hybridfree/eevblog-posts huggingface dataset:
Li-Ion Discharge Cutoff Voltage - Page 1
Forum section: electronics / projects

author: Mike Warren
author_rank: Unknown
timestamp: December 05, 2013, 10:22:24 pm
content: I've seen contradictory reports about how much a Li-Ion battery can be safely discharged, but 3V per cell seems to come up most often.I tested a Panasonic video camera, and it shuts off at 3.15V. Are they just being conservative?The problem I have is that I'm shutting off a circuit at 6.3V (2 cell) that's run from a generic Sony video camera battery and only getting half it's rated capacity.Although I don't expect the full capacity from an after-market battery, these batteries come from WES Components, not eBay, so I wouldn't expect them completely fake, so I'm guessing that I'm cutting off too soon.

author: mazurov
author_rank: Frequent Contributor
timestamp: December 05, 2013, 10:37:51 pm
content: What is your current draw? "Rated capacity" can easily be given for like C/20 discharge current or even less - you can learn this from battery's datasheet.

author: Mike Warren
author_rank: Unknown
timestamp: December 05, 2013, 10:48:00 pm
content: I'm drawing 380mA, which is probably very close to what the original cameras would draw from it.

author: mazurov
author_rank: Frequent Contributor
timestamp: December 06, 2013, 03:51:37 am
content: You may want to measure internal resistance and also discharge couple times at 50-100ma to see if you can get anywhere close to stated capacity. In any case, discharging below 3V at your current won't give you any noticeable increase in run time - google "li-ion discharge curve" for details.

author: Mike Warren
author_rank: Unknown
timestamp: December 06, 2013, 04:00:53 am
content: I'm only discharging to 3.3V, but I'll set up some tests on my electronic load and see what I get.

author: ohmineer
author_rank: Contributor
timestamp: December 06, 2013, 08:21:39 pm
content: Li-Ion discharge safe cut-off voltage is usually between 2.75 V and 3.0 V.Cell datasheets usually state that you can draw the full available capacity discharging at a rate of 0.2C, which in your case is 400 mA. Therefore, if your camera is demanding 380 mA, battery should give its nominal capacity (2000 mA).Sometimes, aftermarket batteries does not include cells of the capacity they show at the label. I've seen this kind of fraud hundreds of times.My second guess would be that the battery has a high internal resistance but if the pack is new this should not be the case unless it is a "second life" battery.

author: Mike Warren
author_rank: Unknown
timestamp: December 06, 2013, 08:26:38 pm
content: I found out what the problem was. The battery meter was giving an incorrect reading. I got close to 2Ah from it on the load test before I ran out of time and had to go home.So all is good. Thanks for the replies.
Li-ion,Li-Poly overcurrent protection PTC Fuse usage consideration - Page 1
Forum section: electronics / projects

author: Danesh_SA
author_rank: Contributor
timestamp: December 11, 2019, 06:51:14 pm
content: Hi all,I want to use 1206 1.0A PTC fuse in my design to protect both battery and circuit from short circuit.the device is portable and i use linear Li-ion battery charger (MCP73831) ,i just one to series PTC fuse with battery .the question is:-is it a good option for protection?-where should i place PTC fuse in my design?(just after battery conector on my PCB?)-a PTC fuse works for my protection condition or one time fuse or fusible resistor?Thanks!
Li-Ion low voltage detection - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: February 01, 2014, 02:16:40 pm
content: In a project i'm using a one cell Li-Ion battery regulated to 3.3V with a TPS78233( ldo regulator ).I want to disable the regulator when the Li-Ion cell voltage drops below 3V, i find a voltage dector that i can use the TC54 but i have one doubt.The regulator datasheet says that the a voltage below 0.4V on the EN pin puts the regulator in shutdown mode but the TC54 can pull down its output to within 0.5V of VSS.Can i use this chip to disable the ldo?If the voltage is not low enough can i use a voltage divider on the output of the TC54? I only need a voltage higher than 1.2V to enable the LDO.Thank you for the help.

author: kxenos
author_rank: Frequent Contributor
timestamp: February 01, 2014, 02:41:32 pm
content: Sure you can. A 1:2 divider would do. The issue is, the battery voltage is not going to be regulated if it is under 3,5V. I think you should look for a proper buck-boost regulator like TPS63051.

author: Unknown
author_rank: Unknown
timestamp: February 01, 2014, 03:09:20 pm
content: Thank you for the answer. My circuit stays in sleep mode most of the time and when active consume 30 mA maximun so a DC-DC it is not very efficient...i think
Li-Ion pack parallel charging with adjustable current and BMS - Page 1
Forum section: electronics / projects

author: No_Shorty
author_rank: Contributor
timestamp: June 20, 2020, 04:58:06 pm
content: Hey, so I'm just thinking through if the following is possible, and what I would need to achieve it:If I have 2 or more 14s9p Li-Ion packs capable of 15A charge and I have one charger capable of supplying charge voltage at 30A - is it possible to switch the charger to supply 30A and 'split' this between the packs? This is with both back having their own individual BMS.The charger has adjustable CC and CV, so when charging one battery it would be set up to charge at the 15A, but I was hoping I would be able to achieve the same charge time when connecting an additional pack.

