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| DIY DC Current Probe? |
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| capt bullshot:
For a switchmode regulator, this looks pretty good now. The larger ripple in the previous pictures was from the regulators burst mode, this ripple most often is way much larger than the actual switching ripple. Regarding the spikes, double check that these aren't "fake" due to probing technique. Even with good probing technique I see these repeatedly on switchmode regulator outputs. Try probing GND to see the truth. If the spikes are still there, they aren't real on the power rails. Check the real output of the circuit of there's feedthrough and don't be too concerned about what you see here. Otherwise, minimal filtering with a lossy LC or RC often helps you out of there. |
| Jeroen3:
The spikes might indeed be an effect of probing near the inductors. I probe on the special made holes, those connected with the arc and line. Most of the spike disappears when probing on the output capacitors. I did some initial testing at work quickly. And it looks is spot-on. It's within 5mA based on the the Fluke 187 for current and 287 for voltage. If anyone knows how to solder these things (attachment), I would like to know. My 80 Watt iron can't seem get the solder to flow inside the hole... |
| capt bullshot:
Soldering these connectors usually is a matter of a large enough tip for your iron. 80W should be enough, otherwise if you have a second iron at hand, just use both together at one pin. Or pre-heat the connector with a heat gun. |
| Floyo:
Hi Jeroen, looks like an interesting project, I wouldn't mind owning a few of these sensors. I especially like the 2Mhz bandwidth of these sensors and a decent accuracy is a nice plus too. If you'd like I could verify them for high frequency response, I own a Tek current probe that has ample bandwidth to do so. The output looks quite good, probing can be annoying but straight across the output caps with very short leads is usually best. As for the soldering, a big tip together with any sort of preheating helps a lot. I thought a 3mm tip was plenty, that is until I got a 5.5mm tip (on a 80w metcal), it instantly solders almost anything together on a ground plane. |
| Jeroen3:
I can send you one when iteration 2 of the boards are here :-+. I'm not sure if santa will be able to bring it, I don't have any elves. Currently running a heat test, see how if that poses any trouble. Since the sensor does get quite warm. Running 5Amps gives me ~500mV of drop, around 2.5 Watts according to my DP832. Including banana leads. I'll assemble another proto with the 15Amp sensor to see if the board can at least handle those currents. I might need to order a more oz board. Aside from the awful BNC hole (didn't have right drill size) it's looking quite nice. Doesn't topple over either! |
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