Battery management system (BMS) using PMOSFETs and optoMOS for shunt balance

Started by P E Schoen in sci.electronics.design5 years ago

I've made some changes and corrections to my previous design, and it is now ready for prototype PCBs. It uses discrete PMOSFETs to select one of...

I've made some changes and corrections to my previous design, and it is now ready for prototype PCBs. It uses discrete PMOSFETs to select one of four series-connected lithium cells, and transfers charge to a capacitor. Then the MOSFETs are turned off and other MOSFETs apply that charge to the ADC input of a PIC through a voltage divider to measure the voltage of that cell. The top three ...


Buck regulator chips

Started by Phil Hobbs in sci.electronics.design5 years ago 27 replies

Modern buck regulators seem to have way too many features that I can't turn off or customize. The otherwise very nice AOZ1282-1 snookered me...

Modern buck regulators seem to have way too many features that I can't turn off or customize. The otherwise very nice AOZ1282-1 snookered me by having a 600-us fixed short-circuit protection interval--it wouldn't start up into a 220 uF capacitor, even with a very light load. Fortunately, switching to 22 uF fixed it, and I had some with the right footprint. And then many go into stut...


Electrolytic Capacitor as Audio Test Load

Started by Steve Morris in sci.electronics.design5 years ago 17 replies

I was wondering what would happen if I wired the output of a 100W audio amplifier directly across a sizable (4700uF) electrolytic...

I was wondering what would happen if I wired the output of a 100W audio amplifier directly across a sizable (4700uF) electrolytic capacitor. It could be assumed the amp is push-pull and the cap is polarized. How would it react in terms of a test load? Steve Morris


OT: Running a pedestal fan in reverse - failed - a rant of sorts.

Started by Sylvia Else in sci.electronics.design5 years ago 64 replies

For reasons I need not go into, I wanted to make a cheap pedestal fan blow backwards, by putting the fan on backwards, and running the motor...

For reasons I need not go into, I wanted to make a cheap pedestal fan blow backwards, by putting the fan on backwards, and running the motor in reverse. The motor is a typical PSC motor, and reversing it should be just a matter of switching a pair of connections to put the capacitor into the other phase. It took me a while to figure out which two wires to swap, but I'm confident I ...


Still more proof that nobody can get the IC style MOSFET symbol right...

Started by Tim Williams in sci.electronics.design5 years ago 12 replies

http://www.transphormusa.com/document/datasheet-tpd3215m-600v-cascode-gan-module/ The diagram on the cover sheet is already meaningless, but...

http://www.transphormusa.com/document/datasheet-tpd3215m-600v-cascode-gan-module/ The diagram on the cover sheet is already meaningless, but the best part is comparing that to the diagram on page 8. If they stopped trying to be cute and just drew what the thing actually is, there'd be no confusion... Also, they stick a capacitor in there -- as they must -- but don't document it, any...


muRata GC3-series dielectric has capacitance superior to X7R under d.c. bias

Started by Anonymous in sci.electronics.design5 years ago 8 replies

I happened to stumble on this today, qualifying parts... (You'll have to look on page 43 of this monster .PDF to see the performance...

I happened to stumble on this today, qualifying parts... (You'll have to look on page 43 of this monster .PDF to see the performance graph) https://www.murata.com/~/media/webrenewal/support/library/catalog/products/capacitor/mlcc/c03e.a shx This 35V 0603 100nF X7R from Taiyo-Yuden (GMK107B7104KAHT) isn't bad either, only -20% @ 25V, 30% down at 32VDC: http://ds.yuden.co.jp/TYCOMPA


Abusing the LM386

Started by bitrex in sci.electronics.design4 years ago 77 replies

Use two bridged to drive say a little PCB-mount 2k - 8 ohm audio transformer "backwards" to charge a HV capacitor, current feedback from each...

