hybridfree/eevblog-posts huggingface dataset:
Capacitor Self Resonance - Page 1
Forum section: electronics / projects

author: itdontgo
author_rank: Regular Contributor
timestamp: February 21, 2014, 01:32:26 pm
content: Hi,This must be a common query but it's hard to find info in general capacitor datasheets. Does anyone have a rough guide to the typical value you will find an MLCC will resonate at. What would be ideal would be a graph showing resonant frequency vs. capacitance. From the industry I'm involved in I know just under 1GHz you'll be looking at experimenting with caps of around 33-39pF, and about 10-15pF for about 2GHz... 100MHz 10nF etc...Is there a better way than soldering them in and trying it out? I understand ultimately you're going to have to do this to get it right but a rough starting guide would be ideal!

author: itdontgo
author_rank: Regular Contributor
timestamp: February 21, 2014, 01:34:39 pm
content: I should point out I'm referring to power supply decoupling. I'm not making LC circuit without the L or anything!

author: TheRuler8510
author_rank: Regular Contributor
timestamp: February 21, 2014, 01:59:07 pm
content: There are a few options:1. Look at the vendor's website or catalog closely, as the info may be in there somewhere.2. Look for a capacitor model or measured data, from which you can derive the info.3. Ask the sales guys for the info.4. Use Di-Labs CapCad program for an approximate reading on self resonance.5. Use similar products by other vendors as approximate idea.Good Luck.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 21, 2014, 04:20:20 pm
content: Beware that most often, caps resonate against either each other, or the ground plane(s), the inductance being trace length (if any) and vias. Low impedance bulk (large ceramics, aluminum polymer) are generallyundesirable because they don't reduce the Q of the circuit. Tantalum is best for this (which is unfortunate if you need hot-plugging or have unusually beefy supplies to filter, because large current surges or reserves are the downfall of tantalum), because of the moderate and stable ESR and low ESL. (You could also use one of those low-ESR types with an explicit series resistor, at some expense to ESL and parts count.)As for self resonance, assume the cap has the inductance of a piece of wire its size. The resonance in circuit depends fully on ESL, trace length and so on. There's no stray inductance or lead length in a chip capacitor, only overall package length.Tim

author: dannyf
author_rank: Super Contributor
timestamp: February 21, 2014, 04:35:12 pm
content: Someone already pointed this out but those devices typically oscillate in a circuit (aka "against other components"), not by themselves.I would say that with the use of smd parts and in a power supply, you are likely to have other pressing issues to worry about than resonating mlcc.
Capacitor sizing for PF correction - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: April 15, 2018, 04:34:29 pm
content: How do I know how much capacitance is needed to correct the power factor of a single phase AC motor?Surely the capacitor would be connected in parallel to the load but will a capacitor of a higher mF rating help the PF get closer to unity?

author: Benta
author_rank: Super Contributor
timestamp: April 15, 2018, 05:50:35 pm
content: Hard to say, when we don't know the size of the motor.But generally, it's not desirable to go for a PF higher than 0.9 with a capacitor. The problem is resonance, which you want to avoid.

author: SeanB
author_rank: Super Contributor
timestamp: April 15, 2018, 06:10:14 pm
content: Good rule of thumb is to aim for a 0.9PF lagging at the highest, so size the capacitor so the reactive current is around 60% of the motor full load current, and place it close to the motor, so the circulating currents do not have a long length of cable to lose energy in. In most cases aiming for 0.8PF is best, as most Utility calculations for load factors assume this as a load spec, and it generally does a good job of controlling harmonics as well. Going for 1.0 will be bad, as then you have a parallel resonant circuit, and this can generate high voltages at power off that destroy the motor and capacitor as they carry on resonating after power off till the energy is dissipated, plus turn on is stressful for switchgear.in most cases power factor correction is not really needed, unless you are in industrial applications with massive motor loads, and there the most common way is to instead use a synchronous 3 phase motor that is driving some large constant load, and exciting it to have a leading power factor instead, giving you useful power and correction at the same time. for small motors you really do not need PFC, though for inverter drives there is a good call to have power factor correction capacitors and line reactors, to keep noise down the power lines low and to reduce harmonic generation from the diode bridges, along with also reducing stress in the diodes by increasing conduction angle in them. But this is mostly used with multiple inverters that together are sharing a DC bus for energy recovery, and where they all are powered from the same supply by common contactors. There you use the manufacturers specs for PFC and reactors more than anything else.
Capacitor Spec Chart Many Questions - Page 1
Forum section: electronics / projects

author: dexters_lab
author_rank: Unknown
timestamp: February 19, 2017, 11:16:32 am
content: Been looking up the details of a capacitor, i can't find it's details in the manufacturers catalog so it maybe a custom part and there's a couple of columns in the spec i am not sure what they mean, can anyone offer some advice to decipher the caps specification?the cap is pictured and has a part of E51.L12-202R20, the closest match in the catalog is E51.L12-102R20E51 is the seriesL12 seem to be the physical size, L being 64mm diameter and 12 being 120mm long20 seems to be the capacity, 2.0uFthe rest of the part number '2R20' i have no ideaOn the spec chart...for starters column UBBDC (V) is DC Volts but what does the 'BB' mean?the Î (kA) (with the circumflex) i am not sure what that means either?I am going to guess that IS(kA) might be Surge kA and IMAX(A) could be continuous/repetitive amps?The others are pretty obviousAnother confusing thing is the cap label implies it's UNis 1170v but then it says AC next to it, yet UNin the catalog is used as DC volts and Uris used for VRMS

