Using AD9835 DDS chip with BASIC-52
AD9835 is a DDS (direct digital synthesis) chip from Analog Devices. It contains a phase accumulator, sinewave table, and 10-bit D/A converter. In can be used f...
Cyclotron II
The white feedthroughs are for the attachment of the RF high voltage to the D`s (not shown). The copper pipe normal to the pipe is the vacuum line. The D`s have...
double sideband suppressed carrier modulator
The basic current allows no carrier to be present in the output. By adding offsets to the carrier differential pairs, controlled amounts of carrier appear at th...
super simple shortwave receiver circuit
Integrated circuit Ul (an NE602 double-balanced mixer) is a combination oscillator and frequency mixer. Signals from the antenna input (at Jl) are fed through d...
carrier current fm receiver
Input signals from the power line are coupled through C23 and R19 to the input filter network. C23 must be rated at 600 volts. Switch 52 is used as an attenuato...
Regenerative AM Receivers
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, ...
optimized 6 element uhf yagi antenna
The elements diameter of the antenna may vary between 5. 8mm and the dipole diameter may vary between 8. 12mm (12mm recommended) without the need of changing an...
loop antennas
A loop antenna is a radio antenna consisting of a loop (or loops) of wire, tubing, or other electrical conductor with its ends connected to a balanced transmiss...
broadcast band rf amplifier
The circuit has a frequency response ranging from 100Hz to 3 MHz; gain is about 30 dB. Field-effect transistor Q1 is configured in the common-source self-biased...
The Omega passive receiver
The idea of the passive receiver is more than 100 years old. The first receiver type that is known to detect radio energy is the coherer type. The coherer inven...
varactor diodes circuits
The curves for a capacitor are all markedly non-linear and this property can be used as an element in a circuit to modulate, demodulate and multiply frequency. ...
VACUUM TUBES in UHF circuits
The use of a quarter-wave parallel-wire line as a tuning unit has been discussed in the chapter on Short-Lines, where it was pointed out that these " circuits "...
Deluxe Crystal Controlled Transmitter
A high quality QRP transmitter, which I have named as NEXUS 6, in my try to explore the issues related to extremely narrow bandwidth communication. It is not ju...
Description of an active reversible in-phase/quadrature modulator carrying out frequency UDC
Circuit schematic of the UDC containing only dispersive components. The two low-frequency series LC resonators (with LA=LB and CA=CB) are fed by two input semi-...
N5ESE-built TenTec 1315/1330/1340
Simple modifications I`ve done on these rigs, to overcome some common shortcomings. Not all kits need these mods, but many do. Some overcomeminor inconveniences...
N5ESEs QRP Dummy Load With Built-in RF Detector
This is yet another variation on the "parallel resistor" dummy load. [Go -here- for a discussion on dummy load theory]. This is another one I built during my in...
FM Wireless Mike
FM wireless Mike is a small electronic project based on a radio transmitter. It is a wonderful idea to make a wacky talky through which you can talk to your fri...
fm radio receivers
An AM receiver relies upon the original carrier signal (station frequency) having been amplitude modulated. This means the original amplitude (strength) varies ...
MW0LLO RF Milliwatt Meter
This project, based on an article published in the February 2008 edition of Radcom (the magazine of the Radio Society of Great Britain) is for a meter with a 50...
FM Mod on SMR-4 MKII
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