 EDN Design Ideas: : Easy to build, 2 chip Superhetrodyne for the aircraft band. Cell phones aren't the only devices to benefit from ever-smaller and more highly integrated communications-IC technology. The simple, three-IC superheterodyne radio in Figure 1 can receive stations in the 4.5- to 10-MHz range from around the world with only a 10-ft antenna. A superheterodyne radio works by mixing the incoming RF signal with a local-oscillator (LO) signal to produce an iF. Design by Steven Hageman, Hewlett-Packard, Santa Rosa, CA
Build Youself a Service Monitor? - For creating a COS signal on radios that don't have one. This is a VOX circuit that uses a FET as the input amplifier to avoid loading down the source. __ Designed by Tom Alldread VA7TA
Building a simple crystal radio - A crystal radio is the distilled essence of a radio. it has very few parts, it needs no batteries or other power source, and it can be built in a short time out of things you can find around the house. __ Designed by Simon Quellen Field
Building an RF Remote Control System - With a handful of inexpensive components, a little creativity, and the power of PicBasic, you can build some pretty outstanding robotics creations as Rob Arnold proves with his Ruf-Bot project. __ Designed by Rob Arnold |
