hybridfree/eevblog-posts huggingface dataset:
LCR meter - Page 1
Forum section: electronics / projects

author: z3bb0
author_rank: Newbie
timestamp: June 29, 2015, 08:51:24 pm
content: So I'm trying to build something a little more advanced than what I've built before and I've decided that I want to build an LCR meter. In terms of performance I'm thinking measuring capacitance down to 1pF, inductance down to 1nH and dc resistance as well as ESR down to 1mOhm and by down to I mean that 1mOhm is the least signifigant digit, measuring frequency 10Hz - 100KHz. So what I think I will do is have a dac output the signal though the DUT, and measure the current and voltage across the DUT. Nearly exacly how the HP4263A works, see video at 11:23, but with out the vector ratio detector. What I want help with is what kind of sample rate and resolution is required for both the DAC and ADC.I've stumbled across this part and figure it might be enough, but since I really have no idea what I'm doing... This is the chip I'm figuring might work as the ADC: AD9201 10bit, 20Msa/s, 2 channels one for current and one for voltage allowing me to measure the phase and thus get ESR and reactance in one measurement. Is 10 bit really enough though? or should I do something like having a 1 channel ADC and measuring the impedance at 2 different frequencies say 95 and 105 Khz and then solving for the ESR. And lastly if I where to use the AD9201 or what ever you suggest, what kind of microcontroller is needed to use the ADC control the DAC and control some kind of low res display or possible four 14segment displays or something similar, to clearify: what kind of power is needed I don't want to use some expensive ARM chip where the programming tool costs 500$. Thanks for the help in advance!Video:
LCR SMD Fixture Modification - Page 1
Forum section: electronics / projects

author: mawyatt
author_rank: Super Contributor
timestamp: June 08, 2022, 07:35:37 pm
content: We've been using a couple SMD fixture adapters with our LCR meters to measure various SMD devices, and developed a DC Bias adapter to work with thes (and other LCR meter fixtures).https://www.eevblog.com/forum/projects/bias-network-for-lcr-meter/msg4170607/#msg4170607The two SMD fixtures are different and one has a much steeper "V" groove and the probe tips are slightly higher in the V groove bottom which makes attaching small SMD devices much more difficult than the other fixture which has a shallow "V" groove and less space between the groove bottom and the probe tips. Because of this the one SMD fixture didn't get used often, and we decided to see if we could 3D print a "V" groove guide to replace the stock guide.The 3D printed guide uses a shallower "V", which has the groove higher and closer to the probes, and is wider (10mm vs 8mm) to support longer SMD devices. This 3D printed quide works much better than the supplied stock guide, especially with small & thin 0603 devices, yet handles the larger SMD devices fine.The 4th image 3180 is the other fixture which has a standard shallow "V" groove which was our "GoTo" SMD fixture before, but the 3D printed guide fixture is even easier to use!!Note: The zip file is the guide .stl file, rename with .stlBest,

author: jwet
author_rank: Frequent Contributor
timestamp: June 27, 2022, 05:40:38 pm
content: This is very good- I build little temporary fixtures for various tasks around my electronics and machine shop with my 3d printer. A few of the things - 18650 battery holders for testing and charging raw cells, replacement plastic knobs and levers on test fixtures- old HP plastic gets brittle. There is a photo below of a different type of SMT fixture that I fixed this way. The colors and design are different because I did them at different times. Good work.
LCR tester with DC bias. - Page 1
Forum section: electronics / projects

author: schmitt trigger
author_rank: Super Contributor
timestamp: July 21, 2024, 09:28:30 pm
content: 've been wanting to investigate the actual capacitance of class-II MLCC, operating with the actual workingbias. And yes I know that MLCC manufacturers publish typical data.Conceptually, the idea is simple: connect a LCR meter to the cap under test while adding in parallel a variable DC power supply.But even a dimwit like myself knows that this would be a VERY STUPID IDEA. At best, the supply will add a parallel impedance which will load the reading. At worst, the LCR will let out the magic smoke.What I have struggled to figure out, is how would one isolate the LCR from the supply and viceversa. I am aware that some higher end LCR meters incorporate a DC bias option.Any ideas how that could be done?Edit: I also have posted this same question in another forum.

author: magic
author_rank: Super Contributor
timestamp: July 21, 2024, 09:42:24 pm
content: For measuring junction capacitances of semiconductors I came up with this: isolate the meter from DC bias using a second capacitor with much lower impedance (higher value) in series, isolate the bias source using a resistor with much higher impedance (resistance).Maybe this could work for MLCCs too, using an electrolytic to AC couple the cap under test.

author: gamalot
author_rank: Super Contributor
timestamp: July 21, 2024, 10:30:37 pm
content: Some LCRs come with a built-in bias voltage source and some don't. When your LCR doesn't have it built-in, or its voltage range is too low for your application, you can consider an external voltage source.You can consider buying an external voltage source adapter, or DIY a similar device to meet your needs.Reading the Keysight Impedance Measurement Handbook will help.https://www.keysight.com/au/en/assets/7018-06840/application-notes/5950-3000.pdf

author: mawyatt
author_rank: Super Contributor
timestamp: July 21, 2024, 11:06:24 pm
content: If one is able to DIY, here's some threads one might find usefulhttps://www.eevblog.com/forum/projects/bias-network-for-lcr-meter/https://www.eevblog.com/forum/projects/ceramic-capacitor-behavior/https://www.eevblog.com/forum/testgear/lcr-meter-plot-software/https://www.eevblog.com/forum/projects/lcr-lab-grade-parameter-plotting-fixture/We've measured everything (with this DC Bias Fixture and Techniques) from various ceramic types, to Electrolytics, to Tantalums, to Polymers, to Mylar, Polypropylene, Polystyrene, to Mica, to Diodes, to Zeners and so on. We can report this adapter and technique works quite well indeedBTW we are considering creating a Special Version to venture above the typical 100KHz limitations of most LCR Meters, as well as into extremely high Capacitance (>1mF) devices, if interested let us knowBest,

