hybridfree/eevblog-posts huggingface dataset:
deciphering sequencer circuit logic  - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: September 20, 2024, 03:23:57 pm
content: Hello, There is an intresting circuit shown in the photos below which is a sequencer circuit.Its suppose to bias by the laws shown in the table below.There are plenty of BJT with diode compbinations.Could you explain the general logic of this circuit?Which subcircuits it consists of and what each sub circuits does?Thanks.

author: ledtester
author_rank: Super Contributor
timestamp: September 20, 2024, 05:08:06 pm
content: Can you upload the LTspice .asc file? What kind of "sequencer" is this?

author: ajb
author_rank: Super Contributor
timestamp: September 20, 2024, 05:31:49 pm
content: The sequencing is handled by the delay parameters in V3, V4, V5, and V6.The remaining circuitry is a combination of level shifting and voltage/current sources. You can easily split it into three subcircuits if you look at which components share connections that aren't just ground or power (so connections to V1/V2). Or if you look at the inputs and outputs: VG_ON+VG_DAC -> VG, VC_ON -> VC, and VC_ON->VD.U1, U2, and U3 are adjustable voltage references, and D1 and D2 are zener diodes used as fixed voltage references.

author: Someone
author_rank: Super Contributor
timestamp: September 20, 2024, 10:10:55 pm
content: Quote from: ledtester on September 20, 2024, 05:08:06 pmLook back through the OP's posts to get some context. Some sort of reverse engineering where they present circuits of unknown origin and ask us to explain them or redesign them for some non-specific (and likely wildly incorrect) RF FET biasing.

author: ArdWar
author_rank: Frequent Contributor
timestamp: September 20, 2024, 11:19:41 pm
content: This is technically not a sequencer since it does not generate the correct sequence/timing itself in response to any output level. It only generate the voltages in response to external triggers.Anyway, OP's original goal was reasonable. It's just that they choose the most absurdly overcomplicated unconventional way to achieve the goal. This isn't XY problem anymore, this is -ln(X + 4(e-X- 1)) Y problem.I'd really like to see how it worked out of you actually use this to bias a RF amplifier...

author: john23
author_rank: Frequent Contributor
timestamp: September 21, 2024, 01:41:13 pm
content: Hello Ajb,could you draw on the circuit , where is the level shifter and where is the current source?"level shifting and voltage/current sources. You can easily split it into three subcircuits"Thanks.

author: Andy Chee
author_rank: Super Contributor
timestamp: September 21, 2024, 02:04:04 pm
content: Quote from: ledtester on September 20, 2024, 05:08:06 pmThe sequencing table appears to be an extract from a Qorvo GaN device datasheet, for example:https://www.qorvo.com/products/d/da003659(sequencing table on page 20)I'm not sure of the exact device the OP is referring to.
Decode OBD2 data so can put into spreadsheet - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: January 13, 2017, 01:26:11 am
content: Plugged an ELM327 OBD2 dongle into the car, ran OBD Auto doctor on the laptop and recorded several different parameters at approx 1/2 second intervals. The data looks like the following:Code:2017-01-13 11:51:30>>010C2017-01-13 11:51:31<<C4B192410C16A9132017-01-13 11:51:31>>010D2017-01-13 11:51:31<<C3B192410D2B7F2017-01-13 11:51:31>>010B2017-01-13 11:51:31<<C3B192410B34862017-01-13 11:51:31>>010F2017-01-13 11:51:31<<C3B192410F499F2017-01-13 11:51:31>>010D2017-01-13 11:51:31<<C3B192410D2B7F2017-01-13 11:51:31>>010C2017-01-13 11:51:32<<C4B192410C15AA132017-01-13 11:51:32>>01052017-01-13 11:51:32<<C3B19241057DC92017-01-13 11:51:32>>010C2017-01-13 11:51:32<<C4B192410C12BE242017-01-13 11:51:32>>010D2017-01-13 11:51:32<<C3B192410D2C802017-01-13 11:51:32>>010B2017-01-13 11:51:32<<C3B192410B2375Apparently there is a 3 byte header, data and then a checksum.How could I possibly sort this out into some values that could be pasted into a spreadsheet and then graphed?I thought the software could save the sensor values in a .csv file but apparently it does not.

author: Circlotron
author_rank: Super Contributor
timestamp: January 13, 2017, 02:00:50 am
content: http://dthoughts.com/blog/2014/11/06/obd-scanner-using-elm327/Getting there, but everyone's input welcome.
Decoding the 4004 - SGT Pass Transistors and Latches - Page 1
Forum section: electronics / projects

author: PickledPhil
author_rank: Newbie
timestamp: October 28, 2022, 11:38:06 am
content: Hi AllI've been looking at the transistor level schematic for the 4004 processor and been trying to make sense of it.A lot is fairly self-evident, but in many places there are constructs similar to that shown in the attached image and I'm wondering what this does exactly. It seems to me that this is a type of latch where T1 acts as a pass transistor when B is high, and a charge is stored on the gate of T2 once B is low and T1 is off, preserving the output. Would I be right in this assumption or any other thoughts?!
Deconstructing a Peltier module - Page 1
Forum section: electronics / projects

author: rhb
author_rank: Super Contributor
timestamp: May 13, 2018, 07:11:30 pm
content: Has anyone done this? I just cut one of the $3 Chinese units apart. This caused a lot of damage, but they appear to be constructed of small cubes which have been reflow soldered in place. So it would appear that a hot plate would be an effective way to disassemble them.The reason for doing this is the RF power sensor thread:https://www.eevblog.com/forum/metrology/rf-small-power-thermal-sensor/msg1523353/#msg1523353The objective is to hold one end of a stack of SOT523 transistors and spacers at constant temperature with a resistor at the other end which is also held at constant temperature by a DC bias which is reduced when RF heating takes place. The reduction of the DC bias is a direct measure of the RF power if the sides of the stack are perfectly insulated. Aerogel powder is cheap and should be pretty close to perfect insulation.As a consequence, I want an SOT523 or similar size Peltier cooler.

