Subwoofer Filter and Low Pass Filter with LM741

The acoustics of converting a filter, there are many aspects of the economic viability of the more famous are baxandal filter low and high frequency filters and crossover Acoustic space is transformed into sub-domains, so that the Thursday Speakers. Applications, we offer a filter, the limits of the region to transform acoustic (20-20000Hz) in the region of 20-100Hz.

Subwoofer Filter and Low Pass Filter Circuit Diagram

The signal for a first high pass filter C1, C2, P1, which is undesirable level DC input. A lowpass filter consisting of R3, R4, C3 prevents frequencies above 10 kHz, which do not benefit from this design, and it would be that the instability and noise. The summary amp invert signal.

The low Summary of the amplifier signals go to a second low-pass filter to prevent the frequency from the speakers. I decided, a second order, as this box with a closed place feature. If you have a circuit with a valve system, and then simply close the Wind (Roll a pair of socks and pick at the port / Wind), this will give you a sealed box instead.

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A Low Cost Hearing Aid Circuit

Small and transportable unit, Useful for previous men and previous women

This most economical, general-purpose electronic hearing help works off 3V DC (2x1.5V battery). The circuit will additionally be simply assembled on a veroboard. For easy assembling and repairs, use an 8-pin DIP IC socket for TDA2822M.

Circuit Diagrams:

 A Low Cost hearing Aid Circuit

Parts:
P1 = 10K
R1 = 2.2K
R2 = 330K
R3 = 680R
R4 = 33R
R5 = 100R
R6 = four.7R
R7 = 4.7R
R8 = 220R
C1 = zero.01uF-10V
C2 = 100nF-63V
C3 = four7uF-10V
C4 = 10uF-10V
C5 = 0.01uF-10V
C6 = 100uF-10V
C7 = 100nF-63V
C8 = 100nF-63V
D1 = Red LED
Q1 = BC547
IC1 = TDA2822M
EP1 = Mono Earphone 32R
SW1 = On-Off Switch

Circuit Operation:

In this circuit, transistor Q1 and related elements kind the audio signal preamplifier for the acoustic signals picked up via the condenser microphone and transformed into corresponding electrical signals. Resistor R5 and capacitor C3 decouple the facility supply of the preamplifier stage. Resistor R1 biases the interior circuit of the low-voltage condenser microphone for correct working. The audio output from the preamplifier stage is fed to the input of the medium-power amplifier circuit by method of capacitor C2 and quantity keep watch over P1.

The medium-power amplifier section is wired round in style audio amplifier IC TDA2822M (not TDA2822). This IC, specially designed for moveable low-power utilitys, is readily available in 8-pin mini DIP bundle. Here the IC is wired in bridge configuration to pressure the 32-ohm general-purpose monophonic earphone. Red LED (D1) point outs the facility status. Resistor R8 restricts the running present of D1. The audio output of this circuit is 10 to 15mW and the quiescent present drain is below 1 mA.

Source : www.electronsforu.com

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Simple Low Drop 5V Regulator

A 4-cell pack is a convenient, popular battery size. Alkaline manganese batteries are sold in retail stores in packs of four, which usually provide sufficient energy to keep battery replacement frequency at a reasonable level. Generating 5 V from four batteries is, however, a bit tricky. A fresh set of four batteries has a terminal voltage of 6.4 V, but at the end of their life, this voltage is down to 3.2 V. Therefore, the voltage needs to be stepped up or down, depending on the state of the batteries. A flyback topology with a costly, custom designed transformer could be used, but the circuit in the diagram gets around the problem by using a flying capacitor together with a second inductor.

Circuit diagram:

The circuit also isolates the input from the output, allowing the output to go to 0 V during shutdown. The circuit can be divided conceptually into boost and buck sections. Inductor L1 and switch IC1 comprise the boost or step-up section, and inductor L2, diode D1 and capacitor C3 form the buck or step-down section. Capacitor C2 is charged to the input voltage, Vin, and acts as a level shift between the two sections. The switch toggles between ground and Vin+Vout , while the junction of L2, C2 and D1 toggles between –Vin and Vout +Vd1. Efficiency is directly related to the quality of the capacitors and inductors used.

Better quality capacitors are more expensive. Better quality inductors need not cost more, but normally take up more space. The Sanyo capacitors used in the prototype (C1–C3) specify a maximum ESR (effective series resistance) of 0.045 ½ and a maximum ripple current rating of 2.1 A. The inductors used specify a maximum DCR (direct current resistance) of 0.058 ½. Worst-case r.m.s. current through capacitor C2 occurs at minimum input voltage, that is, 400 mA at full load with an input voltage of 3 V. 

