hybridfree/eevblog-posts huggingface dataset:
Capacitors: Energy Charged in Parallel vs Energy Discharging in Series - Page 1
Forum section: electronics / beginners

author: MarcusDarkmoor
author_rank: Newbie
timestamp: March 01, 2021, 01:49:20 am
content: Hi all,First time posting:I understand somewhat the Capacitor paradox when discharging one capacitor into another, but I seem to have come across a variation(?) of this but with no current flow...Charge two capacitors in parallel e.g. 10uF 100V. E = 0.5 CV^2 on EACH one = 0.5 x 10uF x 100 x 100 = 0.05J per capacitor, 0.1J total.Now connect them in series ready to be discharged: Effective capacitance = 5uF, Voltage = 200V. E = 0.5 x 5uF x 200 x 200 = 0.4JSimply by reconfiguring the connection we have 4 times the energy, or so it seems. I don't believe in 'free' energy. What gives?It's not the same as the discharging one cap into another, as that deals with current flows and time constants. In this example there is no current flow (yet).Thoughts? Explanations?

author: WattsThat
author_rank: Frequent Contributor
timestamp: March 01, 2021, 01:58:33 am
content: Show your work. You’ll see there is no free lunch.Edit: perhaps what you’re missing is that you have one capacitor at 0.1J? No idea how you arrived at 0.4J.

author: ejeffrey
author_rank: Super Contributor
timestamp: March 01, 2021, 02:51:59 am
content: You just did arithmetic wrong. 0.5 * 5 uF * (200 V)^2 = 0.1 J

author: amyk
author_rank: Super Contributor
timestamp: March 01, 2021, 02:52:45 am
content: 200 * 200 * 5/1000000 * 1/2 = 0.1Arithmetic error.

author: TimFox
author_rank: Super Contributor
timestamp: March 01, 2021, 03:46:56 am
content: With the math corrected, this is the basis for the "Marx Generator" high-voltage pulse generator.

author: Capernicus
author_rank: Frequent Contributor
timestamp: March 01, 2021, 05:23:03 am
content: 2=1, im afraid is the answer to this...

author: MarcusDarkmoor
author_rank: Newbie
timestamp: March 02, 2021, 06:03:22 pm
content: Oh God I feel SO dumb! lol. Calculator fingers syndrome....I did it 3 times just to check. Somehow made the same mistake 3 times. Thank you for pointing out my obvious and stupid mistake, and being nice about it too....
capacitors form factors - Page 1
Forum section: electronics / beginners

author: raff5184
author_rank: Regular Contributor
timestamp: February 23, 2017, 10:59:14 pm
content: hi is there a formula/table that, given the capacitance value of a capacitor, gives me the dimensions (and possibly the currently smallest dimensions) such as the volume, of the available off-the-shelf capacitors?

author: Aodhan145
author_rank: Frequent Contributor
timestamp: February 23, 2017, 11:05:15 pm
content: You can get most in nearly any form factor/size, just go on a component distributor such as Farnell or Digikey, go to the capacitors filter by your desired capacitance and check the remaining sizes on the filter and choose from there. That would be the easiest way to do it.

author: Brumby
author_rank: Unknown
timestamp: February 24, 2017, 05:46:40 am
content: Don't forget to include the working voltage.For a given capacitance, they tend to get bigger with increased voltage.
Capacitors??? How big? - Page 1
Forum section: electronics / beginners

author: TINMAN265
author_rank: Newbie
timestamp: January 11, 2024, 10:40:28 pm
content: I use arduinos to trigger relays and often they are triggering locks. The issue I have is that some of the locks I use are fail secure 12V locks that often draw up to 3 amps... BUT only for milliseconds and it is usually at least 1-5 minutes before they retrigger. I have usually used a 12v SLA battery to meet the needs of these power hungry locks. I would like to have additional options and I thought that a nice capacitor might give just the bump needed to facilitate a clean release. What size do I need? how do I size it so I know how you came to that conclusion? I have to wire it in to the common of the relay so it is ready to go when the relay closes the appropriate path... What does that look like in a wiring diagram (which wires to which leads)? Thanks for any help!!

author: Ian.M
author_rank: Super Contributor
timestamp: January 11, 2024, 11:27:59 pm
content: Q=CVQ is charge (current multiplied by time), C is capacitance, and V is voltage, specifically change of voltage. Therefore if you need to supply 3A for 10ms without dropping more than 2V you'd need at least 15 mF (15000uF) of capacitance.Then you have to consider the capacitor'sESR, which directly contributes extra voltage drop by Ohm's law (V=IR), so smaller supercapacitors not intended for pulse discharge applications, probably wont be suitable for your application due to their higher ESR.

author: TINMAN265
author_rank: Newbie
timestamp: January 12, 2024, 07:35:15 pm
content: thats pretty big... probably just end up sticking with SLA battery then. Thanks for the information!

author: selcuk
author_rank: Frequent Contributor
timestamp: January 12, 2024, 07:49:34 pm
content: I think you need diodes instead of capacitors. Please check page 8 of this document about switching inductive loads like door locks.https://mediac.industry.panasonic.eu/p/2020-08/ti_relay_general_application_guidelines_en.pdf
Capacitors in a Fluke multimeter - Page 1
Forum section: electronics / beginners

author: windsmurf
author_rank: Frequent Contributor
timestamp: April 07, 2019, 10:55:11 am
content: I've been looking at the back of a Fluke 26-3 meter, and see these fairly large capacitors (7.3mm length on the bigger ones).I have a couple of noob questions regarding them.What is the manufacturer/brand of these caps?What is the red stuff underneath these caps?Is the notation used to signify their values a standard? E.g. I can't decipher voltage or tolerance... does it not exist on these?

