hybridfree/eevblog-posts huggingface dataset:
basic transistor question - Page 1
Forum section: electronics / beginners

author: stevieg
author_rank: Newbie
timestamp: February 28, 2013, 05:38:10 pm
content: i need to control a 2 wire idle control motor with a negative pwm signal coming from an ecu going through a transistor what do i need PNP or NPN and how sould it be connected? i will most likely be controlling the negative side but can control the positive side if necessary .if it helps its a haltech sprint 500 ecu using a vw golf mk3 throttle bodythanks Steve
Basic troubleshooting for no sound from Digital Media Receiver in car. - Page 1
Forum section: electronics / beginners

author: jbclem
author_rank: Newbie
timestamp: October 27, 2023, 11:46:34 am
content: I have Bravo View IND-100u digital media receiver, hooked up with an old Blaupundt amplifier (BPA 230B 2x30watts bridgeable) and one speaker. It turns on but there is no sound.The receiver turns on, the display acts normally...I can change radio stations, volume, mode (radio, aux, sd card/flash drive). The amplifier power light goes on, but no pops, clicks, or other sounds that I would sometimes hear when I pull the rca cables off and on or turn the receiver off and on.I replaced the RCA cables(receiver to amp) with new, and switched the speaker with it's new unused twin. Still no sound. I don't have a spare amplifier that I trust so I can't switch amps.I'd like to isolate the problem and I want to check the output from the receiver, and also the output from the amplifier. I have a DVOM but I'm not sure what I would be measuring and if my DVOM is the right instrument. I need some very basic troubleshooting help as a starting point.

author: CountChocula
author_rank: Unknown
timestamp: October 27, 2023, 08:40:43 pm
content: If you have another sound source that you know is working (like, say, your smartphone, or a portable CD/MP3 player), connect it to the amplifier; if sounds comes out, the problem is in the receiver, and if not, the amplifier is on the fritz (or perhaps not connected correctly). Troubleshooting from there gets a little more complex, depending on where the problem is.As a side note, why both the receiver and amplifier? Fromthe manual,it looks like the receiver itself can already put 20W into 4 external speakers.

author: jbclem
author_rank: Newbie
timestamp: November 01, 2023, 09:23:48 am
content: Thanks for the help. I didn't remember that this unit had a built in amplifier...I installed it 5 years ago to replace one that was connected to the Blaupundt amp so I connected it the same way and didn't think past that since the old school Blaupundt amplifier sounded great.When I disconnected the Blaupundt amp, and hooked up directly to the speaker,..the unit worked. So now I'd like to see if the amplifier can be repaired. I'll start a new thread about that.
Basic wall wart AC question - Page 1
Forum section: electronics / beginners

author: sweesiong78
author_rank: Contributor
timestamp: September 27, 2014, 02:04:40 am
content: Why is it when I stick just one probe of my multimeter into the pin of a plugged in wall wart I can detect the 60Hz signal on my multimeter? how is the multimeter able to complete the circuit?

author: Psi
author_rank: Super Contributor
timestamp: September 27, 2014, 02:10:08 am
content: The single connection provides a AC cycle reference between your meter and the mains making it easier for the meter to pickup 60Hz RF noise in the air around you. At least, that is how it was explained to me. Because it's AC, mains gets transmitted into the air.

author: David Hess
author_rank: Super Contributor
timestamp: September 27, 2014, 03:37:18 am
content: Capacitive coupling into the other multimeter lead generally from earth ground can provide enough signal into the 10 Mohm and roughly 200 picofarad input impedance of the multimeter.This is not recommended but if you hold one lead in your hand, you can use the other to tell the difference between hot and neutral or ground.

author: kolbep
author_rank: Frequent Contributor
timestamp: September 27, 2014, 04:16:29 am
content: If you do hold the other probe in your hand, double check that your dmm is not on resistance or current ranges #Ouch#Lfmf

author: German_EE
author_rank: Super Contributor
timestamp: September 27, 2014, 08:23:15 am
content: I suspect that it is 50/60Hz fields. If I switch my bench DVM to 0,3VAC then I get a varying signal of about 0,15V with nothing attached and 0,26V with the leads plugged in but not connected at the other end.
Basic Zener circuit variation - Page 1
Forum section: electronics / beginners

author: oxcart
author_rank: Contributor
timestamp: October 11, 2015, 07:34:43 pm
content: Hello again!I'm using what I've just learned is a linear voltage regulator using a Zener diode. I'll use it to cut off excess spikes from a 6V DC/DC regulator powering a 1A servo.But since I'm caring about power consumption, I was thinking of modifying the basic circuit from this:to this:(please excuse the crudity of this model, I didn't have time to build it to scale or to paint it)So that resistor R is dissipating power only when V>VZ..does this work? Have i overlooked something?

author: sleemanj
author_rank: Super Contributor
timestamp: October 11, 2015, 08:38:31 pm
content: The high voltage is still present at your load because in your drawing the load is across the supply which is giving this high voltage in the first place. For the zener to be useful to you, you need your load to be across it.

author: Wim_L
author_rank: Regular Contributor
timestamp: October 11, 2015, 08:53:02 pm
content: And even if you add an additional resistor in series with the source, regulation will be poor, as the voltage across the combination of a zener plus resistor will be greater than the zener voltage alone, when current is passing through.

