开云体育

Currently eBay is showing 1804a 4 channel plugins for around $20-50. The 1804 does 4 channels but no math. The 2 channel units have addition and the specs say when one Chanel is inverted it acts like a differential input instrument! The 1821 dual time base is spectacular. It can be set up to have a variable width time delayed window within the display which is higher intensity on the screen and thus can magnify a signal within the signal. Also, a trigger can be set within that segment and a separate external trigger can be use for the main and the delayed segment. This gets you behavior like on a digital storage scope. Imaging the ability to trigger on certain glitches during the delay time. I used to use it to pluck out separate scan lines in an NTSC composite signal. Set up a separate circuit to count pulses in the signal and feed the counter output into the secondary trigger and you could pick the scan line. This is very flexible triggering.? Fun to use scope. I just picked up a 4 channel plug in and now have a 4 channel analog scope.? Screen display is rock solid when you get the trigger set up. The scope is intuitive to use. Schematics available. I think it is a great beginner scope if working. It is easy to repair with all discreet components. It has a cool feature of a signal delay line so you can see a bit of the signal before the trigger fires.