author: CopperCone
author_rank: Super Contributor
timestamp: May 13, 2018, 08:07:28 pm
content: the chinese ones use an odd low temperature solder, I believe the same kind sometimes used for roofing work. I forgot the composition.Another option for you might be to take a tile saw (or better yet, thin diamond saw on a dremel) and carefully cut a section of the peltier module apart to get a doped pair, then solder wires onto that.Typically they will be lapped after they are soldered together, you need very flat dimensions for effective heat sinking and you can't expect ceramic plates to line up in parallel after being soldered (like spring manufacture). If you cut a section out, you can maintain this convenience.Now I want to cut myself out a tiny peltier. My expensive dremel diamond saw and proxxon dremel stand finally has meaning to its life.
decoupling a high power signal? - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: October 08, 2013, 12:09:41 am
content: I would like to decouple a high power signal (200mA rms) to remove offset errors from the amplifier.Is it possible to use some kind of capacitor (tantalum slug?). Or is a transformer required?The signal is 40kHz.

author: baldengineer
author_rank: Contributor
timestamp: October 08, 2013, 01:12:01 am
content: Why do you consider 200mA to be "high power? That sounds pretty low to me.

author: SArepairman
author_rank: Frequent Contributor
timestamp: October 08, 2013, 04:37:04 am
content: Because I don't have ANY experience with signals that are not just fed into another op-amp.Will a regular decoupling capacitor work?

author: kalobg
author_rank: Newbie
timestamp: October 08, 2013, 05:32:51 am
content: Quote from: SArepairman on October 08, 2013, 04:37:04 amCapacitor should be ok for amplifier offset errors. 200mA is lower power range, but the cap will accomplish what you want regardless if 200mA is high or low power--just make sure you pick a cap appropriate for your application.
decoupling between the rails? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: November 15, 2023, 12:51:02 am
content: If you have a dual rail PCB, with negative and positive DC supply (amplifier), assuming you already have alot of decoupling, what is the effect of putting a capacitor between rails? Kind of like common mode.Is this practice evaluated somewhere?This PCB has some fat traces running near each other, its possible to just put a bunch of caps there between + and -.

author: temperance
author_rank: Super Contributor
timestamp: November 15, 2023, 01:35:14 am
content: It depends on what you want / must filter. Without any other input it's impossible to say what will or will not work for you.Here is a presentation about filter / decoupling related to switching power supplies and the simulation of common and differential mode noise with LTspice.https://www.youtube.com/watch?v=u-WXTROc3lE&ab_channel=W%C3%BCrthElektronikGroupYou will see there are limits for both type of noise.

author: dobsonr741
author_rank: Frequent Contributor
timestamp: November 15, 2023, 01:57:03 am
content: More details would be helpful:Amplifier for what frequency range, what signal level, what gain, what power supply feeding the rails? Is the input ground referenced or diffrerential?

author: David Hess
author_rank: Super Contributor
timestamp: November 15, 2023, 02:06:35 am
content: Quote from: coppercone2 on November 15, 2023, 12:51:02 amDecoupling is about shorting out the return currents, so if those are between the positive and negative supply, then the capacitor should go between the positive and negative supply to reduce the loop area between the source and load as much as possible.Check out Analog Devices application note 202 for a discussion about this.

author: coppercone2
author_rank: Super Contributor
timestamp: November 15, 2023, 02:23:55 am
content: ok that makes sense.https://www.eevblog.com/forum/beginners/bypass-caps-opamps-and-two-power-rails/

author: ejeffrey
author_rank: Super Contributor
timestamp: November 15, 2023, 02:48:03 am
content: Only one of the pass transistors is significantly on at a time. The current flows from the power rail (+ or -) through the pass transistor to the load and to wherever the load returns, usually ground. So usually on a split rail opamp power supply, decoupling between each supply and ground is ideal, even though the opamp itself doesn't have a ground reference.
Decoupling Cap Size for Fine Pitch BGAs - Page 1
Forum section: electronics / projects

author: bhj99
author_rank: Contributor
timestamp: August 19, 2024, 11:18:45 pm
content: Hi all,I wanted to get some opinions on the max package size for decoupling caps when used on fine pitch BGAs in packages like WLCSP (0.4 mm and 0.5 mm pitch specifically). I am working on a design that uses a Microchip PolarFire SoC (0.5 mm pitch) and DDR3 memory chip (0.4 mm pitch) I believe the recommended is 0201 for these devices; however, I typically refrain from passives less than 0402 for improved manufacturability and producibility but this can create challenges in the PCB routing. The PCB design will be HDI so via in pad will be used. I would appreciate any thoughts and experiences from others on this topic. Thanks!