author: schmitt trigger
author_rank: Super Contributor
timestamp: July 22, 2024, 05:12:54 pm
content: I understand now, the protection diodes are the piece of the puzzle that was missing in my brain.Thanks!
LCX058AKC + LC98500 - mini 1.4 inch LCD from SONY reverse engineer - Page 1
Forum section: electronics / projects

author: Vector101
author_rank: Newbie
timestamp: February 16, 2018, 09:24:04 pm
content: The purpose of this project is to reutilize the LCX058AKC type of mini LCDs that usually are used in digital cameras.As the project will progress I will update this page with the information I find.If anybody would like to lend a hand that would be helpful.The final target is to use a STM32 or ESP to drive the LCD if possible or find an alternative for the custom LC98500.LCX058AKC - no datasheet - 1.4 inch LCDLC98500 aka TPG018A - no datasheet SANYO/PANASONIC Custom ASIC - LCD driver usually drives 2 LCDS main camera pannel or EVF

author: PhillyGreg
author_rank: Contributor
timestamp: February 17, 2018, 02:28:00 am
content: Perhaps, this might be a place to start?https://www.eevblog.com/forum/projects/drivin'-a-sony-lcd-viewfinder/Looks like the same part, and the OP attached a datasheet.No progress made, but the datasheet seems to be complete enough to get it running.
LDK130 not 3V3 but 3v9!! [SOLVED] - Page 1
Forum section: electronics / projects

author: Ribster
author_rank: Frequent Contributor
timestamp: October 21, 2015, 07:30:32 pm
content: I've got a voltage regulator, when turned on gives me 3v90.I'm sure it is the 3v3 version, as per datasheet has the 33 marking on it. It's the DFN-6 version.http://www.st.com/web/en/resource/technical/document/datasheet/DM00076097.pdfAnyone knows what is going on ?

author: marshallh
author_rank: Unknown
timestamp: October 21, 2015, 07:34:46 pm
content: Put a load on it (such as 10k resistor)

author: Ribster
author_rank: Frequent Contributor
timestamp: October 21, 2015, 07:38:00 pm
content: Yup, did that! It goes down with the load.I thought 33R eventually shorted it..I'm suspecting my pinout to be the culprit.I've took a new part, soldered that one down, same thing..

author: Ribster
author_rank: Frequent Contributor
timestamp: October 21, 2015, 07:41:24 pm
content: Shit! I don't have pin 2 connected to gnd!

author: Ribster
author_rank: Frequent Contributor
timestamp: October 21, 2015, 07:43:37 pm
content: Quote from: AcHmed99 on October 21, 2015, 07:39:55 pmOh, i think i have 40uF on the output. Also a capacitor inverter.I should lower the output capacitance then! Thanks a lot!

author: Ribster
author_rank: Frequent Contributor
timestamp: October 21, 2015, 07:56:32 pm
content: Okay, bodged pin 2 to ground. (My hardest fix until date :p)And i got 3.37V out. Also have a noise of 30mVpp.Thanks for the input guys!
LDMOS enquiry - Page 1
Forum section: electronics / projects

author: nagz
author_rank: Contributor
timestamp: July 02, 2025, 10:51:27 pm
content: Hi,I'm building an amp for HF frequencies and am looking at LDMOS's, specifically the NXP MRF1K50H.I've found online that NXP was once known as Freescale, which forms the basis of this enquiry.I've seen both NXP and Freescale versions of this device online and there is quite a difference in price between the two, with NXP being more $$$$$.Query is, in your opinions, do you think the Freescale versions found online are inferior to the NXP?I'm hoping they are ok so i can save some $$ and get a few Freescales.Cheers

author: Benta
author_rank: Super Contributor
timestamp: July 02, 2025, 11:05:37 pm
content: Quote from: nagz on July 02, 2025, 10:51:27 pmThey're the same. Freescale and NXP merged 10 years ago, and the NXP parts are produced in the former Freescale fab.But logically, the Freescale parts are at least 10 years old, which is an issue for professional manufacturing. If this is a hobby project, it doesn't matter.

author: nagz
author_rank: Contributor
timestamp: July 02, 2025, 11:16:08 pm
content: Hi Benta,It is a hobby project, amplifier for HAM radio.It would be a massive saving to use the Freescale versions, thats for sure, and there seem to be plenty on ebay

author: langwadt
author_rank: Super Contributor
timestamp: July 02, 2025, 11:30:15 pm
content: Quote from: Benta on July 02, 2025, 11:05:37 pmand ~20 years ago Freescale was Motorola

author: Geoff-AU
author_rank: Frequent Contributor
timestamp: July 03, 2025, 12:01:41 am
content: Quote from: nagz on July 02, 2025, 11:16:08 pmEbay? 99% chance they're counterfeit, and will be a source of great disappointment for you sooner or later.

