Am-radio

Sat, 01 Dec 2012 00:12:00 MST

Coli data l1 0, L10, L2 = Tunong CQ

Wireless am microphone

Sat, 17 Nov 2012 00:11:00 MST

Transistor Ql and its associated components comprise a tuneable rf oscillator. The rf signal is fed to transistor Q2, the modulator. Operational amplifier ICl increases the audio signal and applies it through resistor R4 to the base of Q2. Tune an AM radio to an unused frequency between 800 to 1600 kHz. Tune Ll for a change in the audio level coming from the radio. Peak the output by adjusting L2

Short Wave Receiver

Sun, 04 Nov 2012 00:11:00 MST

Using a Signetics NE602 in a varactor-tuned front end, the circuit of a shortwave receiver can be very simple and yet g

AM reciever with TDA1072A

Sun, 16 Sep 2012 00:09:00 MST

This reciever uses the TDA1072A which is a complete AM reciever on a chip and it only requires comparitively few peripheral components to complete a high quality AM radio Circuit. Unlike some other AM radio ICs, a minimum number of external tuned inductors are used to preserve reasonable performance, selectivity and quality of output. Only two of these, an RF input transformer and a single winding oscillator coil need be tuned either capacitively or inductively.

Am demodulator

Mon, 06 Aug 2012 00:08:00 MST

Amplifying and limiting of the AM carrier is accomplished by the if gain block providing 55 dB of gain or higher with a limiting of 40 Âµ\. The limited carrier is then applied to the detector at the carrier ports to provide the desired switching function. The signal is then demodulated by the synchronous AM demodulator (1496) where the carrier frequency is attentuated due to the balanced nature of the device. Care must be taken not to overdrive the signal input so that distortion does not appear in the recorded audio.

Integrated-am-receiver

Tue, 26 Jun 2012 00:06:00 MST

A crystal Oscillator Ia used so that a narrowÂ·band hybrid IF filter can be used. This circuit has aerial and local oscillator circuits for a 27-MHz receiver

Frequency Counter

Fri, 20 Apr 2012 00:04:00 MST

Built around an Intersil 7216 frequency-counter IC, this counter has a basic range of 10 MHz, a 100-MHz prescaler, and an

AM IF filter

Mon, 18 Mar 2013 00:03:00 MST

Typical QRP receivers include Direct Conversion (DC) and simple Superheterodyne types. These receivers often have quite a wide AF bandwidth which can make inteligiblity somewhar restricted, especially under difficult QRM conditions. Many commercial amateur transcievers also suffer from this t.ex the Yaesu FT101B.

Regenerative AM Receivers

Wed, 13 Feb 2013 00:02:00 MST

The regen is basically an oscillator circuit with a gain control that allows the user to adjust the feedback to a point just below oscillation or, quite often, just above the critical level such that a small oscillation is present. The typical regen uses a tapped coil or additional windings to connect into the tuning tank and the tuning capacitor provides the total tank capacitance. The components are not critical and the values were pretty much the first ones found on the bench that were near the "right" value so don't hesitate to experiment. The transistor could be just about any small-signal NPN including the 2N4401, 2N3904, 2N2222, or others. The audio output is fairly weak and will need an amplifier to drive headphones or a speaker. See the audio amplifier page for suitable amps.

AM Radio

Tue, 22 Jan 2013 00:01:00 MST

A MW AM radio like those you buy, or used to buy. Use just BC549 trannies, with the BC559 complement being allowed in the audio output stage. Buying RF antenna coils, oscillator coils and intermediate frequency transformers would be cheating - wind your own. 9V battery powered. The transistor Q4 is biased up as a class A amplifier with some gain. The collector circuit provides feedback to the base via the tuned circuit. The two diodes D1 and D2 make a limiter to stabilise the amplitude across the frequency range. This is a differential amplifier comprising Q2 and Q3 with the two collectors connected together instead of going to individual loads to +BAT. The normal difference voltage output that you'd expect is therefore cancelled and you are left with the much smaller signal which is the effect of more current flowing in one transistor reducing the current flowing in the other, thus reducing its partner's gain and vice-versa.

