Simple Computer Audio Booster Circuit Diagram

This is a simple amplifier for boosting the audio level from low-power sound cards or other audio sources driving small speakers like toys or small transistor radios. The circuit will deliver about 2 watts as shown. The parts are not critical and substitutions will usually work. 

Simple Computer Audio Booster Circuit Diagram

 

 The two 2.2 ohm resistors may be replaced with one 3.9 ohm resistor in either emitter.

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Input Impedance Booster Circuit Diagram

The input resistance of a.c.-coupled op amp circuits depends almost entirely on the resistance with which the d.c. setting is determined. If CMOS op amps are used, the input resistance is normally high, currently up to 10 MΩ. If a higher value is needed, a bootstrap circuit may be used. This enables the input resistance to be boosted artificially to a very high value, indeed In the circuit shown in the diagram, resistor R1 sets the d.c. point for IC1a. The terminal of the resistor linked to pin 7 of IC1 would normally be at earth potential, so that the input impedance would be 10 MΩ. Connecting the other terminal of the resistor to earth via IC1a and network C2-R3-R2 as far as d.c. is concerned results in the requisite d.c. setting of the op amp.

Circuit diagram:

Input Impedance Booster II Circuit Diagram

As far as alternating voltages are concerned, the input signal is fed back so that only a tiny alternating current flows through R1. Therefore, Rin=R1[(R2+R3)/R3]. With resistor values as specified, Rin is about 1 GΩ. One aspect must be borne in mind: the numerical value of (R2+R3)/R3 must not exceed 0.99. This means that the value of R3 cannot be less than 100 kΩ if the value of R2 is 10 MΩ. If these conditions are not met, the circuit will become unstable.

Copyright: Elektor Electronics

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USB Power Booster Circuits Diagram

The USB serial bus can be configured for connecting several peripheral devices to a single PC. It is more complex than RS232, but faster and simpler for PC expansion.Since a PC can supply only a limited power to the external devices connected through its USB port, when too many devices are connected simultaneously, there is a possibility of power shortage. Therefore an external power source has to be added to power the external devices.

Circuit diagram:

USB Power Booster Circuit Diagram

In USB, two different types of connectors are used: type A and type  B. The circuit presented here is an add-on unit, designed to add more power to a USB supply line (type-A). When power signal from the PC (+5V) is received through socket A, LED1 glows, opto-diac IC1 conducts and TRIAC1 is triggered, resulting in availability of mains supply from the primary of transformer X1. Now transformer X1 delivers 12V at its secondary, which is rectified by a bridge rectifier comprising diodes D1 through D4 and filtered by capacitor C2.

 Pin configurations of moc3021, bt136 and 5v regulator 7805

Regulator 7805 is used to stabilise the rectified DC. Capacitor C3 at the output of the regulator bypasses the ripples present in the rectified DC output. LED1 indicates the status of the USB power booster circuit. Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. Bring out the +5V, ground and data points in the type-A socket. Connect the data cables as assigned in the circuit and the USB power booster is ready to function.

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Ampere or Current Booster

Volt regulators such as the LM708, and LM317 series (and others) sometimes need to provide a little bit more current then they actually can handle. If that is the case, this little circuit can help out. A power transistor such as the 2N3772 or similar can be used.

The power transistor is used to boost the extra needed current above the maximum allowable current provided via the regulator.


Current up to 1500mA(1.5amp) will flow through the regulator, anything above that makes the regulator conduct and adding the extra needed current to the output load. It is no problem stacking power transistors for even more current. (see diagram). Both regulator and power transistor must be mounted on an adequate heatsink.

Circuit diagram:

Ampere or Current Booster Circuit Diagram

Parts:

R1 = 1R-2W
R2 = 10R-2W
C1 = 35v-470uF
C2 = 35v-470uF
Q1 = TIP2955
IC1 = 78xx Regulator

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Low-Power Voltage Doubler Circuit Diagram

All miniature electronic devices operate off batteries. Some of them need higher than the standard battery voltages to operate efficiently. If the battery of that specific voltage is unavailable, we are forced to connect additional cells in series to step up the DC voltage. Thus, the true meaning of miniaturisation is lost. A simple way to overcome this problem is to employ a voltage doubler, if the device under consideration can operate at a small current.

Here we present a low-power voltage doubler circuit that can be readily used with devices that demand higher voltage than that of a standard battery but low operating current to work with. The circuit is quite simple as it uses only a few components. Yet, the output efficiency is 75 to 85 percent along its operating voltage range. The available battery voltage is almost doubled at the output of the circuit.