author: nuno
author_rank: Frequent Contributor
timestamp: October 11, 2015, 10:45:11 pm
content: I sometimes put a 100uF or so cap right at the plug where the servo connects to the board.If I have sensitive stuff on the same supply, I do the series diode + parallel cap "trick" on the sensitive stuff's positive power rail.

author: oxcart
author_rank: Contributor
timestamp: October 12, 2015, 08:52:13 am
content: Quote from: sleemanj on October 11, 2015, 08:38:31 pmOk, so the the first drawing(wikipedia) does a better job at cutting spikes than mine?

author: oxcart
author_rank: Contributor
timestamp: October 12, 2015, 08:57:00 am
content: Quote from: Wim_L on October 11, 2015, 08:53:02 pmI am assuming my regulator(pololu) does a decent 6V output(5,978V pretty stable), I just want to cut spikes to avoid frying the servo, as 6V is the servo's limit.So, how would you draw it? Or is a Zener a poor idea?

author: Paul Price
author_rank: Super Contributor
timestamp: October 12, 2015, 10:17:01 am
content: The servo you are using probably would be able to handle transient voltages much higher than 6V that it is rated at. Applying voltages more than 6V to this servo for a long time could cause it to overheat and fail, especially if it is operating in a higher than room temperature environment.Conclusion: you don't need the zener diode for protection of your servo at all if your power supply is regulated.
Basics of Op Amp Gain*Bandwidth product and Slew Rate Limits - Page 1
Forum section: electronics / beginners

author: w2aew
author_rank: Super Contributor
timestamp: September 17, 2014, 12:47:24 am
content: This topic has been on my "to-do" list for a long time, and has been requested several times. So, here it is - the basics of an op amp's gain-bandwidth product and slew rate limit. The video gives a basic definition and provides some measurement examples on the bench.Enjoy!

author: ConKbot
author_rank: Super Contributor
timestamp: September 17, 2014, 01:34:53 am
content: Definitely been bitten by this one before! Have a pretty fast signal to gain up and buffer, GBW is ok for the signal & gain settings, but scope it and its a triangle wave. Think about it for a few seconds. "SHIT. SLEW RATE" Then run off and go looking for other op-amps.

author: robrenz
author_rank: Super Contributor
timestamp: September 17, 2014, 01:41:05 am
content: Excellent as always Allan

author: rfbroadband
author_rank: Unknown
timestamp: September 17, 2014, 02:09:34 am
content: good video!

author: rakesh
author_rank: Unknown
timestamp: September 17, 2014, 08:54:55 am
content: thank you for the video alan
Bass (low frequency) sound detection? - Page 1
Forum section: electronics / beginners

author: jorenca
author_rank: Contributor
timestamp: August 09, 2016, 08:43:19 pm
content: Hi forum,I'm trying to build a simple LED bracelet that would light up when (very loud) ambient music haslots of bass in it (for example, when the beat 'drops').However, I encountered the problem where the microphones in my junk bin are all 'telephone' grade ones -that meaning with a small bandwidth, most likely outside the range of 20-200Hz.I started wondering if I could use some reed switch to register the sound, but it seems reed switcheshave a resonant frequency of about 8kHz.Can you propose a sensor to be used, seeking maximum simplicity and low energy consumption?(you may have guessed that I'm building a glowing party bracelet and the overall size is the main limiting factor)Thanks!

author: scanlime
author_rank: Newbie
timestamp: August 09, 2016, 09:34:58 pm
content: Maybe a place to start would be designing a mechanical circuit that has a resonance peak near the range you're interested in? You'll want something with a large surface area that can be sensitive to bass vibrations, without being affected by body motion.If you can create a mechanical surface that's sensitive enough to the bass, you may be able to pick up those vibrations with piezo.

author: Zero999
author_rank: Super Contributor
timestamp: August 09, 2016, 09:51:02 pm
content: Use an electrect microphone capsule which should be fairly sensitive to bass.

author: Brumby
author_rank: Unknown
timestamp: August 09, 2016, 11:11:59 pm
content: ... and a low pass filter ... etc.

author: Audioguru
author_rank: Super Contributor
timestamp: August 10, 2016, 02:22:20 am
content: Here is the frequency response of an ordinary electret mic. It goes lower than 20Hz but the graph stops at 25Hz. A cheap one measures a little different at high frequencies.
BAT85 V BAT85S diodes, any difference? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: August 30, 2013, 12:24:01 pm
content: I have a circuit that calls for BAT85 diodes, and I have a pack of new BAT85S diodes, can I use them? I have looked at spec sheets and see no obvious difference, but presumably there must be *some* difference between a BAT85 and a BAT85S?Thanks.