AM Broadcast Transmitter schematic

Tue, 08 Jan 2013 00:01:00 MST

In this circuit, a 74HC14 hex Schmitt trigger inverter is used as a square wave oscillator to drive a small signal transistor in a class C amplifier configuration. The oscillator frequency can be either fixed by a crystal or made adjustable (VFO) with a capacitor/resistor combination. A 100pF capacitor is used in place of the crystal for VFO operation. Amplitude modulation is accomplished with a second transistor that controls the DC voltage to the output stage. The modulator stage is biased so that half the supply voltage or 6 volts is applied to the output stage with no modulation.

AM Radio Receiver schematic

Fri, 28 Dec 2012 00:12:00 MST

Pictured above is a little AM superhetrodyne receiver that covers the broadcast band from 550 Khz to 1650 Khz. The circuit employs the 8 pin Signetics balanced mixer IC (NE602) which converts the incoming RF signal to the standard 455 Khz IF signal and provides about 13dB gain. The IF signal is amplified by a single transistor stage and audio is recovered using a biased shotkey diode (5082) and JFET buffer transistor. The LM386 audio amp is used to drive a small 2.5 inch speaker at about 200 milliwatts. The circuit contains four LC tuned circuits, all of which need to be fine tuned to obtain good results. An oscilloscope and RF signal generator are useful, but the circuit can also be setup using local radio stations and an additional portable AM radio.

Inexpensive gadget tunes antenna for better DX

Thu, 20 Dec 2012 00:12:00 MST

The Antenna Construction of a long-wire antenna is simple. If you just remember and adhere to the following rules of safety. Never construct your antenna so that it could fall on power lines or they on it. Always use a lightning arrestor; this not only can save you equipment but may improve the signal, since it drains static electricity from the antenna. Never use wire or metal cable to support the antenna (1/4" nylon line is your best bet).

AM Receiver

Mon, 17 Dec 2012 00:12:00 MST

This is a compact three transistor, regenerative receiver with fixed feedback. It is similar in principle to the ZN414 radio IC which is now replaced by the MK484. The design is simple and sensitivity and selectivity of the receiver are good. All general purpose transistors should work in this circuit, I used three BC549 transistors in my prototype. The tuned circuit is designed for medium wave, but the circuit will work up to much higher frequencies if a different tuning coil and capacitor are used. I used a ferrite rod and tuning capacitor from an old radio which tuned from approximately 550 - 1600kHz.

AM To FM converter

Tue, 11 Dec 2012 00:12:00 MST

This circuit can be used to recieve AM stations in an FM radio. Is a regenerative circuit that samples AM signals of all frequency and retransmits them in the FM band or in TV band.

SW Loop Antenna

Sun, 18 Nov 2012 00:11:00 MST

The small single turn magnetic loop (SSTML) antenna consists of a single winding inductor, about 3 feet (1 meter) in diameter, and a tuning capacitor. A second loop, which is one fifth of the diameter of the large loop, is connected to the feedline and this small loop is positioned in the large loop on the opposite side of the tuning capacitor.

CXA1191 AM/FM Reciever

Sun, 18 Nov 2012 00:11:00 MST

The radio IC is in the middle of the board. Above the IC you will find a ceramic filter (10.7MHz) for the FM part. This filter is blue. At the top you will find the yellow AM IF filter. This filter is a 455kHz tuned filter. The slug is in yellow color. You can use this filter as a quadcoil because it is a LC unit tuned to 455kHz. There is two more cans. One is red, this is the AM oscillator (0-2MHz). The can with pink color is a quadcoil for the FM demodulation. This can is a LC unit tuned to 10.7MHz. At the right side you will find 2 tuning things. The one at the top is the volum control and the one at the bottom is a variable capacitor. Actually it is four tunable capacitor in one house. Most often there are two in the range 5-30pF and two with the range 10-130pF.

