Relaxation oscillators and SPICE

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

I am unable to simulate the followingg PUT-based relaxation oscillator in the most recent LTspice (with BC547B and...

I am unable to simulate the followingg PUT-based relaxation oscillator in the most recent LTspice (with BC547B and BC557B): https://upload.wikimedia.org/wikipedia/commons/9/9f/PUT_LED_blinker.png Nothing wants to oscillate. Looking for a bug I have also tried the simplest possible neon lamp oscillator (with Vstrike=100V, Vhold=50V, R=220k, C=1u), but there are no scillations either: ...


LT Spice plot axis question

Started by John Larkin in sci.electronics.design3 years ago 4 replies

Are there command lines to change the waveform axes? I want to do a frequency sweep with y-axis in volts, in a fixed range. The HELP...

Are there command lines to change the waveform axes? I want to do a frequency sweep with y-axis in volts, in a fixed range. The HELP isn't much help. I can do it manually, every time I do a run, but that gets tiresome. Basically, I built a sort of VNA to analyze a control system. Instead of running a zillion test cases with various loads, I thought that looking at loop Zout would spo...


Uart through an audio transformer

Started by Martin Griffith in sci.electronics.design14 years ago 27 replies

Any rules of thumb about sending a 9600 baud UARTsignal ,from an 8051 through a telecom type V90 audio transformer, (LT spice K L1 L2 1 @ 4mH Rs...

Any rules of thumb about sending a 9600 baud UARTsignal ,from an 8051 through a telecom type V90 audio transformer, (LT spice K L1 L2 1 @ 4mH Rs = 10R) I only need about 8 bytes of data, and LTspice seems to need a square wave for about a millisecond before it settles down. So a long sync word of 010101 etc then a start byte? I'll pad the sig down to 100mV or so martin


Simple circuit to flash an LED from RF

Started by amdx in sci.electronics.design4 months ago 27 replies

I'd like to setup a high Q LC to receive a local Radio station probably charging a cap, when the charge is high enough flash an LED. Maybe set...

I'd like to setup a high Q LC to receive a local Radio station probably charging a cap, when the charge is high enough flash an LED. Maybe set the trigger point of an SCR, or could just a zener do it. I don't have LT spice, so please don't post and answer with that.                                 Thanks, Mikek -- This email has been checked for viruses...


simulating TI switchers

Started by John Larkin in sci.electronics.design1 month ago 10 replies

We are using TPS54302 and TPS562208. I haven't been able to get their Pspice models to work in LT Spice. They throw goofy errors, or run...

We are using TPS54302 and TPS562208. I haven't been able to get their Pspice models to work in LT Spice. They throw goofy errors, or run but at fs speeds and make no useful progress. TI apparently has their own sim, Cadence maybe, that might run these parts. Does anyone know how to do that, run the TI models with the TI software? Or to get the Pspice models to run usefully in LT Spic...


Is This Spice Model Accurate?

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

This model for a PMOSFET shows VTO=1.00. The data sheet shows VGS(th) as -1.0 to -0.45 volts. I'm guess these are two different specs? One...

This model for a PMOSFET shows VTO=1.00. The data sheet shows VGS(th) as -1.0 to -0.45 volts. I'm guess these are two different specs? One is where the current is at a specified level and the other is where the current starts to change from the cut off condition? Here is the model for this part. *SRC=DMP2240UDM;DI_DMP2240UDM;MOSFETs Enh;20.0V 2.00A 0.150ohms Diodes Inc MOSFET .M...


Spice Model for OpAmp Output Stage

Started by Jim Thompson in sci.electronics.design6 years ago 18 replies

...Jim Thompson -- | James E.Thompson | mens | | Analog...

...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Cont


coupled resonators

Started by John Larkin in sci.electronics.design8 years ago 17 replies

Cool visual patterns: https://dl.dropboxusercontent.com/u/53724080/Circuits/Oscillators/Coupled_Resonators.jpg The waveforms decay,...

Cool visual patterns: https://dl.dropboxusercontent.com/u/53724080/Circuits/Oscillators/Coupled_Resonators.jpg The waveforms decay, which must be some Spice setting. Ideal resonators wouldn't lose energy. Gear integration is much worse than trap. -- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology...


dremel phemt

Started by Anonymous in sci.electronics.design1 year ago 11 replies

I'm trying to do some DC/pulse testing on a phemt, partly to validate a Spice model. The RF data sheets are mostly useless for time...

I'm trying to do some DC/pulse testing on a phemt, partly to validate a Spice model. The RF data sheets are mostly useless for time domain use. The danged thing keeps oscillating on a regular surfmount adapter, and that makes measurements weird. So I hacked this. https://www.dropbox.com/s/s8i90zlrgxdrzu2/Phemt_Dremel_1.jpg?raw=1 SOT-143 is about my resolution limit for handheld dremeli...


LTSpice simulator of my oscillator is far from reality; bad models?

Started by Clifford Heath in sci.electronics.design9 years ago 25 replies

Folk, Thanks to some good help here in the past, I have a nice clean oscillator (for my new fox transmitters), but I'm having trouble with...