author: CatalinaWOW
author_rank: Super Contributor
timestamp: February 19, 2017, 02:05:15 pm
content: Electronicon's app notes for the series explains much of this. It is both English and German so comprehensible to us with limited German skills.http://www.electronicon.com/fileadmin/inhalte/pdfs/downloadbereich/Katalog/neue_Kataloge_2011/200.003-020021_App-notes.pdfThe capacitance is three digits of the part number, the third digit being an exponent. I can't explain the base for the exponent, but you can work it out easily.BB refers to the terminal to terminal voltage (German acronym). As opposed to BG, terminal to case voltage.

author: dexters_lab
author_rank: Unknown
timestamp: February 19, 2017, 02:14:54 pm
content: thanks, i'd not seen the app note
Capacitor start motor, changing direction - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: August 29, 2021, 11:38:53 pm
content: I picked up a band saw that was missing the original 1/2HP ac motor. I thought I could use a spare 1/2 HP motor I had laying around from an old drill press that I converted to 3-phase with VFD. The surplus drill press motor fits perfectly, however the direction of rotation is reverse to what is needed for the band saw.I opened it up hoping to reverse the start winding and this is what I found. The diagram is my best guess as to how the wiring actually is based on ohm meter readings.The blue wire appears to be common to both windings, so I don't think I can reverse it without pulling the field windngs out and bringing out a second wire, any experts out there to verify my best guess.I can't actually see the connections from the colored wires to the magnet wire.

author: CaptDon
author_rank: Super Contributor
timestamp: August 30, 2021, 01:56:57 am
content: Looks like you may have to do some surgery on it to find the other end of the start winding.I worked at a machine shop many years back and we removed the start capacitor completelyfrom the motor on a drill press. You had to turn on power and manually give the chuck a spinin the desired direction to start the motor. This was super handy for using 'reversed drills' thatare used to drill out broken screws/studs/etc. Of course you needed common sense when'spinning it up' to not get clothing wrapped into the chuck!! We never had any mishaps, but wehad intelligent people who knew and accepted the dangers. (Kind of like when we were allowedto jump off moving trains doing classification in the freight yards!!!! Can't do that anymore!!!!Had to dumb it down to the lowest common denominator!!!) I used to put rolling stock from behindthe locomotive into a siding ahead of the locomotive facing the direction of travel!!! That is whenI had a brakeman and conductor as my crew. (Back when railroading was fun and unionsdidn't suck and you had work/family balance!!!)

author: Jester
author_rank: Frequent Contributor
timestamp: September 02, 2021, 03:31:50 am
content: I was able to access the field windings enough to separate the common connection (run & start) and bring out a separate wire for the start winding. It was a bit easier than anticipated.It's now working CCW!
Capacitor type for charge pump - Page 1
Forum section: electronics / projects

author: Simon
author_rank: Unknown
timestamp: April 26, 2018, 02:03:35 pm
content: I am doing a charge pump (18-36V @ 25mA) I am not certain if I can use an electrolytic capacitor due to the ripple current. Even putting a resistor in series with the capacitor to control current spikes I still have peaks of 600mA in a simulation which is beyond the spec of most small electrolytics at 120Hz never mind 1-10KHz. Is a ceramic a the best choice here ? I could of course use tantalum as I am putting 33R in series with the flying capacitor so it won't be prone to the typical failures of tantalums.

author: doktor pyta
author_rank: Frequent Contributor
timestamp: April 26, 2018, 02:24:45 pm
content: Little experience from few days ago:TC7660 charge pump operating with three (input, floating, output) MLCC 1u/25V ceramic capacitors produces audible sound (10kHz).Not very loud but sometimes irritating.

author: Simon
author_rank: Unknown
timestamp: April 26, 2018, 02:37:16 pm
content: Quote from: doktor pyta on April 26, 2018, 02:24:45 pmDon't worry there will be more noise to worry about than that

author: Buriedcode
author_rank: Super Contributor
timestamp: April 26, 2018, 02:46:04 pm
content: I have used this appnote before when adding charge pumps to boost converters:http://www.ti.com/lit/an/slva398a/slva398a.pdf

author: Simon
author_rank: Unknown
timestamp: April 26, 2018, 03:04:23 pm
content: Well I came up with the attached, it uses a mosfet driver and will be pulsed from a micro controller and I will try and introduce some current measurement on the main regulator this is driving so that I can cut the pulses off, reduce duty to lower the output voltage.
capacitor v loss - Page 1
Forum section: electronics / projects

author: tekguy
author_rank: Contributor
timestamp: September 26, 2022, 12:45:02 am
content: hi all,i am checking a cap on a chineese component tester out of cuircit,its marked as 1j100,i assume 100nf markings,ir reads 102nf,with a .1% vloss,i assume thats leakage?,,is that good or bad?,cheers Paul.