author: c4757p
author_rank: Super Contributor
timestamp: August 30, 2013, 12:30:43 pm
content: BAT85 is in the very slightly shorter DO-34 package rather than the more common DO-35. I'd say they are perfectly interchangeable unless they've specifically designed the very, very tight PCB for the shorter DO-34 package. (Doubtful, as they could just use a freaking SMD package...)
battery - Page 1
Forum section: electronics / beginners

author: abdullahseba
author_rank: Frequent Contributor
timestamp: March 18, 2014, 01:16:35 pm
content: why do some battery's state that you should not connect them in parallel

author: Torrentula
author_rank: Regular Contributor
timestamp: March 18, 2014, 01:20:49 pm
content: The batteries might not discharge all evenly/at the same rate because of the internal/ionic resistance or aren't charged all exactly to the same level when you buy them, hence when you connect them up in parallel you one battery will 'attempt' to charge the other battery if it's not at the same cell voltage.So the non rechargeable primary cells tell you not to connect them in parallel.Dave did a video on battery ionic resistance:

author: abdullahseba
author_rank: Frequent Contributor
timestamp: March 18, 2014, 01:26:20 pm
content: Quote from: Torrentula on March 18, 2014, 01:20:49 pmit was a rechargeable form the rs catalogue

author: IanB
author_rank: Super Contributor
timestamp: March 18, 2014, 02:08:32 pm
content: NiMH rechargeable batteries should not be connected in parallel for charging if using a fast/smart charger. Parallel NiMH cells are not self balancing and there will be a tendency for one battery to take more current than the other. The result at best will be uneven charging, at worst battery damage.
Battery and charging solution - Page 1
Forum section: electronics / beginners

author: BinaryBits
author_rank: Contributor
timestamp: December 08, 2021, 11:44:37 am
content: So I have this LCR-T4 component tester that is driven by a 9V battery, I have printed a case for it and don't want to open it up every time the battery is depleted.So what solutions are there to install a battery and a charging module instead of the currently used 9V battery?Since usually the charging modules are only up to 4.2V, I need a 8-9V solution.The physical size of the battery/batteries would need to be maximum the size of a single 18650 battery. And it would need to be a rechargeable solution.Thanks in advance.

author: Kim Christensen
author_rank: Super Contributor
timestamp: December 08, 2021, 05:57:46 pm
content: There's a thread about these testers on this blog. Here's a link to a post of someone doing exactly what you want. See their Thingiverse link:https://www.eevblog.com/forum/testgear/show-us-your-$20-transistor-tester-enclosures-and-mods/msg1155862/#msg1155862Another option is to buy one of those rechargeable lithium 9V batteries that have a usb plug on the side and then cut a small hole in the case to access it.

author: BinaryBits
author_rank: Contributor
timestamp: January 11, 2022, 12:26:52 pm
content: Thanks for your answer. Yeah i also thought about the USB chargeable 9V batteries after I wrote the post. Only downside is they are ridiculously expensive, couldn't find them for less than like 25 USD....for a 9V battery.I will check out the link you provided.

author: tunk
author_rank: Super Contributor
timestamp: January 11, 2022, 02:54:59 pm
content: I've been using one of these together with an old, recycledli-po cell. But, it is constantly discharged - either a high celldischarge rate or through the module.https://www.ebay.com/itm/114720734980?hash=item1ab5e37f04:g:oKoAAOSwf3pgSD1i
Battery Backed SRAM Circuit - Logic Questions - Page 1
Forum section: electronics / beginners

author: grantb5
author_rank: Regular Contributor
timestamp: December 12, 2017, 07:25:17 pm
content: Hi, I am doing a simple SRAM expansion on alegacy8-bit micro circuit. The circuit now uses a socketed SRAM and there is a coin cell backup for it.I am adding a small board that pops in the SRAM socket and bank switches a larger SRAM using physical SPST or SPDT switch(es). My worry is current drain when system power is off and the coin cell is retaining the memory. The bank switching is done by raising or lowering the highest order address line(s). When power is off I don't want to drain the coin cell because of bad circuit design. Here is the basic idea, I hope it is clear:Code:.------U-------+5v---. Vmem---| Vcc| || |< |< 1k | SRAM< || SPDT |/--------| Axx (highest addr line)| || |< |< 10k |<||=== GND=Originally I thought tying the high side of the switch to Vmem that drives the SRAM. On second thought, standard +5v seems smarter. I don't want to "energize" that SRAM address line when 5vDC is off. The resistor values are to-be-determined. I just don't want to draw more current than needed to attain the H and L logic levels."Vmem" is a diode combination of the coin cell and the +5vDC standard power supply voltage (whichever voltage is higher drives the SRAM). Only the SRAM and a few gates are attached to Vmem.Or would it be better to tie it to some actual gate output? I do have access to an unused 4011 gate that could be involved. This gate is powered by Vmem also.
Battery backup for router/modem etc. - Page 1
Forum section: electronics / beginners

author: girishso
author_rank: Newbie
timestamp: January 11, 2016, 09:15:54 am
content: Ok.I am looking to build uninterrupted battery backup to power the router, modem, raspberry pi etc.Both my router and modem use a 12v 1A power supply, I am sure they don't need 1A current to function. Planning to use sealed lead acid 12v 7Ah battery.Think I have two options..Option 1: Will the attached battery charger circuit suffice my need?http://www.myra-simon.com/bike/charger.htmlOption 2: Or can I use any battery charger available in the market, and draw power directly from the battery with the charger connected? will it provide uninterrupted supply in case of power failure?Thanks in advance!Girish

author: fubar.gr
author_rank: Unknown
timestamp: January 11, 2016, 09:41:15 am
content: There are 13.7 Volt plug packs available, specifically for float charging lead acid batteries.You can simply connect that in parallel with the 12V 7Ah battery and then to the router.When the AC power is on, the plug pack charges the battery and powers the router. When AC power is off the battery powers the router.Don't worry about the extra 1.7 Volts, routers use DC to DC converters and can handle a wide range of input voltages.

