The Crash Sync is a John Hollis design who’s schematic can be found here. There are dozens of examples of these on the web. They’re pretty popular among DIY enthusiasts and not terribly difficult to throw together. John’s site has a number of great projects that center around Op Amps and are very affordable to complete.
I typically use whatever components I have available, either bought or raided from old gear, so when putting a project together there are some inevitable changes. In this project I used different Op Amps and added in a bypass switch (with lights of course) to pass the original signal. As far as I can tell using a different op amp hasn’t had a noticeable impact on the sound of this awesome little box. Lastly, like all of my boxes so far, I haven’t wired them up for use with a 9V… which is fine for me, but others might find it an inconvenience. See the full flickr set for detailed photos.
Many more photos and comments on this build can be found on Flickr here: