signal pickoff

Started by John Larkin in sci.electronics.design6 years ago 65 replies

I'm designing a high-voltage pulser, 1200 volts or so, and I'd like to pick off a divided signal for the customer to...

I'm designing a high-voltage pulser, 1200 volts or so, and I'd like to pick off a divided signal for the customer to monitor. https://dl.dropboxusercontent.com/u/53724080/Circuits/Resistors/Pickoff.JPG Rise/fall times will be a few us maybe. I'd like to have the pulse response be pretty good, so the capacitances matter. The OPA171 opamp and R2 have capacitance, roughly 4 pF total, ...


ASIC IP library to check out die usage

Started by Anonymous in sci.electronics.design5 years ago 10 replies

Hey So I am looking into an ASIC to move general parts into an ASIC to reduce costs It would include opamp, comparator, transistors...

Hey So I am looking into an ASIC to move general parts into an ASIC to reduce costs It would include opamp, comparator, transistors etc Before contacting a company that specialises in ASIC I would like to gain more insight I know IP libraries exist with building blocks like those mentioned above. How do I get started in getting libraries and a placement tool/program? Regards ...


Voltage to PWM

Started by George Herold in sci.electronics.design5 years ago 18 replies

Hi all, I want to make a V to PWM circuit. (For a servoed heater.) I drew a triangle wave into a comparator, and that seems simple enough. ...

Hi all, I want to make a V to PWM circuit. (For a servoed heater.) I drew a triangle wave into a comparator, and that seems simple enough. Though it will take a few IC for the triangle wave. (I guess I could use an opamp and dual comparator.) So I went searching for V-PWM IC's. Most are for SMPS controll, which seem overly complicated for what I want. I also want a fairly low...


positive response from noise input

Started by captoro in sci.electronics.design7 years ago 4 replies

Hello All, Making a project where I need to turn on a led when there is a glitch on my= RF C.B. Most often the noise I receive is on the...

Hello All, Making a project where I need to turn on a led when there is a glitch on my= RF C.B. Most often the noise I receive is on the negative side (-100mv to -2v) as s= een on the oscilloscope. I am using an opamp to amplify the voltage to usab= le level. What I need to do is to invert the negative noise so I get the po= sitive and negative voltage so I do do not 'miss' any spikes. I o...


Howland current pump question

Started by bitrex in sci.electronics.design7 years ago 28 replies

Is it normal for the op amp inputs of the Howland pump to not be at the same voltage? In all my experiments in LTSPICE with the "improved"...

Is it normal for the op amp inputs of the Howland pump to not be at the same voltage? In all my experiments in LTSPICE with the "improved" topology and grounded resistive loads, this seems to have been the case. The circuit obviously has both positive and negative feedback, but if the opamp output is not railed then I assume the negative feedback must be "winning." But if this is ...


Measuring high voltages

Started by TTman in sci.electronics.design7 years ago 9 replies

I have a circuit that generates a floating ( both sides) ~ +/- 1500V. The final output is generated by a standard diode cap multiplier block,...

I have a circuit that generates a floating ( both sides) ~ +/- 1500V. The final output is generated by a standard diode cap multiplier block, giving 1mA current. The +ve output is monitored via a 1G resistor into an opamp then an ADC. The negative output is allowed to follow the positive which is in a closed loop controlto set the output voltage. What is the best way to monitor the -ve ...


Optical noise

Started by Paul Colby in sci.electronics.design9 years ago 46 replies

Hi, This really isn't a circuit question but people here likely understand what I'm finding so confusing. I've built several AC coupled...

Hi, This really isn't a circuit question but people here likely understand what I'm finding so confusing. I've built several AC coupled photodetectors to play around with. Basic transimpedance amp using a 0.8 m^2 diode with 150K feedback resistor. The opamp is an old LM301 with 30pf comp cap. I've also added a small bypass cap on the feedback resistor to flatten out the r


OpAmp design - from theory to practice (Re-post)

Started by Francesco Zappon in sci.electronics.design5 years ago 4 replies

(Re-posted using a proper news provider, because i was told googlegroups is blocked by many on this list) Hello everyone, first post here....

(Re-posted using a proper news provider, because i was told googlegroups is blocked by many on this list) Hello everyone, first post here. I hope I do not break any rule; let me know if this is the case. Disclaimer: not native English speaker, forgive any mistake. My background: master degree in physics (with a few courses in electronics). PhD in electronics/physics, doing 99% of...


TIA stability

Started by bitrex in sci.electronics.design9 years ago 6 replies

I was looking over the documentation about TIA stability from TI here: http://www.ti.com/lit/an/snoa515/snoa515.pdf and have a few questions....

I was looking over the documentation about TIA stability from TI here: http://www.ti.com/lit/an/snoa515/snoa515.pdf and have a few questions. Am I correct in thinking that an uncompensated TIA where the pole formed by the feedback resistor and input capacitance lies outside the GBW (0 dB open loop gain point) of the opamp will be stable without adding compensation? For certain value...


opamps coming off the rail

Started by John Larkin in sci.electronics.design9 years ago 27 replies

I need to drive a mosfet in current-sink mode. It's similar to...