author: Cnoob
author_rank: Regular Contributor
timestamp: April 07, 2019, 11:30:33 am
content: The red stuff is some form of glue, used to keep components in place for wave soldering.As for the capacitors I found they they are Tantalum capacitors. [https://www.alibaba.com/showroom/tant-cap-100uf.html/url]Markings are I think are 47uF 10V working and 15uf 10V working as for manufacture no idea.other one is 4.7uf 20V working

author: tooki
author_rank: Super Contributor
timestamp: April 07, 2019, 11:43:59 am
content: They're Vishay polymer tantalum caps. The "K5" and "K7" markings are date codes meaning May 1998 and July 1998, respectively. The 2 in a circle means Vishay. Then the value is microfarads and volts, so 4.7-20, 47-10, and 15-10 mean 4.7uF 20V, 47uF 10V, and 15uF 10V, respectively. They do not have any tolerance, temperature, or model markings.https://www.vishay.com/capacitors/tantalum/tantalum-polymer/http://www.vishay.com/docs/40110/faq.pdfThe red stuff is, exactly as Cnoob said, glue to secure the components for wave soldering.

author: windsmurf
author_rank: Frequent Contributor
timestamp: April 07, 2019, 07:13:32 pm
content: Thanks Cnoob, and tooki for the complete explanation!

author: retiredcaps
author_rank: Super Contributor
timestamp: April 08, 2019, 04:08:31 am
content: Fluke 77 III service manual has the values and schematics.
Capacitors question - Page 1
Forum section: electronics / beginners

author: Shadow85
author_rank: Newbie
timestamp: December 19, 2015, 09:59:23 am
content: Hi,can anyone tell me whats the difference between thosealiexpress.com/item/NEW-25-x-104-0-1uf-50V-Monolithic-Ceramic-Capacitor/32223692261.htmland those?aliexpress.com/item/Free-Shipping-1000pcs-lot-Ceramic-capacitor-104-0-1UF-100NF-Capacitor/1876545628.htmli got a kit and one of the yellow ones is missing so i'm asking if i can replace it with the brown one.
Capacitors - Scopes - Beginner - Page 1
Forum section: electronics / beginners

author: tvl
author_rank: Newbie
timestamp: January 31, 2019, 03:52:44 pm
content: Remove

author: Johncanfield
author_rank: Regular Contributor
timestamp: January 31, 2019, 10:41:23 pm
content: What are you using for a voltage source?

author: MavMitchell
author_rank: Contributor
timestamp: February 01, 2019, 03:56:44 am
content: Is this noise matching the pulses on the control wire? Is this noise visible all the time, or only while the servo is in motion?

author: rstofer
author_rank: Super Contributor
timestamp: February 01, 2019, 06:56:14 pm
content: I wouldn't take the servo power from 5V if I could avoid it. It would be far better to have a separate 6V supply with the ground sides tied together.If I couldn't do that, I would connect the servo power all the way back at the PSU and nowhere near the CPU.You can always add more capacitance but you might also look at adding 0.1 ufd ceramic capacitors right at the CPU pins and another very close to the servo. These smaller capacitors are more effective at eliminating high frequency noise (which I really don't see anyway).Basically, it seems you have too much resistance in your power source to the servo. I'm assuming the voltage is sagging. You really should show a second channel with the servo signal so we can align the supply voltage signal with the servo PWM. Trigger on the PWM and show a couple of cycles.In fact, add the second trace first and the post the results.
capacity - Page 1
Forum section: electronics / beginners

author: Mepakos
author_rank: Contributor
timestamp: September 02, 2019, 09:54:08 am
content: Which capacity value is effective between A and B? Is this right?

author: Circlotron
author_rank: Super Contributor
timestamp: September 02, 2019, 10:24:50 am
content: 3n3 and 47n = 3n083n08 + lower 2n2 = 5n285n28 and RHS 2n2 = 1n55 <----
Capcitors and Current - Page 1
Forum section: electronics / beginners

author: Falcon69
author_rank: Super Contributor
timestamp: May 07, 2013, 06:24:27 am
content: I searched for an hour tonight, and I just can't find information on this. For a DC circuit, using a 1uF 0603 size ceramic capacitor rated at 16 volts, what is the maximum amount of current that can flow through it without damaging the capacitor? For a 0805 size? For a 1206 size?It seems all manufacture data sheets only say maximum voltage. Never mentions current.

author: IanB
author_rank: Super Contributor
timestamp: May 07, 2013, 07:02:28 am
content: For electrolytic capacitors look on the data sheet for the maximum RMS ripple current. For small ceramic capacitors I don't think this is a big concern.When considering DC, the average current through the capacitor is of course zero. For a small ceramic cap the peak instantaneous DC current (e.g. if you apply the rated voltage to a discharged capacitor) is not a limitation. The capacitor can handle it whatever it is.

author: MacAttak
author_rank: Unknown
timestamp: May 07, 2013, 06:25:50 pm
content: For DC current, a capacitor is open-circuit. If you have any current at all goingthroughit, then you've fried it and it has fused short.