author: thm_w
author_rank: Super Contributor
timestamp: August 20, 2024, 12:42:45 am
content: The difference here looks minimal:https://www.rs-online.com/designspark/downsizing-to-smaller-mlccs-what-you-should-knowBut you could look up the actual parts you are using.There is obviously a difference in inductance, ~100pH or whatever.In the user guide there are 0402's mentioned for the 1mm pitch, so I would expect it not to matter for your application:https://ww1.microchip.com/downloads/aemDocuments/documents/FPGA/ProductDocuments/UserGuides/PolarFire_SoC_FPGA_Board_Design_Guidelines_User_Guide_VB.pdf

author: bhj99
author_rank: Contributor
timestamp: August 20, 2024, 12:53:56 am
content: Right, but Microchip also recommends 0201s for 0.8mm and down to 0.5mm (what i am using).

author: thm_w
author_rank: Super Contributor
timestamp: August 20, 2024, 09:11:22 pm
content: OK but think about it more, is there an actual difference between the ICs? If I have a 555 in DIP8 and SOIC8, the die inside is the same right.They probably chose it as its a better fit between the pins.

author: Siwastaja
author_rank: Super Contributor
timestamp: August 22, 2024, 06:27:41 pm
content: Functionally, and from parasitic inductance viewpoint anything from 01005 to probably even as big as 0805 goes no problem, but if you are trying to use too big of a package,youwill be first to notice, painting yourself into corner in routing.There is no generic advice because pitch isn't the only factor; some parts have more power pins needing bypassing than others. Some might have most of the power pins near the perimeter, easy to place next to the chip. In some cases you can leave unconnected pins, leaving room for routing. And sometimes you can't, need to pepper gazillion of capacitors all over the bottom layer.Maybe start routing using 0402 caps and when you see "oh crap these won't fit" or "I need to fan these out way too far", switch to 0201. If a CM handles fine-pitched BGA no problem, they should also be able to handle 0201 passives.
Decoupling caps with series inductor - Page 1
Forum section: electronics / projects

author: loudaslife
author_rank: Newbie
timestamp: August 05, 2020, 06:17:53 am
content: I've been looking at theNXP BGA3018 datasheet, and I'm a bit confused by the application circuit on page 10.My understanding of decoupling caps is that low value/small package caps are chosen to minimize parasitic inductance. If so, why place 10nF and 100pF caps on the other side of L2, which has 3-4 orders of magnitude more inductance than any ceramic cap? If you look at ESR instead of inductance, the story is the same. It seems to me like you may as well just use one large capacitor (maybe 1uF) instead.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 05, 2020, 06:52:19 am
content: Yes, at high frequencies there is an inductance divider from the RFC to the caps, and between caps. A large attenuation is desired, to keep RF out of the power supply.A large capacitor will have the same ESL (or more, because it's physically larger), so will perform worse.Tim

author: tggzzz
author_rank: Super Contributor
timestamp: August 05, 2020, 07:03:38 am
content: Quote from: loudaslife on August 05, 2020, 06:17:53 amYou would benefit from doing a quick simulation of the relevant parts of the circuit (an AC sweep in this case). LTSpice is a good starting point, but I expect there are online simulation programs.As for the different sizes of capacitor, the answer will be found in the datasheets for different capacitors. The impedance vs frequency is the key point. For bonus points, find the equivalent parasitic inductance and capacitance, and include that in the simulation.

author: Kleinstein
author_rank: Super Contributor
timestamp: August 05, 2020, 07:22:06 am
content: The inductor L2 is part of the amplifier, not part of the decoupling. Decoupling is there to keep the RF out of the supply. I am not so sure the 100 pF really have an effect or are only there because of tradition from times when a 10 nF cap was large.

author: loudaslife
author_rank: Newbie
timestamp: August 05, 2020, 08:01:53 am
content: For some reason I hadn't even thought about keeping noise out of the power supply, I was only thinking about it in terms of providing a stable voltage to the IC. That makes much more sense, thanks.

author: srb1954
author_rank: Super Contributor
timestamp: August 05, 2020, 09:09:44 am
content: In this case the inductor is not for decoupling but supplies the DC supply current to the amplifier while also presenting a high RF impedance to minimise loading on the amplifier output. A resistor could be used in this position but the available amplifier gain would be lower and a higher supply voltage would be required.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 05, 2020, 09:44:42 am
content: The reason for the inductor is not to supply stable voltage, but stable current. It's not so much an IC as a prebiased transistor.Tim
Decoupling Inductors used in SMPS - Page 1
Forum section: electronics / projects

author: thereza
author_rank: Contributor
timestamp: January 10, 2014, 06:15:09 am
content: I'm working on a new board and picked an inductor for a switching regulator, but was surprised to find that it's a self-proclaimed "Decoupling Inductor". What makes an inductor specially adapted to decoupling applications, and can I not use this for a sm power regulator (FT440).http://www.tdk.co.jp/tefe02/e533_mlz_h.pdfReza

author: Circlotron
author_rank: Super Contributor
timestamp: January 10, 2014, 11:34:06 am
content: That datasheet lists inductors only going as high as 10 uH. That's not very big. Also they do not look like they have a "closed" magnetic circuit but instead let the flux exit one end of the inductor and find its way through the air to the other end. They would have some degree of HF filtering but not very suitable as an energy storage inductor like you want. These general type may be more suitable ->http://image.made-in-china.com/2f0j00rCStHivKfezO/SMD-Power-Inductors-SPRH127-.jpg