I need to drive a mosfet in current-sink mode. It's similar to this circuit https://dl.dropboxusercontent.com/u/53724080/Circuits/Current_Sources/Mirror2.JPG but V- will be ground and I'll run the opamp off +8 or +10 or something, whatever drive the fet needs to sink 150 amps. I'd prefer to not have a negative power supply. At zero requested current, I want the current to be really...


opamp power, railed

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

Some opamps pull a lot of unexpected supply current if they are railed. I'm doing a thing with an OPA171, nice little amp, but I'm using a...

Some opamps pull a lot of unexpected supply current if they are railed. I'm doing a thing with an OPA171, nice little amp, but I'm using a wimpy shunt regulator to make a -3 supply, and was concerned if the amps might bog it down. Turns out that it uses about 450 uA at 10 volts supply, and pulls *less* current as it rails in either direction. That's good news. It also comes off the ...


Spice Model for OpAmp Output Stage

Started by Jim Thompson in sci.electronics.design5 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


OT: Equation Solving

Started by Jim Thompson in sci.electronics.design5 years ago

In my development of a generalized OpAmp model with independent setting of GBW, Slew Rate and Input Transition Width I found myself hung on...

In my development of a generalized OpAmp model with independent setting of GBW, Slew Rate and Input Transition Width I found myself hung on solving the transfer function shown in green... for the value of VB at the right-most zero crossing. My in-PSpice Newton Solver barfed. Then I lit on the idea of using my new Most_Positive segme


Flyback vs half-bridge

Started by Phil Hobbs in sci.electronics.design8 years ago 160 replies

So, I'm goofing off playing with small switchers. (Well, not exactly goofing off, but there are somewhat more pressing tasks waiting....) As...

So, I'm goofing off playing with small switchers. (Well, not exactly goofing off, but there are somewhat more pressing tasks waiting....) As I said in George's thread, "Opamp w/ Vsupply > 36V", I built a small half-bridge supply with positive and negative voltage doublers. I'm not that keen on it, because (a) it uses a fair number of parts for what it does, and (b) it has a nasty ins


MSOP to SO8 adapter

Started by John Larkin in sci.electronics.design7 years ago 16 replies

This lets us drop another opamp into an LT1124 SO8 footprint. LT1124 has a nonstandard pinout, so few subs are...

This lets us drop another opamp into an LT1124 SO8 footprint. LT1124 has a nonstandard pinout, so few subs are available. https://dl.dropboxusercontent.com/u/53724080/PCBs/Z364_Adapter_2.JPG -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com


'7' precision opamps

Started by George Herold in sci.electronics.design4 years ago 16 replies

Hi all*, well I was trolling digikey for precision opamps... without a lot of success. (too many parameters) And then I remembered this table...

Hi all*, well I was trolling digikey for precision opamps... without a lot of success. (too many parameters) And then I remembered this table from AoE3. https://www.dropbox.com/s/b6ut1jk5cf54qbt/7-prec-opamp.pdf?dl=0 note: This is only the HV section, there's another page of low voltage ones. So I was looking for opamps with ~100uV max Vos and ~100 pA max bias current. (+/- 15 supp...


nice little opamp

Started by John Larkin in sci.electronics.design5 years ago 9 replies

http://www.onsemi.com/PowerSolutions/product.do?id=NCS2005 This is rrio, 8 MHz, 32 volts max supply. It seems to be c-load stable at 1...

http://www.onsemi.com/PowerSolutions/product.do?id=NCS2005 This is rrio, 8 MHz, 32 volts max supply. It seems to be c-load stable at 1 uF and up, ceramic or tantalum, which means it can drive bypassed reference rails and low-current power rails. It rails clean, so will work as a comparator, but above 20 volt supply the positive clamp gets a little strange. 40 cents each by the r...


Opamp frequency mixer

Started by bitrex in sci.electronics.design6 years ago 56 replies

So as a hobby project I'm thinking of building a tiny little theremin using some of those Soviet subminiature pentodes that are really cheap...

So as a hobby project I'm thinking of building a tiny little theremin using some of those Soviet subminiature pentodes that are really cheap on eBay. Unfortunately, it seems that the most complicated part of the project would be the frequency mixers, as I don't think they really made subminiature heptodes and a "proper" mixer would probably require two tubes. I'm thinking about going s...


Simulating Power Bandwidth

Started by Jim Thompson in sci.electronics.design7 years ago 19 replies

I'm trying to do a simulation to show power bandwidth for a (high power) OpAmp versus compensation capacitor. In the lab I would simply crank...

I'm trying to do a simulation to show power bandwidth for a (high power) OpAmp versus compensation capacitor. In the lab I would simply crank up the signal generator amplitude until the output became triangular rather than sinusoidal. Collect all the data for peak amplitudes versus frequency and then plot. Any ideas how I might do that automatically in a simulator, generating a family...


OpAmp design - from theory to practice

Started by Francesco Zappon in sci.electronics.design5 years ago 24 replies

Hello everyone, first post here. I hope I do not break any rule; let me know if this is the case. Disclaimer: not native English speaker,...

Hello everyone, first post here. I hope I do not break any rule; let me know if this is the case. Disclaimer: not native English speaker, forgive any mistake. My background: master degree in physics (with a few courses in electronics). PhD in electronics/physics, doing 99% of digital design. My last encounter with analog design: 10 years ago (ie: my knowledge is a bit "rusty").