4 MHz Amplitude Modulated RF Source - A while
back I needed an amplitude modulated signal source
at 4 MHz. This circuit was literally thrown together
with parts laying on the bench. I built it dead bug
style on a piece of copper clad board. It should
work with little or no modification, other than get
it to oscillate, and at higher frequencies, you
might have to reduce the capacitor values a little.
AM DSB Transmitter for Hams - circuit diagram of
simple double side band suppressed carrier (DSBSC)
transmitter for hams. Circuit uses crystal
oscillator, crystal can be switched for multi band
operation.
AM Receiver - 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.
AM Transmitter (Andy Collinson) - 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.
AM/FM/SW Active Antenna - This circuit shows an
active antenna that can be used for AM, FM, and
shortwave SW. On shortwave band this active antenna
is comparable to a20 to30 foot wire antenna. This
circuit uses receivers that use untuned wire
antennas, such as inexpensive units and car radios.
Micro Power AM BroADCast Transmitter - 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.
Pi Filter has Sharp Notch - Electronic Design -
Simple filter network makes a great low-pass filter
having a sharp notch just outside passband. Can be
implemented as active filter using GIC circuit.
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