LTSpice: How do make a Schmitt oscillator run?

Started by Joerg in sci.electronics.design12 years ago 8 replies

Ok, simple circuit: Schmitt inverter, 10K resistor from output to input, 1000pF capacitor from input to ground. Vh set to about 20% of Vhigh....

Ok, simple circuit: Schmitt inverter, 10K resistor from output to input, 1000pF capacitor from input to ground. Vh set to about 20% of Vhigh. Should happily oscillate but I get the error message "Time step too small". Also there is a noted dip in voltage down to about 80%, something which should even be possible with a digital behavioral device. What gives? How can I fix that and make i...


How to select shunt capacitor for class E amplifier

Started by amal banerjee in sci.electronics.design2 months ago

Could some electronics guru please help ? I am trying to do some SPICE simulations for class E amplifiers. How is the shunt capacitor value...

Could some electronics guru please help ? I am trying to do some SPICE simulations for class E amplifiers. How is the shunt capacitor value calculated ? Any hints, suggestions would be helpful. Thanks in advance.


Breakdown voltage of PETG in Homemade Capacitor

Started by ngdbud in sci.electronics.design11 years ago 3 replies

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...


OT: Smartphone always charging destroyed battery?

Started by John Doe in sci.electronics.design4 months ago 54 replies

https://www.flickr.com/photos/27532210@N04/ Another Chinese battery bit the dust here. Noticed my smartphone was bulging, the screen was...

https://www.flickr.com/photos/27532210@N04/ Another Chinese battery bit the dust here. Noticed my smartphone was bulging, the screen was warping. The cause was obvious so, not having a torx t1 screwdriver, I ripped it apart. Tried using a capacitor in place of the stock battery but that didn't work. An 18650 works, but it's charged to 4.36 V. The smartphone is used for Wi-Fi security...


BA5406 schematic typo?

Started by Bitrex in sci.electronics.design6 years ago 6 replies

I'm looking at the equivalent schematic for the BA5406 IC power amp here on page 2: http://www.kitsrus.com/projects/ba5406.pdf Pin 3 is a...

I'm looking at the equivalent schematic for the BA5406 IC power amp here on page 2: http://www.kitsrus.com/projects/ba5406.pdf Pin 3 is a boostrap input, I believe to increase the compliance of the current mirror loads and therefore the positive going saturation voltage of the upper Darlington pair, by connecting it via a capacitor to the output. But I don't think it's really intern...


New Switching Converter Topology?

Started by Tim Williams in sci.electronics.design3 years ago 32 replies

Does this... exist? I mean, has it been named, or enumerated...

Does this... exist? I mean, has it been named, or enumerated anywhere? https://www.seventransistorlabs.com/Images/Bidirectional_Buck.png Sort of like a Cuk, but swapping the capacitor and switch. Could be used for low ripple buck (drop D1 and Q2), a kind of extended-winding boost (change D1 to transistor, Q2 to diode, drop Q1 and D2), equalizing source/load (note that switching Q1+Q2...


Question about DC- DC boost converter

Started by Daku in sci.electronics.design9 years ago 13 replies

Could some electronics guru please clarify the following ? The following is the basic structure of a boost converter: DC_in -> inductor --> ...

Could some electronics guru please clarify the following ? The following is the basic structure of a boost converter: DC_in -> inductor --> diode --> capacitor --> output | | | | switch | |


MLCC soldering and dielectric cracking damage

Started by Mr.CRC in sci.electronics.design9 years ago 88 replies

Hi: I frequently assemble PCBs by hand soldering MLCCs of the 0603, 0805, 1206, and a few larger ones (and other parts too--as...

Hi: I frequently assemble PCBs by hand soldering MLCCs of the 0603, 0805, 1206, and a few larger ones (and other parts too--as those capacitor-only circuits aren't much fun!). My hand soldering technique is to use 0.015" wire solder, 1. first adding a tiny bit of solder to one pad. 2. Then I flux both pads, and tack the part to the pad with the added solder. 3. Sometimes at this point,...


Can anyone identify a Klixon TA-22 motor protector

Started by Anonymous in sci.electronics.design9 years ago 9 replies

My well pump keeps cutting out. The capacitor tests ok and the relay contacts appear to be acceptable. There is this Klixon device...

My well pump keeps cutting out. The capacitor tests ok and the relay contacts appear to be acceptable. There is this Klixon device (oddly enough placed inside the case of the capacitor). I'm trying to make up a schematic while diagnosing this whole setup, and dont have water in the meantime. Of course it's the weekend when I can get any local help. What was happening is that the relay ...


Cap leakage

Started by Jamie in sci.electronics.design9 years ago 7 replies

I had to buy some BP/NP caps today "16V 470Uf" and the pickings were slim. In fact, I was looking for a Axial package of that value and could...

I had to buy some BP/NP caps today "16V 470Uf" and the pickings were slim. In fact, I was looking for a Axial package of that value and could not find any one that had stock of that type or even list it. So I ended up getting some Radial types from "NICHICON". "CHicago Capacitor" wanted a min or of 3k pieces at .98 etc, we only need 150 but at least they were willing to make them. But b...


