hybridfree/eevblog-posts huggingface dataset:
Improving Futaba key switches (BBC Micro Keyboard)? - Page 1
Forum section: electronics / projects

author: steve30
author_rank: Frequent Contributor
timestamp: July 20, 2017, 06:17:16 am
content: I have a couple of BBC Model B computers from the early 1980s. The keyboards have Futaba linear key switches. They can be quite difficult to type on as they are quite squeaky and bind up easily. Its a shame as the keyboard is otherwise very nicely made; the switches are mounted on a mounting plate, and it has lovely double shot keycaps.Is there any way of improving these switches to make the typing experience better? I don't know if they were originally like this, or if they have got worse with age.If you aren't familiar with these switches, watch these videos by Chyrosran22:Thankssteve30

author: AndyC_772
author_rank: Super Contributor
timestamp: July 20, 2017, 12:44:11 pm
content: The sounds and feel of the keys you describe is pretty typical, though you may have a bad example and/or be more sensitive to their apparent shortcomings than people tended to be when these machines were new. The BBC micro's keyboard was about the best around when the machine was being sold, and was well known as one of its best features.The Master keyboard was never quite as nice as the Model B, and it did always have a bit of a metallic 'ring' to it.I never had an Electron, though I remember it as being a definite step down from the B in a number of ways. It was always known as a cheap substitute for the Model B, and was never popular.You might be able to clean or lubricate the keys if you want to, but are you really going to do a lot of typing on a 30+ year old computer?

author: steve30
author_rank: Frequent Contributor
timestamp: July 20, 2017, 09:02:23 pm
content: I suspected the 'feel' might be original. The keyboard is well made, so I don't have any worries about it breaking. It'll probably be good for another 30 years at least.I'm used to IBM Model Ms and Cherry switches, so the feel of the BBC is a bit unusual to me. I won't be using it a lot, but I'll probably start writing some programmes on it more if the keyboard were nicer.

author: amyk
author_rank: Super Contributor
timestamp: July 21, 2017, 01:59:53 am
content: Lubricate the sliders.http://imgur.com/a/lhLqohas a lot of information.
Improving output noise on a DPS3003 power supply module - Page 1
Forum section: electronics / projects

author: DG2MMT
author_rank: Newbie
timestamp: February 09, 2020, 03:47:20 pm
content: Hi everyone,I had some really nice success improving the output noise of my DPS3003 based power supply and just want to share my findings.I recently got my first oscilloscope (!) and one of my first measurements was on the output of my power supply. And what I saw was not so good: ringing noise up to 900 mV peak to peak with a 30 Ω load and 12 V output voltage.After some testing with different parts I got it down to about 90 mV peak to peak, so I would say, this was a full success.What did I do?Adding a snubber to the switch-node with 2.2 Ω and 620 pF (150 pf || 470 pF)adding a filter to the output with a ferrite ring with 2 windings for + and - and a 100 nF capacitorAnd here some pictures:DS1Z_QuickPrint4.png: Output power supply 1 before modification.DS1Z_QuickPrint25.png: Output power supply 1 after modification.DS1Z_QuickPrint26.png: Output power supply 2 before modification.DS1Z_QuickPrint32.png: Output power supply 2 after modification.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 09, 2020, 06:01:48 pm
content: Looks impressive for such a small modification.
improving power supply stabilizer circuit question - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: October 25, 2024, 05:00:19 pm
content: Hello,I Have simulated the circuit with a certain source but still I have a section where there is a slope on -12V as if we need the pulse to happen later.How do you recommend to get rid of the slope shown below in the photo.LTspice files is attached.
Improving rise time - Page 1
Forum section: electronics / projects

author: Pack34
author_rank: Frequent Contributor
timestamp: March 14, 2017, 02:11:53 am
content: I have an odd issue with distortion on a high-frequency digital signal. The attached scope shot shows two complimentary clocks. I'm concerned with the rise time on the green signal.Both simply have a 15-ohm series resistor leading to the input gate on the destination. The cable is about six inches long.The device seems to be functioning as expected, but I just don't like the way that it looks. It makes me feel that this "working" may be a fringe case and that, in volume, the device will not function a good percentage of the time.The signal is a -8V to 3V clock originating from a MAX627 MOSFET driver. I'm using this driver as a level shifter due to the required negative voltage swing.Any tips?

author: Audioguru
author_rank: Super Contributor
timestamp: March 14, 2017, 02:30:39 am
content: I cannot see the settings of your 'scope. It is 500ns per division so the risetime is a whopping 800ns? the datasheet for the driver says 20ns with a 1000pF load so your Mosfets have an input that is about 40,000pF. Get Mosfets with a lower input capacitance or a driver that can switch what you have faster.

author: Someone
author_rank: Super Contributor
timestamp: March 14, 2017, 02:34:21 am
content: Driving some large mosfets? Looks just like you'd expect as you pass the threshold voltage:http://www.st.com/content/ccc/resource/technical/document/application_note/68/cd/c6/ab/ef/17/41/06/CD00003900.pdf/files/CD00003900.pdf/jcr:content/translations/en.CD00003900.pdf

author: Pack34
author_rank: Frequent Contributor
timestamp: March 14, 2017, 04:48:14 am
content: Input capacitance is rated at only 800pF.

