Audio on PCB Isolation

Repairing and Adding Bluetooth to an 80’s – 90’s AC Delco Radio

Wed, 17 Jun 2020 00:00:00 +0000

AC Delco Model 16131355

This post details the repair of a early 1991 AC Delco stereo. AC Delco made many variants of this stereo for both Chevrolet and GM cars, trucks, and vans from the early 80’s to the mid-90’s. While many of the stereos have more or less features (cassette players, radio presets, etc), the amplifier section of the radio is fairly standard and unchanged.

Internal Pinout and Schematic

TDK Trek Max A34 Teardown

Tue, 04 Apr 2017 00:00:00 +0000

This is a great bluetooth speaker - loud, good sound quality, waterproof, and durable. Yet sometimes it has bluetooth problems, playback problems, and doesn’t work when in motion (like in a backpack).

I opened this up to look for issues. I found none. Note that you are removing glued pieces and may lose some waterproofing. Mine still seems very water resistant, but I wouldn’t dunk it in a lake.

Simple Automatic Volume Control with Arduino

Tue, 20 Sep 2016 00:00:00 +0000

This was for a pair of outdoor speakers in front of KMNR, my college radio station. KMNR was receiving complaints for having the music too loud at night.

An Arduino checks clock and adjusts volume using digital potentiometers This post is a walkthrough of the design and implementation.

Design

I interfaced an Arduino with a RTC (real time clock) to get the time. The RTC is Maxim’s DS1307 and it should last 17 years on it’s backup battery. It communicates over I2C and you can find already written code here.

LED Sound Reactor – All Analog Approach

Fri, 02 Sep 2016 00:00:00 +0000

In the winter of 2013, LED strip lighting hit its tipping point - a big rise in popularity.

A year beforehand, in 2012, I had an idea to build a controller for LED strip lighting. A sound reactive LED controller

to make the lights get brighter on the bass notes. Biggest problem - I didn’t know how to make one.

I finally started getting comfortable with electronics in 2014.

2×15″ Home Subwoofers, Car Amp, & Server Power Supply

Thu, 23 Oct 2014 00:00:00 +0000

After half a semester of college, I learned that my 8″, 40W woofer wasn’t enough. I wanted something bigger, but didn’t want to have to upgrade again in the future. So I decided on something reasonable for any 10’x15′ dorm room - two 15″ subwoofers powered by a 1000W car amp. My goals: keep it under $400, design it so one of the two subs can be placed in a car and be powered from a 12V source (like a car battery), and build them to be as durable as possible.

Logitech Z340 2.1 Pinout and Reuse

Sun, 08 Jun 2014 00:00:00 +0000

Logitech has a large presence in 2.1 systems, where price and appearance dominate. This sub is designed to trick you, there’s more to it than what meets the eye.

I picked up a used Logitech Z340 2.1, sans the 2. I got a woofer with no satellites or volume control.

notice in the corner - Mr. Happy Hammer 🙂

8″ subwoofer (4″ speaker + cardboard)

Since I don’t have the satellites, this is of no value to me. And the speaker isn’t of much value either, so I want the amplifier out of this.

Mazda 2 Quickest Subwoofer Installation Ever

Thu, 05 Jun 2014 00:00:00 +0000

Running wire, head unit adapters, fuses, and less trunk space all suck. Let’s not do that. Modular setups seem more promising.

A few months ago, I assembled a $6 tube subwoofer that could be used in a house or in a car. I only recently set up my car for this sub. It took an hour. No new head unit required.

There’s only one real compromise to this, only the audio coming from the auxiliary port is sent to the sub. That’s how I listen to music 95% of the time, so no subwoofer with the CD player or radio is fine for me. I tapped into the auxiliary output right next to the cigarette lighter, so I ran power from there. The cigarette lighter is only on when the car is on, so I don’t have to worry about draining the battery when the car is off. There are no power supply issues, as the cigarette lighter supplies 20A, while the sub only draws 4A max.

Powered Subwoofer for Your Car and House

Sun, 05 Jan 2014 00:00:00 +0000

I have a thing for subwoofers, convenience, and low cost. Arguing over DVCs in $300 subs isn’t my thing.

This 8-inch tube subwoofer was $1 a garage sale.

Tube subs are popular for their size and portability, you can set it in a car trunk or behind a truck seat with no thought or effort. The enclosure is plastic so they are lightweight. To reclaim trunk space, pull it out.

Powered Subwoofer & Box Build

Sun, 17 Feb 2013 00:00:00 +0000

Kicker’s Free Airs left a legacy in the market. They have almost no enclosure requirements and are often drop-in upgrades.

I picked up two used 6.5″ Kicker Free Air subwoofers. “Free Air” is a misnomer, they still need an enclosure. However the enclosure space can be relatively large. The trunk of your car could be considered an enclosure, as long as the space in front of these speaker is sealed off from the space behind these speakers. I don’t plan to put these in a car, they are going to be for a home sound system. I like the early 2000’s sub look that these Kickers have: thickly stitched cones, paint chipped rusting frame, rotting seal, and corroded leads. At one point they were very nice, now they are fair. I can deal with fair speakers if they are free.