hybridfree/eevblog-posts huggingface dataset:
precision +5V and +10V box - Page 1
Forum section: electronics / projects

author: whitevamp
author_rank: Regular Contributor
timestamp: July 18, 2016, 04:19:44 am
content: Hello all.well the +5V is not to precise, but works for what i wanted it for.so after seeing Dave's vids here a month or two back, I decided to try and get back in to doing hobby electronics, and try and remember every thing. its been 9yrs since i did any electronics, as well as having memory issues.so after trying to figure out what all i had, and watching some vids and some reading, i decided to make a precision ref box so i could check my DMM ( recent flebay acquisitions. ) with it, yeah it might be over kill but its what i had laying around. and this is after failing to repair my fluke 8502a, witch i made worseok enough with all the ramblings.so i wound up having a lt1021-10 ±0.05%, and a lm340t-5 ±2%, then i found a project box i still had, and all the other goodies for this little project.well it looks like the 3DMM's are in speck. at least i didn't wast my $$ on them from flebay.the test pin/stud there on the right in the middle I am using it for all of the grounds.the wall wort that i had laying around, and decided to use says its a 12vdc so i thought ok great that should give me enough over head for the lt1021. so i decided to plug it in and see if it was any good and check voltage on it, and well guess what the sticker lies its not 12vdc its 17.5vdc.. sorry no pick of the out put from the wall wort.

author: SeanB
author_rank: Super Contributor
timestamp: July 20, 2016, 05:21:55 pm
content: I did the same, just used a 10V reference only. Like you, I made it out of what was to hand, so the sockets are not red and black but blue and yellow. Did buy the AD581KH, so it at least is 10V.Power supply was an old DECT phone power supply, which had a transformer with 2 9VAC secondaries in it, and gave 9VAC and 5VDC to the phone. Took it and connected the secondaries in series, so I now had a 25VDC rail, and replaced the 470uF 16V electrolytic with a 470uF 35V one, taken from an old board. Then replaced the 7805 with a 7815 so I had a 15V supply.Used the original cable to connect the power supply to the reference, so it would run cool. Put it in the casing from another small wall wart, it was close to hand, and I had a surplus of those KXT9001 power blocks at the time. Runs all the time, and currently showing the UT61E is in calibration, as it is showing 10.000V now.

author: whitevamp
author_rank: Regular Contributor
timestamp: July 21, 2016, 02:23:20 pm
content: @SeanByeah, why bother buying something if you can make something work that you all ready have on hand.I have been thinking of making a cc cv power supply with all the parts i have laying around. but not sure.
Precision capacitor - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: November 29, 2019, 07:57:46 pm
content: Hi,couple of questions...1) is there such thing as a low noise capacitor? If so what type?2) separately, I am looking for capacitors in the range 10nF to 100nF (10V) with the tightest tolerance and thermally as stable as possible (but very tight tolerance has the priority). I am aware of C0G/NPO at 1%, is there anything better?Thanks

author: Colt45
author_rank: Contributor
timestamp: November 29, 2019, 08:04:40 pm
content: If you want better than 1% you want a standard and not a capacitor.If your circuit needs better than 1% perhaps you need to rethink it a bit.Try silver mica, though unlikely to find better than 0.5% in that range. (and anything bigger than a few hundred pF will be expensive!)

author: tggzzz
author_rank: Super Contributor
timestamp: November 29, 2019, 08:41:24 pm
content: If you can wait 2 months, you can get the long awaited TAoE x-Chapters.According tohttps://x.artofelectronics.net/the-book/table-of-contents/the section "1x.3 Capacitors" will probably have usefiul information. If you can't wait for that, there is useful info in TAoE.

author: Gyro
author_rank: Super Contributor
timestamp: November 29, 2019, 08:58:35 pm
content: Is this a one-off or quantity requirement (from the context, I'm guessing one-off).You can still pick up former Soviet era hermetic close tolerance Silver Mica and Polystyrene caps on ebay for relatively little money, and in larger values than you can find here.

author: tggzzz
author_rank: Super Contributor
timestamp: November 29, 2019, 09:09:58 pm
content: Quote from: ricko_uk on November 29, 2019, 07:57:46 pmSo, you think an accurate capacitor is thesolutionto yourproblem. It may be, but if we knew your problem, we might be able to suggest better solutions....In other words, don’t ask “Can you give me a lift into town?” Do ask “Can you give me a lift into town, so I can replace my broken frobnitz?”. The answer might be “There’s a spare frobnitz in the attic”, thus saving time, money, the environment – as well as making some space in the attic.
precision capacitor? - Page 1
Forum section: electronics / projects

author: heathkitman
author_rank: Contributor
timestamp: May 26, 2013, 10:42:15 pm
content: Is there such a thing as a precision capacitor?I want to get a capacitor to use as a standard with my capacitance meters to check for accuracy and drift over time. What type of capacitor is the most precise / stable over time? I intend on using something in the 1.0 µF range.Thanks

