Activity for 2kind
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Comment | Post #281634 |
Thank you, Andy! Why would I care about ESR(dielectric+true resistance) losses at all and ignore the ESL when looking at AC? Impedance is something I should be caring about. The heck with ESR if ESL will kick into play(and it will at frequencies that are below and higher than the resonance one - plus... (more) |
— | almost 3 years ago |
| Edit | Post #281628 |
Post edited: |
— | almost 3 years ago |
| Edit | Post #281628 | Initial revision | — | almost 3 years ago |
| Question | — |
Capacitor ESR vs. Impedance One of the ceramic capacitors that I've found(link to the capacitor) specifies the following characteristics at 10 kHz: Impedance and ESR graph The difference in value is quite significant, almost 100 fold. Which graph on the picture above better represents real-world use-case? What is the... (more) |
— | almost 3 years ago |
| Comment | Post #281492 |
What might be the reason behind people recommending low-ESR caps put every 1m at the DC link cables for most of the RC stuff? I assumed it was because of the parasitic inductance with the input cables. Your analysis assumed pure ohmic cable characteristics. (more) |
— | about 3 years ago |
| Edit | Post #281478 |
Post edited: Changed the title |
— | about 3 years ago |
| Comment | Post #281478 |
"BLDC inverter" or BLDC motor controller. The unit takes DC input and converts it to a 3 phase voltage/current signal to control the torque or rpm of a motor. How to size the input capacitance of a BLDC motor controller taking input power cable length into consideration - mine calculation above doesn... (more) |
— | about 3 years ago |
| Edit | Post #281478 | Initial revision | — | about 3 years ago |
| Question | — |
Estimating the input capacitance of an BLDC motor controller Problem Description I am trying to design a BLDC inverter and I am in doubt of what would be the right approach for estimating the input capacitor size/type. Doing it empirically or throwing everything in SPICE is one approach, but I would like to understand what is going under the hood and at lea... (more) |
— | about 3 years ago |
| Comment | Post #281295 |
Thanks Olin! Is it usual to refer to "mechanical Hz" or "electrical Hz" when talking about V/Hz ratios? (more) |
— | about 3 years ago |
| Comment | Post #281294 |
How did you get 60? (more) |
— | about 3 years ago |
| Edit | Post #281291 | Initial revision | — | about 3 years ago |
| Question | — |
Max V/Hz value for motor I want to run a specific motor in the open loop. How to calculate the maximum ratio of V/f to run it? Am I looking at Ld or Lq value for this? Let's say these are the characteristics - haven't chosen it yet, but this one should serve the purpose because all important parameters are specified. ... (more) |
— | about 3 years ago |
| Comment | Post #280927 |
Thank you Olin! By putting Q1 in common collector configuration, the role of D2 would not be needed because you could rely on opto’s diode reverse voltage. But I see why you have chosen common emitter. (more) |
— | about 3 years ago |
| Comment | Post #280893 |
It was a typo. Although I intended to have an opto on when input left floating because of no particular reason (more) |
— | about 3 years ago |
| Comment | Post #280900 |
Got it - it's a TVS. (more) |
— | about 3 years ago |
| Edit | Post #280893 |
Post edited: |
— | about 3 years ago |
| Comment | Post #280900 |
If 36V is applied on the left terminal, "Vbr=36V" has no impedance to work against. A small resistor between the input and the Zener would do the job to keep it below max. power dissipation. (more) |
— | about 3 years ago |
| Comment | Post #280894 |
I can't see how is the MCU input high here when R1 is floating. (more) |
— | about 3 years ago |
| Edit | Post #280893 |
Post edited: Added further clarification |
— | about 3 years ago |
| Comment | Post #280791 |
Everyone's right in one way. There is no way to close the question other than deleting it so I will leave it here unanswered. (more) |
— | about 3 years ago |
| Edit | Post #280893 |
Post edited: |
— | about 3 years ago |
| Edit | Post #280893 |
Post edited: |
— | about 3 years ago |
| Edit | Post #280893 | Initial revision | — | about 3 years ago |
| Question | — |
Isolated Digital Input - Overvoltage protection I am trying to build an active-low digital isolated switch capable of withstanding 32VDC voltage without creating any damage to the system. This is the snapshot of the circuit not fulfilling the requirement: Circuit "ISOPINPROG1" will be connected to the switch which will tie to the ground and... (more) |
— | about 3 years ago |
| Comment | Post #280791 |
I've been using 72V extensively and found that 60V was more common simply because it's in the "Low Voltage" category. It was battery-powered, though. Still, why 3.3V and not 3V? Most(every?) of the IC's accepting 3.3V could accept 3V so I assumed there is some historic reason behind the 3.3 value. (more) |