author: moffy
author_rank: Super Contributor
timestamp: September 26, 2022, 03:40:55 am
content: Loss is a measure of AC resistance vs reactance i.e. the component of current in phase with the AC excitation across the capacitor relative to the 90 degrees current. A 0.1%, loss, or tan(delta) is good, mylar caps are normally around 1%.

author: Vovk_Z
author_rank: Super Contributor
timestamp: September 26, 2022, 11:09:43 am
content: I usually compare measured parameters with a datasheet. Since there isn't Vloss in a datasheet - it is hard to say something for sure.If you are talking about a film cap - I guess Vloss is a senseless parameter for them mostly. There is a sense to look at Vloss for electrolytic caps if you don't can't measure a leakage current.
Capacitor value type ident tdr analyser bit miffed - Page 1
Forum section: electronics / projects

author: cleanworkbench
author_rank: Regular Contributor
timestamp: December 23, 2017, 02:51:06 pm
content: Want to build this circuit but got a bit of confusion here .The three caps up at the power on switch are 1 , 22 and 470uf values , has the author made an error , like missed out the point in front of the figures then it would seem to make sense more, should these be electrolytics or poly types , it just doesnt seem to add up to me , these are well in the electrolytic range if they are there,s no indication of that on the diagrame , none ?.Are they for decoupling ??.http://mirror.thelifeofkenneth.com/lib/electronics_archive/Time-Domain_Reflectometry_On_A_Budget.pdfAny help appreciated

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: December 23, 2017, 03:14:18 pm
content: Pretty sure they are standard electrolytics. Polarity is quite obvious despite the incorrect schematic symbol. They used three values to acomodate different frequencies of noise and ripple I guess.

author: Audioguru
author_rank: Super Contributor
timestamp: December 23, 2017, 03:17:00 pm
content: Yes, the capacitors decouple (filter) the battery voltage. I would use a 0.1uF ceramic with a 47uF electrolytic. The 3rd capacitor is not needed.The 0.1uF capacitor filters high frequencies and an electrolytic will not work as well as a ceramic type.

author: cleanworkbench
author_rank: Regular Contributor
timestamp: December 23, 2017, 05:10:14 pm
content: thanks for the i/p , anyone else care to add .Just consolidating my thoughts here .

author: David Hess
author_rank: Super Contributor
timestamp: December 23, 2017, 05:47:48 pm
content: The extra capacitance is there to prevent sagging from the battery's ESR toward the end of the pulse so I would leave all three capacitors as shown.

author: cleanworkbench
author_rank: Regular Contributor
timestamp: December 23, 2017, 07:47:00 pm
content: Thanks again for the i/p will have a go tomorrow and see whats what , never made a tdr before so all new territory .
Capacitors between AC and DC on rectifier - Page 1
Forum section: electronics / projects

author: JJalling
author_rank: Unknown
timestamp: August 19, 2015, 01:15:02 pm
content: Hi,can someone please explain the purpose of the capacitors C15, 16, 17 & 18 in the following figure? Why connect the AC and DC side with capacitors?Thanks, Jonas

author: langwadt
author_rank: Super Contributor
timestamp: August 19, 2015, 01:21:24 pm
content: they are there to reduce the switching noise from the diodes

author: JJalling
author_rank: Unknown
timestamp: August 19, 2015, 01:22:38 pm
content: That was my initial guess. Thanks./Jonas

author: Seekonk
author_rank: Super Contributor
timestamp: August 19, 2015, 01:36:05 pm
content: That is kinf of a left over idea from olden days when rectifiers were iffy. Take a standard 1N4001. Test those and at least 80% will test at over 800V reverse if not higher.

author: codeboy2k
author_rank: Super Contributor
timestamp: August 19, 2015, 03:40:37 pm
content: The oft-referenced Hagerman doc about snubbers on power supply rectifier diodes.www.hagtech.com/pdf/snubber.pdfHis testing shows that best results are obtained with a series resistor and a capacitor across the diode.
Capacitors in series for higher voltage applications - Page 1
Forum section: electronics / projects

author: Red_Micro
author_rank: Regular Contributor
timestamp: May 19, 2020, 09:48:31 pm
content: From the first circuit below, the red area is a startup network. The App Note states:QuoteMy question is: if I have three capacitors in series, then the bus voltage is divided by three. Now I don't have a single middle point, but two middle points. Is it okay if I connect my startup transistor in the second point, like shown in the picture?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 19, 2020, 10:19:55 pm
content: Sure... but, will that point have enough minimum voltage, and is the resistor divider dimensioned such that 1. adequate startup current can be delivered and 2. the upper caps won't be overvolted in the process?Tim
Capacitors of a Dickson multiplier - Page 1
Forum section: electronics / projects

author: raff5184
author_rank: Regular Contributor
timestamp: July 12, 2016, 01:32:38 am
content: Hi, I am designing a 4 stage Dickson multiplier, but I can't find a formula/procedure to calculate the capacitors values. Please can you provide a link or some material.Thank you