author: girishso
author_rank: Newbie
timestamp: January 12, 2016, 04:59:41 am
content: Thanks @fubar.gr!That's much simpler!!I happened to have ordered a Lithium charger from Aliexpress, it allows setting charge current/voltage, also the float charging current. I hope there is no harm in using this charger for charging the sealed lead acid battery. (http://www.aliexpress.com/item/5A-Lithium-Charger-CV-CC-buck-Step-down-Power-Supply-Module-LED-Driver-New/32580191958.html)Thanks again!
Battery bank - Page 1
Forum section: electronics / beginners

author: nicksydney
author_rank: Regular Contributor
timestamp: November 11, 2016, 01:33:35 pm
content: Hi,I want to make a DIY battery bank for my Nexus 7 tablet. Bought few 18650 battery and was thinking of wiring them up as shown in the picture. Can you tell me whether I'm doing it the right way ?Another thing also I want to be able to recharge the battery so looking around found this boardhttps://www.aliexpress.com/item/3-Serial-12A-Charging-Protection-Board-For-Polymer-Lithium-Battery-12V-Short-Circuit-Protection/32738039954.html.In terms of recharging the battery can I hook the + and - directly into this PCBThanks

author: danadak
author_rank: Super Contributor
timestamp: November 11, 2016, 03:21:48 pm
content: I think you need to take a deeper look at this problem, especially from a safety / fire hazard point of view.http://www.atmel.com/images/doc2599.pdfhttps://media.blackhat.com/bh-us-11/Miller/BH_US_11_Miller_Battery_Firmware_Public_WP.pdfRegards, Dana.

author: nicksydney
author_rank: Regular Contributor
timestamp: November 13, 2016, 12:33:50 pm
content: Found a good video tutorial on how to do itThanks
Battery Capacity Measurement  - Page 1
Forum section: electronics / beginners

author: navneeta
author_rank: Newbie
timestamp: December 19, 2014, 03:30:19 pm
content: Hi, guys I am trying to measure the capacity of a 480 mAH battery. For this I am using constant current measurement method. The test setup is attached(first attachment). Its the same as provided by one of Dave's video. But the problem is I dont get the same capacity as obtained by the battery manufacturer. Their test report is also enclosed(second attachment). Please let me know if I am going wrong somewhere.Also, I want to measure variation internal resistance of battery with temperature. Could someone suggest an effective way to measure it as well.Thanks,

author: Simon
author_rank: Unknown
timestamp: December 19, 2014, 03:50:22 pm
content: So is your capacity more or less ? how old is the battery ?

author: navneeta
author_rank: Newbie
timestamp: December 19, 2014, 04:06:12 pm
content: I measure it to be approximately 380 mAH. Actually I couldn't note the point when the battery voltage reached cut-off point. When I measured last, it had already discharged to 0.9 V. But in the report provided by manufacturer, the battery voltage is 2.0 V at 95.2 hours while in my case its 0.9 V already after 88.25 hours.The battery is very new.Its handmade by the company now.

author: Simon
author_rank: Unknown
timestamp: December 19, 2014, 04:12:03 pm
content: Are you using the same discharge current the manufacturers tests did ? A larger discharge current will give you a lower overall capacity. Battery ratings are supposed to be for a 10 hour discharge, the Ahr rating means that a 10A battery will last 10 hours if you draw 1A from it, if you draw 5A it will not last 2 hours.
Battery capacity tester - Page 1
Forum section: electronics / beginners

author: electron_misfire
author_rank: Contributor
timestamp: October 16, 2014, 08:27:58 am
content: Hi all,I'm working on a project to test different batteries and their capacities.I was thinking of just doing a simple circuit consisting of a resistor and a switch.My concern is basically that it's just too simple. Does anyone have any improvements? Any tips or suggestions?Oh and I already know if battery data sheets, I want to do it myself.Thanks

author: Artlav
author_rank: Frequent Contributor
timestamp: October 16, 2014, 10:33:15 am
content: Not much complexity required - battery, load, N_fet for low voltage cut-off, AVR or arduino's ADC to log data.Watch out for connections - a little contact resistance can go a long way at skewing up the results.Quality breadboards are adequate to get 5% accuracy, but a proper PCB would be more precise and require less maintenance.Chinese battery sockets look almost the same as good ones, but good ones give consistent contact resistance, while chinese ones give random ones.Beware of chargers (NiMH related), they can charge to various levels each time, instead of full:https://www.eevblog.com/forum/projects/battery-capacity-measurement-gives-wildly-varied-results/
battery charger 1.0 - Page 1
Forum section: electronics / beginners

author: J4e8a16n
author_rank: Regular Contributor
timestamp: June 23, 2017, 03:37:49 pm
content: Hi everyone,I am trying to figure out why there is no current in resistor R5.R9 should not be there.The asc file work after you pressed escape. (another bug)The idea is to make a simple pulsed current charger from the one ( I built it and it works fine.) found on the web.Thanks for your attention.JPD

author: matseng
author_rank: Frequent Contributor
timestamp: June 23, 2017, 03:46:49 pm
content: Issnt R5 shorted out by having grounds at both sides?