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Low Cost Universal Battery Charger Schematic

Low cost solution for charging of each NiCd and NiMh batteries

Here is the circuit diagram of a low price universal costr for NiCD - NiMH batteries. This circuit is Ideal for automobile use. It has capability to transform a primes adapter in to a costr . This one can be used to cost mobile phone, toys, moveables, video batteries, MP3 gamers, ... and has selectable cost present. An LED is situated in circuit to indicate charging. Can be built on a basic purpose PCB or a veroboard. I hope you in point of fact love it.

Picture of the circuit: 

 A Low Cost Universal Charger Circuit Schematic

Circuit diagram:

A Low Cost Universal Charger Circuit Diagram

Parts:

R1 = 120R-0...5W
R2 = See Diagram
C1 = 220uF-35V
D1 = 1N4007
D2 = 3mm. LED
Q1 = BD135
J1 = DC Input Socket

Specifications:

• Ideal for in car use.
• LED charge indication.
• Selectable cost current.
• Charges Ni Cd or NiMH batteries.
• Transforms a primarys adapter into a costr.
• Charge cellular phone, toys, transportables, video batteries …

Features:

• LED perform indication.
• Power provide polarity protected.
• Supply current: similar as cost current.
• Supply voltage: from 6.5VDC to 21VDC (depending on used battery)
• Charge present (±20%): 50mA, 100mA, 200mA, 300mA, 400mA. (selectable)

Determining the availability voltage:

This desk indicates the minimum and most voltages to supply the charger. See provide voltage choice chart under.

Example:

To cost a 6V battery a minimum supply voltage of 12V is needed, the utmost voltage is then 15V.

Voltage choice:

Voltage Selection Chart For Low Cost Universal Battery Charger

Determining the cost current:

Before constructing the circuit, you have to determinate how a lot present will probably be used to charge the battery or battery pack. It is a good suggestion to cost the battery with a present that is 10 occasions smaller then the battery capability, and to charge it for about 15 hours. If you double the charge current , then that you may charge the battery in half of the time. Charge present selection chart is positioned in diagram.

Example:

A battery pack of 6V / 1000mAh will additionally be charged with 100mA during 15 hours. If you need to charge quicker, then a cost present of 200mA can be utilized for approximately 7 hours.

Caution:

The larger cost present, the extra essential the cost time need to be checked. When faster charging is used, you should discharge the battery totally sooner than charging. Using a cost present of 1/10 of the capacity will increase the lifetime of the battery. The cost time can easily be doubled with out damaging the battery.

Note:

• Mount the transistor in conjunction with the heatsink on the PCB, bend the leads as important. Take care that the metal again of the transistor touches the heatsink. Check that the leads of the transistor don't touch the heatsink.

Source : http://www.ecircuitslab.com

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Easy Discrete Low Drop Regulator

This circuit was designed to ensure that an amplifier circuit containing a TDA1516Q would not exceed its maximum supply voltage when the load is small. This amplifier is used in a PC to increase the audio power somewhat. The PC power supply, however, created so much interference that an additional power supply was required.

Discrete Low-Drop Regulator Circuit Diagram

The power supply has its own power trans-former with a secondary voltage of 12 V AC. After rectification and filtering this results in a DC voltage of about 16 V. The regulator consists of a P-channel MOSFET SJ117, the gate of which is driven via a voltage divider connected to T2. The base of T2 is held at a constant voltage by LED D2, so that the volt-age across emitter resistor R2 is also constant and therefore carries a constant cur-rent. 

When the output voltage is higher than about 13.5 V, zener diode D1 will start to con-duct and supply part of the current through R2 — as a result the MOSFET will be turned on a little less. In this way there is a balance point, where the output voltage will be a little over 13.5 V (1.5 V across R2 plus the 12 V zener voltage). The regulator is capable of deliver-ing up to about 2 A — in any case it is a good idea to fit the MOSFET with a heatsink.

It is possible to add an optional potentiometer in series with the 12-V zener diode, which will allow a small amount of adjustment of the output voltage.The relay at the AC powerline input ensures that the power supply is only turned on when the PC is turned on. This relay is driven from a 4-way power supply connector from the PC. link

Author : Jac Hettema – Copyright: Elektor

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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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