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 12, 2016, 07:10:56 am
content: https://en.wikipedia.org/wiki/Voltage_multiplier#/media/File:Dickson_voltage_multiplier.svgPick a frequency, say 100kHz. The minimum C value (for the caps connected to Phi1/Phi2) should be around C = Io / (2*pi*F*Vo), preferably 3-10 times larger, or more. Likewise, the diode or switch resistance needs to be a similar fraction of R_L = Vo/Io. The final (Vo) cap should be larger still.You don't need a funky waveform. I don't know why they've drawn it that way. Complementary square waves are fine.Tim
Capacitors rms current sharing? - Page 1
Forum section: electronics / projects

author: AcHmed99
author_rank: Contributor
timestamp: September 30, 2011, 02:44:21 pm
content: I

author: amspire
author_rank: Super Contributor
timestamp: September 30, 2011, 03:01:06 pm
content: You want to go for low esr electrolytic capacitors, and they all have a maximum current rating specified. If your capacitor doesn't have a maximum current specified, then it is the wrong type of capacitor. 100uF sounds a bit low for 2A. Anyway, capacitors will deteriorate with age so if you want the circuit to last, I would go for an electro with a 4A rating.It all comes down to the heat in the core of the electro - the hotter it is, the quicker the ESR will rise causing it to get hotter still till it fails.If necessary, put several electro's in parallel.Richard

author: amspire
author_rank: Super Contributor
timestamp: September 30, 2011, 03:21:17 pm
content: 2A is just a fair bit of RMS current. Is the inductance big enough so that it has a fairly constant current all the time?2A RMS sounds like maybe 4A average current in the primary. Is it something like that?

author: amspire
author_rank: Super Contributor
timestamp: September 30, 2011, 08:49:10 pm
content: I am dubious, but absolutely try out.

author: shadewind
author_rank: Frequent Contributor
timestamp: October 01, 2011, 10:05:46 am
content: Every low ESR cap has the RMS current specified and if italien not enough, you can use more than one in parallel. The MLCCs will also reduce the current seen by the electrolyte.
Captive screws - M3 - Page 1
Forum section: electronics / projects

author: DTJ
author_rank: Super Contributor
timestamp: February 08, 2023, 05:41:30 am
content: I'm looking at options for captive screws for some sheet metal.I'm sure I've seen some M3x8mm pozidrive screws on domestic electronics and I'm trying to find some without any luck.There's lots of fancy and EXPENSIVE ($2 to $4 each) captive fasteners but no affordable ones.I really only need something like a standard M3x8 pozidrive panhead with a millimeter or two of thread removed from just under the head.Has anyone used or seen a source of this sort of screw?Cheers.

author: EPAIII
author_rank: Super Contributor
timestamp: February 12, 2023, 08:54:23 am
content: I don't know if they will ship to Australia, but looks like around $0.20 each (USDs) in relatively small quantities. That should give you a price point to look for.https://www.mcmaster.com/captive-panel-screws/socket-head-captive-panel-screws/McMaster is not known for the best prices. If you need thousands to millions, look for screw and fastener companies in your larger cities. You can probably beat that price by a factor of 10 if you are buying a large enough quantity.But then, even McMaster would drop the price if the quantity is large enough - but you have to drop a dime and TALK TO THEM. If you are buying in bulk, you can not get the best prices for anything by just using a web search. You have to talk to a person. But not for a dozen or two.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 12, 2023, 11:44:39 am
content: I saw that too. Then, I carefully examined the column headings. A 6-32 x3/8 is $4.28 each for 1-4. The "packages" refer to retainers.See attachment. The lowest price I found for a smallish screw was about $2.30 each, but shipping was high. I think you are stuck paying way too much for low volume (<1,000) or making them yourself on a lathe. If finish isn't important, you could try a file and a drill press.

author: TimFox
author_rank: Super Contributor
timestamp: February 12, 2023, 03:40:56 pm
content: Unfortunately, McMaster does not ship outside of North America, and US only for personal orders.That's a shame, since if you can't find the object there, you probably don't need it.In Chicago, if I place a small order at 2 PM it arrives at my house the next day by UPS.

author: DTJ
author_rank: Super Contributor
timestamp: April 16, 2023, 05:11:51 am
content: Thanks for the input people.

author: Phoenix
author_rank: Frequent Contributor
timestamp: April 16, 2023, 05:46:52 am
content: Keables are an Australian nut and bolt specialist. They might be able to help.https://www.keables.net.au/
Capturing audio using Arduino Yun-->USB audio card-->MAX9814 opamp - Page 1
Forum section: electronics / projects

author: yamanoorsai
author_rank: Contributor
timestamp: June 12, 2015, 09:17:05 pm
content: I am trying to record audio using aMAX9814 amplifier + microphoneand a USB audio card + microphone. I connected the microphone as shown in the figure below:I verified that the microphones work correctly by connecting them to microcontroller based recording circuit. The recording was clear. So I decided to connect it to a USB Audio card which is in turn connected to an Arduino Yun.I have 3 different USB audio cards. I am using ffmpeg on the linux command prompt to capture audio. The audio is generally muffled and has a lot of static noise with all of the three audio cards. Am I expecting too much from these audio cards? Are they all going to be affected by static noise? Is there a fix to record audio using cheap off-the-shelf records?
Capturing data from a sefty sensor power line - Page 1
Forum section: electronics / projects