author: ejeffrey
author_rank: Super Contributor
timestamp: May 07, 2013, 07:33:39 pm
content: If you can find an ESR spec, you can estimate the maximum ripple current by assuming a power rating similar to a resistor of the same package size. So an ESR of 1 ohm in a 1/8 watt package can handle 350 milliamp RMS current. Ceramic capacitors have very low ESR, so this is rarely an issue.If you are talking about a supply filtering, it is important to remember that the DC current 'flowing past' the capacitor into the load has no effect at all. You need to calculate the ripple current that actually flows through the capacitor. That is, during each cycle, the capacitor will charge and discharge a little bit. That charge/discharge cycle is the ripple current, and it is what is important for capacitor ratings.
Caps in Devices with power switch - Page 1
Forum section: electronics / beginners

author: Veketti
author_rank: Regular Contributor
timestamp: March 16, 2025, 08:42:21 am
content: I've been wondering that in appliances which have single pole power switch and when having non polarized plug (like schuko) , depending on which way you plug the mains, switch either cut the neutral or hot wire. In case it cut the neutral wire, are the capacitors under strain in that devices power supply compared to situation that the hot wire is cut?

author: PGPG
author_rank: Frequent Contributor
timestamp: March 16, 2025, 03:51:10 pm
content: Except may be filtering capacitors at input the rest of circuit 'do not know' which wire is hot and which neutral.

author: BillyO
author_rank: Super Contributor
timestamp: March 17, 2025, 02:37:58 am
content: Capacitors that can go across AC don't care which is line and which is neutral. AC alternates polarity.

author: golden_labels
author_rank: Super Contributor
timestamp: March 17, 2025, 03:24:00 am
content: If the switch is off, there is no voltage at all. The circuit is open.
Capsule microphone biasing decoupling? - Page 1
Forum section: electronics / beginners

author: alexg
author_rank: Regular Contributor
timestamp: May 21, 2018, 05:14:56 am
content: Hi All, not sure if I worded it correctly but basically I am looking for answer perhaps to one of simplest questions: will placing decoupling capacitor (C18 in the circuit below) at the mic biasing circuit help at all to mitigate a bit of a ripple because its powered from switching regulator? Or it makes no difference or even make things worse?

author: RoGeorge
author_rank: Super Contributor
timestamp: May 21, 2018, 06:01:21 am
content: Maybe, but if you place a resistor or inductance between V33 and the node beteween C18 and the microphone's resistor, then it will certainly help, because it will create a low pass filter for the power noises only.

author: alexg
author_rank: Regular Contributor
timestamp: May 21, 2018, 02:09:37 pm
content: I have to double check, is this what you advising?

author: Zero999
author_rank: Super Contributor
timestamp: May 21, 2018, 02:27:05 pm
content: Quote from: alexg on May 21, 2018, 02:09:37 pmThat seems reasonable, although C18 may need to be much bigger for it to be effective.

author: Audioguru
author_rank: Super Contributor
timestamp: May 21, 2018, 04:19:03 pm
content: I use the mic's same decoupling for the biasing of the mic preamp like this:

author: Zero999
author_rank: Super Contributor
timestamp: May 21, 2018, 06:16:33 pm
content: Quote from: Audioguru on May 21, 2018, 04:19:03 pmYes, that will work but the mic' biasing resistor might have to have a lower value than 10k, if powered off a 3.3V supply.A bit off topic but increasing R3 to 120k in that op-amp circuit, will help to move the op-amp's bias nearer to half the supply voltage. In fact 150k or 220k may be even better, since the TL072 works better with its inputs nearer +V, than -V.

author: Audioguru
author_rank: Super Contributor
timestamp: May 22, 2018, 12:24:16 am
content: Quote from: Hero999 on May 21, 2018, 06:16:33 pmGood points.An electret mic needs at least 2V so that it does not distort fairly loud sounds and it draws about 0.5mA. Then with a 3.3 supply the resistor powering it should be about (3.3V-2V)/0.5mA= 2.6k. The decoupling resistor also needs some of the 3.3V across it so maybe the decoupling resistor will be 240 ohms and the resistor powering the mic will be 2.4k ohms. Such a low resistor value will reduce the mic output level.The minimum allowed supply for a TL07x opamp is 7V and it has the "Phase Inversion" problem. If an input voltage gets to within a few volts from its negative supply then its output suddenly goes as high as it can. I have never had an electret mic with a peak output level of a few volts (inside a drum that is played loud?).

author: Zero999
author_rank: Super Contributor
timestamp: May 22, 2018, 08:48:45 am
content: Quote from: Audioguru on May 22, 2018, 12:24:16 amThe TL072's output stage works better near the positive supply rail too, so it's still better to bias its output near the positive, than the negative rail. Unfortunately this isn't documented on the data sheet.
Capture data on a pcb data line?  - Page 1
Forum section: electronics / beginners

author: bozza
author_rank: Contributor
timestamp: February 11, 2021, 02:40:31 pm
content: Hopefully this is the right place to ask.I am fascinated by early console modchips and I am wondering how they were developed.One of the first points of entry for the chip developers must have been to capture some data from either a running console or a console that was turned off.I have glanced over flash chips and how those can be read by attaching wires to the pcb or directly to the flash chip. Reading can be done over a bunch of different interfaces for example sdio, spi, jtag and perhaps some others.Locating a serial interface can be another point of entry.What do you do if you have no idea what kind of communications are going through the pcb because it is unlabeled and the flash chips are hidden under or inside the cpu for example? Sometimes they use undocumented chips too. If you have a nand controller or a flash chip that is undocumented how do you find out which pin is the data line, clock, cmd and whatever else there is?The first PlayStation is interesting as the modchip is quite simple in theory. There is a wobbly line on the CD which cannot be reproduced by a CD burner. The line encodes 4 letters. When the console boots a disc it first reads this wobbly line. If it is present the boot process continues. If else the console locks up. What the modchip does is send these 4 letters to the cpu to emulate the wobbly line being read by the disc reader. The modchip probably sits somewhere between the disc reader and the cpu in the circuit. There is an open source version of a ps1 modchip out there.How would have the developer gone to identify the signal and how it is passed around on the pcb in the first place?I would appreciate any answers or insights at all.Thank you in advance