author: thereza
author_rank: Contributor
timestamp: January 10, 2014, 09:51:25 pm
content: Great explanation - thanks.Reza

author: Ghydda
author_rank: Regular Contributor
timestamp: January 12, 2014, 09:25:03 pm
content: Quote from: thereza on January 10, 2014, 06:15:09 amDecoupling usually refers to ways of controlling/limiting EMI.Inductors for decoupling usually needs to behave as an inductor at 10s and/or 100s of MHz.Inductors for smps-purposes usually do not go much above a few MHz before stray capacitance takes over.
Decrease rise time of Rb oscillator - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: May 27, 2013, 03:19:35 pm
content: Hi.Warning, this question is very vague and conceptual.I've been presented the following problem:A rubidium oscillator needs to drive a 50 Ohm load, but is unable to do so because it has a slow rise time and a small amplitude.I have devised a simple FET amplifier to increase the amplitude and a comparator to decrease rise time.However I am told that there might be a better way of decreasing the rise time than with a comparator. What might it be?I will make measurements tomorrow and try to give some numbers.Regards.

author: PA0PBZ
author_rank: Super Contributor
timestamp: May 27, 2013, 06:58:19 pm
content: Apart from the question what the risetime got to do with the ability to drive a 50 Ohm load I think a comparator would be just fine, assuming we are talking square waves isn't it? And while you have the comparator, why do you need the FET amplifier? If you are talking 5 volt try to find a comparator with 100 mA drive current and you are done.

author: muvideo
author_rank: Frequent Contributor
timestamp: May 27, 2013, 11:44:00 pm
content: Hello, if your Rb has a sinewave output you can find simpleand tried clock shaping circuits, based on comparator, orfilter + logic gate, or isolated, dpending on your needs:http://www.ko4bb.com/Timing/ClockShaper.phphttp://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:clock_shapershttp://www.ko4bb.com/~bruce/CLKSHPR.htmlI've used this circuit, Q4 Q8:http://www.flickr.com/photos/14336723@N08/8297438155/#If your source is an FE5680A, it's output it's a digital signalfiltered by an RC filter, you can open it and disconnect thecapacitor to have your nice squarewave, some resources:http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_faq

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: May 28, 2013, 12:57:14 am
content: Hi,There are two ways to do this:1) Is to use some form of comparator. Apply a fixed voltage to one input and the sinewave to the other input.2) The second way is to amplify the signal until it clips.The advantage of the second method is that it offers reduced jitter.There are parts that are specially designed for this:http://www.linear.com/product/LTC6957-1You should also read the design note:http://cds.linear.com/docs/en/design-note/dn514f.pdfPhase noise on the a sinewave becomes jitter on the edges of a squarewave so the terms are similar.Jay_Diddy_B

author: Unknown
author_rank: Unknown
timestamp: May 28, 2013, 09:40:49 am
content: Thank you for your replies.The Rubidium standard used is the GRCLOK-1500 (datasheet:http://www.spectratime.com/documents/iSync_GRClok-1500_Spec_060513.pdf)It outputs a sine wave. The output impedance of the 10MHz clock is 50 Ohm +- 20%, 60 Ohms taking worst case scenario. The datasheet says that it is 0.5Vrms. I have made measurements on the unit that I have and the signal is 3.125V peak to peak.The clock needs to drive three 50 Ohm loads so an equivalent of a ~16 Ohm load. It also needs to be converted into a square wave with a rise time of around 10 ns.
Decreasing the current of CCFL Inverter - Page 1
Forum section: electronics / projects

author: thealienx
author_rank: Newbie
timestamp: January 10, 2017, 01:35:39 pm
content: Hi,Sorry if this is not the right lane.i have a ccfl inverter with ccfl tube, picked from a scanner unit.i want to use the inverter circuit for a non lethal shock gun.i have gathered some information on safe range of current in human being.------------------------------------------------------------In general for a normal human:1mA(mill Ampere) or (.001A) of current can be felt.5mA of current can be painful.10–15mA, the person loses muscle control.If its above 50mA then it would fatal.100mA above would be lethal.------------------------------------------------------------Please see pic for Inverter.some technical articals says about 5ma is used to activate ccfl tube.i want to decrease the current to a safe level (1 0r 2 ma) for my project. can someone help me in how to do?Thanks

author: Zero999
author_rank: Super Contributor
timestamp: January 10, 2017, 07:19:06 pm
content: Quote from: thealienx on January 10, 2017, 01:35:39 pmThe figures you've quoted are for power line frequencies (50 to 60Hz). The CCFL inverter will output a much higher frequency (>20kHz) which is less likely to cause an electrical shock, even at greater currents than those listed above. The only hazard is heating: it can badly burn you and penetrate very deeply into the flesh.QuoteYou could reduce the value of the capacitor in series with the tube (the blue one in your picture) but 2mA at 20kHz would just feel like touching a hot object, if the the contact area is small, or nothing at all, if the contact area is large.To build a shock circuit, you'll need to add a rectifier and smoothing capacitor to the output. A voltage multiplier would be a good idea, as higher voltages are required to penetrate think clothing. The capacitors shouldn't be too large, otherwise it becomes deadly.

