spasticteapot
Newbie level 2
lm3875 pcb
To be quite honest, I'm rather new to electronic design. I'm in high school, and have limited access to help, so I figure I'd be best off asking on a public forum.
I'm looking to build a LM3875-based amplifier using inexpensive, high-precision components. I'm using primarily Vishay/Dale metal-film resistors, because they're cheap and availible from Mouser, in addition to having a 1% tolerance on most of the parts.
I've designed the following double-sided PCB. It's quite small, and is designed to be; a lot of sound quality loss (yes, it's an audio amplifier) is due to long, messy traces. Also, a 33$ dual-sided PCB from Olimex would get me 12, not a bad deal at all.
On the left side, you should see -, G, +, OG, and O. "-," "G," and "+" are the power supply inputs; I have an unregulated 300w PSU for powering the two amplifier modules with a large number of capacitors on them. "OG" is the output ground, and "O" is the output to the speaker. (Yes, the speaker ground and power ground are connected).
On the right are E$1 and E$2. E$1 is the input, and E$2 is the input ground. From what I've heard, a long, thin PCB trace connected to the "star" ground is a good idea; however, these people also have complicated recipies for speaker varnish, so I take everything they say with a grain of salt.
The capacitors are 100uf, but there are also 2 12,000UF capacitors on each side of the power ground for the power supply. This should be plenty for two ~30w amplifiers.
Thoughts?
To be quite honest, I'm rather new to electronic design. I'm in high school, and have limited access to help, so I figure I'd be best off asking on a public forum.
I'm looking to build a LM3875-based amplifier using inexpensive, high-precision components. I'm using primarily Vishay/Dale metal-film resistors, because they're cheap and availible from Mouser, in addition to having a 1% tolerance on most of the parts.
I've designed the following double-sided PCB. It's quite small, and is designed to be; a lot of sound quality loss (yes, it's an audio amplifier) is due to long, messy traces. Also, a 33$ dual-sided PCB from Olimex would get me 12, not a bad deal at all.
On the left side, you should see -, G, +, OG, and O. "-," "G," and "+" are the power supply inputs; I have an unregulated 300w PSU for powering the two amplifier modules with a large number of capacitors on them. "OG" is the output ground, and "O" is the output to the speaker. (Yes, the speaker ground and power ground are connected).
On the right are E$1 and E$2. E$1 is the input, and E$2 is the input ground. From what I've heard, a long, thin PCB trace connected to the "star" ground is a good idea; however, these people also have complicated recipies for speaker varnish, so I take everything they say with a grain of salt.
The capacitors are 100uf, but there are also 2 12,000UF capacitors on each side of the power ground for the power supply. This should be plenty for two ~30w amplifiers.
Thoughts?
