## capacitor nonlinearity again

Started by in sci.electronics.design9 years ago 31 replies

Does anybody have an LT Spice example that models the C-V dependence of a ceramic cap? I was thinking about the parametric frequency divider...

Does anybody have an LT Spice example that models the C-V dependence of a ceramic cap? I was thinking about the parametric frequency divider that I did with a diode, and it occurs to me that a capacitor's c (probably) falls off symmetrically with +- voltage, but a diode is asymmetric. So the capacitor based parametric divider is different. It might be fun to play with that. -- Jo...

## DCDC buck converter output capacitor placement

Started by in sci.electronics.design8 years ago 5 replies

I have a microprocessor with built in DCDC converter. We need to provide in= ductor and output capacitors externally at the respective pins of...

I have a microprocessor with built in DCDC converter. We need to provide in= ductor and output capacitors externally at the respective pins of the proce= ssor. The regulated o/p from the internal DCDC converter is for internal co= re and IO as well as for external peripherals. The manufacturer recommends = using 0.01uf, 0.1uf, 1uf and 33uf at the DCDC output pin. What should be th= e order of...

## Looking for low-frequency PIN diode

Started by in sci.electronics.design8 years ago 19 replies

I=92m developing a simple, five-frequency superhetrodyne receiver to operat= e between 2.5 MHz to 20 MHz in which the local oscillator crystals...

I=92m developing a simple, five-frequency superhetrodyne receiver to operat= e between 2.5 MHz to 20 MHz in which the local oscillator crystals and whip= antenna tuning circuits are selected (switched) using diodes. Here=92s the= problem:=20 The whip tuning circuit is comprised of a single variable capacitor with fi= ve fixed-value inductors, each in series with a BA277 "bandswtiching" di...

## Sharing idea, eliminating IO leakage currents

Started by in sci.electronics.design2 years ago 6 replies

Hi This may have been done before, but for me it was a solution to a week long problem with a circuit Say you have a voltage you need to...

Hi This may have been done before, but for me it was a solution to a week long problem with a circuit Say you have a voltage you need to measure with an ADC, let say 10V We need a voltage divider to bring it down to ADC range. That divider is normally of high resistance to not load the signal to much The problem is the leakage current of the ADC and the sample/hold capacitor of the ADC...

## Building an LED microflash

Started by in sci.electronics.design8 years ago 15 replies

I am having a little fun thinking around corners. I have a huge array of LEDs and I want to pulse them on and off quickly (on= ce). A trip...

I am having a little fun thinking around corners. I have a huge array of LEDs and I want to pulse them on and off quickly (on= ce). A trip switch will trigger the LED flash briefly.=20 I need help with the circuit design. I'll try to show what I need done... The LEDs are all in parallel and are 3v. The input voltage will be from a 3= v DC supply (a coin cell). A capacitor will c...

## capacitor heatsinks

Started by in sci.electronics.design8 years ago 75 replies

Interesting: http://www.aavid.com/product-group/capacitors -- John Larkin Highland Technology...

Interesting: http://www.aavid.com/product-group/capacitors -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermoco...

## Backfed MOSFET current limit

Started by in sci.electronics.design8 years ago 26 replies

Got a circuit. I'm using a high-side P-channel MOSFET to prevent damage when the battery is put in backwards. The FET is put in "backwards"...

Got a circuit. I'm using a high-side P-channel MOSFET to prevent damage when the battery is put in backwards. The FET is put in "backwards" (battery to drain, circuit to source) to point the body diode in the correct direction. When the battery is inserted, a capacitor on the circuit side of the FET charges up, sucking a considerable amount of current very briefly. The current is b...

## PFC circuit at end of a long resistive line

Started by in sci.electronics.design8 years ago 13 replies

Gents, Have any of you run a PFC boost circuit from a 50 or 60Hz AC line with a loop resistance on the order of 100 ohms? We are currently...

Gents, Have any of you run a PFC boost circuit from a 50 or 60Hz AC line with a loop resistance on the order of 100 ohms? We are currently looking for the most efficient method of delivering 1Kwatt through a lossy cable. Method one is the simple step down transformer followed by a rectifier bridge. The concern here is the poor PF of the rectifier bridge had large capacitor bank. ...

## vehicle battery supercapacitor kit ideas

Started by in sci.electronics.design2 years ago 15 replies

Hi, I have installed and tested a supercap on a V8 engine as an experiment to avoid buying a new lead acid battery: Here is the supercap I...

Hi, I have installed and tested a supercap on a V8 engine as an experiment to avoid buying a new lead acid battery: Here is the supercap I used: https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board -Module/223685920878 (16V-83F) I soldered ring terminals to it and bolted it directly to the 12V battery (in parallel with the battery). Be

## One Pulse High Voltage Switch

Started by in sci.electronics.design8 years ago 21 replies

Hi all, i need a switch that can handle one pulse of 4Kv for discarge a 0.1 uF 4Kv capacitor. How can i do this? IGBT Array? Can someone help...