Here IC1 is wired as an astable multivibrator to generate rectangular pulses at around 10 kHz. This frequency and duty cycle of the pulses can be varied using preset VR1. The pulses are applied to switching transistors T1 and T2 for driving the output section, which is configured as a voltage-doubling circuit. The doubled voltage is available across capacitor C5. During each cycle of the pulse occurance, the high level drives T1 into its saturation, keeping transistor T2 cut off.

Circuit diagram:

Low-Power Voltage Doubler Circuit Diagram

So transistor T1 charges capacitor C4 via the path formed by diodes D2 and D1 to a voltage level slightly lesser than the supply. But during the low period of the pulse, transistor T1 is cut off while transistor T2 is driven into saturation. Now, transistor T2 raises the charge on the negative pole of capacitor C4 by another step equal to the supply voltage. Therefore an equal amount of charging is built up on capacitor C5 via diode D3.

This doubling action increases the total voltage across capacitor C5 to almost double the input voltage. If the output of the pulse generator is maintained with a high enough amplitude and frequency, the output voltage and current remain constant and cater to the needs of the load. Even with the half-wave function, this circuit is almost free of ripple voltage. If the connected load doesn’t require a high current, the efficiency can be expected in the upper 90 percentranges.

Since the input voltage is doubled, the current drain from the input power supply is also doubled at the input but halved at the output. One point of caution is that if the multivibrator’s frequency is fairly high, the output may suffer with the interference imposed over the DC voltage. In this case, the frequency must be set favorably by trials and actual load connection procedure. This tiny circuit can be assembled on the general-purpose PCB. If all of the components are surface-mount type, the whole module can be genuinely miniaturized.

EFY Lab note. During testing with input of 8V and 1.25mA load current the output voltage was found to be around 13V.

Author :M.K. Chandra ,Mouleeswaran And A.N. Vadivudai Naayaki

Source: www . efymag . com

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Audio Booster Circuit Diagram

The amplifier's gain is nominally 20 dB. Its frequency response is determined primarily by the value of just a few components-primarily C1 and R1. The values of the schematic diagram provide a response of ±3.0 dB from about 120 Hz to better than 20,000 Hz.Actually, the frequency response is ruler flat from about 170 Hz to well over 20,000 Hz; it's the low end that deviates from a flat frequency response. 

The low end's roll-off is primarily a function of capacitor C1(since RI's resistive value is fixed). If C1's value is changed to 0.1 pF, the low end's comer frequency-the frequency at which the low-end roll-off starts-is reduced to about 70 Hz. If you need an even deeper low-end roll-off, change C1 to a 1.0 pF capacitor; if it's an electrolytic type, make certain that it's installed into the circuit with the correct polarity, with the positive terminal connected to Q1's base terminal.

Circuit Diagram:

 Audio Booster Circuit Diagram

Parts	Description
P1	100K
R1	47K
R2	470K
R3	10K
R4	560R
R5	270R
C1	0.1uF-25v
C2	3.3uF-25v
C3	470uF-25V
D1	5mm. Red Led
B1	9v Battery
J1	RCA Audio Input Socket
J2	RCA Audio Output Socket
S1	On-Off Switch

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Bass Booster Circuit Diagram

This Bass Boost is today's sound... whether it's the driving, gut-vibration pulsation of disco, or the solid bass line of soft, hard, or laid-back rock. One way to get the modern bass-boost sound without running out and buying an all-new expensive piece of equipment is to use a Bass Booster between your guitar, electronic organ or what-have-you, and the instrument amplifier. 

A bass booster strips the highs from the instrument's output signal and amplifies low frequencies, feeding on "all-bass" sound to the instrument amplifier. Naturally, the bigger the speaker used with the amp, the more powerful the bass: use 15-inchers with the Bass Booster and you can rattle the windows. Bass Booster is powered by an ordinary 9 volt transistor radio battery. It can be assembled on a small printed board or on a veroboard using point to point wiring. The booster connects between your instrument and its amplifier through two standard RCA Jacks.