author: ScottK
author_rank: Contributor
timestamp: March 14, 2017, 05:39:48 am
content: You are witnessing the "Miller plateau", caused by the amplification of the MOSFETs Cgd by the apparent voltage gain from gate to drain. I suspect you see it only at turn-on because your maximum gate drive voltage (3V) is closer to the MOSFETs Vth than your minimum drive voltage (-8V), so you are turning the MOSFET off harder than you're turning it on. It's also possible that your load doesn't pull the drain up until after the gate drive goes low. You only see the Miller effect if the drain voltage is changing.Google "Miller effect" and/or "Miller plateau" to learn more.

author: David Hess
author_rank: Super Contributor
timestamp: March 14, 2017, 06:14:45 am
content: The waveform is wrong for a 6 inch transmission line or cable so something else is going on.Is the MAX627 decoupled correctly at its supply terminals?What is the ground return path for the cable like?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 14, 2017, 07:11:19 am
content: What a peculiar voltage.GaN FET?Tim

author: Pack34
author_rank: Frequent Contributor
timestamp: March 14, 2017, 03:18:10 pm
content: Quote from: ScottK on March 14, 2017, 05:39:48 amYes! Thank you!
Improving Signal Fidelity For 10:1 High Impedance Scope Probes - Page 1
Forum section: electronics / projects

author: tggzzz
author_rank: Super Contributor
timestamp: March 11, 2015, 04:16:00 pm
content: All too often signal integrity aberrations are visible in digital signals displayed on an oscilloscope. Fortunately signal fidelity can be significantly improved by a simple homebrew 3D-printed accessory that can be retrofitted to any standard scope probe.The examples below use an HP10074C scope probe (150MHz, risetime <2.33ns, 15pF, 6inch/15cm ground lead) and Tektronix TDS340 100MHz digital scope. Without the modification, a fast digital edge incorrectly appears to “ring” with a half-period of 5.5ns (91MHz), 20% overshoot, 33% peak-peak amplitude, and 10s of nanoseconds duration:With the homebrew accessory the ringing is removed, revealing the undistorted waveform.There is a little ringing at 3.6ns (270MHz), 0.5% overshoot, 4% peak-peak amplitude and <5ns duration. Somepre-transition ringing is visible (even using a 1.5GHz HP10020A probe), but it isnot visibleon an equivalent analogue scope. Hence that ringing is probably an artefact of the scope itself.For more information, seeScope Probe Accessory Improves Signal Fidelity
Improving the FAU200 power supply - Page 1
Forum section: electronics / projects

author: bloguetronica
author_rank: Frequent Contributor
timestamp: January 30, 2019, 07:03:01 pm
content: Hi,I've decided to improve the transient response of the FAU200 power supply, essentially by adding a 2.2uF capacitor in parallel with R7. I didn't solved the overshoot issue, although I did solve the ringing. Probably, a 100nF capacitor would do, but a 2.2uF capacitor prevents the OPA705 from hitting the rails when the DAC output voltage changes.So, I've included some scope screenshots from before the mod and after. The measured points are the supply output, the OPA705 output before R7, and the net between R7 and the Q2 base. Also did some load tests by setting the FAU200 supply to 2V and by using a 10resistor as a load. You can see that the performance is much better.I think that the extra capacitor increases the phase margin and speeds up the response. Note that R7 is necessary for adequate short circuit current limiting. It prevents the OPA705 from being shorted in case of short circuit at the output.Kind regards, Samuel Lourenço
Improving the Re:load active load - Page 1
Forum section: electronics / projects

author: texane
author_rank: Regular Contributor
timestamp: April 23, 2015, 04:21:27 pm
content: Hi there,I wrote a small post about how I modified the Reload2 activeload to add programmability and reduce the amplifier offsetvoltage, leading to a lower load current:http://www.embeddedrelated.com/showarticle/775.phpI hope you will find it interesting, if not useful !Cheers,T.
Improving the speed response of the LM311's input stage. - Page 1
Forum section: electronics / projects

author: schmitt trigger
author_rank: Super Contributor
timestamp: May 07, 2020, 03:28:14 pm
content: Many moons ago, I barely remember that in an ancient National Semi app note or datasheet, that one could significantly improve the LM311's input stage slew rate, by tying the both strobe/balance pins to +V.Analyzing the attached equivalent circuit, it is easy to see why. The PNP input stage Q1,Q2 is fed by a constant current source generated by Q5, with its associated resistors R1 and R2.Tying up the balanced pins to V+ effectively places R3,R4 in parallel with R1,R2. The end result is that the current fed to the input stage increases about five times, which should have the benefit of a proportional increase in its slew rate.Unfortunately, the newer datasheets do not mention anything related to any response speed improvement. The datasheets do show that the input bias current increases in this configuration, as it should. But that's it.So what do you guys think? Is my assessment correct?

author: SiliconWizard
author_rank: Super Contributor
timestamp: May 07, 2020, 03:39:49 pm
content: Yup. I think so.

author: David Hess
author_rank: Super Contributor
timestamp: May 08, 2020, 03:03:33 am
content: I remember reading the same thing about increasing the LM311's input stage current but I never had a chance to make use of it.

author: Zero999
author_rank: Super Contributor
timestamp: May 08, 2020, 12:00:50 pm
content: I wonder how well it would work with capacitors? That should boost the high frequency response, whist leaving the DC bias unaffected.

author: schmitt trigger
author_rank: Super Contributor
timestamp: May 08, 2020, 01:29:05 pm
content: Wow!That is one clever idea Zero999.