author: J4e8a16n
author_rank: Regular Contributor
timestamp: June 23, 2017, 06:37:39 pm
content: I corrected this. It was not shorted.It seems the battery counteract the LM317. It does not seems to be rechargeable..I found a rechargeable battery but I dont know how to wire it.
battery charger 120-220   50-60Hz     for laptop, telephone etc - Page 1
Forum section: electronics / beginners

author: J4e8a16n
author_rank: Regular Contributor
timestamp: February 24, 2016, 10:59:06 am
content: Hi,Battery charger 120-220, 50-60Hz from Samsung, Toshiba, etc., for laptop, telephone, etc. How true, good are they?Is there tutorials on this subject?What would be a good 220-120 volts adapter for voyagers.For example:http://www.amazon.ca/Goldsource%C2%AE-STU-200-Voltage-Transformer-Converter/dp/B0022TMB9A/ref=pd_cp_23_2?ie=UTF8&refRID=09HBZEQCJ7QVF620GC16Thanks for your attention,JPD
Battery charger convertion help - Page 1
Forum section: electronics / beginners

author: Glacier55
author_rank: Newbie
timestamp: January 01, 2021, 11:30:08 pm
content: Hello,Can you help me with this problem i have. Because i have a few of this boards laying around ( boards from drill chargers) i want to use them as a power supply for something else.My problem is that board doesnt output power unless battery is connected to it. Because i am a begginer i dont know what i have to do to have a steady output for powering something else. Do i have to short one of 4 wires togeather, or attach some resister do act as a load,... If you can help me i would appriciate it very much.Thank youHappy new year 2021 to everyone.

author: bob91343
author_rank: Super Contributor
timestamp: January 02, 2021, 02:50:19 am
content: To attempt an intelligent answer to your query would require a schematic diagram. Can you trace the parts and create one?

author: Krisby
author_rank: Contributor
timestamp: January 02, 2021, 06:10:56 am
content: As far as I can figure out, these chargers are expecting to detect a voltage when a battery is connected to them. If the voltage is too low, then the charger will indicate a fault, and if the voltage is high, the charger will indicate that the battery is fully charged. If the voltage is in between low and high, then it will start to charge the battery. So, why not connect an adjustable power supply to the charging terminals (get the polarity right), and see if the charger will respond with different voltages? If the charger switches to outputting power when it has detected the right voltage, then perhaps you can put a small DC to DC power supply on the board, so that it can provide the voltage to the terminals that are required to get the charger to output power.If, what I have said above is wrong, then go ahead and try shorting resistance across the charger's output terminals. I would test the resistance of a battery that is neither low nor high, and then put a resistor with that value from one charger terminal to the other.

author: ledtester
author_rank: Super Contributor
timestamp: January 02, 2021, 07:23:52 am
content: Quote from: bob91343 on January 02, 2021, 02:50:19 amIn particular, the black boxy thing on the RHS of the second pic looks like a relay and may be central to how power is delivered to the battery.This, of course, is just pure supposition, but it's probably where I would start the analysis.

author: Glacier55
author_rank: Newbie
timestamp: January 02, 2021, 09:49:31 am
content: Thank you for your help some very interesting ideas. I will play with it today a little bit and try your suggestions. I dont have schematics for it and couldnt find one online also.Thank you all for your time and help.Have a nice day

author: CJay
author_rank: Super Contributor
timestamp: January 02, 2021, 10:23:08 am
content: I suspect there's quite a few more components on the underside of that PCB as well
Battery Charger-Diference Between SLA, NiCad, NiHm and Lithium-ion - Page 1
Forum section: electronics / beginners

author: Greate
author_rank: Contributor
timestamp: May 02, 2012, 03:16:00 pm
content: Beginners Question.What is the difference between the battery chargers of Lead Acid, Nickle Cadmium, Nickle Hydride and Lithium-ion rechargeable batteries? Is it the voltage level? Current? or Pulse?Thanks!

author: IanB
author_rank: Super Contributor
timestamp: May 02, 2012, 03:19:45 pm
content: It's the charging algorithms.You can read all about it and more atBattery Universityand other online resources.Every kind of cell is a different chemical system and responds differently to charging. Control of the rate of charging and detection of when charging should finish depends uniquely on the specific type of cell or battery. (A battery is a group of one or more cells connected together, usually in series. Sometimes charging batteries is a bit more complicated than charging individual cells.)

author: pullin-gs
author_rank: Regular Contributor
timestamp: May 03, 2012, 01:16:52 pm
content: Important note:Never ever try to charge a battery on a charger not designed for it.Especially lithium batteries....very bad things can happen.
Battery charger discharging batteries  - Page 1
Forum section: electronics / beginners

author: B000134
author_rank: Newbie
timestamp: August 26, 2015, 01:07:49 pm
content: H all,It holiday time and recently I have come across a strange issue with some Friwo li-ion 4 cell battery chargers used in my products.The products they are used in are air sampling pumps used to monitor asbestos during removal works. Which up until now have had no problems (besides the usual it fell of a scaffold). However, recently I had a small batch of these returned after a customer returned from several weeks holiday. Upon their return they turned tried to re-charge the pumps and discovered that the batteries had been fully discharged and the charger refusing to charge the battery (as a safety feature).After much head scratching it appears that before they went on holiday the pumps were used and already completely discharged. They were then connected to the battery chargers but turned off at the wall to save electricity. Then the battery charger itself seems to have discharged the battery (over a few weeks).When I first received these pumps I tested the standby current after the low voltage protection had cut in at 13.6V and it was approximately 1uA so no issues there. However, when I connect the charger whilst it is switched off it discharges the battery with 2mA of current.I thought this would be an easy fix and fitted a diode to prevent the battery from discharging however now the chargers wont charge because they cant see a battery.Strangely when I tested good old fashioned linear chargers there wasn't this issue. I wonder if anybody has any ideas or suggestions on how to prevent this discharge without at the same time using power from the battery?Many thanks Chris

author: max666
author_rank: Frequent Contributor
timestamp: August 26, 2015, 04:11:21 pm
content: You can put in a diode, but you have to move the battery voltage sense pin after the diode. (Some attention may also be required to check how the current sensing is done, but shouldn't be an issue probably)However all of this would require to open that Friwo charger and mess around on the existing PCB.