Hi all, i need a switch that can handle one pulse of 4Kv for discarge a 0.1 uF 4Kv capacitor. How can i do this? IGBT Array? Can someone help me without using BIG SCR? Thanks a lot!

## Cap Multiplier, NOT a "gimmick"

Started by in sci.electronics.design8 years ago 13 replies

Here's a way to do capacitor multiplication... limited only by OpAmp GBW product, and no resistive components until the OpAmps run out...

Here's a way to do capacitor multiplication... limited only by OpAmp GBW product, and no resistive components until the OpAmps run out of steam. Mathematically, this is the same way I did behavioral models for crummy capacitors such as X7R and Y5U, except I had ideal amplifiers, and equations and/or tables to des

## X-capacitor failure modes?

Started by in sci.electronics.design8 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...

## Where to get 'capacitor kit' for Element TV, ELGFT-401 ?

Started by in sci.electronics.design8 years ago 7 replies

tried to post to the sci.electronics.repair group through AIOE and got 441 Banlist error message ?? yet, I can read messages there, coming...

tried to post to the sci.electronics.repair group through AIOE and got 441 Banlist error message ?? yet, I can read messages there, coming through eternal-september, just can't reply, or post evidently. = = = Any ideas where to get a capacitor kit for this TV? Or, a list of problem caps and placement?

## Motor starting switch

Started by in sci.electronics.design8 years ago 18 replies

pain in the tail, my FAIP H150 electric power washer died. The motor starting capacitor went (oozed out the side of plastic shell). Replaced it...

pain in the tail, my FAIP H150 electric power washer died. The motor starting capacitor went (oozed out the side of plastic shell). Replaced it with a similarly rated phenolic case starting cap but noticed it's getting very warm. More than likely the motor centrifugal switch is stuck closed. It is a TEFC motor so getting to the switch is a major pain. Not to mention that I don't see a re...

## single transistor oscillator

Started by in sci.electronics.design8 years ago 11 replies

I tried building a single transistor LED flasher like this...

I tried building a single transistor LED flasher like this : http://cappels.org/dproj/simplest_LED_flasher/Simplest_LED_Flasher_Circuit.html I didn't have the recommended 2n2222 - I tried with a BC548, 2n2369 and 2n3055 - None of them work. I'm using a trimpot set to 2 kiloohms and a 470 microfarad capacitor. Instead of a 100 ohm resistor I put 3 superbright LEDs in series. I get 1.2 v...

## Power supply topology question ...

Started by in sci.electronics.design8 years ago 18 replies

Could some electronics guru please shed some light on the following. The standard topology for a linear regulated power supply is basically...

Could some electronics guru please shed some light on the following. The standard topology for a linear regulated power supply is basically as follows: isolation step-down transformer | v rectifier(bridge or 2 - diode) | v capacitor ripple filter bank | v voltage regulator ...

## How high do tantalum capacitor values go ?

Started by in sci.electronics.design8 years ago 15 replies

This is a general query for all the posters on this forum. In your experience, what is the maximum value tantalum capacitor that you have used....

This is a general query for all the posters on this forum. In your experience, what is the maximum value tantalum capacitor that you have used. I have been told that as tantalum is much more expensive and the processing costs are a lot higher, high value tantalum capacitors(e.g., 1000 uF) do not exist. Is this true ?

## Floating impedance simulator idea

Started by in sci.electronics.design8 years ago 2 replies

Use 4 optoisolated current sources/sinks under microprocessor control, and sense the terminal voltage/current at each of the two ports. Apply...

Use 4 optoisolated current sources/sinks under microprocessor control, and sense the terminal voltage/current at each of the two ports. Apply the appropriate passive device defining equations in software to simulate a floating inductor, capacitor, negative impedance, etc. Something like this maybe: http://i.imgur.com/i8nSruE.png PWM output goes to the NPN current sources, op amps s...

## LPF Chebychev Q re: input/output capacitors

Started by in sci.electronics.design8 years ago 26 replies

I found a 13 element 150 Mhz to 174 Mhz adjustable (pinch/stretch the coils?) filter in my junk box, It has seven capacitors marked as...

I found a 13 element 150 Mhz to 174 Mhz adjustable (pinch/stretch the coils?) filter in my junk box, It has seven capacitors marked as below. 10 E---30pf---36pf---40pf---36pf---30pf---10 E All caps are silver mica, labeled 850 volts. I wonder about the values of the first and last capacitor, also why are the special? I have found a calculator for multi element chebychevs, but can't match...

## Paralleling Three Full Wave Rectifier Bridges

Started by in sci.electronics.design8 years ago 54 replies

Hi everyone, I am trying to build a relatively high voltage-high current DC source. The scheme is simple and uses no regulation (therefore no...

Hi everyone, I am trying to build a relatively high voltage-high current DC source. The scheme is simple and uses no regulation (therefore no feedback control). The scheme is as follows: Utility mains supply => Variac => Three full wave rectifier bridges in parallel => Huge capacitor bank => Load. Variac: something similar to this one: http://orgchem.colorado.edu/Technique/Equipm