hybridfree/eevblog-posts huggingface dataset:
Low side relay switching overvoltage protection - Page 1
Forum section: electronics / projects

author: golf32
author_rank: Regular Contributor
timestamp: February 22, 2023, 07:37:47 pm
content: I have a circuit where I need to switch an external relay via an optocoupler. It would be really convenient if I only had to connect relay low and ground as shown in the schematic:In this case the relay would have +24V from another source and the opto would open the low side path.If this were the case, I wouldn't have access to the high side of the relay to put a flyback diode. I know many relays (particularly the DIN mount relays which I am targeting) have internal flyback diodes, but I want to ensure you can never damage the opto.The first thing that comes to mind is adding a zener diode across the collector and emitter of the transistor. However, in my simulations, the current is much higher than the typical flyback configuration. I've also never seen this configuration before, and a cursory google search has come up empty handed on other techniques.Any advice? Thanks in advance.

author: SeanB
author_rank: Super Contributor
timestamp: February 22, 2023, 08:20:37 pm
content: Zener diode will work, but better is a transorb or MOV, rating determined by the breakdown voltage of your open collector output, not the relay supply voltage. Placed across the transistor collector to emitter to clamp the maximum voltage there to under the maximum for the transistor, and od course it should be well above the supply voltage. Typically your transistor will be rated for 100V or more, so a clamp of around 48V will work fine.

author: golf32
author_rank: Regular Contributor
timestamp: February 22, 2023, 08:31:07 pm
content: Quote from: SeanB on February 22, 2023, 08:20:37 pmOf course, a MOV makes total sense. Thanks, I think that answers my question.

author: Benta
author_rank: Super Contributor
timestamp: February 22, 2023, 10:26:15 pm
content: SeanB's reasoning is sound, and the choice of 2x relay coil voltage as well. That will reduce contact arcing/burn.Whether you choose a MOV or a TVS is not really important.
Low size and Cheap Half bridge mosft driver - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: December 16, 2017, 07:38:51 am
content: Hi,I wanted to build my Speed controller for my quad, I wanted to know if you happen to know some small sized and reasonabley priced ones in mind, something with the Highside voltage of more than 25V and capable of more than 600ma would be nice, I want something at least half the size of a soic8 package.Any hints?

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: December 16, 2017, 08:35:12 am
content: Thanks
Low-Temp Drift Instrumentation Caps - Page 1
Forum section: electronics / projects

author: AndyFroncioni
author_rank: Contributor
timestamp: June 15, 2011, 11:22:08 am
content: I know nothing about capacitors. As I'm discovering, though, not many people do.I am in need of a low-temperature drift pair of RC elements to put into an 822-based follower circuit for a sensor. The RC time-constant should be in the range of 0.05s to 1.0s I would like surface-mount components. Temp range: 0C to 70C.Can someone please offer a quick tutorial and/or possible suppliers of intrumentation-grade caps?

author: ejeffrey
author_rank: Super Contributor
timestamp: June 15, 2011, 01:19:09 pm
content: Polyester film caps and low-k (C0G NP0) ceramics are the go-to caps for anything in an analog path. For such low frequencies, film caps are probably where you have to look. You may find surface mount varieties, but they are much more commonly leaded components due to their physically large size.For 1 second and above I would begin to consider using an active circuit with a capacitance multiplier circuit to keep the R and C values manageable.

author: tekfan
author_rank: Frequent Contributor
timestamp: June 15, 2011, 01:26:55 pm
content: As far as I know silvered mica capacitors are used in high precision test equipment. They have very low temperature coefficients and low tolerances. But are quite expensive.

author: ejeffrey
author_rank: Super Contributor
timestamp: June 15, 2011, 08:27:46 pm
content: Also very small values which is why I didn't mention them. They are usually only used at RF, where their low inductance and dielectric losses are important.

author: AndyFroncioni
author_rank: Contributor
timestamp: June 15, 2011, 10:05:14 pm
content: Quote from: ejeffrey on June 15, 2011, 08:27:46 pmWould you know of any suppliers of such caps? Can I find them on DigiKey? How would I find them? (It's not as easy as it seems.)

author: ejeffrey
author_rank: Super Contributor
timestamp: June 16, 2011, 07:27:52 am
content: Just search for capacitor on digikey. You will see options for "ceramic" (both high-K and low-K are here), film (includes both polyester and polypropylene), and "Mica and PTFE (teflon)".

author: AndyFroncioni
author_rank: Contributor
timestamp: June 16, 2011, 01:30:30 pm
content: Quote from: ejeffrey on June 16, 2011, 07:27:52 amThanks so much. As simple as this may seem to you, it's very valuable information for me.Cheers!Andy
low voltage controlled high voltage - Page 1
Forum section: electronics / projects

author: sdouble
author_rank: Frequent Contributor
timestamp: July 27, 2015, 07:51:50 pm
content: hi guys,I have a question for you.Here is my trouble.I have a charge integrator with a FET input.I have a AC coupling to the sensor since I bias it to about 500 V.In the current design, if an idiot (could be me) turn on the high voltage without low viltage to bias the FET... boom.The FET dies.Therefore, I would like to condition the HV to the presence of the Low voltage on the FET drain (about +3 Volts).Any idea on you side on how to do that ?CheersJulien