author: PA4TIM
author_rank: Super Contributor
timestamp: May 26, 2013, 11:15:48 pm
content: Yes, there are standard capacitors. They are very expensive if you want them new. Used ones from General radio or HP are affortable and rather stable.But it depends on your capacitance meters what you need. For some ebay special everything will work as long as it is within 1% or so. If you want to check a GR-1620 it will be a whole different story.What meter, 3 or 4 terminal ?What range, do you need pF or uFAir capacitors are very stable, polyprop and mica too.My oldest ones are air capacitors from Philips and from the 30's. They are still very accurate although the two terminal connection makes it useless for calibration. ( 100-1000 pF)I have a HP decade that does 40pF to 1.1uF, that are mica and air caps. This is a three terminal and usable for normal LCR metersFor calibration I also have a GR standard capacitor that does 1 to 10 uF in steps of 1 uF. Has thee terminal connection.But I have a GR1620 and I used that to make a collection of standard caps ranging 1pF to 100pF with 6 digit resolution, some nF values and some uF values. I measured them also on some calibrated good quality (non-Chinese) LCR meters. So these are good enough for calibrating or checking handheld LCR meters. Made them from PCB, used micas and some (not used) high quality ceramics I got from some one and were made for high precision RF circuitshttp://www.pa4tim.nl/?p=3418GRhttp://www.pa4tim.nl/wp-content/uploads/2010/11/standaardcondensator.jpgone of the Philips

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: May 31, 2013, 09:44:36 pm
content: Quote from: heathkitman on May 26, 2013, 10:42:15 pmI got couple of these 0.5uF caps recently from seller on ebay who sells old Russian stockhttp://www.ebay.com/itm/0-2uF-0-5-250V-Precision-Polystyrene-Capacitors-2pcs-/200845492287?pt=LH_DefaultDomain_0&hash=item2ec353003f0.5% is pretty good for capacitors. They are bigger than they look on photo, but both were within 0.1% at room temperature according to my LCR meter (Agilent).Same seller has more nominations.in Russian means microfarad, and "," (comma) is used for decimal point.-Alexei.

author: BiOzZ
author_rank: Regular Contributor
timestamp: May 31, 2013, 09:50:40 pm
content: Quote from: heathkitman on May 26, 2013, 10:42:15 pmyeah i bought 4 different types of 0.1% caps for $10 each on ebay not to long ago from 100pf to 0.47u ... but be careful the leads, close metal and even small changes in temperature can throw off the measuring of meters ... with just 2 terminals use short, spaced out leads and use the same leads to test them all!
precision current source - Page 1
Forum section: electronics / projects

author: hemnath
author_rank: Newbie
timestamp: March 14, 2017, 05:42:11 am
content: Hey hi.. I have been following this forum from long time and this is my first post.I would like to design a variable precision current source of 0 to 25mA. Should I use howland current pump method or bipolar current source method?Out of curiosity, I would like to know how the high end multimeters will work? how they achieve that precision?I am aware of certain things like selection of components with very low temp drift, low offset, low bias current, high precision voltage source.Any reference circuit would be much appreciated?Thanks in advance.

author: hemnath
author_rank: Newbie
timestamp: March 14, 2017, 08:34:41 am
content: Does this circuit provides 0 to 25mA? Should I consider any other things?

author: Benta
author_rank: Super Contributor
timestamp: March 14, 2017, 09:47:54 am
content: Not trying to be pedantic, but that's a currentsink.

author: hemnath
author_rank: Newbie
timestamp: March 14, 2017, 10:06:51 am
content: Please check this circuit

author: danadak
author_rank: Super Contributor
timestamp: March 14, 2017, 11:47:49 am
content: Some questions -1) Absolute accuracy desired ?2) Resolution ?3) Transient response settling time to N bits ?4) Compliance range needed ?5) Control method, processor with LCD or just pot or ?Regards, Dana.

author: David Hess
author_rank: Super Contributor
timestamp: March 14, 2017, 02:14:10 pm
content: Quote from: hemnath on March 14, 2017, 05:42:11 amHowland current pumps are more useful when you need a bipolar current source. Their resistor ratio matching requirements are not conducive to high precision.Multimeters usually drive a current mirror at the positive supply voltage with a ground referred current sink which is essentially two of this circuit in series except that there is a way to make an operational amplifier current mirror without an external FET:http://www.linear.com/solutions/1563

author: mmagin
author_rank: Frequent Contributor
timestamp: March 15, 2017, 03:44:05 am
content: One of the easiest ways to achieve a reasonably precision current source in this range with widely available components would be a LT3092 and some fairly low-TC thin film resistors.
Precision Low-Voltage Function Generator - Page 1
Forum section: electronics / projects

author: jram112
author_rank: Contributor
timestamp: September 23, 2013, 08:32:49 am
content: I'm wanting to create a precision low-voltage function generator with isolated power supply. I only need sine and square waves with amplitudes between 10uV - 1V and frequency range between 0.1Hz-10kHz. This device will be used to calibrate biomedical hardware. It will also include differential and single ended outputs.This device is very similar to what I need, but is almost 600 USD:http://www.ecgsimulators.com/products/model-220-function-generator.I think I'd rather create one and share the design with everyone. However, I have aquired one of these for $75 and will be performing a Dave Jones' inspired tear down with my screwdriver and camera...."take it apart".My initial thoughts are to use a DDS chip like Analog Device's AD9800 series DDS >> then condition the signal with a LPF >> then use a precision single-chip voltage divider network to get lower voltages >> finally followed with a precision auto-zeroing opamps for buffering. Amplitudes will be controlled by the DDS chip output.This may be a horrible initial design, but that's why I need input from you guys. How would you guys design such a device?

author: fcb
author_rank: Super Contributor
timestamp: September 23, 2013, 08:58:38 am
content: Use an audio DAC.

