27-11-2014, 03:24 PM
You're doing well! Only a couple of weeks ago we had one go up in a Tek 2465. And another in a Philips 'scope a few months before. Fortunately, they usually smoke for a quite a while, so plenty of opportunity to notice and kill the power before too much of the black stuff has escaped and coated the insides of everything...
Regarding rectifiers, that's an interesting app-note which I don't think I've seen before. The solution you went for (figure 5) is one that I find very interesting. I have used half that circuit (A2) before, as a way of switching the phase of an audio signal - IIRC I first saw it in The Art of Electronics. But combining it with an active clamp is very neat. And I reckon there will be space to build that on my board without it looking too much like an afterthought (I was thinking about using a daughter-board that sits along the LHS of the op-amp if I ran out of space on the existing board). So, that gives me something to experiment with...
I must admit that I liked the "textbook" rectifier because it's what's used in the BBC designed PPM (peak programme meter). Obviously, low-level linearity is not a big issue here. I was also planning to take a look at a few DMM schematics, as even the very cheap ones tend to be pretty good at low frequencies.
Regarding frequency response, I'm not really sure what to expect, and have no fixed idea about what is reasonable. If I get out to a few kHz I guess I'd be happy (for current - I'm expecting voltage to be a little better, but again, no real feeling for what I'll get yet). When making the current measurements, I was planning to use a 1 Ohm shunt resistor or similar to feed into the 'scope. But I'll definitely bear in mind your loan offer if it looks like I'm reaching the limits of what I can easily do using that method
Thanks for your kind words. I'm afraid that most of the stuff on the website is from the BC (before children) era, so these days I don't really get the chance to work on bigger projects. It's taken nearly 10 years to get a half-decent workshop established in this house! The kids are growing up quickly, and I am starting to get a bit more spare time, but I'm finding it harder than ever to get motivated in the evenings. I don't know if that's because the day job is more demanding (which is definitely is!), or because I'm getting older (I definitely am!), or if broadband is getting in the way (I'm sure it definitely is!).
I'm quite jealous of your laser cutter - sadly we don't have such exciting toys here. The possibilities
Regarding rectifiers, that's an interesting app-note which I don't think I've seen before. The solution you went for (figure 5) is one that I find very interesting. I have used half that circuit (A2) before, as a way of switching the phase of an audio signal - IIRC I first saw it in The Art of Electronics. But combining it with an active clamp is very neat. And I reckon there will be space to build that on my board without it looking too much like an afterthought (I was thinking about using a daughter-board that sits along the LHS of the op-amp if I ran out of space on the existing board). So, that gives me something to experiment with...
I must admit that I liked the "textbook" rectifier because it's what's used in the BBC designed PPM (peak programme meter). Obviously, low-level linearity is not a big issue here. I was also planning to take a look at a few DMM schematics, as even the very cheap ones tend to be pretty good at low frequencies.
Regarding frequency response, I'm not really sure what to expect, and have no fixed idea about what is reasonable. If I get out to a few kHz I guess I'd be happy (for current - I'm expecting voltage to be a little better, but again, no real feeling for what I'll get yet). When making the current measurements, I was planning to use a 1 Ohm shunt resistor or similar to feed into the 'scope. But I'll definitely bear in mind your loan offer if it looks like I'm reaching the limits of what I can easily do using that method
Thanks for your kind words. I'm afraid that most of the stuff on the website is from the BC (before children) era, so these days I don't really get the chance to work on bigger projects. It's taken nearly 10 years to get a half-decent workshop established in this house! The kids are growing up quickly, and I am starting to get a bit more spare time, but I'm finding it harder than ever to get motivated in the evenings. I don't know if that's because the day job is more demanding (which is definitely is!), or because I'm getting older (I definitely am!), or if broadband is getting in the way (I'm sure it definitely is!).
I'm quite jealous of your laser cutter - sadly we don't have such exciting toys here. The possibilities
