OK this one is right from the cover of the last Electronics Design magazine. No one needs stinking ground reference when doing differential "A-B" on a conventional scope.
I've spent way more time on this than I should have but I just don't see the issue here. I've held 2 probes on a board before. Please fill me in so I can sleep tonight.
Here's one from the digikey "catalogue":
https://www.digikey.com/product-detail/en/panasonic-electronic-components/ECW-U1102JX5/PCF1348CT-ND/353833
Look closely at the picture of the capacitor.
OK this one is right from the cover of the last Electronics Design magazine. No one needs stinking ground reference when doing differential "A-B" on a conventional scope.
OK this one is right from the cover of the last Electronics Design magazine. No one needs stinking ground reference when doing differential "A-B" on a conventional scope.
I've spent way more time on this than I should have but I just don't see the issue here. I've held 2 probes on a board before. Please fill me in so I can sleep tonight.
Did you also just connect the probe tips without any connection to ground?
McBryce.
OK this one is right from the cover of the last Electronics Design magazine. No one needs stinking ground reference when doing differential "A-B" on a conventional scope.
I've spent way more time on this than I should have but I just don't see the issue here. I've held 2 probes on a board before. Please fill me in so I can sleep tonight.
Did you also just connect the probe tips without any connection to ground?
McBryce.
Guys, there are situations which you don't need a ground connection. There are certain machines out there that have a true ground rail connected to the plug ground. In that case, the scope is already commoned to the circuit through the ground in the plugs.
OK this one is right from the cover of the last Electronics Design magazine. No one needs stinking ground reference when doing differential "A-B" on a conventional scope.
I've spent way more time on this than I should have but I just don't see the issue here. I've held 2 probes on a board before. Please fill me in so I can sleep tonight.
Did you also just connect the probe tips without any connection to ground?
McBryce.
Guys, there are situations which you don't need a ground connection. There are certain machines out there that have a true ground rail connected to the plug ground. In that case, the scope is already commoned to the circuit through the ground in the plugs.
And all the noise across 5 or 6 metres of ground cable lying beside AC power lines, connected through oxidated ground pins in the socket and passing through an SMPSU isn't having an effect on the signa you're measuringl?? There's a reason why those ground clips are so short. Or are you measuring very high voltage signals where even that would be irrelevant?
McBryce.
And all the noise across 5 or 6 metres of ground cable lying beside AC power lines, connected through oxidated ground pins in the socket and passing through an SMPSU isn't having an effect on the signa you're measuringl?? There's a reason why those ground clips are so short. Or are you measuring very high voltage signals where even that would be irrelevant?
McBryce.
In my case, I work in a relatively clean electrical environment. The ground lead from the board to the scope is 12 inches. I mostly measure TTL level digital and analog from about 100mV to 5V. Nothing earth shattering. Two probes on a board when I use one for the trigger and the other for what I'm measuring. As I said, I've spent way too much time on this. I'll go back to grabbing my soldering iron like a pencil and probe the light bulb that's in my PC power supply.
You have gone too far if your probes are smoking.
It will "work" in that you'll measure something, but with a long ground it may not resemble the signal that is already there. For signals up to a few kHz without sharp transitions it may be ok and may be suitable for a quick go/no-go but without a properly grounded probe take any measurements with a grain of salt. Up in the tens of MHz even a 6 inch ground lead can cause substantial ringing. Risetimes in the nanoseconds will give you more ringing than signal.
Up in the tens of MHz even a 6 inch ground lead can cause substantial ringing.
As I'm sure you are aware, the fundamental frequency (or baud rate) is irrelevant; only the transition is important.
Rule of thumb: a 6" lead on a 15pF *10 probe resonates at ~100MHz.
As I'm sure you are aware, the fundamental frequency (or baud rate) is irrelevant; only the transition is important.
Rule of thumb: a 6" lead on a 15pF *10 probe resonates at ~100MHz.
Sure, but there is a relation between the frequency and transition rate. Typically low frequency signals are not fussy about the transition rate, and the lower the frequency, the smaller the percentage of each state that consists of ringing.
Yes I understand the theory, but in practice I have not encountered many situations at all where a low frequency signal had a particularly fast rise time or the rise time was all that critical.
I can look at the square wave from my function generator using no probe ground at all, just both instruments sharing the same earth ground and it looks fine at low frequency, maybe a bit of ringing if you zoom in on a transition but the period is long enough that the ringing is nothing more than a little glitch on the edge. Dial it up and it starts to get ugly, at some point there is practically nothing but ringing and the waveform looks nothing like it should.
This is all academic anyway though because there's no sense in not properly grounding the probe.
This came from an advertising link on ZDNet for an investment company.
By 2020 everyone will have oneI'm ahead of the crowd. I have some 8 pin DIP's in my parts bins. I'm sure a few of them have bent pins.