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This is a generator circuit which is very useful, it simultaneously generates two types of noise, pink and white. The noise generator is a circuit that produces electrical noise . Noise generators are used to test , measure noise , frequency response , and other parameters . The circuit described here is based on the operational amplifier 741 .  Dual White Noise and Pink Noise Generator Circuit Diagram

This circuit is intended to signal, through a flashing LED, the exceeding of a fixed threshold in room noise, chosen from three fixed levels, namely 50, 70 & 85 dB. Two Op-amps provide the necessary circuit gain for sounds picked-up by a miniature electret microphone to drive a LED. With SW1 in the first position the circuit is off. Second, third and fourth positions power the circuit and set the input sensitivity threshold to 85, 70 & 50 dB respectively. Current drawing is 1mA with LED off and 12-15mA when the LED is steady on. Circuit diagram : Room Noise Detector Circuit diagram Parts List : R1____________10K 1/4W Resistor R2,R3_________22K 1/4W Resistors R4___________100K 1/4W Resistor R5,R9,R10_____56K 1/4W Resistors R6_____________5K6 1/4W Resistor R7___________560R 1/4W Resistor R8_____________2K2 1/4W Resistor R11____________1K 1/4W Resistor R12___________33K 1/4W Resistor R13__________330R 1/4W Resistor C1___________100nF 63V Polyester Capacitor C2____________10µF 25V ...

This Room Noise Detector Schematic circuit diagram is intended to signal, through a flashing LED, the exceeding of a fixed threshold in room noise, chosen from three fixed levels, namely 50, 70 & 85 dB. Two Op-amps provide the necessary circuit gain for sounds picked-up by a miniature electret microphone to drive a LED. With SW1 in the first position the circuit is off. Second, third and fourth positions power the circuit and set the input sensitivity threshold to 85, 70 & 50 dB respectively. Current drawing is 1mA with LED off and 12-15mA when the LED is steady on. Circuit diagram : Room Noise Detector Circuit diagram   Parts List : R1____________10K 1/4W Resistor R2,R3_________22K 1/4W Resistors R4___________100K 1/4W Resistor R5,R9,R1 _____56K 1/4W Resistors R6_____________5K6 1/4W Resistor R7___________560R 1/4W Resistor R8_____________2K2 1/4W Resistor R11____________1K 1/4W Resistor R12___________33K 1/4W Resistor R13__________330R 1/4W Resistor C1_____...

Description Regarding this circuit has three change-able notch filters configurations are display . You can take to used in your small pre-amp or amplifier circuit to filter out any HUM for 50 Hz ( European ) or 60Hz . With sustituting the capacitors values in the bridge other frequencies can be apply. About all IC op-amps configuration requires a +/- voltage supply which can easily provided with a voltage divider made of 2 each 100K resistors and a 10 uF filtering capacitor connected from ground to the negative rail . Any op-amps such as the LF353 , TL071, LM308 , They can be used and supply from 9 volt battery or other voltage up to 30 volts can be used  Source -http://www.free-circuit.com/2011/02/11/60hz-noise-fillers-adjustable-circuit-and-pcb-parts-assembly/

This circuit is intended to signal, through a flashing LED, the exceeding of a fixed threshold in room noise, chosen from three fixed levels, namely 50, 70 & 85 dB. Two Op-amps provide the necessary circuit gain for sounds picked-up by a miniature electret microphone to drive a LED. With SW1 in the first position the circuit is off. Second, third and fourth positions power the circuit and set the input sensitivity threshold to 85, 70 & 50 dB respectively. Current drawing is 1mA with LED off and 12-15mA when the LED is steady on. Bed Room Noise Detector Circuit Schematic  Room Noise Detector Circuit Diagram Parts: R1 = 10K R2 = 22K R3 = 22K R4 = 100K R5 = 56K R6 = 5.6K R7 = 560R R8 = 2.2K R9 = 56K R10 = 56K R11 = 1K R12 = 33K R13 = 330R C1 = 100nF-63V C2 = 10µF-25V C3 = 470µF-25V C4 = 47µF-25V D1 = 5mm. Red LED Q1 = BC327 B1 = 9V PP3 Battery SW1 = 2 poles 4 ways rotary switch IC1 = LM358 Low Power Dual Op-amp MIC1 = Miniature electret microphone Use: Place the small box cont...

Receiver interference is hardly an unknown problem among model builders. Preventive measures in the form of ferrite beads fitted to servo cables are often seen in relatively large models and/or electrically driven models, to prevent the cables from acting as antennas and radiating interference to the receiver. If miniature ferrite beads are used for this purpose, the connector must be first be taken apart, after which the lead must be threaded through the bead (perhaps making several turns around the core) and then soldered back onto the connector. An interference source can also cause problems in the receiver via the power supply connection.  The battery is normally connected directly to the receiver, with the servos in turn being powered from the receiver. The servos can draw high currents when they operate, which means they can create a lot of noise on the supply line. This sort of interference can be kept under control by isolating the supply voltage for the receiver from the s...

LOW NOISE WHITE LED DRIVER SYSTEM ELECTRONIC DIAGRAM The LM3570 evaluation board has a chip enable pin (active high logic) as well as a PWM (active high logic) pin which allows current sources to be turned on and off without completely disabling the part..The LM3570 is capable of supplying up to 80mA of current split between the regulated current sources and VOUT. The LM3570 comes in National’s LLP-14 package.