27MHz CW transmitter

Sun, 18 Nov 2012 00:11:00 MST

The original TX was designed to be only PULSE Modulated for a proportional R/C system, but I later used the same circuit to make an HF bands Amplitude Modulation (AM) transmitter using PA-Base Modulation. It eliminated the need for a modulation transformer; it can be driven with a simple Op-Amp amplifier. Frequency range of the original prototypes were as low as 1MHz and the top frequency was 40MHz. The circuit is the same, just the crystal and coils are changed. The CW output power is about 200mW at 29MHz. It is only 70mW Amplitude modulated, but modulation peaks can rise to 200mW with 80% modulation.

AM Receiver Using The NEC UPC2768GR IC

Fri, 16 Nov 2012 00:11:00 MST

A wide variety of low power wireless communication systems have surfaced in recent years. Automotive keyless entry, home security, bar code readers, and child monitors are just a few of the many applications for this technology. Most low power wireless systems transmit less than 1mW of power and operate in the FCC PART 15 band (260-470 MHz) where licensing is not required at such low power levels. Operating range varies from just a few feet (bar code readers) to a few hundred feet (garage door openers) depending on the application.

AM Radio with ZN414

Fri, 16 Nov 2012 00:11:00 MST

The ZN414 IC contains an entire automatic gain controlled AM receiver in a small three pin package. With only a few external components, a simple radio with excellent selection and reception can be constructed. Since the chip also uses a low supply voltage of only 1.3V, 3V coin cell battery can make for a physically small circuit with many covert uses. The chip has a wide bandwidth of between 150KHz and 3MHz, so by playing with values in the tuning circuit you can pick up a wide variety of signals.

AM power transmitter

Fri, 02 Nov 2012 00:11:00 MST

The circuit for a powerful AM transmitter using ceramic resonator/filter of 3.587 MHz is presented here. Resonators/filters of other frequencies such as 5.5 MHz, 7 MHz and 10.7 MHz may also be used. Use of different frequency filters/resonators will involve corresponding variation in the value of inductor used in the tank circuit of oscillator connected at the collector of transistor T1. The AF input for modulation is inserted in series with emitter of transistor T1 (and resistor R4) using a transistor radio type audio driver transformer as shown in the circuit. Modulated RF output is developed across the tank circuit which can be tuned to resonance frequency of the filter/resonator with the help of gang condenser C7.

AM reciever with MK484

Wed, 31 Oct 2012 00:10:00 MST

The basic MK484 (Replacement for the ZN414) connected in its minimum configuration as a radio receiver for the A.M. Broadcast band and the upper half of the United States' FCC Part 15 Lowfer (1600-1750 meter) band. Its a circuit straight out of the application note and I have fount it to be useful on the bench. Even more convenient that using the Radio Shack short wave receiver, mainly because the tuning is so broad on this that I don't have to tune precisely to hear the signal.

Pocket Radio AM / FM circuit

Mon, 15 Oct 2012 00:10:00 MST

Earphones, batteries are sold separately. AM / FM seems to be a common mold. But stamping is different. AM / FM E193577 UL94V0 board with the AM / FM etching printed circuit board manufacturers are the same. Shape is considered to be shared. (Design, sharing the production process design?). Radio FM transistor S9014, IC LA1800 is used. 100 AM, FM Radio and 2W IC Amp substrate incorporated into the case. Variable capacitor is used for the junk FM · AM variable condenser 2. FM section, and turned the proximity variable capacitor, AM has a distance as a measure of the local oscillator wrap, leads unavoidably variable capacitor, Sorudatoru (desoldering wire), and with the shield. Radio low-frequency portion, FM ANT has converted part of the circuit. Radio is the height of perfection impressed.??

