SCOPE: Eurorack oscilloscope interface module (4HP)
Oscilloscopes are useful for debugging builds, and they're even more useful if you can hook your modules up to them with a minimum of fuss - which is where this module comes in.
Since I have a dual-channel 'scope I decided to build a dual-channel interface module to help me diagnose build issues - and here it is. It's fairly simple - two channels consisting of a resistively-coupled 3.5mm input connected via an op-amp buffer to a BNC output, thus allowing you to hook one end up to your 'scope and plug modules into the other end with a minimum of fuss.
Simple, yet effective (in other words, It Works For Me)
The module is fitted with a pair of female BNC connectors, one per channel - most 'scope test leads are F-F but for those which aren't there's a pair of M-M BNC couplers included.
The buffering op-amp doesn't go rail-to-rail, so any signals over +/-10V are likely to be clipped. If you're handy with a soldering iron and are confident with surface-mount componentry then you can easily replace the op-amp.
The module is supplied with a 4HP panel fabricated from 1.6mm FR4 fibreglass (aka PCB material). Mounting hardware and a power cable are also included.
Current consumption is typically less than 10mA on both +12 and -12V - the only active component on board is a dual op-amp which buffers the two signal inputs.
IMPORTANT: this module was designed for use with audio frequency signals (up to around 20kHz) - whilst there's nothing to stop you using it for RF or other high-frequency work, you may find that the results are suboptimal. To reduce noise, make sure that whatever supply you connect the module to is well grounded.