author: mmagin
author_rank: Frequent Contributor
timestamp: July 27, 2015, 10:41:23 pm
content: If you shorted the fet input, would that cause any harm? If no to both questions, consider shorting the input to the fet with a normally-closed relay with a coil that runs off the low voltage supply.Alternately, can you just prevent the high voltage from going on until the low voltage is on? If it's a line voltage powered high voltage supply, maybe just use an ordinary relay (or SSR) to switch it on and off. If you need to switch the high voltage itself, it looks like you're looking at fancy reed relays ($30+).
Low voltage cutoff suitable for power tool batteries. - Page 1
Forum section: electronics / projects

author: Hugoagogo
author_rank: Newbie
timestamp: April 08, 2018, 12:26:54 am
content: I have a number of projects on the go, nearing completion that I plan to make use of the various Milwaukee M18 battery packs that I own for use with cordless drills etc. To be clear these project only use power from the batteries and do not charge them.In these packs the cell terminals are directly exposed through the battery connector, without any battery protection or low voltage cutoff. The tools that connect to these cells tend to come in two varieties, low power tools that only have two contacts, and do their own low voltage cutoff (lights, radios, usb adapters), and high power tools (drills, blowers, saws) that use 4 pins, two of which are some kind of communications, which tells the controller in the tool when to shut off.For the first part of my question, has anybody had a go at reverse engineering these comms and using them to tell their own projects to shut off.Secondly I have been working on designing a low voltage cutoff circuit that cuts out at 17.5V, and can pass up to 20A. When having a go simulating most of the circuits around on RC car forums or stack exchange, most of them draw a fair amount of current when off and/or lack hysteresis meaning that due to source impedance the tend to oscillate due to the voltage rising again when the load is removed.I found the ATL431 which seems to be a far superior replacement to the TLV431, plus that adding a bit of hysteresis to the voltage divider and additional gate capacitance to the mosfet greatly tidied up the result when simulating the circuit.However li-po batteries deserve some respect, especially when they don't have proper cell protection. Can anybody see any issues with the attached circuit. The source in the schematic is set up with a 100mohm impedance.

author: Hugoagogo
author_rank: Newbie
timestamp: April 08, 2018, 12:41:37 pm
content: I did a little additional mucking about and found that if the voltage drops off too slowly the current will not shut off quick enough, and will just kind of linearly ramp down to zero.A bit more messing around and I changed the circuit to provide a cutoff until the battery is removed. This also provides much faster switch off and prevents oscillation.See attached.

author: shasse
author_rank: Newbie
timestamp: January 27, 2021, 12:03:04 am
content: I'm considering a similar project with M18 batteries and I was wondering how this worked out for you.Thanks!Scott
Low voltage isolation question - Page 1
Forum section: electronics / projects

author: c4757p
author_rank: Super Contributor
timestamp: July 11, 2013, 07:01:47 pm
content: I need to isolate a small, low-power section of a circuit against a DC bias. This isn't a safety isolation - it only needs to stand off 40V maximum, DC only. Because the circuit section is a pretty small piece of a pretty complicated whole, I'd like to keep the power supply for it small as well. Since I don't need safety isolation, would it be reasonable to use a pair of capacitors to couple power, as shown in the attachment? (I intend to use a third to couple the signal back.) I'll also put a reasonably beefy TVS diode across C3 to dissipate static charge.Can anybody see any problems with this that I am missing? Also, any ideas to make it work with an AC bias as well? If I remove C3 and add AC to the bias voltage, obviously that AC ends up being rectified and added to the coupled-in power.

author: cosmos
author_rank: Regular Contributor
timestamp: July 11, 2013, 08:12:30 pm
content: I think that should work nicely.I have done a similar circuit recently (charging a NMOS gate to near 10V with a two stage chargepump like this, pumped with 5V @ ~100Khz)no C3 and the DC offset was a battery but could be moving fast with large loads.We aimed at low power so it had much higher impedances and smaller capacitances => slow.If there is a problem we have not seen it yet
Low voltage soldering iron necessary in oscilloscopes? - Page 1
Forum section: electronics / projects

author: moonpie
author_rank: Newbie
timestamp: December 28, 2013, 09:42:03 pm
content: Hi allI have an old analog Philips PM3214 2-channel oscilloscope that needs soldering.It is the first resistor just after the input BNC connector on one of the channels that is loose and needs to be soldered.The scope has a double insulated transformer and is NOT grounded to mains earth.The service manual (for similar model PM3217) says: "When you are soldering inside the instrument it is essential to use a low-voltage soldering iron, the tip of which must be earthed to the mass of the oscilloscope."Will I be OK if I ground the case of the scope, and then use my 220V iron on it? The tip of my 220V 15/30W iron is grounded.What are the dangers of not using a low voltage iron? Static electricity?moonpie(An electronics newbie)

author: oldway
author_rank: Super Contributor
timestamp: December 28, 2013, 09:52:01 pm
content: First select the ampl/div switch of the channel on 10V/div before soldering, and there is no risk of damage any more.

author: c4757p
author_rank: Super Contributor
timestamp: December 28, 2013, 09:52:15 pm
content: Quote from: moonpie on December 28, 2013, 09:42:03 pmYou're fine.

author: nanofrog
author_rank: Super Contributor
timestamp: December 28, 2013, 10:04:40 pm
content: Quote from: c4757p on December 28, 2013, 09:52:15 pm+1

author: Nerull
author_rank: Frequent Contributor
timestamp: December 28, 2013, 10:33:17 pm
content: Some - mostly older - irons have voltage from the heating element exposed on the tip from leakage, which can damage sensitive components. If your tip is grounded, you should be fine.My old ratshack firestarter didn't even have a grounding plug.