author: SiliconWizard
author_rank: Super Contributor
timestamp: May 08, 2020, 01:51:47 pm
content: Quote from: Zero999 on May 08, 2020, 12:00:50 pmWorth a shot!

author: magic
author_rank: Super Contributor
timestamp: May 08, 2020, 02:01:04 pm
content: Wouldn't that merely increase output impedance of Q5,Q6 current sources?I think the whole purpose of the original circuit was to increase precisely the DC bias of the input buffers, for the sake of beta/fT/whatnot.

author: schmitt trigger
author_rank: Super Contributor
timestamp: May 08, 2020, 07:42:26 pm
content: An alert reader in another forum mentioned that there is an old National Semi app note (AN-41), originally written by Bob Widlar back in 1970.It is still available in TI's website, but a little difficult to find as they have renumbered all of the National Semi's app notes.There is a paragraph hidden among the couple thousand word note, which mentions precisely the concept of input stage current rising.I have attached the app note and highlighted the relevant information.
Improving Thermal Performance?  - Page 1
Forum section: electronics / projects

author: jpanhalt
author_rank: Super Contributor
timestamp: February 27, 2020, 12:11:15 pm
content: Boron nitride (BN) is an exciting thermally conductive, electrically insulative material. It is fibrous and highly anisotropic w.r.t. thermal conductivity. Thermal conductivity along the axis of the fibers is 400 W/m*K (gold = 315W/m*K). Perpendicular to the fibers, it is at least 2 orders of magnitude less. There are lots of research papers from China and South Korea related to using it as a filler for epoxy to improve its thermal conductivity, particularly for IC encapsulation. As an epoxy filler, it works well but may require pretreatment (e.g., silyation) to avoid interface losses (e.g, from air). When mixed with aluminium oxide (Al2O3), it seems to work even better. The spherical particles of Al2O3 help align the BN particles to facilitate thermal conduction.Arctic Silver sells a BN-filled/Al2O3 epoxy thermal epoxy:https://www.amazon.com/gp/product/B0009IQ1BU/ref=ox_sc_act_title_1?smid=AKFWYWVZ484P5&psc=1The TDS claims a thermal conductivity of 4 W/m*K. That is quite high for an epoxy. I am interested in improving the thermal performance of a MSOP-10 package, specifically the Microchip MCP73833/4.Does anyone have experience using a thermally conductive adhesive with that chip to increase its charging capability to 500 mA without having thermal regulation cut-in.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 27, 2020, 01:03:23 pm
content: Sure:1. Reduce supply voltage (use a tracking regulator?)2. Reduce chip or ambient temperature (or max amb spec if this is an extreme case condition)3. Add thermal vias, use heavier copper, multilayer PCB4. Heatsink on topmaybehelps but the package thermal resistance isn't specified5. "Doctor, it hurts when I do this!" "Then don't do that." Get a bigger/better chip!Wait, what the hell chip are you using, there is no MCP7383... Did you mean 73831?There are also thermal pads with 5, even 10 W/(m.K) with a squishy durometer that a spring-loaded heatsink can conform around the parts. That'll do as well as the epoxy you describe, without the mess.You didn't mention any restrictions on your present case, so there are a huge number of possibilities, that hold much greater promise, than simply trying to sink the heat out.Tim

author: jpanhalt
author_rank: Super Contributor
timestamp: February 27, 2020, 01:17:02 pm
content: My typo on the chip -- missing a "3". Actual chip will be the MCP73834 (not MCP73833).MCP73833/4Had considered the MCP73831 but the MCP73833/4 has better heat performance.

author: jbb
author_rank: Super Contributor
timestamp: February 27, 2020, 01:18:47 pm
content: Yeah, it’s better to avoid the waste heat. I had a lot of trouble a while ago with a product warming up it’s own battery to the point it wouldn’t charge.If you must leave the chip the same, do consider ways to get the heat from the PCB to the outside world.
Improvised 1.25mm pitch to 2.5mm connector? - Page 1
Forum section: electronics / projects

author: lpc32
author_rank: Frequent Contributor
timestamp: January 24, 2021, 08:38:45 pm
content: Any ideas how to hack a stable 1.25mm pitch connector to 2.5mm?I don't have much readily available.From the 4p on the left, to something like those on the right:

author: Ian.M
author_rank: Super Contributor
timestamp: January 24, 2021, 08:59:01 pm
content: 28 or 30 AWG kynar wirewrap or magnet wire, a connector to mate with your half pitch one, and a 0.1" square pin header (not 2.5mm, its 2.54mm) to mate with the 'Dupont' ended leads. Tape them both down to the bench and solder the wires between them, then put them on a polypropylene takeaway container lid so the glue doesn't bond to your bench and strain relieve the wires over the solder joints, preferably with Epoxy (clear or white, not metal filled) or at a pinch hotglue (but only if it isn't going to be exposed to heat and doesn't need to last for many years).If you don't have a mating connector for the half pitch one, you are basically FUBARed, though as a short term bodge to connect to a male connector, that *MAY* just be reliable enough for a single session, you could try cutting a block from a foam plastic wine cork to fit in its housing, piercing a hole for each pin with a needle, then inserting stripped wire ends into the holes. Bring the wires up the side of the foam block and tape them to it as the pins must go into the holes the same direction as the wires did.

