LM3886 Amplifier Gainclone
LM3886 Amplifier Gainclone


LM3886 Amplifier Gainclone


Several years ago, National Semiconductor came up with some very high performance, easy to use audio power amplifier LM3886 circuits. I needed an extra amp so I can bi-amp some of my homemade electrostatic speakers so I tried the LM3886 chip. LM3886 amplifier was chosen because of ease of use, performance, low distortion and a built-in protection against short circuits and thermal instability. There is not much to remove a power amp, than asking. When driving electrostatic speakers, you can not be much protection. There are people who have “golden ears” and the feeling, provided that no application note scheme is never good enough for it to “Optimize” to “improvements” to make a claim. The problem is that most of them do not engineers and have no idea what the possible consequences of their “improvements” can be. For example, for a few years if these chips were popular with the audiophile crowd, it was all the rage at minimum power filter caps for “Best Sound” to use. We are talking about 500 uF on each power rail for each chip used LM3886 amplifier. This is clearly insufficient and leads to a distortion in the volume low enough that the power supply sags under load. The problem was that some of the golden ears of the large power supply rejection IC spec saw and thought it meant that the chip could tolerate the 10V power supply ripple. The pendulum has swung the other way, and now many music lovers are sufficient amounts of energy storage in the diet.

LM3886 Amplifier Gainclone

LM3886 Gainclone Amplifier Chip Amp Circuit Diagram

Another frequent change was the elimination of “Zobel” network with the output of the LM3886 amplifier, because it “sounded bad.” After a couple of people have burned some expensive speakers, they come to realize that the network is for the dead and the speakers sound much worse than the Zobel networks, so these days most people use the network Zobel. I used my amp to drive electrostatic speakers, a fee is particularly difficult because the capacitive reactance and never had any stability problems to delete.

My amp has been using a pattern from right to NS-sheet, with the additional power supply. Perhaps the mentality is to refine the model by manufacturers just do not understand the actual construction practices. One thing that is important for LM3886 is a good performance of an amplifier to use a proper ground. The ground is usually not represented in a diagram, because it is on the mechanical design of the circuit LM3886 amplifier chassis depends. Construction practices such as keeping high-impedance circuits (such as inputs of the amplifier) ​​and son of components by high currents (transformer, power supply and son traveled LM3886 amplifier output) and a “star” of the earth more high-performance-$ 10 resistance and gold plated connectors help. Click here for a schematic representation of the ground star

Normally, the housing is the most expensive part of the amplifier. It has to dissipate the heat from the amplifier and power supply integrated circuits of the transformer, you have to look acceptable and must be large enough to hold everything. My amp came from the housing, a scrap yard in Dallas, where I was able to buy it for $ 1 per pound or about $ 15. The box was originally a mobile phone antenna diversity housed the amplifier.

The side walls are 1 / 4 “thick aluminum, welded at the corners, making it a heavy box, a lot of heat can be dissipated. The top plate is 1 / 2″ thick and is equipped with fins covered dissipate heat even more. The bottom plate, not shown, is 1 / 8 “thick.

There were a number of ports through holes in the sides of the box. I could not use, but others, they were filled with Bondo putty. First I took a few bits of equipment containing PCBs in the box and then coated with Bondo into the hole from the outside. After curing the Bondo, I sanded the outer surface flush with the rest of aluminum. He has worked well and I recommend this technique for anyone who is recycling surplus assets.

I have a few holes where I needed him, enlarged some existing holes, then applied goal ..

One of my other hobbies is restoring old radios. I have a very special radio in my collection, a 1927 Super Six Neutrowound. The radio must have looked like he had the space back in 1927. At that time, most stations were simple, rectangular wooden boxes. This was a steel box with a very unusual view of the Ni-tube fitted covers that protrude from the top, and the exotic blue cracked painted orange!

I like the finish on the radio a lot, so I try to reproduce it on my LM3886 amp decided. Radio has been painted, but I do not have access to spray equipment, so I had to use brushes that apply to the target. I chose a beautiful blue metallic (not quite the same as the radio) and a bright orange for the base layer. The result was not a very good game for radio, but it was kind of interesting anyway.

The finishing steps were the beginning of the coat of orange acrylic-based, acrylic crackle medium, acrylic, metallic blue, and finally a layer of transparent acrylic protection.

Then came the construction of the LM3886 amplifier. The first channel is wired hay, because so few parts were needed, but I did not like the eyes of many, so that the second channel on perf board was built. The plan was eventually to go to circuit boards (later). All reasons to have a single “star” point was placed on the chassis to minimize the possibility of ground loops and associated hum / noise.

The transformer is a device may, 320VA one bit exaggerated since the amp about 30 watts per channel with the specified supply voltage.

The filter plugs into the socket about 100,000 uF total more than enough, but such a low voltage, capacity, cheap ($ 6 for a total of four choices), so why not?

The volume control is located near the entrance located at the back to keep the son of the Short-and signal from the transformer. The expansion of the tree is a piece of 1 / 4 “diameter brass tubing. Alignment of the tree volume and the hole on the front are not perfect, so I made an elastic coupling a piece of urethane tubing and two cable ties. It works well, when you turn the knob above the stopper into the pot, he slips a little, through an emphasis on the pot.

I finally got around to printed circuit boards and built the two LM3886 amplifier channels. I prefer the PCB since the circuits wired together with hay can cause short circuits if the son should be moved to make repairs.

