Schematics or Circuit Diagrams that aid learning.

The only way to improve the reception of FM-signals or particularly of stereo FM-signals under disadvantageous receiving conditions is to amplify the antenna signal. This should be made directly at the antenna, since the loss is increased meter by meter of any cable. In most cases higher line attenuations can be expected than usually calculated. Even receivers with an additional noise figure of zero do not show any improvements of the signal-to-noise ratio becomes too low because of a long transmission line. Therefore it is practically useless to require extremely low noise figures only for the receivers.

To avoid interferences of signals received from stations of other bands it is propitious to amplify the FM-band only. The band amplifier shown in Fig. 1.3 is connected directly to the 60 ohm output of the FM-antenna, i. e. it is placed at the top of the antenna pole. The matching is achieved by the input band-pass connected to the base of transistor BFT12, being a typically linear silicon transistor for broadband amplifiers. The output filter matched accordingly to a 60 ohm coaxial line is connected to the collector. The operating voltage of 15 V can be supplied by the coaxial line.

Fig. 1.3

Antenna-amplifier with BFT 12 for FM-range

Technical data:

  • Power gain Gp = 22 db
  • Noise figure F = 3.5-4.0 db or 2.2-2.5 KT0
  • Input and output reflexion coefficient |r1| and |r0| <= 0.3
  • dim(60db) at Vout = 680 mV
  • dim(50db) at Vout = 1000 mV

Optimum operating point of minimum intermodulation

Ic =~ 80 mA Vce =~ 7-7.5 V
Supply voltage 15 V

Coil data:

Vogt coil former, ordering code: Sp 3.5/16.6-2048C
Core: U17

  • L1 : 5 turns Cu 0.6 mm \o
  • L2 : 3 turns Cu 0.6 mm \o
  • L3 : 3+2 turns Cu 0.6 mm \o

Choke Ch1 = Ch2: 20 turns Cu L 0.3 mm \o, cross section of winding = 4 mm

Credits –

Antenna-amplifier with BFT 12 for FM-range
from Design Examples of Semiconductor Devices – Siemens

This is one IC that is like a E-LEGO, this along with Op-Amps and other components can make many interesting projects. Probably the very first Datasheet and Application Note of 555 t he e-lego.

Signetics made the 555,  On some pins like Control Voltage it responds to analog signals and on Reset and Output the signals are Digital like. The 7555 a CMOS version consumes lower power and oscillates at higher frequencies.

NE555 Applications and Specifications

555 trigger voltage cartoon

This evergreen or perennial chip is the favorite among students and hobbyists who want to learn electronics. Here is an original datasheet from Signetics i found online, it has very nice illustrations which will act as an appetizer for learning this science.

I want students to look into these specs pages as it will make your study more invigorating

555 Timer based Circuits – delabs

Signetics made the 555, This is one IC that is like a E-LEGO, this along with Op-Amps and other components can make…

555 The most Incredible Chip

Create an innovative 555 design today, the 555 should be the heart of the circuit. Here are some pages having 555…

I  was enlightened about this Battery Less wonder. This is a boon for rural areas and an emergency tool which depend only on your will and your tendons. I found this bright flash of information when i was looking for supercap vendors.

Learn about Supercaps, dynamo and White LED

Richard J. Nelson on the LED Forever Flashlight. – The future of low power lighting is in the use of the Light Emitting Diode, LED. Sooner or later you will buy one or more LED lights or lamps. The two primary advantages of an LED light source is it’s efficient light generation (exceeding that of fluorescent lamps) and long life, typically 100,000 hours. That is 50 to 100 times more life than most of the bulbs in your house.

Learn about the Eternal Torchlight

This is a Linear Dynamo LED Torch which uses a SuperCapacitor to store the energy. Easy to repair and maintain if necessary.

It uses no batteries and requires only the single LED included. You can even leave the flashlight unused in your car’s glove box for years and you’ll always get that all-important light when you need it most. Forever Flashlight lll pays for itself quickly by saving you the cost of batteries and bulbs.

Bill Bowden’s Circuits is one of the oldest Web Reference, it was hosted by CompuServe homepages and later moved to his own domain website.

A small collection of electronic circuits for the hobbyist or student. Site includes over 100 circuit diagrams, links to related sites, commercial kits and projects, newsgroups and educational areas.

Hobby Circuits - Bill Bowden

Most of the circuits can be built with common components available from Radio Shack or salvaged from scrap electronic equipment…….

Hobby Circuits – Bill Bowden

Some of the Highlights in this website

  • 32.768 KHz Oscillator Using A Common Watch Crystal
  • 40 LED Bicycle Light (555 Timer – 6 volt)
  • Descrete LED fading circuit using 5 transistors
  • Mechanical Wall Clock Quartz Synchronizer
  • Neodymium Magnet Single Pole Motor
  • Variable Voltage and Current Power Supply
  • Micro Power AM Broadcast Transmitter

Radio-Electronics was an American electronics magazine that was published under various titles from 1929 to 2003.You can Read them all here .

Radio Electronics Magazine at The Internet Archive

Recently i found a collection of those mags at …..

Radio Electronics Magazine at

Hugo Gernsback, sometimes called The Father of Science Fiction, started it as Radio-Craft in July 1929. The title was changed to Radio-Electronics in October 1948 and again to Electronics Now in July 1992. In January 2000 it was merged with Gernsback’s Popular Electronics to become Poptronics.

Gernsback Publications ceased operations in December 2002 and the January 2003 issue was the last.

Over the years, Radio-Electronics featured audio, radio, television and computer technology. The most notable articles were the TV Typewriter (September 1973)[1] and the Mark-8 computer (July 1974). These two issues are considered milestones in the home computer revolution.

Radio Electronics Magazine at SWTPC

Radio-Electronics was aimed at electronics’ professionals such as radio and TV repairmen. And they were men, the tag line on the cover was “For Men with Ideas in Electronics”.

Radio-Electronics & Electronics Now

Radio Electronics was the “new” name for Radio Craft magazine.. Hugo Gernsback, sometimes called The Father of Science Fiction, started it as Radio-Craft in July 1929. The title was changed to Radio-Electronics in October 1948. In July of 1992 transitioned to “Electronics Now

There are ten categories of schematics, a unified circuit analysis, design and theory page, and also a practical electronic section. The simulation section features the “TINA” and “Circuit Maker” programs. (this is a first generation website )

Circuit Exchange International

Some interesting sections are Alarms & Security Circuits, Control & Interfacing, Radio Circuits, Power Supplies & Circuits, Timing Circuits.

Circuit Exchange International


First created back in March 1999 and intended for electronics hobbyists, engineers and enthusiasts everywhere. Currently there are 310 schematics divided into 11 categories. Also included are tutorials, design and simulation sections.  – Andy Collinson