author: nagz
author_rank: Contributor
timestamp: July 03, 2025, 12:35:20 am
content: yeahi really need to source an alternate point of sale and get genuine at a cheaper price, but i think i'm going to have to bite the bullet
LDO design and simulation  - Page 1
Forum section: electronics / projects

author: JYuan
author_rank: Newbie
timestamp: November 30, 2017, 04:18:41 pm
content: Hello,I trying to using Candence to simulate a LDO design.In my design, may I know why ony one tansistor(Transistor M6) isnt work in saturation mode.Is there any wrong with the value of source ,resistance ,capacitance or wire connection ?and the output (Vout=460mV)is too small, how to improve it?Thank

author: Kleinstein
author_rank: Super Contributor
timestamp: November 30, 2017, 04:46:45 pm
content: The LDO is currently set to output about 12 V. My suggestion would be swapping R1 and R2 values to bring it to a more realistic 1.3 V range.

author: JYuan
author_rank: Newbie
timestamp: November 30, 2017, 05:42:24 pm
content: Thank for relying me.May I know how to get 12V at output voltage?Sorry, becuase I am beginner for designing a LDO.Can you give me more suggestion? I really need some suggestions to improve the design.

author: Kleinstein
author_rank: Super Contributor
timestamp: November 30, 2017, 06:27:58 pm
content: M3 and M6 are used as a differential amplifier. This is usually done for near zero difference. R1 and R2 are a divider (1/11) for the DC feedback, this the regulator is made for about 11 times the 1.2 V ref. voltage at the input of M3 - thus 13.2 V.

author: Damianos
author_rank: Frequent Contributor
timestamp: November 30, 2017, 08:58:44 pm
content: In a linear regulator you cannot have higher output voltage than the input. So, increase the input voltage.For the 12V, as Kleinstein already mentioned, adjust the R1/R2 ratio.

author: JYuan
author_rank: Newbie
timestamp: December 01, 2017, 03:26:55 am
content: Thank your suggestion.I already swapp R1 and R2 values and change input of M3 equal to 13.2V.But the simulated result, voltage value increase a bit and still in milliunit.I wondering, is it the Vref is the input voltage in this design?May I know how the effect of ratio(R1/R2) wil affect the transient response and DC response?I has uploaded the results, please help me take a look.

author: JYuan
author_rank: Newbie
timestamp: December 01, 2017, 03:33:23 am
content: Thank for answering my question.I has change the value of Vref to 13.2V.But, the Transistor M3 will not operation in saturation mode.and M6 still will not operation in saturation mode.
LDO dropout question - Page 1
Forum section: electronics / projects

author: bhj99
author_rank: Contributor
timestamp: September 18, 2024, 02:26:38 am
content: Hello, I would like to use the MIC61300 LDO to generate 2.5V and 3.0V power rails from a 3.3V power supply. I expect current draw of 100 mA on the 2.5 V rail and about 250mA on the 3.0 V rail. Would the MIC61300 be an appropriate choice for my requirements or should I pick another LDO? Would the 3.0V rail be problem if considering the 350mV max dropout voltage spec and it would enter dropout region? Any help is appreciated.

author: Kim Christensen
author_rank: Super Contributor
timestamp: September 18, 2024, 02:41:25 am
content: Looks like it'll be OK at 250mA:

author: squadchannel
author_rank: Frequent Contributor
timestamp: September 18, 2024, 03:37:00 am
content: 3V rail, I would drop it at Schottky forward voltage.
LDO feedback Resistors parallel res and cap purpose - Page 1
Forum section: electronics / projects

author: electronx
author_rank: Regular Contributor
timestamp: January 21, 2025, 02:28:17 pm
content: What is the purpose of the series res and capacitor connected to the feedback resistors here?

author: magic
author_rank: Super Contributor
timestamp: January 21, 2025, 04:29:48 pm
content: Not sure, but it could be included to improve transient response or very high frequency noise, or maybe it was necessary for stability (counteracting input capacitance of the FB pin or simply adding phase lead in the feedback loop near some critical frequency).It's similar to adding the ADJ capacitor to ground in LM317 applications, but in this case it is only effective at hundreds of kHz and up.

author: AnalogTodd
author_rank: Regular Contributor
timestamp: January 21, 2025, 06:02:05 pm
content: Magic has the right ideas on the use of it. Usually having a capacitor there is frequency compensation for when the loop gain is dropped by having a resistor divider to the FB pin. My guess would be that the part showed some stability issues (not surprising considering they used a 22uF ceramic in 0805 case) and that adding the phase lead helped stabilize things.
LDO in SOT223 with pin out: GND, Vin, Vout - Page 1
Forum section: electronics / projects

author: tom66
author_rank: Super Contributor
timestamp: September 17, 2014, 11:12:23 pm
content: I made a boo-boo and put the pin-out for a SOT89 regulator in place of a SOT223. (MCP1703) Yes, two similar packages have the GND and Vin exchanged, odd.I could fit the SOT89, but it would be running my thermal limits close... Anyone know of a 3.3V LDO, capable of at least 150mA, in SOT223, that has the pin out: GND, Vin, Vout? Must tolerate Vin of 5V.I've checked all of Microchip's portfolio. It's an oddball, that's the only reg they make with that odd pin out, and only in SOT89. Part of me suspects this is for compatibility with another part, but I haven't found any such matches.Thanks

author: Smokey
author_rank: Super Contributor
timestamp: September 18, 2014, 03:34:05 am
content: I don't know of any part that will solve your problem directly... but...Put it on upside down and bend the pins around. Any pin that doesn't reach it's target pad gets a little wire connection. If it needs more heatsinking, solder a little metal tab to the bottom (which is now pointing up).I got about 10 SOT23 dual diodes on a board backwards once. After I soldered them all on upside down with the legs bent, it was really hard to even tell something was wrong. They lined up perfectly upside down

author: 0xfede
author_rank: Regular Contributor
timestamp: September 18, 2014, 09:12:15 pm
content: Probably you'll like these from digikey:AS1360-33-TCT-NDBye
LDO question - Page 1
Forum section: electronics / projects

author: hithesh123
author_rank: Contributor
timestamp: March 06, 2011, 07:53:54 am
content: I just saw EEVlog on Linear vs. switching.I don't understand why the drop out voltage is less when using a PNP pass element vs NPN.NPN drop is Vce sat + diode drop, but PNP drop is just Vce sat? Can someone explain please.

