Wiring Schematic Diagram

The circuit diagram shown here is of 12V DC fan speed controller using the IC LM2941CT which is a low drop out 1A voltage regulator. The IC has a dropout voltage as low as 0.5 and has also many useful features like power supply reverse protection, thermal protection, short circuit protection etc. The maximum output current the IC can source is 1A.

The 12V DC supply is connected between the Vin (pin4) and ground (pin3) of the IC. The load, which is the fan, is connected across the Vout (pin5) and ground (pin3) of the IC. The network comprising of potentiometers R1, R2 and resistor determines adjust current (Iadj) of the IC. By varying the Iadj using the POT R2 we can adjust the output voltage of the IC and hence the fan speed.

This voice or sound recorder/playback built with IC ISD1012, ISD1016 and ISD1020 which are produced by ISD and allow sound voice recording and play-back. The last 2 digits show the maximum legth of recording time in seconds. this chip has many features like automatic gain control, anti aliasing filter, built in audio amplifier and smoothing filter. The IC is fully compatible to microprocessors and can be used for a myriad of applications. The voice is stored in their natural form in the non-volatile memory cells inside the IC which enables a high quality reproduction. T

Voice Record and Playback Circuit Using IC ISD1020A

The circuit is designed as per the application diagram in the datasheet. Pin23(CE) is the chip enable pin and it has to be held low using switch in order to perform a record or playback cycle. Pin 27 (P/R) is the playback/record pin and a high level on it selects a playback cycle while a low level on it selects a record cycle. The selection can be done using the switch S3.The pin 24 (PD) is the power down pin. It has to be held high using switch S2 in order to pull the device to a extremely low power mode while there is no recording or playback (idle state).The resistor R1 and capacitor C1 determines the release time of the internal AGC circuit. The resistor R5 and capacitor C5 connected across the pin 20 and pin 21 provides an additional cut-off to the low frequency end of the voice pass band.

This circuit is to setup home-cinema set adjusting all the loudspeaker outputs to the same level when heard from the listening position.In practice this device is a simple (though linear and precise) 100µAac millivoltmeter.

The precision of the measure is entirely depending on the frequency response of the microphone used but, fortunately, for the main purpose of this circuit an absolutely flat response is not required. Therefore, a cheap miniature electret microphone can be used.

The circuit is based on non- inverting amplifier based on op-amp CA3140 (IC1).The sound picked by the condenser mic will be amplified by the IC1 and rectified by the bridge D1 to drive the meter M1.The deflection on the meter will be proportional to the pressure of the sound falling on the mic.The switch S1 can be used as an ON/OFF switch.

Here is A pre-amp circuit for high impedance type electric guitar pickups. The circuit is given based on a uA741 operational amplifier. The ua741 is connected as a non-inverting amplifier. The POT R1 can be used as a volume knob controller.The R6 can be used as a controller. The switch S1 is used to produce "bright" or "soft" sound effects.

Note:

This phase control circuit can be used for controlling the power supplied to an AC load. AC waveform is controlled by the phase control circuit, cutting cycle to provide full cycle, half cycle, the cycle to zero, or somewhere in between. Maybe you can tell which is very similar to an dimmer circuit, but switching and zero crossing of the waveform is synchronized.

Triacs not to suffer power losses, thus increasing overall efficiency, there is the advantage of the power of the method of zero crossing. This control circuit is adapted phase for heating the filaments, brushed AC motor, or incandescent lamps. U208B acts as a phase control circuit in bipolar technology with monitoring of the power supply internally. Uncontrolled output pulses avoided by internal controls, tension builds. Further more, it has the sync voltage and internal power. It is strongly recommended as an inexpensive control in open loop.