author: yamanoorsai
author_rank: Contributor
timestamp: December 20, 2013, 09:47:55 pm
content: I asked a similar question in this forum earlier and this question is somewhat related to my previous question. I am trying to use a garage door sensor in one of my projects. The garage door sensor consists of an IR transmitter + receiver. The receiver has a red LED that turns off whenever the IR beam is interrupted.I am trying to make use of the receiver output in my project. I have attached an oscilloscope capture of the receiver output. It is a 330 Hz signal and it consists of peaks and "dips" as shown in the attached picture. The sensor is powered at 12V and this was captured across the power supply terminals (garage door sensors do not have separate sensor outputs).The peaks are really small and I have no clue about detecting this signal using a microcontroller. Using a potential divider circuit did not help. I was not able to use opamp as a difference amplifier either. What would be the ideal method of detecting this signal
Capturing high voltage sparks with a DSO - Page 1
Forum section: electronics / projects

author: mcinque
author_rank: Unknown
timestamp: June 11, 2014, 06:45:34 pm
content: I'm about to do some "poor man ESD discharge tests" on my last circuit, using a BBQ piezo igniter.Basically I will put some sparks on the front panel of the case, near and over all the pushbuttons and objects that could be touched by the user.By using the one shot triggering on my DSO, I'd like to capture any glitch or spike that could go on the pcb instead the discharge path I've created.I believe that BBQ piezo igniters can produce about 5.000V and I don't have a high voltage probe, so I was guessing that using 10x 1MOhm 1/2W resistors in series should do the job, but since my lack of knowledge often makes me do stupid things, I guess that it's better to ask an adviceWhat do you suggest?

author: Neilm
author_rank: Super Contributor
timestamp: June 11, 2014, 07:13:43 pm
content: EMC ESD strikes have a very fast profile, so you would need a decent scope to get the spark transient. At these frequencies, the inductance of a wire wound resistor will have significant effect - probably over whelming the actual signal.Also, your scope input could be easily be affected by the strike which can seriously affect the triggering meaning you don't see any real data. (I've tried to capture 15kV strikes using various probes, without any real success)
Capturing intermittent AC line dropouts/glitch using SIGLENT SDS1102X - Page 1
Forum section: electronics / projects

author: KD4CCF
author_rank: Contributor
timestamp: November 09, 2018, 04:01:06 am
content: I have a problem where something is triggering my 120VAC 60Hz UPS system to run very briefly (1 to 2 seconds max).I've been unable to identify that any appliance/HVAC/Refrigerator running coincides with the trigger.It could be the AC dropping out, or noise on the AC signal. I even replaced the circuit breaker in the panel.It might not do it again for 5 minutes, or 5 hours, so unattended operation is needed.I'd like to utilize the SIGLENT SDS1102X to trigger on whatever anomaly that could be causing the UPS unit to trigger.I'm not sure how to set the scope to do this... I'm a bit new to all the advanced triggering modes available)Thanks in advance.

author: tautech
author_rank: Super Contributor
timestamp: November 09, 2018, 07:25:39 am
content: The frequency of such an event makes this tricky.Have a look at setting a Pass/Fail mask and the RTC on board it should give some indication of when it occurs.If you set it up to Stop you can see the event and that will give clues how to set a trigger for it so you can then attempt to correlate it to a cause.You can find the Pass/Fail menu in Utilities.Here's what it might look like setup and running without an event to trigger it:

author: KD4CCF
author_rank: Contributor
timestamp: November 09, 2018, 11:25:57 pm
content: Is there a cursor/marker at where the pass/fail has failed? I have it on fail-to-stop.

author: tautech
author_rank: Super Contributor
timestamp: November 10, 2018, 12:38:49 am
content: Quote from: KD4CCF on November 09, 2018, 11:25:57 pmYes it will stop the tests and flag the waveform in red where it passes outside the mask.You can also have it send a logic signal to the rear BNC if you need to interface with another device.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 10, 2018, 05:29:05 am
content: Does the UPS have an old fashioned RS232 output? Use that as a trigger.

author: KD4CCF
author_rank: Contributor
timestamp: November 14, 2018, 09:07:47 pm
content: After running various pass/fail windows the scope would generate a fail on a real tight window on normal line fluctuations, where the UPS did not trigger, yet the UPS would trigger when the scope did not generate a fail. Go Figure.I did find the magic sequence of the UPS front panel buttons to reduce the sensitivity, and all is now happy.
Car battery input protection - Page 1
Forum section: electronics / projects

author: mayor
author_rank: Regular Contributor
timestamp: December 07, 2023, 02:34:34 pm
content: Hello, I'm working on a CAN bus project, and started to look more closely at input protection for the car's 12V. I don't know if there is protection along the way where I will be tapping in, but assuming not to be on the safe side.I happened on this TI schematic, and am not sure how the Zener (D10) wouldn't burn itself out in case of excess voltage? Shouldn't there be some current limiting, say with a resistor?I'm looking for any practical advice to protect the input to the regulator.

author: TimNJ
author_rank: Super Contributor
timestamp: December 07, 2023, 06:20:16 pm
content: Whether the zener will burn out depends on the nature of the transients you expect on the supply rail, and the effective source impedance. Harsh transients like 'load dump' are very hard to protect against, if you need an economical, reasonably sized solution. Some people may say "don't care" about load dump, because of a statistically low likelihood (?), and just make sure that the device will fail safe if hit with a load dump surge (properly fused). Other transients can be reasonably suppressed with a medium sized TVS in an SMA or SMB package, e.g. 400-1000W rated range, without additional series impedance.Yes, adding impedance will limit the zener/TVS current/dissipation. If your device has a low current draw, say <100mA, then a resistor may be suitable. You still need to mind peak power dissipation during transients, and may want to use a surge/pulse rated resistor if necessary. Add as much series resistance as you can reasonably tolerate.