— | about 3 years ago |
| Edit | Post #280791 | Initial revision | — | about 3 years ago |
| Question | — |
Why 3.3V instead of 3V? Usual values used in doing electronics/power supplies are almost always round numbers: - 5V - 12V - 28V - 48V - 60V I understand that in some cases ICs are built to accept the voltage directly coming from the lithium-ion cell in order to simplify the power stage, therefore, havin... (more) |
— | about 3 years ago |
| Comment | Post #280609 |
So you start with setting up the stator field to one of the six possible combinations and trust that the stall torque would be lower than the one you are creating with the field? (more) |
— | over 3 years ago |
| Edit | Post #280606 | Initial revision | — | over 3 years ago |
| Question | — |
BLDC motor - initial rotor position Sensorless BLDC motor controller are becoming more and more popular, especially with rising of the drone industry. Being able to detect where the rotor is at 0rpm or no load seems intuitive if we have hall sensors or resolver. However, what I am having difficulties understanding is how do you... (more) |
— | over 3 years ago |
| Edit | Post #279978 | Initial revision | — | over 3 years ago |
| Question | — |
CAN Bus - Internal Oscillator Every time I needed CAN, I had just put external crystal and didn't think about it after that. It worked fine. I am wondering however whether the precisions of MCU internal oscillator is sufficient for up to 1Mbit/s and could I perhaps prove that on paper. Internal Clock Specification Datash... (more) |
— | over 3 years ago |
| Comment | Post #279961 |
If we assume there is a forward based diode followed by a cap to GND on secondary. (more) |
— | over 3 years ago |
| Comment | Post #279961 |
Thanks, Andy! How does this current limit of 700mA RMS apply on a secondary when potential capacitor there acts as a "short" during the first pulse? If we assume pulse not exceeding 11Vus. (more) |
— | over 3 years ago |
| Comment | Post #279900 |
Only you could estimate the risk given the amount od data. Why connecting the opamp to +-15V when the rest of the circuitry could not grasp that? (more) |
— | over 3 years ago |
| Comment | Post #279816 |
@Andy Aka - Not sure I understood what you meant. I intended on using it instead of a relay so there should be no switching. Converting to push-pull and use gate transformer? In that case, I have no way to desaturate the core without using feedback. If I stay with flyback I have a lot of capacitance... (more) |
— | over 3 years ago |
| Edit | Post #279894 |
Post edited: |
— | over 3 years ago |
| Edit | Post #279894 | Initial revision | — | over 3 years ago |
| Question | — |
Transformer - Vsec or Current rating parameter I am looking at the datasheet of the 7508170315(link) transformer and something seems strange to me. Itable from datasheet If I connect this to a 12V supply and expose it to 10us pulse: 12V10us/475uH = 252mA which is apparently less than the 350mAAC - is it actually? What 350mAAC mean in this c... (more) |
— | over 3 years ago |
| Comment | Post #279816 |
@Andy Aka I will ask a new question based on your comment. This goes beyond the scope. (more) |
— | over 3 years ago |
| Comment | Post #279819 |
@Olin Thanks, it’s clearer now what you meant! In the blog post you linked you claim:
“ Switching power supplies controlled by the pulse on demand scheme may have higher ripple compared to other control schemes. But they are simple, inherently stable...”, what is different in your circuits? Schemati... (more) |
— | over 3 years ago |
| Comment | Post #279819 |
Thanks as always! I've edited question with answers (more) |
— | over 3 years ago |
| Edit | Post #279816 |
Post edited: |
— | over 3 years ago |
| Edit | Post #279816 |
Post edited: |
— | over 3 years ago |
| Edit | Post #279816 |
Post edited: Added answers to comment and answer |
— | over 3 years ago |
| Edit | Post #279816 | Initial revision | — | over 3 years ago |
| Question | — |
Flyback Converter - Output Ripple I am eager to create a flyback converter for driving the high side MOSFET. Here is a snapshot of my work so far: Schematic snapshot of the Flyback Converter Circuit 555 timer starts with generating 100kHz 12V signal on Q1. Q2 is monitoring the voltage on C2 and when it reaches around 18.7V forwa... (more) |
— | over 3 years ago |
| Comment | Post #279728 |
"the FET is on" - I see what I wrote now - it should be "the FET is off". I wouldn't call this silly, especially when the load is motor. (more) |
— | over 3 years ago |
| Comment | Post #279733 |
Thanks for the comment @coquelicot. I made the mistake of not asking the question properly and thereby caused confusion. Will try to avoid this in the future as much as possible. Once again, sorry about that.
Now, the point was not how to parallelize the current flow on the MOSFETs but do's and do... (more) |
— | over 3 years ago |
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