author: wraper
author_rank: Unknown
timestamp: January 10, 2017, 07:23:08 pm
content: This is completely wrong thing to be used as electric shocker. Moreover inverter is not made to run open or short, it will fail very soon. The only thing will happen to you if you try to use it on someone, it will end up in your butt.
Decyphering wording in IEC 64547 regarding Burst Testing - Page 1
Forum section: electronics / projects

author: twistedresistor
author_rank: Contributor
timestamp: August 22, 2018, 09:47:26 am
content: Hi all,I am a bit thrown off by the wording in IEC 61547 (EMC immunity of general lighting) wether Burst (EFT) testing on DC power power ports is applicable or not.I'd like to ask you about your interpretation of the following footnote in Table 5:"[Fast Transients] Not applicable to equipment not connected to mains while in use"So my possible interpretations:My device must be supplied via 24V DC (no Earth/PE)1) Argue that it is not connected to mains, because you need a 24 V Power supply, so not applicable.2) Argue that you need a 24 V Power supply, which is plugged into mains; so my device is technically connected to mains, so it is applicable.What do you think?

author: Rerouter
author_rank: Super Contributor
timestamp: August 22, 2018, 09:57:47 am
content: I would say yes if your intended use case was for a mains powered PSU.If it was intended for automotive, e.g. battery powered, I would say No, however even this use case has similar requirements, e.g. Load dump.
Dedicated Resistor Checker - Page 1
Forum section: electronics / projects

author: easilyconfused
author_rank: Regular Contributor
timestamp: July 13, 2010, 08:42:18 pm
content: I don't know if I'm the only one but it's kind of a pain in the ass to pull out my meter over and over again to verify resistors. I have no idea what it would take to build a auto-ranging tester that could be screwed to the wall above my bench. But that's what I would like. It would have a metal bail that simply lifted up. Then gravity would apply pressure to the resistor leads. One would push the on/off button which would go off after a few minutes. I suppose a capacitance feature would be a logical extension of the idea. I'm just a beginner doing a lot of breadboarding. If it's already available can someone tell me where to get one.

author: Unknown
author_rank: Unknown
timestamp: July 13, 2010, 09:01:06 pm
content: It's probably hard to build one for less than a (used) auto-ranging DMM. I would just hook a custom test fixture to an existing meter. Your idea won't work for components in a circuit (need floating leads for that). Just a second DMM permanently set to resistance might also work, guess why many people have more than one DMM (although not all of us are as insane as Dave, at least in this regard). Learning resistor color codes might also be a solution.

author: EEVblog
author_rank: Unknown
timestamp: July 13, 2010, 10:04:40 pm
content: If you want convenience then it's probably bets to get a cheap RC or LCR meter with the plug-in spring terminals for components. Then you don't have to muck around with test leads.Many are manual ranging though unfortunately.Or just get a small autoranging meter with short (few inches) alligator clip leads and stick that on the wall.I believe you can also get banana to component terminal like adapters of some sort.Dave.

author: easilyconfused
author_rank: Regular Contributor
timestamp: July 14, 2010, 01:02:29 am
content: Quote from: EEVblog on July 13, 2010, 10:04:40 pmIn the time that passed since I put up the post I thought about banana-to-component (not knowing if such a thing exists), and then thought about how nice the springs work on my Radio Shack Learning Lab. So I guess great minds think alike (right!). Either way it looks like using an existing meter is the best way to go. Thanks

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 14, 2010, 10:18:56 am
content: Quote from: easilyconfused on July 14, 2010, 01:02:29 amIts all about the "Relative" = or Zero Ohm function ..With out it , every measurement at resistors , its not that automated as process.Staying next to "ready made" solutions , you have to worry less about the accuracy factor too.
Dedicated scan generator IC vs DACs for scanning electron microscope - Page 1
Forum section: electronics / projects

author: Nerdbert
author_rank: Newbie
timestamp: November 21, 2018, 11:04:08 am
content: Hi everybody,for my work at university I'm basically building a scanning electron microscope. For that I'm in need of 2 phase coupled triangle or sawtooth waves to drive the deflecting elements, ideally with a sync pulse when the wave reaches the maximum. That could however be done afterwards with a comparator.The maximum needed frequency would be in the 100 kHz range. An adjustable amplitude and offset would be helpful, but that could also be done with an op-amp circuit afterwards, I guess.Finally there is no need for high voltage since we are going to use high voltage amplifiers.The question is, are there any dedicated ICs that do that sort of thing? Maybe something that was used in CRTs?Or would I be better off just using some ADCs?Thank you very much for your help.

author: dmills
author_rank: Super Contributor
timestamp: November 21, 2018, 11:13:05 am
content: An opamp, cap and resistor will get you a ramp, maybe use the micro to generate the reset pulse to discharge the integrator capacitors (Or go old school and do that with a 556!).Of course the nice thing about a DAC is that you can use lookup tables to produce non linear sweeps to correct for (some) issues in your electron optics, that right there might make it worthwhile.Regards, Dan.

author: Berni
author_rank: Super Contributor
timestamp: November 21, 2018, 11:20:54 am
content: You can look into CRT oscilloscope time base ramp generators. They are often built out of transistors and passives and can work at MHz rates.The downside of them is that while very simple they could be difficult to digitally set the speed over a wide range of ramp speeds. In oscilloscopes they use big rotary switches to swap the passives out as you select different timebases.Digital DAC methods do provide flexibility advantages where you can easily set the speed accurately over a very wide range of sweep rates. And yes being digital you can also use a lookup table to fix any potential linearity issues in the amplifiers or the electron deflection system. You can run a DAC at a few MHz sample rate using SPI and a MCU. Adding some anti aliasing filtering on top and you get your nice smooth ramp.