author: B000134
author_rank: Newbie
timestamp: August 26, 2015, 05:40:34 pm
content: Yeah I had a feeling I might have to get my hammer out for those Friwo chargers.Strangely in the datasheet I can't find any reference to exactly how much current is drawn when the power is turned off however it does state at the bottom "There could be abnormal conditions under which the battery connected to the charger feeds current back." I guess I fell for the trap.http://www.friwo-shop.de/documents/1826003_15_2272_500_00_001736_422016196914468.pdfSo I think my next move is to try another type of charger. I just ordered one of these...http://www.mascot.no/admin/common/getimg.asp?FileID=1211The datasheet states "leakage current from battery with mains turned off ? 0" I will try it once it arrives and see what happens.
Battery charger upgrade Help - Page 1
Forum section: electronics / beginners

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: May 03, 2013, 01:28:18 pm
content: I found this charger and I would like to change features of the itemhttp://www.apogeekits.com/PDF_Files/Battery_Charger_Manual_K8012.pdfThe plans upgrade but not sure if it's going to work and would like some help or input1-Use a power brick instead of a transformer2-Increase charging amp from 1 amp to 3 to 5 amp3-Add a voltage and amp display with a 9v battery supplying to it4 Use Soft latch configuration instead of toggle switchesSo what do you guys think

author: Recyclojunk64
author_rank: Contributor
timestamp: May 03, 2013, 03:38:25 pm
content: 1 Yeah no problems here I'd think2 A bigger T7 and lower values in set R29-31 (one third less maybe? Also higher wattage of course) might just do the trick, although I haven't taken a proper look over the schematic though3 Is there a reason you want to isolate their power sources though?4 SW2 would probably require a fair bit of mucking around, maybe a FET for SW1? I always thought those nice resounding mechanical toggle switches are usually the preferred option to cheap plastic clicky things though...

author: Recyclojunk64
author_rank: Contributor
timestamp: May 03, 2013, 04:08:29 pm
content: Probably require a bit of work, but you could quite likely modify the power brick to do all the work for you if you wanted to hack it somewhat. Perhaps you could tap into the feed back circuit in there and give it some constant current control with a comparator ( and a minimalist amount of other stuff)May be worth a think about if your into that sort of thing anyway, otherwise your upgrade should do
Battery charger with current limit help needed - Page 1
Forum section: electronics / beginners

author: Meche
author_rank: Newbie
timestamp: July 11, 2017, 04:36:51 pm
content: Hello!I've done alot of research but I have not found anything for an good solution. I am trying to build a battery charger where you can change the current flowing to the battery. Like an benchpower supply where you change the current limit.The spec is that the battery needs 2 A to charge and it is not good to provide it with more than 2A.So basicly i would like to change the Current limit let say from 1A to 4 A more or less like the imax b6 charger.I know that there is different LM350 and such but I dont want to waste a lot of energy in heat. Could someone send me in the right direction to solve this problem?Best regards

author: vealmike
author_rank: Regular Contributor
timestamp: July 12, 2017, 11:47:32 am
content: What type of battery are you wanting to charge?How do you intend to change the current?Take a look at the Bq24725a. It's a Li-ion smart charger from Texas. You talk to it over I2C and tell it how much current / what voltage to supply.If the cell voltage is lower than the requested charger voltage, then the charger chip provides a constant current charge. If the cell (terminal) voltage equals the requested charger voltage then the charger provides a constant voltage charge until the charge current drops below the termination threshold.For li-ion you must provide your own cell temperature monitoring and software based charge time out. These are safety features and mustn't be overlooked. Cells must have their own protection circuit.Any good?
BATTERY CHARGER/DISCHARGER - Page 1
Forum section: electronics / beginners

author: kezzab94
author_rank: Newbie
timestamp: April 15, 2015, 02:04:29 pm
content: Ive been in electronics about 6 months, im still at collegeI have been asked by work as a projects to build a battery charger/discharger and monitoring system.So far, i have a rough constant current charge and discharge circuit, using an op amp and a push pull transistorthe batteries are to be connected in series so that the same charge/discharge current can go trough them all at the same time, but how do i switch each individual cell out when its charged or discharged?and how do i monitor the voltage of each cell individually?thanks

author: Simon
author_rank: Unknown
timestamp: April 15, 2015, 02:24:41 pm
content: you need to treat them individually, you can't put them in series and expect to manage them individually.

author: kezzab94
author_rank: Newbie
timestamp: April 15, 2015, 02:41:46 pm
content: so do i need to have them in series and in parallel?

author: Simon
author_rank: Unknown
timestamp: April 15, 2015, 02:43:34 pm
content: Neither! but sort of parallel, you cannot connect the batteries together at both ends if you want to monitor them separately, otherwise your just monitoring the whole lot multiple times.

author: bookaboo
author_rank: Frequent Contributor
timestamp: April 15, 2015, 02:48:57 pm
content: Simon is right but you are going to have to be much more specific about what you are trying to do. Are the batteries normally connected in parallel? Whats the battery chemistry? Capacity? Load? Charge/discharge current?