author: Siwastaja
author_rank: Super Contributor
timestamp: June 20, 2020, 07:15:16 pm
content: Charger by definition is active circuit that controls current. So while it's possible to do just that, it means designing and building two such circuits; i.e., two "chargers". Guesstimating from your question, you are likely after a simple solution, which does not exist; easiest is to either charge in parallel in a dumb way (see below), or buy two completely separate chargers.Note that you can just parallel the packs and work with the single charger, but only after you have charged or discharged the packs separately to the same state-of-charge so that their voltages match closely. Be very careful here; a large voltage mismatch causes massive currents during the time of making the parallel connection, exceeding the current ratings (especially the max charge current rating of the pack which happened to be at lower voltage). Paralleling packs is hence impractical when you need to separate them again for discharge. Semi-permanent paralleling is manageable.Even with permanent parallel connection of series packs, each should have their own cell-level BMS; paralleling every balance tap as well (measuring the voltages match beforehand, again!) gets rid of this requirement.

author: No_Shorty
author_rank: Contributor
timestamp: June 21, 2020, 10:31:05 am
content: I thought that would be the basic answer.The batteries would be drained individually, so the SoC would be different and not managed outsode of their internal BMS.So essentially you need to either build two circuits after the charger each managing the CC, or as you say just buy two chargers.The question really arose as it looked like I was going to have to buy a much more powerful CC PSU than I wanted for a single battery charge, but I have since realised one of lower spec would be suitable, and buying two the much easier option!
Li-Ion series charger. - Page 1
Forum section: electronics / projects

author: PeterG
author_rank: Frequent Contributor
timestamp: September 14, 2011, 06:29:21 am
content: I have a project that runs off a pair of 18650 Li-Ion cells. I would like to build a charge system into the project.How safe is it to charge these cells in series to 8.4v?Is there an off the shelf module out there for this sort of thing?Regards

author: Psi
author_rank: Super Contributor
timestamp: September 14, 2011, 06:57:07 am
content: The risk with charging them in series is if they ever get out of sync, or one deteriorates quicker, you end up overcharging one while undercharging another. Not a good thing with lithium.Proper series chargers have extra feeds linking to between the cells to monitor their individual voltages.The cheap chargers don't bother with that and just rely on a thermal switch to cut off the battery connection if any cell starts to get hot (overcharged).

author: gregariz
author_rank: Frequent Contributor
timestamp: September 14, 2011, 07:17:06 am
content: If you need a 2 cell lithium and can put up with the size the 9v Lithium rechargables could be worth a lookhttp://www.ebay.com/itm/1pc-9V-600mA-Lithium-Rechargable-Battery-6F22-/260853220484?pt=AU_Electronics_Batteries_Chargers&hash=item3cbc104484

author: PeterG
author_rank: Frequent Contributor
timestamp: September 14, 2011, 07:20:53 am
content: I looked at the 9v. Howver i need more current, so am using 18650 cells. I am looking at building a betery charge system into the project so i dont need to remove them for charging.Regards

author: gregariz
author_rank: Frequent Contributor
timestamp: September 14, 2011, 07:25:21 am
content: The only higher C 2 cells I know off hand are the sparkfun oneshttp://www.sparkfun.com/products/10471

author: gregariz
author_rank: Frequent Contributor
timestamp: September 14, 2011, 07:35:22 am
content: Just as I replied... I made it to the end of this months circuit cellar...... on the back page is this...http://www.parallax.com/Store/Robots/AllRobots/tabid/755/txtSearch/charger/List/0/SortField/4/ProductID/758/Default.aspxbut no schematic from what I can see

author: PeterG
author_rank: Frequent Contributor
timestamp: September 14, 2011, 08:23:26 am
content: Gregariz, that board is ideal. I will wait for stock. Maybe someone in Aus will stock them soon.....Thanks.Regards
Li-ion thermistor requirement - Page 1
Forum section: electronics / projects

author: aldi
author_rank: Contributor
timestamp: October 26, 2024, 09:58:53 am
content: I'm designing a product which needs a li-ion battery as a backup. I've found a nice pack (18650 + protection) at a local supplier at an acceptable price. The pack has the UN38.3 and IEC 62133-2:2017 certifications, so I guess this is right for a commercial product.The pack has no thermistor built-in, now I'm wondering if this is a strict requirement to pass the FCC/CE certifications?I'm going to charge the battery with a BQ series charger from TI. This charger does support a thermistor, and I'm planning to place one, but this thermistor will not measure the battery voltage directly, but it will be able to prevent charging at ambient low/high temperature conditions.Will this be enough? Can anyone that has been trough this process shed some light on this?

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 26, 2024, 12:20:58 pm
content: FCC isn't going to care about how the battery temperature sensing is done, you'll have to look at UL for that. There are lots of products that have the temperature sensor on the board, just use common sense and have the sensor as close as possible.
Li-Ion usb charger : usb suspend problem - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: May 23, 2014, 02:51:31 pm
content: In a project i'm designing i have a lipo as the power source and i'm using a MCP73832 charger. Because i need to charge the battery at 300 mA i'm using a FT230X chip to enumerate the device. The usb standard says that " USB device will enter suspend when there is no activity on the bus for greater than 3.0ms" and in this mode the entire device can only consume 10 mA. Is there a way to disable the ftdi to enter the suspend mode?I've found this ANhttp://www.ftdichip.com/Support/Documents/AppNotes/AN_175_Battery%20Charging%20Over%20USB%20with%20FTEX%20Devices.pdfthat uses the cbus pins to configure the lipo charger chip (cahnge the charging current when the chip enumerates), but in theory after 3ms of no activity the HOST will put the ftdi to sleep and shutting down the charger. One of the cbus option is " Keep_Awake# " but the description says " Prevents the device from entering suspend state when unplugged " is the unplugged part an error of the datasheet? In theory i can send random data to the ftdi so there is some activity but in my opinion it is not a nice solution.