Accurate LC Meter Capacitance Inductance Meter with 16F628 and LCD
Volt Ampere Meter with 16F876 Microcontroller and LCD display
Accurate LC Meter

Build your own Accurate LC Meter (Capacitance Inductance Meter) and start making your own coils and inductors. This LC Meter allows to measure incredibly small inductances making it perfect tool for making all types of RF coils and inductors. LC Meter can measure inductances starting from 10nH - 1000nH, 1uH - 1000uH, 1mH - 100mH and capacitances from 0.1pF up to 900nF. The circuit includes an auto ranging as well as reset switch and produces very accurate and stable readings.
PIC Volt Ampere Meter

Volt Ampere Meter measures voltage of 0-70V or 0-500V with 100mV resolution and current consumption 0-10A or more with 10mA resolution. The meter is a perfect addition to any power supply, battery chargers and other electronic projects where voltage and current must be monitored. The meter uses PIC16F876A microcontroller with 16x2 backlighted LCD.

50MHz 60MHz Frequency Meter / Counter with 16F628 & LCD
1Hz - 2MHz XR2206 Function Generator
60MHz Frequency Meter / Counter

Frequency Meter / Counter measures frequency from 10Hz to 60MHz with 10Hz resolution. It is a very useful bench test equipment for testing and finding out the frequency of various devices with unknown frequency such as oscillators, radio receivers, transmitters, function generators, crystals, etc.
1Hz - 2MHz XR2206 Function Generator

1Hz - 2MHz XR2206 Function Generator produces high quality sine, square and triangle waveforms of high-stability and accuracy. The output waveforms can be both amplitude and frequency modulated. Output of 1Hz - 2MHz XR2206 Function Generator can be connected directly to 60MHz Counter for setting precise frequency output.

BA1404 HI-FI Stereo FM Transmitter
USB IO Board PIC18F2455 / PIC18F2550
BA1404 HI-FI Stereo FM Transmitter

Be "On Air" with your own radio station! BA1404 HI-FI Stereo FM Transmitter broadcasts high quality stereo signal in 88MHz - 108MHz FM band. It can be connected to any type of stereo audio source such as iPod, Computer, Laptop, CD Player, Walkman, Television, Satellite Receiver, Tape Deck or other stereo system to transmit stereo sound with excellent clarity throughout your home, office, yard or camp ground.
USB IO Board

USB IO Board is a tiny spectacular little development board / parallel port replacement featuring PIC18F2455/PIC18F2550 microcontroller. USB IO Board is compatible with Windows / Mac OSX / Linux computers. When attached to Windows IO board will show up as RS232 COM port. You can control 16 individual microcontroller I/O pins by sending simple serial commands. USB IO Board is self-powered by USB port and can provide up to 500mA for electronic projects. USB IO Board is breadboard compatible.

ESR Meter / Transistor Tester Kit
Audiophile Headphone Amplifier Kit
ESR Meter / Capacitance / Inductance / Transistor Tester Kit

ESR Meter kit is an amazing multimeter that measures ESR values, capacitance (100pF - 20,000uF), inductance, resistance (0.1 Ohm - 20 MOhm), tests many different types of transistors such as NPN, PNP, FETs, MOSFETs, Thyristors, SCRs, Triacs and many types of diodes. It also analyzes transistor's characteristics such as voltage and gain. It is an irreplaceable tool for troubleshooting and repairing electronic equipment by determining performance and health of electrolytic capacitors. Unlike other ESR Meters that only measure ESR value this one measures capacitor's ESR value as well as its capacitance all at the same time.
Audiophile Headphone Amplifier Kit

Audiophile headphone amplifier kit includes high quality audio grade components such as Burr Brown OPA2134 opamp, ALPS volume control potentiometer, Ti TLE2426 rail splitter, Ultra-Low ESR 220uF/25V Panasonic FM filtering capacitors, High quality WIMA input and decoupling capacitors and Vishay Dale resistors. 8-DIP machined IC socket allows to swap OPA2134 with many other dual opamp chips such as OPA2132, OPA2227, OPA2228, dual OPA132, OPA627, etc. Headphone amplifier is small enough to fit in Altoids tin box, and thanks to low power consumption may be supplied from a single 9V battery.

Arduino Prototype Kit
RF Remote Control 433MHz Four Channel
Arduino Prototype Kit

Arduino Prototype is a spectacular development board fully compatible with Arduino Pro. It's breadboard compatible so it can be plugged into a breadboard for quick prototyping, and it has VCC & GND power pins available on both sides of PCB. It's small, power efficient, yet customizable through onboard 2 x 7 perfboard that can be used for connecting various sensors and connectors. Arduino Prototype uses all standard through-hole components for easy construction, two of which are hidden underneath IC socket. Board features 28-PIN DIP IC socket, user replaceable ATmega328 microcontroller flashed with Arduino bootloader, 16MHz crystal resonator and a reset switch. It has 14 digital input/output pins (0-13) of which 6 can be used as PWM outputs and 6 analog inputs (A0-A5). Arduino sketches are uploaded through any USB-Serial adapter connected to 6-PIN ICSP female header. Board is supplied by 2-5V voltage and may be powered by a battery such as Lithium Ion cell, two AA cells, external power supply or USB power adapter.
200m 4-Channel 433MHz Wireless RF Remote Control

Having the ability to control various appliances inside or outside of your house wirelessly is a huge convenience, and can make your life much easier and fun. RF remote control provides long range of up to 200m / 650ft and can find many uses for controlling different devices, and it works even through the walls. You can control lights, fans, AC system, computer, printer, amplifier, robots, garage door, security systems, motor-driven curtains, motorized window blinds, door locks, sprinklers, motorized projection screens and anything else you can think of.

Electronics-DIY.com © 2002-2024. All Rights Reserved.