author: lpc32
author_rank: Frequent Contributor
timestamp: January 25, 2021, 03:28:52 pm
content: That's the problem, I don't have a 1.25/1.27mm connector, nor many other basic bits and bobs.I thought, maybe I'd find a JST-style connector on an old graphics card fan, but what I found is larger.Then, maybe I have somewhere an IDC clamp-on connector (not on a ribbon cable) that I could use without needing a crimper, assuming the wire gauge fits...

author: lpc32
author_rank: Frequent Contributor
timestamp: January 28, 2021, 03:54:04 pm
content: Well, this works in a pinch:

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 30, 2021, 09:40:21 pm
content: You can simply solder the wires and close them with a heat shrink.

author: lpc32
author_rank: Frequent Contributor
timestamp: January 30, 2021, 09:55:21 pm
content: I actually like this form better.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 30, 2021, 10:06:19 pm
content: Yes, a good solution, but I do not like these pins - they always strive to lose contact or completely jump off.
Improvised connector for Li-Ion phone batteries (bent paperclips) - Page 1
Forum section: electronics / projects

author: RoGeorge
author_rank: Super Contributor
timestamp: December 27, 2022, 12:40:09 am
content: Recently had to charge/discharge/measure the capacity of various Li-Ion cells outside of their phones, and didn't have proper connectors for each type of battery.Found out that paperclips have enough springiness, yet are still malleable and easy to bend in arbitrary shapes. Can be shaped in a minute, dirt cheap to make. In practice the paperclip connectors worked better than the other more laborious attempts with pogo pins.
Improvised dry heat temperature disinfection unit - Page 1
Forum section: electronics / projects

author: profdc9
author_rank: Frequent Contributor
timestamp: April 04, 2020, 01:12:26 am
content: Hello.I have a first version of my improvised dry heat temperature disinfection unit. You can find it athttps://drive.google.com/open?id=1NDP7rlqqLaXC3IBCSmcZSbiw1HuZUOUfThe github with the software and PCB is athttp://www.github.com/profdc9/SimpleTempControllerAny comments are welcome. It is intended to be built with basic components that are available at hardware stores by people like yourself of all different skill levels.Dan
IMX219 MIPI CSI Camera FPGA rx implementation, Datasheet Discrepancy  - Page 1
Forum section: electronics / projects

author: RoadRunner
author_rank: Frequent Contributor
timestamp: February 16, 2020, 09:59:52 pm
content: Quote from: RoadRunner on February 16, 2020, 09:43:13 pmI have just published a Project with Lattice FPGA interfacing to IMX219 Raspberry pi camera.As this is a RAW camera sensor , to get color outof the image Debayer / demosaic need to be performed .But the problem is datasheet of the camera is quite ambiguous when it comes to what bayer patter this camera has. IMX219 datasheet incorrectly mention output as to be either GBRG or RGGB. but linux driver code says IMX219 Camera only output BGGR , MEDIA_BUS_FMT_SBGGR10_1X10 .Problem is if i set FPGA's debayer filter input format to BGGR live image comes good in colors. but Test patterns which are defined in camera datasheet have R and B channels exchanged.And when i set FPGA's debayer filter type to RGGB test pattern comes exactly as the camera datasheet but live image have R and B channels exchanged so what ever is actually blue will look red and what ever is red will look blue in live image.Image attached to this post shows the issue.Datasheet can be found here.https://github.com/circuitvalley/mipi_csi_receiver_FPGA/tree/master/Camera%20DatasheetMy question is anyone worked with this kind of camera or may be this exact camera can shine some light on what is wrong.I have published two youtube videos, but i am still new bie to videos.Regards

author: RoadRunner
author_rank: Frequent Contributor
timestamp: February 25, 2020, 07:20:38 pm
content: Just in case if someone is interested i have found solution to the problem with help from Raspberry pi. Solution is Flipping image changes the bayer pattern also but it only affect data from sensor array. As test pattern is auto generated test pattern bayer pattern is fixed.If you some one is interested i have made another video showing quality and frame rate up to 1000FPS at low resolution.As this camera sensor does not have auto exposure or white balance control. I will be possibly implementing some algorithm in FPGA. If Someone has any know how. How to approach problem of auto exposure in FPGA please shine some light.Regards
IN-12A Nixie Tubes poor shipping plus 1 broken tube - Page 1
Forum section: electronics / projects

author: Ferroto
author_rank: Frequent Contributor
timestamp: November 03, 2015, 06:07:54 pm
content: Recently I ordered 6 IN-12A Nixie Tubes from the Ukraine off ebay and was less then impressed with the shipping and when I picked up the package I heard broken glass.My suspicions confirmedA closer look at the damageThe other 5 seemed ok but I still got to make a driver circuit to test them to know for sure.Also a quick question are there harmful compounds other then glass in the broken nixie tube. I was thinking of tearing it down further.

author: marshallh
author_rank: Unknown
timestamp: November 03, 2015, 06:52:24 pm
content: There may be a small amount of mercury (less than a CCFL tube)

author: SeanB
author_rank: Super Contributor
timestamp: November 03, 2015, 06:56:01 pm
content: Glass, and the metal will have a small amount of Thorium in it to aid striking. Do not eat the glass or metal, and wash hands after handling with soap and water are about the best precautions. Handle like a broken incandescent lamp, the small amount of Ne that was in there is long gone, and it is an inert gas in any case.

author: Fungus
author_rank: Super Contributor
timestamp: November 03, 2015, 08:47:13 pm
content: Quote from: marshallh on November 03, 2015, 06:52:24 pmYep. Be sure not to eat the glass.