author: Marco
author_rank: Super Contributor
timestamp: November 21, 2018, 11:34:05 am
content: You could just use one of the low cost Analog Devices DDS ICs, or one of the many modules thereof.
Dedicated USB C power deivery to charge Li-Ion - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: November 23, 2021, 09:56:55 am
content: I'm looking for an inexpensive chip that will handle both smart (eg Apple) "USB-C power Delivery" or dumb (5V only) chargers at the input.3A out would be fine.The target Li-Ion/Li-Poly (4.2V) would be 7 to 12AH.I'm interested to know aboutA chip (am considering MAX77757)A good summary (PDF etc) of just the power delivery side of USB-C, [ something not too long hopefully...]That is, the USC-C background required to use chips like MAX77757. I have the USB.org PDF on power delivery and it is probably excess detail for this situation.Any subtle/non-obvious 'gotchas'This is all new to me, I've only used '4-wire' USB to date.Looked at TI and their solutions all appear to require an I2C bus to control things, wheras I'm looking for an all-in-one solution.

author: jwm_
author_rank: Frequent Contributor
timestamp: December 01, 2021, 01:24:24 am
content: you can buy little boards for a couple bucks that do nothing but ask for the most power they can from a USB-C port then pass it on. they are pretty useful. I have usb-pd-ized a lot of projects with them.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 01, 2021, 03:31:56 am
content: 4V at 3A would be 12W, well within the capabilities of 5V USB-C. No need to do USB-PD unless you want more power or want to use some advanced features like telling the other end to go into OTG mode. Easiest solution would be a buck charger with adjustable current limit and a microcontroller to read the pullup resistor value. The device side pulls down the two CC lines with 5.1k resistors (which tells the other end to start supplying power), then check the voltage to figure out the resistor value.https://community.infineon.com/t5/Knowledge-Base-Articles/Termination-Resistors-Required-for-the-USB-Type-C-Connector/ta-p/253544One thing USB-C missed is when using a USB-A (regular USB) to USB-C cable, how to easily tell the difference between USB 2.0 and 3.0. With micro USB 3.0 or USB-A 3.0, it's a simple matter of checking if the USB 3.0 ground is in fact connected to ground. Perhaps it might work to check voltage or impedance on the USB 3.0 data lines?If you want to detect a dedicated USB-A charger, an easy way is to pull up one data line with a 100k resistor, then have a 1M pulldown on the other data line along with a connection to the microcontroller to check the level. The most basic of dedicated chargers simply bridge the data lines which is easily detected by that circuit.
Defect battery? Voltage higher than rated - Page 1
Forum section: electronics / projects

author: Teun
author_rank: Regular Contributor
timestamp: June 11, 2020, 12:18:02 pm
content: Hi Guys,I have replaced a rechargable battery recently, which was rated 3.6V but gave 4.045V.http://www.farnell.com/datasheets/1695897.pdf?_ga=2.188866731.1823348601.1591876850-2138108918.1589272900&_gac=1.43556759.1591599898.CKzHx6Pt7tICFQkUGwod0boJ2wI know charged batteries give a little more but this seems very much to me.It came off the EERPOM module of a CNC press brake. Since the battery is probably at least 20 years old is this a more common phenomenon?Does anyone have a decent explanation for this?

author: ni.st
author_rank: Newbie
timestamp: June 11, 2020, 01:11:33 pm
content: This battery consists of 3 NiMH cells in series, the open circuit voltage can therefore be as high as 3*1.4V=4.2V.So it is most likely not defective. If you connect a 1 kOhm load, the voltage will probably drop significantly.

author: mikerj
author_rank: Super Contributor
timestamp: June 11, 2020, 03:47:03 pm
content: The datasheet you linked to shows the terminal voltage could be close to 4.5v at a charge rate of 0.3C, and starts at around 4.2v on the discharge curves. 1.25v is simply the nominal NiMh cell voltage, it varies significantly from fully charged to full discharged.This is the same as Li-ion cells being rated at 3.7v when they vary between ~3.0 to 4.2v depending on load and state of charge.

author: cliffyk
author_rank: Frequent Contributor
timestamp: June 11, 2020, 06:10:23 pm
content: This is the key behind Dewalt and others touting their20V(Max)Lithium-ion cordless tools, as being allegedly superior to the plain 'ol 18V tools such as Ryobi's. 5 * 4.2 (fully charged, which drops very rapidly under load) = 21 V ; 5 * 3.7 (nominal) = 18.5 V. Check a freshly charged "18 V" Ryobi battery and you'll see 20 V and a bit same as the other's "20 V" systems. It's just a typical marketing department white lie...

author: Teun
author_rank: Regular Contributor
timestamp: June 12, 2020, 11:13:31 am
content: Ah ok. I'm not really into battery technology.But it did measure 4.045V under load however.

author: tunk
author_rank: Super Contributor
timestamp: June 12, 2020, 12:14:08 pm
content: A guess is that the battery is used to store volatile datawhen your device is off, and that it is being charged whenit's on.