Circuit Diagram:

 Bass Booster Circuit Diagram

Parts:
P1 = 50K
P2 = 100K
R1 = 22K
R2 = 470K
R3 = 47K
R4 = 10K
R5 = 470R
R6 = 1K
Q1 = 2N2222
C1 = 2.2uF-25v
C2 = 100nF-63v
C31 = 00nF-63V
C4 = 3.3uF-25v
C5 = 470uF-25v
D1 = 5mm. Red Led
Q1 = 2N2222
B1 = 9v Battery
J1 = RCA Audio Input Socket
J2 = RCA Audio Output Socket
S1 = On-Off Switch

Using Bass Booster:

Connect your electronic guitar or other electronic instrument to input jack J1; Connect output jack J2 to your instruments amplifier's normally-used input. With power switch S1 off, key S2 so the instrument feeds directly to the instrument amplifier. With P2 set full counter-clockwise (Off), turn power switch S1 on, key S2 once, and advance P2 for the desired Bass Boost level. To cut back to natural sound just stomp down on S2 and key the Bass Booster out. Don't worry about leaving power switch S1 on for several hours of a gig. The circuit pulls less than 1mA from the battery, so battery will last many, many months.

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Step-Up Booster Powers Eight White LEDs

Tiny white LEDs are capable of delivering ample white light without the fragility problems and costs associated with fluorescent backlights. They do pose a problem however in that their forward voltage can be as high as 4 V, precluding them being from powered directly from a single Li-Ion cell. Applications requiring more white LEDs or higher efficiency can use an LT1615 boost converter to drive a series connected array of LEDs. The high efficiency circuit (about 80%) shown here can provide a constant-current drive for up to eight LEDs. Driving eight white LEDs in series requires at least 29 V at the output and this is possible thanks to the internal 36-V, 350-mA switch in the LT1615.

The constant-current design of the circuit guarantees a steady current through all LEDs, regardless of the forward voltage differences between them. Although this circuit was designed to operate from a single Li-Ion battery (2.5V to 4.5V), the LT1615 is also capable of operating from inputs as low as 1 V with relevant output power reductions. The Motorola MBR0520 surface mount Schottky diode (0.5 A 20 V) is a good choice for D1 if the output voltage does not exceed 20 V. In this application however, it is better to use a diode that can withstand higher voltages like the MBR0540 (0.5 A, 40 V). Schottky diodes, with their low forward voltage drop and fast switching speed, are the best match.

Many different manufacturers make equivalent parts, but make sure that the component is rated to handle at least 0.35 A. Inductor L1, a 4.7-µH choke, is available from Murata, Sumida, Coilcraft, etc. In order to maintain the constant off-time (0.4 ms) control scheme of the LT1615, the on-chip power switch is turned off only after the 350-mA (or 100-mA for the LT1615-1) current limit is reached. There is a 100-ns delay between the time when the current limit is reached and when the switch actually turns off. During this delay, the inductor current exceeds the current limit by a small amount. This current overshoot can be beneficial as it helps increase the amount of available output current for smaller inductor values.

This will be the peak current passed by the inductor (and the diode) during normal operation. Although it is internally current-limited to 350 mA, the power switch of the LT1615 can handle larger currents without problems, but the overall efficiency will suffer. Best results will be o btained when IPEAK is kept well below 700 mA for the LT1615.The LT1615 uses a constant off-time control scheme to provide high efficiencies over a wide range of output current. The LT1615 also contains circuitry to provide protection during start-up and under short-circuit conditions.

When the FB pin voltage is at less than approximately 600 mV, the switch off-time is increased to 1.5 ms and the current limit is reduced to around 250 mA (i.e., 70% of its normal value). This reduces the average inductor current and helps minimize the power dissipation in the LT1615 power switch and in the external inductor L1 and diode D1. The output current is determined by Vref/R1, in this case, 1.23V/68 = 18 mA). Further information on the LT1615 may be found in the device datasheets which may be downloaded from www.linear-tech.com/pdf/16151fa.pdf

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Hydrophone Booster Amplifier (HA2) Circuit Diagram

The HP series Hydrophone Booster Amplifier (HA2) amplifies low-level hydrophone signals over a wide range of frequencies. It has a minimum gain of 25dB and an input and output impedance of 50Ω. The HA2 is designed for use with either Precision Acoustics membrane hydrophone or Precision Acoustics HP Series Hydrophone Measurement System, which is shown in Fig 1.

Hydrophone Booster Amplifier (HA2) Circuit Diagram

Alternatively, the HA2 may be used when the acoustic signal is provided by a high output impedance hydrophone, such as a GEC-Marconi membrane device, or a conventional hydrophone. In this instance a BNC/MCX adaptor is used which connects directly to the HP Series Submersible Preamplifier, using it as a buffer amplifier, (i.e. the standard Precision Acoustic HP Series configuration shown in Fig 1 is used, but without the interchangeable probe).

