## Explain the output of the old TV flyback transformers.

Started by in sci.electronics.design6 months ago 22 replies

I'm backing off of the neon sign transformer 12kV power supply. For the reasons I was told, the low frequency requires big capacitors. Also, I...

I'm backing off of the neon sign transformer 12kV power supply. For the reasons I was told, the low frequency requires big capacitors. Also, I ordered 20kV caps from Amazon and 6 of the 12 failed at under 4kV. I should have read the reviews, it is well shown these fail. So, I want a continuous DC voltage, I can imagine the old tripler design gave a decent continuous DC, but I'm look

## Two Pole, Low Pass Active Filter with Differential Inputs

Started by in sci.electronics.design5 months ago 19 replies

The circuit has to operate in both differential input and single ended input modes. When in single ended input mode, there's no way to ground one...

The circuit has to operate in both differential input and single ended input modes. When in single ended input mode, there's no way to ground one input, so it will float. In this circuit, the two inputs are tied through C9. So I can't see how this circuit would allow single ended operation. If, however, C9 is split in two, as a pair of 1 uF capacitors to ground, that would se

## violation of causality by purely imaginary impedance functions

Started by in sci.electronics.design9 months ago 3 replies

I've read that the exponential behavior predicted in e.g. RC circuits by taking the Laplace-domain impedance of capacitors to be 1/sC leads to a...

I've read that the exponential behavior predicted in e.g. RC circuits by taking the Laplace-domain impedance of capacitors to be 1/sC leads to a causality violation, and that after much testing of many capacitors some guys named Westerlund and Eklam determined that the true behavior is a probably a power law, which I guess means the dv/dt in I = C dv/dt would actually have to be some kin...

## Capacitors on reels--any tendency for values to cluster?

Started by in sci.electronics.design9 months ago 13 replies

Hi, all, We're making some 7-pole active lowpass filter boards, primarily to go into test systems (ours and other people's). It would be...

Hi, all, We're making some 7-pole active lowpass filter boards, primarily to go into test systems (ours and other people's). It would be convenient to be able to use 0.5% resistors and 5% capacitors. There are 2% caps available in most of the range we want, but they're expensive and relatively scarce. If we could get a few reels of 5% caps, we could dork the resistor values to get ...

Started by in sci.electronics.design11 months ago 12 replies

The Spectrum has a recent article/book review: https://spectrum.ieee.org/open-circuits "The Inner Beauty of Electronic Components" The...

The Spectrum has a recent article/book review: https://spectrum.ieee.org/open-circuits "The Inner Beauty of Electronic Components" The article includes statements clearly addressing the electronic clueless. E.g., "Capacitors are fundamental electronic components that store energy in the form of static electricity." So who are the Spectrum's readers? I always thought it was EE's/des...

## Tough TIA

Started by in sci.electronics.design1 year ago 2 replies

Family. Hiking. Cooking. Eating. I need an electronics break. I'm thinking about a product that measures large (as in 60 feet...

Family. Hiking. Cooking. Eating. I need an electronics break. I'm thinking about a product that measures large (as in 60 feet tall) capacitors, and it needs a tough, hard to damage TIA. AC coupling is fine, and the range is basically audio. Something like this: https://www.dropbox.com/s/mrf7kbvtboktstz/Tough_TIA.jpg?raw=1 One could close a fancy bias servo loop on Q1, but it's hardly...

## LTspice tapped inductor

Started by in sci.electronics.design1 year ago 18 replies

I have an inductor wound on some 22mm plastic pipe, so essentially air-cored. It's over 120 turns, 700mm long and uses resistance wire. It's...

I have an inductor wound on some 22mm plastic pipe, so essentially air-cored. It's over 120 turns, 700mm long and uses resistance wire. It's about 12uH. There are 30 capacitors connected evenly along the coil commoned to a copper pipe busbar. It simulates a long, peculiar transmission line. I want to LTspice it. OK, lots of small inductors with some resistance and the capacitors. ...

## Microcontroller decoupling, >1uF rules?

Started by in sci.electronics.design2 years ago 21 replies

Hi Something that I have been coming back to a number of times: When placing capacitors for decoupling of a microcontroller datasheets...

Hi Something that I have been coming back to a number of times: When placing capacitors for decoupling of a microcontroller datasheets often suggest a 1nF/100nF and maybe a number of them But it needs to be aligned to what is actually the load. Say I have a microcontroller running at 100MHz. Assumption (and that could be wrong), is that for the given technology the switching of the...

## digital capacitor

Started by in sci.electronics.design3 years ago 42 replies

A few people make digital caps. This one is...

A few people make digital caps. This one is nice: https://www.mouser.com/ProductDetail/IXYS-Integrated-Circuits/NCD2100TTR?qs=npTsUczJOtNXvd3UFPIV 7g%3D%3D I'm upgrading an oldish product that used a Maxim part that is, of course, discontinued. Maxim won't even acknowledge the old part number. Nobody in the world seems to have any. The Ixys part has three cap groups, coarse/medium/fine,

## Do Electrolytic Capacitors FREEZE?

Started by in sci.electronics.design5 years ago 24 replies

I have never known what the electrolyte is made from, inside of electrolytic capacitors. Is it a water based material, or oil based? If its...

I have never known what the electrolyte is made from, inside of electrolytic capacitors. Is it a water based material, or oil based? If its water based, it will likely freeze if left outdoors in cold weather. For example, your car radio has caps, and if it's parked outdoors in the winter, the caps in it will freeze. Yet, I have never found my car radio working poorly in cold weather. This ma...