ZN414 Portable Receiver

Thu, 11 Oct 2012 00:10:00 MST

An AM portable radio receiver made from the ZN414 IC. The ZN414 ic has now been replaced by the MK484 which is identical in performance and pinout. Designed around the popular ZN414 IC this receiver covers the medium wave band band from approximately 550 to 1600 KHz with the values shown. The coil and tuning capacitor may be taken from an old MW radio to save time. The ZN414 IC, has now been replaced by the MK484. The integrated circuit is a 3 pin, tuned radio frequency circuit, and incorporates several RF stages, automatic gain control and an AM detector.

Aircraft band / AM Receiver with PIC16F84

Sat, 06 Oct 2012 00:10:00 MST

Aircraft communication is still AM modulated and the frequency is about 110-125 MHz. What differ this construction from my two previous is that I have implemented many blocks into one circuit and therefore I will have superior performance with less components. The receiver is working with a Frequency Synthesizer which gives a very stable reception and it is easy to change frequency as well. The RF signal is first amplified before it enters mixer 1. To mixer1 is also a VCO (Voltage Controlled Oscillator). The tuning voltage to the oscillator is controlled by the PLL synthesizer. There is also a feedback from the output of the VCO to the PLL synthesizer. The synthesizer will control the VCO-voltage until the frequency is locked to the desired frequency you have programmed into the PIC circuit. The product of the mixer 1 is filtered into a standard 10.7MHz ceramic filter and then enter mixer 2. At mixer 2 the RF will be mixed with a constant frequency from a crystal (10.245MHz). The product will enter a new ceramic filter and finally into a AM demodulator which brings out the audio.

AM LOOP ANTENNAS

Thu, 27 Sep 2012 00:09:00 MST

The schematic diagram of an AM loop antenna is shown below. It consists of an inductive winding, which is supported on a frame, and a variable tuning capacitor that can be salvaged from a junk radio. The inductive winding consists of a primary, which forms a resonant network with the tuning capacitor, and a secondary "sense" winding that can be connected to a radio. In practice, however, the sense winding is not needed if the loop antenna can be placed near the radio - mutual coupling will take place with the antenna in the radio.

AM Transmitter

Sat, 15 Sep 2012 00:09:00 MST

This ircuit is deliberately limited in power output but will provide amplitude modulation (AM) of voice over the medium wave band. The circuit is in two halfs, an audio amplifier and an RF oscillator. The oscillator is built around Q1 and associated components. The tank circuit L1 and VC1 is tunable from about 500kHz to 1600KHz. These components can be used from an old MW radio, if available. Q1 needs regenerative feedback to oscillate and this is achieved by connecting the base and collector of Q1 to opposite ends of the tank circuit.

Amplitude Modulation AD9850 Direct Digital Synthesizer

Wed, 08 Aug 2012 00:08:00 MST

This application note will offer a method to voltage control or amplitude modulate the output current of the AD9850 DDS using an enhancement mode MOSFET to replace the fixed RSET resistor; and a broadband RF transformer to combine the DDS DAC outputs to produce a symmetrical AM modulation envelope. Modulation with reasonable linearity is possible at rates exceeding 50 kHz. The AD9850 DDS output current (20 mA maximum) is normally set with a fixed resistor from the RSET (Pin 12) input to ground. The DAC outputs are unipolar and complementary (180 degrees out of phase) of each other.

AM-Receiver for Aircraft comm (118.250MHz)

Thu, 02 Aug 2012 00:08:00 MST

The aircraft communication in Sweden is still Amplitud Modulated (AM). The local airport (Axamo) use the frequency 118.250 MHz. The reveiver I will explain is a tunable AM-receiver for this frequency. The receiver is instead manually tunable with some 100kHz around the 118MHz. The output from the receiver is a low level output (100-200mV) so you must connect it to some kind of amplifier. I will not explain how to build an audio-amplifier. The hart of the receiver is the Voltage Controlled Oscillator (VCO).

One Transistor Regenerative AM Receiver

Tue, 24 Jul 2012 00:07:00 MST

This classic design, revamped to use a transistor instead of a vacuum tube applies the principles of Regenerative Receivers-- which essentially means that the transistor stage has high levels of positive feedback at a certain frequency--the frequency of desired tuning. The stage is operated right below the point of oscillation.