author: oldway
author_rank: Super Contributor
timestamp: December 28, 2013, 10:37:34 pm
content: Do'nt trust this too much.My computer is grounded but when I touched the case, I felt an electric shock.I asked an electrician to check this and he found that the ground of the main plug was not conected.

author: Nerull
author_rank: Frequent Contributor
timestamp: December 28, 2013, 10:38:46 pm
content: In that case your computer was not grounded.Nothing will be properly grounded if your mains ground connection is faulty.

author: oldway
author_rank: Super Contributor
timestamp: December 28, 2013, 10:44:20 pm
content: It was "apparently" grounded...nobody check if this is really the case.With the ampl/div switch of the channel on 10V/div before soldering, there is no risk at all, correctly grounded or not.

author: moonpie
author_rank: Newbie
timestamp: December 29, 2013, 03:48:03 pm
content: Thanks for all the input. I will not worry too much then.

author: KJDS
author_rank: Super Contributor
timestamp: December 29, 2013, 04:20:40 pm
content: If in doubt, touch the tip of the iron to the case of the scope before anything else. If it sparks, use a different iron.
Low Vout, high Iout SMPS like on motherboards - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: July 31, 2019, 09:38:05 am
content: In "The Art of Electronics" III, p637 is a footnote (see attached) saying microprocessors can need 1V at 60A.Wow! That does surprise me.I'd be interested to see a datasheet for one of these things. I tried looking for part numbers of those chips, so far not found one.

author: MagicSmoker
author_rank: Super Contributor
timestamp: July 31, 2019, 09:49:28 am
content: The search phrase you want to use is "multiphase buck converter" (or polyphase). This can be done with regular controller ICs that have a way to sync the clock then syncing each one to a phase-shifted clock, but motherboards will invariably use a special purpose IC capable of 2-8 phase operation.

author: TiN
author_rank: Super Contributor
timestamp: July 31, 2019, 11:10:14 am
content: That is quite outdated already, modern CPUs/GPUs can eat up over 400-500 Amp already with voltages in range 0.7 - 1.1 VDC.Typical high-end GPU have 10+ phases DC/DC, with integrated 80A rated power stages (contain low-side/high-side FET and driver in one package), digitally adjusted VRM controllers, etc.One such example, next to last-year high-end GPU card.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 31, 2019, 06:49:59 pm
content: Figure basically the whole thing runs at ~1V. Any time you see TDP (total dissipated power), figure about as many amperes!Hm, are the IO pins ran from 1V as well or something else (1.5, 1.8, 2.5)? Back in the day I know the SSTL stuff was higher voltages, but I don't think that applies anymore, either...Tim

author: ejeffrey
author_rank: Super Contributor
timestamp: July 31, 2019, 11:18:41 pm
content: I know there are already systems out there that deliver high voltage to the package and use SMPS in the package because delivering 300A at 1 volt through a BGA gets really annoying.

author: TiN
author_rank: Super Contributor
timestamp: July 31, 2019, 11:55:04 pm
content: I/O usually runs at 3.3V, and 1.8V for more modern cards. There are other I/O voltages and termination voltages too for stuff like PCIe/SerDes XVRs, etc.
lower noise AC regulation circuit variants - Page 1
Forum section: electronics / projects

author: enterio
author_rank: Newbie
timestamp: July 08, 2023, 10:04:49 pm
content: Hi electrotechnicians, new here and new quite new to ele too....so bear with me, pleasebottom line: I want and advice to which type of circuit to pick to be able to pass EMC testing more easily...than the other alternative.circuit purpose: to control resistive load power. load nominal operational voltage is 220VAC and it's 200W thing. A heater.the two alternatives I have (or have come up with) are:a)diac controlled triac. Opto-diac is being controlled by microcontroler (arduino) which is sensing the AC phase, so it basically knows when will triac trurn off and it is turning the diac on to turn the triac on based on program/preference of such phase shift.schema I found online:b)PWM controlled MOSFET on the low side that open-closes rapidly and controls the effective voltage (rectified) on the load that way:please, assume some similar conditions for both circuits: the same load, the same mains, 2 layered PCB and some wires to the load...some reasonable conditions that are real enough and we can work this thought experiment out with.hope it's enough for the starter,thanks

author: CosteC
author_rank: Regular Contributor
timestamp: July 10, 2023, 07:00:49 pm
content: Group control will give you lowest noise IMHO. 200 W heater shall not notice your "long" on/off cycles.

author: Roehrenonkel
author_rank: Frequent Contributor
timestamp: July 10, 2023, 07:15:02 pm
content: Hi,Quote from: CosteC on July 10, 2023, 07:00:49 pm....never heard of that therm "Group-control". But i guess it's similar to the german "Impulspaket-Steuerung".Combined with a SolidStateRelay with zero-crossing-switching one should be good for the emc-test.Good luck

author: Benta
author_rank: Super Contributor
timestamp: July 10, 2023, 07:32:57 pm
content: English: burst control.Basically PWM at a much lower frequency than 50/60 Hz. With zero-crossing SSRs it's practrically noiseless (EMI-wise).

author: CosteC
author_rank: Regular Contributor
timestamp: July 10, 2023, 07:34:07 pm
content: Yes. You switch only at zero crossings -> low noise, easy for implementation. Some people will tell you resolution is poor, which is nonsense for 200 W heater - for such heater 10 ms "packets" of heat are very small.