author: georges80
author_rank: Frequent Contributor
timestamp: May 23, 2014, 05:21:37 pm
content: Is this a personal project? If so, ignore all the USB standards regarding standby, suspend etc etc and just draw your 300mA from the USB port.cheers,george.

author: Unknown
author_rank: Unknown
timestamp: May 23, 2014, 11:29:18 pm
content: It is a personal project but i would like to respect the USB standard...

author: georges80
author_rank: Frequent Contributor
timestamp: May 23, 2014, 11:52:21 pm
content: For a personal project it is a complete waste of time - a laptop/pc etc will happily provide 500mA (or more). There is absolutely no need to go to the extremes of dealing with the whole enumeration process unless you like smacking your head against the wall repeatedly.cheers,george.
Li Ion USB charger… - Page 1
Forum section: electronics / projects

author: 0xFFFF
author_rank: Contributor
timestamp: April 16, 2013, 05:10:17 am
content: Recently I put together a Li Ion PS. I'm not sure if it would be of interest to anyone:barkweb-usb-li-ion-ps- A USB LiIon charger / supplyThis is the first thing I've put out in to the wild so I expect that others will find methods of improving things that I've done.Features:Configurable battery type.Can support wireless charging.Separate host and slave port.Optional 5V and/or 3.3V outputs.Optional SPI host interface.To doNice to have:Add a USB 3 hub in to the mix.Powered by the hostThe hub will attach the bq24160 and the slave device (if attached) to the host.Add an e-ink panel for status.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 16, 2013, 05:24:09 am
content: The hard to find Eink display would be overkill. A common wristwatch will run for months, even years from a single coin cell.Also, please post the schematic in PNG or PDF format.

author: 0xFFFF
author_rank: Contributor
timestamp: April 16, 2013, 05:29:28 am
content: I should call the 'To Do' list 'Nice to have'. I'm really just looking for an excuse to try and use an e-ink display.Everything is checked in. Have a lookSchematic - PDFPNG attached.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 18, 2013, 04:52:24 am
content: If you have a USB 3.0 input, you can easily check if it's connected to a USB 3.0 port by checking if the USB 3.0 ground ("GND DRAIN") is in fact connected to ground. (Bypass it with a 100n cap as close to the connector as possible to preserve the shielding aspect if you're going to use the USB 3.0 data.)
Li-Po Battery protection circuitry placement - Page 1
Forum section: electronics / projects

author: johnny
author_rank: Newbie
timestamp: April 25, 2018, 02:40:15 pm
content: Hi,I am using Li-po battery as shown in the attachment. It already has a protection circuit, which is wrapped in yellow tape. So to reduce the size of the battery can I put the protection circuitry on my PCB with the rest of circuit and fold the battery terminals?Would this folding cause any kind of damage to the battery or not?Also, what is the recommended placement of the protection circuitry, either on your own PCB or on the separate PCB attached to the battery (as they already have)?Thanks.

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 25, 2018, 03:08:25 pm
content: The closer the protection circuit to the battery cell, the better.I wouldn't recommend tampering with it. The battery tabs are pretty fragile. Is it for just a prototype or do you intend to make a product out of this?If it's just for one prototype and is not meant to be sold, you could carefully remove the tape (which is normally kapton) and fold the protection board as needed. Just be very careful, and protect the battery tabs and protection board with kapton after this. Any direct short-circuit of the battery tabs could have disastrous consequences.I wouldn't recommend using bare cells and implementing your own protection on your main PCB either for safety reasons. Another issue here is that the battery tabs should usually NOT be soldered with reflow processes (hand-soldering or otherwise), the conducted heat while soldering could badly damage the cell. The recommended soldering process is spot welding. Unless you have the right tools and know how to use them, just don't try.

author: Audioguru
author_rank: Super Contributor
timestamp: April 25, 2018, 03:42:48 pm
content: Li-PO batteries for toys look like that and their pcb does not have a protection circuit. The pcb is for the wires.

author: mikerj
author_rank: Super Contributor
timestamp: April 25, 2018, 04:18:13 pm
content: Quote from: SiliconWizard on April 25, 2018, 03:08:25 pmThe tabs on these pouch cells are most always soldered to the protection board IME.
Li-Po NTC, gas gauge and linear charger: is it possible to share NTC for both? - Page 1
Forum section: electronics / projects

author: maniel92
author_rank: Newbie
timestamp: November 05, 2021, 04:00:04 pm
content: Hello,I'm designing a new PCB and something came to my mind: I usually use a linear charger and a gas gauge for the battery-powered projects. I usually connect the NTC from the LiPo to the linear charger, and then I install a SMD NTC on the PCB for the gas gauge. I am wondering if it is possible to share the same NTC resistor among both ICs, or what should I have in consideration for this.Many thanks in advance. BR,Manuel

author: Siwastaja
author_rank: Super Contributor
timestamp: November 05, 2021, 04:08:36 pm
content: Usually not possible, these chips tend to provide internal constant current source or similar to sense the NTC. Two sources would act in parallel.If the chips have pure high impedance analog voltage inputs (i.e., you need an explicit voltage divider), then you could share the signal.