author: perieanuo
author_rank: Frequent Contributor
timestamp: February 11, 2021, 03:41:53 pm
content: hi,https://www.saleae.com/home2/just kiddin, there are tons of logic analyzers on the market, depends on number of data lines needed, speed, comm protocol
CAPTURE with pic 16F1829 - Page 1
Forum section: electronics / beginners

author: nikoso40@yahoo.com
author_rank: Newbie
timestamp: September 15, 2021, 11:54:38 am
content: Hi allI hope you all keeping well. I have stuckwith capture mode in this pic. I am not posting any code yet because maybe is no necessary at this point. I am trying to implement a frequency counter with this method. The code is very simple nothing too fancy. My question is if anyone has the knowledge to tell me how to set the proper registers. I think my mistake is there. I am compiling the code with no problem but the code stacks in main waiting a flag from the capture interrupt which never getting high. Checking the code with breaking points is not even getting into the ISR. This is the reason i think that the mistake is in the CCP setup and the timer.I will appreciate if someone can come up with an idea. If code is needed please let me know.Thank you your timeNik

author: jpanhalt
author_rank: Super Contributor
timestamp: September 15, 2021, 12:06:53 pm
content: I have done that same thing. Language = MPASM, which might not help much. No time to find and post the entire code. Will be back about 1300 EDT (USA). But, please show your code regardless of how basic you think it is.Are you trying to simulate it? Some chips do not simulate (MPLAB 8.92) that function with all programmers/debuggers. Be sure to check whatever device you are using.

author: nikoso40@yahoo.com
author_rank: Newbie
timestamp: September 15, 2021, 07:00:19 pm
content: HiThanks for the answer. i send the code ziped file. I have done the frequency counter on the same pic with timers and debugg with mplab and xc8 compiler with no problem. Now i am trying to learn the basics at least for capture module. I have already experimended on PWM so left me the capture and compare just you know the basics such as the setting of the registers. I think that in that point is the mistake something not doing well in the registers.Any way if you can help will be nice. If you have the same project in asm i can read it easy. Basicly i need the user.h or the registers settings.Best regards
Capxon polarity - Page 1
Forum section: electronics / beginners

author: de.leon
author_rank: Contributor
timestamp: March 25, 2022, 04:25:08 pm
content: Replacing this cap, looking for equivalent. Problem is conflicting opinions if it’s polarized or not, no data sheet on line that I could find. Need to be sure, it’s from a rather expensive digital amp board. Measured capacitance as 109 mf in either polarity but did the same with a new polarized Ruby and got the same result.Thanks for any advice

author: bob91343
author_rank: Super Contributor
timestamp: March 25, 2022, 04:53:27 pm
content: There is no capacitance of 109 mf. The F needs to be capitalized. If the m is not, it's milli; if it is, it's Mega.

author: RayRay
author_rank: Frequent Contributor
timestamp: March 25, 2022, 04:55:58 pm
content: The Capxon NP series caps are non-polar:www.capxongroup.com/download.aspx?dlfn=NP_Series.pdfSo you should replace em with such that are also non-polar, and not with regular ones.

author: wraper
author_rank: Unknown
timestamp: March 25, 2022, 04:56:08 pm
content: It's a bipolar cap. Finding the datasheet is not hard at allhttp://www.kosmodrom.com.ua/pdf/capxon-np.pdf

author: mariush
author_rank: Super Contributor
timestamp: March 25, 2022, 04:58:12 pm
content: NP means non-polarized, so no polarity ... bipolar capacitor.The label says 100uF 10v. It may measure 109uF because the default tolerance is +/- 20% ... so 109uF is within that range.You can replace with any non-polar capacitor with the 100uF rating, and voltage rating 10v or higher (ex 16v/25v/35 would be fine)Capxon is a shitty brand making shitty capacitors... you will definitely do better replacing it with any other brand.

author: Zero999
author_rank: Super Contributor
timestamp: March 25, 2022, 07:32:06 pm
content: If that's the capacitor you intend to replace, then don't bother, it's good. Solder it back in, either way round.

author: wraper
author_rank: Unknown
timestamp: March 25, 2022, 07:35:11 pm
content: Quote from: mariush on March 25, 2022, 04:58:12 pmQuite far from the shittiest capacitors available. They mostly had issues with LOW ESR series made in 2000's. Their general purpose series were OKish.
Car alternator in a bike - Page 1
Forum section: electronics / beginners

author: Guythunder
author_rank: Newbie
timestamp: August 24, 2015, 07:19:05 pm
content: I have just one question, Why do people put an auto alternator in a motorcycle. what is the reason.?

author: Zero999
author_rank: Super Contributor
timestamp: August 24, 2015, 07:20:49 pm
content: I've no idea. It sounds like a bad idea to me.