author: Jimmy
author_rank: Regular Contributor
timestamp: March 06, 2011, 08:47:54 am
content: the n-type has a surplus of electrons, the p-type has holes where electrons should be
LDO regulators. - Page 1
Forum section: electronics / projects

author: nigelwright7557
author_rank: Frequent Contributor
timestamp: August 09, 2018, 02:58:27 am
content: I recently built up a circuit with a PIC32MX220 and a few other analogue components.The first pcb worked fine.So I built up a second one and it didn't work.The problem turned out to be lots of noise on the 3v3 line.I looked up the 3v3 ldo regulator spec and I had a 100nf instead of a 2u2 capacitor on the output.So I swapped it for 10uf.So I built up a third one wit h10uf in it and that was noisy too !It needed a 47uf to get rid of the noise.These ldo regulators are great with low drop out voltages but can be a bit unstable even if care is taken with pcb layout.

author: ANTALIFE
author_rank: Frequent Contributor
timestamp: August 09, 2018, 04:48:35 am
content: So what LDO did you end up using, also post your schematic/pcb too ;^)

author: mzzj
author_rank: Super Contributor
timestamp: August 09, 2018, 06:45:28 am
content: "ESR, Stability, and the LDO Regulator"http://www.ti.com/lit/an/slva115/slva115.pdfhttp://www.ti.com/lit/an/snva167a/snva167a.pdf

author: CJay
author_rank: Super Contributor
timestamp: August 09, 2018, 11:03:55 am
content: Yeah, I found that out too after making the (stupid, I know better) assumption that pin compatible 3 terminal regulators are an easy swap out, it's definitely a good idea to read the datasheets and not assume anything with them so there's a few tubes and a box full of LDO regulators in my W/shop with very clear labels advising me how to use them.Layout wasn't so critical for me (either that or I did it right without trying) but the bypass and filter caps, most important or the 'regulated' rail was awful.

author: james_s
author_rank: Super Contributor
timestamp: August 16, 2018, 07:08:30 am
content: I ran into a similar problem recently. I was repairing a keyboard for an old serial terminal, didn't take long to figure out that the 7805 was dead. I didn't have any 7805's in my stash but I had some other 5V 3 terminal regulator salvaged from something or other so I installed. that. Keyboard powered up but didn't work properly so I spent hours troubleshooting and testing ICs before I had the sense to scope the 5V line and sure enough, crazy oscillation.
LDO voltage regulator with 'auto bypass'? - Page 1
Forum section: electronics / projects

author: sebmadgwick
author_rank: Regular Contributor
timestamp: March 23, 2015, 06:33:26 pm
content: Just an idea... An LDO voltage regulator that automatically bypasses itself when the input voltage is insufficient to regulate the target voltage. This could extend the battery life in certain situations.For example, an MCU may require a supply of 3.0 V to 3.6 V and could be powered from a lithium cell (2.7 V to 4.2V) via a 3.3 V LDO regulator. Normally, the drop-out voltage (e.g. 100 mV) would mean that the MCU would fail once the battery voltage falls to 3.1 V. However, if the regulator was bypassed (input shorted to output) then the MCU would remain operational until the battery voltage fell below 3.0 V.Is this a feature that is already offered by some manufacturers? If not, why not? Too little demand or is the idea flawed?P.S. Please don't suggest that I use a switching regulator. I'm not building anything! Just thinking out loud

author: JohnnyBerg
author_rank: Frequent Contributor
timestamp: March 23, 2015, 06:39:38 pm
content: IMHO most regulators do something like that.For example: I use a 3.3V XC6206 on a 4.2 LiPo battery. When the Lipo voltage drops below 3.4 V, the regulator will follow input with the normal drop of 100mV. So 2.8V Lipo will give 2.7V out.Is it worth the effort to get rid of that last 100mV drop?If its wise to go to 2.8V on a single cell Lipo is a different story

author: sebmadgwick
author_rank: Regular Contributor
timestamp: March 24, 2015, 12:10:51 am
content: Quote from: JohnnyBerg on March 23, 2015, 06:39:38 pmThe circuit could be fairly simple and I'm sure there are some applications that would benefit from getting a little bit more out of a battery.A slightly different motivation could be that LDO regulators will typically offer either low ground current or low voltage-drop (not both together). A bypass circuit could be a useful way of using a low ground current part without having to put up with the higher voltage-drop.

author: dom0
author_rank: Super Contributor
timestamp: March 24, 2015, 12:24:27 am
content: I get the feeling you're more after a shunt regulator.

author: Rufus
author_rank: Super Contributor
timestamp: March 24, 2015, 12:26:02 am
content: Quote from: sebmadgwick on March 23, 2015, 06:33:26 pmBypasses itself with what?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 24, 2015, 03:25:25 am
content: Standard behavior in dropout (Vin < Vout(reg) + Vdropout) is to saturate the pass device. Mind that bipolar type LDOs may draw excessive "ADJ"/"GND" pin current in this condition.Check for a Vin-Vout DC transfer curve in the datasheet. Most likely, it will be off at low voltages (before the inner guts light up), then grab on and ramp up (in dropout), then regulate (Vout remains constant while Vin continues to rise).Tim

author: Gribo
author_rank: Frequent Contributor
timestamp: March 24, 2015, 09:37:37 am
content: TI has a buck regulator with such functionality, I don't remember the exact part number.
leakage current problem in EMG circuit  - Page 1
Forum section: electronics / projects

author: Moturki
author_rank: Newbie
timestamp: September 11, 2018, 04:12:43 pm
content: my project is designing EMG circuit and I will use (+9,-9 V) battery not power supply generator, but I doubt about the leakage current that could harm my body when recording EMG signal using surface electrodes, So is there any protection circuit should be used?