author: Marco
author_rank: Super Contributor
timestamp: July 10, 2023, 08:33:34 pm
content: Quote from: Benta on July 10, 2023, 07:32:57 pmIdeally more like pulse skipping in a DC DC converter. You can approach it like PWM, but that's how you end up with all those shit induction cookers.
Lowering noise and Zo of LM317 - Page 1
Forum section: electronics / projects

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: October 05, 2022, 04:11:11 am
content: I was looking low noise regulator for low level signal treatment, I gave a chance to LM317 if can lower its noise. I simulated for 100ma 15v output, here what I came about.Do you think this is real?The first two graphs are with R3 and C1 =0

author: magic
author_rank: Super Contributor
timestamp: October 05, 2022, 05:08:27 am
content: Not sure what simulator you are using, but in LTspice I can plot noise contribution of individual components. If you can plot R1+R2+R3, you will probably see it's equal to the total simulated noise.1kΩ generates 4nV/rtHz Johnson noise, this circuit has gain of 11x. Your result is in line with what I would expect from resistors alone, even a little less, not sure what's wrong with my expectations (or with the simulator).At any rate, I don't think your LM317 model includes noise. A noise plot might be available in the datasheet, or you may look for measurements done by others, they surely exist out there. IIRC it was over 100nV/rtHz for LM317, but I may be wrong.editBuild it and see if it's too noisy for the application, then worryI don't know if output impedance is correct in your model, but an improvement is expected in this circuit because the LM317 runs at unity gain at "medium" frequencies. If you expand the plot down to DC, you will notice that nothing changes, it always gets worse with increasing output voltage.

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: October 05, 2022, 06:38:28 am
content: I think the noise of LM317 is not implemented in simulation, its the resistors noise only which is getting reduced.

author: Avelino Sampaio
author_rank: Frequent Contributor
timestamp: October 05, 2022, 08:47:40 am
content: Lots of info in this thread below:https://www.diyaudio.com/community/threads/d-noizator-a-magic-active-noise-canceller-to-retrofit-upgrade-any-317-based-v-reg.331491/

author: tooki
author_rank: Super Contributor
timestamp: October 05, 2022, 08:54:32 am
content: Why not just use a lower-noise regulator to begin with?

author: Terry Bites
author_rank: Super Contributor
timestamp: October 05, 2022, 12:55:04 pm
content: The plots are from this article by Steve Hageman,www.edn.com/simple-circuits-reduce-regulator-noise-floor, yes?I'm sure it's bona fide. It looks like you can get an order of magnitude of improvement. Worth having.It looks like these plots are from the TINA-TI simulator.The Zo of the regulator is lowered by the action of the feedback loop. Component values have already been optimised by the manufacturer.

author: Vovk_Z
author_rank: Super Contributor
timestamp: October 06, 2022, 11:20:45 am
content: I still don't get noise plots from the first post. Does it mean TS has kind of almost 0 nV/sqr(Hz) at 1 kHz noise? That's impossible.Does TS have a true-RMS microvoltmerer (or at least a millivoltmeter) to make some real noise measurements?
Lowering DC voltage without using a voltage divider - Page 1
Forum section: electronics / projects

author: IN0RAN
author_rank: Newbie
timestamp: February 01, 2016, 05:59:19 pm
content: Hey guys! I have project where I have to measure voltage from a 40VDC (max) source using an acquisition device that has an input limit of 5V. So far, the only viable solution I've come up with is the attached image, a voltage divider and a buffer for isolation. ButI want to know if there's any other solution that I can build(so, no DC-to-DC converters).Thank you in advancePS: I know this is a good and easy solution, but I'd like to know the alternatives, if there's any. It's just me being stubborn for the sake of learning

author: KJDS
author_rank: Super Contributor
timestamp: February 01, 2016, 06:27:17 pm
content: http://www.eetimes.com/document.asp?doc_id=1272269

author: Supercharged
author_rank: Regular Contributor
timestamp: February 01, 2016, 06:36:41 pm
content: If you need a high impedance input try this (see picture). Its a basic design but it'll do the job. (sorry for the crude drawing)

author: max_torque
author_rank: Super Contributor
timestamp: February 01, 2016, 06:59:00 pm
content: Quote from: Supercharged on February 01, 2016, 06:36:41 pmWon't the op amp power rails have to include(exceed) the 40v measurement potential??

author: Supercharged
author_rank: Regular Contributor
timestamp: February 01, 2016, 07:08:32 pm
content: Quote from: max_torque on February 01, 2016, 06:59:00 pmYes but you can use two seperate power rails for the ADC and for the Opamps.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 01, 2016, 07:16:26 pm
content: The circuit should also have some extra compensation for the upper OP. Just standard OPs might very well start to oscillate, as the upper OP sees extra amplification inside the feedback loop. So use something like a resistor at the output of the lower OP and a capacitor in feedback at the upper OP.

author: Supercharged
author_rank: Regular Contributor
timestamp: February 01, 2016, 07:27:30 pm
content: Quote from: Kleinstein on February 01, 2016, 07:16:26 pmI agree, my design is just a basic concept and should be tested and improved.

author: IN0RAN
author_rank: Newbie
timestamp: February 02, 2016, 03:36:27 am
content: Quote from: KJDS on February 01, 2016, 06:27:17 pmThank you for this, I wasn't aware of the errors associated with measurements that used a voltage divider.
Lowest offgassing commodity PCB material for heating elements? - Page 1
Forum section: electronics / projects

author: incf
author_rank: Frequent Contributor
timestamp: April 15, 2025, 02:26:29 am
content: Do any commodity/cheap PCB materials exist that outgas significantly less than others when used as a heating element?Flex PCB material (which is Polyimide I think) comes to mind. But I don't know for sure. Maybe somebody here would know.edit: max temperature: 100C/212F