author: mayor
author_rank: Regular Contributor
timestamp: December 07, 2023, 07:54:13 pm
content: Quote from: TimNJ on December 07, 2023, 06:20:16 pmThanks,the device can use up to ~400 mA, so I don't really want to add much impedance at all. I think I may opt for a TVS as you suggest, along with a resettable fuse if I can find one. In the event of a load dump, I am ok for the device to shut down.
Car battery replacement ? - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: May 04, 2019, 10:12:50 am
content: So my car's battery is dying (6 years old) and I would like to replace it.It's a Varta 80 Ah AGM model that costs 230$ to replace however since I'm looking to save up some cash would I be fine using a 74 Ah lead acid Varta instead?The later is 100$ so huge price difference and I wonder if it would be worth the savingsThe car is a 2012 mercedes C300 4matic blueefficiency without engine start/stop feature.

author: Gyro
author_rank: Super Contributor
timestamp: May 04, 2019, 10:49:44 am
content: If it hasn't got fancy start-stop features, then any battery with sufficient capacity and CCA (Cold Cranking Amps) rating will work fine. Not that cold cranking is likely to be a problem in the Lebanon.

author: sokoloff
author_rank: Super Contributor
timestamp: May 04, 2019, 01:32:17 pm
content: I'm a big fan of the AGM batteries, particularly in underseat installations where acid leakage can go undetected much longer and rust out the car.Things to check:Will it fit? It looks like the 74Ah lead-acid is smaller than the stock AGM battery. That's usually OK, as long as whatever holds the battery in the car can still work.Are the terminals the same type (side vs top post)?Are the terminals on the same side as original? (some batteries have positive and negative on the "other" side from each other)Electrically, it'll be "mostly fine". AGM and lead-acid batteries chemistry is slightly different and the charging targets are different. It's possible that the car is targeting the charge profile for AGM which will slightly overcharge the lead-acid, leading to a lower battery life and higher likelihood of leakage. For a 7-year old car, you have to decide if that's worth it or not. (I'm generally one to keep cars 15-20 years, so 7 year old car isn't getting into the "clunker; who cares?" territory for me.)I'd replace with another AGM, but I realize that's not financially equal decision.The lead acid substitute will "work".
Car battery to 5V microcontroller as input. - Page 1
Forum section: electronics / projects

author: siclano
author_rank: Newbie
timestamp: September 25, 2024, 12:52:17 pm
content: Hello, new to the forum.I'm developing a module for customized cars that should be able to read something around 8 switches connected to the car battery as a digital signal in a 5V microcontroller.It would be nice if it could detect switches that closes to 0V and switches that closes to the battery positive voltage (single pole switches), but i don't know how to make the signal apropriate to my 5V microcontroller - for those who may be interested, i'll use a Microchip SAMC21.I don't know if there would be a way to make a pin compatible to 0V and battery voltage switches detection, but that is not the main problem right now.I uploaded a solution i came up to, but i've never desgined something for automotive purposes and what i've heard about is that it can be a very harsh and noisy environment, so i don't know if ideas like OPAMP as as divider or a MOSFET as a level translator would make it.Therefore, i would really appreciate some help here! Even if it's just a tip about automotive PCB design or things i should be aware of.Thanks!

author: Kjelt
author_rank: Super Contributor
timestamp: September 25, 2024, 01:06:47 pm
content: If it is only 0v and Vcar I would use optocouplers.If you power your uC from the car battery make sure you protect the 5V from all the carbattery nasties.Enough examples at the internet, use polarity diode and TVS diode a DCDC converter that will survive Vcar-7V to Vcar+15V , last voltage should be way lower than the TVS voltage and a large electrolytic before the dcdc converter with at least a Vcar+15V voltage rating.

author: DavidAlfa
author_rank: Super Contributor
timestamp: September 25, 2024, 01:17:06 pm
content: A resistor divider of 100k/47k should work pretty well.

author: Andreas
author_rank: Super Contributor
timestamp: September 26, 2024, 05:27:05 am
content: Hmm,only some point that come into my mind:- LM339 is not automotive qualified (use a LM2901 with AEC spec instead)- directly at the input pin you need ESD protection (8 or 15 kV)- there is no current limiting resistor (e.g. in case of reverse battery) between input pin and comparator- usually you want to have some kind of low pass filter against RF or EMI pulses- normally one would also appreciate some hysteresis after the input low passwith best regardsAndreas
Car Beeper water damage question - Page 1
Forum section: electronics / projects

author: ImpulsiveJames
author_rank: Contributor
timestamp: May 07, 2022, 02:31:57 am
content: Sooo.... we went rafting and.....had a little accident....Water got in our car unlock beeper and stopped working. I know very little about RF/transmitting. I actually just picked up my first Oscilloscope last week and am just getting acquainted.So far I've used the oscilloscope to trace the signal from the main controller chip to the N2t transistor, then it looks like it goes through the cap to the L3 (inductor?), then the antenna. I guess I'm having some issues testing these inductors, they don't seem to be passing any current/can't measure any ohms. The Cap also doesn't make sense to me, won't the cap smooth out the data signal over the air?

