Mini Portable Guitar Amplifier Circuit

Mini Portable Guitar Amplifier Circuit

This mini amplifier was meant to be used in conjunction with an electric guitar to do some monitoring of low consumption, mainly for practice, either through a small speaker or headphones. The complete circuit, speaker, batteries, input and output can be locked in a small box the size of a pack of cigarettes, or can also be installed in a real pack of cigarettes, as some units and made available on the market .

This design can be used in three ways:

• Loudspeaker amplifier: when powered by a 9V alkaline battery it can deliver about 1.5W peak output power to the incorporated loudspeaker.
• Headphone amplifier or low power loudspeaker amplifier: when powered by a 3V battery (2x1.5V cells) it can drive any headphone set type at a satisfactory output power level or deliver to the incorporated loudspeaker about 60mW of output power. This configuration is useful for saving battery costs.
• Fuzz-box: when powered by a 3V battery (2x1.5V cells) and having its output connected to a guitar amplifier input the circuit will behave as a good Fuzz-box, showing an output square wave with marked rounded corners, typical of valve-circuits output when driven into saturation.

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CAR POWER FILTER REGULATOR USING LM1084

 Sometimes may built-in babble botheration has from electricity auto system. I thinks Power Clarify Regulated for car by LM1084-12 may advice break a botheration this get. Because of application way LC clarify and IC LM1084-12 (5A Low Dropout Positive Regulators) as a aftereffect can advice adapt voltage well. If there is beat babble 12V added although a little aloof will change this ambit has a little. And this ambit still can accord the trend alpine arrives at 5A can administer to the accessories awning very.

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Light Level Droplets Detector Circuit

Here’s a design circuit for Low-Light Level Drop Detector. This circuit utilize self-biasing configuration to detect small changes in light level. This circuit usually used in monitoring very low droplets rates. The collector of the transistor gives feedback that is used to stabilize the bias of the photo darlington. This is the figure of the circuit;

 

The effect on optical performance is reduced by a high base-source impedance that is produced by The 10-μF capacitor and 10-MΩ resistor. When there is a liquid drop is detected by the detector, the light that reach the chip is momentary decreased causing collector voltage to momentarily rise, then output signal is generated. Due to mechanical spacing system constraints and output power constraints on the LED, the initial light bias is small. A fraction of this  initial bias is the change in light level. This fraction is caused by stray light paths and drop translucence. When biased, the output signals level is still acceptable because the photodarlington  has high sensitivity. This compares with unacceptable bias point stability and signal levels when biased conventionally, like signal output across the collector bias resistor and base open. [Circuit diagram source: seekic.com]

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Constant Current LED Driver Circuit

 If an LED is used in a circuit, the current for that LED is normally set with a limiting resistor. The LED can then be switched on and off by means of a transistor.
The following discussions explains a transistor based configuration which ensures a constant current drive to the conected LEDs, under  all circumstance.

However, the method shown in figure l does not take into account any variations in the supply voltage. A small variation in the LED current can be very conspicuous especially when high efficiency LEDs are used. The addition of just one transistor can transform the circuit of figure 1 to a onstant current source which can be switched on an off (for instance, with TTL levels). The circuit of figure 2 shows that resistor R1 has been moved to the emitter of T1. When a drive voltage is applied to the input of T1, this transistor conducts which causes a current through R1. Transistor T2 controls the base current of T1 such that I the voltage drop across R1 remains at 0.6 V. The current, l, through the LEDs and R1 is calculated by l= 0.6/R1. lf, for instance, R1 is 12 S2, the current through the LEDs is 50 mA. Bear in mind that the dissipation of T1 is somewhat higher than in the circuit of figure 1, but against that, the dissipation in R1 is not as high.