author: Andy Watson
author_rank: Super Contributor
timestamp: August 24, 2015, 07:31:11 pm
content: It performs the same function and (due to the mass production of autos) is probably cheaper.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 24, 2015, 07:39:06 pm
content: It was discussed here before about one year agohttps://www.eevblog.com/forum/projects/car-alternators-vs-motorcycle-alternators/

author: fubar.gr
author_rank: Unknown
timestamp: August 25, 2015, 07:37:27 am
content: Most motorcycle alternators are crap.On my motorcycle the rated wattage is something like 150 Watts. Due to EU regulations, the lights are always on, that means there's a constant 80-90 Watt consumption.If I turn on the brights that's an extra 50 watts, the alternator then works at nearly 100% with just a few watts left to charge the battery.
Car auxiliary lights controller. - Page 1
Forum section: electronics / beginners

author: Snops
author_rank: Newbie
timestamp: August 10, 2015, 06:27:07 pm
content: Hi.It is getting very dark very soon here in Finland and thats why I've bought few auxiliary lights for my car.I'm planning to control those light with microcontroller (ATMega168PA).The plan is to use existing headlight power (high beam) as signal to mcu so i can enable/disable aux lights with quick double blink for example. Original headlights will be in use still of course.I'm thinking to use just simple n-channel signal mosfet to drive 5V signal to mcu input (see attachment). 12V to gate and drain to input with pull up to 5v.I also want to make this circuit future proof, so what if original headlights are pwm powered? Can I just use that circuit and make software changes or just forget about that and take new approach?Also there is this canbus/monitored headlight thing so this mod should not draw a lot of current (few milliamps max).So,Is my circuit ok?What about pwm headlights as signal to mosfet?Canbus worries?Edit. ...and of course mcu will control relay that gives power to auxiliary lights etc.
Car battery 15.51V - Page 1
Forum section: electronics / beginners

author: jabalv
author_rank: Contributor
timestamp: March 06, 2019, 02:48:11 pm
content: I'm restoring old tractor and for testing electricity in it I had 2 old batteries in series circuit for 24V. (old truck and old car batteries).I had like 25-26V total, but lately I see that I had ~28V total voltage and car battery is 15.51 (seems increased)I believe 15.5V is quite high, so after googling around this could actually be dangerous as it can explode or so.Can you comment?

author: HighVoltage
author_rank: Super Contributor
timestamp: March 06, 2019, 03:16:29 pm
content: It is normal to put two 12V batteries in series on a 24V truck system and have them charge with 28VAnd if both batteries are in the same condition, they usually end up with about the same 14V across them.But if one battery is much older then the other and internal resistance has changed, one battery can charge up to a higher voltage than the other.There seems to be a definite imbalance between the two batteries and you might replace them with new and of the same type.15.1V is for sure to high.What is the charging voltage across both batteries, when the truck is running at a rpm above idle?

author: RobertBG
author_rank: Regular Contributor
timestamp: March 06, 2019, 04:46:44 pm
content: Just to add to the HighVoltage's post,15.1 is quite high but it may be just what is called surface charge. Put a little load on the battery and retest before condemning it. But besides that he's spot on.

author: jabalv
author_rank: Contributor
timestamp: March 06, 2019, 04:57:31 pm
content: I use those batteries just to test electric components. I can't launch tractor with it, cause start current is too low from both of those batteries. Just bought new ones recently with 2x 12V 1000A 180Ah. Will probably switch to those ones tomorrow.

author: jabalv
author_rank: Contributor
timestamp: March 06, 2019, 06:16:33 pm
content: It's not charging. Those 2 batteries just standing for couple weeks in that series circuit.

author: Turbochardged
author_rank: Contributor
timestamp: March 06, 2019, 09:44:09 pm
content: I agree with the others. It's to high, yet could be a surface charge. When working on batteries in series, always change them at the same time with identical manufacturer and model.

author: Gregg
author_rank: Super Contributor
timestamp: March 06, 2019, 10:58:32 pm
content: You kind of answered your own question when you stated that the batteries couldn’t start the tractor. Your purchasing two new identical batteries is certainly is a good solutionAt least one of them is in very bad shape and continued charging of them in series will only make things worse. The battery with the lower voltage at rest may have a shorted cell which causes all of the rest of the cells to see a higher than nominal voltage. The one that reads 15.1 may be the better of the two and with a little more testing may be a good enough battery for testing low current 12VDC items. Hook up a 12 volt headlight and leave it on for about 5 minutes, then read the voltage; if it drops below 10.5 volts, it is pretty much worthless.
Car CAN buses - Page 1
Forum section: electronics / beginners

author: Erwin Ried
author_rank: Regular Contributor
timestamp: October 19, 2022, 12:46:29 pm
content: I understand that there is 2-3 different buses in most cars. I want to remote start and switch the climate controls on my kia optima phevKnowledge you can share?(I tried to install a OEM remote start kit for the gasoline version… but did not work, tries to start but fails I guess because the hybrid does not start the gasoline engine inmediatelyhttps://photos.app.goo.gl/8BRGg1W6pW1EmHFCAso now I should Arduboy-DIYit)

author: Benta
author_rank: Super Contributor
timestamp: October 19, 2022, 04:59:32 pm
content: Quote from: Erwin Ried on October 19, 2022, 12:46:29 pm2...3? There are many more.

author: Erwin Ried
author_rank: Regular Contributor
timestamp: October 19, 2022, 06:42:41 pm
content: But isolated from each other? Which ones? Because for example thinking on kia/hyundai I think there is 3, one base for important stuff, brakes etc, other for the cluster and secondary stuff like climate and other exposed for diagnostics (based on what I have read)
Car charger schematic questions - Page 1
Forum section: electronics / beginners

author: brainwash
author_rank: Frequent Contributor
timestamp: February 20, 2013, 04:31:17 pm
content: My moderately expensive car charger died a few months ago. It's an Einhell brand though I'm pretty sure it's made in China. I paid around 40-50E which is almost double what I paid for the Turnigy Accucel 6.Well, I have no main reason to resurrect it with its current design, but I can still not fully understand how this thing works. I'm attaching the reversed engineered schematic, there might be a few mistakes. I have no idea what the zenner value is. Charge fuse is rated for 15A, there is a panel ampmeter that shows "12 eff / 8 arith" at the end of the scale.So, can anybody explain me how this thing was supposed to work? I'm guessing it has something to do with the difference between the positive rail voltage and the thyristor turn-on voltage.