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: April 15, 2025, 03:08:16 am
content: You might find something here-https://www.rogerscorp.com/advanced-electronics-solutions/rt-duroid-laminatesProbably not cheap and you don't want to be using PCB as a heater at particularly high temperatures.
LPC4370 cheap scope: 80Ms/s 12 bit LPC LINK2? £14 from Mouser. - Page 1
Forum section: electronics / projects

author: DAIRVINE
author_rank: Contributor
timestamp: February 04, 2015, 10:32:18 am
content: 80MHz 12 bit ADC processor LPC4370.LPCxpresso do a LPC LINK2 and LABTOOLS open source oscilloscope demo set. (£84 from Mouser, seems quite well liked.)The LPC LINK2 is £14 + VAT from Mouser, it has the ADC on board. The Lab tools board has signal conditioning, BNC, protection etc.Using just the LPCLINK2 board:Remove C14. Add a 27K resistor between the old C14 input pin and pin 2 of J4 (VDDA +3.3V). Replace R3 with a range set resistor, for example 100k for about +-10V input. (gives 5mV resolution.) The open circuit input will float up slightly. The input impedance of the ADC is specified as 5k in parallel with 4.5pF. Bandwidth will be around 10MHz.Connect input to J4 pin 6 and a GND to pin 1.There are a number of possible variants which may perform better or be easier to do or provide additional channels.The open source software would have to be hacked as various peripherals on the lab tools board are missing.I have not tried this proposed mod.

author: DAIRVINE
author_rank: Contributor
timestamp: February 05, 2015, 12:41:08 pm
content: Reviewhttp://www.drdobbs.com/embedded-systems/embedded-tools/240168337Datasheethttp://www.nxp.com/documents/data_sheet/LPC4370.pdfhttp://www.lpcware.com/lpclink2http://www.embeddedartists.com/products/app/labtool.phpSource firmware and app:https://github.com/embeddedartists/labtoolRelevant linkshttps://groups.google.com/forum/#!topic/labtool/Rtp3ZCPygfU
LPC812 PID Controller - Page 1
Forum section: electronics / projects

author: mubes
author_rank: Regular Contributor
timestamp: January 19, 2014, 11:37:58 pm
content: Folks,I just completed a PID controller based on the NXP LPC812 in C. The code should easily transition to other platforms but, at a quid a piece, the 812 is quite a reasonable choice anyway. It uses a MAX6675 thermocouple interface to a K-type thermocouple and its initially been applied to reflow soldering (firing a solid state relay). User interface is over a serial link, but adding switches and LEDs would be trivial. The easiest board to get started with would be a LPCXpresso 812 although I've also done my own circuit which should be available in a week or two when the new PCBs come back and have been validated.The code is available athttps://github.com/mubes/leater/and there's some background documentation available athttp://www.marples.net/Leater. Feel free to ask questions or kickoff discussions on this thread. The project remains open to be extended so suggestions are welcome, I'd particularly value some help/advice/input on strengthening the PID itself as it's a new area to me and there are people here who I can learn a lot from. It delivers a reasonably good Reflow Oven profile, but I'm not convinced it'll be stable for other applications yet....just in case it's useful to someone.DAVE
LPDDR3 decoupling caps - on every power pin? - Page 1
Forum section: electronics / projects

author: deanclaxton
author_rank: Regular Contributor
timestamp: December 07, 2022, 09:52:33 am
content: I'm working on a design atm that includes 1GB LPDDR3 - the first time I've designed something like this. The datasheets dont seem to go into any detail on decoupling - I checked a few different manufacturers datasheets.I've seen some designs where every power pin is decoupled, but is that overkill given the close proximity of the pins to one another? I wonder if they can be decoupled in groups of pins if some care is taken to minimise loop area.I guess ultimately individual caps would be the way to go - wondering what approach is taken by others who have designed with LPDDR3.

author: RoGeorge
author_rank: Super Contributor
timestamp: December 07, 2022, 10:21:52 am
content: Quote from: deanclaxton on December 07, 2022, 09:52:33 amIt depends. Do you feel lucky?Search for reference PCB designs, or for application notes from the memory chip manufacturers.Might work with less decoupling in a one shot prototype, but how do you test it will still work when random end user turns on some noisy LED light bulb, or when some WiFi router is nearby, and so on, over all the range of temps/humidity/vibrations/whatever?How much cost can be shaved off from RAM decoupling? Is it worth it?
LPDDR4/LPDDR4x Confusion - Page 1
Forum section: electronics / projects

author: palpurul
author_rank: Regular Contributor
timestamp: February 17, 2025, 09:02:28 pm
content: Hello everyone!I have been working on an FPGA board with (we think it's an) LPDDR4x RAM board and we recently discovered something that's a bit wierd.We have the evaluation kit for the FPGA and we assumed it had an LPDDR4x RAM on it because the RTL is set LPDDR4x configuration and the RAM's VDDQ supply is set to 0.6V (it should be 1.1V for the non-x LPDDR4).This is the part we have on the board:When I decode the part it shows up as an LPDDR4 RAM and it leads to this part:MT53E256M32D2DS-046 AAT:Bwhich is an LPDDR4 RAM.However, the VDDQ is set to 0.6V and RTL only works when we set the IP to LPDDRx.Are LPDDR4 and LPDDR4x can be used interchangebly by just changing the voltage?Thanks in advance!