The HA2 amplifier is straightforward to use but the following points should be noted:

• The output of the amplifier should be correctly terminated in 50Ω before operation.
• The HA2 amplifier is non-inverting but this is of no consequence when used with the HP Series interchangeable probes as their design takes this into account. However when a submersible preamplifier is used as a high impedance buffer amplifier (as in Fig 2) the system output from the HA2 will be inverted as the HP Series Submersible Preamplifier is inverting.

Before Connecting the unit please read WARNING

To Connect

To  Disconnect

1	Connect Output Load	1	Remove RF Input
2	Apply DC Voltage	2	Remove DC Volts
3	Apply RF Input	3	Remove Load

Specification (HA2 Amplifier Only)

Voltage Gain = 25dB minimum
Bandwidth =  50kHz to 125MHz ±1.0dB
Maximum Output Level = 29dBm for 1dB compression (18.1V pk – pk into 50Ω load)
Input Impedance = Nominal 50Ω
Output Impedance  Nominal 50Ω (VSWR 2:1)
Output Noise Level = Typically 70μV pk – pk (bandwidth 125MHz)
Noise Figure = Typically 10dB
Phase = Non-inverting
Terminations:
Front panel = Input BNC socket BNC Output socket
Rear panel Power Requirements = 28v dc output to supply DC Coupler 100/120/220/240V ac, 50 to 60Hz,
7.5W
Operating Temperature = 0 to 50°C
Size = (90mm × 205mm ×194mm)
Weight = 2.6kg

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Mp3 Booster Circuit Diagram

MP3 players are all the rage these days. The smaller ones in memory-stick format are particularly easy to take with you; your very own ‘personal sound system’ on the move! It’s when you want others to share your taste in music that you find these players to have a lack of power. You can get round this problem with the help of the MP3 booster, a small amplifier that can be used to connect your MP3 player directly to your Hi-Fi. When you next invite your friends to a party you can ask them to bring their ‘personal music’ as well as the usual drinks!

But first we have to build this booster! The small battery-powered players have an output signal that is more than sufficient to drive a set of 32 Ohm headphones. You’ll often find that with an output of 1mW the sound pressure level (SPL) produced can reach up to 90 dB. This would be sufficient to cause permanent damage to your hearing after only one hour! The maximum output voltage will then be around 200mV. This, however, is insufficient to fully drive a power amplifier. For this you’ll need an extra circuit that boosts the output voltage.

Power amps usually require 1 V for maximum output, hence the signal has to be amplified by a factor of five. We will also have to bear in mind that quieter recordings may need to be amplified even more. We’ve used a simple method here to select the gain, which avoids the use of potentiometers. After all, the MP3 player already has its own volume control. We decided to have two gain settings on the booster, one of three times and the other ten times. Amplifiers IC1A and IC1B (for the right and left channels) are housed in a single package, a TS922IN.

The output signal of the MP3 player is fed via a stereo cable and socket K1 to the inputs of the amplifiers. The gain depends on the relationship between resistors R2 and R1 (R6 and R5 for the other channel) and is equal to ten times. When you add jumper JP1 (JP2), resistor R3 (R7) will be connected in parallel with the negative feedback resistor R1 (R6), which causes the gain to be reduced to about three. When you start using the booster you can decide which gain setting works best for you.

Circuit diagram:

MP3 Booster Circuit Diagram

Resistor R4 (R8) takes the amplified MP3 signal to the output socket K2 (K3). A cable then connects these phono sockets to the input of your power amplifier. The resistors connected in series with the output (R4 and R8) are there to keep the booster stable when a long cable is connected to its output. Cables have an unwelcome, parasitic capacitance. This capacitive effect could (due to phase shifts of the signal) affect the negative feedback of the booster in such a way that a positive feed back occurs, with the result that the booster oscillates and possibly damages the power amplifier!

The resistors (R4 and R8) effectively isolate the output of the booster from the parasitic capacitance of the output cable. They also protect the booster outputs from short circuits. We’ve used a TS922IN opamp in this booster because it can operate at very low supply voltages (the maximum is only 12 V!), but can still output a reasonable current (80 mA max.). For the supply we’ve used rechargeable batteries (e.g. NiCd or NiMH cells) so that we don’t need a mains supply.