author: SeanB
author_rank: Super Contributor
timestamp: February 20, 2013, 07:05:22 pm
content: The charger is based on an Everyday electronics kit, costs $5 here by me, complete with PCB.I works by the zener voltage being compared to the battery voltage, and if the battery voltage is lower Q2 turns on and then Q1 turns on the thyristor to charge the battery. This is done at 2x the mains frequency ( full wave bridge) until the battery voltage gets high enough to keep Q2 from turning on, then the thyristor stops charging until the battery voltage drops again.I have one, will take it and scan it if you want it. Similar circuit, just better.

author: brainwash
author_rank: Frequent Contributor
timestamp: February 20, 2013, 07:13:37 pm
content: Thank you.I don't know what the zener value is, I've tried a few of them in the simulation but they don't make much sense; it only seems to somehow function with a zener value of 2.5-3V.Btw, the zener was shorted and so was the NPN transistor. I just added some generic small signal transistors to the simulation, I don't think they affect the design much.

author: SeanB
author_rank: Super Contributor
timestamp: February 20, 2013, 07:31:02 pm
content: 10V zener works.
Car DC Voltage supply filter - Page 1
Forum section: electronics / beginners

author: igorbog
author_rank: Contributor
timestamp: November 14, 2011, 07:57:42 pm
content: Hi to allI have connected an preamp for mic in my car to dc source. when I connect preamp out to aux I hear a lot of noise. The preamp work good outside of a car. how can I design filter for car dc noise?

author: phil_jp1
author_rank: Regular Contributor
timestamp: November 14, 2011, 11:40:54 pm
content: What kind of preamp do you have? Is is special car stuff, or something else?You hear a lot of noise when the car engine is working or not?The easiest thing you can try is to put about 470-1000uF 50V low-ESR capacitor in parallel with 0.1uF 50V ceramic cap before your preamp (as close to it, as possible).The other way is LC filter.But that's just my guess, because I don't know what kind of preamp you have (how much current it draws, etc..).

author: sonicj
author_rank: Frequent Contributor
timestamp: November 15, 2011, 12:05:26 am
content: i would try to eliminate the noise prior to filtering it. does everything in your signal chain reference the same ground? ie: car chassis, battery neg-sj

author: Psi
author_rank: Super Contributor
timestamp: November 15, 2011, 12:10:13 am
content: An audio ground loop isolation transformers between the preamp output and aux in may fix your problem.Or you could try an isolated powersupply module to run the preamp.

author: igorbog
author_rank: Contributor
timestamp: November 15, 2011, 04:19:09 pm
content: I have connected this devicehttp://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=220837381675&ssPageName=ADME:X:AAQ:US:1123through usb to dc car converter to car dc supply.

author: phil_jp1
author_rank: Regular Contributor
timestamp: November 16, 2011, 01:49:29 pm
content: Quote from: igorbog on November 15, 2011, 04:19:09 pmThose DC-DC car power supplies (that converts car voltages to 5VDC) usually have _very_ poor output filtering, and because of that they have a really huge output voltage ripple.I guess - that's the cause of your problem.I guess your amplifier don't consume that much current, so the ideal decision is to build linear DC-DC converter using LM317. With heavy output filtering.A little bit easier way is to use 7805 voltage regulator (almost the same as LM317, but with fixed output voltage and a little bit lower ripple rejection ratio).And the easiest way is to put LC filter right before your mic amplifier. (I reckon you should try that first) I guess 1uH-10uH inductor and 100uF low-ESR cap would be enough.And for building linear DC-DC converter you can watch the video I made(I explained all the concepts there):http://jumperone.com/2011/08/lm317-adjustable-psu/Just don't pay attention to mains transformer and you can put fixed resistors instead of potentiometer.And use about 50V (at least 35V) input caps in car electronics. There could be a huge voltage spikes.
Car DVR excluave power box - tweak from 11.6V to higher cutoff Voltage - Page 1
Forum section: electronics / beginners

author: Folxs
author_rank: Contributor
timestamp: May 24, 2019, 11:13:36 am
content: Hi, I biught on Aliexpress DVR power system box, that cutoff at 11.6V to prevent deep battery discharge - but I would like to twak that treshold from 11.6V to for example 12.6V.I wanted to reverse engineer that box but I can't find datasheet for main component - that 8321 / R207B2 and that ACAA component (transistor I believe).Can anyone help me?EDIT:I added also clear PCB and bottomis normal and mirror, to better understandingof PCB connections

author: rf+tech
author_rank: Frequent Contributor
timestamp: May 25, 2019, 12:10:03 am
content: Hi Folxs,If you put forth the effort to create a schematic from the board and fill in all component values, this will improve your chances for someone to be of assistance. It would be a discourtesy to expect others to do this for you.Let's see what you can put together.RF+ Tech

author: Ian.M
author_rank: Super Contributor
timestamp: May 25, 2019, 01:05:33 am
content: Its probably *NOT* a transistor. Googling: ACAA SOT-23 SMD codeshould lead you to the part number of a Maxim supply supervisor IC.