author: bigendian
author_rank: Regular Contributor
timestamp: February 18, 2025, 01:50:51 pm
content: Issue is Micron specification, output from the decoding, they say lpddr4, while it is lpddr4x (2133 Mhz is lpddr4x), x is mainly an overclocking sign.
LPKF Promat c60 help - Page 1
Forum section: electronics / projects

author: cfcorp
author_rank: Newbie
timestamp: March 13, 2018, 10:04:57 am
content: Hi guys,I've got an LPKF Protomat c60 here and I was changing the bit but the collet/tool holder came out too.Does anyone know how its supposed to go back in. Ive lined the keyway up with the key on the spindle but it seems tight and I dont want to mess arounf with it.Anyone know how to resolve this? The manual doesn't specify how this can be resolved.Thanks

author: trevwhite
author_rank: Frequent Contributor
timestamp: March 13, 2018, 09:15:05 pm
content: Maybe LPKF themselves can help if you email them?
(db25) LPT port to stepper CNC  - Page 1
Forum section: electronics / projects

author: ijchan223
author_rank: Contributor
timestamp: March 07, 2015, 04:13:48 am
content: Hi guys, i just started trying to interface an old MaxNC 10 SRV CNC machine with a windows pc. Because the machine is so old, the company only offer software to drive the machine with DOS. So i thought i would quickly throw together a board that will make it work with Mach3. My Idea is to make a simple PCB that feeds signals in to some A4988 stepper motor drivers. Here is my current design, can you guys give me some feedback on what improvements I need to make.Stepper motor Drivers >>>https://www.pololu.com/product/1182

author: ijchan223
author_rank: Contributor
timestamp: March 08, 2015, 04:14:06 am
content: Changed my mind instead of making the adapter to convert the parallel port to the drivers, i purchased a breakout board that is isolated already. I will just attach the outputs to each driver with screw terminals since its not high current or anything .http://www.ebay.com/itm/231314366776?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

author: ijchan223
author_rank: Contributor
timestamp: March 08, 2015, 04:24:19 am
content: Below i have attached a photo of the idea i have in mind.
LQFP on PCB. - Page 1
Forum section: electronics / projects

author: luiHS
author_rank: Frequent Contributor
timestamp: November 03, 2020, 02:46:03 am
content: Hi.I design and manufacture my own boards, I have my own Pick and Place Neoden4.The problem I find is with LQFP chips, I use Kinetis MK66 LQFP144. The problem is how often there are pins of the chip that do not solder, it is as if all the pins are not perfectly aligned, and that causes some pins not to touch the pad of the PCB, sometimes even a strip of pins remain untouched with the pads on the PCB.In the end I have to put the boards under the microscope and manually solder all the pins that are not touching pin with pad on the PCB.I don't know if the solution is to configure the Pick and Place so that it presses the chip more against the PCB, and in this way it can compensate for the pins that are not at the same height. Or if the problem is that the chips with a perfect alignment on all the pins of an LQFP depends on the manufacturer and those are only available in large quantities and for the big manufacturers.

author: bob91343
author_rank: Super Contributor
timestamp: November 03, 2020, 04:03:06 am
content: I would suggest making a simple jig that will bend all pins and put them in a straight line. You could do that with some aluminum for instance. Hold it in your hand, form the leads, and it should work.

author: ejeffrey
author_rank: Super Contributor
timestamp: November 03, 2020, 04:28:43 am
content: Where are you getting your chips? How are you handling them?I've had this happen a handful of times (using assembly houses not my own PnP) but it's pretty rare. I did have one LQFP-64 where a whole row of pins was bent up enough to not solder. It doesn't happen often enough for me to worry too much but I assume the bending happens during assembly.You shouldn't be pressing down with the PnP. The leads should be aligned well enough to touch the solder paste with no pressure.
LQFP100 0.5mm pitch solder mask - Page 1
Forum section: electronics / projects

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: July 08, 2013, 06:32:51 pm
content: For my current project, I want to use an LQFP100 with 0.5mm pitch. So even if I reduce the pad width to 0.25mm, the space between the pads is just 0.25mm. As the solder mask swell is usually around 0.1mm, this leaves less than 0,1mm between the pads. Even if I'd reduce the solder mask swell to 0.075mm, the space between the pads would be only 0.1mm. I kinda doubt this is enough for the typical solder mask process to produce a reliable bridge between the pads.So would it be better to refrain from solder mask between the pads in this case? Or is 0.1mm usually enough?I'd like to use Jackaltac to produce the PCBs btw.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: July 09, 2013, 05:38:09 pm
content: For the sake of completeness, I'll answer myself.Got a reply from Jacktaltac:"... the minimum bridge of solder mask is around 3 mil (0.076 mm) so your 0.1 is ample"

author: colotron
author_rank: Contributor
timestamp: July 09, 2013, 09:22:39 pm
content: I guess it depends on the manufacturer, his equipment and processes.In my country most of the local pcb manufacturers (the ones that work with low quantities) can't do a solder mask dam smaller than 6 mils.Also check with your manufacturer things like drill/via sizes (not all sizes are available), min. annular ring, via tenting, routing/and any other assumption you have made to design the pcb.
LSpice to Vero/Stripboard Layout/autorouter - Page 1
Forum section: electronics / projects

author: Sirus
author_rank: Contributor
timestamp: November 03, 2013, 01:03:27 am
content: Could a kind soul recommend a freeware LiteSpice net to Vero/strip board board manual layout or autorouter.I have loved Veroboards for a long time, and I really don't want to order or make etched boards to my designs unless there in the 20+.I usually bread board, make the circuit again in Lspice for a record, then spend an age trying to squease it on a veroboard.There is a theoretical bunch of flowers for the best suggestion, ;P.TTFN

author: IanB
author_rank: Super Contributor
timestamp: November 03, 2013, 01:10:23 am
content: You can get protoboards that have the same strip layout as a breadboard. If you have the circuit built on a breadboard you can then transfer it directly to the protoboard.