author: dannyf
author_rank: Super Contributor
timestamp: September 23, 2013, 10:01:52 am
content: QuoteUp until the opamp part, that's what those $5 ebay DDS modules do.QuoteThe stock ebay dds module allows amplitude modulation via a small change, but probably not at your resolution / precision. A better approach would be to use an outboard pga. The 10uv-1v range is actually pretty wide and you may want to look into an analog pga rather than a digital one.
Precision PSU with Op-amp - Page 1
Forum section: electronics / projects

author: facumedica
author_rank: Contributor
timestamp: March 14, 2014, 11:26:15 pm
content: I made a very simple circuit that gives me 0.5mV offset with a common Op amp.I just want to know why Dave said that it could be unstable. The ic is a NE532. I only tested it on protoboard, but I am aiming to create a portable precision PSU (sounds familiar?)And I am able to get 0v!Other thing I wanted to know if powering a Op amp with non-simmetrical values is valid (e.g. -2 and 12).Thanks!

author: tree
author_rank: Regular Contributor
timestamp: March 14, 2014, 11:31:59 pm
content: Powering your op amp using asymmetrical supplies is fine as long as you don't exceed the maximum.

author: facumedica
author_rank: Contributor
timestamp: March 14, 2014, 11:49:36 pm
content: Cool! I am going to design an non-symmetric supply for itAny advices for the entire project?I am thinking about powering the microcontroller with 4.096v reference voltage, so the PWM math will be a lot more easier.

author: tree
author_rank: Regular Contributor
timestamp: March 15, 2014, 03:34:31 am
content: Quote from: facumedica on March 14, 2014, 11:49:36 pmOne of my projects uses a +25 and -5 rail just to allow the output to get to GND.A schematic would be very helpful. I would just advise that you get a discrete ADC because the internal ADCs to the uC aren't that great (they are not precise nor are they accurate), especially if you're really going for precision.

author: facumedica
author_rank: Contributor
timestamp: March 15, 2014, 06:00:48 am
content: What I am trying to make is a precision power supply with components that I have on hand, so It will be the first prototype and then if everything goes well I can "get more serious". Although, I don't really think I will be using it soon (I mean the precision won't be needed) because I am a student and I don't really need it (talking again about the precision not the supply itself), it's just a projectSome other ideas are:-GLCD-Oscilloscope-USB communication-Maybe GLCD and USB Oscilloscope (both options, not simultaneous)-Run on batteries :O-Remote control via bluetooth, so you can have it under the bench and control it with a smartphone.-The most important: LOW costI already have the GLCD, a PIC (which I think I fried the USB), some drafts of the voltage control and current limit which I tested and they seem to work OK.So I will keep working on it and write the updates and progress here
Precision PTC Sensor Measurement - Page 1
Forum section: electronics / projects

author: IuriC
author_rank: Contributor
timestamp: December 01, 2014, 06:06:28 pm
content: Hi,I'm designing a precision current source to bias a PTC sensor. My specs are:- 1mA current source- 0 to 200 ohms sensor range- minimum of 0.5% precisionTrying to fit it with components I have in my desk.I managed the R2 value with a combination of 5 resistors ( 2x 1k 0.1% + 33 ohm 1% + parallel of 2x 33ohm 1% = 2049.5 ohm ), and reached about +/- 0.37% error in Iref ( Vref is +/- 0.25%).The ADC I have is MCP3551 from Microchip (22bits; differential input)I need a little help to determine how much error is inserted by the ADC. Always just looked at the number of bits and voltage reference value, don't have a clue about what the others parameters means (e.g. integral non-linearity).I appreciate any help/suggestion about the circuit!Thank you in advance.

author: awallin
author_rank: Frequent Contributor
timestamp: December 01, 2014, 06:44:36 pm
content: What sensor are you using? 200 ohms seems low for a thermistor, and it'll probably never go very close to zero ohms?The common ones are 10 kOhm at roomtemp.To get resolution you'd need to push the constant current both through the thermistor and through a fixed reference resistor and compare the voltage drop. Or use a bridge circuit.

author: IuriC
author_rank: Contributor
timestamp: December 01, 2014, 06:54:41 pm
content: I read about 38~40 ohms in room temp. (28°C) and about 100 ohms in 200ºC.The sensor is embedded in a heat element, I don't know brand name / part number.

author: IuriC
author_rank: Contributor
timestamp: December 02, 2014, 12:29:29 am
content: I'm gonna take a walk through those links. Thanks alot for sharing!Also thank you for your suggestions!Iuri C.

author: Andreas
author_rank: Super Contributor
timestamp: December 02, 2014, 05:52:07 am
content: Hello,usually the cirquit for a RTD evaluation is built much simpler.see figure 43 in LTC2411 datasheet.http://www.linear.com/docs/1405You simply compare the voltage drop of your sensor with that voltage drop of a reference resistor which is supplied from a low noise supply voltage (or reference voltage).With your ADC you could probably built a voltage divider between reference voltage of the ADC and the RTD Resistor.Why using a current source with extra errors of OP-Amps and additional reference voltage?With best regardsAndreas

author: IuriC
author_rank: Contributor
timestamp: December 02, 2014, 04:23:36 pm
content: Quote from: Andreas on December 02, 2014, 05:52:07 amJust lack of experienceThis ADC seems to be a bit of overkill, but as I said in the first post everything has to fit with parts in my desk at this moment.I'll redesign the whole circuit using the information you guys gave to me. Thank you!Iuri C.
Precision resistors - Where from? - Page 1
Forum section: electronics / projects

author: IanJ
author_rank: Unknown
timestamp: February 21, 2014, 10:27:11 am
content: Hi all,After a number of years out of the picture I am slowly but surely I am getting back up to speed in regard to component suppliers and some of the newest technologies on the market..........but one question I'd like some help on is Precision Resistors.Back in the day I used to make good use of RCY55Y THP 1/4watt precision resistors.........but I notice that they are currently quite expensive, approx 75p+ via RS Components (UK) anyways.Any clues as to whats available now both in terms of THP and SMT. I've been used to 0.1% +/-15ppm but wouldn't mind something better......and preferrably 0805 SMT.Be nice to hear where others are getting their stocks from.Ian.

