Hi,
My first and most recent post here was about a PSU that I'd killed. I'm new to electricity so I tried to check some passives with my meter and couldn't find anything wrong, then set it aside until I learned more. Somehow, I saw Fred Flintstone's DSO for sale at a swap meet; the afternoon was ending and he didn't want to transport the six cubic feet and 65 pounds back to wherever.
For the price, I'm very pleased with its performance and condition, it is usable but not so nice in terms of today's fashion: it has nice analog bandwidth but really slow sampler and kind of weak ADC. At the flea market, there was a generator set up with it, so I started turning it up. It lost the wave somewhere above 600 MHz. That's all I knew about this machine when I paid for it, about half of what it's worth in steel, copper, and gold, and he gave me some probes too.
The probes I got are 10x probes that present a 1 meg ohm resistance to ground on their own, and 0.9 meg ohm series resistance to the input. The matching inputs have 1 meg ohm across the input and ground. I read Wikipedia, put 10 megs in series with the probe and touched it to my 13.8vdc power supply. Setting the probe input to 100x instead of 10x put the trace about where it should be on the scale (ie. on the center with offset showing 13.8 V instead of 1.38 V.) Interesting I was expecting it to be something like 10% off.
Is it really this easy to get a 100x probe? Would 9.1 meg ohm be a more correct choice?
Since these inputs are rated for +/- 2V, maybe a 200x probe would be useful to me and could I accomplish this with 20 meg ohm in series? How much voltage will I even need to handle when probing an SMPS? 600v? 1000v?
So, this scope has all of 7 bits of resolution, I think this is rather limited in terms of dynamic range nowadays. Can I use a capacitor in series to remove DC bias from a wavey signal and center it on 0 volts? I have no idea how waves, impedance, AC, and these related things work yet.
Hmm. My parts place has 100 meg ohm resistors in stock. That would be just super if I could probe at neon sign transformers and CRT anodes!
My first and most recent post here was about a PSU that I'd killed. I'm new to electricity so I tried to check some passives with my meter and couldn't find anything wrong, then set it aside until I learned more. Somehow, I saw Fred Flintstone's DSO for sale at a swap meet; the afternoon was ending and he didn't want to transport the six cubic feet and 65 pounds back to wherever.
For the price, I'm very pleased with its performance and condition, it is usable but not so nice in terms of today's fashion: it has nice analog bandwidth but really slow sampler and kind of weak ADC. At the flea market, there was a generator set up with it, so I started turning it up. It lost the wave somewhere above 600 MHz. That's all I knew about this machine when I paid for it, about half of what it's worth in steel, copper, and gold, and he gave me some probes too.
The probes I got are 10x probes that present a 1 meg ohm resistance to ground on their own, and 0.9 meg ohm series resistance to the input. The matching inputs have 1 meg ohm across the input and ground. I read Wikipedia, put 10 megs in series with the probe and touched it to my 13.8vdc power supply. Setting the probe input to 100x instead of 10x put the trace about where it should be on the scale (ie. on the center with offset showing 13.8 V instead of 1.38 V.) Interesting I was expecting it to be something like 10% off.
Is it really this easy to get a 100x probe? Would 9.1 meg ohm be a more correct choice?
Since these inputs are rated for +/- 2V, maybe a 200x probe would be useful to me and could I accomplish this with 20 meg ohm in series? How much voltage will I even need to handle when probing an SMPS? 600v? 1000v?
So, this scope has all of 7 bits of resolution, I think this is rather limited in terms of dynamic range nowadays. Can I use a capacitor in series to remove DC bias from a wavey signal and center it on 0 volts? I have no idea how waves, impedance, AC, and these related things work yet.
Hmm. My parts place has 100 meg ohm resistors in stock. That would be just super if I could probe at neon sign transformers and CRT anodes!
