Single Chip Theremin Circuit

 This schematic diagram show a single chip Theremin circuit.  Theremin is an electronic music instrument which sense hand movement to control the tones/frequency. This Theremin circuit uses two separate Colpitts LC oscillators to produce a beat frequency. The frequencies of  two Colpitts LC oscillators are mixed and then rectified.

Compact 3W BTL Audio Power Amplifier Schematic TDA7056

 Bridge-tied-load (BTL) configuration in an amplifier is basically a H-network  with the loud-speaker as the “bridge” between two active valve or switcher. This configuration allow a full alternating current signal to be produced at the load (loudspeaker) without a transformer or a symmetric power supply. Here are some benefits of BTL configuration:

Simple Guitar Amplifier

This is a design for a circuit for a small 386-based amplifier called the Ruby which is very well suited to our needs here. That’s worked great with hot pickups but did not have enough gain for lower-output pickups. Fortunately, they also have a preamp design called the Fetzer valve which is enough of a preamp to get sustain with about any pickup I've tried. 

Subwoofer Filter Circuit

If the audio device has a bass tone quality that is less kicking, to overcome this problem is to add an active subwoofer / crossover filter so that the tone other than the low frequency will not be passed to the power amplifier and the sound coming out of the speaker will appear even more. This the figure of the schematic diagram.

Tips for Increasing Bass Sound for Car System Sounds

To improve the quality of the car's sound system is to replace standard audio devices. The speaker is the audio device that is most often replaced, the reason for the user is because the sound quality standard speakers are not maximal. In addition to the poor sound quality, if the music volume is loud the speaker sound is not strong enough. 

Let's look at this article how the Power Amplifier & Subwoofer makes the power more maximal The second reason is because replacing speakers is more practical and installation is faster. The market can easily be bought at a fairly affordable price. But do not just buy speakers if you do not understand the specifications of the speaker, not even better, the results of the sound that is not in line with expectations. 

Car Audio Power Bridging Terms

Not only getting married is there a condition, bridging also has conditions. Because if you do not comply with these conditions then your power can be broken down in just a few hours or just a few songs with no maximum. Then what are the conditions? These conditions have been written by the manufacturer, so you should read the manual that indicates the condition if the power is in the cartridge. 

Then what are the conditions? These conditions have been written by the manufacturer, so you should read the manual that indicates the condition if the power is in the cartridge. In refilling the car audio power, we should not arbitrarily connect the cable, it must be right between the pluses and minuses - that's the first condition.

Bridging Car Audio Power

The method used in creating bridge audio power in a car.

a. stereo 2 channel bridge into 1 mono channel.The first method of car power audio bridging is combining 2 channel stereo output into 1 mono output to push 1 subwoofer speaker - this is called mono bridging. This means that under normal conditions a 2 channel power is for 2 4Ω speakers. Now, after a mono power cartridge is only to push a speaker, with impedance 2Ω; this of course the power of (rms) power will double. 

Note that the fewer speaker barriers, the power amp rms will increase as well; but with a note that this is also supported by the power amplifier. For example: A 2 channel stereo power amplifier has an output specification of 2x100watt @ 4Ω, bridge mode 1x400w @ 2Ω. This means that if the power is mono cartridge, we can use double coil speakers set to 2Ω, with output power to the speaker by 400 watts. Do you have to play at 2Ω only? The answer depends on the power, if you have stability playing at 1Ω or 4Ω there will certainly be no problem. 

1uS Light Pulse Receiver Circuit With Post Amp

Here’s a design circuit for light pulse receiver circuit that is used to detect very weak light pulses lasting 1uS. In the figure at below is a figure to show the schematic diagram circuit;

This circuit uses a tuned LC feedback network to provide high sensitivity while giving high ambient light immunity. A post voltage amplifier is included with a gain of about X20. The circuit is described in more detail in the receiver section of my Handbook of Optical Through the Air Communications.  Note: The LF357 op amp is no longer available, this circuit is for reference only.

