I watched the video below and it made me think two things:
1. It's probably about time I got an oscilloscopeWhat is worth getting? I don't mind spending on quality, but I don't want to sink a lot of cash into features I may never use. What's a good budget buy, preferably something compact? Any pitfalls to avoid if buying used?
I have an old XP laptop sat doing nothing, so a gadget that would work with simple PC software would also be an option.
2. I wonder whether my Princeton Reverb rebuild could be subject to oscillation?I followed the original circuit (no grid resistors on the 6V6 valves), whereas the '68 Custom had 1.5k grid resistors. It would be an easy job to add them so I may as well do it anyway. Obviously if I have a problem, an oscilloscope will tell me!
Full disclosure: I have one of those little £18 pocket oscilloscopes off eBay but unsurprisingly, it's shit!
Comments
@SlopeSoarer I think that’s pretty much what I’ve got but in a nicer box. I perhaps ought to give it another go.
I’ve also had the offer of a free ‘scope from a kind member here, once it is legal and practicable to pick it up.
U
If you've got a source for cheap (but not crap!) 100:1 probes let me know. I've only seen them around £50 and up.
I am looking again at this, having saved up some money from recent gigs (yay!). I had an online chat with Pico Tech, explaining that I'll be working on valve amps where there could be 600V DC lurking, and they confirmed that the 2204A will only withstand a combined potential of 100V. The cathode in a cathode follower typical sits at a higher DC potential than this, and I wouldn't want to blow up either the Pico device or my computer by connecting a probe to it! Do 10:1 and 100:1 probes act as potential dividers, so that the 'scope only 'sees' 1/10 or 1/100 of the actual voltage? And can you get DC-blocking probes with built-in capacitors rated at, say, 1kV?
@urban_winter have you used yours (guessing its the 2204A) in anger yet, and if so how did you get on?
...but...
Googling for circuit diagrams of probes seems to show that they are a voltage divider - which means it should be OK. You could check by putting a multi-meter in place of the oscilloscope input and seeing what voltage you get before you risk plugging it into the 'scope.
I would guess that a DC-blocking capacitor would render the probe unusable for observing waveforms.
U.
I have a couple 1/100 probes, for when I was doing some experimenting with VFDs, 3 phase, and sine wave filters, and they showed a nice 5.4V sine wave.