Don’t buy an amp, build one to suit

In need of an amplifier for his home entertainment system [Afroman] decided to build an amp rather than buying one. If nothing else, doing it himself allowed for a form factor that can’t just go out and buy.

He designed the project on two separate boards, one for the power supply and the other for the amplifier circuit. Both are of his own design, and although he doesn’t share the schematic, we know he’s based his work on a National Semiconductor reference design for the LM4780 audio amplifier chip. There’s a few other clues, like his mention of the toroidal transformer seen at the left in the image above and hi-res photos of the unpopulated board that has component values printed in the silk screen.

The final design allows him to get great performance out of his speakers with a very clean look. You’ll need to be logged to the forum linked above to view all of the images, but we’ve embedded three more of them after the break to whet your appetite.

Oh, and cost? This gets up there, just sneaking past the $500 mark.

Continue reading “Don’t buy an amp, build one to suit”

More 555 Projects to Enjoy

We love all of the projects that are coming out for the 555 design contest, so we thought we would share a couple more that have caught our collective eye.  Have a 555 project of your own? Be sure to share it with us, and keep an eye out for the contest submission dates. Read on for a few of our project picks.

Continue reading “More 555 Projects to Enjoy”

Audio cabinet refit with modern equipment

Hard at work on making this 1960’s Fleetwood audio console usable again, [Travis] packed a lot of power into the retro case. Both the radio and turn table had stopped working but the cabinet looks great and the speakers still work. In the lower center cavity you’ll now find a full computer motherboard and replacement amplifier. A new turntable has been added with an interesting vibration-dampening shelf to support it. [Travis] built the shelf with a void in between two layers of wood which he filled with sand to help with isolation. The remote control for the amp also needed some work as the receiver is pointed to the back of the unit. To fix that a second IR receiver found a home behind the fabric for one of the speaker grates. That receiver is monitored by an ATmega168 microcontroller and signals are repeated back to an IR LED mounted near the amplifier.

1953 Radio includes tubes, AM, FM, and MP3

This vintage radio can play AM, FM, and MP3, all with a classic sound. Inside you’ll find a new AM radio tube-amp, providing the functionality you’d expect from the device. The rest of it comes from a conglomeration of parts; an FM receiver board from another radio and an MP3 player with remote control and USB connector. The classic sound we mentioned above comes from an AM modulator. That’s right, the auxiliary audio boards aren’t connected directly, but are broadcast on the AM band so that your latest MC Lars album has the same sound quality as the traffic report.

Check out this similar project from last year that adds RDS to a vintage radio.

Making mobile audio work at home

[Nikita] made a great find while cleaning out his garage: a set of audio amplifiers from a 1986 Volvo. After a bit of testing, he dislodged a stuck relay and set out to use these amps for a home audio system. He grabbed some left over brackets from his TV mount and used them as rail mounts. On the back he wired standard speaker connectors and RCA connectors to the wiring harness for the amplifiers. The final aspect is powering up the device, for which he used his ATX psu previously modified as a bench supply. 130-Watts of power for the cost of a few connectors.

We surprise to find we haven’t covered this common ATX bench-supply conversion before. What we have seen is an adapter to use one as a bench supply.

Audio breakout box for MacBook Pro

[Billy] wanted to use the audio connector on his MacBook Pro for input and output at the same time. He knew it could be done because Apple sells headphones with built-in microphones that work with the computer. He set out to build a breakout box so that he could connect the components of his choice to the single port. Using a scart-RCA adaptor box he scrapped the scart plug and wired the RCA jacks to the Apple headphone wires. He can now patch the pickup of his guitar to the mic connector, send it through the MacBook, and run the output back to his guitar amp.

VFD as a sound amplifier

[Alessandro Lambardi] had some vacuum flourescent displays that he pulled from junked VCRs. His latest project is an experiment to use one of the VFDs as a headphone amplifier (Wayback Machine Cache). This means he’s trying to use them as vacuum triode amplifiers, aka vacuum tubes. He did get it to work but as he suspected, the output is fairly low power. It may be possible to use this setup as a preamp and build an actual tube amp to use along with it.

Update: Thanks to [Fallen] for mentioning that we’ve covered this concept in the past.

[Thanks Muris]