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 11, 2018, 10:56:30 pm
content: Even if you're not intending to sell your project, a safe approach could be to draw on the IEC 60601-1 standard, namely the part on "Patient leakage current".A very short summary would give you the following figures: 10 µA max allowable for type CF applied parts in normal condition and 50 µA max in single fault condition.Type CF basically means direct contact with the heart - for a purely skin contact electrodes device, the type BF is probably adequate, in which case you are allowed 10 times those figures, respectively 100 µA and 500 µA max. Also, if your electrodes are never in the chest area, type BF is definitely the right classification.Those are figures for a compliant medical device - in practice, you're probably not likely to feel anything under a couple mA, let alone be harmed, although you should obviously play it safe in the chest region.Don't think a device powered at +/-9V is necessarily safe with contact electrodes though: in case something went wrong with your circuit and you got up to 18 V across your electrodes; with good electrodes and a clean prepped skin, you can get impedances as low as a couple kOhm. Thus several mA. If on your leg or arm, it would probably just tickle, but if in another area, such as close to the heart, that could definitely hurt. Be also careful to avoid areas that could be close to any metallic implant (such as orthopedic screws and the like).You have to design your input stage to ensure no current above those figures can leak between the recording electrodes. 100 µA would be a good starting point IMO and should not be hard to achieve.In particular, beware of input bias currents. Also be careful if you design contains a so-called "right leg driver".Also, even if it's operated on batteries, if your device has any kind of interface to an external device, this interface should be isolated.As for protecting your inputs, ESD and overvoltage protection are good measures to make sure your device won't get fried while using it. ESD are very likely to occur when we mess with electrodes on the skin.You can get some ideas here:http://www.analog.com/en/analog-dialogue/articles/ecg-front-end-design-simplified.htmlEMG and ECG are very close - you may just need to adjust the gain/input signal range.
"Leakage" parameter of typical BJT - Page 1
Forum section: electronics / projects

author: CodiJack
author_rank: Contributor
timestamp: July 10, 2020, 03:36:46 pm
content: Hi.For a new design, I'm looking for "leakage" parameter of typical npn transistor like e.g. BC847B.I'd like to know what is collector current when transistor is off (base has the same potential as emitter) for a certain condition (defined Uce & defined temperature). To me it is Ices.In the many spec's of BJT it is defined only collector-base cut-off current (Icb0).Nowhere I could find Ices (base shorted with emitter).Is there a way to calculate it anyhow or is it the same as ...Icb0... (I doubt, but...)?

author: TimFox
author_rank: Super Contributor
timestamp: July 10, 2020, 04:18:09 pm
content: Ices should be close to Icbo, since the current gain of the device is removed due to the BE short. Iceo should be larger than Icbo, since the Icbo flows into the base and is amplified by the current gain. Checking a typical data sheet, however, I found Icbo > Iceo, but Icbo was measured at Vcb = 45 V, while Iceo was measured at Vce = 5 V.https://www.mouser.com/datasheet/2/68/2n2484-31162.pdf

author: CodiJack
author_rank: Contributor
timestamp: July 10, 2020, 04:49:22 pm
content: My heart tells me Ices>Iceo>Icbo.My engineering evil tells "base on what, did you come up to above conclusion?"To me floating emitter is no delivering carriers to collector, so only small base area via small contact on a "side of npn structure" (red path) deliver carriers.When emitter is connected to base, a total area capable of deliver carriers is much larger (green path), isn't it (mentioned above diode)?.Is it like I think or is it large simplification?
Learn from my fail: 8b/10b polarity swap - Page 1
Forum section: electronics / projects

author: jbb
author_rank: Super Contributor
timestamp: September 06, 2025, 02:04:56 am
content: I spent much of my week beating my head against a problem with my work project: capturing samples with a JESD204B ADC. I wanted to share my mistake here in the hope that other people can learn from it.The boil it right down, JESD204B converters transport the data as high speed (gigabit +) serial streams using 8b/10b coding; every 8 bit data byte - aka ‘octet’ - to be sent gets transformed into a 10 bit symbol for transmission. A lot of octets can be encoded into two different 10b symbols.It turns out that I had swapped the polarity of the high speed serial lines. You would think that it would simply not work at all… but as it happens, many of the 10b codes still make sense when polarity inverted. This meant that the link came up, and I got something which looked like a sinewave with some messed up bits. So if some data bytes come through OK and others are messed up in repeatable but unclear ways, check your polarity.

author: ejeffrey
author_rank: Super Contributor
timestamp: September 06, 2025, 02:31:47 am
content: Been there.It's easy to miss because another common high speed serial protocol PCIe supports auto-polarity detection -- the comma patterns that are often used in link establishment are distinguishable between polarity inverted versions. Generally you route the high speed pairs whichever way is best for signal integrity and then flip the polarity on chip. That is what you do for JESD204b as well, but you have to do the flip manually.What I have learned is essentially that if you generated sine wave data at a specific frequency, you are going to get that frequency out of the DAC no matter what's wrong. Lots of errors can look surprisingly "normal". So I try to use other patterns whenever possible. Sawtooth waves of a relatively low frequency are nice option, and generally testing a lot of different waveform types is best.