author: cliffyk
author_rank: Frequent Contributor
timestamp: June 12, 2020, 05:04:34 pm
content: Quote from: Teun on June 12, 2020, 11:13:31 amWhat was the magnitude of that load--must have been quite small...
define PWM input for step response.... - Page 1
Forum section: electronics / projects

author: ammjy
author_rank: Regular Contributor
timestamp: April 08, 2018, 12:41:43 am
content: Hello, EEVBlog Users ! Thanks you for click.i don't have idea how i can define PWM input for matlab system identification toolbox.i'm using matlab "system identification toolbox" for get transfer function of RC servo motor.i already get very nice step response result of RC servo with 1->2ms PWM signal.the problem is this..input signal is PWM 1->2ms signal.if, input signal is kind of voltage change like a 0 -> 5V. i can get transfer function directly.but this is PWM signal...can i use just PWM directly ? or i should convert PWM to some numbers ?

author: Nitrousoxide
author_rank: Regular Contributor
timestamp: April 09, 2018, 01:36:26 pm
content: Just an idea, perhaps you can convert the PWM signal to a control voltage by performing a low pass on the PWM. However, this will introduce a significant delay and attenuate any high-frequency changes, which may affect your input step signal.Ideally, you would record the control voltage before PWM modulation.

author: ammjy
author_rank: Regular Contributor
timestamp: April 09, 2018, 08:30:39 pm
content: Thanks you Nitrousoxide !!i already solved !Thanks you for your comment.in this case, i just use angle command.i mean..i gve 0.25 number for 1ms PWM.then i can use just 0.25 !Thanks you !
Deglob IC's - Page 1
Forum section: electronics / projects

author: lgbeno
author_rank: Frequent Contributor
timestamp: August 03, 2013, 08:17:57 pm
content: I've been curious about what it would take to etch away the plastic from some IC packages to reveal what's inside. I'm sure it involves toxic and dangerous chemicals but think that I could make a setup to do it safely.Has anyone on the forum done this before?What chemicals might be involved?Where can I get my hands on said chemicals?Anyone with pictures should post themSent from my iPhone using Tapatalk 2

author: edavid
author_rank: Super Contributor
timestamp: August 03, 2013, 08:34:20 pm
content: Here's a nice summary:http://www.semitracks.com/index.php/reference-material/failure-and-yield-analysis/package-analysis/delid-and-decapMore:http://www.google.com/search?q=decap+red+fuming

author: EpicIntelGamer
author_rank: Regular Contributor
timestamp: August 03, 2013, 09:34:13 pm
content: Ben Krasnow on youtube has done just this and made a video about it.Here you go:
Delay a signal by a clock, or 2, or 3 - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: February 12, 2018, 01:56:42 pm
content: I am thinking of messing around with connecting a Z80 to an AVR and using the AVR for the I/O. A few people have done this using a 7474 flop flop to trigger the WAIT signal on the Z80 so the AVR can keep up. On an OUT instruction from the Z80 this should be simple, AVR captures data pins and clears the flip flop to allow the Z80 to continue, but an IN instruction requires the AVR to put data on the bus, release the WAIT, but then it also has to get off the bus before someone else needs to use it.This assumes that the Z80 and AVR and clocked synchronously...Pseudocode for it might be:isr_for_IN_to_Z80(){PORTx=data;DDRx=0xff;set_pin_to_clear_flipflopDDRxX=0x00;clear_pin_to_clear_flip_flop}So my question is, if the time between set_pin_to_clear_flipflop and the next instruction to set the port to input is too long (and I don't know if it is or isn't), what type of logic device would you use to delay the set_pin_to_clear_flop? Something that could delay by 1, 2, 3, clocks, etc.

author: JVR
author_rank: Regular Contributor
timestamp: February 12, 2018, 04:20:31 pm
content: Simplest would be a decade counter, or a chain of flipflops.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: February 12, 2018, 05:38:59 pm
content: A serial in parallel out shift register, feed the signal into serial in, connect the clock, and tap it delayed at the parallel out pins, bit #n -> n clocks delayed.
Delayed “hold on” circuit ideas? - Page 1
Forum section: electronics / projects

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: March 27, 2022, 04:57:29 pm
content: I’m suffering from brain fog, I’ve built one of these in the past but can’t quite sort a simple solution.The circuit is to hold a data radio transmitter on transmit for 15 to 20 mS after the keying line drops. The transmit duration can be anywhere from around 100 mS to 20 or 30 seconds. The key line is normally high, and pulled low to transmit.Your thoughts are appreciated.SJ

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: April 05, 2022, 12:21:39 pm
content: I finally found the original board that I used in 2008. I have drawn the circuit and attach it here.
Dell 12v54A Server PSU for a car amp. - Page 1
Forum section: electronics / projects

author: phaseform
author_rank: Regular Contributor
timestamp: August 07, 2016, 03:08:17 am
content: Readingthisthread it's mentioned that server PSU's aren't designed for fast current transients, I'm wondering if this could be overcome by putting caps between the PSU and a 12v car amp. I'm wondering as to a good source for high current, high capacity caps, as the ones I've seen for car amps appear to be largely marketing and not living up to specs.

