BBE Sound Maximizer

Pseudo State-Variable Filter
Front Panel Controls
Pin numbers refer to the pins on the NJM2153 IC package. Not all circuit elements are available outside the package.
All resistors are 1% tolerance. Capacitors less than 0.1 uF are 5% tolerance. Capacitors >= 0.1 uF are 20% tolerance.
The functionality of the BBE 482i could probably be reproduced with a few dollars worth of off-the-shelf parts. Circuit Analysis of BBE 482i "B" Channel 0

Wireless Microphone Circuits

FM Wireless Mike: low power frequency modulated transmitter using two transistors. The circuit works with 9v power supply. . (Circuit added 9/04)

Low-power FM Wireless Microphone: Small, wireless microphone that will transmit a whisper to a nearby (1/4 mile radius) FM radio, tuned to the 100 - 108 Mhz region of the dial. Powered by 9-volt battery, and features hand-wound inductor. This Detailed Description contains theory of operation, construction tips, and some testing procedures. (circuit design added 10/06)

Micro Spy With FETs: (Electronic Schematic / circuit added 4/02)

Micro Spy With TTL: (Electronic Schematic / circuit added 4/02)

Micro Spy With USW: (Electronic Schematic / circuit added 4/02)

Miniature FM Transmitter: (Electronic circuit added 4/05)

Miniature FM Transmitter #1: (Electronic Schematic / circuit added 4/02)

Miniature FM Transmitter #2: (Electronic Schematic / circuit added 4/02)

Miniature FM Transmitter #3: (Electronic Schematic / circuit added 4/02)

Miniature FM Transmitter #4: (add 9/04)

Miniature FM Transmitters #5: (added 6/03)

Miniature MW Transmitter: circuit diagram of simple medium wave transmitter using BF494B. This simple transmitter have a range of 200 meters. . (Circuit added 9/04)

Wireless Microphone #4: (Electronic circuit added 4/05)

100 Watt Power Amplifier

General Description

This is an exceptionally well designed amplifier, with a lot of power reserve, high fidelity, low distortion, good S/N ratio, high sensitivity, low consumption and full protection. Having all these almost ideal characteristics this amplifier is likely to become the basic building block of your future high fidelity system, or it can also become the element that will upgrade your existing system.

How it Works

The circuit works from a symmetrical ñ40 VDC power supply and draws a maximum current of 2.6 A. The input circuit of the amplifier is a differential amplifier built around Q4 and Q5 that employ DC feedback thus preventing any DC voltage from appearing across the speaker with the usual destructive results. Q11 acts as a current source and ensures that the input stage draws a constant current of 1 mA. The signal which appears as a voltage drop across the resistor connected in series with the collector of Q4 is used to drive the DARLINGTON pair Q3, Q2 which together with the constant current source of 7 mA that is Q10, form the driver stage. This stage operates in class A and is driving the complementary output stage Q1, Q9. The transistor Q7 is used to balance the circuit at different temperatures and must be mounted on the heatsink between the out put transistors. The feedback loop which consists of R8, R9, C2, C3 provides AC stability to the circuit. The circuit also incorporates a protection stage that makes it virtually indestructible. This protection circuit is built around Q6, Q8. If for whatever reason the output remains connected on one supply rail and the common the output is also protected from high DC voltages that could burn the speakers. The supply rails should be protected by 2 A fuses for the 8 ohm version and 3 A for the 4 ohm.

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