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: November 03, 2015, 10:35:56 pm
content: Wutt? You are not supposed to eat the broken glass and the thoriated metal parts of a broken tube?but those are my favorites!I actually disassembled many tubes. Just try not to cut your fingers while working, the metal pieces and glass can be realy sharp! And as already said: don't eat the broken glass and the toxic metal!

author: GreyWoolfe
author_rank: Unknown
timestamp: November 04, 2015, 03:48:04 am
content: Quote from: Fungus on November 03, 2015, 08:47:13 pmWell, that just takes all the fun out of it.
In circuit EEPROM programming via serial coms? - Page 1
Forum section: electronics / projects

author: max_torque
author_rank: Super Contributor
timestamp: May 23, 2014, 05:25:30 pm
content: I was wondering what program or application people use to program eeproms when they are not directly accessible, ie via a serial com link (RS232/CAN/USB etc)? Basically, before i go an write my own program to do this, are there any out there that are open source etc??
In circuit testing of MOSFETs - Page 1
Forum section: electronics / projects

author: ocset
author_rank: Super Contributor
timestamp: October 11, 2017, 07:25:57 pm
content: Hello, the following concerns in-circuit-testing of N type mosfets, in circuits that are powered off (and all capacitors discharged)..-do you believe we would agree that in the following current regulator circuit, the MOSFET would be deemed dead if (when powered off)…………1…..Drain to gate was seen as short circuit or low ohms with a DMM on low ohms setting2….Gate to source was seen as short circuit or low ohms with a DMM on low ohms settingAlso, if we first probed the NFET in circuit with a DMM on low ohms setting, and with black probe to gate and red to source……..then……if we next probed from Drain to source on a low ohms setting and saw a short circuit, then the fet would be deadDo you agree with the above?(schem and ltspice attached)

author: Ian.M
author_rank: Super Contributor
timestamp: October 11, 2017, 07:47:04 pm
content: Only if the low-ohms range has a maximum output voltage under 0.5V so no PN junctions conduct significantly. If the test voltage is higher, a drain to gate short or a drain to source short with the drain positive (or low ohms for either) would immediately indicate failure, but you'd need to know the typical resistance to ground of the unpowered LT6220 before concluding anything on the basis of the gate to source resistance.

author: ocset
author_rank: Super Contributor
timestamp: October 12, 2017, 05:12:34 am
content: Thanks, if i test 100 of the products of post #1, and 99 are "open circuit" from D-S and D-G, ..but then one product is found to be having short circuit from D-G and/or short cct from G-S, then surely you can say that that one product has a failed mosfet?(i am speaking of testing with a DMM on low Ohms setting)

author: Ian.M
author_rank: Super Contributor
timestamp: October 12, 2017, 09:45:55 am
content: Sure. Even comparison with ONE known good working board would tell you that. However if the MOSFET was damaged during assembly e.g. by ESD and the gate oxide has been punctured, it may not be leaky enough to read as shorted on a low ohms range until its been powered for the first time and it and the LEDs have destroyed themselves.To pick up such a fault *BEFORE* destroying the LEDs and probably the OPAMP, you need to look for more than just dead shorts. You expect a bit less than 22K (your gate pulldown) between gate and source, and by testing the good boards (even ten would do to start with) and plotting the results, you'll get a feel for the acceptable range of resistance values between your selected test points. Those ranges of values will then be usable for Go/NoGo testing, as long as you use the same model DMM on the same range (or same autoranging mode).
In-Line or Low-Side phase current monitor - Page 1
Forum section: electronics / projects

author: Yaroooo
author_rank: Regular Contributor
timestamp: January 16, 2020, 11:08:36 am
content: In a current monitor application, using a shunt resistor per phase plus amplifier and ADC, it's easier to implement an in-line or a low-side shunt resistor?Especially with drive frequency of 30Khz and low duty cycle with voltage coil up to 48V, in-line monitor is less susceptible to PWM interference?

author: capt bullshot
author_rank: Super Contributor
timestamp: January 16, 2020, 11:24:47 am
content: Quote from: Yaroooo on January 16, 2020, 11:08:36 amAre you talking about a dual or triple H-Bridge used for Motor Control or AC output (like Class D amplifier)?The answer is as usual: Well, it depends.Low side shuts have one end of the shunt tied to GND, a (at least at the first glance) rather stable potential, so you won't have to deal with large common mode voltages. Stray impedances can completely spoil that.If you're using per phase current sensing, you can take advantage e.g. for short circuit and ground fail protection purposes, but you have to deal with large common mode voltages anyway, so some kind of high CMRR at high frequencies is mandatory here, no matter if you realize that by specially designed sense amplifiers or by some signal isolation means.If done correctly, low side sensing usually is preferfed for lower power / lower voltage (what is a quite flexible definition) for cost reasons.
In-production, stereo, non-BGA, 3.3V codec with headphone amp? - Page 1
Forum section: electronics / projects

