LM3875 PDF

Folks: I have finished four LMbased amps using Brian Bell’s terrific PCBs and am thrilled with the result. But as I follow the various threads. LM OvertureTM Audio Power Amplifier Series High-Performance 56W Audio Power Amplifier. The is a high-performance audio power amplifier capable of. Gainclone amplifiers have VERY few components and this one is based on the National Semiconductor LM IC. The PCBs and components are very simple .

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My system has two kinds lm38875 equipment, those that stay on all the time and those that get turned on with a master switch. The case can be left floating or attached to the signal ground.

Even with the heat sink on top they get pretty warm if you work them hard. Generally, the lower the impedance of your speakers, the lower the voltage should be. The model Gaincard from 47 Laboratories is a 25 Watt stereo amplifier about the size of a video cassette, powered by a large external supply.

Last update 28 July I next tried bigger filters, but took them out in favor of the uF Panasonics that came with the kit. I settled on 20 volt secondaries which I think is a good compromise, feeling that 18v is perhaps a little too low and 22v a little too high to get the max with a 4 ohm load whilst minimising output loss if using 8 ohms. Rohit Balkishan Dubla Figure 1: I had a suitable transformer that didn’t make it into another project, so off we go.


The author grants the reader the permission to make at the most one 1 copy for personal use only. Figure 1 shows the amplifier schematic one channel only – two ICs are required for stereo. I preferred the two big bridges, which sounded more open and powerful, but clearly there is room to experiment.

If you have looked at the other projects on the site you will see that a modified K is my primary serious listening amp. A ferrite choke on the end of the power cord is used to reduce any stray EMI from going into the amp.

The circuit includes an auto ranging as well as reset switch and produces very accurate and stable readings. With the transformer and capacitors that I have used, the LM sounds as good as any other “standard” or discrete power amplifier. From stereophile Z in data. 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.

The next step was to get everything into the boxes.

LM3875 Gainclone Power Amplifier

The amplifier is fitted with an RSR plug to receive power from the remote supply. The actual layout of the circuit board could be something like this: It’s small, power ,m3875, yet customizable through onboard 2 x 7 perfboard that can be used for connecting various sensors and connectors.

Please note that I will be using the component numbering used here throughout this page, so refer back to this diagram as needed.

In short excellent, as the scope traces see photos demonstrate. In general, though, the capacitors affected the sound more than the resistors, the diodes more than the capacitors, and the transformer most of all. Created 16 December Carbon resistors are used throughout.


Mark and Gio had been after me to try a chipamp for some time. Moving magnet phono pre-amplifier – 1. They come with snap in jacks of all types. My original plan was to build a chipamp with a solid state or tube buffer. I will be making lm385 of these amplifiers simultaneously but with a few critical component differences.

Lm3875 TF 56w HIFI Audio Power Amplifier IC LM3875TF

Power cord is captive four pin molex, one per channel. So I went ahead and built a chip amp without the buffer. One is based on standard components, and one on premium components. It had flat response from DC to kHz.

RJM Audio – LM Non-inverting Gainclone

If you do it right the amplifier is completely quiet but grounding can be a problem. All wiring is similar to this point-to-point LM gainclone using a breadboard. I actually bought the parts. A modest heat sink stuck on a piece of tin, ,m3875 tacky.

That lm38875, a single integrated circuit based lm375 an operational amplifier op amp on a single substrate of silicon. From the 47 Labs website: Arduino Prototype uses all standard through-hole components for easy construction, two of which are hidden underneath IC socket. I followed the Gaincard pretty closely in using the mute switches, the attenuator, and choosing to have the same gain and input impedance.

The circuit is based on the typical application given in the datasheet but with a few changes as follows: I would lmm3875 VA as the absolute minimum transformer rating for stereo operation, with VA being a good compromise between cost and performance.


R4 is soldered directly between the leads of the IC, which is itself tucked underneath the board together with R2 and R5. I hate working in tight spaces but I am pretty good at it.

Headphone amplifier is small enough to fit in Altoids tin box, and thanks to low power consumption lm3857 be supplied from a single 9V battery. It easily surpasses everything I’ve owned except for my modified K Tube Amp kit.