author: maniel92
author_rank: Newbie
timestamp: November 05, 2021, 04:54:35 pm
content: Ok, many thanks Siwastaja for the fast answer!
Li-polymer battery wire voltage drop concern - Page 1
Forum section: electronics / projects

author: hcglitte
author_rank: Regular Contributor
timestamp: January 15, 2013, 01:05:28 pm
content: Hi all!I am about to order 50 pcs of a li-polymer battery from China. It is a 2500 mAh 3.7 V nominal. During the design of the charger, I chose a switching type from TI. In order to be safe about noise, I added a ferrite bead on the + side to suppress switching noise. The least DC resistance 0805 version I could find was 9 mohms (3 Amps max). If charging with 1C (2500 mA), the voltage drop across the FB is 22,5 mV. Then I started to think about the cable voltage drop. The cable is 5 cm, so 10 cm total length is 21 mV. This adds up to 43,5 mV which is 1 % of the constant voltage phase (4.2V). I know this voltage needs to be very accurate in order to fully charge the battery. Since the charger IC also has 1% accuracy, we could be, worst case, 2 % off spec. Then I took a closer look at the charging curve for a Li-polymer battery. The current will decline sort of fast when entering the CV phase. So, the battery voltage may be about 4.1 V in the beginning during the CV phase, but then quickly going to 4.2 V. So perhaps the voltage drop is not that important after all...Anyone who have any experience or thoughts about this dilemma? Please let me know!Best Regards

author: Harvs
author_rank: Super Contributor
timestamp: January 15, 2013, 01:17:26 pm
content: By the time you get to the voltage cut out level the current will be much lower than 2.5A. So it will be much less of a concern.However, 2.5A is pretty close to the beads max rating. So why not parallel a couple of the ferrite beads, split the current through them.

author: ConKbot
author_rank: Super Contributor
timestamp: January 15, 2013, 02:11:24 pm
content: Lithium battery charging generally terminates at C/20, so your voltage sag should drop from 43.5 to 2.2 mV when charging is terminated, making the error insignificant compared to the charger accuracy.Depending on how fast youre discharging though (if its though the same lead) it may be worth it to parallel a 2nd ferrite.
Liability of making projects public - Page 1
Forum section: electronics / projects

author: malc-c
author_rank: Newbie
timestamp: May 12, 2018, 10:39:38 pm
content: Hi Guys (and Dave ?)I have been developing various PIC based projects for ages now, most of which are still running in my home. One of those projects started life back in 2009 was a four channel thermostat that controlled the heating elements used in reptile enclosures, and I was urged to make it available as a ready built unit to be sold in the UK. However it never happened as I was concerned over my liability should anything happen. I was informed that to sell it I would need to mark it with the EU CE mark, and to do that needed to have expensive testing done to make sure if conformed with standards such as emissions etc. The main concern was that as it switched 240v ac via SSR's that should something go wrong and there was a loss of the animal, or god forbid a fire, that I personally could be held liable. The advise I was given was that if I had sold the item and made a profit then that is deemed as trading as a sole trader, and thus I would be looked on as being in business and would have to follow the same rules etc as a large manufacture.Anyway, since 2009, I've redesigned the controller three times, and each one has run for a few years each time without any risk to my snakes, or family. I'm confident that the safety controls built in prevent the heater exceeding the 32c set points. I'm now developing my 4th revision and again have received a lot of interest in this from fellow reptile keepers. So this is why I'm here.I would like to receive advise on the pro's and cons of selling just the low voltage controller board which plugs into a Arduno Mega2560 board. I will be releasing the HEX code and full documentation pack with the boards. Anyone who wants one of these would still need to purchase additional hardware such as a TFT screen, 8 way SSR module from e-bay and a suitable PSU to power the mega, and so the final assemble (no soldering required) would be down to the "end user".For the record I'm not looking at making a living from these units, just looking at covering my costs and making a little on top to cover the hundreds of hours spent developing this project.RegardsMalcolm

author: Mr. Scram
author_rank: Super Contributor
timestamp: May 12, 2018, 10:54:09 pm
content: I think offering kits and shifting responsibility from you to the buyer and builder is a common tactic. I believe it's why Ultimaker used to only offer kits.

author: sleemanj
author_rank: Super Contributor
timestamp: May 12, 2018, 11:40:42 pm
content: Probably not entirely legit for sure, but for such low run type of stuff as we are talking about, I would go the (partial) kit form and use something like the CERN Open Hardware Licence (https://www.ohwr.org/documents/294), and ensure that the customer agrees to the licence before paying, the OHL includes liability limitation clauses etc.

author: malc-c
author_rank: Newbie
timestamp: May 13, 2018, 11:32:42 am
content: Thanks guys for the suggestions. More research involved
LiFePO4 Battery Fuel-gauge for a BLE Design - Page 1
Forum section: electronics / projects

