LM3875 PDF

December 7, 2018

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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A look at the images reveals just how small this amp is. The output waveforms can be both amplitude and frequency modulated. Thank you National Semiconductor for saving me from myself.

Still the basic set lj3875 was rather utilitarian, I wanted a distinctive look.

LM Gainclone Power Amplifier

The chips should be well heatsinked, but electrically isolated from the heatsink. 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 lm387 4 ohm load whilst minimising output loss if using 8 ohms.

Lights, switches and wiring can be sources of noise and hum and I hate hum. For the first few hours it was kind of bright really it was too bright for my tastes.

This LC Meter allows om3875 measure incredibly small inductances making it perfect tool for making all types of RF coils and inductors. 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 too grainy, and from a different circuit metal film too, uh, metallic and zingy.

I had plenty of small enclosures but nothing big enough.


Lm3875 TF 56w HIFI Audio Power Amplifier IC LM3875TF

There was a sort of marriage of parts. It had a good sound stage, no noise.

The chipamp was easy as there are almost no parts. The case can be left floating or attached to the signal ground. The schematic for The Nanoo is lm38775 below in Figure It cooked lm3857 several days as I forgot to turn it off. To maximise thermal transfer between the IC and the heat-sink, the insulating mica washer may be omitted. Now back to the amp. The meter is a perfect addition to any power supply, battery chargers and other electronic projects where voltage and current must be monitored.

Not in the same class as the LM monoblock amplifiers but extremely listenable. The box size is X 94 X 34 mm.

I had no idea a better amp would make a such a big difference to my system. To make both parts look alike I used two plastic project boxes from Radio Shack. Testing the assembled amps on a desk. The meter is a perfect addition to any power supply, battery chargers and other electronic projects where voltage and current must be monitored.

That way I have no preconceived ideas about how something should sound based on the measurements. This result is shown below:.

A VA torroid with 2x 12 V secondaries and electrostatic screen from Plitron supplied the power. The only thing that might trip someone up is that it is a good idea to use heat sink grease between the chips and whatever you use to absorb the heat.

DIY LM3875 Chip Amplifier (Gainclone) Kit

It came from an odd place. This great chip, is a little larger than the size of a thumbnail and can deliver up to 56W RMS continuous with W peaks and it can do lmm3875 at 0. It looked cool sitting on tall feet, unfortunately llm3875 didn’t run cool. DC offset was about 80mV ,m3875 one channel and about 40mV on the other.

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I bought all the aluminium from a scrap metal yard including the heatsink. 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. The chips are bolted to the sides of the case so cooling is not optimal.

The only area the K beats the Beauty and Beast is in midrange detail and sound stage. For R1 and R5 I’m not sure.

Nanoo – DIY LM IC Non-Inverting Chip Amplifier (Gainclone)

Signal to noise is extreme. Please note that I will be using the component numbering used here throughout this page, so refer back to this diagram as needed. The circuit includes an auto ranging as well as reset switch and produces very accurate and stable readings.

You see, I don’t lm375 line switches or power indicators in anything unless it is absolutely necessary. C2 is most likely also omitted.

I use it as my family room amp driving two 63L 12″ woofer based 3-way system. Arduino Prototype uses all standard through-hole lm38755 for easy construction, two of which are hidden underneath IC socket. I did run into a problem during assembly though. The following is a suggested layout-schematic for the power supply: The first version fortunately no photo as it would be just too embarrassing was a collection of parts sprawled on a shelf with the rest of my gear.

Measurements are helpful to refine, but I allow my ears to be the final judge on any changes. For stereo operation, the transformer may be rated between VA to VA.