author: jbb
author_rank: Super Contributor
timestamp: September 07, 2025, 12:39:00 am
content: As it happens, using the test pattern modes of the ADC is what got me there.Edit: to clarify, the way I found my problem was by using the ADC test pattern modes, which send known data values down the JESD link
Learning analogue control theory - Page 1
Forum section: electronics / projects

author: Boscoe
author_rank: Frequent Contributor
timestamp: January 25, 2021, 11:42:11 am
content: Hi all,I can easily design circuits with basic control loops utilising op amps and I can create PID loops in digital systems however anything complicated in the analogue domain completely fools me. I'm talking about multiple loops and loops with many elements. I vaguely understand Routh arrays and other stability analysis methods. Does anything have any resources for learning this stuff from the ground up? I happy with anything such as books, youtube vids or online content but I'd prefer books.Thanks!Boscoe

author: Dave
author_rank: Super Contributor
timestamp: January 25, 2021, 02:35:27 pm
content: Here's a nicely writtenbookabout control systems theory.Brian Douglas, the author of the book, hosts aYoutube channelwhere he has lectures on the topic. The book actually came after the Youtube videos - it's basically a refined version of the information that was presented in the videos.

author: tmadness
author_rank: Regular Contributor
timestamp: January 25, 2021, 04:21:24 pm
content: I know that Design of analog CMOS integrated circuits by Behzad Razavi goes through control theory in a analog IC context for a few chapters.

author: jonpaul
author_rank: Super Contributor
timestamp: January 25, 2021, 05:51:14 pm
content: DelToro & ParkerPrinciples of Control System Engineering is the classic, in CCNY 1960s.https://www.amazon.com/Principles-Control-Systems-Engineering-McGraw-Hill/dp/B0000CKS38Jon

author: LaserSteve
author_rank: Super Contributor
timestamp: January 25, 2021, 08:04:05 pm
content: These are something I work on regularly. The scanner amp for a high speed galvanometer scanner. The scanner has a led and two or four photodiodes in its base with a moving flag. This forms a photosensor that sources differential currents as A and B feedback inputs. A closed loop current source linearizes the feedback sensor. Once you know that, you have low frequency damping, high frequency damping, servo as proportional. The other feedback means is EMF from across the Galvo coil. This is for a Cambridge Technology 6850 amp. The new ones are often DSP based. Capacitor and Resistor values change by model of galvanometer and its shaft inertia/resonances/ sensor gain. The next step up adds a notch filter assembly, not shown. An LM3886 is used as a power Op-amp.Enjoy....Steve

author: LaserSteve
author_rank: Super Contributor
timestamp: January 25, 2021, 08:16:00 pm
content: Two more scanner amps, these are for galvos or pen motors that have a torsion rod spring to return them to center. Back EMF is then used to derive the feedback.These are ancient, and designed by General Scanning Inc. Note the R-L bridge for damping derivation on the A-102.Enjoy...Steve
Learning project, Power supply design - Page 1
Forum section: electronics / projects

author: Rx7man
author_rank: Regular Contributor
timestamp: June 24, 2019, 07:14:12 pm
content: It's been 20 years since I took an electronics design course, I've watched a bunch of vids (especially EEVblog of course), and decided to at least exercise my mind a bit on this.. Yes, it would be perfectly easy to find a schematic online and copy it, but what would I learn.Looking to have about 5A 30V from this.All Zener diodes are 6.2V temp stabilized.Here's how I see the operation, apart from the obvious in the first pic.R1, R2 make a voltage divider circuit for the output, R3, VR1 make a complementary divider circuit, Op-amp is a comparator and drives the push-pull gate driver optocoupler to maintain a steady voltage through Q2For the current limiting part, Z4, Z5 are 6.2V temp compensated zener diodes, in conjuction with R7, R8 put the voltage from across the R6 current sense resistor into a usable range for the Op-amp, if the current is above the setpoint set by VR2, the op amp activates Q3 which grounds out the reference voltage of the voltage control circuit shutting down the output... There's also an indicator LED that's driven when this happens.A few pitfalls I know I'm at least attempting to mitigate... Vgs of Q2 is usually about 20V max, so the optocoupler is between the 36V rail and 12V rail, but Z3 brings the low side voltage to about 18V, leaving 18V across the optocoupler.. I may add a 20V zener across the OC as well just as a secondary measureAD8086 is a fet rail-rail opamp, 145 mhz (3db).. the only thing that I see in the datasheet is the differential input voltage at 1.8V, Am I going to have to clamp this? pair of diodes each way would do it wouldn't it? Especially concerned about the it on the voltage regulator side.A3210 (aka J312) Optocouplers are designed for gate drives, and have input hysteresisZ1, Z2 protect the op amp inputs, especially at startupMost of the resistance values are really roughly calculated, probably will add some trim pots here or there for fine adjustments

author: Kleinstein
author_rank: Super Contributor
timestamp: June 24, 2019, 07:50:00 pm
content: It's quite unusual to build a SMPS by hand instead of using a specialized chip. I don't understand the circuit, but the gate drive to Q2 looks wrong. Usually the gate drive with bootstrapped supply needs to be relative to the source side, not drain. There also needs to be some free-wheeling diode at L1.With such a complicated circuit it is a really good idea to run it in a simulator first.

