Category Archives: Electronics

Bose® Active Equalizer Test Platform

Posted on April 13, 2016 by retrovoltage

Looking for the latest info on repairing your Bose 901 Series I, Series II, or Bose 800 Active Equalizer and speaker system? Take a look at the latest in-depth guide with everything you need to know (and more!) This project … Continue reading →

Posted in Audio, Bose, DIY, Electronics, Stereo, Test Equipment | Tagged , , , , , | 3 Comments

“Won’t that ruin the vintage sound?”

Posted on March 16, 2016 by retrovoltage

Audio as a hobby sits in an interesting place in the world. There are hard numbers and objective measurements made with lab equipment on one end, and on the other end you have the subjective and variable linguistic descriptions assigned … Continue reading →

Posted in Audio, Commentary, Electronics, Hi-Fi, Vintage | Tagged , , , , , , , | 3 Comments

Building the SSTRAN Part 15 Low Power AM Transmitter Kit

Posted on February 21, 2016 by retrovoltage

Have a bunch of old tube radios, but nothing good on the air in your area? That’s a common problem, and SSTRAN has the solution! I just built one of these to give as a gift, and thought I’d write up … Continue reading →

Posted in DIY, Electronics, Projects, Radio | Tagged , , , , | 3 Comments

Retro 1956 Cyclometer VTVM – Hycon Model 615

Posted on February 19, 2016 by retrovoltage

A pretty cool, very rare piece of test equipment turned up on eBay recently: a 1956 Hycon model 615 AC/DC VTVM. This was a precursor of today’s digital, using analog servo circuitry to drive the numeric digit display. These were … Continue reading →

Posted in Electronics, Gadgets, Test Equipment, Vintage | Tagged , , , , , | 2 Comments

Building a Better Voltage Regulator

Posted on February 17, 2016 by retrovoltage

Glancing through my feeds, I stumbled across a note on The Paleotechnologist describing a new replacement for the venerable LM7805 linear regulator IC. It turns up in a ton of devices, pretty much anything with a medium-current 5V rail including … Continue reading →

Posted in Collections, DIY, Electronics | Tagged , , , , , , , , , , | Leave a comment

How to Read Capacitor Codes

Posted on January 24, 2016 by retrovoltage

I ended up with a massive stash of mil-spec CDE Mica caps recently, and was searching for a refresher on decoding their military part numbers like “CM05FD221GP3”, since the caps came marked for their values but not their voltage ratings. … Continue reading →

Posted in Commentary, DIY, Electronics | Tagged , | 1 Comment

Philips High Fidelity Laboratories 673 Tuner Repair and Alignment

Posted on January 4, 2016 by retrovoltage

This Philips 673 tuner just came through the shop for an overhaul and adjustment. It was working for the most part but the alignment had shifted and there was room for improvement on the sound quality. Philips designed this tuner … Continue reading →

Posted in Audio, Electronics, Radio, Vintage | Tagged , , , | 3 Comments

HH Scott 233 Stereo Integrated Amplifier Overhaul

Posted on December 31, 2015 by retrovoltage

I was lucky enough to get to work on a very nice Scott 233 stereo integrated amplifier. This example was wonderfully well preserved, coming out of a storage unit looking like it had just left the showroom floor. Unfortunately, though, … Continue reading →

Posted in Audio, Electronics, Radios and Tubes, Stereo, Vintage | Tagged , , , , , , | 7 Comments

What do we have here?

Posted on December 1, 2015 by retrovoltage

I was reading about how to build a capacitor checker from the December 1959 issue of Popular Electronics and stumbled across something that looked very familiar. I know that shape. Nearly identical to a Bose® 901 Series I/II cabinet, and even … Continue reading →

Posted in Audio, Bose, Collections, Commentary, DIY, Electronics, Vintage | Tagged , , , , , , , , , , , , , | 2 Comments

Bose® 402E Active Equalizer #102853 Repaired

Posted on November 30, 2015 by retrovoltage

The first Bose® 402E Active Equalizer, for the Panaray speaker system, just came through the shop. It’s a small speaker array system, designed around similar drivers in the 901, and uses an Active Equalizer for the same effect. They’re designed … Continue reading →

Posted in Audio, Bose, Electronics, Projects | Tagged , , , , , , , , | 7 Comments