Datasheet BC549 Philips
http://www.datasheetcatalog.org/datasheet/philips/BC549.pdf
 
 

137kHz Low Power Transmitter by DF3LP
This is a very short description of my tiny low power cw transmitter for long wave. Depending on the PI-Filtercomponents and voltage for the final stage this transmitter would be able to reach the 100 Watts output level.
http://www.qsl.net/df3lp/projects/lftx/index.html

A very simple VLF Pocket receiver by DJ1WF
The following receiver concept may give an idea how to build a tiny and sufficiently performant RX without using expensive filters.
http://www.vlf.it/fritz/pocketrx.html

Frequency Divider by one transistor BC549
This circuit designs to upward for divide by the frequency of a signal input , give down left just the half then to export come to the way output.
http://www.eleccircuit.com/frequency-divider-by-one-transistor-bc549/
 

Low Power FM Transmitter
This low power fm transmitter is designed to use an input from another sound source and transmits on the commercial FM band. This low power fm radio transmitter it is actually quite powerful…
http://www.electroschematics.com/2233/low-power-fm-transmitter/

Multipurpose VFO For Your Rigs by VU3NSH
The Frequency instability in VFO stage is a common problem. This is usually occurred in VFO's due to low “Q” of the tank circuit, capacitors real value, power supply regulation, stray capacitance, lead inductances and over feed back levels etc.
http://www.hamradio.in/circuits/vfo.php

Simple audio amplifier
This simple circuit can be used to boost the signal sources that are not able to excite your amplifier, or from entering your PC, such as microphones for low and medium impedance, sound-heads, guitar pickups, guitar, etc.
http://xtronic.org/circuit/amplifier/circuit-audio-preamplifier-bc549-transistor-pcbs-volume-control/

Video amplifier splitter by transistor BD137-BC547-BC557
This is the video amplifier circuit or the video splitter circuit, it is designed to take video signal is stronger. Compensate for the loss of signal, and is video splitter video, which can connect up to three outputs. so is suitable for display on several television screens at the same time too.
http://www.eleccircuit.com/video-amplifier-splitter-by-transistor-bd137-bc547-bc557/