DC-Coupled Audio Amplifier Circuit

This is a design circuit of audio amplifiers with DC coupling to the load are not often encountered these days, even though they offer definite advantages. One advantage is that there is no need for the complication of a second (symmetric) power supply; another is good frequency and phase response. Also, no special electrolytic capacitors are needed for voltage stabilization, and switch-on ‘thump’ is much reduced. This is the figure of the circuit;

It consists of a voltage divider, a voltage follower and the loudspeaker in the headphones, whose other side is connected to the junction of two electrolytic capacitors, providing the virtual earth. The potential at this point is, of course, half the supply voltage. All we need to do now is suitably couple in the audio signal to be amplified. This figure shows a practical realization of this idea in the form of a stereo headphone amplifier. The amplifier itself consists of IC1 and P1, R3 and R4 (giving a gain of 11). This part of the circuit demands no further explanation, and the same goes for the voltage divider mentioned above, formed by R1a and R1b. The signal is coupled in via the potentiometers. C2 and R2 have a special purpose: C2 connects the bottom end of the potentiometers (ground for the input signal) to the virtual earth. However, this capacitor creates a feedback path which can lead to oscillation of the amplifier under some circumstances. R2 damps this tendency to oscillate. It is possible to calculate suitable values for these components, but it is better to determine them by experiment. C2 must be sufficiently large that stray electric fields do not cause unacceptable hum at the output. R2 must be sufficiently large that the voltage at the amplifier’s virtual earth stabilizes quickly enough after switch-on. The polarity of the electrolytic is unimportant as no significant voltage appears across the network. It is possible to try the circuit out with the C2/R2 network shorted and observe the behavior of the circuit at switch-on using an oscilloscope. Depending on the degree of asymmetry in the circuit, the voltage at the virtual earth point can take a considerable time to stabilize.

High CMR Isolation Amplifier Circuit

transients that are generated by the switching of the inverter transistors. Here’s the figure of the design circuit;

Developed as a compact low-cost solution for just this type of design problem, the HCPL-7800 High CMR Isolation Amplifier allows designers to sense current in extremely noisy environments while maintaining excellent gain and off set accuracy. It exhibits outstanding stability over both time and temperature, as well as unequaled common-mode transient noise rejection (CMR). To achieve such a high level of performance, the HCPL) analog-to-digital converter (-7800 combines several different technologies, including a state-of-the-art sigma-delta (ADCm standard-cell), chopper-stabilized internal amplifiers, a fully differential circuit topology fabricated on a 1  CMOS process, an edge-triggered level-sensitive data encoder/decoder circuit, a high-efficiency, high-speed AlGaAs LED, an advanced photo-detector noise shield, and an efficient “light-pipe” packaging technology. The HCPL-7800 is available in a small 8-pin DIP package, making it the world’s smallest isolation amplifier.

7 Watt Class B Audio Amplifier Circuit

This is a design circuit for amplifier was designed in order to fill the gap in the 3-10 Watts power output range of the audio amplifiers available on RED Free Circuit Designs. Therefore a simple, very low parts-count amplifier, was designed on the same guidelines of the successful 45 Watt Class B Amplifier, but using the excellent NE5534 IC instead of a discrete component op-amp to drive the output "dumper" transistors. This is the figure of the circuit;

Due to the maximum operating voltage restrictions of the chip, the output power cannot exceed 7.5 Watts into 8 Ohm loads, but the Total Harmonic Distortion figures are astonishingly low, much lower than comparable audio amplifiers using a single IC audio amp. Also due to the internal current limiting of the NE5534, the output power into 4 Ohm loads will be no more than 8 Watts. Other interesting features of this amplifier are the absence of any kind of setup and the possibility to be driven directly by the audio source (CD player, Tuner, iPod etc.).

In any case, a simple, optional preamplifier circuit is provided, allowing to cope with very low output audio sources and featuring a single-knob bass and treble Tone Control.