author: Rx7man
author_rank: Regular Contributor
timestamp: June 24, 2019, 07:51:55 pm
content: you're right, I got that backward.. I'll go fix itYes, I'd certainly want to run it through a simulator first as well
LeCroy 8500 ProBus RF-Connector, SMB? - Page 1
Forum section: electronics / projects

author: sixtimesseven
author_rank: Frequent Contributor
timestamp: March 31, 2019, 06:01:51 pm
content: I was looking at the LeCroy 8500 or the Disk Analyzer Variant (DDA-5005A) since they seem to be pretty reasonably priced (<2000 Dollars) for a 5Ghz scope and have nice deep memory. Anyway, annoyingly they use these adapter things (LPA-SMA-A) for probes and more importantly, SMA connectors.https://www.ebay.de/itm/TELEDYNE-LECROY-LPA-SMA-A-Oscilloscope-Probe-Pro-Link-To-SMA-Adapter/113644713057?hash=item1a75c0b461:g:6qIAAOSw19dcZ5xRHowever, they are like 185 Dollar a piece of what seems to be a straight trough connector of the ProBus Pin header, a RF adapter and maybe a resistor to set the probe type to 1:1. EEPROM seems to be overkill really (?) There is a thread on the ProBus / Pinheader here:https://www.eevblog.com/forum/testgear/lecroy-probus-reverse-engineering/That part is easy, but I'm not exactly sure what RF connector is used. From the looks of it it seems it is just a standard SMB connector. So my idea is to print a little adapter plate and use a SMB to SMA bulkhead adapter:https://www.mouser.ch/ProductDetail/Amphenol-RF/242182?qs=d6ov5MOrwvH2i98YkROmQg==Would be really interested whether it is indeed just a SMB connector?Also, if anyone knows of a teardown of one of this adapters I would be really interested

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 01, 2019, 12:50:45 am
content: its BMA connector. i've made some prototype for compatible LPA-BNC and LPA-SMA adapter as can be seen here...https://www.eevblog.com/forum/buysellwanted/fs-lecroy-dda-5005-dso-5ghz-20gsps-xxl/msg2217855/#msg2217855still under development esp the 6 pins connector that is like pig to get the supply from... costed me $300 just to know whats inside an LPA-BNC bloody damned thing. not anything inside not even a resistor, just probably a high quality custom made straight through BMA to BNC. i suspect the same for LPA-SMA i'm not going to waste any money on that. Lecroy WM scope will default to 1X attenuation anyway. i'm reselling the LPA-BNC in ebay i think i'm the last mohican selling it at current time...the first man afaik who ever asked such a question in this forum is this...https://www.eevblog.com/forum/testgear/type-of-input-connectors-on-a-lecroy-dda-5005a-scope/msg1797743/#msg1797743and then there's...https://www.eevblog.com/forum/projects/lecroy-connectors/msg2167048/#msg2167048and as any others you already know...
LeCroy USB 3.0/3.1 PD video - Page 1
Forum section: electronics / projects

author: bson
author_rank: Unknown
timestamp: January 24, 2022, 07:19:54 pm
content: For those of us who don't actively work with USB PD, I found this useful to get up to date.https://go.teledynelecroy.com/l/48392/2022-01-18/8crhxt?utm_source=Email&utm_medium=Email&utm_term=USB&utm_content=On-Demand+Webinar+Registration&utm_campaign=22-01-24+USB+Power+Delivery+3.1+Round-up+Webinar+On-DemandApprox 45 min.
LED adds noise to power rails? - Page 1
Forum section: electronics / projects

author: mkiijam
author_rank: Regular Contributor
timestamp: April 08, 2024, 03:06:59 pm
content: I was thinking about adding little indicator lights to my audio circuit's +/- 15V supplies (LDO regulators), but it seems like I have heard they might add noise? I was going to place them right after the regulator output to ground with current limiting resistors, of course.

author: tooki
author_rank: Super Contributor
timestamp: April 08, 2024, 06:37:19 pm
content: I can't imagine why they would.Are you sure you're not confusing switching noise caused by LEDlighting? (Or to be specific, the power supplies for said lighting.) That has nothing to do with a simple indicator LED, which is pure DC.

author: Someone
author_rank: Super Contributor
timestamp: April 08, 2024, 11:11:20 pm
content: Noise of what magnitude? It's mostly quantifiable.You can even measure the currentsuppliedby the LEDs when they are lit by an external source.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: April 08, 2024, 11:57:51 pm
content: Quote from: mkiijam on April 08, 2024, 03:06:59 pmIf thelittle indicator lightsare simple LEDs with series resistors, you will be fine.You can even buy LEDs with inbuilt resistors, tho they are less common.It is the active switching LED drivers that can have pulsed currents, that can give noise problems.