author: Rerouter
author_rank: Super Contributor
timestamp: February 21, 2014, 11:30:58 am
content: these are about $1 a pop on digikey but at 5 or 10ppm temp co they are hard to beat without really throwing down moneyhttp://www.susumu-usa.com/pdf/RG_RM_RGH_DATASHEET.pdf

author: EEVblog
author_rank: Unknown
timestamp: February 21, 2014, 11:50:02 am
content: Quote from: Rerouter on February 21, 2014, 11:30:58 amYes, I use those Susumu's in my uCurrent, very nice.

author: branadic
author_rank: Super Contributor
timestamp: February 21, 2014, 04:23:02 pm
content: You might want to risk an eye on MMU0102, MMA0204 and MMB0207 with 15ppm/K? They are half the price of RC55Y but surface mount.
Precision voltage reference - Page 1
Forum section: electronics / projects

author: unprintable
author_rank: Newbie
timestamp: December 30, 2018, 11:20:38 am
content: Hi!I am trying to build a precision voltage reference without the LM399 or even the LTZ1000.So i have made up a design and as i am quit a beginner i wanted someone to take a look at it, if all make sense and if i am getting a high precision and stability.The VCC might be around 9VDC and the reference output should be around 3.3V.The L1 is a 10uH inductor.Really appreciate feedback and any help!Thanks in advance!Regards,Alex

author: BFX
author_rank: Frequent Contributor
timestamp: December 30, 2018, 01:22:43 pm
content: Do you know this useful feature?(see img) You should definitely try it

author: unprintable
author_rank: Newbie
timestamp: December 30, 2018, 01:50:19 pm
content: Hi!As you might have read my initial sentence, i dont want to use these components as i want to find a different way to achieve a stable and precise voltage reference.Thanks.Regards,Alex

author: Gyro
author_rank: Super Contributor
timestamp: December 30, 2018, 02:04:14 pm
content: Sadly, we are sometimes afflicted by members who are unable to read past the middle of the first sentenceIf you're looking for something different, then you might want to try your hand at Alex's JFET reference...https://www.eevblog.com/forum/metrology/building-your-own-voltage-reference-the-jvr/

author: blackdog
author_rank: Frequent Contributor
timestamp: December 30, 2018, 02:48:07 pm
content: Hi AlexIt helps if you first tell what kind of reference you want to make.Different is not so useful to us to be able to help you.So which output voltage do you need?How much mA will the load be.At what supply voltage should the reference do its work?Over which temperature range should it be within how much PPM are stable.When I look at your schematic I get a bit dizzy, but I noticed one thing.Did you load the Opamp LTC2057 with 22nF! opamps should never be loaded directly with capacitors.And yes, there are some exceptions, but not important here.I would like to hear from you what your goals are.Kind regards,Bram

author: unprintable
author_rank: Newbie
timestamp: December 30, 2018, 02:55:38 pm
content: Hi!Ok here we go...- The exact voltage does not really matter, my primary target is a stable reference voltage- It's only purpose is for measuring and serving as a ref, so no "real" load will be attached to it- Supply range will be controlled by ADP7104ARDZ so it could handle max. 20V- Yea... PPM. The lower the better but i think (and hope) it will be around 10 to max. 25 PPM...?Thanks for your help!Regards,Alex

author: blackdog
author_rank: Frequent Contributor
timestamp: December 30, 2018, 03:11:00 pm
content: OKSome good chips.10VLT1021BCN8-10#PBFAD587KNZ5VLT1027BCN8-5#PBFLT1021BMH-5MAX6350CPAAnd the LT1236, LTC6655 in LS8 housingsKind regards.Bram
Precompliance Testing: ISN (Impedance Stabilization Network) - Page 1
Forum section: electronics / projects

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 26, 2015, 07:37:52 am
content: We've had topics on this forum before concerning EMC and impedance stabilization networks. Most often, the automotive LISN (line ISN).Equally important, but requiring a bit more finesse, is an ISN for signals rather than power. This must pass a communication signal with little degradation, while extracting the common mode signal for measurement.Rather than write an overly long and boring post about it, I decided to write an even longer and boringer web page:http://seventransistorlabs.com/Precompliance/index.htmlI'm pretty happy with it. If you're interested, I can make a PCB and instructions for assembly. The parts should all be commercially available...Bonus picture for filling space:Recognizable as one of the plug-in connectors. Nice "etching", wouldn't you say?Tim
Preferred PC DAQ software for an NI PCI-4472 - Page 1
Forum section: electronics / projects

author: DaJMasta
author_rank: Super Contributor
timestamp: November 06, 2019, 04:18:21 am
content: Found a good deal on a PCI-4472 (8 channel 104kS/s 24 bit ADCs) and built a little ITX computer around it so I could play around with a couple of triaxial accelerometers, but I'm trying to find the best software to be using for basic visualization, analysis, and recording. Is there anything free/open source that will get me started with this that isn't written for Labview or Matlab? I tried NI's DAQExpress as well, but while it supports the four channel 4474 and the two channel 4461, it doesn't appear to recognize my card. I've also tried Spectrum Lab, but it doesn't seem to recognize the card as an input source... I wonder if Audacity could figure it out.I'm looking for relatively basic display options including:Scope style waveform displayScope roll mode displayFFT display (with waterfall chart is a bonus)Recording and recall capabilityIdeally, also on all 8 channels at onceDoes anyone have a go-to program they use for this kind of thing? Or has anyone coded up their own to integrate with the VISA drivers? Free preferred, but I can pay a little if it's good software and not a yearly license.

