I bought a very cheap USB dual channel Oscilloscope off ebay for £15 --- it only works DC 0 to +5v but can use standard x10 probes, the scan rate is fast enough for automotive sensors. It is ideal for checking Lambda sensor output and TPS.

Main draw back is the software is pretty limited not anything like as good as Picoscope but it works, and I have found it much more useful than the hand held scope I have. Ebay item 150556591171




They also do a 5 channel version that will measure AC voltages.

Oh forgot to say the USB lead that was supplied with mine was foobarred -- caused 10 minutes of cursing.

is it fast enough for checking crank sensor signals?

Postage is a bit OTT but at £21 overall seems like excellent value - according to the spec it seems fast enough for crank sensors - what is the screen like - is it a continuous line like a proper scope or is it bitty?

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Originally posted by v8kid
Postage is a bit OTT but at £21 overall seems like excellent value - according to the spec it seems fast enough for crank sensors - what is the screen like - is it a continuous line like a proper scope or is it bitty?

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5v maximum input looks a bit limiting.

In single channel mode an 8khz sample rate would be enough for most crank sensors at low engine speed, but e.g. a 36 tooth wheel at 6000 RPM has a fundamental of 3.6kHz, too high to get a reasonable waveform at 8kHz.

[Edited on 11/2/11 by MikeRJ]

5V but it is standard 1 megohm so can use a x10 probe

With sampling rates like that, you're probably better off using a x10 probe and your PC/laptop sound card inputs with some free software. Even the most basic sound card will give 44.1KHz sampling rate these days.

Alternatively, look at these (cheaper on eBay).

Ed.