author: DimitriP
author_rank: Super Contributor
timestamp: April 09, 2024, 12:36:43 am
content: Fun reading:https://www.diyaudio.com/community/threads/some-noise-measurements-for-leds-and-zener-diodes.35821/
LED Arrary HUB-06 Protocol/Pinout Question - Page 1
Forum section: electronics / projects

author: edtyler
author_rank: Contributor
timestamp: September 17, 2023, 04:43:43 am
content: Hi,I recently picked up a 30x30 LED Arrary labeled JHG-P8.33(3in1)-2M-5S-V1.0D at a ham swap meet.So far, there seems to be no available information about the protocol called HUB-06 that seems to use a 2x10 .1inch header. There are other protocols with the HUB- prefix, but it is unclear how they relate to HUB-06. Normally, I would disassemble the device and trace the circuits after identifying the logic components, but the entire array is nicely potted in epoxy to make it weatherproof. Removing the epoxy would likely damage or destroy the array.Does anyone have a pointer to a description of the HUB-06 protocol and also the pinout for the 2x10 connectors.Note: there are two logic (2x10) connectors and two power supply connectors on the 30x30 assembly.Thanks,Dale

author: coromonadalix
author_rank: Super Contributor
timestamp: September 17, 2023, 05:50:44 am
content: never heard of a HUB06This site list tons of hub card with some pinoutshttps://www.ledcontrollercard.com/english/led-hub-card.htmland please post images, chinesium stuff like tiles, sometimes give nothing when you do some searchnormally the lowest is a HUB 08EDIT oh there is some HUB 03 and 04never saw theses .normally you haveRedGreenBlueClkLatchOeand sometimes datalines likeRD1 RD2 ...BD1 BD2 ...GD1 ...CHECK HUB 73and finaly, an pixel is composed of 3 or 4 leds or SMD like RGB W or RGB, unless you are monochromeyou have name like p3 p4 p5 p7.68 p10 p16 etc ... normally it is the pixel group size IE: p10 is 10mmAnd you normally need a dedicated controller for theses ...ORand finally some hints and or projects :https://www.adafruit.com/product/607https://learn.adafruit.com/32x16-32x32-rgb-led-matrix/
LED array on constant current driver? - Page 1
Forum section: electronics / projects

author: BTXX
author_rank: Newbie
timestamp: August 31, 2018, 04:55:31 am
content: Hi guys and gals,so i need to design an LED array and its been a while since ive done any electrical work.heres my setup.If i need each led to run at 70mA, what do I configure the constant current driver output for?,would it be 420mA (70mA x 6) , as I have 6 parallel groups of 3 LEDs in series?and secondlywith a constant current driver does that mean if one LED fails and goes open circuit, the current would increase on the other LEDsthanks.

author: Zero999
author_rank: Super Contributor
timestamp: August 31, 2018, 08:14:34 am
content: Yes, such an arrange means one LED failing will result in a greater current for the other LEDs. The forward voltage of all the diode should also be closely matched, which in practice is difficult/impossible so it's a good idea to add a low value resistor in series with each string.
LED Battery - Page 1
Forum section: electronics / projects

author: Jon86
author_rank: Frequent Contributor
timestamp: August 05, 2013, 11:46:16 pm
content: I'm looking for a battery to power a 3.6V 3A Cree LED for roughly two hours or so. Can anyone suggest the cheapest way to do it?I was thinking of maybe Lead acid, but that seems a little expensive. Weight doesn't matter, just price really.Any help greatly appreciated, thanks.

author: ddavidebor
author_rank: Super Contributor
timestamp: August 05, 2013, 11:57:50 pm
content: Quote from: Jon86 on August 05, 2013, 11:46:16 pmLead acid car batteryNo dubt

author: echen1024
author_rank: Super Contributor
timestamp: August 06, 2013, 12:06:20 am
content: Lead Acid. Cheap and has a lot of capacity.

author: mariush
author_rank: Super Contributor
timestamp: August 06, 2013, 12:54:16 am
content: I agree, lead acid battery would be the easiest followed by maybe one of those lithium batteries for toy airplanes .Cheaper... and I'm not even sure it would be cheaper....maybe one of those laptop batteries you find on eBay cheaply?maybe if you go and buy 20-30 alkaline AA batteries and put them in series and parallel so they would share the current? Seehttp://www.batteryshowdown.com/results-lo.htmlandhttp://www.batteryshowdown.com/results-hi.html... they last hours at 200mA draw and about half an hour at 1A...

author: Fsck
author_rank: Super Contributor
timestamp: August 06, 2013, 12:59:04 am
content: Lead acid if you have to buy.However, you may be able to find thrown away busted laptops and salvage armies of 18650 cells which would be free.

author: Jon86
author_rank: Frequent Contributor
timestamp: August 06, 2013, 10:07:52 am
content: Lead acid seems a little expensive really, to get a good 6Ah one will cost £10, then I'll have to somehow regulate that voltage down for the LED, that costs more...The 18650 cells sounds promising, which laptop batteries would contain them?Also, what type of lithium batteries for toy airplanes?Thanks for the help, I'll get back to researching

author: Psi
author_rank: Super Contributor
timestamp: August 06, 2013, 10:52:41 am
content: One cell hobbyking (or other) lipo and a large wattage resistor.The brightness will fade though, as the resistor will be spec'ed for 4.1V and the Vbatt will drop as it discharges

author: ddavidebor
author_rank: Super Contributor
timestamp: August 06, 2013, 12:06:33 pm
content: Quote from: Jon86 on August 06, 2013, 10:07:52 amWell you should use a regulator anyway.Lead acid are simple to use and charge, litium need a proper charger or they became quite dangerous
LED Boost converter? - Page 1
Forum section: electronics / projects

author: jmole
author_rank: Regular Contributor
timestamp: October 18, 2013, 02:27:32 pm
content: Looking to drive 16 LEDs in series from a 48V supply, so I need a boost converter to get the supply to around 60V. However, I also want very responsive dimming via PWM.I've been doing some reading online, and found that LED Boost converters aren't really usable with high PWM frequencies:http://www.eetimes.com/document.asp?doc_id=1273256So I'm now wondering if I should use a boost converter to create the 60V rail, and use a buck converter for the LED driving off the rail. I do realize this will lower the efficiency, but will there be any other side effects as well? I.E., is this no better for fast PWM than just using a LED boost converter?