author: jhenderson0107
author_rank: Regular Contributor
timestamp: November 06, 2019, 02:15:40 pm
content: I have the NI PXI-4461 which is a similar audio and vibration interface card, but packaged as a PXI Express rather than PCI plug-in card.I use a software package called Virtens Multi-Instrument, which is a full-featured tool providing all of the features you listed. It includes National DAQmx support, but can also be used to control ASIO and sound cards. It is usable only under Windows.I'm a C++ programmer and have located a handful of usable code fragments on Github and elsewhere on the web to access DAQmx hardware. If these would be of use to you, PM me and I'll share what I've located. When time permits, I intend to refine this code and add it to my instrument control library toolbox.

author: DaJMasta
author_rank: Super Contributor
timestamp: November 07, 2019, 04:38:36 am
content: That's an interesting option, it does seem to do what I'm looking for.... but matlab home is also priced right between the standard and full versions of Virtins Multi-instrument. May have to give the trial a look and see if it suits my purposes.I looked around a bit and found a freeware program claiming to be exactly what I was looking for called iodaq (http://www.iav-portal.com/index.php?nav=suiodaq&lang=en)... but I installed everything and when I load it I just see an empty console window and nothing happens... support seems to be nonexistent, so while I may try fiddling with it, it may just be a dead end.In the meantime, I've actually found that NI MAX included in the drivers actually has a display that will give you a roll mode chart or an FFT chart of a single channel for test purposes in the same menu you can run the card's self calibration, but it doesn't seem like any of their other free software wants to recognize it.
Preliminary thoughts about a project:  smart coexisting irrigation controller    - Page 1
Forum section: electronics / projects

author: Back2Volts
author_rank: Unknown
timestamp: September 14, 2017, 06:55:35 pm
content: We have a 16-zone programmable irrigation controller . It is from a reputable brand, multiple programs, remote control, etc... but it lacks flexibility for the "on demand" watering. The user interface at the control unit is a decade old technology: selector knob, 4 push buttons and small dim custom LCD. The remote works, but only allows to interact with a zone at a time, with to time feedback. The bottom line is that it would be nice to have a modern flexible interface, logging/reporting, mobile access, etc...So looking at options:1) Replace controller with one of the few mobile access irrigation control units on the market. Pros: probably does some of what we would like, better interface. Cons: a) The local servicing company (winter prep, spring start...) would not be familiar with it. b) It may not have all the whistles I could implement if I developed the software myself. c) There is no fun to it.2) Replace controller with my own design: Pros: many. Cons: a) same above servicing issue. b) Wife is a "practicing" Master Gardener, so the controller is "mission critical". Too risky!3) Hybrid system, with the existing controller as "dumb master" and my own designed as "smart slave", where the only prerogative of the master is to activate/override any one of the ports at any time. The new controller with full functionality as desired, plus awareness to relinquish control if it senses (rare) activity from the master. Old master remains as full online backup, alleviating stress from rework lapses on new controller.Option 3) is what I am exploring. I think of it as:1) Run the lines from master and slave through a bank of DPDT relays, with normally closed on the master side. I say relays because I thing it would be problematic to have two sets of TRIACs driving the same lines.2) New controller includes monitoring of the status of the master's ports to provide logging and turn off any other active line if required. I think of AC voltage sensing on all ports (OPTO ?) plus possibly a current sense transformer on the common line to valves from master side.3) Drive both units from same 24V AC class 2 transformer, replacing existing 24VAC/1A unit with 24VAC/1.5-2A to allow for new circuit load. Isolated DC PS for new digital side as well as isolation with the 24VAC lines. I am a bit worried about high voltage spikes on the valve lines due to storms, but at the end there is probably not much that can be done about it other than adding some TVSs.4) New system based on PSoC4/5 with 5" TFT/touch (keypad?). Possibly combined with RPi for local GUI and mobile support if doing this on PSoC becomes a bit challenging).All of this is very preliminary thinking. I will appreciate any comments and ideas.Tony
Pressure sensor for hot glue? - Page 1
Forum section: electronics / projects

author: bill_c
author_rank: Regular Contributor
timestamp: June 18, 2023, 08:12:37 pm
content: I need to measure the pressure of hot melt glue, looking for something cheap and reliable. Max operating temp 450F (232C), not sure what max pressure will be, but thinking 200PSIG. Do you know of an "Off the shelf" device (4-20mA, 0-10V, or serial) that works? My idea is a metal or PTFE diaphragm with push rod to a load cell. I'm using this for additional process feedback so calibration is not required, somewhat repeatable is required. I can fab, machine, and adapt just about anything for this, but would like to keep sensing face between .5" to 1" diameter since this will be attached to a 2" pipe.Thanks.

