LT Spice universal opamp

Started by Anonymous in sci.electronics.design2 years ago 5 replies

In universalopamp2, what does the "rail" parameter do? -- John Larkin Highland Technology, Inc The cork popped merrily,...

In universalopamp2, what does the "rail" parameter do? -- John Larkin Highland Technology, Inc The cork popped merrily, and Lord Peter rose to his feet. "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"


Optocoupler suggestions

Started by bitrex in sci.electronics.design3 years ago 28 replies

What are some optocouplers you like that would be good for designs where they're used in unusual ways, like that "HV Opamp" thing JL likes where...

What are some optocouplers you like that would be good for designs where they're used in unusual ways, like that "HV Opamp" thing JL likes where they're used as the "output stage" of an amplifier? Are any characteristics that I should look for in the datasheet that makes a particular coupler a better performer in an application where linearity is more important than high-speed switching...


little photo diodes and an opamp?

Started by George Herold in sci.electronics.design2 years ago 16 replies

The project seems to call for the smallest detectors. I'm buying a few each of 'all'* the little PD's from digikey. (I can share a list if...

The project seems to call for the smallest detectors. I'm buying a few each of 'all'* the little PD's from digikey. (I can share a list if someone wants... it's a mix of TH and SMD.) C_in between 1-3 pf when reversed biased. I don't see how it makes sense to bootstrap or cascode the PD**. So I was looking at opamps with small C-in. (Big thanks to H&H of AoE as always.) I've now g...


jelly bean op amp suggestion please

Started by David Eather in sci.electronics.design6 years ago 7 replies

hello, Just asking what everyone uses for a trouble free R-R (output), 5v opamp 1 to about 5Mhz BW. It would be nice if inputs were able to...

hello, Just asking what everyone uses for a trouble free R-R (output), 5v opamp 1 to about 5Mhz BW. It would be nice if inputs were able to go to GND and thats about it for extra requirements. I have some Microchip amps that are 'almost right' - but I would like to find other possibilities that have been found to be trouble free for breadboarding


another LDO

Started by John Larkin in sci.electronics.design9 years ago 199 replies

Seriously, I need another LDO for a new gadget. It needs to work down to maybe 1 volt drop, and needs to be very accurate,...

Seriously, I need another LDO for a new gadget. It needs to work down to maybe 1 volt drop, and needs to be very accurate, especially longterm drift and TC. How about this? http://dl.dropbox.com/u/53724080/Circuits/T680_LDO.JPG Joerg will be pleased to see a depletion fet. Jim will find something to whine about. It might be fun to power the opamp from the +10 rail, if I could p...


LT Spice powering opamps

Started by John Larkin in sci.electronics.design6 years ago 5 replies

I usually have a couple of "voltage" things off to the side, making +5 and -5 or whatever, and have each opamp with little doglegs on...

I usually have a couple of "voltage" things off to the side, making +5 and -5 or whatever, and have each opamp with little doglegs on its power pins, same net names. Somewhere I thought I saw a circuit where the opamps were powered by little boxes with "+5" or something inside, with no other supply needed. Does that work? If so, how do you invoke it? -- John Larkin ...


Current source circuit fail.

Started by George Herold in sci.electronics.design4 years ago 19 replies

I made this nice VCCS from a differential amp (Ina134), resistor and opamp (opa134) feedback. It was good to 40 or 50 mA. Bad...

I made this nice VCCS from a differential amp (Ina134), resistor and opamp (opa134) feedback. It was good to 40 or 50 mA. Bad ass-ci. gnd---RR---+--RR-----+ ||\ | +|-\ | Ina134 | > -(A)-+--Rset-+---output to gnd. +|+/ | ||/ /| | Vin--RR--+----RR--- < +-----+ \|


CV measurement

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

Hi all, I want to do some CV (capacitance vs voltage) measurements On some diodes and things. I drew up...

Hi all, I want to do some CV (capacitance vs voltage) measurements On some diodes and things. I drew up this, https://www.dropbox.com/s/tnn1mb4o41iqno9/DSCF0008.JPG Pretty much brute force. (I sometimes get the feeling that opamps are the only tool I know.) I don't really like putting the bias and modulation through the same opamp. Any other ideas? (I don't want to go the transfo...


Datasheet Jargon Translation Required

Started by Cursitor Doom in sci.electronics.design4 months ago 101 replies

Can some kind sould tell me what the following load of old cobblers from the datasheet of a FET opamp means in plain...

Can some kind sould tell me what the following load of old cobblers from the datasheet of a FET opamp means in plain English? ******************************************************************************** "As with most amplifiers,care should be taken with lead dress,component placement and supply decoupling in order to ensure stability.For example,resistors from the output to an input ...


Good week for chips

Started by John Larkin in sci.electronics.design4 years ago 9 replies

Phil might like this one: http://www.linear.com/product/LT6018 This is a 1 nv-noise-class opamp with a 1 Hz 1/f corner. It doesn't seem...

Phil might like this one: http://www.linear.com/product/LT6018 This is a 1 nv-noise-class opamp with a 1 Hz 1/f corner. It doesn't seem to be a chopper, but that may be hidden inside. Input noise current is fairly high. -- John Larkin Highland Technology, Inc lunatic fringe electronics


Opamps - everything

Started by Anonymous in sci.electronics.design5 years ago 35 replies

Jim Thompson wrote > Math ?? If you're only a user, you can write down all you need to > know about OpAmps in a couple of pages. > ...