TDA7056 3W BTL Mono Audio Power Amplifier Circuit

Here’s a design circuit for mono output amplifier application,  TDA7056  IC can be your option. Compact but powerful, this integrated circuit is contained in a 9 pin medium power package. This device is designed for battery fed portable equipments such as mono recorders, radios and television. This is the figure of the circuit;

To attract the market, TDA7056 has many features such as low power consumption. For more reliable operation, TDA7056 also has short circuit proof and ESD (Electro Static Discharge) protected on all pins.  Designing application with this IC should be easy since no external components is needed. To make sure you’ll love this chip, this device also has no switch on/off clicks. Overall, TDA7056 has good stability. [Circuit schematic diagram source: Philips Semiconductors Datasheet]

MAX2664/MAX2665 VHF UHF Low Noise Amplifiers Circuit

Here’s a design circuit for very simple low cost and ultra compact VHF UHF Low-Noise amplifiers circuit can be designed using the MAX2664 and MAX2665 ultra-compact LNAs for VHF/UHF applications. These devices incorporate a broadband LNA with an integrated bypass switch. The MAX2664 covers the UHF frequency range from 470MHz to 860MHz, and the MAX2665 covers the VHF frequency range from 75MHz to 230MHz. Each device has a zero-power bypass mode for improved high-signal-level handling conditions. This is the figure of the circuit;

As you can see in the presented circuit diagram, this RF project requires very few external components . Both ICs has a high gain around 15dB and require a single power supply, that can provide an output voltage between 2.4 to 3.5 volts. VHF UHF Low-Noise amplifiers has a very low current consumption of 3.3 mA and can be used in applications like: Smart phones/Handsets , MP3 Players , Home Audio/Video and other portable navigation devices.

Video Distributor Amplifier Circuit

This circuit is design for useful to amplify and distribute video signals with low noise and without losses. The CA3100 is a fast op amp designed to amplify video signals. Set the P1 to control the input signal level to have a clear picture on the TV set. This is the figure of the circuit;

Basic Unity Gain Buffer Circuit

This is a circuit for basic unity gain buffer circuit. The circuit gives the highest input impedance of any operational amplifier circuit. Input impedance is equal to the differential input impedance multiplied by the open-loop gain, in parallel with common mode input impedance. Here’s the figure of the circuit;

 

The gain error of this circuit is equal to the reciprocal of the amplifier open-loop gain or to the common mode rejection, whichever is less. Input impedance is a misleading concept in a DC coupled unity-gain buffer. Bias current for the amplifier will be supplied by the source resistance and will cause an error at the amplifier input due to its voltage drop across the source resistance. Since this is the case, a low bias current amplifier such as the LH1026 should be chosen as a unity-gain buffer when working from high source resistances.

VOUT = VIN
R1 = RSOURCE
 

The cautions to be observed in applying this circuit are three, the amplifier must be compensated for unity gain operation, the output swing of the amplifier may be limited by the amplifier common mode range, and some amplifiers exhibit a latchup mode when the amplifier common mode range is exceeded. The LM107 may be used in this circuit with none of these problems or, for faster operation, the LM102 may be chosen. [Circuit diagram source: National Semiconductor Application Notes]

Wide Voltage Range 1.8 Watt Audio Power Amplifier with Short Circuit Protection

This is a design circuit for audio power amplifier using protection circuit. This circuit is based on LM4951A.  This is the figure of the circuit;

The LM4951A is an audio power amplifier designed for applications with supply voltages ranging from 2.7V up to 9V. The LM4951A is capable of delivering 1.8W continuous average power with less than 1% THD+N into a bridge connected 8Ω load when operating from a 7.5VDC power supply. Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components. The LM4951A does not require bootstrap capacitors, or snubber circuits. 