author: amyk
author_rank: Super Contributor
timestamp: June 18, 2023, 09:09:32 pm
content: Not sure what you consider "cheap", but look for "melt pressure transducers" used in plastic injection molding.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: June 19, 2023, 12:19:32 am
content: Look for a zero dead volume pressure transducer in your temperature range.

author: bill_c
author_rank: Regular Contributor
timestamp: June 19, 2023, 02:48:33 am
content: Thank you! Those terms find pretty much just what I am looking for.
presure sensor - Page 1
Forum section: electronics / projects

author: Zedy
author_rank: Contributor
timestamp: May 27, 2012, 06:08:55 pm
content: Good day!Does anyone know what kind of sensors are used to detect drivers in Red Bull velo minidrome? (You can see them in this video)Perhaps someone knows any similar sensor solutions. I'm creating time control systems for copy of the Red Bull mini velodrome, but have a major problem with the sensors. The ones I use are improvised and works well, but wore out very quickly. So I would like to know if there is something commercially available.

author: SeanB
author_rank: Super Contributor
timestamp: May 27, 2012, 06:34:30 pm
content: Are the sensors the white stripes across the lane? You might look at getting either a thin flat tube and using a fast pressure sensor to detect the wheel contact with a sealed tube, or use a piezoelectric cable, which generates a voltage into a high impedance input proportional to the mass of the wheel. If it is meant to be integrated into the surface then a flexible tube embedded in the top layers, compatible with whatever resin you are using, will give a pressure pulse as the track deforms. A small pulse, but measurable and reasonably accurate time wise.Otherwise a linear sensor on the central pole and a light source outside the track can be used ( with IR emitters and an appropriate IR filter on the sensor) as a simple sensor, though it will be sensitive to disturbance.
Pretty awesome sight - Page 1
Forum section: electronics / projects

author: madshaman
author_rank: Frequent Contributor
timestamp: July 05, 2013, 07:55:02 pm
content: Hi, I'd imagine someone's posted about this site before (maybe even one of curators?), but I just discovered it today browsing the web for info on RF filter design:http://www.hparchive.comThese look like they're FULL of goodies:http://www.hparchive.com/bench_briefs.htm
Pretty scope pictures - Page 1
Forum section: electronics / projects

author: tnt
author_rank: Regular Contributor
timestamp: April 27, 2011, 07:58:11 pm
content: Hi,I wanted to post a few nice pictures just for fun and also to remind that what you use to probe can be very important.The signal in question is a USB 2.0 hi-speed IDLE packet between my laptop and a USB stick. It's being probed at the usb stick end, after a usb extender cable.The equipment used is :* DSO-X 3034A (350MHz)* Passive probe N2890A 10:1 500MHz 10Mohm 11pf* Active probe 1158A 10:1 4GHz 100k 0.8pfFirst a reminder of how ground connection matter !Both captures are with a passive probe, the first one using the normal ground lead/alligator and the second one uses the ground 'spring' to have a very short connection.Then a few close up shots comparing the passive (on the left) and active probe (on the right):As you can see it doesn't seem to actually make that much of a difference in this case. The eye seems smaller with the active one but I think it's actually closer to the truth, it is also less "woobly" that with the passive probe (flatter top, less ringing).If you have cool pictures of nice measurements, please post them :p

author: Leo Bodnar
author_rank: Frequent Contributor
timestamp: April 28, 2011, 11:45:30 am
content: Quote from: tnt on April 27, 2011, 07:58:11 pmExtender cable is USB-illegal so you results are not comprehensive

author: Unknown
author_rank: Unknown
timestamp: April 30, 2011, 02:04:59 pm
content: Quote from: tnt on April 27, 2011, 07:58:11 pmThe difference between active and passive probes would probably be much larger with a longer ground lead. Because of the lower input capacitance of active probes, the inductance of the ground lead is much less significant. It would also be larger with a high source impedance, since the high input capacitance of passive probes represents a very low impedance at high frequencies (see the input impedance vs frequency graph in the data sheet).

author: tnt
author_rank: Regular Contributor
timestamp: May 02, 2011, 06:06:22 pm
content: Yes that's true.Actually they do put that in the "feature" list : "signal browsing". You can just have a long lead and view fairly ok signal up to a few hundred MHz without issues. For AC signals like oscillators and such, NO ground connection at all even works pretty well if you just want to have an idea of what you're probing(obviously the DC components is not there ...).
Prevent mains plug from "charging" battery - Page 1
Forum section: electronics / projects

author: staze
author_rank: Frequent Contributor
timestamp: November 16, 2013, 08:13:52 am
content: All,So, my son has a vibrating lounger (he's 3 months) that runs on 3xC (1.5V) batteries... and obviously it chews through them pretty fast (Fischer-Price must own a big share of Duracell and Energizer). I'd like to add a DC jack, which is simple if you just wire it in, or use dummy batteries, but I think that's a hack. I'd like to add a jack, and make it "safe" incase there's also batteries installed in the unit, not have them blow up from being "charged" by the wall connection, or have the device get twice the voltage it should. Obviously the latter could be fixed with an LM317 set for 4.5V, but what about the former? Would guess just a diode between the batteries and the DC jack, but I thought I'd ask if anyone has a solution I'm not thinking of.Or, maybe I'm tired (read, 3 month old) and it can be done with just a diode and a properly sized wall wart. I think I still need a regulator, or zener, or something to prevent accidentally giving the unit 9V if it had both batteries and the wall wart connected.Thanks!

