The Gainclone. Introduction: Background Info: Construction Notes. Introduction. The model Gaincard from 47 Laboratories is a 25 Watt stereo amplifier. Check for Samples: LM The LM is a high-performance audio power LM to reduce the effects of PCB trace resistance and inductance. PCB for 56W Audio Amplifier using LM HiFi Amp. For LM IC. High quality FR4 double-sided, plated-thru and tinned holes, with conformal coating.

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There are no dedicated heat sinks here because the entire aluminium chassis, which houses the amplifier, serves as a heat sink Figure 7. In short, no excuses.

This gives the stated nine part circuit. Is lm875 as a supply voltage to the IC power supply or amplifier circuit. The volume potentiometer can be implemented as a standard potentiometer or, as in this case, stepped attenuator. In the years since this started, power op-amps have become a major part of the DIY scene with dozens of different circuits and hundreds if not thousands of builders worldwide.

Leave a Reply Cancel reply. An example of a circuit that could do this would be using a Texas Instruments DRV chip to invert one of the two non-inverted amplifiers.

Gainclone LM PCB – Electronics Projects Circuits

LevHyp 19 May Reply. It is a standard non-inverting circuit, where the output signal is in phase with the input signal. I tried both Shottky and ultrafast types, rated 3 or 5 amps. Both boards will be wired in parallel mode, and then the input to one of them will be inverted for more power. This schematic is for half of the board only. The voltage gain of the chipamp is determined by resistors R3 and RF, according to the following equation: Four FE5D diodes are used for rectification.


Dual bridge rectifiers as shown above. Generally, the lower the impedance of your speakers, the lower the voltage should be. This result is shown below: Note that C1 must be non-polar. Power supply parts list: The National Semiconductor’s Overture series of integrated circuit IC audio amplifiers owes its rise to ‘fame and glory’ to a relatively big success of the 47 Laboratory’s Gaincard amplifier, based on the LM chip from the National Semiconductor.

To bypass the capacitors, just run a jumper for each of them. From stereophile Z in data. As a result, you will need to use four amplifiers two boards per speaker and a circuit capable of inverting the signal to one of the amplifier pairs.

In Figure 3 This project is non inverting amplifier circuit. The board also has a spot for a 22uf non polarized capacitor between R4 and ground.

Both the amplifier and external power supply were cased in Hammond series cast aluminum boxes.

RJM Audio – LM Non-inverting Gainclone

This will provide W into each speaker. There are some little further: You can use a linear power supply to take at next level this circuit. In general, though, the capacitors affected the sound more than the resistors, the diodes more than the capacitors, and the transformer most of all.

Also, the concept is so minimalist that it leaves very little room for major mistakes so you lk3875 be able to freely indulge in fearless experimentation with different values and brands of capacitors, resistors, etc. Star-grounding will help you to avoid ground loops, which may lead to severe problems with hum and noise in audio amplifiers. All the capacitors and R3 are on the top side.


Power cord is captive four pin molex, one per channel. The input impedance of the amplifier is determined by resistor R1. So it is almost a complete IC without lm387 circuitry, thus leading to yet more user-friendly and convenient.

However, if you may ever have the amplifier powered on but disconnected from the input source, it is reccomended that you use this capacitor. The chips should be well heatsinked, but electrically isolated from the heatsink.

The transformer should be rated to around VA and be either a torroid, R-core or C-core type with cpb secondary windings of 16 VAC. Quote and Order boards in minutes on https: I can’t comment on sound quality in parallel mode, because I only wanted to use that mode to try and run a 4 ohm subwoofer speaker.

LM3875 Gain Clone Amplifier Project

This is all explained further down. This image is to be used as a guide while assembling. The use or copying of the contents of this page, in whole or in part, for any commercial purpose is expressly prohibited. Mute switch is a mechanical switch of the output. However, ,m3875 you decide that you wish to squeeze more power from the amplifier, you will surely need better cooling.