author: edavid
author_rank: Super Contributor
timestamp: November 03, 2013, 01:17:04 am
content: Maybe this will help you:http://blog.g4ilo.com/2010/01/stripboard-magic.htmlBTW it's LTspice, not LSpice or LiteSpice.

author: Bored@Work
author_rank: Super Contributor
timestamp: November 03, 2013, 01:21:00 am
content: Blackboardhttp://blackboard.serverpool.org/is specifically made for stripboard layout and contains NGSPICE simulation. The problem is the limited documentation.

author: Sirus
author_rank: Contributor
timestamp: November 03, 2013, 01:50:31 am
content: Cheers B@W,That's pretty cool, better than what I am using, Can I use a net list and say where to make the cuts?Just down loaded it, the man needs a medal. and donations! If it could import a Lspice net list and shows where to make cuts, I would give a big donation, no problems.Bunch of flowers to you B@W.TTFN

author: Sirus
author_rank: Contributor
timestamp: November 03, 2013, 01:56:57 am
content: edavid,Yup, I know it's Linear Technologies Spice. Lite and L is just a software habitual term.You also get a bunch of flower though. Haven't downloaded it yet but the description looks like it's just what I wanted. Awsome
< 20MHz DDS IC with burst mode (10-bit DAC output)? - Page 1
Forum section: electronics / projects

author: Sparky
author_rank: Frequent Contributor
timestamp: November 19, 2018, 11:12:13 pm
content: Hello forum!I'm having difficulty finding a suitable DDS for my project. I'm after something a little specific and I've found a few good options but not the perfect device. I thought a quick post here would be worthwhile if anyone happens to know a suitable part! Would greatly appreciate any thoughts on this!Requirements:10-bit DAC output (voltage or current)maximum frequency output ~10MHz, with 1Hz or better resolution3.3V operation, low power, small sizeTriangle or Sawtooth waveform at the outputTrigger or sync inputBurst mode to generate pre-programmed n waveform periods at outputOptions:AD9833, AD9837, AD9838Of these AD9837 is my preference and it's perfect in terms of low power, small size, 28-bit resolution, MCLK <= 16MHz, 10-bit DAC VOUT, triangle output possible.Limitations are:- continuous wave output (no burst mode), and- no sync/trigger, so hard to synchronize with other signals.Best option I found:AD5930This has a DAC with current output, is larger package, only 24-bit resolution, but still acceptable. Main benefits are CTRL pin for triggering/sync and pre-programmable burst mode of 'n' complete waveform output cycles. These two are really key features and it's great.However, AD5930 is designed for frequency sweep applications so the output waveform frequency increases by deltaF each time CTRL is triggered. It would be great to set the deltaF to zero, but it doesn't look possible! For my application I would need to reset or reprogram the DDS after each burst of n waveforms so that on the next trigger of CTRL pin I have the same frequency. This is possible (there's a few microseconds to available to do so), but I would like to avoid this reset/reprogramming if I can.Anyone know of a DDS like AD5930 that had burst mode and triggers, but without the sweep capability?Will appreciate any suggestions!Sparky
Lt 3083 internal opamp grade ? - Page 1
Forum section: electronics / projects

author: DanP
author_rank: Newbie
timestamp: April 22, 2014, 07:46:27 am
content: Hi all,anyone knows what is the grade of the op-amp used internally in LT 3083 ? I need to track it's output voltage on another power line and I would use an op-amp which is close to what LT 3083 has inside in terms of performance, not an overkill.Thanks all

author: Bored@Work
author_rank: Super Contributor
timestamp: April 22, 2014, 10:20:32 am
content: Why not use a second 3083? Connect its set pin to the output of the first. This way you get to use a true and original 3083 internal opamp for tracking.However, if you want to do it with an external opamp there shouldn't be any specific requirements on that external opamp. Everything good enough to give you the desired regulation of that second rail should work.BTW, note that the 3083 has a similar flaw as the 3080. The 3083 can blow up if the voltage difference between the set and the output pin exceeds 10V. The 3080 is even more critical when it comes to the difference between the two pins.

author: DanP
author_rank: Newbie
timestamp: April 22, 2014, 03:00:20 pm
content: Quote from: Bored@Work on April 22, 2014, 10:20:32 amThanks for this. I missed it on the first pass on maximal ratings in datasheet.
LT Spice - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: August 30, 2015, 01:56:24 pm
content: Does anyone know if LT Spice's models are assuming the worst case specifications for their products, the typical case or the best case?

author: tggzzz
author_rank: Super Contributor
timestamp: August 30, 2015, 02:02:29 pm
content: Quote from: kc3ase on August 30, 2015, 01:56:24 pmThat entirely depends on who wrote the model and what their objectives were. All models are simplifications; many spice models (LT Spice included), aretoosimple - they just indicate what the device manufacturer wanted you to simulate.

