Tuesday, February 4, 2014

Build a Tremolo Effect Circuit Diagram

This tremolo effect circuit uses the XR2206 and the TCA730 IC which is designed as an electronic balance and volume regulator with frequency correction. The circuit is use full for stereo channels and it also has the ability to simulate the Lesley effect aka rotating loudspeaker effect.

How does the tremolo effect circuit works
Balance and volume settings are done with a linear potentiometer for both channels. If this potentiometer is replaced with an AC voltage source, a periodic modulation of the input signal can be achieved. This AC voltage source comes from the function generator IC XR2206. This IC generates square, triangle and sine wave signals but for this project we use only the sine wave.

IC  Tremolo Effect Circuit Diagram

 Tremolo Effect Circuit Diagram

The modulation voltage can be varied with P1 from 1 Hz up to 25 Hz. Resistor R3 sets the operation level of the sine wave generator. R5 and R6 set the DC voltage and the sine wave amplitude at the output. C2 is a ripple filter. The square wave output of the XR2206 drives T2 and a LED to optically display the frequency.

The modulating voltage reaches pin 13 of TCA730 via P3 and R10. This input functions as the volume control or in this case the volume modulation. The degree of the balance modulation (Lesley effect) can be varied with P2. A regulated power supply using 7815 IC is recommended. Do not use a non-stabilized power supply since the current variations would influence the modulation negatively.
Attach the 7815 IC to a good heat sink (about 10 cm2).
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Friday, January 10, 2014

Simple Auto Turn Off Battery Charger Circuit Diagram

This Auto Turn-Off Battery Charger Circuit Diagram for series-connected 4-cell AA batteries automatically disconnects from mains to stop charging when the batteries are fully charged. It can be used to charge partially discharged cells as well. The circuit is simple and can be divided into AC-to-DC converter, relay driver and charging sections. In the AC-to-DC converter section, transformer X1 steps down mains 230V AC to 9V AC at 750 mA, which is rectified by a full-wave rectifier comprising diodes D1 through D4 and filtered by capacitor C1. Regulator IC LM317 (IC1) provides the required 12V DC charging voltage.



 Auto Turn-Off Battery Charger Circuit Diagram

 Auto Turn-Off Battery Charger Circuit Diagram




When you press switch S1 momentarily, the charger starts operating and the power-on LED1 glows to indicate that the charger is ‘on.’ The relay driver section uses pnp transistors T1, T2 and T3 (each BC558) to energise electromagnetic relay RL1. Relay RL1 is connected to the collector of transistor T1. Transistor T1 is driven by pnp transistor T2, which, in turn, is driven by pnp transistor T3. Resistor R4 (10-ohm, 0.5W) is connected between the emitter and base of transistor T3.

When a current of over 65 mA flows through the 12V line, it causes a voltage drop of about 650 mV across resistor R4 to drive transistor T3 and cut off transistor T2. This, in turn, turns transistor T1 ‘on’ to energise relay RL1.


Now even if the pushbutton is released, mains is still available to the primary of the transformer through its normally open (N/O) contacts.  In the charging section, regulator IC1 is biased to give about 7.35V. Preset VR1 is used for adjusting the bias voltage. Diode D6 connected between the output of IC1 and battery limits the output voltage to about 6.7V, which is used for charging the battery.  Pushing switch S1 latches relay RL1 and the battery cells start charging. As the voltage per cell increases beyond 1.3V, the voltage drop across resistor R4 starts decreasing. When it falls below 650 mV, transistor T3 cuts off to drive transistor T2 and, in turn, cuts off transistor T3.


As a result, relay RL1 de-energises to cut off the charger and red LED1 turns off.  You may determine the charging voltage depending on the NiCd cell specifications by the manufacturer. Here, we’ve set the charging voltage at 7.35V for four 1.5V cells. Nowadays, 700mAH cells are available in the market, which can be charged at 70 mA for 10 hours. The open-circuit voltage is about 1.3V. The shut-off voltage point is determined by charging the four cells fully (at 70 mA for 14 hours). After measuring the output voltage, add the diode drop (about 0.65V) and bias LM317 accordingly.