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: November 16, 2013, 08:16:59 am
content: Most DC jacks are switched.http://www.ebay.com.au/itm/5-5-mm-x-2-1mm-DC-Power-Jack-Socket-Female-Panel-Mount-Connector-HP-/161112814814?pt=AU_CablesConnectors&hash=item25831274deyou plug something in, it disconnects the batteries...

author: staze
author_rank: Frequent Contributor
timestamp: November 16, 2013, 08:22:31 am
content: oh, fine, be that way.

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: November 16, 2013, 08:25:21 am
content: Go to bed!
Primary (eg USB) and Auxillary (eg, Battery) Power Steering IC? - Page 1
Forum section: electronics / projects

author: sleemanj
author_rank: Super Contributor
timestamp: October 01, 2013, 11:54:07 am
content: Short version: does anybody know of an IC that does something like the LTC4412, but which is closer to "jellybean level" pricing.Long version: this seems like something that there should be ICs for, simply to handle disconnecting one DC power supply when another DC power supply becomes available (or vice-versa), classic example battery backup, but without any charging.In it's most basic form, an ideal diode.It just feels like this is a problem that should have been well and truly packaged into an IC (controlling a single FET). And of course, it has, in the LTC4412/4414, but the pricing of this part is not very attractive, for what seems like it should be a really common thing.

author: dannyf
author_rank: Super Contributor
timestamp: October 01, 2013, 12:06:11 pm
content: I am sure that you can make an ic for it but a simpler version would use a diode (a mosfet configured as a diode).

author: sleemanj
author_rank: Super Contributor
timestamp: October 01, 2013, 01:28:33 pm
content: Yeah, it can be done discretely of course, this is what I came up with (ignoring specific parts, probably needs a cap, and it almost certainly has some stupid noob mistake that would stop it working).But it just seems like something that should be out there in a ready-to-roll package.

author: Frant
author_rank: Regular Contributor
timestamp: October 01, 2013, 11:28:21 pm
content: Quote from: mojo-chan on October 01, 2013, 01:47:33 pmHow about the TPS2115A?

author: zapta
author_rank: Super Contributor
timestamp: October 02, 2013, 05:48:40 am
content: Quote from: Frant on October 01, 2013, 11:28:21 pmLooks good to me. Contains the power mosfets, not just the detection and drive, provides low resistance also both input (as opposed to a OR diode on one input) and less expensive. Is there a catch?

author: marshallh
author_rank: Unknown
timestamp: October 02, 2013, 05:53:43 am
content: I've designed TPS2111APWR into some stuff. It works up to 1A, adjustable current limit set via resistor. Saved me from blowing up some boards due to manufacturing defects. Works just like you'd expect.$0.98 @ 100.

author: scott216
author_rank: Regular Contributor
timestamp: October 20, 2013, 10:58:46 pm
content: I asked a similar question on the Arduino forum and ended using a mosfet and a couple schottky diodes. Here's the link:http://forum.arduino.cc//index.php?topic=185144.msg1371898#msg1371898I used it to switch between power coming from my FTDI cable or USB cable.
Primary Ground and Secondary Ground of Audio Transformer - Page 1
Forum section: electronics / projects

author: joersam24
author_rank: Contributor
timestamp: May 04, 2012, 02:34:12 am
content: Hi to all,I just want to ask regarding the problem I encountered in our PSTN Telephone with interface to tablet PC project. This is the case, when the tablet PC is powered only by battery PSTN calling is okay. However, if the charger is connected to the tablet, there is a noise that occurs during telephone call. We used an audio transformer as an isolation between telephone chip and tablet PC. When I tried to connect the primary ground and secondary ground of audio transformer the noise caused by the charger disappeared..Any idea why this happened? I don't think the noise was caused by ground loops because the two grounds are isolated by an audio transformer..And one thing.. Primary ground and secondary ground of audio transformer should not be connected right?

author: IanB
author_rank: Super Contributor
timestamp: May 04, 2012, 02:39:19 am
content: You already asked this question in thisother thread. It's better to keep that thread going than start a new one.
Primary Lithium battery safety circuit - Page 1
Forum section: electronics / projects

author: Hast
author_rank: Newbie
timestamp: April 03, 2025, 08:09:17 am
content: HiI want to make a safety circuit for primary Lithium batteries (Li-socl2).The product drives a small motor that can peak at a bit above 2A when it hits the end stop.If the cells are below 2.3V I want to turn them off so they do not over discharge or can’t run the product correct.But when the battery is loaded the voltage drops and I do not want a temporary voltage drop to shut off the battery.This is why I have added resistor (R104) and a large cap (C100) to get a time delay before latching the output MOSFET.I have tried to Googling some safety circuits for Li-socl2 but the google-fu is not with me.I have added some notes in the schematic with questions.

author: BadeBhaiya
author_rank: Regular Contributor
timestamp: April 04, 2025, 01:12:17 pm
content: Li-socl2 primary cells are typically have very high internal resistance. There is no way, one can supply more than a few hundreds of mA. The cell must have a 20F or something similar supercap in parallel, right?