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Refrigerator Thermostat Circuit Using IC 741

Refrigerators dissipate the heat extracted from the inside via a grid structure mounted at the rear side. When a refrigerator is located in a confined space, the rear side can get fairly hot owing to the limited convection.
This problem derates the overall efficiency of the refrigerator, since the motor is automatically switched on for longer periods when a considerable difference exists between the inside and outside temperature notably on hot days it often seems as if the motor is running continuously. The ventilation control described here can help economize on power consumption.

The circuit is simple, and does not require a detailed description. A simple DC supply is set up with Tri—C1. Temperature is measured with the aid of bridge circuit R1-R2-P1 and a NTC (negative temperature coefficient resistor). IC1 is a comparator which converts the bridge output into a gate current for triac Tri, which controls extractor fan M. Some hysteresis is provided by feedback resistor Ra. The triac is controlled with a direct gate current to avoid triggering problems arising from induced voltage peaks. The circuit is uncritical as regards construction. Be sure to observe the correct connection of the al and a2 terminals on the TIC206, else it remains trig-  gered permanently. It should be noted that the circuit is dangerous to touch, as it is connected direct to the mains. It is possible to reduce the stand-by  current by omitting Tri, and powering the circuit in parallel with the refrigerator motor. The NTC should be fitted near the grid at the rear side of the  refrigerator. The triac can do with without a heat-sink.

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How to Make a 40 watt Single Chip Amplifier Circuit

Philips have developed the Type TDA1514 AF amplifier chip, which is remarkable for its l excellent specifications, ruggedness and output power.

The circuit diagram shows that very few components are . needed to make this high- performance amplifier.

The device is housed in a 9-pin SIL POWER enclosure which has a thermal resistance of less than 1.5 K/W so that the heatsink required must have a thermal resistance of no more than 3.8 K/Wif the chip is operated at its maximum dissipation of l9 W (Ub= i-27.5 L Ta=5O °C).

The power supply to feed the chip must be capable of delivering a current of at least 3 A; the quiescent current demand of the amplifier as shown is about 60 mA.


Make sure, however, that the tracks and connections to the Sl i supply and output terminals are as short as possible, and use H double tracks where this is I necessary. In this context, it is advisable to fit decoupling 5 capacitors C3 and Ca as close as 3 possible to the chip supply  pins. Resistors R2 and R3. 

The supply voltage 1 should not exceed +/-27.5v. Although this project is not supported by a ready—made printed circuit board, you should not C experience too much difficulty  in constructing the amplifier if it F $ is built on a piece of Veroboard.

Courtesy: Elektor Electronics

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How to Make an Adjustable Zener Diode Circuit with Stable Output

As everybody knows the voltage drop across a zener diode is dependent on the current passing th rough the diode.
Therefore, depending on the type and power of the device, there can be very noticeable deviations from the nominal zener voltage. This can be a problem, especially in circuits where a stable d.c. voltage is essential. The most logical way of solving the problem is to keep the current through the diode constant so that the zener voltage can not change. ln order that the load connected to the zener diode draws a constant current, the zener can be supplied by means of a current source. Then the current through the current source is made dependent on the zener voltage. In our adjustable zener circuit we use a zener diode with a zener voltage of 6 V. Other zener values could be used if resistors R1 . . . R4 are changed to suit another value. The maximum input voltage is mainly limited by the power which can be dissipated by T1 and T2. The d.c. input voltage must be at least as high as the sum of the zener voltages of Dl and D2.

The current source consisting of T1, R1 and D1 ensure that the current through D2 remains constant. Transistor T2, resistor R 2 and zener diode D2 in turn form a current source for zener D1 so that the current through this diode also stays constant. Diode D3 and the voltage divider, consisting of R3 and R4, ensure that this circuit can ’start’ (just as a thyristor made of transistors). As soon as the voltage is switched on a current flows through D3 causing T2 (and therefore T1) to conduct. The value of R3 must be selected such that diode D3 blocks as soon as the voltage across the zener dlode has stabilized. So care must be taken that the voltage at the anode of D3 ls less than the zener voltage of D2 plus the di0de’s own voltage drop of 0.6 V. This is defined by the formule: ; x U;

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