author: Folxs
author_rank: Contributor
timestamp: May 25, 2019, 10:52:58 am
content: Quote from: Ian.M on May 25, 2019, 01:05:33 amThank You very much - I got itNow I know how this cutoff system works!There is Voltage divider of that 1% resistors to this ACAA / Maxim MAX809T, that send RESET when voltage on divider is 3.08V.So, changing this values for 3.08V for desired cutoff voltage can be doneBut - I still don't know what the heck is that mysterious SOIC8 - this is some buck converter IC

author: Ian.M
author_rank: Super Contributor
timestamp: May 25, 2019, 12:10:47 pm
content: You'd need to identify which semiconductor manufacturer uses that stylised 'B" logo on the SOIC-8 buck chip. If you are lucky, someone here will recognise it if you post a closeup of the chip.

author: Folxs
author_rank: Contributor
timestamp: May 25, 2019, 12:12:25 pm
content: Quote from: Ian.M on May 25, 2019, 12:10:47 pmI tried to, but can't find any list of manufacturers logos ;(

author: Ian.M
author_rank: Super Contributor
timestamp: May 25, 2019, 12:32:35 pm
content: There's several sites with IC logos, but I couldn't find that 'B'.
Car immobiliser utilising button combination unlock - Fury road war rig style - Page 1
Forum section: electronics / beginners

author: Richb77
author_rank: Contributor
timestamp: August 28, 2023, 11:12:53 am
content: Hi All.I am looking to better understand the task I have set myself and hoped for some help/guidance from you intelligent people.I have an old car I am restoring (1972) and security is so good on it an ice lolly stick can unlock the car and turn the ignition.I want to add a collection of "hidden" switches (1 latching and 2 momentary or 3 momentary) to cut the power/fuel pump e.t.c. until I press a sequence of buttons. Just like Furiosa had set up in the war rig in Mad Max Fury Road.Something like press button 1, then 2, then 2&3 together to unarm the car for a period of time (30s > 1 minute but I know thats a line of code).Starterstopper.com make something just like this and its not overly costly...But I fancied trying myself.I am open to all advice...but I am thinking a Microchip (which if I recall correctly is low power) looking for that first button, then it powers a relay and off i go.My problem is...I dont know where to start on the schematic!I am a mechanical engineer with layout skills. I already know i want a battery backup (like a 18350, 12v cell or maybe even coin cell(s)) so a charging circuit could be added.Does anyone know of anything similar to help me get started?Thank so much ladies and gents.

author: SmallCog
author_rank: Frequent Contributor
timestamp: August 29, 2023, 01:15:07 am
content: Sounds like a good excuse to go and get some logic gates and have a play :-)

author: Richb77
author_rank: Contributor
timestamp: August 30, 2023, 07:22:20 am
content: My biggest limitation is knowledge. I am a knuckle dragging MechE with some basic Electrical knowledge. I have programmed Pic chips, AVR a few times. I do board layout well and can draw basic schematics...But i dont have enough basic knowledge to get started.I hoped there was something similar already about but I cannot find any information even though there is some "chatter" about the Fury road scene, most about how it would be done in a post apocalyptic world.
Car LED headlight driver - Page 1
Forum section: electronics / beginners

author: paker
author_rank: Newbie
timestamp: June 06, 2021, 08:22:55 pm
content: I bought an LED headlight retrofit projector for my old 97 pickup. The sales lady said it has a built-in driver but she was mistaken. I cannot return it and would like to salvage it. I need about 13V 2A. Amazon carries "booster CV CC LED driver module" for about $10.https://www.amazon.com/TeOhk-Booster-Constant-Converter-Adjustable/dp/B07T4KDR64/ref=sr_1_7?dchild=1&keywords=buck+booster+led+driver&qid=1623010329&sr=8-7for instance. Will it meet my need? If yes, can I pot it with potting compound? Thank you.

author: viperidae
author_rank: Frequent Contributor
timestamp: June 07, 2021, 04:31:08 am
content: You will find a boost module like that will not be able to regulate when the input voltage is above the output voltage.Like when your car is charging the battery and the voltage rises to 14.4V.

author: paker
author_rank: Newbie
timestamp: June 07, 2021, 05:32:34 am
content: Thank you for the explanation. They also carry buck boost converter. It seems to have both step down and step up circuits built into one. I will try one of those. Thank you.
Car lock remote - Page 1
Forum section: electronics / beginners

author: josephny
author_rank: Contributor
timestamp: October 23, 2015, 01:27:04 am
content: I just got a DSA815 and a DS1054 and am learning how to use them, when to use them, etc. It's a hobby I've always wanted to get deeper into.Looking around for things to do with my new toys, I tried my car remote.I discovered it transmits on 314.95MhzI tried the demod feature on the 815 and listened to the signal. Using an FM demod unlock, lock and emergency buttons all sound like a series of click (or maybe short beeps).Is there any way I can further decode what is being transmitted?Thanks!

author: Cliff Matthews
author_rank: Unknown
timestamp: October 23, 2015, 01:45:09 am
content: They are called key-fob's. Something to read here:http://www.greenhybrid.com/forums/f10/some-key-fob-experiments-19844/

author: Stonent
author_rank: Super Contributor
timestamp: October 23, 2015, 02:31:16 am
content: Anything modern will use a rotating key system where each key is invalidated after use so it can't be sniffed and reused.The clicks itself are likely data bursts. Zoom in on the clicks and you'll likely see some sort of data-like signal.