Folk, Thanks to some good help here in the past, I have a nice clean oscillator (for my new fox transmitters), but I'm having trouble with the LTSpice simulation at higher frequencies. I'm assuming that the Intersil Spice model for the CA3046 is bad, and I know JT has a better one. Anyhow, I have two questions about the attached LTSpice schematic. 1) When I set it to 30MHz, LTSpice ...


Two questions about LTSpice

Started by Marco Trapanese in sci.electronics.design10 years ago 23 replies

Guys, I know most of you are experienced users of spice here :) Two short questions, I've already RTM without find the answers. - I need a TIP...

Guys, I know most of you are experienced users of spice here :) Two short questions, I've already RTM without find the answers. - I need a TIP 122 model... where I should look for? - worst-case scenario: I set the tolerances of my resistors. How to run a simulation to get the worst-case? I'm talking about the maximum span of selected traces when components reach their end values. Tha...


Spice problem

Started by John Larkin in sci.electronics.design9 years ago 25 replies

https://dl.dropboxusercontent.com/u/53724080/Circuits/Amps/LT1028N.jpg LT1028 works, but LT1028N, the one that brings out the comp pin,...

https://dl.dropboxusercontent.com/u/53724080/Circuits/Amps/LT1028N.jpg LT1028 works, but LT1028N, the one that brings out the comp pin, doesn't. -- 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 a...


SPICE model for photodiodes including transit time effects?

Started by Phil Hobbs in sci.electronics.design11 years ago 19 replies

Hi, all, Most of the time I just model photodiodes as current sources with parallel capacitances, and put in any deviations by hand...

Hi, all, Most of the time I just model photodiodes as current sources with parallel capacitances, and put in any deviations by hand afterwards. At the moment I have an application where I need to do rather better than that, to explore the tradeoff between speed, bias voltage, and quantum efficiency. (It may wind up with custom photodiodes.) The only thing I've found in the free literat...


LTSpice: how to simulate a current limiter?

Started by Piotr Wyderski in sci.electronics.design4 years ago 7 replies

Hello, in my sims I often need to simulate a soft-saturable current limiter, usually for AC. The exact construction of such a limiter is not...

Hello, in my sims I often need to simulate a soft-saturable current limiter, usually for AC. The exact construction of such a limiter is not important from the core circuit's perspective. As long as its I(U) is sigmoid or arctan-like, it's fine. What's the simplest way to express such a building block in Spice? Making it out of discretes every time adds considerable obscurity to the sim a...


Transformer/excitation coil for Armstrong oscillator

Started by Anonymous in sci.electronics.design4 years ago 11 replies

Could some electronics guru on this group please help ? I am trying to set up a SPICE simulation for an Armstrong oscillator. The problem seems to...

Could some electronics guru on this group please help ? I am trying to set up a SPICE simulation for an Armstrong oscillator. The problem seems to be with designing the transformer and/or excitation coil. Are there any good tutorials or related material online. Any hints/ suggestions would be of immense help. Thanks in advance.


LT Spice opamp a liittle weird

Started by John Larkin in sci.electronics.design6 years ago 21 replies

I was wondering about the power dissipation of an opamp, driving a sine wave into a mainly inductive load. See below. The first few...

I was wondering about the power dissipation of an opamp, driving a sine wave into a mainly inductive load. See below. The first few cycles current limit or something. I'm using UniversalOpamp2 with current limit 2 amps and rail=0. This opamp isn't documented in the HELP, or much anywhere else. Peak current is under 700 mA, so why is it clipping? Higher supply voltage helps. ...


LT spice, leakage inductance

Started by John Larkin in sci.electronics.design5 years ago 227 replies

I'm simulating a flyback switcher and noticed that any K < 1 in the transformer radically slows down the sim, which is annoyingly...

I'm simulating a flyback switcher and noticed that any K < 1 in the transformer radically slows down the sim, which is annoyingly slow already... 90 seconds to sim 60 ms of startup and a little pulsed load blip. Maybe 6:1 slower with a little leakage inductance. So I only include leakage inductance to tweak the snubber. -- John Larkin Highland Technology, Inc picosecond


AD633 Spice Model Now Available

Started by Jim Thompson in sci.electronics.design4 years ago 4 replies

On the Device Models & Subcircuits Page of my website you will find a new post... AD633_JT.zip A Rudimentary Behavioral Model...

On the Device Models & Subcircuits Page of my website you will find a new post... AD633_JT.zip A Rudimentary Behavioral Model of Analog Devices AD633 Analog Multiplier suitable for most transient analysis situations. However Noise, CMRR and Feed-Thru are not modeled. ...Jim Thompson -- | James E.Thompson ...


Twisted Pair

Started by Jim Thompson in sci.electronics.design9 years ago 107 replies

Anyone have a decent Spice model for a twisted pair... lossy, not the ideal model in circulation? ...

Anyone have a decent Spice model for a twisted pair... lossy, not the ideal model in circulation? ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 S...


another LT Spice question

Started by John Larkin in sci.electronics.design9 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...