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...

Gentlemen, Setting up voltage-controlled resistors is easy: R=(V(X)+0.01) or whatever. Works, always did. Doing the same with a capacitor...

Gentlemen, Setting up voltage-controlled resistors is easy: R=(V(X)+0.01) or whatever. Works, always did. Doing the same with a capacitor fails with this error message: Error on line 6 : c1 n002 0 c=(v(x)+0.01) Unable to find definition of model "c" * Unknown parameter "x" WARNING: Less than two connections to node X. This node is used by V4. Fatal Error: Missing capacitance ...

Could some electronics guru please clarify a few subtle questions regarding lumped parameter model of transmission lines ? The simple...

Could some electronics guru please clarify a few subtle questions regarding lumped parameter model of transmission lines ? The simple loss-less lumped parameter model consists of an ideal capacitor-inductor pair per unit length. OTOH, the lossy model includes a series resistance with the ideal inductor and an dielectric conductance in parallel with the ideal capacitor. Simil...

Could some electronics guru please hekp ? Maybe this is a stupid question, but here we go. Simple AC kine based lamp dimmers use a diac...

Could some electronics guru please hekp ? Maybe this is a stupid question, but here we go. Simple AC kine based lamp dimmers use a diac triac pair with a capacitor that gets charged via a resistor chain that includes a potentiometer to control the charging rate. When the capacitor gets charged, it discharges via the diac, and this in turn triggers the triac. So far so good. But t...

Hi I am working on a high power frequency inverter (> 1kW) and have a "funny" looking emission graph The converter is the typical inverter...

Hi I am working on a high power frequency inverter (> 1kW) and have a "funny" looking emission graph The converter is the typical inverter type, EMC filter-> 3 Phase Rectifier-> DC Inductor-> DC Link capacitor-> 6 switch Inverter-> Motor Like this: www.electronicsdesign.dk/tmp/Inverter.jpeg We stripped down the circuits and isolated the noise to the EMC filter and bridge rectifier. T

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...

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...

Let's say you need a > 10 microfarad bipolar cap rated to stand off 10 volts, right away, and and all you have in your junk box is a...

Let's say you need a > 10 microfarad bipolar cap rated to stand off 10 volts, right away, and and all you have in your junk box is a 50 microfarad monopolar aluminum electrolytic rated to stand off 50 volts. If you connect the cap, backwards, to a DC supply and limit the current into the cap to something which won't blow it up, the current into the cap will eventually fall close to zero as

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

4.7uF 6.3V X5R dC = -70% @ 6VDC (!!) http://psearch.murata.com/capacitor/product/GRM188R60J475ME19%23.pdf James

4.7uF 6.3V X5R dC = -70% @ 6VDC (!!) http://psearch.murata.com/capacitor/product/GRM188R60J475ME19%23.pdf James

I read many years ago (National app note from memory) that one should connect the inner layer of an inductor to the switch in a buck regulator...

I read many years ago (National app note from memory) that one should connect the inner layer of an inductor to the switch in a buck regulator and the outer layer to the capacitor as the outer layer will then act as a screen. I don't know if it makes a difference in practice but it's free. With many modern inductors it is impossible to see how they are wound so the only indication of "po...

OK, I need to charge a capacitor with a stable constant current. The desired slope is about a volt per nanosecond. So I did...

OK, I need to charge a capacitor with a stable constant current. The desired slope is about a volt per nanosecond. So I did this: https://dl.dropbox.com/u/53724080/Circuits/Fast_Ramp.JPG Things like this tend to oscillate, so I used a fairly slow, high-beta transistor, BCX71K. The ferrite in the collector is supposed to isolate the ramp cap from the transistor capacitance and make ...

Earlier I asked if any one had some data on a Motorola part "SAC722" and I have not had any response to it, however, I think I now have it...

Earlier I asked if any one had some data on a Motorola part "SAC722" and I have not had any response to it, however, I think I now have it all under the hood. These units appear to be TRIACs, and there are two of them in series, maybe for redundancy? Any way, there is a REED contact envelope in there with a couple of turns on it that monitors an 1/2 HP AC capacitor start motor. ...

I'm simulating on LTSpice, a simple amplifier circuit with a 2.5V offset, but if I don't include a capacitor on my input my output hits the...

I'm simulating on LTSpice, a simple amplifier circuit with a 2.5V offset, but if I don't include a capacitor on my input my output hits the rails... why is this? The link shows what I'm doing in LTSpice thanks http://i555.photobucket.com/albums/jj477/panfilero/Capture-1.jpg

Following up on blocher's sterling work,(*) Many of us use parts off-label, often very successfully. A few examples: SAV-551+ pHEMTs make...

Following up on blocher's sterling work,(*) Many of us use parts off-label, often very successfully. A few examples: SAV-551+ pHEMTs make very good wideband bootstraps. Their f_max is around 12 GHz, but they're amazingly stable. 74HC4352s make good flying-capacitor diff amp front ends. TMUX1511s make very nice analogue lock-ins--their Coff*Ron FOM is almost in a class with relays, but...

I'm working on building a high voltage capacitor. I have heard that PET has a very high voltage breakdown. I came across an excellent source of...

I'm working on building a high voltage capacitor. I have heard that PET has a very high voltage breakdown. I came across an excellent source of PETG (Polyethylene Terphthalate Glycol). How much will this affect the puncture resistance? I did a bench test that went alright for being in open air. I'm confident it will handle the voltage I need, but I'd still like some solid numbers. Couldn't fi...

Could some electronics guru here shed some light on this Could a single stage common collector amplifier exhibit amplitude modulation ? I have...

Could some electronics guru here shed some light on this Could a single stage common collector amplifier exhibit amplitude modulation ? I have the SPICE model of a simple common collector amplifier consisting of two base bias resistors, a collector resistor and an input and a output DC blocking capacitor, as well as a source and a load resistor of 50.0 Ohm. The BJT collector is connected to ...

I have this capacitor in a rectangular package with two rows of three dots: black brown green yellow gold brown The other side reads...

I have this capacitor in a rectangular package with two rows of three dots: black brown green yellow gold brown The other side reads EL-MENCO upside down, so the dots may be upside down. The paint is in a recess, where all but the the first two (black brown) are circular. Those are a circle with a point to the right. How must those color codes been read? It always helps if...

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,

I am experimenting with SPICE microstrip dipole antenna models. The series RLC lumped element model is assumed. For a half-wavelength microstrip...

I am experimenting with SPICE microstrip dipole antenna models. The series RLC lumped element model is assumed. For a half-wavelength microstrip dipole antenna, the inductance value of the two microstrip segments is computed using values for trace width, thickness, substrate thickness and effective dielectric constant. The capacitor value is obtained by using resonant frequency