author: p4rsley
author_rank: Newbie
timestamp: May 05, 2020, 06:08:03 pm
content: Hi, I'm considering using a (roughly 400-700mAh) AA-sized LiFePO4 lithium iron phosphate battery for a design. I will probably use a fuel gauge to monitor the battery for safety, but I have 2 questions about this design and wanted to get everyone's input.1. if users ignore my instructions to use the provided LiFePO4 battery, and instead they use a plain old AA alkaline battery.. what kind of problems can happen with the fuel gauge? I'm thinking of using one of Texas Instruments' bq-based fuel-gauge solutions, so idk if/how it will even detect that the battery is not the correct chemistry. The other problem would be if they try to charge this AA alkaline battery - and this sounds like a fire hazard.2. there are 2 sides to this design - the remote controller, and the "hub". The hub (powered off a wall adapter) will have a BLE module running at 3.3V, but the remote controller is powered off a battery - as I just described above. For the remote controller side, can I just use the direct battery voltage on the BLE, and not go through a voltage regulator - so the BLE module will get about 3V to 4.2V input? (which is within the acceptable input voltage range of this BLE module - since it can take 1.7-5.5V input). So the question is: what happens when one BLE module runs off 3.3V, and the other paired BLE module runs off 3V to 4.2V? Will it even properly make a connection?Thanks for your input and help.
LiFePO4 cell voltage difference - Page 1
Forum section: electronics / projects

author: ZD
author_rank: Newbie
timestamp: August 18, 2021, 01:25:08 am
content: Hi all,I am currently working on a project that uses a 5S2P 7Ah LiFePO4 battery pack. I have analysed and balance charged the pack with my hobby charger and all the cells measure fairly consistently with a capacity difference between the cells of < 1% between the cells and +/- 2 milliOhm.I have noticed that when I am recharging the pack without a balancer, the voltage difference between the cells starts to increase a lot when it is almost fully charged, sometimes there's a difference of 100 mV between the cells. I know the voltage for LiFe cells changes rapidly at very low and high SOC so is this difference in cell voltages just due to the small capacity differences between the cells?

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 18, 2021, 02:39:56 am
content: You have to do the balancing at a fairly high state of charge for that reason, 3.45-3.55V/cell tends to be a good level to do that.
LiFePo4 Chargers - Page 1
Forum section: electronics / projects

author: cRash1001
author_rank: Contributor
timestamp: March 29, 2023, 06:28:22 am
content: Hi,I need to charge 5 14.4V LiFePo4 batteries in parallel and am l looking for chargers that can be easily mounted and hopefully have access to the Charging Status LEDs.The requirement for the charger are:1. Charging current > 2A2. Indicators to show status -> Charging -> Charged -> Fault3. Easy to Mount -> DIN Rail or Open Frame or anything that can be mountedI have encountered some Deskop / Power Brick type chargers but haven't found chargers that can be mounted inside a box. It would be really helpful if anyone could suggest some good chargers.

author: TruslowPJ
author_rank: Contributor
timestamp: March 29, 2023, 04:26:04 pm
content: I have a Noco genius 5 charger that supports 12V lifepo4 batteries. It comes with a mounting bracket, and the included cable uses battery clamps that attatch using ring terminals, so all you need is a screwdriver to convert from clamps to ring terminals. It is meant more as a jack of all trades charger rather than a dedicated lifepo4 charger, but always auto detects lifepo4 batteries for me somehow so I don't have to set the mode.
Light activated switch circuit - Page 1
Forum section: electronics / projects

author: fixit7
author_rank: Regular Contributor
timestamp: May 14, 2019, 12:49:29 pm
content: While I am waiting for my pot to come in, I thought maybe this might work.I have many of the components that it requires already.https://www.gadgetronicx.com/light-activated-switch-circuit-ldr-ic555/Could it be modified to set off a piezo buzzer in addition to the led?

author: Zero999
author_rank: Super Contributor
timestamp: May 15, 2019, 09:39:17 am
content: Yes, but the buzzer must be a small one: piezoelectric is best. Simply connect it between pin 3 and 0V.

author: fixit7
author_rank: Regular Contributor
timestamp: May 15, 2019, 03:42:38 pm
content: What do you mean by 0 volt?

author: Zero999
author_rank: Super Contributor
timestamp: May 15, 2019, 06:34:31 pm
content: Ground. In this case it's the negative of the battery, where pin 1 is connected, but this isn't always the case for all circuits. See the link below.https://www.physicsforums.com/threads/what-does-0-v-exactly-mean-in-an-electric-circuit-mean.803356/

author: fixit7
author_rank: Regular Contributor
timestamp: May 15, 2019, 08:12:49 pm
content: Quote from: Zero999 on May 15, 2019, 06:34:31 pmThanks.So I would connect pin 3 to the positive lead of buzzer and the negative lead of buzzer would go to ground or negative lead of my power source?

author: Zero999
author_rank: Super Contributor
timestamp: May 15, 2019, 10:14:13 pm
content: Quote from: fixit7 on May 15, 2019, 08:12:49 pmYes.
Light board reaction test - Page 1
Forum section: electronics / projects

author: matters_100
author_rank: Newbie
timestamp: September 28, 2011, 04:17:51 pm
content: Hi,I would like to know the type of led (the intensity) that I will need in order to do a light board reaction test like the batak (www.batak.com) ? I thought it will have to be with a high intensity like the LXHL-MD1D (http://www.luxeonstar.com/Luxeon-Star-LED-Red-Lambertian-44-lm-p/lxhl-md1d.htm) (44 lumens) because I wanted to put a little piece of translucent plastic over it (see the batak) but perhaps it's too high ?Any idea ?Thank you.Matt

author: Trigger
author_rank: Regular Contributor
timestamp: September 28, 2011, 04:28:21 pm
content: It doesn't matter if it's a bit too bright. You can always dim it with PWM.

