Activity for misk94555
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Edit | Post #295488 | Initial revision | — | 7 months ago |
| Question | — |
There are RCD units for DC exist. How do they sense the small DC current difference? There are GFCI (RCD) units for DC. How do they sense the small DC current difference? I understand how GFCI for AC works. It uses a differential current sensing transformer with two opposing primary windings and a sense winding. The turns ratio would be on the order of 1:1:1000. But a tran... (more) |
— | 7 months ago |
| Edit | Post #291367 |
Post edited: update about a solution |
— | 10 months ago |
| Edit | Post #291367 |
Post edited: update about a solution |
— | 10 months ago |
| Edit | Post #294776 |
Post edited: |
— | 11 months ago |
| Edit | Post #294776 |
Post edited: |
— | 11 months ago |
| Edit | Post #294776 |
Post edited: |
— | 11 months ago |
| Edit | Post #294776 | Initial revision | — | 11 months ago |
| Question | — |
Methods to propagate error codes in C firmware I’d like to discuss how to report errors from C functions up the call chain. Consider firmware which communicates to handful of external peripherals (say over I2C and SPI), then validates the data which it has received. The communication could timeout, and that’s an error. The data may end up ... (more) |
— | 11 months ago |
| Edit | Post #294422 |
Post edited: |
— | about 1 year ago |
| Edit | Post #294422 |
Post edited: |
— | about 1 year ago |
| Comment | Post #294425 |
For a moment I though that the input leakage might be a camouflaged but intentional pull-up. But if it were an intentional pull-up, there would be a spec for the min leakage current, and there isn’t a min spec. (more) |
— | about 1 year ago |
| Comment | Post #294425 |
[Texas Instruments](https://www.ti.com/lit/ds/symlink/pca9554.pdf) and [On Semiconductor](https://www.onsemi.com/download/data-sheet/pdf/pca9554-d.pdf) make PCA9554 too. (Don’t know if it’s license copies or knockoffs.) They have the identical -100uA leakage in the datasheets. They didn’t fix it. (more) |
— | about 1 year ago |
| Edit | Post #294422 | Initial revision | — | about 1 year ago |
| Question | — |
Leakage and input currents from PCA9554 I2C GPIO expander I’ve got a simple circuit board where a PCA9554 is controlling the a switch MIC94090YC6. There’s a 100kΩ pull-down resistor. A GPIO pin on PCA9554 is an input on power-up. The leakage current from the PCA9554 input across the 100kΩ developed 1.6V, and it was more than enough for an uncommanded... (more) |
— | about 1 year ago |
| Comment | Post #281325 |
Breakers (and fuses) aren't intended to protect people from electrocution in the first place. They only protect against fire. GFCI protects people against electrocution. (more) |
— | over 1 year ago |
| Comment | Post #293480 |
@#54288 DC servo loop is one way to deal with the DC offset at the in-amp output. The thinking behind the [DC servo loop is explained in this question](https://electrical.codidact.com/posts/288092). It should help increase the usable output range of the in-amp. (more) |
— | over 1 year ago |
| Comment | Post #293398 |
The Elliot (ESP) site is worth checking out for audio projects: https://sound-au.com/site-map.htm (more) |
— | over 1 year ago |
| Comment | Post #293082 |
I also wonder how TIA current nodes can be shielded, when shielding is needed. In general. (more) |
— | over 1 year ago |
| Comment | Post #293082 |
I’ve read that stray capacitance on the op-amp inputs can lead to instability. My summing nodes are going to be 10 meters long, and they are going to run through 10 meters worth of PCBs. That could result in 1200 pF of stray capacitance (3 pF/inch). I guess I should remove the ground plane fro... (more) |
— | over 1 year ago |
| Comment | Post #293310 |
Analog Devices had this app note [AN-1214: High CMRR circuit for converting wideband complementary DAC output to single-ended without precision resistors](https://www.analog.com/media/en/technical-documentation/app-notes/an-1214.pdf). But there are two 49.9Ω resistors to ground, which I’d imagin... (more) |
— | over 1 year ago |
| Comment | Post #293310 |
[matter of general curiosity] The differential current output DACs have two separate current sources. They may be well matched, because they are on the same die. I tried to figure out how well matched they are and how stiff they are, but I haven’t spotted that in the datasheets (Texas Instrume... (more) |
— | over 1 year ago |
| Comment | Post #293310 |
Hi Olin, thanks for the single resistor idea. I’m concerned about imbalance of current between the positive and negative lines. Each line is fed from a separate source, rather than a single current source in a loop. But in my case a single resistor could work, because my contributing currents ... (more) |
— | over 1 year ago |
| Edit | Post #293298 |
Post edited: |
— | over 1 year ago |
| Edit | Post #293298 | Initial revision | — | over 1 year ago |
| Question | — |
Differential current signal to single-ended voltage conversion I’m looking for circuits which convert differential current signal into single ended voltage. If found two topologies in application notes, and though of one more [obvious] topology myself. How do they compare? The app notes where I found these circuits are about converting a differential cu... (more) |
— | over 1 year ago |
| Comment | Post #293274 |
There’s a post somewhere in the bowels of EE.SE where you suggest to not use barium titanate ceramic capacitors because they have microphonic effect. Class II ceramic capacitors (X7R, etc) use barium titanate ceramic. Class I ceramic capacitors (C0G, etc) have low volumetric capacitance. One u... (more) |
— | over 1 year ago |
| Comment | Post #293274 |
I wanted to make sure that the AC-coupling capacitor C28 has a positive DC bias across it, and it isn’t reverse-biased. That was my rationale for V_OFFSET below ½ of the power supply. Similar thoughts about C32 capacitor at the op-amp output. The downstream stage [not shown in my schematic] w... (more) |
— | over 1 year ago |
| Comment | Post #293274 |
The value for the microphone bias resistor R37 will be closer to 1 kΩ than to 100 kΩ. That’s what I had in mind all along. 100 kΩ That was an attention slip on my part. (more) |
— | over 1 year ago |
| Comment | Post #293274 |
Thank you for explaining how you think about this circuit, Olin!