Regenerative receiver for AM band

Wed, 18 Jul 2012 00:07:00 MST

The regenerative detector uses a field effect transistor (FET). Like with the better valve designs, feedback is controlled by a variable capacitor. A ferrite rod was used to allow reception of local stations without an external antenna. This FET stage forms a complete receiver on its own, but the audio output is quite low. The received audio is amplified by an NPN bipolar transistor. The gain of this transistor amplifier is sufficient to provide speaker reception of local stations in most areas. The 1k to 8 ohm transformer in the collector allows the set to be used with both low and high impedance headphones.

Simple Transistor Reflex Receivers

Sun, 15 Jul 2012 00:07:00 MST

This reflex radio project was inspired by Robert Bazian 's design. His reflex radio is the "darndest" thing I have seen and his spectacular results inspired me to come up with my own version! These designs are similar to two-transistor circuits used in some ancient Japanese "Boys Radios" except that the inter-stage transformer directly drives the speaker. The antenna coil is just 20 turns wrapped around four insulated posts as seen in the photos and shown in the diagram below. I used nylon posts but ordinary bolts covered with tubing would work fine. The dimensions are not particularly critical; those shown happen to fit inside the case I chose.

An AM RF Amp for Internal Antennas

Fri, 29 Jun 2012 00:06:00 MST

After the booster is built, open the radio and locate the antenna. Trace out the secondary winding (it does not go to the tuning capacitor!) and snip the leads. Connect these leads to the input of the booster. Run leads from the booster`s output to where the antenna secondary went. You must finally connect up the power and ground and mount the board to be finished. When that is done, turn on the radio and tune in a weak station above 1400. Adjust the set`s antenna trimmer and you are done. Happy Listening!

AM/FM/SW active antenna

Thu, 24 May 2012 00:05:00 MST

This circuit shows an active antenna that can be used for AM, FM, and shortwave (SW). On the shortwave band this active antenna is comparable to a 20 to 30 foot wire antenna. This circuit is designed to be used on receivers that use untuned wire antennas, such as inexpensive units and car radios. L1 can be selected for the application. A 470uH coil works on lower frequencies ( AM ). For shortwave, try a 20uH coil. The unit can be powered by a 9 volt battery. If a power supply is used, bypass the power supply with a .04uF capacitor to prevent noise pickup. The antenna used on this circuit is a standard 18" telescoping type.

Antennas for AM

Wed, 23 May 2012 00:05:00 MST

Outdoor antennas are less prone to electrical interference as they are situated away from household appliances. Although offering the best quality reception, outdoor AM antennas are not readily available from retailers as demand is low. Signal strength is usually strong within a radio stations coverage area, and antenna solutions for those outside the coverage area are specific to the individual location.

An AM RF Amp for External Antennas

Tue, 15 May 2012 00:05:00 MST

The first article had a 3PDT switch that not only acted as a power switch, but also allowed the user to bypass the amplifier. This would be very useful for areas with strong stations, to avoid overloading the receiver. The second article utilized a ferrite bar antenna, which severely compromised sensitivity. It did, however, include PCB artwork. I would suggest that this RF amp would be most helpful when used with the AM loop antenna. In this case, simply delete T1, which is mounted off the board anyway. C1 will serve as the tuning capacitor for the loop.

CW Decoder using PIC16F84

Thu, 10 May 2012 00:05:00 MST

The device is equipped with a 2x16 LCD display , the text shifts from left to the right starting from the end of the second raw. An inter-words automatic spacing function is provided, based on a regular timing of the pauses in the sent code. This function may be inhibited grounding the J pin if the device is used for training purpose or while receiving an improperly sent code. The audio input must be at least 100 mV pp, a clipper is provided to cut large signals. The band width is about 100 Hz and the center frequency may be adjusted between 700 and 1000 Hz by a trimmer.