author: andrejr
author_rank: Contributor
timestamp: May 07, 2024, 02:01:38 pm
content: Hi everyone, does anyone know of a modern, in-production replacement for WM8978 and UDA1380?I'm looking for a 3.3V-powered I2S stereo codec (ADC/DAC) that has the capless headphone amp feature, and that's not BGA (regular SMD preferred).WM8962B is the only in-production chip I know of, but I'd rather avoid BGA if I can (this one is my last resort).Searching more deeply, I found these TI candidates:TLV320AIC3104TAC5142TLV320AIC3105But none of them are widely used for open-source projects. Sure, getting a codec to work through I2S isn't rocket science, but it'd be nice to have a chip that has examples I can easily use.Got any suggestions?
In search for IP67 2.5mm panel mount DC Jack/Barrel  - Page 1
Forum section: electronics / projects

author: hcglitte
author_rank: Regular Contributor
timestamp: February 06, 2018, 11:07:34 am
content: Hi,Does anyone know of a manufacturer that produces standard DC Jacks which is waterproof?The connector should have an o-ring or gasket and should be watertight without a cover/cap being necessary.The latter is important since the end customer may forget to use the cover/cap.I have tried searching on Alibaba but I have not found any.Thanks.

author: xani
author_rank: Frequent Contributor
timestamp: February 06, 2018, 12:54:34 pm
content: maybe try typing "waterproof DC jack" in google. There seem to be plenty of choices

author: hcglitte
author_rank: Regular Contributor
timestamp: February 06, 2018, 04:51:20 pm
content: I have tried of course...(!)This does not produce any relevant results, unfortunately. As the subject states: Panel mount.The search results are semi waterproof types with caps.There is one result from GT which is excellent. This is 3.8 USD @ 100 pcs. Quite expensive...

author: IDEngineer
author_rank: Super Contributor
timestamp: February 06, 2018, 08:55:32 pm
content: Quote from: hcglitte on February 06, 2018, 04:51:20 pmDoesn't sound that expensive to me for a waterproof connector. In most of my designs, when waterproof connectors are required, they are the single most expensive component in the whole system.

author: Gribo
author_rank: Frequent Contributor
timestamp: February 06, 2018, 10:12:00 pm
content: There is also Switchcraft, slightly more expansive than GT, but easier to source.

author: hcglitte
author_rank: Regular Contributor
timestamp: February 06, 2018, 10:54:31 pm
content: I have tried the DC connectors from switchcraft. They are really bad in my opinion.They do not handle normal "short" length barrel connectors (normal Power Supplies).They are actually designed to be used with their own plugs which are really long (which they told me).Also, they are not waterproof unless you use the cap they supply.I have 50 pcs lying in the shelf somewhere...I agree that they typically are expensive, and that 3.8 USD may be a good price. However, I was hoping that there could be a less costly part available.As a comparison, I am able to get hold of a IP67 RP-SMA with U.FL pigtail for 2.3 USD - and I have even seen these on aliexpress for 0.7 USD.Samtec has them for about 6 Euro!
In search of Market Analysis - Page 1
Forum section: electronics / projects

author: Inquiring Mime
author_rank: Newbie
timestamp: October 24, 2024, 04:28:37 pm
content: This may not be the right place, but I'm looking for access to current/recent market reports for Cadmium and for Cadmium-Sulfide (CdS) photoresistors for a Business Plan I'm trying to write. Those things are in excess of $2500 each, and I have zero capital.I'm not asking the whole report, but projected CAGRs and maybe historical charts/graphs would be SUPER helpful.Thank you all!

author: Inquiring Mime
author_rank: Newbie
timestamp: October 24, 2024, 04:37:25 pm
content: A link to an example source:https://industrygrowthinsights.com/report/light-dependent-resistors-market/

author: RJSV
author_rank: Super Contributor
timestamp: October 24, 2024, 04:49:32 pm
content: You had me going, for a second, until I figured out that you were referring to the price of the report.I have a few CDs sensors that were maybe $3 each, but that's at the former Radio Shack.A lot of these info sources are a challenge, as I suppose our 'image' is of a guy holding a soldering iron, while squinting at a DMM.Today, that Engineer is often a woman, creating documents and plans, and later jumping into a truck, to go down to a facility to inspect some 18 kva equipment.

author: Inquiring Mime
author_rank: Newbie
timestamp: October 24, 2024, 05:17:22 pm
content: "A lot of these info sources are a challenge, as I suppose our 'image' is of a guy holding a soldering iron, while squinting at a DMM.Today, that Engineer is often a woman, creating documents and plans, and later jumping into a truck, to go down to a facility to inspect some 18 kVa equipment."A perfectly valid, yet irrelevant, observation.

author: Inquiring Mime
author_rank: Newbie
timestamp: October 24, 2024, 05:39:09 pm
content: Sorry RSJV - that came off harsh. Which I did not intend.
In search of resources to learn about MMUs - Page 1
Forum section: electronics / projects

author: JustClaire
author_rank: Contributor
timestamp: February 25, 2020, 09:22:03 pm
content: Hello, forumOn my journey into learning digital electronics, i decided to learn about MMUs(and possibly design a simple one, as simple as they can be, just for fun).I am currently looking for any information about MMUs - programming guides, datasheets, tutorials, forum posts, etc. So if you know anything that can help me, please link these resources, i will very much appreciate it

author: rstofer
author_rank: Super Contributor
timestamp: February 25, 2020, 11:11:48 pm
content: Maybe this will help:http://www.tldp.org/LDP/tlk/mm/memory.htmlThe thing about virtual memory is that it is both hardware and software.Try to find PDP11/70 manuals in BitSavers - they might help. Maybe even IBM 360,370 or Amdahl 470 manuals (I didn't look).This topic is covered well in books related to computer hardware design. I don't have any to recommend at the moment.