Author : Y.M. Anandavardhana
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Thursday, January 9, 2014

Here will introduce a palm size cell phone jammers

The manufacture process and technology of cell phone jammers will be renewed and revised.
To pay a certain amount of calls per month, pay the full two years can have this phone and given 14 days probation period, if you are not satisfied, you can cancel the agreement, returned to the mobile phone network operators. This is our country, "China Mobile and China Unicom launched prepaid calls to send the phone is somewhat similar, the difference is more humane, the foreign service, you can have the 14-day trial period, if you use unhappy, and free exchange within 14 days of the other models, this machine without the network or not, you have the final say. All there is this machine 14 days. The machine fineness of good items fineness of 99 to 100%, all original accessories. The working instruction of cell phone jammers should be renewed too.
14 secret in a foreign country, tried, strictly speaking, not a new machine, it should be said to be filling the new machine; appearance is difficult to identify due to foreign network operators require the phone to fourteen days trial period can not be damaged, it will be net of depreciation expense, so a lot of fourteen days the machine appearance is unable to identify whether the new machine; concrete from several aspects: 1, the packaging is worn; a close look at the phone The charging port and battery with or without scratches headphones and related accessories to be opened too; 3, enter the mobile phone interface to see whether the call records and contacts with or without record. It is the three-antenna wireless signal cell phone jammers .Here will introduce a palm size cell phone jammers
Purchase Note: the 14 secret 14 secret and a new machine purchase price difference of $ 100-200, do not rule out some distribution will take the 14 secret when a new machine for sale, at the time of purchase must be carefully view; not all phones 14 secret, and generally there are 14 secret specific models are as follows: Nokia N-GAGE, Dopod 686, the XDA, the SIEMENS SX65, Dopod 515 (SPV) Sony Ericsson T610, Panasonic GD87, NEC, C616, C313, Motorola A835, a920 models . Trigger is also the last one to two years to appear. The so-called trigger is assembled machine. Outflow from the mobile phone production factory accessories by skilled workers, self-assembly sales. Here will introduce a new type of three antenna wireless signal cell phone jammers .
For example, the past two years the fire of the Sony Ericsson T618, factories located in Beijing, workers tried a variety of ways to take the accessories directly from the pipeline, and then brought back home, assembled, sold to wholesalers. This phone a lot of accessories do not go through quality inspection, so the quality is uneven, and definitely do not recommend the purchase. On one of the phones the difference between parallel and mainstream. First affirmed either parallel or licensed, are regular manufacturers. Parallel does not mean that products mixed with water made a false parallel as counterfeit, counterfeiting, the degree of integration of mobile phone technology is not yet behind to make people imitation, unless it is a OEM product, for example, Kejian and Samsung. Lenovo and LG, Capitel, and Nokia, and so on.  cell phone jammers is recently well received by the customer in the domestic market and oversea market.
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Simple Switching Regulator Converter Circuit Diagram

This is a Simple Switching Regulator Converter Circuit Diagram  . The Max650 switching regulator produces a regulated 5 V from large negative voltages, such as the -48 V found on telephone lines. The resulting power supply operates with several external components, including a transformer, and it delivers 250 mA. The device includes a 140-V 250-mA pnp transistor, short-circuit protection, and all necessary control circuitry.

Simple Switching Regulator Converter Circuit Diagram

Simple Switching Regulator Converter Circuit Diagram

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Friday, December 27, 2013

The main body of cell phone jammer should be installed on the top

 Personality, social factors and individual background variables on the mobile phone text messages have a certain psychological predictors. Personality, social factors and individual psychological background variables through SMS mobile phone text messages as an intermediary variables on the use of the Indirect impact. While the extraversion personality and sense of responsibility can also be used directly to predict behavior of mobile phone text messages.  Study were 475 valid questionnaires, which have cell phones, the number of people using SMS 81.5%. And consistent with previous findings, gender, whether to use SMS, SMS cost ratio and the number of SMS sent in did not show significant differences in the impact of family origin is an important factor in the use of SMS. To the individual background variables, social factors and Big Five personality as a predictor variable, the need to make friends as the dependent variable for multiple regression analysis, the results can be found not found the variable into the regression equation, indicating that these variables can not predict the respondents from the phone SMS in the need to make friends. The personal, social, and psychological factors can not only directly affect the behavior of SMS use, but also indirectly through the psychological impact of mobile phone SMS text messaging usage behavior. The more visualized explanation is that the requestor is serially connected with the power end of cell phone jammer . In addition, the various dimensions of social support through the impact on the understanding of the prevalence of mobile phone text messages, SMS can also affect the adoption, but the indirect effects of several sub-dimensions there are also negative, temporarily unable to identify its overall impact. SMS students and levels of consumption structure is relatively simple, the impact SMS consumption, the main factor is price, followed by the SMS unique expression. Students send SMSs main target is family and friends, mainly for blessings class, the purpose is to increase contact and exchange feelings, access to information. SMS mobile phone costs account for the proportion of expenditure generally below 50%, generally in the week to send the number 50 below. The main body of cell phone jammer should be installed on the top inside the box with the antenna coming out of the box body.
Nokias highly trained staff has been reflected in the market. From the service side, the customer believes that Nokia service personnel trained, professional and standards. However, we believe that Nokias personnel training system although very advanced, but which lack a very important factor, that is humane. The results from the previous market research, we learned that the customer is usually very reliable service with Motorola phones Nokia, but Nokia mobile phone service although professional but not much expression. Instead of Motorola employees in the "smile" of the relative place. Nokia Corporation (Nokia Corporation NYSE: NOK) is a multinational mobile communications products, headquartered in Finland. In the mobile phone market, Nokia has for years occupied the market share position.


