Various diagram

As the amplifier circuit also uses a number of frequencies to drive the loudspeaker, the bass frequencies will be reduced. Therefore need to be plugged the bass-boost control at fedback loop amplifier, this is done to overcome the decline in quality.


Graph bass can reach a maximum at +16.4 dB @ 50Hz.

A simple shortwave radio detector is neither very sensitive nor very selective. However, with a little extra amplification we can improve the reception performance significantly.

The additional circuit is designed to compensate for the losses in the resonant circuit. A transistor is used to amplify the RF signal and feed it back into the resonant circuit. When the gain is set correctly we can make the amount of this feedback exactly equal to the losses. The resonant circuit is then critically damped and has a very high Qfactor. Now we can separate transmissions that are just 10 kHz apart, and we can tune in to very weak stations.

The tuning capacitor used has two gangs of vanes with capacitances of 240 pF and 80 pF. These two gangs are connected in parallel to make a 320 pF variable capacitance. The air-cored inductor has 25 turns on a diameter of 10 mm, with taps at 5-turn intervals. The resonant circuit so formed is capable of covering the full shortwave  band from 5 MHz to 25 MHz.

The short wave detector can be connected to a power amplifier, or, for exam-ple, amplified PC loudspeakers. The antenna does not have to  be very long: in experiments we used a one metre length of wire. Tuning the radio involves adjusting the variable capacitor to bring in the station and then adjusting the gain of the feed-back circuit for optimal output volume. If the potentiometer is turned up too far, the receiver will go into self-oscillation and become a mini-transmitter. At  the optimal setting the sound  quality is very pleasant and certainly no worse than many ordinary shortwave radios.

If you find shortwave detectors that use a battery and an amplifier a little new-fangled, you can get your fix of nostalgia by dispensing with the battery and connecting a crystal earpiece to the detector’s output. The radio will of course also work without the feedback circuit, but with rather poorer performance.

LG is presenting streak new cell before IFA 2014 Earlier this week the company introduced the LG Stylus G3 to challenge the Samsung Galaxy Note, but apparently thats not all you have prepared and presented the LG Gx2, which can be easily confused with the LG G2x years ago.

The new LG cell Gx2 also wants to enter the territory of the Samsung Galaxy Note to have a 5.7 ​​inch screen, but its specifications are still being average and not high end.

Gx2 LG screen has a resolution HD (720p), a quad-core 1.2GHz processor, 1.5GB of RAM and 8GB of storage.

Additionally, the cell has a ATTERY of 3,200mAh, a rear 8 megapixel camera, 1.3 megapixel front camera and battery 3,200mAh. The rear camera has the same technology found in the LG G3, mainly the laser autofocus.

LG has not announced when it would be released in that country and what would be its price. However, there is the possibility that, for the moment, leave only in Asia, but do not rule out the possibility of reaching other markets in the future.

Some of you might wonder why a charger is needed at all, to charge a 12 Volt battery from a 12 Volt source! Well, firstly the "12 Volt" source will typically vary anywhere from 11 Volt to 15 Volt, and then a battery needs a controlled charge current and voltage, which cannot result from connecting it directly to a voltage source. The charger described here is intended for charging small 12 Volt lead acid batteries, such as the gelled or AGM batteries of capacities between about 2 and 10 Ah, using a cars electrical system as power source, regardless of whether the car engine is running or not. I built this charger many years ago, I think I was still in school back then. On request of a reader of my web site, Im publishing it now, despite being a rather crude circuit.


It works, it is uncritical to build, and uses only easy-to-find parts, so it has something in its favor. The downside is mainly the low efficiency: This charger wastes about as much power as it puts into the battery. The charger consists of two stages: The first is a capacitive voltage doubler, which uses a 555 timer IC driving a pair of transistors connected as emitter followers, which in turn drive the voltage doubler proper. The doubler has power resistors built in, which limit the charging current. The second stage is a voltage regulator, using a 7815 regulator IC. Its output is applied to the battery via a diode, which prevents reverse current and also lowers the voltage a bit.


The resulting charge voltage is about 14.4V, which is fine for charging a gelled or AGM battery to full charge, but is too high as a trickle charger, so dont leave this charger permanently connected to a battery. If you would like to do just that, then add a second diode in series with D3! There is a LED connected as a charge indicator. It will light when the charge current is higher than about 150mA. The maximum charge current will be roughly 400mA. There is an auxiliary output, that provides about 20V at no load (depending on input voltage), and comes down as the load increases. I included this for charging 12V, 4Ah NiCd packs, which require just a limited current but not a limited voltage for charging.


Note that if the charge output is short-circuited, the overcurrent protection of U2 will kick in, but the current is still high enough to damage the diodes, if it lasts. So, dont short the output! If instead you short the auxiliary output, the fuse should blow. I built this charger into a little homemade aluminum sheet enclosure, using dead-bug construction style. Not very tidy, but it works. Note the long leads on the power resistors. They are necessary, because with shorter leads the resistors will unsolder themselves, as they get pretty hot! The transistors and the regulator IC are bolted to the case, which serves as heat sink. The transistors dont heat up very much, but the IC does.

Source: Homo Ludens

This is the schematic design of HiFi Expandor Circuit with De-emphasis. The circuit is based NE570. The NE570 can be used to construct a high performance compandor suitable for use with music. This type of system can be used for noise reduction in tape recorders, transmission systems, bucket brigade delay lines, and digital audio systems. The circuits to be described contain features which improve performance, but are not required for all applications.

Someone just got this trick works on all the uni body Mac Books and helps keep your wires and cord under control.



This clip is especially bendy if you are lounging on the sofa with the power-cord-side in towards the cushions. It keeps your MacBooks power cord under control with this trick and to stop it from tugging in you. Its built-in cable clip the one that keeps your cord wrapped around the power brick and clip it to the side of your laptops screen.

The cable pulls it up off your lap and keeps it neat and tidy not to mention free of crazy fall across the keyboard loops.

Compressor Circuit with 570/571 Compandor IC schema provide high gain for low amplitude input and provide low gain for high amplitude input. This action, in effect, produce a nearly constant amplitude even though the input has very high dynamic range (very high amplitude variation from time to time). The action of compression like this is needed in some situation, such as in maximizing modulation depth in broadcasting, or sustaining electric guitar signal which has very high variation between the plucking time and fading out.  The following schema has complementary input/output characteristic and unity gain at 0.775 VRMS input. Voltage gain through compressor is square root of 0.7/Vin. Vin is average input voltage. This schema  uses Signetics dual channel compandor IC.  570 has lower inherent distortion and higher supply voltage range (6-24 V) than 571 (6-18 V).