HF SSB CW AM RF Linear amplifier

Sun, 29 Apr 2012 00:04:00 MST

This is a rather unusual QRP Power Amplifier design, with a wide frequency response; within three dB's from 300KHz to 30MHz. Overall gain is in the region of 16dB and the final output power may be well over four watts. The wide bandwidth is a result of the construction of the RF transformers, T1 and T2. These are wound on 2-hole ferrite balun cores as commonly found in the old fashioned valve TV sets (e.g. Phillips 4322-020-31520). Twist 2 lengths of 22 SWG enamelled wire together and wind as shown. Connect the end of the "A" winding to the start of the "B" winding. Use this junction as the centre-tap of the transformer.

An Unamplified Four Foot Box Loop

Fri, 20 Apr 2012 00:04:00 MST

Please find attached your copy of my four foot unampilfied box loop. It will tune from 525 kHz to about 1710 kHz covering the entire Broadcast Band. The umbrella stand described in the article is the type you would use for an outdoor umbrella. I fill mine with sand to keep it sturdy You will also notice a lack of metal hardware in this design. This was done on purpose to keep the antenna`s pattern as clean as possible. Other designs you may see have a lot of metal in them and this will lower their ability to null and to pick up weak signals. This is a DX`er`s loop.

AM receiver

Tue, 17 Apr 2012 00:04:00 MST

This is a description of an experimental AM receiver for VLF. It is crystal controlled to receive 181.818 kHz (more or less) and operates as either a single conversion superhetrodyne or a direct conversion receiver. The bandwidths are expected to be 15 Hz to 3.5 kHz in superhet mode and 15 Hz to 10 kHz in the direct conversion mode. Operation is from a single +5 volt regulator and it can be powered from a 9 volt radio battery or other source of +8V or higher. The reason I built this was to verify some of my assumptions about these components would work together, having had numerous discussions of the SA-612/MK-484 and SA-612 direct conversion receiver concepts over the last year or so with my friend Jeff, besides that, I want to have a direct conversion receiver on hand for some planned experiments.

Medium Wave Active Antenna

Sat, 14 Apr 2012 00:04:00 MST

This circuit is designed to amplify the input from a telescopic whip antenna. The preamplifier is designed to cover the medium waveband from about 550Khz to 1650Khz. The tuning voltage is supplieb via RV2, a 10k potentiometer connected to the 12 Volt power supply. RV1 is the gain control allowing weak signals to be amplified or strong signals to be attenuated. Finally this active antenna can be used on other bands by changing the values of the 330uH coils. To perform on multiple bands switches or relays can be used to change the value of the coils.

eSyndiCat Directory v2.3.05

Pulse-Frequency Modulated Receiver

Am Envelope Detector

Short wave radio for PC

Am-radio

Wireless am microphone

Short Wave Receiver

AM reciever with TDA1072A

Am demodulator

Integrated-am-receiver

Frequency Counter

AM IF filter

Regenerative AM Receivers

AM Radio

AM Broadcast Transmitter schematic

AM Radio Receiver schematic

Inexpensive gadget tunes antenna for better DX

AM Receiver

AM To FM converter

SW Loop Antenna

CXA1191 AM/FM Reciever

27MHz CW transmitter

AM Receiver Using The NEC UPC2768GR IC

AM Radio with ZN414

AM power transmitter

AM reciever with MK484

Pocket Radio AM / FM circuit

ZN414 Portable Receiver

Aircraft band / AM Receiver with PIC16F84

AM LOOP ANTENNAS

AM Transmitter

Amplitude Modulation AD9850 Direct Digital Synthesizer

AM-Receiver for Aircraft comm (118.250MHz)

One Transistor Regenerative AM Receiver

Regenerative receiver for AM band

Simple Transistor Reflex Receivers

An AM RF Amp for Internal Antennas

AM/FM/SW active antenna

Antennas for AM

An AM RF Amp for External Antennas

CW Decoder using PIC16F84

HF SSB CW AM RF Linear amplifier

An Unamplified Four Foot Box Loop

AM receiver

Medium Wave Active Antenna