Alarm circuit for snoring prevention
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Simple Alarm Circuit Keeps Wandering Children
The receiver circuit in Figure 1 activates an audio alarm when the transmitter (Figure 2) moves beyond a specified perimeter. The transmitter functions as a voltage-controlled oscillator, operating at approximately 915 MHz within the unlicensed ISM (industrial/scientific/medical) band. It features...
FFT audio amplifier design
For all the subsequent tests, a high-quality signal generator from BlackStar was utilized. The PicoScope trace displayed below illustrates a pure 1 kHz tone from the signal generator. It is important to note that while the screenshots below depict the...
FET based audio preamplifier
This circuit is a low-noise audio preamplifier that utilizes one FET and one BJT. The audio signal to be amplified is connected to the base of FET Q1 through capacitor C1 and resistor R3. The base of transistor Q2 is...
Multi Loop Parallel Alarm Circuit
This alarm features status LEDs connected to each inverter output, which indicate the status of the corresponding sensor. S8 is utilized to monitor the switches through the LEDs or to activate an alarm using Q1 and SCR1. Additionally, BZ1 should...
Auto Alarm
SI is an external key switch. The alarm allows a delay of 0 to 45 seconds after SI is operated before the circuit is armed. During this period, LED1 lights up green. After this delay, LED1 lights red, indicating that...
Audio Dynamic Noise-Reduction System Circuit
UL is a dedicated integrated circuit (IC) from National Semiconductor that achieves up to 10 dB noise reduction through an adaptive bandwidth scheme and a psychoacoustic masking technique.
The UL integrated circuit is designed to enhance audio performance by significantly reducing...
2W audio power amplifier LM380 circuit
This document details a 2W audio power amplifier circuit that utilizes a 14-pin LM380 package as the amplification element. The input signal is managed by a volume control potentiometer (Rp) rated at 20k ohms, with a coupling capacitance of 22...
Audio Power Amplifier
Measure the voltage across the 1k resistor connected to the input stage and Vcc. The DC voltage should be approximately 2 volts, or 2 mA of current flowing through this resistor. For instance, if Vcc is at 24 volts, the...
22w stereo amplifier
This document presents a 22-watt stereo audio power amplifier circuit diagram utilizing the TDA1554 integrated circuit from NXP Semiconductors (formerly Philips Semiconductors). The circuit is designed to effectively amplify stereo signals and is characterized by its simplicity and utility. It...