The microphone will be an electret. (I thought that electret mic and condenser mic are different names for same thing.) Did a quick search on DigiKey (although I haven’t settled on the exact model for the mic yet). Something l... (more) |
— | over 1 year ago |
| Edit | Post #293272 |
Post edited: additional information |
— | over 1 year ago |
| Edit | Post #293272 |
Post edited: added another reference link |
— | over 1 year ago |
| Edit | Post #293272 |
Post edited: |
— | over 1 year ago |
| Edit | Post #293272 | Initial revision | — | over 1 year ago |
| Question | — |
Single-supply non-inverting op-amp with an output offset. How to create the output offset? I was looking for electret condenser microphone preamp topologies. I’d like the preamp to run on a single supply, so I’ll have to introduce an output offset. Saw two topologies for introducing the output offset. How do they compare in practice? The 1st topology adds the bias to the input si... (more) |
— | over 1 year ago |
| Edit | Post #291367 |
Post edited: |
— | almost 2 years ago |
| Comment | Post #293082 |
I'm concerned about external noise pickup too. 10m of cable will pick up main AC noise in the bench environment, at the very least. That’s within the band of my sought signal. In principle, I could create a “difference of sums [for lack of a better term]” op-amp. I could make each individual ... (more) |
— | almost 2 years ago |
| Edit | Post #293080 | Initial revision | — | almost 2 years ago |
| Question | — |
Summing op-amp 10 meters long I’ve a linear sensor array (broadside). The array is 10m long and it contains 20 sensors. There’s a limit on the number of wires. I can have a handful of wires running the length of the array, but can’t have an individual wire going to each sensor. I need to sum the signals form the sensors... (more) |
— | almost 2 years ago |
| Edit | Post #292872 | Initial revision | — | almost 2 years ago |
| Question | — |
How does JFET biasing work in a 2-terminal electret condenser microphone? I’m trying to understand the biasing of a 2-terminal electret condenser microphone. The inner workings of a 2-terminal electret microphone are always drawn without a resistor at the JFET source. Is it supposed to be biased like a JFET in a self-bias configuration? If so, how would that work wi... (more) |
— | almost 2 years ago |
| Edit | Post #291367 |
Post edited: |
— | over 2 years ago |
| Edit | Post #291367 | Initial revision | — | over 2 years ago |
| Question | — |
What happens when a microSD card is hot-unplugged? Consider a device with a microSD card. The microcontroller writes to the SD card periodically. The operators have an ability to remove the microSD card at any time (they will be removing it every few weeks). Nothing prevents the operators from hot-yanking the microSD card while it’s being writ... (more) |
— | over 2 years ago |
| Edit | Post #291083 |
Post edited: |
— | over 2 years ago |
| Edit | Post #291083 | Initial revision | — | over 2 years ago |
| Question | — |
LED driver with feedback through light. Which feedback topology is better? I’d like to create a stable IR LED light source. I’ve read that LED efficiency changes with temperature. I’ve seen two designs which used feedback through light to correct the LED temperature drift and aging. They used slightly different topologies. The first topology has one feedback loop ... (more) |
— | over 2 years ago |
| Comment | Post #290874 |
@#36396 I like the idea of an accelerated lifetime test. If I sous vide the sensor in seawater for 2 months at 70°C, that should be equivalent to a year in the field. (Assuming the common rule of thumb that every 10°C accelerates damages by a factor of 2x). I could freeze it a few times along... (more) |
— | over 2 years ago |
| Comment | Post #290874 |
@#8176 **Corrosion.** That’s an interesting question. The electrodes will be ENIG plated. If ENIG isn’t enough, I could do hard gold plating (like PCIe board edge connectors). The metals involved (from top to bottom) are gold, nickel, copper. Gold is a noble metal, so it shouldn’t react wit... (more) |
— | over 2 years ago |
| Comment | Post #290874 |
Olin mentioned at the end of his answer that he’s doing an immersed capacitive level sensor, and it works. I bet there are vias, and they aren’t causing too many issues. (At the same time Olin’s situation is different, because he’s not trying to hold water with a PCB.) (more) |
— | over 2 years ago |