Simple Sound Effect Generator Circuit Diagram Using HT2884

Here’s a design circuit for Simple Sound Effect Generator Circuit Diagram uses the Holtek HT2884 IC to produce 8 different sound effects. This is the figure of the circuit;

The HT2884 is a CMOS LSI chip equipped with tone circuit, noise circuit, and other control logic to generate various sounds to be used in sound effects production. This IC features: single power supply (2.4V – 3.3V), low stand current, auto power-off function, and eight different sound sections.

Dynamic Noise Reduction System DNR Circuit

This is a design circuit for noise reduction system. This circuit is based on LM1894. This is a simple circuit. This is the figure of the circuit;

The LM1894 is a stereo noise reduction circuit for use with audio playback systems. The DNR system is non-complementary, meaning it does not require encoded source material. The system is compatible with virtually all prerecorded tapes and FM broadcasts. Psychoacoustic masking, and an adaptive bandwidth scheme allow the DNR to achieve 10 dB of noise reduction. DNR can save circuit board space and cost because of the few additional components required.

[Circuit source: National Semiconductor Notes]

Simple Microphone Mixer Circuit

This is simple mixer was designed for three dynamic microphones, but can be re-designed for more or less. Level and tone controls are available to tailor the sound to your needs. This is the figure of the circuit;


In this circuit R1-R3 are level controls. R9 and R11 control bass and treble, respectively. Since the circuit draws such low current, two 9V batteries can be used for a power supply. This circuit is based on op amp 741 IC.

Part:
R1, R2, R3 1K 1/4W Resistor
R4, R5, R6 10K Logarithmic Pot
R7 1Meg 1/4W Resistor
R8, R10 10K 1/4W Resistor
R9, R11 100K Linear Pot
C1, C2, C5, C6 0.1uF Ceramic Disc Capacitor
C3, C4 22nF Ceramic Disc Capacitor
U1, U2 741 Op Amp
J1, J2, J3 Input Jacks Of Your Choice
MISC Board, Wire, Knobs, IC Sockets

Simple Digital Volume Control Circuit

This is volume control that cab be used for replacing your manual volume control in a stereo amplifier. This circuit is types for digital controller. This circuit is control by DS1669. Here’s the figure of the circuit.


In this circuit, push-to-on switch S1 controls the forward (volume increase) operation of both channels while a similar switch S2 controls reverse (volume decrease) operation of both channels. This circuit has low-cost alternative to mechanical control. Wide differential input voltage range between 4.5 and 8 volts. The circuit is extremely simple and compact requiring very few external components. The power supply can vary from 4.5V to 8V. Applications include volume, tone, contrast, brightness, and dimmer control.

Simple Surround Sound Decoder

This is a design for surround sound decoder. This circuit works by allowing the rear speakers to reproduce only the difference signal between the left and right outputs. This is the figure of the circuit.


Op amp U1A is connected as a subtracting amplifier. Should the same signal be applied to both inputs, the output is zero. As a result, it will remove all common information from the stereo signal, and reproduce only the difference signal - in exactly the same way as the original Hafler design. U1B is a simple summing amplifier, and the output contains all the information from both the left and right channels. A possibility that springs to mind is that we could then subtract the difference information from this output, so that only material that is absolutely common to both channels would be reproduced. Would this improve the performance to the extent that the extra circuitry is warranted? I tend to doubt it, but will look into this further.

Simple Audio Mixer Using FET

This is a simple project circuit for mixes two or more channels into one channel (eg. stereo into mono). The circuit can mix as many or as few channels as you like and consume very little power. This is the figure of the circuit.


This circuit is based on or built by FET 2N3819. The circuit can be powered by a single 9 volt battery. As many or as few channels as are required can be added to the mixer. A shielded case is probably needed to reduce hum and help stop oscillations.

Part:
R1, R3 10K Pot
R2, R4 100K 1/4 W Resistor
R5 6.8K 1/4 W Resistor
C1, C2, C3 0.1uF Capacitor
Q1 2N3819 Junction FET
MISC Wire, Shielded (Metal) Case, Phone or Other Plug For Output

Simple Delay Circuit for Surround Sound

This circuit in below uses the Mitsubishi M65830 Digital Delay chip. This has been around for a while now. This circuit is a simplest form for delaying circuit. The serial data required to obtain different delay settings is not easily obtained, and would add considerably to the complexity of the circuit. This is the figure of the circuit.


