Cheapo Digital Scope

[tubesornothing]

http://www.dealextreme.com/details.dx/sku.39753

2.8" screen
Digital upload of pictures to your computer

$77

[sluckey]

Might want to keep that dude out of a tube amp.

[tubesornothing]

It'd be a nice way to watch $70 go up in smoke...  I expect there is not much isolation.

[PRR]

> Might want to keep that dude out of a tube amp.

It is a stunningly interesting input.

It runs on +/-5V but will eat 40V peak inputs.

The raw input goes to two small caps and a 510K series resistor. A plain old 4051 shunts various resistors to attenuate the signal. If set right, the voltage on the 4051 is never near its rails. If set wrong, the 4051's protection will survive hundreds of volts through that 510K resistor.

Here is another vendor, different version, and a manual:
http://www.elechouse.com/elechouse/index.php?main_page=product_info&products_id=396

The probe connector is non-standard.

The input impedance is non-standard and variable (513K to 1.02Meg). An "X10" probe is not a simple series resistor and some caps.

There are a bazillion and three things you can do with a scope under 40V peak.

Yeah yeah, anybody here wants to see a 1Meg 600V input, direct or with a simple probe. And AC coupling.

Plagiarize, plagiarize, plagiarize!



The need to balance capacitances is annoying. Most folk won't have the instrumentation to do this well. It does not have to be real perfect for guitar. However I am wondering if an inverting connection with 1Meg in and 1Meg 100K 10K 1K feedback would make capacitance effects negligible-enough?