author: rhodges
author_rank: Frequent Contributor
timestamp: February 26, 2020, 08:41:43 pm
content: If you can easily find a book on MIPS (eg, "See MIPS Run"), that might be of interest. When I was doing embedded MIPS, I had to be somewhat familiar with the page fault handler and the mapping descriptors.

author: nctnico
author_rank: Super Contributor
timestamp: February 26, 2020, 08:53:15 pm
content: A book about the 80386 processor is also helpful. It is interesting to see so much 'old' technology being suggested; I like it because the underlying principles never changed but more complication got added.
in what cases do you decouple a capacitor between the voltage rails? - Page 1
Forum section: electronics / projects

author: CopperCone
author_rank: Super Contributor
timestamp: August 28, 2017, 07:59:01 am
content: I have seen some circuits that use bipolar supplies for amplifiers to put a decoupling capacitor not only to gnd but also between V+ and V-.It seems to be included in some circuits, including professional datasheets from LT.What condition would you recommend this choice for (i.e. what issues can it solve).

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 28, 2017, 09:17:52 am
content: Well, what's the capacitor doing, anyway?It's putting impedance between two nodes. In a bypass application, it's furthermore being used as a ~zero impedance at AC.Anywhere that's useful, is a good place to put a capacitor.Whether that's necessarily useful in a bipolar supply circuit, depends on the circuit.Op-amp circuits, for instance, have different PSRR for VCC and VEE. It might be that the magnitude and sign is appropriate for placing a capacitor between rails, rather than from each rail to ground (though it seems unlikely that this would be the case).And what does PSRR mean, with respect to a single supply, anyway? One factor is gain to the input: the input stage is typically a diff pair, so one supply will couple more strongly, say by mismatched collector capacitance inside, versus the low impedance emitter side (taking a BJT diff amp as an example op-amp input stage). Another is gain to the output: independent of what the input (diff amp) is doing, the gain or output stage may have capacitance to one rail (usually the gain stage, because that's where its Miller capacitance, and the dominant pole compensation, is referenced to). R2R outputs can have high gain to both rails.I talk about PSRR because it should be indicative of stability problems, as well as susceptibility to power supply noise.Conversely, if the capacitor is there to combat a noise source, is it differential or common mode? Example: a full wave doubler can be used as a bipolar source, but it has common mode ripple: one rail is being charged, while the other is being discharged. Both supplies rise and fall at the same time. When used as a unipolar source, the two half-wave ripples cancel, and you get full wave ripple, hence the name. A capacitor across +/- can't help with that.However, if it is differential mode noise (like a flyback SMPS using a centertapped secondary winding, so both rails get a pulse of charge at the same time), then a capacitor between them works just as well as a split capacitor to ground. (That is, for VCC -- capacitor -- VEE, use VCC -- 2*capacitor -- GND -- 2*capacitor -- VEE; since no net current flows to GND, the 2*capacitors act in series, equivalent to 1*capacitor from VCC to VEE.Mind that capacitors cannot be used carelessly: they are not ideal zero-ohm AC impedances. Even if they were, you still wouldn't want that, either... One must see the power distribution network (PDN) for what it is: an RLC equivalent circuit, with resistance, reactance, and frequency dependence. It is an optimization problem, not a minimization problem.Tim
INA118 common mode voltage range and design issue of current monitor with 3v sup - Page 1
Forum section: electronics / projects

author: basantab
author_rank: Contributor
timestamp: January 06, 2019, 05:06:44 pm
content: Hellothe circuit below is for monitoring current level.It works if i supply INA118 with more than 3 volt(in my case i supplied 9 volt and also works with lower than that as well).My curiosity is with Common Mode Voltage Range. Can someone validate whether or not i am saying or doing right ?So using circuit below i have sense resistor which dissipate around 0.1 mv and ina118 is amplifying and comparing it with comparator.The voltage input on negative leg is 4.5 volt and positive leg is around 4.6 volt. (if i am right) according to INA118 datasheet CMVR if(vcc-1 to gnd+1.1) which gives me the space of high 2 volt to low 1.1 volt (with vcc of 3 volt) common mode voltage input and cmvr is average of two inputs meaning i can input average signal of 1.1 volt to 2 volt (?). But in my case both leg gets at least 4.5 volt meaning it exceeds the CMVR and output is not linear (am i right). So can there be in-amp which can take input(average) of higher than vcc or supply volt..the problem is it goes into the circuit which has 3 volt supply (lets say no-boost conv for now)... and also the constant current generator is lm334 which requires at least more than 3 volt to produce cc into load of 15k ohm or more. Is there any ICs that takes 3 volt or less and can produce CC of 300ua into 15k or more load (i know mathematically it sounds awkward but if there is any magical way then it would be nice :-)Can anyone validate that i am doing it right ? (personally i want to try current shunt monitors if this doesnot work).thankyou so much for reading all this..