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Portable Microphone Preamplifier

High headroom input circuitry, 9V Battery operation

This circuit is mainly intended to provide common home stereo amplifiers with a microphone input. The battery supply is a good compromise: in this manner the input circuit is free from mains low frequency hum pick-up and connection to the amplifier is more simple, due to the absence of mains cable and power supply. Using a stereo microphone the circuit must be doubled. In this case, two separate level controls are better than a dual-ganged stereo potentiometer. Low current drawing (about 2mA) ensures a long battery life.

Circuit Operation:

The circuit is based on a low noise, high gain two stage PNP and NPN transistor amplifier, using DC negative feedback through R6 to stabilize the working conditions quite precisely. Output level is attenuated by P1 but, at the same time, the stage gain is lowered due to the increased value of R5. This unusual connection of P1, helps in obtaining a high headroom input, allowing to cope with a wide range of input sources (0.2 to 200mV RMS for 1V RMS output).

Portable Microphone Preamplifier Circuit diagram:
Portable Microphone Preamplifier Circuit Diagram

Parts:
P1 = 2.2K
R1 = 100K
R2 = 100K
R3 = 100K
R4 = 8.2K
R5 = 68R
R6 = 6.8K
R7 = 1K
R8 = 1K
R9 = 150R
C1 = 1uF-63V
C2 = 100uF-25V
C3 = 100uF-25V
C4 = 100uF-25V
C5 = 22uF-25V
Q1 = BC560
Q2 = BC550

Notes:
  • Harmonic distortion is about 0.1% @ 1V RMS output (all frequencies).
  • Maximum input voltage (level control cursor set at maximum) = 25mV RMS
  • Maximum input voltage (level control cursor set at center position) = 200mV RMS
  • Enclosing the circuit in a metal case is highly recommended.
  • Simply connect the output of this device to the Aux input of your amplifier through screened cable and suitable connectors.

Source :  http://www.ecircuitslab.com/2011/06/portable-microphone-preamplifier.html
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Solar Panel Voltage Regulator

Our energy-hungry and environmentally aware society has been slow to make good use of the suns "free" power. But now its finally taking off. Using the suns heat directly, for cooking and other applications, is already a common and popular technology in countries that have good weather. Hot-water panels are nowadays used in many parts of the world, in combination with a gas or electric powered water heater to help out when the weather doesnt help.

But at the same time, electric solar panels are still expensive, justifying their use only as a novelty, or in locations where little power is needed, and bringing in commercial power would be even more expensive. A solar electric power system needs panels for generation, batteries for storage, a regulator to keep the batteries within a safe operating range, and in some cases a power converter for AC output.

For those who need to set up a few panels for a summer cottage, a boat, a remote mountaintop installation, or whatever, Im herewith providing a version of the regulator circuit that I have used in a lot of such installations. Such a solar panel regulator should perform at least two operations: The obvious one is protecting the battery from overcharge at times of strong sun and little consumption, and the other is protecting it from excessive discharge in bad weather conditions. Both overcharge and deep discharge are harmful to a battery.

Circuit Project: Solar Panel Voltage RegulatorFor regulating a solar panels output, there are several possible ways. A linear series regulator can be used, but has the disadvantage of causing some voltage drop and having some internal power consumption at times when the sun is weak and the load is heavy. Its much better to use a shunt regulator, which is inactive at such times, and springs to life only when there is excess energy. For this reason, most solar panel regulators use the shunt scheme, the one presented here being no exception.

But such shunt regulators come in two flavors: Most commercial units are ON-OFF regulators. That means, they have a simple switch device, most often a transistor or MOSFET, sometimes even just a relay, that stays off until the battery reaches over voltage, and then switches in, shorting out the panel until the battery voltage has dropped off. Then the full panel current is switched on again. The only advantage of this method is thats cheap. The power switch operates with very low power dissipation, allowing a small, low cost construction.

But the disadvantages of this system are major: The voltage output is all the time fluctuating between about 13 and 14.5V. The battery is cycling between getting overcharge and having to deliver all the load current, which severely reduces the batterys lifetime. And in the event of battery disconnection or failure, the regulator cycles quickly, applying pulses of full panel voltage to the output, which can destroy sensitive equipment powered by the system!