author: inse
author_rank: Super Contributor
timestamp: May 07, 2022, 07:03:01 am
content: I suppose to clean the PCB with alcohol and a toothbrush to remove the flux and allow better inspection.Did you build this yourself?It looks like hand soldered and 3D printed

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: May 07, 2022, 09:02:39 am
content: Inductors that do not read resistance are open.As to value you need a 2nd working unit for comparison.Jeff

author: ImpulsiveJames
author_rank: Contributor
timestamp: May 07, 2022, 07:18:31 pm
content: Quote from: inse on May 07, 2022, 07:03:01 amI did that before, but was poking around again soldering/desoldering and didn't clean it back up - my bad.I just have it held with a 3d printed magnetic pcb holder

author: ImpulsiveJames
author_rank: Contributor
timestamp: May 07, 2022, 07:41:32 pm
content: Once again, I'm just getting into this stuff and am still a total noobI've been doing some more readings, and do have a second one that I've been testing with. I do see one major difference with the oscilloscope. These pictures are from Auto mode probing each side of the N2t transistor (NPN?)Bad Unit CollectorBad Unit BaseGood Unit CollectorGood Unit BaseSnap shot of the N2t transistorAm I right to assume the emitter is connected to ground? Did I get the terminology right?
Car engine temperature controller resets its memory - Page 1
Forum section: electronics / projects

author: HonkMaster
author_rank: Newbie
timestamp: May 15, 2023, 08:44:21 pm
content: Hi! I have a weird problem. I made an adjustable circuit that turn on radiator fan on when engine reaches a certain temp(90degree in my case) and stop it when engine temp reaches a lower value(80 degree for this car). This is for a modified off road car.I used a simple electronic thermostat that have a user interface for adjusting temps and other settings. The onboard relay is only 5A rated, that's why i used a 12v 40A car relay after it.The circuit is working fine for 2-3 h, but suddenly it's loosing all programed settings. This is only mounted in car,I test benched it, without the 12v relay and other addons. Just 12v noninterrupted for 2 days. I used a mosfet and a Arduino board to turn it on and off every 1 min for 20h and no memory loss.I resoldered every connection, and added more caps for filtering, but the problem is still there.I was thinking that some interference form the car electronics are causing this. First culprit is the fan relay that is located right behind the module, but I'm not sure. Any advice will be helpful. Thanks!

author: floobydust
author_rank: Super Contributor
timestamp: May 15, 2023, 09:23:34 pm
content: Many things can cause the problem you are having. From the partial schematic, there is no transient protection and not such a great circuit so I'd expect it to not work properly.Where is the temperature sensor, is it one or two-wire? Your grounding can also be an issue.Is "onboard 5V reg" a 7805 or 1117?C4 is not done right, it is supplying for the entire car and not just your board, as well as hard on the ignition switch arcing to charge it.Do you have a back-EMF diode across RL1 coil? or RL2 coil?
car interior light circuit - Page 1
Forum section: electronics / projects

author: jason1983
author_rank: Newbie
timestamp: February 21, 2015, 03:14:21 am
content: Hi I'm Jason, I'm trying to design a light circuit for my car. I'm not new to electronics but designing using semiconductors is not my strong point. I'm hoping I'm in the right place for some advice? Basicly what I'm after is a circuitry that fades the interior light on when the car is unlocked an stay on until either a certain time has lapsed (60 seconds) or the car ignition it turned on or door is locked again. Also the original 0v door open/closed signal must work. When the light goes out I also need it to fade out. I would be very gratefully for some advice please. Many thanks Jason

author: DmitryL
author_rank: Regular Contributor
timestamp: February 21, 2015, 10:20:14 am
content: Quote from: jason1983 on February 21, 2015, 03:14:21 amIMHO the main problem is how to get state signals you need from your car (locked/unlocked etc.), i.e. to know when do you need to switch lights on/off.The rest is very simple. For example, for my Honda jazz I made a LED interior light "module" that replaces standard bulb and fades in when the power applied. You press that light, and it gradually increases brightness within 5 seconds or so. Nothing but a bunch of LEDs, a PIC controller, small FET, and other small parts. The solution is simple, because the circuit has only one signal - power

author: jason1983
author_rank: Newbie
timestamp: February 21, 2015, 01:13:23 pm
content: Hi thanks for your reply, I can get either a pulse 0v or 12v for both the lock/unlock signal.