## LM317 compensation

Started by in sci.electronics.design6 years ago 107 replies

LM317's like some ESR in their output capacitors. I don't want any electrolytic or tantalum caps in my new thing, just ceramics, and the sim...

LM317's like some ESR in their output capacitors. I don't want any electrolytic or tantalum caps in my new thing, just ceramics, and the sim sure rings: https://www.dropbox.com/s/11b3w42nsvpliki/317_nocomp.jpg?raw=1 But this fixes it: https://www.dropbox.com/s/9q80heyfbwh5frp/317_comp.jpg?raw=1 This ain't rocket science, but I haven't seen it done before. -- John Larkin ...

## Electronic components aging

Started by in sci.electronics.design10 years ago 86 replies

Speaking of high reliability... I think that it is often a somewhat neglected issue, so I start this thread as a mean to collect *practical*...

Speaking of high reliability... I think that it is often a somewhat neglected issue, so I start this thread as a mean to collect *practical* observations for people who care about long MTBF. In other words, "if I had to build a device which should last 50 years, I would... what?" Resistors (if not overloaded): immortal Ceramic capacitors: as above Tantalum/nobium caps: ? Electrolytic...

## another LT Spice question

Started by in sci.electronics.design10 years ago 35 replies

I have this circuit driving a pulsed laser. I want to compute the energy dumped into the laser and the energy stored in the power...

I have this circuit driving a pulsed laser. I want to compute the energy dumped into the laser and the energy stored in the power supply capacitors. The ballpark is 120 amps into a 20 volt laser for a few hundred microseconds. What I did was create a "B" behavioral current source whose equation is I = V(LASER) * I(LASER) which represents power, and dump that into a 1 farad cap. The...

## Capacitance value for PIC crystal

Started by in sci.electronics.design10 years ago 41 replies

For most of my projects I use either a 14.7456 MHz crystal (57600*256) = or=20 20.000 MHz (for USB 96 MHz 24*f/5). The 20 MHz crystal I am using...

For most of my projects I use either a 14.7456 MHz crystal (57600*256) = or=20 20.000 MHz (for USB 96 MHz 24*f/5). The 20 MHz crystal I am using = specifies=20 a 20 pF parallel load, but my boards have 12 pF capacitors. I just = noticed=20 this and I think the value had been selected for a previous brand of=20 crystal, but the oscillator frequencies measure pretty close to the = ideal=20 ...

## Surge Pulse Clamping with Ceramic Capacitors

Started by in sci.electronics.design11 years ago 40 replies

Hi For an application I need to protect the electronics of an RS485 interface from surges (8/20us 1kV pulse) The normal way be to use a...

Hi For an application I need to protect the electronics of an RS485 interface from surges (8/20us 1kV pulse) The normal way be to use a transzorb, in a SMA housing or even a SOT23 device. That is not possible since we have to be able to withstand up to 30V DC on the bus also (that is handled by a special RS485 IC) The problem is that the selected breakdown voltage of the transzorb ...

## Oscillating regulators with ceramic caps

Started by in sci.electronics.design9 years ago 24 replies

I've just built up a batch of PCBs with several LM317 and LM337 regulators on them. As this thing will be in a hot environment, I wanted to...

I've just built up a batch of PCBs with several LM317 and LM337 regulators on them. As this thing will be in a hot environment, I wanted to avoid electrolytics so I used 10uF MLCC ceramic capacitors on the inputs and outputs of the regulators. Now that I have built it, all of the regulators oscillate! I had thought that it was only LDOs (with the drain or collector of the pass device ...

Started by in sci.electronics.design14 years ago 3 replies

Tariel Kapanadze[1], has invented a multi kilowatt free energy generator. Several different implementations are shown[2][3][4] In one such...

Tariel Kapanadze[1], has invented a multi kilowatt free energy generator. Several different implementations are shown[2][3][4] In one such contraption the components include a radiator buried in the ground, a wire to a water pipe, a Tesla coil/joule thief, a spark gap, transformer, capacitors, 5 ferrite cores from old TV HV transformers, and some other unidentified components.[4] On July...

## X-capacitor failure modes?

Started by in sci.electronics.design10 years ago 49 replies

Folks, This afternoon I took the old HP-4191A apart. Yesterday in the middle of some measurements it went pop-pop-pop, loud, like...

Folks, This afternoon I took the old HP-4191A apart. Yesterday in the middle of some measurements it went pop-pop-pop, loud, like firecrackers. I ran over and turned it off, upon which the popping stopped. An immense amount of light-gray smoke wafted out and it had an odd stench to it. The stench lingered for hours. I can't find any source and upon powering it up the analyzer worked fin...

## Somebody had an idea for a lossless flyback snubber

Started by in sci.electronics.design8 years ago 25 replies

Hey Been trying to find the post with the lossless snubber, with AFAIR a capacitor from the drain node to a regenerative point. I am working...

Hey Been trying to find the post with the lossless snubber, with AFAIR a capacitor from the drain node to a regenerative point. I am working on a 2 switch flyback and some other schemes, but would like to try that novel idea out.... Anyone knows a pointer to the thread? Regards Klaus

## Colpitts crystal oscillator in LTSPICE

Started by in sci.electronics.design8 years ago 59 replies

I'm trying to simulate a low frequency Colpitts oscillator in LTSpice using an NPN darlington and a crystal, and I'm having a lot of trouble...

I'm trying to simulate a low frequency Colpitts oscillator in LTSpice using an NPN darlington and a crystal, and I'm having a lot of trouble getting it to start up. Does anyone have a working one of these? I'm just using a capacitor to simulate the crystal, the parameters I am working with are something like: motional capacitance: 5.3ff ESR = 11k ESI ~ 4500 henries EPR = 100 meg E...