author: ConKbot
author_rank: Super Contributor
timestamp: August 07, 2016, 06:24:29 am
content: CPUs have their own converters between the 12v psu and the processor, but then, so will a car amplifier. Keep the wiring beefy, short, close together to minimize inductance. As long as you're not expecting transients higher than the power supply output, it should be ok.You really need a lot of capacitance to provide any sort of surge capability. 5x 310F supercaps in series (62F total, $60ish worth if you get new Maxwell ones from mouser) would provide an extra 360W of surge capability for 1 second if of the voltage dips from 12.0 to 11.5V. A 1F cap can provide 6W for 1 second with the same half volt dip.So unless the car amp is lacking in input and output filtering on the internal power supply, a real possibility on cheap ones, and your long power cables have a lot of inductance (long runs in a car) a 1F electrolytic (even if it wasn't a cement filled fake) won't help with transient response/short bass hits for a subwoofer amp.Edit: not suggesting actually using the super caps, just making an example. If you did, you'd need balancing resistors, and a startup/charging circuit to keep it from overloading the power supply when you turn it on.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 07, 2016, 05:59:42 pm
content: Quote from: blueskull on August 07, 2016, 03:15:48 amAnd automotive power systems are very noisy to begin with. If the amp is half decent, it will have plenty of filtering.
Dell L1100E-S1 Server PSU - Page 1
Forum section: electronics / projects

author: nagz
author_rank: Contributor
timestamp: July 23, 2025, 11:10:40 pm
content: Hi,I'm looking to connect several Dell L1100E-S1 server power supplies together to get various DC V and current outputs.Has anyone done this with this model or has a product/technical manual they can send my way so i can reference connections and any load sharing details?Cheers,Nagz

author: jwet
author_rank: Frequent Contributor
timestamp: July 24, 2025, 03:26:47 pm
content: These big power supplies are often used by Ham Radio guys for powering their shacks or big solid state power amps. Its common enough that you can just google:using server power supplies for amateur radioYou'll find plenty of videos and blogs that should give you some guidance. These things are an amazingly cost effective solution and hams are generally cheapskates!

author: tunk
author_rank: Super Contributor
timestamp: July 24, 2025, 05:30:59 pm
content: Seem to remember that zero volts is connected to the casing, which again is connected to ground/earth.If that's the case, you will have a problem if you connect them in series.

author: nagz
author_rank: Contributor
timestamp: July 25, 2025, 03:14:30 am
content: This is trueI’ve just order a bunch of nylon screws and washers to separate everything

author: coromonadalix
author_rank: Super Contributor
timestamp: July 25, 2025, 02:53:53 pm
content: you may find infos on RCGROUP ....

author: shabaz
author_rank: Frequent Contributor
timestamp: July 26, 2025, 12:15:21 am
content: I was recently given a similar PSU by a friend, although it is a HP one, not Dell. The schematic I'm using is attached, but no guarantees it will work. I'm not combining PSUs though.I have got my PCBs made, but I'm struggling with the mechanical side of things, since these PSUs are intended for sliding into servers, and of course I don't have such a chassis. I did see a 3D printed chassis idea online somwhere, but I was hoping to try something else, since it needs to be fairly rugged and ideally non-flammable! Anyway, it's not a solved problem for me, so this is currently on hold, but I might get back to it in a couple of months time. Another thing, is after all the time and effort, I wonder if it may be cheaper to buy a ready-made supply.
Dell laptop power adapter disassembly question - Page 1
Forum section: electronics / projects

author: FlashEF
author_rank: Contributor
timestamp: January 15, 2013, 03:44:06 pm
content: I am trying to do a simple power cord replacement in a DELL laptop power supply. The cable got damaged just next to the plug. I was able to find a replacement part - entire new cable for just a few euro. The problem is how to open the power supply not damaging the case. Model number is DA130PE1-00. It looks like this:My searches for a service manual/disassembly guide gave no effect. It seems that this thing may be designed not to be repaired.Any tips on how I could attempt to open this thing? Worst case I'll just cut the cable and attach the new one to the old one.

author: krivx
author_rank: Frequent Contributor
timestamp: January 15, 2013, 03:49:03 pm
content: This was discussed recently but I can't remember the thread title. I like to crack open these kind of cases in a vice, here's an example

author: firewalker
author_rank: Super Contributor
timestamp: January 15, 2013, 03:55:50 pm
content: The thread is the one bellow. If I remember correctly a Dell laptop PSU I had dismantled was heavily potted. It was PITA.https://www.eevblog.com/forum/beginners/how-do-you-break-open-wall-warts-and-brick-type-psus/Alexander.

author: tld
author_rank: Regular Contributor
timestamp: January 15, 2013, 05:21:15 pm
content: Quote from: firewalker on January 15, 2013, 03:55:50 pmWhy not just cut both the old and the new cable?Of the cable connected to the brick, leave about half of it. Of the replacement cable, leave the laptop-facing end, join the two, heatshrink the joint?Seems both easier and safer?tld

author: FlashEF
author_rank: Contributor
timestamp: January 15, 2013, 05:31:09 pm
content: Quote from: tld on January 15, 2013, 05:21:15 pmIt seems like the best option now. I thought it would be better to ask first to see if there may be a solution I don't know about. They sell those cables with strain relief plastic part that fits in to the casing. Seemed logical that you can replace the thing in a "cultural" way.Love it when "disassembly guide" means "selecting the right hammer"Anyway, thanks for advice everyone

author: firewalker
author_rank: Super Contributor
timestamp: January 15, 2013, 09:17:02 pm
content: Quote from: tld on January 15, 2013, 05:21:15 pmPersonally speaking I didn't want to change the cable. Just wanted to take it apart. The identification chip(DS2501) was blown and someone through it away.Alexander.