Input impedance of a HPF

Started by Nemo in sci.electronics.design9 years ago 7 replies

I sketched out a VCVS high pass filter with a cutoff of a few hertz, and noticed that the input capacitor is 100nF. Will this cause problems...

I sketched out a VCVS high pass filter with a cutoff of a few hertz, and noticed that the input capacitor is 100nF. Will this cause problems for the circuit driving it, or does the feedback in a VCVS "hide" the capacitance and make the input impedance appear much stiffer? I will be offline for a few days so I won't be able to answer questions. Basically, I was thinking of driving it from an...


Microchip ref design

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

Was looking at one of Microchip's reference designs for a Wheatstone bridge...

Was looking at one of Microchip's reference designs for a Wheatstone bridge sensor. http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en556317 Was curious about how they justify using 20K resistors feeding the ADC input that calls for a 2.5K maximum source impedance. Granted that the ADC input hold capacitor is 25pF and the output of the instrumentatio...


Revisit amps input impedance

Started by amdx in sci.electronics.design8 years ago 39 replies

I got this high input impedance amp out again and redid my input capacitor. I have it at about...

I got this high input impedance amp out again and redid my input capacitor. I have it at about 0.3pf. http://www.crystal-radio.eu/enfetamp.htm The writer says the input impedance is near 5 gigaohms but, I put in a 1 Mhz 4Vpp signal and got out a 4Vpp signal. Then I put a ten Meg in series with the input and my output dropped to about 0.5Vpp. That certainly doesn't seem like it is anywh...


Critic My Ltspice Model

Started by amdx in sci.electronics.design8 years ago 8 replies

Sorry if this is a repost, I didn't see my first post. I'm looking for constructive criticism to create a better model and help me with...

Sorry if this is a repost, I didn't see my first post. I'm looking for constructive criticism to create a better model and help me with the concept I present about the stray capacitance. The concept: the stray capacitance doesn't lower the input impedance it just adds to the resonating capacitor, changing the resonant frequency. The 100meg is supposed to isolate the power supply. (n...


looking for generator manual

Started by Oppie in sci.electronics.design8 years ago 1 reply

Need to troubleshoot a broken generator. Powermate Vertex 7500W Model PM0557523.9 Found owner's manual and parts list but no schematic /...

Need to troubleshoot a broken generator. Powermate Vertex 7500W Model PM0557523.9 Found owner's manual and parts list but no schematic / wiring diagram. Anybody have some resources? The usual googling just gave me more of the same. Tried re-exciting the field to no avail. lead had come off of the capacitor and looks to have been sparking against something. Trying to make sense of wha...


120v LED bulbs -- innards

Started by mkr5000 in sci.electronics.design8 years ago 122 replies

I've actually googled the heck out of this several times but can't seem to get a definitive answer on what is REALLY going on inside a typical...

I've actually googled the heck out of this several times but can't seem to get a definitive answer on what is REALLY going on inside a typical 120v LED bulb. Is it -- ** a capacitor to limit current and a power resistor plus a series stack of leds? (and 60hz flicker isn't noticed?) ** a bridge rectifier (couldn't use a half wave could you?), plus the above? ** or just the rectifier an...


Decapitator For Hire

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

Are you wanting to perform a decapitation? Well, want no more. We can make your dream come true. Low cost decapitation. We'll remove any...

Are you wanting to perform a decapitation? Well, want no more. We can make your dream come true. Low cost decapitation. We'll remove any CAPacitor, from any circuit, regardless of size, shape, or color. Only $19.99 per cap plus shipping, handling, processing, and replacement components. :) The Decapitators


Li-Ion battery model

Started by Yzordderrex in sci.electronics.design8 years ago 8 replies

Greetings. I am involved with a Lithium Ion Phosphate battery charger design. I am trying to get a handle on the behavior of the battery in...

Greetings. I am involved with a Lithium Ion Phosphate battery charger design. I am trying to get a handle on the behavior of the battery in order to figure out how to get it to play nice with the charger. I think the battery is going to act like a big capacitor. It has a 0.25v drop after about 2 amp*hours, and a internal impedance of


Clock Frequency Synthesis

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

I need to design a sine wave synthesizer for six channels. Each channel must have a different frequency and be an exact multiple of 1Hz....

I need to design a sine wave synthesizer for six channels. Each channel must have a different frequency and be an exact multiple of 1Hz. Frequency ranges are from 100Hz to 1Khz. I will do this by filtering out the harmonics of a square wave with an MAX294 switched capacitor filter: http://datasheets.maxim-ic.com/en/ds/MAX293-MAX297.pdf I will need to clock each of the six filter chips at a...


Where'd they go? (Gold electrolytics)

Started by Tim Wescott in sci.electronics.design8 years ago 9 replies

I realized yesterday that gold electrolytics seem to have disappeared from the market. What do folks use when they need a really low-leakage...

I realized yesterday that gold electrolytics seem to have disappeared from the market. What do folks use when they need a really low-leakage capacitor? -- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wesco...