author: matters_100
author_rank: Newbie
timestamp: September 28, 2011, 06:22:48 pm
content: Thank you for the answer.Of course I can dim it with PWM but that's not exactly the what I wanted. I'll ask it an other way :What is, according to you, the intensity (in lumens for example) of the leds used in the batakwww.batak.com?Thank you.Matt.

author: Psi
author_rank: Super Contributor
timestamp: September 29, 2011, 06:57:49 am
content: Looking at that video I'd say it's probably 100mA of white led or leds.Though it's hard to tell just what might be needed if the device was outside in bright sun light.The only way to know is to buy a few types and see how well they work.If you don't need the full 1watt then you may find it cheaper to use 1-4 50mA high flux piranha leds rather than one 350mA 1W star led.Just make sure you use wide angle leds. They are so much better at illuminating things evenly.Anything over 100deg is fine.If you're looking for places to buy lots of leds for cheap check out these two placeshttp://www.hebeiltd.com.cnhttp://www.besthongkong.comI've used both before without any issues.
Einstein's Light clock - Page 1
Forum section: electronics / projects

author: bennbuilds
author_rank: Newbie
timestamp: March 22, 2014, 06:09:22 am
content: I want to build a couple of Einstein's light clocks. If you are unfamiliar with these they are a common equation used to explain time dilation and relativity. A laser pulse is fired at a mirror and when the beam returns it is detected and fired again immediately.Some quick math said if I make it just a couple feet long (2'-8') then I only need a few hundred mhz between pulses. The quicker the better because I'll have more accuracy if it's different from another clock =DI built a really fast laser (recommendations for a better quick laser are also welcome)and got a fast photo diode sorta-setup. I need some help getting that clock signal down to something more readable via a divider or maybe just a fast adder that stores numbers that big. It would only have to run for a few seconds to get some good data. A bunch of dividers, adders and flip-flops is what i'm thinking.If you have any ideas or products in mind that are sorta cheap and will work I gotta know about it!Thanks, don't steal this yourself!
Light controller legalities and certification - Page 1
Forum section: electronics / projects

author: electron_misfire
author_rank: Contributor
timestamp: November 18, 2014, 07:19:11 am
content: Hi guys,So I'm building a light controller that I hope to sell (it uses a triac dimming circuit) and I'm wondering whether it's legal to sell this without certification and if I do need certification, how to get it cheaply.Sent from my iPhone using Tapatalk

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: November 18, 2014, 07:37:29 am
content: QuoteIf you want to sell it within Australia, No (that was easy).QuoteI don't think it is possible to do it cheaply. The cheapest would be at a wild guess maybe $4000.It would be classified as a declared article and as such needs safety testing.It would also need EMI testing.One testing place should be able to do both lots of tests.First thing you need to do is work out what tests they do exactly and make sure it passes them all even before you even send samples to them.It's called pre-compliance testing.

author: electron_misfire
author_rank: Contributor
timestamp: November 19, 2014, 12:30:55 am
content: Hi, ok I guess I'll have to think about this more. Do you know what standards I'll have to apply for I want to sell this in Australia, the USA and Europe

author: Kjelt
author_rank: Super Contributor
timestamp: November 19, 2014, 09:31:36 am
content: You need to provide more details, I think if you make it DC operated and double isolated (so you have a third party certified external power supply) you have less hassle than if you make it directly mains powered. Is it a mains lighting controller, or a Led lighting DC controller, what is it?Not to ruin your dreams but there are a lot of lighting companies selling controllers out there, are you sure you want to invest in certification without knowing for sure you can at least break even on it?Some companies/certifications I know of: Europe: KemaKeur, TuV USA: ULlook on a global powersupply connector to see what kinds of certifications it has.
Light Meter - Page 1
Forum section: electronics / projects

author: sdmuashr
author_rank: Newbie
timestamp: November 10, 2015, 04:22:05 pm
content: Hi,Has anyone got experience with this circuit?http://circuitswiring.com/bar-graph-light-meter-by-ic-741/The circuit was built but does not work. The LEDs are supposed to turn on one by one as the intensity of light increases on photo-transistor. Can anyone tell me about how to make this work? Also if a two lead photo-transistor were to be used then how it should be connected?The circuit works in Multisim but not in reality! (See the attachment.)Thanks

author: Kleinstein
author_rank: Super Contributor
timestamp: November 10, 2015, 08:11:04 pm
content: The circuit is made for a photodiode, that can provide a output voltage. The phototransistor needs a voltage drop to let a current pass. To make is work the Phototransistor should not go to ground, but with the collector to the positive supply and the emitter to the OPs input / resistor. Due to the higher current the 1 M value might be rather high.The 741 OPs have a current limited output - so the LEDs will likely survive.Today I would tend to use a single Supply OP like TLC271 oder LM358. Then a single 9 V battery is enough, as not negative supply is needed any more.
"Light Multiplier" - "like joule thief" from 2009 -- can someone analyze? - Page 1
Forum section: electronics / projects

author: Undweeber
author_rank: Regular Contributor
timestamp: November 06, 2019, 10:20:15 pm
content: Can someone replicate and analyze what is happening here, why does this still feel like watching magic, the dude took a microwave fan coil, disassembled the core, took the remaining rod from the coil and ended up with an "air core" from what i understood it is wired like a joule thief, but i am not sure how it works without a core, and especially how it transfers energy to a spinning magnet and effectively powers extra 2 LED's..would be nice if Dave replicated this and explained how "joule thief" works or if this video is related, I suspect it is the same sort of thing like that bateroo battery life extender sort of jazz, but this is just a speculation.