author: Rerouter
author_rank: Super Contributor
timestamp: February 22, 2015, 08:51:46 am
content: for the fading it would be more economic to use a cheap micro (look up arduino and attiny if you are new to it)then you just have your permernant power connection, the lock status, and the ignition status going in, you use something like an NPN transistor to handle the switching / fading of the light with the micro controlling it,so for that you could get away with, 1x LM7805 (and supporting parts), an attiny chip (crystal and reset resistor maybe), 2 resistor dividers for the inputs, and a NPN with base resistor,for the code, they have on there site examples for fading an LED, all you would need to do is tweak it to happen when your inputs are triggered,
Car noise canselling - Page 1
Forum section: electronics / projects

author: hansibull
author_rank: Regular Contributor
timestamp: May 30, 2014, 10:20:27 am
content: Hi!After watching Dave's video #600 about OP-amps, I started thinking about how you could invert a signal to "make it go zero".If you have an inverting OP-amp connected to your AUX plug in your car, you could, theoretically cancel the noise.It would be fun to test this out, so I guess I'm going to build one and test!The problem is that if you speak, or listen to music, the OP-amp will also invert these signals.So, how can you make the OP-amp invert just a specific signal (car noise), and not voices and music? Does is exist audio signal processors that could fix this?

author: Marco
author_rank: Super Contributor
timestamp: May 30, 2014, 10:38:23 am
content: You will just get an oscillator. For such a comparatively massive space with such huge and variable distances between the listener and the speakers it can only work for very low frequencies (ie. where wavelengths are multiple meters). Of course you'd need pretty big speakers as well at those frequencies.

author: mjkuwp
author_rank: Unknown
timestamp: May 30, 2014, 10:53:30 am
content: should clarify.... I think OP meant to cancel interior noise of the car on the inside. This is done to help make phone calls possible and has been done in some car models to cancel noise that exists in the drivetrains. Noise cancelling through the built-in audio system is cheaper than quieting the mechanical system.

author: rob77
author_rank: Super Contributor
timestamp: May 30, 2014, 02:57:48 pm
content: using a microphone and an OPamp it won't work because of the delays (phase shift). you would have to do some digital signal processing to get some usable results.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 30, 2014, 09:01:02 pm
content: dont cancel the noise you wont hear if somebody horn from behind or if you hit something...
Car Power-bank Project - Page 1
Forum section: electronics / projects

author: Lasherž
author_rank: Contributor
timestamp: August 19, 2020, 08:18:08 pm
content: This is beneath the qualifications of pretty much everyone on this site I think, but I figured I'd post anyways and see if anyone had some good critiques or suggestions for how to do this a better way.I've got 2 cameras in my vehicle that offer a 24/7 recording option that loops just in case there's an event while parked. I've tested them to use about 11 watts constantly each, and because they have no programmable shutoff for the current state of the battery I definitely don't want them feeding from the car's electrical. I've explored programmable relays that will drop out at 12.6V, which is significantly better than letting the battery drain, but idle these devices will still quadruple my car's stock power draw due mostly to their bright displays.I've moved on since then to using a power bank typically used for tablets and phones and it works great, however I need one that can supply 11wx2 at once whether charging or not. The one I have seems to be teetering on the edge of what the cameras require since sometimes one will drop out and go into a reboot loop. The idea is to let the car fast-charge the bank while it's on and then if the bank goes dead it goes dead, but most of the time it will be charged enough to record the parking lot. This isolates my car's battery completely while still giving days worth of recording.The question is for a USB 3.0 or 3.1 port, if you use a 2.0 cord will the power delivery still be 3/5A respectively through that old wire? I understand that I'll be missing 5 pins when using an older standard plug. The 2.0 ported power packs I'm seeing (and own) provide 5V 1A hookups, but even 5V 2A would be barely enough. I suspect when it goes through its new file compression sequence it might exceed the rating of the bank. USB ratings are a right mess lately from what I can tell.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 19, 2020, 10:28:17 pm
content: Just replace the stock car battery with a deep cycle, then you'll get plenty of capacity.

author: Lasherž
author_rank: Contributor
timestamp: August 20, 2020, 12:52:06 am
content: Quote from: NiHaoMike on August 19, 2020, 10:28:17 pmPerhaps if I kept the stock battery and got a diode to charge the deep cycle, running an accessory line from just the new one. I don't want two weeks without using the car to prevent me from starting it if I go on vacation, etc. I figured the lithium bank would be superior for space concerns too but obviously a deep cycle addition would address the issue in a more long term way. I'm sure it could handle more charging cycles. The main nice thing about the bank though is I can keep it tucked away in my center console and it doesn't require a diode or any consideration when hooking it up or disconnecting it from the rest of the car after an extended period of not starting.I may end up either using multiple power banks or going with a more involved setup like that if the USB 3.0 or 3.1 standard does rob the 2.0 backwards compatibility of power capability.
Car rpm meter idea - Page 1
Forum section: electronics / projects

author: Hrvoje-CRO
author_rank: Contributor
timestamp: December 20, 2017, 06:11:22 pm
content: Hello,I have an idea to make project which should act like this:When car is no moving, leds are running slow and its speed is determined by the speed of the vehicle. So it should act like led chaser whose speed depends on the speed of the vehicle.Can it be done with old school components such as ne555+cd4017?Thank you in advance!

author: CJay
author_rank: Super Contributor
timestamp: December 20, 2017, 06:50:58 pm
content: Absolutely, you can use the 555 to 'smooth' and stretch ignition pulses to clock the 4017 or perhaps your car has a pulse sensor for the speedo?

author: max_torque
author_rank: Super Contributor
timestamp: December 20, 2017, 06:58:34 pm
content: If the idea is "to make the most difficult to read and most completely useless rev counter ever made" then yes, that sounds perfect.......