In this tutorial Dave describes what AC trigger coupling is on an oscilloscope and why it can be useful. Not only on old analog CRT oscilloscopes, but modern digital scopes as well.
How and why is it different to AC channel input coupling?
Also, use of the 50% trigger control, and how the venerable DS1052E is still more usable than the new DS1054Z.
EEVblog #685 – What Is Oscilloscope AC Trigger Coupling? - [Link]
by Dave Rishavy @ edn.com:
Noise on a signal creates a triggering challenge for test equipment, especially oscilloscopes. Because the instrument itself also contributes noise, small signals in the millivolt range need proper instrument settings prevent noise from overwhelming the signal of interest. Even with larger-amplitude signals, noise can create a condition where a stable trigger is difficult to achieve.
Oscilloscope have built-in features to help deal with the noise. These features can sometimes be buried in menus, or not well known by infrequent oscilloscope users.
View noisy signals with a stable oscilloscope trigger - [Link]
Viktor made a sound trigger for his DSLR camera:
Now that I can take pictures of lightning I decided that I also want to be able to trigger my camera with sound.
An op-amp filters and amplifies a microphone signal. The output is fed to a PIC microcontroller that triggers the flash when the sound reaches a certain level. The trigger sound level and shutter delay are set with a pot. [via]
Lil Bang – Sound trigger for cameras - [Link]
David L. Jones writes:
One of the more obscure controls on an oscilloscope is the Trigger Holdoff control. A dedicated control on most high end analog oscilloscopes, and a main menu option in modern digital scopes, yet often poorly understood. What does it do and how does it work?
Oscilloscope Trigger Holdoff Tutorial – [Link]
The SPOT is a device that lets you adjust and trigger off-camera flashes remotely. It’s an essential tool for using artificial light. The creative possibilities that off-camera flash provides are endless. The SPOT has two modes of operation:
– As a transmitter it sits on the hot shoe of a camera and forwards electrical flash trigger signals from the camera to slave flashes via radio
– As a receiver it is connected to a small hot shoe (?system?) flash
Strobist Project Opensource Trigger – [Link]
This project shows how to build a sensor to trigger a camera’s flash using a microphone or laser pointer. The brain of the project is an Arduino and it will activate the flash at accurate timing to capture precise moments. You can easily add new sensors, or even run multiple sensors at once. Since the triggering of the flash is done in software it’s easy to add delays, or make a more complicated triggering algorithm based on multiple sensors.
Triggering a Camera’s Flash with Sound and Light – [Link]
Nicholas Skinner has build a doorbell control project that adds some advanced features over a simple door bell. It has three main features: it allows triggering other devices on press, it has a bell ring disable ability and allowing the bell to keep ringing for a certain minimum duration. Check details on this project on the link below. [via]
Doorbell Control with the Synapse RF Engine – [Link]
This instructable shows you how to add a time lapse module to a Rollei Compactline 52 digital camera. The idea could also be implemented for other point and shoot cameras. The device is able to power on the camera, take a photo and then shut the camera down. In this way the battery will last plenty of time. It is based on ATtiny24 and length of time between shots can be configured. It also has the feature to automatically shut down when it gets too dark outside. Check schematic and board files on the link below. [via]
Timelapse circuit for point and shoot cameras - [Link]
This project shows how to build a synchronization box capable to control up to four external flashes. External flashes are connected using RCA connectors. It is able to connect to a camera or other triggering sources like a sound trigger for example. Check schematic on the link below. [via]
DIY multi flash syncronization - [Link]