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: April 15, 2015, 03:22:06 pm
content: Lost of missing info , take for example a 12v car battery , a 12v car battery is 6 2.2v cells in series to make 12.75 fully charged battery .If there is a bad cell , there are a few ways to test each cell either by the chemistry - a specific gravity test , or electrically - a cell shorter it loads cells individually .Back in the old days - when car batteries had tar separating each cell , we would use the above to find bad cell and desolder & replace the bad cell .In newer days , use a hot knife to cut the top of the plastic case & do the same .
Battery Charging - Page 1
Forum section: electronics / beginners

author: Polybus
author_rank: Contributor
timestamp: September 08, 2016, 08:07:40 am
content: HowdyI've just bought myself a SkyRC Model RS16 Battery Charger and Power Supply - I am trying to charge NiMH cells/batteries with it.Just to test it out, I attached a single AA NiMH cell rated at 3000mAh (or so it claims) and set it to the NiMH program and set it charging.I set the charge current to maximum of 3.0A, but in the default NiMH programs there is nowhere to set the voltage.When the cell starts charging - I can see the display showing a charge current heading up to about 2.4A, but the Voltage goes was up to over 7 volts - that can't be right can it?? Obviously the cell nominal voltage is 1.2V - so why would it be charging it at over 7 volts - maybe I have forgotten to set something???There are user programmable modes - and in their I can set the NiMH to 1 cell, which shows as 1.2V, but again, as soon as I begin charging - the voltage goes up to 7volts or more.Am I worried over nothing (I'm sure the battery charger knows more than me about this) or am I just not setting this thing up correctly?Cheers.

author: jeroen79
author_rank: Frequent Contributor
timestamp: September 08, 2016, 08:54:06 am
content: AFAIK NiMH is always charged in constant current mode with no constant voltage phase following.Charge termination is then determined by time or by detecting that the battery is full by sensing a drop in voltage or sudden rise in temperature.What does your charger's manual say about that?7V does seem high though.Does the cell get really hot?

author: Polybus
author_rank: Contributor
timestamp: September 08, 2016, 09:09:37 am
content: Its gets hot alright!!!When I start the charge program I can watch the Charge Current ease up to the Max Charge Current (I did have it set at 3A, but now reduced it to 1.2A) and over that same period the Voltage edges up to over 7 Volts.I think I had best leave this thing alone until I better understand what's going on

author: amyk
author_rank: Super Contributor
timestamp: September 08, 2016, 10:44:15 am
content: NiMH is charged with constant current so your charger is trying to force the current to 3A by raising the voltage as high as it can. A 1C charge is extremely fast ,and especially if the cell isn't actually 3Ah but less, explains why the charger is having trouble with getting that much current through it; the chemical reactions that take place when charging can only go so fast. Also, numerous other references I've found on the Internet suggest that the absolute maximum voltage should be 1.8V/cell...Try charging with 0.5C (1.5A), I think the voltage will be a lot lower. I can't easily find any graph of charging voltage vs. current for NiMH but I bet it looks like a gradual slope upwards until the C rating of the cell at which point it shoots up extremely steeply.
Battery choice - Page 1
Forum section: electronics / beginners

author: thjnikke
author_rank: Newbie
timestamp: March 18, 2015, 08:36:43 pm
content: Hello everyone,I have an electric circuit that consume around 180mA, I can choose for an AA battery 1.2V/1300mAh or a lithium ion battery 3.6V/2400mAh.The circuit works on 3.3V and it should last about 1 week. My question is what battery suits best for this circuit?Thanks in advance.

author: JohnnyBerg
author_rank: Frequent Contributor
timestamp: March 18, 2015, 08:41:37 pm
content: Lithium: 2400mAh / 180mA = 13,3 hrs3x AA in series : 1300mAh / 180 = 7,2 hrsIf you want to run for a week: none of the above

author: sacherjj
author_rank: Frequent Contributor
timestamp: March 18, 2015, 09:53:03 pm
content: To get the run time you are wanting, you will have to introduce sleep states (if it is a microcontroller based system.)Does something have to be done continuously, or can you do things in short spurts? This could be short spurts a few times a second or seconds apart.These days, 180 mA is a lot of power for most primary battery powered devices.1 week = just over 30 Ah battery. That is huge. A large cell for a tablet might be 3-4 Ah.

author: Rick Law
author_rank: Super Contributor
timestamp: March 19, 2015, 01:42:12 am
content: Get a car battery or better yet, the marine battery (ie:deep discharge). Even the ones for small cars can be 50AH.Assume you just regulate it down to 3.3V,50AH = 50000mAH @ 180mA => 277.8 hours = 11.57daysIf you buck it down to 3.3V using DC-DC converter, you can easily double or close to 3X that. A 50AH battery will run it for a month.