To keep the number of cells required as small as possible, we’ve chosen a supply voltage of 5 volt; this can be supplied by four rechargeable batteries. It is also possible to use four ordinary, non-rechargeable batteries; it’s true that the supply voltage then becomes a bit higher (6 Volts), but that won’t cause any harm. Since we’ve used a symmetrical supply for the booster (2 x 2 batteries), it will be easiest if you use two separate battery holders, each with two AA cells. The two holders are connected in series.

Make sure that the batteries are connected the right way round; the positive of one always has to be connected to the negative of the next. This also applies to the connection between the two battery holders. S1A/B is a double pole switch, which is used to turn both halves of the battery supply on or off simultaneously. If you can’t find the (dual) opamp we’ve used (or an equivalent), you could always use standard opamps such as the NE5532, TL082 or TL072. These do need a higher supply voltage to operate properly. In these cases you should use two 9 V batteries and replace resistor R9 with a 15 kΩ one.

Do take care when you connect the circuit to your power amplifier because the output signal can be a lot larger and you could overload the power amplifier. (Although you’re more likely to damage the loudspeakers, rather than the amplifier!) (Please note that these two 9 V batteries can’t be used as a supply for the TS922IN!) In our circuit we’ve used a stereo jack socket for the input and phono sockets for the output because these are the most compatible with MP3 players and power amplifiers respectively. If you wanted to, you could solder shielded cables directly to the circuit instead, with the correct plugs on the ends. You’ll never find yourself without the correct connection leads in that case!

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Simple Mic Booster Circuit Diagram

This is a Simple Electronic Mic Booster Circuit Diagram. Anyone who’s spent much time searching the web for interesting circuits is likely to have found at least one TL431 based audio amplifier, the circuit being based on the principle that any comparator can be used in linear mode if it’s rolled off with enough negative feedback. Although the TL431 is often referred to as a programmable or adjustable zener, it is in fact a comparator with it’s own 2.5 V reference all neatly wrapped up in a TO92 package.

The problem with the TL431 amplifiers to be found on the web is that they simply roll it back with large nfb and leave it at that, which results in ver y low gain, to make mat ter s worse some such circuits make a bit of a hash of biasing the control input.

Electret Mic Booster Circuit Diagram

The circuit presented here takes care of the low gain by adding an AC shunt to the feed-back path and using an electret mic for the input the 2.5 V set on the control input at stable operating condition suits an electret mic per fectly. The first prototype had a 35 ohms loudspeaker as a load (RL), this gave good results although the TL431 ran a bit warm with a Vccof 12 V. An old 130 ohm telephone earpiece is likely to present a less stressful load. AC shunt C2 (100 µF) has to be a quality component in terms of its ESR specification don’t just use a scruffy capacitor lying about as you may experience RF sensitivity. It was necessary to add a series resistor (R3; about 100 ohms) or in extreme cases an inductor (L1; 100 – 220 µH).
.

Components C1 & R1 are entirely optional to selectively feed some unshunted feedback to reduce noise; 1.5 k? & 5.6 nF are as good a place as any to start off with. Initial set-up depends on the current drawn by the electret mic and the value for RL any-where between 200 and 2,000 ohms is good. R2 allows the TL431 cathode to swing despite the AC shunt, 1.2 k? was found to be satisfactory, P1 can be a 47 k? trimpot and is used to set the voltage drop on RL. In the case of moving coil speakers a compromise between volt-age swing and prebiasing the cone should be sought, with a resistive load adjust for 0.5 Vcc, once the operating point is determined P1 can be measured and replaced by an equivalent fixed resistor.

The circuit has a couple of handy features, firstly it wor k s ver y well on the end of a twisted-pair the output can be tapped off at the wiper if RLis a pot at the power supply end, secondly by salvaging the JFET from an old electret mic (some common types of JFET will work but not quite as well), just about any piezo electric element can be used as the transducer. Brass disc sounders give a good output (handy as vibration sensors if glued to a structure); even the quartz discs from clock crystals give some output, a phono crystal cartridge gives a high output and the piezo-ceramic pellet from a flintless cigarette lighter gives a huge output... the range of possible applications is awesome!

A surprising application is the ability to test the microphonic sensitivity of ordinary capacitors! Disc ceramic types don’t need to be tapped very hard to produce an output but rolled metalised foil types produce some out-put too. Link

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