Wiring Schematic Diagram

A square wave generator with IC UA741 range shown here.The circuit uses positive feedback to the Schmitt trigger action and negative feedback to measure the time of the waveform.

Let us assume that the output is high and the capacitor C1 is fully discharged.C1 now begins to charge through R2 and C1 R1.When tension rises above the junction of R3 and R4, the output changes rapidly totally negative voltage.C1 Now begins the unloading and reloading in the direction.Again contrast, when the negative voltage across C1 falls below that at pin 3, the circuit is returned quickly to totally positive repetitions value.The output endless cycle.

The square wave frequency can be varied by varying POT R1.The frequency range of the circuit depends on the value of R3, R4 and C1.

After several requests of the correspondents, the decision to design a headphone amplifier 9V power was finally taken. The main requirement was to feed the circuit by a common, PP3 (transistor radio) alkaline batteries. Therefore, the circuit implementation of a low current draw was absolutely necessary, while retaining high quality.

The emergence of low-noise 5534 operational amplifier at a reasonable price was much appreciated by audio designers. Now it is difficult or impossible to design a specific phase that has the performance of 5534, without the complexity unacceptable. 5534 operational amplifiers are available from various sources, in a conventional 8-pin dil format. This version is internally compensated for gains of three or more, but requires a small external capacitor (5-15pF) for unity gain stability. The 5532 is a convenient pack of two 5534s in an 8-pin device with internal unity gain compensation, since there are no spare pins.

The 5534 / 2 is a low distortion and low noise device also has the ability of low-impedance load to full voltage swing, while maintaining low distortion. It is fully output short-circuit. Therefore, this circuit is carried out with a single 5532 chip forming a pair of stereo amplifiers, invest, have a current gain of about 3.5 alternating and capable of delivering up to 3.6 V peak to peak 32 Ohm load (corresponding to 50mW RMS) less than 0.025% total harmonic distortion (1 kHz and 10 kHz).

Considering that the average current drawing a power of 15 mW per channel is about 12-13mA (both channels driven), this headphone amplifier will become a "must" for many DIY enthusiasts who need a device High quality, high performance laptop.

Need a tone control, this module can be inserted into the chain between the Control Center and power amplifier. The circuit is based on an original design by Reg Williamson, published in Electronics World + Wireless World, circuit ideas, January 1991.

The tone control circuit will take the form of any of the traditional low treble adjustment, or the type of shelves, which is similar to a "tilt" control, but with separate bass and treble. Asymptotic slopes for both are about 4dB/octave, but begin to level off at 100 Hz and 10 kHz, with a maximum of ± 15 dB at the ends of the audio band.

Component values ​​in parentheses are the shelving of control. In this case, the platform starts around 250 Hz and 4 kHz, flatten to a maximum of ± 6dB an octave above or below the central point is 1 kHz. Reactive elements for low-end includes a generalized impedance converter, which simulates an inductor in series with a resistor (spinner).

When set to the centers of their respective electrical controls, equalizers reactive elements are almost out of circuit. With these settings, the circuit behaves as a unity gain amplifier with 100% negative votes. Still, the reactive elements can be changed completely with a DPST on / off.

As with the other modules in this series, each electronic card can be fitted in a standard: Hammond extruded aluminum cases are well suited to accommodate the tables in this preamp. In particular, instances of size 16 x 10.3 x 5.3 cm or 22 x 10.3 x 5.3 cm look very good when stacked. See below an example of the possible arrangement of the front and back of this module.

LM12 operational amplifier can output currents up to 10A. The LM12 in encapsulated in TO-3 with 4 pins, can support up to 800W and has enough internal protections to prevent slacks from over-currents or over-heating.

You can use LM12CL with 30 V maximum voltage or LM12C with 40V maximum. The L1 coil has 40 turns 1mm copper, coiled over R4. If you use LM12CL it is recomended to have toroidal transformer 2 x 22V. The output must be between 7 and 12A. Filtering capacitors must have at least 20.000 uF. LM12 must be mounted with screws on a big heatsink (=< 1.50 C/W) and electric isolated form the heatsink.

via: electroschematics.com

FM transmitter circuit very stable and simple given here. With an adaptive antenna, the transmitter can reach a range of about 200 meters. Transmitter met this year and got a few good results. Let's see how the circuit.

A condenser microphone (K1) is used to collect the sound transmitted. The capacitor C1 is a DC decoupler and the audio signal is coupled to the base of Q1 which connects a preamplifier.R2 and R3 are the resistances of polarization of Q1. Amplified sound signal will be available at the collector of Q1 and, together with the emitter of transistor Q2 through capacitor C4 and inductor L1 1mH.

C4 capacitor decouples the DC component of the preamplifier output. Q2 does the work of the oscillator and modulator. Inductor L2 and capacitor C5 variable tank circuit is necessary to create oscillations. Capacitor C6 is the feedback capacitor. The FM modulated wave will be available at the collector of Q1 and is transmitted through the antenna A1.