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: November 06, 2019, 11:02:44 pm
content: Why didn't he measure theactual power consumption, instead of just asserting that it's somehow only using as much as is required to light one LED? Seems pretty clear that the circuit is pushing a lot of current through that coil.Also the fact that the LEDs in the receiver are surrounded by reflectors makes it more difficult to gauge their brightness by eye.

author: Undweeber
author_rank: Regular Contributor
timestamp: November 06, 2019, 11:18:20 pm
content: im pretty sure those were directional 5mm LED's and the reflectors were just a gimmick like in many chinese toys, doing absolutely nothing when it came to light direction, so judging from that, id say they seem pretty bright
Light Sensitive Design - Page 1
Forum section: electronics / projects

author: rbarkoch
author_rank: Newbie
timestamp: February 09, 2015, 12:08:33 am
content: I just saw over at the Raspberry Pi forums that the new Raspberry Pi 2 may have some crashing issues when it's exposed to a flash from a camera. Is this a type of problem that's been seen before and worth spending extra effort to designing around when designing a circuit/PCB? I've never heard of anything like this before.Forum link:http://www.raspberrypi.org/forums/viewtopic.php?f=28&t=99042

author: edavid
author_rank: Super Contributor
timestamp: February 09, 2015, 03:06:52 am
content: The actual problem chip is said to be an On Semi NCP6343 in CSP.This link (found on Hackaday) explains the problem with CSPs:http://www.silabs.com/Support%20Documents/TechnicalDocs/AN0878.pdf

author: SeanB
author_rank: Super Contributor
timestamp: February 09, 2015, 04:50:09 am
content: Old problem, especially with diodes used for protection in high impedance circuits which would not work with the lid off.
Light up "series" of lights using hand cranked generator? - Page 1
Forum section: electronics / projects

author: corrado33
author_rank: Frequent Contributor
timestamp: September 30, 2016, 06:09:41 pm
content: A friend of a friend wants to light up a series of lights (incandescent) using a hand cranked generator (increasing voltage the harder/faster you crank) sort of like a game. Almost like the hammer games you play at the carnival except you'd be turning the generator yourself.What would be the best way to do this? I could obviously do it with a MCU and relays, but I think that's a bit overkill. What's the discrete way to do this?

author: Tomorokoshi
author_rank: Super Contributor
timestamp: September 30, 2016, 08:41:13 pm
content: How about something like this:http://www.digikey.com/product-detail/en/texas-instruments/LM3914N-1/LM3914N-1-ND/3701307With some perf board and a little bit of analog conditioning it might just work. As the loading of the next light turning on will load down the input signal, there can be a chance for some oscillation to happen when crossing thresholds. Might need some additional filtering or hysteresis for that.

author: flynwill
author_rank: Regular Contributor
timestamp: October 01, 2016, 03:57:26 pm
content: I'd expand on that idea by having the circuit act as a voltage regulating load. Ie add an opamp circuit (probably with relatively low gain) so that the circuit turns on as many lights as necessary to keep the voltage more-or-less constant. The lamp wattage then determines how challenging the game is.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 01, 2016, 04:50:14 pm
content: If you can use fluorescent tubes, you could take a common 4 foot tube, wrap it with a grounded fine wire or mesh, and drive only one end with an AC flyback circuit. You'll get a "thermometer" effect that varies with the applied voltage. Even burned out tubes can be used.

author: EmmanuelFaure
author_rank: Regular Contributor
timestamp: October 01, 2016, 08:54:36 pm
content: Cranking to light up lightbulbs? Oh, that's cuteHave a look from 5'09 :
Lighting LEDs- PWM dimming from a distance? - Page 1
Forum section: electronics / projects

author: GaelZorro
author_rank: Newbie
timestamp: September 11, 2020, 12:10:08 pm
content: Hello All,I'm working an idea here and I'm trying to understand if it would be 1/ feasible and 2/ a good idea: to control 24VDC LEDs and (small) LED strips from 4W to max about 30W, right now I have the PWM dimmers (about 20kHz frequency) right next to the LEDs.My idea would be to move all the PWM dimmers to one location in the switch box. Let's say one big unit, with 24 outputs for max 20 amps total.For the bigger LED strips the PWM dimmers will stay right where they are.The issues as I understand them:1/ deal with the inductance of the wire, about 90µH for maximum 40 meters total round-trip: I can add a flyback diode to the outputs2/ EM radiation from the 40 meters of unshielded wires with about 1 amp and 20kHz frequency through them: that's a total unknown for me. What are the consequences?3/ Voltage drop: that's not an issue, I run the LEDs with 24V and in the worst case scenario the voltage drop is less than 0.5V: 2%, that's fine for me.4/ Maybe other issues that I don't know about?I'm asking because I haven't found a commercial product that does this, so maybe there's a reason?Thanks for any advice!

author: kvet
author_rank: Newbie
timestamp: January 20, 2022, 10:46:39 am
content: @GaelZorro Hi, have you found answers on your questions?