author: tehmagicsmoke
author_rank: Contributor
timestamp: October 23, 2015, 03:30:03 am
content: Stonent: nice sig. If you wanna learn about the fraud of the so called "government", those who think it is OK to initiate force to protect-lol. Check out MarcStevens.net. I have kicked every ticket out of court with his motion template and script, he is the best, better than any talking head on fox news or cnn.Josephny: glad you figured out the frequency, I was gonna say if you're near me in southern oregon I'd let you use my sdr to find the frequency. If you're in new York where you are prohibited from owning a gun by men who carry guns-lol, I'd check out freekeene.com in NH. A lot of awesome people there. Wish I had some better help on your key fob, I wonder if someone on instruct ables or evilmadscientist.com or even Google has done a project?
Car monitor LVDS signal interception  - Page 1
Forum section: electronics / beginners

author: paako89
author_rank: Newbie
timestamp: June 14, 2024, 08:54:16 am
content: Morning everyone, hope all is well. I’m beginner and would like some help if possible.I’m currently working on “replacing” my car’s (2012 Range Rover Evoque) OEM navigation unit since it’s old and there’s on up to date navigation for it.I currently have installed a touch screen monitor with higher resolution which connects to my S23 ultra phone via usbc hdmi hub, so basically I have Samsung Dex in the car. Phone is connected to oem monitor via Bluetooth for audio. I’ve removed the lcd on the OEM to fix my monitor in it’s placeHere is a video of it in actionhttps://youtu.be/LVyAjBE82-c?si=9if7l-LW2xvxpTEQHowever, replacing the car’s OEM unit is impossible since it comes with all the car’s settings etc.So my plan is to intercept the cars OEM video signal and send it to my phone via usb capture device.Only major issue is that the OEM board uses LVDS for video.On the motherboard a DS90C124QVS Lvds transmitter chip sends signals to the video board which has a DS90CR286A Lvds receiver chip which then send TTL to screen. The uploaded picture shows the receiver chip and I already traced the Lvds signals. I’d like to solder wires onto the pads in picture and send the Lvds signal to a converter. Does anyone know what I could use? I don’t mind output being low quality just like the OEM .Best regardsPaako

author: jwet
author_rank: Frequent Contributor
timestamp: June 14, 2024, 03:39:46 pm
content: That's a pretty clean install- looks nice.I would intercept the signal at the LVDS side. LVDS is sometimes used as a backplane bus so it can be done. Tap off LVDS to a LVDS to HDMI converter board. Look on Ali Express, etc for an LVDS to HDMI, less than $10. You'll then have HDMI that I guess goes into another converter to get to your phone.LVDS is incredibly fast stuff and you're going to have to pay attention to signal integrity (RF like design) to not add capacitance (keep leads short) or add inductance (keep leads short). I've probed LVDS signals and it takes nice probes, etc. LeCroy has some app notes about this to give you an idea.If you're careful, you can probably get something to work and you'll likely learn a lot. Good luck.
Car Radio EEPROM Identification - Page 1
Forum section: electronics / beginners

author: mossrom
author_rank: Newbie
timestamp: August 08, 2023, 02:29:54 am
content: I am trying to identify the EEPROM where the VIN is stored on a stock oem radio (Delco 09389324) from a 2000 Buick LeSabre. In similar radios, the VIN is typically stored on an 8-pin EEPROM which reads as 24C04, 24C08, or 24C16.There seem to be 3 8-pin chips on the board. This first one looks to be an EEPROM that should read 93C46. I switched this chip from the original radio to the new one and it still shows 'LOC' on the display, and I don't think the VIN is stored there.This second one looks like a Fairchild Si4467DY, according to another thread.The third one I'm not sure about.Edit: My assumption about the first chip came fromthis database, andthis site, but may have been incorrect.My guess about the second chip came fromthis thread.

author: u666sa
author_rank: Frequent Contributor
timestamp: August 08, 2023, 04:24:15 am
content: That first AMI chip looks promising --https://www.automotiveforums.com/t899623-bypassed_theftlock_on_gm_chevy_class_ii_mp3_cd_hu.html

author: Shonky
author_rank: Frequent Contributor
timestamp: August 08, 2023, 04:56:11 am
content: Based on the pin connections, the AMI chip is highly unlikely to be a 24Cxx or 93C46 type EEPROM.24CxxPin 8 which would be VCC has a heavy track that runs away from it with no obvious bypass.Caps on pins 7 and 6.Pins 1,2,3 would be address selection for a 24Cxx but they run off elsewhere.93C46If it was a 93C46 why would there be test points and caps on pins 6 and 7 which are no connect.Similarly I don't think either of the other devices are typical memory devices.

author: AndyBeez
author_rank: Frequent Contributor
timestamp: August 08, 2023, 08:31:21 am
content: My 50 cents. Is that an I2C eeprom?

author: Shonky
author_rank: Frequent Contributor
timestamp: August 08, 2023, 09:46:12 am
content: Quote from: AndyBeez on August 08, 2023, 08:31:21 amThat is what OP is looking for however the board layouts appear to indicate otherwise.

author: MrAl
author_rank: Super Contributor
timestamp: August 08, 2023, 11:24:01 am
content: Quote from: mossrom on August 08, 2023, 02:29:54 amHi,Ok, whose radio did you steal? ha ha.Just wondering what you will do once you do find the right part number.

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: August 08, 2023, 11:36:54 pm
content: Some early delco LOC radios had a 6 digit code, accessed in two operations then this code was looked up in delco's system.Jeff

author: MrAl
author_rank: Super Contributor
timestamp: August 09, 2023, 09:41:32 am
content: Hi,Yes Buick has a system like that where you can get a code from the radio, then look it up online and get the restoring code for that radio. Not sure what the issue in this thread is though if it is that the radio just needs the security code or a whole new part.