The circuit is (almost) a direct adaptation from the Mitsubishi data sheet, and as shown will give good performance over a wide frequency range. The filters are tuned to around 9.5 kHz, and although this could be reduced there does not seem to be any good reason to do so. This seems to be the optimum response for rear channel speakers, so should be left alone. The filter circuits use internal op amps, and only require the external components. The unit can be constructed as a module quite easily, requiring a 5 Volt supply, analogue and digital earth connections, and an input and output.

Simple Low Noise Audio Line Driver Circuit

This is a design for audio line driver. This circuit is based on 2 IC as controller the operation. This is a simple circuit and low noise. The LT1206 has been naturally selected as the components for video application since it has suitable bandwidth and output derive capability. This high performance features is not only suitable for video application, but also make it definitely suitable for audio application. This is the figure of the circuit.


The schematic diagram shows the LT1206 combined with the LT1115 low distortion, very low noise audio buffer with a gain of 10. With a 5VRMS and 32 Ohm load (780mW), the THD + noise for the circuit is only 0.0009% at 1 KHz, rising to 0.004% at 20 KHz. The frequency response is flat to 0.1dB from DC to 600 KHz, with a – 3dB bandwidth of 4MHz. The circuit is stable with capacitive loads of 250pF or less.
[Schematic diagram source: Linear Technology Application Notes]

Simple Audio Graphic Equalizer Circuit

This is a design circuit for audio graphic equalizers, that are very common as commercial products but circuits for them are very rarely published. This circuit is a simple design circuit. The circuit is needs an op-amp for amplifying the input signal. This is the figure of the circuit.


Only one gyrator stage is shown: all 7 gyrators are the same circuit, only the capacitors change, as shown in the chart. I have shown three of the seven faders to show where they go. A gyrator is a circuit using active devices and transistors to simulate an inductor. In this case the gyrator is the transistor acting with R1, R3 and C2. It could just as easily be a unity gain op-amp. The circuit includes three formulae: one which gives f, the the centre frequency of the band. The second shows how the Q is related to the capacitor ratio. The third shows the impedance presented by the circuit. Note that this includes 3 terms, the first purely resistive, the second is the capacitive contribution from C1 and the third is an inductive term from the gyrator.

Simple Audio Level Meter Using LM3915

This is a simple design of audio level meter. This circuit uses just one IC and a very few number of external components. This circuit is based on LM3915 as controller in the operation of the audio level meter circuit. It displays the audio level in terms of 10 LEDs. This is the figure of the circuit.


The input voltage can vary from 12V to 20V, but suggested voltage is 12V. The LM3915 is a monolithic integrated circuit that senses analog voltage levels and drives ten LEDs providing a logarithmic 3 dB/step analog display. LED current drive is regulated and programmable, eliminating the need for current limiting resistors.

The IC contains an adjustable voltage reference and an accurate ten-step voltage divider. The high-impedance input buffer accepts signals down to ground and up to within 1.5V of the positive supply. Further, it needs no protection against inputs of 35V. The input buffer drives 10 individual comparators referenced to the precision divider. Accuracy is typically better than 1 dB.

Simple Light Sensor Circuit Using Op Amp

This is a one of the light sensor. This circuit is a dark sensor that is based on op – amp 741 IC as main control. This circuit is a simple design for sensor the light at the night. This is the figure of the circuit.


For sensor the light is using LDR. Operation of the circuit is under normal conditions the resistance of the LDR is high, keeping pin 2 low. When light falls onto the LDR the resistance drops to a couple hundred ohms and triggers pin 2 high which biases the base of Q1 via pin 6 and R4 and in turn activates the relay. Trimmer pot P1 and the two 470 ohm resistors, R2 and R3, are a voltage divider to adjust for sensitivity.