Jim Thompson wrote > Math ?? If you're only a user, you can write down all you need to > know about OpAmps in a couple of pages. > > ...Jim Thompson I'd be very interested in that. So lets see what would need to be covered: The basic idea of what an opamp is and how closing the loop enables it to do all sorts. Understanding th


OpAmp Voter

Started by SRob...@SpamSucks.net in sci.electronics.design7 years ago 32 replies

I have three DC-5Khz, 0-5 V positive going signals. I'd like to select and = pass the highest of the signals, without diode losses. Using a...

I have three DC-5Khz, 0-5 V positive going signals. I'd like to select and = pass the highest of the signals, without diode losses. Using a microproces= sor is out of the question. Cost is a object and actives should be limited= to devices that can be second sourced.=20 This is for converting a RGB command signal to an intensity signal. Steve=20 =20


blowing up OPA277's

Started by George Herold in sci.electronics.design5 years ago 17 replies

Hi all, I'm prototyping this square root circuit. (I had a thread here maybe a year ago.) The circuit works fine in spice, but turning it on and...

Hi all, I'm prototyping this square root circuit. (I had a thread here maybe a year ago.) The circuit works fine in spice, but turning it on and off a few times.. (or something) is causing the opamp protection diodes to fail. (All of a sudden the inputs are spitting out DC voltages.) A circuit fragment looks like this, Vin----RRRRR-----+----more of the same...


TI opamp

Started by John Larkin in sci.electronics.design7 years ago 46 replies

Has anybody used this one? http://www.ti.com/product/lme49990 Sounds too good to be true. -- John Larkin Highland...

Has anybody used this one? http://www.ti.com/product/lme49990 Sounds too good to be true. -- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com


1/x function with op amps or multiplier or something else...

Started by Fibo in sci.electronics.design6 years ago 58 replies

Hello, I'm trying to figure out the best way to go about making a -1/x function in hardware. From googling around I see 2 methods, 1....

Hello, I'm trying to figure out the best way to go about making a -1/x function in hardware. From googling around I see 2 methods, 1. Inverting log -> Anti-log 2. OpAmp with multiplier in the feedback loop I have +/-5V rails available, and my input is from 0.4V to 2V (which should give me an output of (-2.5 to -0.5). All DC values. Can anyone point me in the right direction here, I'm


DC background subtraction

Started by George Herold in sci.electronics.design3 years ago 47 replies

Perhaps a silly simple question. I need to subtract off a 2.5V background from a few mV signal. I first think about a difference amp, or...

Perhaps a silly simple question. I need to subtract off a 2.5V background from a few mV signal. I first think about a difference amp, or instrument amp. But I wondered if there is any advantage to a simple opamp summing amp. (I'll add in -2.5 V) George H.


Low bias current opamps

Started by Jeroen in sci.electronics.design9 years ago 36 replies

I was playing today with a little ionization chamber amplifier, which is an exercise in high-impedance design. My usual business revolves around...

I was playing today with a little ionization chamber amplifier, which is an exercise in high-impedance design. My usual business revolves around wideband RF amplifiers, so this is unfamiliar territory for me. I selected an LPC661 opamp which has a specified maximum Ib of 4pA, but with a typical value stated to be 2fA. That's a very large difference, which, I guess, is motivated by the need...


Opamp power supply

Started by amdx in sci.electronics.design6 years ago 14 replies

Hi all, I'm about to build this detector/audio amp circuit. > http://www.crystal-radio.eu/diodedetector/endiodedetector.htm I want to run...

Hi all, I'm about to build this detector/audio amp circuit. > http://www.crystal-radio.eu/diodedetector/endiodedetector.htm I want to run it from batteries, I thought it was +/- 4.4v supply. I thought I was going to use 6 AA cells and center tap them, but maybe not. I just noticed it looks like it's +12 and -4.4v. First, does that make sense? Or could it be an error in the present


op-amp circuit wont work

Started by panfilero in sci.electronics.design10 years ago 38 replies

can anyone tell what I did wrong here? my goal is to measure current using an opamp, I need to be able to measure positive and...

can anyone tell what I did wrong here? my goal is to measure current using an opamp, I need to be able to measure positive and negative current, and I have these LTC2053 OpAmps available, but I'm trying to simulate what I'm thinking about doing in LTspice and I can't get any output at all.... I need to be able to see from 50uA to .1mA, which is a pretty big range (and I need this in positive...


200V amplifier

Started by maxascent in sci.electronics.design10 years ago 18 replies

I need an amplifier that can amplify a 5V p-p (range 5V to 0V) signal to 200V p-p (range 200V to 0V). The bandwidth needs to be at least 500...

I need an amplifier that can amplify a 5V p-p (range 5V to 0V) signal to 200V p-p (range 200V to 0V). The bandwidth needs to be at least 500 kHz. Does anyone know of a circuit or maybe an opamp that is capable of this? TIA Jon --------------------------------------- Posted through http://www.Electronics-Related.com