author: SaabFAN
author_rank: Frequent Contributor
timestamp: August 30, 2015, 03:07:54 pm
content: Quote from: DiligentMinds.com on August 30, 2015, 02:46:12 pmTrue dat!Designed a circuit that worked beautifully in LTSpice, but oscillated like crazy when built on the actual boards. Blew 30€ on that.So don't believe everything the computer tells you.

author: tree
author_rank: Regular Contributor
timestamp: August 30, 2015, 03:23:36 pm
content: I spoke with some guys from LT how they design their models for their switching converters and the answer: it varies. They try to capture the behavior as closely as possible. If I recall correctly they use the Ridley model for their converters which captures most of the behavior pretty accurately.

author: Bassman59
author_rank: Super Contributor
timestamp: August 31, 2015, 01:12:54 pm
content: Quote from: SaabFAN on August 30, 2015, 03:07:54 pmIn fairness to LT, if we are talking about using LTSpice to simulate their DC-DC converters, I've used it to simulate several power-supply designs based on their parts, and the designs worked correctly on the bench. Of course, you really have to pay attention to the dire warnings about layout on the data sheet. You can't just plop parts down on the board in any old fashion and expect it to work. One can extend this caveat to all circuits. The board must be considered a component.And as we well know, a simulation is only as good as the models used, and finding accurate models of inductors and transformers is not easy.
LT Spice adding components  - Page 1
Forum section: electronics / projects

author: AndrewHodgson
author_rank: Contributor
timestamp: November 25, 2019, 02:53:06 pm
content: Hi,I'm trying to add the HC74 library to LT spice but I can't get the simulation to work.I download HC74.lib and add it into the folder lib\sub.I open that file in LT SPICE and create the component by right-clicking on the .SUBCKT line.I save the component and open it in a new design.When I run the simulation I get the following errors no matter what i try.WARNING: Can't resolve .param speed1=(speed)WARNING: Can't resolve .param speed1=speedWARNING: Can't resolve .param td1=1e-9(9-3-3)4.0((vcc1)-0.5)(speed1)I've attached a screenshot and the library file saved with the .txt extension.Thanks

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 25, 2019, 03:55:32 pm
content: I remember trying what I think was the exact same "library" in LTSpice, and never got it to work. I think the "speed" parameter is an extra parameter that should be passed in the Spice line (you can add it when you right click on the component?), but there were tons of others errors after that, so I gave up (and found the model I was looking for elsewhere). If anyone manages to use this "library", don't hesistate to chime in.
LT-SPICE blows up when I sim this. Any ideas why? - Page 1
Forum section: electronics / projects

author: ModernRonin
author_rank: Contributor
timestamp: July 17, 2010, 12:44:03 am
content: Someone on Reddit posted a question about a PWM circuit using a 555 timer.I was getting screwy results (max current 1.4mA) when simming his circuit using the generic nMOSFET, so I replaced it with an IRFP4668. Nice bog-standard mosfet, I thought.Now the simulation is hanging up and never finishing. It seems like it always goes insane when the transistor switches on for the second time. (First switch-on is fine.)Here's the LT-SPICE file:http://www.gully.org/~mackys/crazy.ascAny ideas what's going on here? Am I doing something wrong? Is LTSPICE just screwed up in the head?

author: lamja
author_rank: Contributor
timestamp: July 17, 2010, 01:35:35 am
content: Hi.If you change your L1 from 10 (H) to 10m (mH) it works just fine... Are you sure it should be 10H?I often get this problem, but changing some value (extreme high or low) usually do the trick.R6 and C4 looks like they have no purpose.

author: Zero999
author_rank: Super Contributor
timestamp: July 17, 2010, 07:56:38 am
content: This is a classic, I remember doing a simulation of a circuit with a 10F super capacitor and was wondering why it wasn't working, until I realised that Spice is case insensitive and it treated 10F as 10fF which is 10×10-15F and is probably less than the capacitance between the pads for an 805 SMT resistor.

author: jahonen
author_rank: Super Contributor
timestamp: July 17, 2010, 08:29:49 am
content: General rule is that you never enter a unit in component values in SPICE. That helps to solve most stupid mistakes. Only killer feature are prefixes m and meg, where m = 10-3and meg = 106. Or, alternatively use the exponent notation, 10k = 10e3, 1 M = 1e6 etc.Regards,Janne

author: ModernRonin
author_rank: Contributor
timestamp: July 17, 2010, 04:28:48 pm
content: Quote from: pilleyuppo23 on July 17, 2010, 01:35:35 amI'm sure. It's a 2.5 HP, DC electric motor. 18.5A @ 130V.QuoteYou're right, they don't. I was just fooling around there. Taking them out doesn't change the sim blowing up, though.

author: ModernRonin
author_rank: Contributor
timestamp: July 17, 2010, 05:15:29 pm
content: Thought the 555 might be causing some sim weirdness, so I took it out and put a voltage source configured for PWM in there instead. Still blowing up:http://www.gully.org/~mackys/crazy2.asc

author: jahonen
author_rank: Super Contributor
timestamp: July 17, 2010, 06:10:48 pm
content: Try changing the solver to "Alternate", seems to run much better than the normal solver. (Simulate -> control panel -> SPICE -> Solver = Alternate). MOSFETs seem to be difficult for the simulator sometimes.Regards,Janne

author: ModernRonin
author_rank: Contributor
timestamp: July 18, 2010, 07:05:43 am
content: Beauty! Thanks a lot!