author: basantab
author_rank: Contributor
timestamp: January 06, 2019, 06:15:36 pm
content: And also i have tried inputting voltage more than common mode voltage or average voltage on both more than (vcc-1volt in case of ina118) and the output is nonlinear.
INA121 Inst Amp - output offset vs Frequency - strangeness! - Page 1
Forum section: electronics / projects

author: max_torque
author_rank: Super Contributor
timestamp: June 19, 2017, 11:27:08 am
content: I have an INA 121 in a device. It's powered +-15v, has a differential input signal, and spits out a single ended copy, with the amps gain at 1 (INA121 uses single resistor for gain setting, and no resistor = gain 1). So far so good.http://www.ti.com/lit/ds/symlink/ina121.pdfThe datasheet (page 4) shows gain of 1 flat to around 200 KHz.What is interesting what happens above that point. As expected the output amplitude falls as frequency increases, no surprises there, but the output offset actually moves! If i feed in a +-1Vpkp signal, centered around 0v, then as the input frequency climbs above around 300KHz, the output of the amp, which is by now around 0.6V pkp, climbs and is now centered around approx 0.5V above the ground reference?Ok, fair enough, this is possibly outside the claimed operating zone of the amplifier, but what are the causes of this (unbalanced gain on the input amplifiers?) and is there anything in the datasheet i've missed that tells me this can occur??I'll grab some screen captures from the scope in a second to show this!

author: tszaboo
author_rank: Super Contributor
timestamp: June 19, 2017, 11:55:30 am
content: Its the combination of the 3 graph that are around that. Also, an ina technically does not have 0V power supply, just the ref pin. That leads to some irregularities if ref is not 0V. And huge errors, if ref is driven by something other than a 0 resistance voltage source.Make a filter like on figure 5.

author: max_torque
author_rank: Super Contributor
timestamp: June 19, 2017, 02:20:52 pm
content: Circuit already includes the requisite input filter as per Fig.5 in the 'real' application, which includes a ~100Khz LP filter to prevent the input frequency climbing too high. I'd removed that filter in order to establish the bandwidth / performance of the circuit when i noticed this slightly un-usual behavior....

author: The Chump
author_rank: Contributor
timestamp: June 20, 2017, 07:21:18 pm
content: You are hitting the (probably asymmetrical) slew rate limit which is 0.7V/usA 300kHz +/-1Vpk signal has a maximum slew rate of about 1.9V/us
INA240 pin to  pin alternative anywhere? - Page 1
Forum section: electronics / projects

author: LM21
author_rank: Regular Contributor
timestamp: July 05, 2022, 09:52:08 am
content: I have a project with INA240 current measuring ICs. But now their stock is zero, or price much too high. Prices have gone from 4$ to 150$. Has anybody found a pin to pin alternative for them. I am using TSSOP8 package and our common mode voltage is 24V - 50V.
INA241 bi directional current sense ? wiring question  - Page 1
Forum section: electronics / projects

author: Overspeed
author_rank: Frequent Contributor
timestamp: August 15, 2024, 11:28:00 am
content: HelloThe INA2411 allow bidirectional current sense but the TI doc is not very accurate on the bidirectional mode regarding the Ref 1 and 2 connection and th e possible use of an external reference as the REF5025Can some have an explanation on how to wire it as bidirectional as INA241 is cheap but I want to avoid '' dummy stupid test ''RegardsOS

author: tszaboo
author_rank: Super Contributor
timestamp: August 15, 2024, 11:38:52 am
content: Which part isn't clear?If you connect both Ref pins to ground, your output is referenced to GND, and the output voltage is always positive.If you connect one Ref to GND, other to 2.5V, then your output is referenced to 1.25V, so 1.5V is positive, 1V for example is negative current.

author: Overspeed
author_rank: Frequent Contributor
timestamp: August 15, 2024, 12:40:35 pm
content: Quote from: tszaboo on August 15, 2024, 11:38:52 amHlloThanksThey write in 8.4.3The INA241x can operate in either a unidirectional or bidirectional mode based on the voltage potential placed on the reference pins.The linear range of the output stage is limited to how close the output voltage can approach ground as well thesupply voltage as described in the Specifications.in the link specification :Supply voltage(VS)22 VAnalog inputs,VIN+, VIN- (2)Differential (VIN+) − (VIN-) −30 30 VCommon-mode −20 120 VREF1, REF2,NC inputs GND − 0.3 VS + 0.3 VSo my question asked from another way :Does this IC work for biderectional current as 48 V load / 48 charger ? or even 36 Volt as they specify INA241x –5 V to 110 V, Bidirectional ?OrDoes i ned another IC / circuitI am not an expert in current sense IC bidirectionalRegardsOS

author: tszaboo
author_rank: Super Contributor
timestamp: August 15, 2024, 12:55:57 pm
content: For 48V, you connect the two inputs to a shunt in series with your 48V supply.Power it from another voltage like 5V.Connect the REF pins as discussed already.Inputs will be above the power supply.Test it of course before deciding. I've had shunt monitors that were supposed to work low side, but they had terrible offset voltage if not used on the high side.

author: tszaboo
author_rank: Super Contributor
timestamp: August 15, 2024, 12:57:04 pm
content: Oh, and I just checked for you, TINA-TI has the model of this IC. You can simulate your circuit.

author: Overspeed
author_rank: Frequent Contributor
timestamp: August 15, 2024, 01:02:59 pm
content: Quote from: tszaboo on August 15, 2024, 12:57:04 pmHelloOk I will try simulation that better to smoke real componentsRegardsOS

author: Overspeed
author_rank: Frequent Contributor
timestamp: August 15, 2024, 06:29:27 pm
content: HelloAnalog doc AD8418 provide a more easiest explanation I link the screen print on '' how that works '' than the TI docRegardsOS