author: Hast
author_rank: Newbie
timestamp: April 07, 2025, 08:01:22 am
content: Yes, if I understand correct it is recommended to have a super cap in parallel to help so the voltage droop do not become so high during high currents but not a must.Also they need to be depassivated regularly.There are cells that can handle "high" peak currents, Saft LSH 14 batteries can handle 1300 mA continuous and 2000 mA peak.I only need to run the motor for like 3-4 seconds then go back to sleep, so a low self-discharge current is a must.The motor draws about 150-200 mA and when it hits its end stop it peaks at 2A and stops.The questions I have is if I must have diodes in parallel with the cells and if I must have a diode in series to protect against reverse polarity when the device will never have an external power source?The parallel diodes leak a small amount lowering the shelf life and the series diode have a Vf I do not what to have.
Primary split with series "cable compensation" capacitor - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: April 08, 2024, 03:21:25 pm
content: I've been handed a part schematic of a circuit used to transfer power.The front end has something that confuses me immediately: A transformer with a split primary and a series capacitor Cs linking the primary coils.I gather 'Cs' is intended to compensate for the de-tuning effect of the cable from the sine-wave source.I do not see why the designers did not simply place 'Cs' in series with a single-winding primary.I began to enter the circuit into LTSpice (I do not yet have full information like actual values). Having done that, I am not much the wiser.My guess is the capacitor is for PFC (power factor correction).

author: moffy
author_rank: Super Contributor
timestamp: April 08, 2024, 10:28:21 pm
content: Just a brief comment, your coupling factors look very low for a transformer, are they heavily air gapped?, and remember that L1 and L2 couple to one another also. It is certainly symmetrical and is reminiscent of a resonant supply of some sort. The split coils remind me of an LVDT where two coils displaced are excited anti phase and a pickup coil measures the displacement/voltage but that is not a power but sensor application.

author: 741
author_rank: Frequent Contributor
timestamp: April 09, 2024, 07:11:59 am
content: Using K=1 for both stalled the simulation.The coupling factors 'had to be' 0.5 to get the simulation working. I decided that could be physically reasonable as only half the secondary is close to either of the primaries.It might be (?) I do not need L1 to L2 coupling because (assuming Zc is low), it's basically 'as if' there are one coil.I've slightly ammeded the above because it looks like there is an inductive load.
printbot build today and tomorrow. on Twitter! - Page 1
Forum section: electronics / projects

author: Teljemo
author_rank: Contributor
timestamp: January 02, 2015, 06:51:45 pm
content: For you that are interested and have Twitter.The feed will burn hot with pics and stuff..So get on i. And follow!Check out Workshop Projects (@InTheWorkshop):https://twitter.com/InTheWorkshop?s=09

author: zapta
author_rank: Super Contributor
timestamp: January 02, 2015, 11:32:57 pm
content: Too many pre conditions. Simplify.
printer cable issues - Page 1
Forum section: electronics / projects

author: p.larner
author_rank: Frequent Contributor
timestamp: February 29, 2024, 08:45:27 am
content: I have a hpcp-1515 laserjet printer,this is my second one as the toner transfer belt broke on the first one,anyway getting to the point,The first printer worked fine on the end of a 5m usb2 extension cable,this new one wont,it throws an unknown device error,it is ok on the normal printer cable tho,what can cause this,maybe a bad cap or resistor drifted on the printer io pcb?.

author: moffy
author_rank: Super Contributor
timestamp: February 29, 2024, 09:39:08 am
content: The fact it works on the shorter cable means the USB is OK, but 5m for a 480Mb/s connection, there is plenty of possibility for signal distortion, attenuation etc. Even though the spec says 5m is acceptable it's going to be dependent also on the devices and the cable. You also get printer to printer variations and model revisions so it's hard to tell. You could try a hub or repeater in between and two shorter cables maybe.
PRINTER EPSON L1800 FATAL ERROR CODE H51 - Page 1
Forum section: electronics / projects

author: quinoara
author_rank: Contributor
timestamp: July 02, 2018, 04:38:37 am
content: I have an Epson L1800 printer, which changed the new main board and new nozzle head, It was introduced the ID of the print head without any problem. Which indicates that I do not have communication problems. The adjustmen Program software works perfect.But when running in the appendix-Printer Information Check it gives me a fatal error code, which I can not identify. The machine turns on, it tries to move the head a little and the power LED remains flashing and does nothing. The optical sensor of the PF encoder remains on but the PF motor does nothing, I attach a photo of the errors shown by Adjustment Program.I thank you in advance for a little help.
printer issues - Page 1
Forum section: electronics / projects

author: p.larner
author_rank: Frequent Contributor
timestamp: December 18, 2023, 09:58:26 am
content: i have a hp coulor laserjet cp-1515n laser printer,it works fine on my win 7 64 lappy but no go on my in 10 desctop,seems driver issues,any idea how to make it work on win 10?.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 18, 2023, 11:08:10 am
content: a simple search at their site you would have found their drivers win 10 32 et 64 bit compatible they say ??https://support.hp.com/us-en/drivers/hp-color-laserjet-cp1510-printer-series/model/3422467if not try compatibility mode ... if not ............ sorry use it on win 7 only. it is microsoft wrong doing ... or use your win 7 lappy as a printer server / sharing the printer on a network

author: gbaddeley
author_rank: Regular Contributor
timestamp: December 18, 2023, 11:31:34 am
content: Try the HP PCL 6 universal printer driver. It allowed me to use a recent LaserJet on Vista!

author: p.larner
author_rank: Frequent Contributor
timestamp: December 18, 2023, 04:59:06 pm
content: ive already tried all the things mentioned,even trying to print a test page from my printers folder it says sent but just sits doing nothing.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 18, 2023, 05:52:00 pm
content: check the spooler settings had some in the past who would not output a sheet until there was a few in the queue ??