Use two bridged to drive say a little PCB-mount 2k - 8 ohm audio transformer "backwards" to charge a HV capacitor, current feedback from each side of the "primary" inductance keeps the drive current waveform from going all sloppy, cross-coupling the G1 pins boosts each amplifier's "open loop" gain.


In Doubt - Circuit Values

Started by Anonymous in sci.electronics.design4 years ago 20 replies

This is part of a piece of equipment that is to detect a short. The FUT will be a capacitor. It is not the only function of the unit, I am working...

This is part of a piece of equipment that is to detect a short. The FUT will be a capacitor. It is not the only function of the unit, I am working on the rest. This seems so simple but I have doubts for some reason. Since I am learning LTSpice finally. R 5 & 6 set the input at ½ Vcc. R 3 & 4 set the emitter of Q 1 low enough to assure saturation - I think. Seems like it anyway.


Brittle Fracture Ceramic Capacitors

Started by Steve Wilson in sci.electronics.design4 years ago 17 replies

While researching failure modes, I came across a number of articles on brittle fracture of ceramic capacitors that may be of interest to some....

While researching failure modes, I came across a number of articles on brittle fracture of ceramic capacitors that may be of interest to some. Sorry for the wrap. https://www.murata.com/support/faqs/products/capacitor/mlcc/mnt/0007 https://www.johansondielectrics.com/capacitor-cracks-still-with-us-after-all- these-years https://product.tdk.com/info/en/products/capacitor/ceramic/mlcc/...


Component help - what is a V200LA40A

Started by Carl Ijames in sci.electronics.design4 years ago 2 replies

An acquaintance has a automotive machine tool (basically a mill) that died. He said that two fuses were blown and what looks like a disc...

An acquaintance has a automotive machine tool (basically a mill) that died. He said that two fuses were blown and what looks like a disc capacitor was melted on a board that makes dc for a variable speed motor from 115VAC. No visible markings on the component but "V200LA40A" is silk screened under it. Naturally he has no diagrams or parts lists. Google comes up "no results" for that, w...


Hoq to measure capacitor Q from SPICE

Started by Anonymous in sci.electronics.design4 years ago 2 replies

Could some electronics guru here shed some light on this ? How do measure Q for say a capacitor using SPICE simulation ? I know how to measure...

Could some electronics guru here shed some light on this ? How do measure Q for say a capacitor using SPICE simulation ? I know how to measure reflection coefficient, insertion loss and SWR from a SPICE AC analysis. Any hints/pointers in regard to the Q measurement with SPICe simulation will be greatly appreciated. Thanks in advance.


Ceramic capacitor data on the web

Started by Phil Hobbs in sci.electronics.design4 years ago 4 replies

Hi, All, Given all the churn in the parts business at the moment, I've been spending an unconscionable amount of time finding suitable...

Hi, All, Given all the churn in the parts business at the moment, I've been spending an unconscionable amount of time finding suitable replacements for out-of-stock parts. High value ceramic caps are the worst. Most makers have websites where you can look at the C(V) curves: AVX: (This one is super clunky--every time you select something it displays a throb


Zeta flying capacitor

Started by Piotr Wyderski in sci.electronics.design4 years ago 24 replies

I want to add a Pb accumulator charging capability to a power path prioritizer. Since I need to have a high-side N-MOSFET driver anyway, the...

I want to add a Pb accumulator charging capability to a power path prioritizer. Since I need to have a high-side N-MOSFET driver anyway, the Zeta topology pops up rather naturally. The specs are: V_OUT=13.8V/4A, 200kHz, V_IN=9..20V. There will also be a current slope-limiting input choke (to buy some time for the overcurrent fuse to react), which adds a nice side-effect of smoothing the Zeta...


Exceeding ceramic capacitor rated voltage.

Started by Winfield Hill in sci.electronics.design4 years ago 24 replies

What do you think will happen if the data-sheet's rated voltage for a ceramic capacitor is exceeded? E.g., Kemet C0805C105J4RAC, an 0805 X7R...