author: Falcon69
author_rank: Super Contributor
timestamp: March 19, 2015, 02:36:08 am
content: Here's a 6volt one that is 36AhThat's 36000/180=8.33 days. But, when used with a voltage regulator to 3.3v, i was assume you could get around 12-14 days out of it. Plus, it is deep cycle, fairly small for it's power output, and can be charged over and over again. It has no memory on it like other batteries.I'm not sure what you are doing, but for me, I was thinking about getting it to run a time lapse camera for a jobsite, and have a small solar cell to trickle charge it.

author: thjnikke
author_rank: Newbie
timestamp: March 19, 2015, 05:09:56 pm
content: Thank you all, I will look at it!
Battery Connector - Page 1
Forum section: electronics / beginners

author: deemak
author_rank: Newbie
timestamp: November 14, 2022, 06:21:23 pm
content: Hi i’m Mikael from Paris (France),Iv’e got an e-bike battery that doesn’t work anymore. I’ve buyed a battery with standard connector and was thinking to adapt the output to the box where i was pluging my old battery since the bike controller is in the box.I’m searching everywhere for the connector asking some shops that are telling me there are m20 or m25 connectors but when i take mesurments it isn’t the same iv’e got on my old battery, it seem’s to be near GX20 but it is also not exactly the same.I’m totally lost on this if somebody can help a newbie that is sorry for is poor English (i’m French)The battery is the female connector i need. The plastic part with 2 pins holes has a diameter of 12mm, pins holes are 4mm, the internal diameter is something like 19mm….

author: sapien
author_rank: Contributor
timestamp: November 14, 2022, 07:17:42 pm
content: https://nl.aliexpress.com/item/1005003765093346.html?spm=a2g0o.detail.1000060.1.5ffcc346NpFvr0&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.291025.0&scm_id=1007.13339.291025.0&scm-url=1007.13339.291025.0&pvid=d7f86205-ae2e-442c-a18b-0797a12ea569&_t=gps-id%3ApcDetailBottomMoreThisSeller%2Cscm-url%3A1007.13339.291025.0%2Cpvid%3Ad7f86205-ae2e-442c-a18b-0797a12ea569%2Ctpp_buckets%3A668%232846%238112%231997&pdp_ext_f=%7B%22sku_id%22%3A%2212000027093430059%22%2C%22sceneId%22%3A%223339%22%7D&pdp_npi=2%40dis%21EUR%210.87%210.78%21%21%21%21%21%400b0a23b116684534220646208ef979%2112000027093430059%21rec&gatewayAdapt=glo2nldIs this not what you're looking for?

author: deemak
author_rank: Newbie
timestamp: November 14, 2022, 08:29:36 pm
content: Thank you for the fast answer i was thinking about gx20 too but was not sure cause it seems that the pins aren’t as close as on mine, i will upload the other side Picture since i was thinking the two was already uploaded on the first post. The picture of this answer is the connector i need.I want to try to not dismount this one, since its glued and i want to try to fix this battery pack later, i had boost it using a laboratory power supply the power check on light on now, but the original charger doesn’t charge it but that’s another problems i will fix when iv’e got time to do it and also i want to use a standard battery pack i’ve just buy waiting the repairing of the original one and after that at the end i can use the 2 battery’s packs.
Battery contact springs soldered to PCB - Page 1
Forum section: electronics / beginners

author: Purduephotog
author_rank: Regular Contributor
timestamp: December 15, 2020, 03:06:11 pm
content: I have an old amplifier I fixed for a coworker (now 3 years) unfinished because part of the battery compartment was so corroded. And Also I Am A Bad Person.I'd like to finish so need to etch/create a new PCB for the battery contacts. Previously it used a weird spring, but wasn't so much soldered as it was pushed through the hole to hold it. They corroded off, and so did all of the traces.I have the image to work from, but what is the best way to solder a spring? I have some 'copper' ones from higher powered flash lights, and I thought about making a disk with a small trace leading from it for the thru-hole insertion of the power wire. Then I could plop a big chunk of solder down onto the copper where the spring rests and allow that to hold it in place.Trying to do the toner transfer with acetone but I may just end up using a sharpie to draw it. I'm having trouble learning new ideas lately since a stroke.Thanks for advice on soldering springs.

author: Zeyneb
author_rank: Regular Contributor
timestamp: December 15, 2020, 05:29:36 pm
content: Good battery springs are usually made from spring steel and that is hard to solder. Maybe you can mount it to the PCB with an small screw and nut, in combination with a spring washer to maintain good electrical connection. Another option is a product like Digikey 36-5201-ND, this has a solder lug. But I don't know if you can properly fit this into that battery compartment.Apart from the technical aspect I think it is important to keep your motivation up as you mention things aren't going so well for you. Specifically I'd encourage you to strive for a good professional result to put a nice green check mark on this repair task.Good luck!

author: Benta
author_rank: Super Contributor
timestamp: December 15, 2020, 06:42:43 pm
content: A solder joint under continuous mechanical stress will always fail, whether in a year or in five years is impossible to say.You should look for a way to fix the spring mechanically and not just through the solder joint.Suitable material is phosphor-bronze. I wouldn't select steel.

author: Ian.M
author_rank: Super Contributor
timestamp: December 15, 2020, 07:05:56 pm
content: See my comments on flash plating steel with copper to make it solderable here:https://www.eevblog.com/forum/beginners/soldering-to-strange-metal-contacts/msg3315024/#msg3315024However, Benta is right - the solder *MUST* *NOT* be on or directly adjacent to a part of the spring that flexes and must not carry a high mechanical load on its own, otherwise failure is a certainty.