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.
| Author: | Nigor Tumi |
| Country: | Malaysia |
| Language: | English (Spanish) |
| Genre: | Business |
| Published (Last): | 25 February 2005 |
| Pages: | 53 |
| PDF File Size: | 20.38 Mb |
| ePub File Size: | 1.41 Mb |
| ISBN: | 691-7-43843-748-4 |
| Downloads: | 2186 |
| Price: | Free* [*Free Regsitration Required] |
| Uploader: | Gujinn |
You wire the two boards using the parallel mode schematic.
If your speakers pcbb 8-ohm, you only need one pcb for both speakers, with a power output of 50W per speaker. I never got the combination to work cleanly.
Learn how your comment data is processed. Furthermore, diodes D1, D3, D6 and D8 should then be omitted. Both the amplifier and external power supply were cased in Hammond series cast aluminum boxes.
Figure 3 the schematic diagram. In short, no excuses. The capacitor C5 is connected to R6 help lower frequency to -3dB at frequency about 10Hz. This requires cpb boards 4 amplifiers per speaker, plus a DRV board. Figure 2 Figure 3 Figure 4 The amplifier can be used in the inverting mode, as well. Separate power supplies can be used for each channel if desired. This circuit is very good for a small hifi system in house, with medium overall specifications.
The volume potentiometer can be implemented as a standard potentiometer or, as in this case, stepped attenuator. This projects have the Frequency response and the total harmonic distortion: Figure 1 The amplifier schematic is shown in Figure 1. The case can be left floating or attached to the signal ground. Power cord is captive four pin molex, one per channel. An extremely low parts count also allowed for a very compact and customizable design, as evidenced by numerous websites, fora and blogs dedicated to audio DIY and Gaincard clones aptly named ‘gainclones’ or ‘chipamps’.
It is also possible to use a transformer with a center-tapped secondary winding. Star-grounding will help you to avoid ground loops, which may lead to severe problems with pch and noise in audio amplifiers.
LM – Power amp kit
A 50 kOhm volume potentiometer could be substituted. In general, though, the capacitors affected the sound more than the resistors, the diodes more than the capacitors, and the transformer most of all. Therefore, you would want to choose an R3 value greater than 4. Due to the simplicity of the Gaincard design and construction, availability of inexpensive parts, as well as excellent value for money in terms of its quality and power, it soon became very popular and highly regarded among audio DIY hobbyists do-it-yourselfers or DIYers.
This chip delivers unbelievable quality, especially for it’s low power levels. However, if you decide that you wish to squeeze more power from the amplifier, you will surely need better cooling. Undistorted volume levels were also much better.
Here is how to wire the board for 4-ohm speakers: Figure 4 the PCB layout. Figure 6 Figure 7 This project is simple to build and requires only basic knowledge of electronics, especially if prefabricated commercially available PCBs with silk screens are used.
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. This is all explained further down. The PCB file is avaliable in Eagle format, ready to print. The transformer should be rated to around VA and be either a torroid, R-core or C-core type with dual secondary windings of 16 VAC. 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.
This amplifier is compact, looks great, sounds great, has a few dozen clean watts per channel, and dissipates only 2. All the capacitors and R3 are on the top side. The wiring is done like this: I tried both Shottky and ultrafast types, rated 3 or 5 amps. Construction Notes Introduction 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.
C1 should be included to protect your speakers but can be omitted if you know your source components are not DC coupled at the output. Rather than connecting the ground to a speaker, you take the positive output of the resistors from one amp and connect them to each side of the speaker.
Gainclone LM3875 PCB
The amplifier schematic is shown in Figure 1. Attenuator is ladder type. It is understood that Kimura removed the film bypass caps C3 and C4, and R1 on the circuit will be replaced by the stepped attenuator.
From the 47 Labs website: I compared a few different amps. Please note that I will be using the component numbering used here throughout this page, so refer back to this diagram as needed. Before leaving Speaker shall pass to the zobel network circuit that include of R4 and C4 To solve the problem with the load capacity and maintain stability at high frequency. You can also quadruple the power into an 8-ohm speaker. R4 is soldered directly between the leads of the IC, which is itself tucked underneath the board together with R2 and R5.
The voltage gain of the chipamp is determined by resistors R3 and RF, according to the following equation: The power supply consists of a transformer with two independent secondary windings and two full-wave rectifiers that supply power to both amplifier channels. The sound is excellent, by far the best I’ve heard from a chip amp.