The LM4951A features a low-power consumption active-low shutdown mode. Additionally, the LM4951A features an internal thermal shutdown protection mechanism and short circuit protection. The LM4951A contains advanced pop & click circuitry that eliminates noises which would otherwise occur during turn-on and turn-off transitions. The LM4951A is unity-gain stable and can be configured by external gain-setting resistors.

[Circuit schematic source: National Semiconductor Notes] 

10 Watt Stereo Amplifier Circuit Using TDA2009A

This is a design circuit for amplifier. This amplifier circuit has a power of 10 watts. This amplifier circuit is very suitable to apply to your car audio. This amplifier is using IC TDA2009A, as amplifier power. To avoid excessive heat in the IC using some heat sink compound between the heat sink & the IC. C1 & C2 is the input coupling capacitor and blocks DC, as well as C10 & C11 which is the output capacitor Kopel, and C6 & C7 which blocks the DC from the feedback loop. R1/R2 (and R3/R4) set the level of feedback. This is the figure of the circuit.

Get together with 1 (R1/R2) = 68 or 37 dB. C8/R5 (and C9/R6) provides high frequency stability where loudspeaker inductive reactance load can become excessive. C4 and C5 provide power decoupling or filtering. Absolute maximum supply voltage is 28V for the amplifier.

Single Supply Instrumentation Amplifier Circuit

This is a design circuit for a single supply instrumentation amplifier circuit. This circuit can be used to replace the function of conventional differential-amplifier topologies to load the DC gain on a low level signal. This circuit has high input impedance of non-inverting op-amp inputs. This is the figure of the circuit; 

 

This circuit uses single supply, so the strain gauges are operated from Vcc. There is a disadvantage of this circuit a matched resistor is needed to build this circuit. That will suffer from poor CMRR. The circuit shown above can be modified by eliminating three resistors and by using only two op-amps. This is the figure of the modified circuit;

 

 

Two circuits above has some advantages and disadvantages. The disadvantages for first modified circuit are the two resistors must be changed instead of one and must be matched resistor. Besides that, the first stage cannot be used for gain. However, it will easy to calculate the gain of the circuit. The second modified circuit is not recommended because it may be unstable due to the operating of first op amp at less than unity gain. Besides that the propagation delay of the signal from Vin- is more than Vin+.
[Schematic circuit source: Texas Instruments Application Note]

High Fidelity Stereo Power Amplifier Circuit

This is a design circuit for audio power amplifier design utilizing the LM4702. This is a complete circuit for power amplifier design. This circuit has high quality circuit board layouts, the LM4702 power amplifier driver requires careful consideration. A good place to start is with the ground and power circuits design layout. This is the figure of the circuit;

Star connections for ground and power are always a good practice for audio circuit board layouts. A star connection is where there are individual traces from each component in the circuit that return to a central point. Notice how all the ground traces converge at the left side of the board, near Rs1 and Rs2, and connect to the two ground pins in the center of the power connector. The ground traces that connect to the right and left output jacks also converge at the center of the star ground which is the center of the power connector where the two ground pins are located.

[Circuit source: National Semiconductor Notes]

10 Watt Stereo Amplifier Circuit Using TDA2009A

This is a design circuit for amplifier. This amplifier circuit has a power of 10 watts. This amplifier circuit is very suitable to apply to your car audio. This amplifier is using IC TDA2009A, as amplifier power. To avoid excessive heat in the IC using some heat sink compound between the heat sink & the IC. C1 & C2 is the input coupling capacitor and blocks DC, as well as C10 & C11 which is the output capacitor Kopel, and C6 & C7 which blocks the DC from the feedback loop. R1/R2 (and R3/R4) set the level of feedback. This is the figure of the circuit.

Get together with 1 (R1/R2) = 68 or 37 dB. C8/R5 (and C9/R6) provides high frequency stability where loudspeaker inductive reactance load can become excessive. C4 and C5 provide power decoupling or filtering. Absolute maximum supply voltage is 28V for the amplifier.