What do you think will happen if the data-sheet's rated voltage for a ceramic capacitor is exceeded? E.g., Kemet C0805C105J4RAC, an 0805 X7R 1.0uF 16V type; could see 18.6V from a solar-cell panel. -- Thanks, - Win


AC-fed SMPS topologies or the lack thereof

Started by Piotr Wyderski in sci.electronics.design4 years ago 30 replies

Why there seem to be no AC-fed SMPS topologies? Google is surprisingly silent about that. There are some attempts to bulid a bridgeless PFC, but...

Why there seem to be no AC-fed SMPS topologies? Google is surprisingly silent about that. There are some attempts to bulid a bridgeless PFC, but they still have the high-voltage electrolytic capacitor in the middle and in most cases they do not address the inrush current issues at all, as the PFC is a more or less typical buck, i.e. a series connection of L-> D-> C. The lack of this storage c


How to select transistor for oscillator ?

Started by Anonymous in sci.electronics.design4 years ago 45 replies

Could some electronics guru here please help ? What is the best way to select a transistor for an oscillator ? Consider a Colpitts oscillator...

Could some electronics guru here please help ? What is the best way to select a transistor for an oscillator ? Consider a Colpitts oscillator running at 5 MHz. The following are the analysis steps. 1. Select a value for the LC tank capacitor C1 = C2 = C 2. Select a load e.g., R=50 Ohm 3. To start oscillations, gmR > C2/C1. In this case gmR > 1 4. Using the oscillation frequency and


ESR Meter confusion

Started by Anonymous in sci.electronics.design4 years ago 87 replies

One of my digital multimeters has a capacitor test built into it. But I dont believe that tests the ESR. I've recently read many articles...

One of my digital multimeters has a capacitor test built into it. But I dont believe that tests the ESR. I've recently read many articles and watched videos about testing the ESR of caps. I wanted to buy an inexpensive ESR tester and went to ebay. I am just a hobbyist on a low fixed income so I cant pay a lot. Anyhow, that is where I got real confused. Several say ESR, while others are ju...


PCB-design flaw causes capacitor failures...

Started by Winfield Hill in sci.electronics.design4 years ago

EDN story from 2009. Excerpt. https://www.edn.com/electronics-blogs/tales-from-the-cube/4313394/A-bad-capacitor-story-ends-hap pily "The...

EDN story from 2009. Excerpt. https://www.edn.com/electronics-blogs/tales-from-the-cube/4313394/A-bad-capacitor-story-ends-hap pily "The bad capacitor had a via at the positive terminal, but, at the negative end, there was a heavy trace going inside the footprint, beneath the capacitor, and only then outside. ... On the positive terminal, the solder stayed where it was supposed to,


How to stop electrical whining noise?

Started by John Doe in sci.electronics.design4 years ago 40 replies

https://youtu.be/FSwZQtqWyHw Can that whining noise be easily eliminated? I am assuming its origin is easy for some to guess. It uses...

https://youtu.be/FSwZQtqWyHw Can that whining noise be easily eliminated? I am assuming its origin is easy for some to guess. It uses brushless motors controlled by an "electronic speed control" (ESC). There is a large cap across each ESC supply plus and minus. I tried adding a 1000 ?F low ESR capacitor on the battery input but that didn't help. Thanks.


Calculate capacitor replacement value?

Started by Anonymous in sci.electronics.design4 years ago 32 replies

Troubleshooting a ‘Kitchen Timer’ I made some 20 years ago, I found the culprit was the capacitor, nominally 1500uF but now lifeless....

Troubleshooting a ‘Kitchen Timer’ I made some 20 years ago, I found the culprit was the capacitor, nominally 1500uF but now lifeless. Its actual original value is unknown. There are 8 markings on the knob of the timer’s linear pot (1 to 8 minutes) and 11 on the knob of a 1Px12W rotary switch (from 10 to 150 minutes) . As a first (arguably optimistic) first st