The circuit presented here uses linear shunt regulation. Simply spoken, it burns off all excess energy from the panel, keeping output voltage constant. At times when the solar panel output is equal or greater than the load, and the battery is fully charged, the load gets its power from the panel, while the battery rests at full charge. Five years battery lifetime are entirely normal with this system, while the same batteries last only two to three years when used with pulsing regulators!

The second responsibility of the regulator is watching over the battery voltage, and dropping off the load when the battery gets discharged too much. Lead batteries are severely damaged by deep discharges, so its far preferable to drop off the load, then to have the battery die in a bad weather spell. This regulator is designed for 12V systems employing panels of up to 7A total current, and loads of not over 20A. It can be easily modified for greater currents.

U1A compares an adjustable sample of the present battery voltage to a 5V reference from a highly stable source. According to the result, it controls the power transistors Q1 and Q2, which shunt off the excess power generation from the panel. A diode (D1) avoids battery voltage to go back to the panel under no-light condition. To avoid imprecise voltage control due to varying diode drop, the sample is taken from the battery side, even if this means a very small power waste.

The power resistors R1 and R2 are dimensioned in such a way that under maximum shunting, these resistors will dissipate almost all power (about 100W total), leaving the transistors running cool. The highest dissipation in the transistors happens when the regulator is dissipating half of the panel output; in this case, each transistor will dissipate about 12W.

U1B is a Schmitt trigger that compares the battery voltage to the same stable reference of the other section, but for another purpose: It controls the load switch Q3. This circuit will disconnect the load if the battery gets close to deep discharge, and reconnect it only when recharge is well underway. The negative side of the load is switched, simply because N-channel MOSFETs are much cheaper and better than P-channel ones.

Component notes:

D1 can be any diode that can safely survive the panels current. If the panel has a very low voltage output (less than 33 cells in series), it is an advantage to employ a Schottky diode in this place. Q1 and Q2 are common power Darlington transistors. They need to be heatsinked for safe long-term operation at the 12 Watt dissipation level. Thats easy enough to do, but many newcomers misjudge how much thermal resistance is introduced by a mica insulator! Plan on 1K/W thermal resistance inside each transistor, two times as much in the insulator (if you use any), and 370K safe junction temperature. For typical environmental conditions, this makes you need a heatsink having a thermal resistance of about 1.3K/W. If it is larger, you get more safety margin.

R1 and R2 will have to be made by combining a number of power resistors in parallel. Yes, you need to make two resistor arrays of 4 Ohm, 80W each! This 80W figure includes a reasonable safety margin. These resistors will produce a lot of heat, and you may cook your coffee on them! Be sure to mount them in such a way that they have lots of ventilation, and that the heat from them will not reach the other components. R3 and R4 may to have be built from parallel combinations too, because of the low value of only 0.15 Ohm.

U2 is a voltage reference IC. You cannot replace it by a standard Zener diode! Zeners are much too unstable! If you cant find this chip locally, you may use the ubiquitous 7805 regulator instead, but the power drain from the battery will be higher. In this case, of course you dont need R8, but you would need a 1uF capacitor at the 7805 output. Q3 is a power MOSFET that has a very low Rds(on). You may use a different one, provided that it has a resistance thats low enough for your application. You may use several in parallel. The one I used has low loss even at loads of 20A, and can handle much more!

Calibration:

Once the circuit is assembled, calibration is quite easy. Connect the panel, leave the battery and load disconnected. With a nice sun on the panel, adjust RV1 for the desired voltage at the battery output. I recommend 13.8V for sealed batteries, and 14 to 14.2V for open cell ones, to which water can be added if necessary.

Now you need either a variable power supply connected to the battery lines, or some kind of variable load. You may also use your panel as variable power supply, by tilting it away from the sun while a fixed load is connected to the battery lines. The idea is to adjust the voltage at the battery lines to the desired shut-off value (I recommend 11.5V), and then move RV2 until Q3 shuts off, as indicated by a voltmeter across the load output, a 12V light bulb, or whatever you can use to detect it.

After Q3 has shut off, increase the voltage across the battery lines and see at which level Q3 switches on again. This should happen above 12.6 and below 13.4 V. You may have to retouch RV2 and look for a compromise between ON and OFF voltages. If your components are not too much out of value, then both potentiometers should have ended up reasonably close to the center position.

Using more panels:

You can use this regulator for larger installations. Simply add one group like R1-Q1-R3 for each additional 3.5A panel, and use a diode for D1 that handles the total current. Remember that large diodes need heat sinks! U1A can drive at least 8 such transistors. If you intend to build a really large system, you may want to add an emitter follower between U1A and the power transistors. If you need to handle large load currents, you can place as many MOSFETs in parallel as you need. There is no practical driving limitation in this case. [via]
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