Published by on August 21, 2021
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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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Salim Khan 22 May Reply. It is a standard non-inverting circuit, where the pxb signal is in phase with the input signal. I also compared it with a W x 6 home theater amp, and the home theater amp in stereo modewas able to reach higher volume without distortion, but they were very close in sound quality.

The sound is excellent, by far the best I’ve heard from a chip amp. Please download the freeware version of Eagle Layout editor from here to view any pcb file on this website.

Can be up-graded into a pair of complete mono amplifiers by adding another Model Power Humpty. It may look ugly at first, but its really very smart and compact. Capacitors C1 to C4 l,3875 used for the filtration of the ripple voltage from the rectifier. For only 56W, the sound is, as I’ve said, fantastic, and sounds like much more than 56W.

LM – Power amp kit

However, if you may ever have the amplifier powered on but disconnected from the input source, it is reccomended that you use this capacitor. This circuit is very good for a small hifi system in house, with medium overall specifications. Learn how your comment data is processed. Sound signal is amplified and then come out the pin 3 of IC.

LM Gainclone Amplifier Indroduction: The power supply consists of a transformer with two independent secondary windings and two full-wave rectifiers that supply power to both amplifier channels. It is not a bad idea to add a switch on the rear of the amplifier, whereby the star i. However, if your amplifier has a volume control potentiometer, as this one does, the resistor can be omitted.


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. It is understood that Kimura removed the film bypass caps C3 and C4, and R1 on lm375 circuit will be replaced by the stepped attenuator.

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

Most devices within the IC almost all. pdb

RJM Audio – LM Non-inverting Gainclone

The use or copying of the contents of this page, in whole or in part, for any commercial purpose is expressly prohibited. The actual layout of the circuit board could be something like this: Increasing power output into an 8-ohm speaker is trickier.

For a given capacitance, a lower voltage power supply gives a softer, more relaxed sound. If your input source is always connected, or you use a preamp, they are unneccesary, and I reccomend bypassing them with a jumper to have as little unneccesary parts as possible in the signal path.

There is a way around this, though, involving using two chips per speaker. You may wish to start with the power supply and grounding wires first and pay extra special attention to the high-voltage! I conclude from my experiences that carbon film is the right choice for the R2-R4, AB carbon composition sounded too noisy and fuzzy, metal oxide lm38875 grainy, and from a different circuit metal film too, uh, metallic and zingy.


LM3875 Gain Clone Amplifier Project

When the amplifier is bridged to increase power output to W into 8-ohm speaker, the load each amplifier “sees” is 4-ohm, which the LM is not capable of powering.

To bypass the capacitors, just run a jumper for each of them.

I never got the combination to work cleanly. The PCB file is avaliable in Eagle format, ready to print.


This article focuses on a tried and true low-power amplifier 30W with the IC LM, originally intended for the design and testing of active speaker systems. Figure 4 the PCB layout. Top Background Information Some things we know for sure: All circuit grounds should meet at only one point i. Figure 2 Figure 3 Figure 4 The amplifier can be used in the inverting mode, as well. After comparing a 4.

The signal into the ultra sonic filter circuit, which include of capacitor C3 and resistor R3 and R1 To act to prevent the radio noise signal and attenuate RF signal is lower, before the signal will into pin 7 thus this have high gain up to 25 times. Resistor R4 at the output of the amplifier improves stability and, in parallel circuits, helps to split the load between two amplifiers.

This will provide 25 wpc with LMs. Lj3875 gives the stated nine part circuit. However, if you decide that you wish to squeeze more power from the amplifier, you will surely need better cooling.

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