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: January 21, 2022, 09:06:49 am
content: Last year I chatted to a guy whose business makes variable message signs ... the type you might see by the side of the road when there is construction ahead, with a big LED matrix. EMI is a huge problem even in that application where the cable lengths are much shorter. He had some proprietary solution that he didn't go into details on, but this is likely a major reason why you don't see it being done.

author: ajb
author_rank: Super Contributor
timestamp: January 25, 2022, 06:41:30 am
content: Local PWM with a well decoupled power input would be better in terms of EMI, but you have to be realistic about the dI/dt and dV/dt you're throwing around either way. Soft switching the transistors (don't just slam the gate open and closed with a big gate driver at least) can help at the expense of increased power dissipation at the dimmer.As far as the flyback diode goes, remember that the flyback current is equal to the initial current so you don't have to go crazy.
Lighting of a staircase - Page 1
Forum section: electronics / projects

author: gaminn
author_rank: Frequent Contributor
timestamp: October 10, 2019, 01:14:43 pm
content: Hi,I would like to design an ambient lighting for a staircase. I'm even thinking of using it as a main lighting.(This is only an illustrative picture of a staircase)There will be digital LED strips built in handrail. As a man goes along the handrail, the LED strip should light on, the light should move with the man.The question is what sensors to use to detect position of a man to turn on corresponding part of a LED strip? The sensors can be built in handrail, they can be also on walls, whatever. PIR, some proximity sensors, ghz radar?

author: Marco
author_rank: Super Contributor
timestamp: October 10, 2019, 06:07:49 pm
content: Microwave motion sensor modules are really cheap and can be hidden well.

author: FenTiger
author_rank: Regular Contributor
timestamp: October 10, 2019, 06:31:14 pm
content: Security pressure mats?https://cpc.farnell.com/defender-security/pm1-pk/pressure-mat-stair-595x170mm/dp/SR06677If you can afford one per stair, that is, and find a way to hide the wiring somehow.

author: sokoloff
author_rank: Super Contributor
timestamp: October 10, 2019, 06:34:13 pm
content: I think the very last thing you want in a stairwell is quickly and possibly unpredictably changing light levels.I would think an area PIR to light up and entire floor's worth is probably as far as I'd go.If you want to "make it cool", maybe have the LED string chase / fill when initially lighting up and shrink / fade when turning off, but I would be very leery of trying to follow the human closely.

author: vad
author_rank: Frequent Contributor
timestamp: October 10, 2019, 11:16:27 pm
content: Quote from: sokoloff on October 10, 2019, 06:34:13 pmWe have exactly this solution in our office building and I hate it. You step into the darkness and then wonder for few moments whether motion sensor is in working condition. And then, as you move between floors, you continue evaluating responsiveness of every PIR switch or lack of thereof.The best staircase is constantly lit staircase.
Lighting Transformer Enclosures? - Page 1
Forum section: electronics / projects

author: David_AVD
author_rank: Super Contributor
timestamp: July 23, 2014, 04:49:44 am
content: Does anyone know of an OEM source for "lighting transformer" enclosures like the one pictured below?It could have room for connections at either one or both ends.

author: SeanB
author_rank: Super Contributor
timestamp: July 23, 2014, 06:44:24 pm
content: The scrap bin at the local electrical wholesalers?

author: David_AVD
author_rank: Super Contributor
timestamp: July 23, 2014, 09:07:23 pm
content: Not really practical for 100+ units. That's why I mentioned OEM source.If it were only a few I'd gut some full units and sticker over the original text.

author: David_AVD
author_rank: Super Contributor
timestamp: July 24, 2014, 11:20:36 am
content: I foundthis supplier on AliExpresswhile I was looking for a totally different type of enclosure!
Lighting up T5 8W linear  fluorescent lamp - optimum parameters - Page 1
Forum section: electronics / projects

author: e-pirate
author_rank: Regular Contributor
timestamp: September 14, 2014, 11:31:27 am
content: Hi, folks!I'm going to make an UV light box from an old AGFA scanner so I can completely migrate from printer-iron PCB production to negative film photo-resist technology. I've got 8 ? T5 8W "black light" Sylvania lams to place them at the bottom of light box. The main problem - is to fire em up. So, what I'm going to do is to use IR2520 for 2 lams in series (total 4 ballasts required). I use Ballast Designer v4 for initial design, but the problem is that 8W lumps are seem to be not so popular, so I was not able to find several parameters to enter values to the program. What I did - I wrote to Russian devision of Sylvania with a question, but they simply ignored me (which is quite common for Russia, unfortunately).So, does anybody know max. preheat voltage and ignition voltage for this type of lamps? I've found that nominal working voltage is 56V, nominal current is 0.145A and preheat current is 0.22A.

author: e-pirate
author_rank: Regular Contributor
timestamp: September 17, 2014, 06:09:14 am
content: Well, I wrote to England and German devisions of Havells Sylvania and got no respond ether.So, anybody have any ideas?

author: e-pirate
author_rank: Regular Contributor
timestamp: September 19, 2014, 06:29:06 am
content: Oh, well, Russian Government Standard (GOST we call em) 6825-91 has all I need. Folks on other forum pointed me to that paper. The answer is: Max preheat voltage: 11 V, Min ignition voltage is 290 V. Party is over
Lightning cable dummy load - Page 1
Forum section: electronics / projects

author: bborisov567
author_rank: Regular Contributor
timestamp: September 16, 2022, 11:30:10 am
content: I want to compare a bunch of chinese lighting cables. The plan is to put a load at the end and measure the voltage drop of the cable. Seems simple, by looking at the pinout pin 1 is GND and pin 5 is +5v. And indeed without load there are 5 volts but when i connect 180 ohm resistor across the pins the voltage drops to 2.7 volts. It knows that there is no phone connected and it limits the current. My question is how can i trick the cable and have it pass all the current?