If you want the action reversed (make it a dark sensor), change the positions of the LDR and R1. If the relay 'chatters', add a bit of hysteresis by adding a 100K to 1Meg-ohm resistor (R6) over pins 6 and 2 of the 741 op-amp, but in most cases 100K to 330K will do the job. The LDR is a regular, general purpose type. D1 serves as a spark-arrestor when the relay contacts open. This circuit power supply is using 12 V DC.

Simple Cascaded Timer Circuit

This is a simple design circuit that uses a CMOS dual re-trigger mono stable IC 4528 in a cascade timer circuit. The CMOS timer can be easily cascaded with other similar 4528 circuits to lengthen the timing needed. This is the figure of the circuit.


The timing of the project is determined by VR3 and C1 for the first stage and VR4 and C2 for the second stage. Once button S1 is pressed, the 1st stage output pin 6 logic level will go high and output pin 7 will go low for the preset time which is determined by VR3 and C1. When the time is up, the output pin 6 will go low and pin 7 high. At this moment of time, pin 7 will positive trigger the 2nd stage of the timer at pin 12. Output pin 10 will go high and pin 9 will go low for a time determine by VR4 and C2 before the cycle end with pin 10 back to low and pin 9 to high.

Simple 3 Band Equalizer Circuit

This is a simple design schematic for equalizer. The principle of the circuit is using a tone control. There are three ranges, basses, middle and treble in single op-amp that can be control. This is a figure of the circuit.


This circuit is using a single op-amp this easy to make equalizer offers three ranges, low frequency, mid frequency, and high frequency. The op-amp is based on LF351 IC with component values shown there is approximately +/-20dB of boost or cut at frequencies of 50Hz, 1kHz and 10kHz. Supply voltage may be anything from 6 to 30 Volts. Maximum boost 20dB is only realized with maximum supply voltage of 18 Volt.

Simple Speaker Microphone Circuit

This circuit allows you to use a cheap and a simple loudspeaker as a microphone. This circuit is based on a transistor BC109C. Sound waves reaching the speaker cone cause fluctuations in the voice coil. The voice coil moving in the speaker magnetic field will produce a small electrical signal. The circuit is designed to be used with an operating voltage between 6 and 12 volts dc. This is the picture of the circuit;


How is this circuit work? The first transistor operates in common base mode. This has the advantage of matching the low input impedance of the speaker to the common base stage, and secondly has a high voltage gain. The second stage is direct coupled and operates in emitter follower. Voltage gain is slightly less than unity, but output impedance is low, and will drive long cables.

Speech quality is not as good compared to an ordinary or ECM microphone, but quite acceptable results can be obtained. Speaker cones with diameters of 1 inch to 3 inches may be used. Speaker impedance may be 4 ohm to 64 ohm. The 8.2 ohm resistor value may be changed to match the actual speakers own impedance.

A Simple Crossover Circuit for Tweeter

A single coil speaker is not good in handling high and low frequency at the same time. If we could filter out the low frequency and play it through a tweeter, it will produce more sound quality than using a single speaker. In this figure shows the answer for the problem in above. This is a simple design circuit for protected thee voltage and current in tweeter speaker.


The concept of operation this circuit is the speaker that can protected is tweeter with 4 or 8 ohm impedance. R1 is a potentiometer resistor that used to adjust matching the tweeter speaker output level to that of woofer. R1 should be rated more than 2 Watts.

A Simple 3 Band Equalizer

This is a simple 3 band graphic equalizer circuit that’s built by a single op amp IC LF351 IC and few passive components. The component values of this circuit are not very critical and can be replaced with nearest values with a little loss on the performance. This is feature make it easy to be assembled from your junk box. This is a figure of the circuit;


How is the simple 3 band graphic equalizer work? The op amp LF351 is wired to operate in three frequency ranges-high, medium and low. The circuit is designed such that the circuit produces +/-20 dB boost or attenuation for 50Hz,1KHz and 10Khz by varying POT’s R3, R6 and R9.The maximum amplification for any of these bands at maximum supply voltage is 20dB.The op amp LF 351 is wired as an inverting amplifier whose response to frequencies 50Hz,1Khz and 10KHz can be varied by adjusting POT’s R3,R6 and R9.