hybridfree/eevblog-posts huggingface dataset:
Pond heater - Sanity check my reverse enginering efforts - Page 1
Forum section: electronics / projects

author: freman
author_rank: Contributor
timestamp: June 13, 2023, 06:27:46 am
content: Hey,So I once again come here and humbly request more brain power than I can conjure up on my own.We have this dumb as dirt pond heater that resets itself to 25c after a power outage and has no other method of control - and normally I'm a huge fan of not everything needs wifi but seeing as it's a 500 watt heater and the power pricing is what it is I would like a little more control over it (or at least to have it stay at 20 where we set it so I can use a wifi power switch) either way my intent is to desolder the existing controller and dead bug a replacement (or an esp)I've put some effort into reverse engineering it, it's based around aHT46R065Bmicro and I've traced out what I believe to be the heater/temperature circuits leaving the dual 7 segment led panel for last (cos I might not even need it)I'm 99% sure the I have the hater bit done, it's simply a pin to a resistor to a transistor (or mosfet) to a relay. The bit I'm not sure about is the 3 wire NTCI which has 3 pins NTCI, GND, YellowPA1 and PA0 are also AN1/AN0 (A/D input channels), I've never used a 3 wire NTC before so no idea if that makes sense, it all buzzes out like that...

author: PCB.Wiz
author_rank: Super Contributor
timestamp: June 13, 2023, 08:08:41 am
content: Quote from: freman on June 13, 2023, 06:27:46 amWarm the NTC up and check with a ohm meter, and check the voltages when running too ?Instead of overthinking this, if itisa NTC, why not simply parallel a suitable resistor, so the controller 'thinks' it is 25'C ?

author: freman
author_rank: Contributor
timestamp: June 13, 2023, 10:18:25 am
content: That is not only "oh that's smart" that's "why didn't I think of that" I've watched enough big clive on youtube...Thank you.Not as much control as replacing the mcu but also, just enough control that when the tariff his $6 per kw/h I can turn it off with a wifi switch till the tariff chills out.Next task, figure out how to give the dehumidifier in the shed a similar upgrade (Tho I can't just "shut that off" it needs to cool off for 4 minutes)
Pong on DS1052e and new toolchain for homebrew - Page 1
Forum section: electronics / projects

author: Wartex
author_rank: Frequent Contributor
timestamp: January 01, 2012, 05:12:00 am
content: Check out this guy's youtube profile

author: IanB
author_rank: Super Contributor
timestamp: January 01, 2012, 05:32:50 am
content: Oh no, not another new thread...See here and here:https://www.eevblog.com/forum/index.php?topic=6121.0https://www.eevblog.com/forum/index.php?topic=6113.0

author: PeterG
author_rank: Frequent Contributor
timestamp: January 01, 2012, 06:05:56 am
content: They say things come in threes......LOLRegards
Poor Maker's Infrared Receiver - Page 1
Forum section: electronics / projects

author: AnalysIR
author_rank: Contributor
timestamp: May 28, 2014, 01:58:45 pm
content: Just wanted to share our latest post on the:"Poor Maker's IR Receiver"http://www.analysir.com/blog/2014/05/28/poor-makers-infrared-receiver-2/It describes a method to create your own IR receiver with the following:- 2 resistors- 1 IR Led- 1 ArduinoSouce code is provided, which captures signal timings & modulation frequency.Hopefully, it will be of interest or useful for some!
Poor man's analogue comparator using CMOS gates. - Page 1
Forum section: electronics / projects

author: Zero999
author_rank: Super Contributor
timestamp: February 18, 2011, 09:42:46 pm
content: When responding to the other thread with an idea about using a CMOS gate as a linear amplifier, I remembered an experiment I conducted awhile ago using a couple of gates to make a comparator.https://www.eevblog.com/forum/index.php?topic=2550.msg34540#msg34540I was impressed that it actually worked. Fair enough, the performance wasn't great and the common mode range of the inputs is a volt or so from either rail but it's not bad considering I'm usign an IC not designed to do this. It's probably worth doing if you have a spare couple of logic gates on an IC and don't want to use another for a comparator and is certainly fine for a thermostat using a thermistor or a light sensitive switch with a CdS cell.R1 = R5R2 = R3Hysteresis = Vdd*R1/R4I used the CD4011 but there's no reason why it couldn't be the CD4001 or even a 74HC04.R1 or R2 could also be replace with a potential divider to the powersupply rails, in which case it should be treated as the value of the potential divider resistors in parallel. You can't just replace them with a pot as the output impedance will vary with the pot setting so keep R1 or R2 as is and use a much lower value pot, say 1M and 1k respectively.
Poor man's MSOP soldering - Page 1
Forum section: electronics / projects

author: xchip
author_rank: Regular Contributor
timestamp: June 23, 2013, 01:54:21 pm
content: I went a bit wild yesterday evening...http://codinglab.blogspot.be/2013/06/poor-mans-msop-soldering.htmlEnjoy!

author: Psi
author_rank: Super Contributor
timestamp: June 23, 2013, 02:23:55 pm
content: Another way is to use an IC socket and solder a small length of single core wire into each hole. Then you can bend the wires to match the IC pins and solder the chip in mid-air.It does't look as pretty but its really quick to do.

author: xchip
author_rank: Regular Contributor
timestamp: June 23, 2013, 02:30:24 pm
content: Quote from: Psi on June 23, 2013, 02:23:55 pmAny pics?

author: SeanB
author_rank: Super Contributor
timestamp: June 23, 2013, 03:17:34 pm
content: Nice, must try it some time.

author: Dajgoro
author_rank: Frequent Contributor
timestamp: June 23, 2013, 03:41:22 pm
content: QuoteI used that method a while ago, but it was a miniature bluetooth module. When I was done, I covered the entire thing in epoxy, so I got a nice solid component.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: June 23, 2013, 05:00:20 pm
content: Seems cool ill try it

author: Psi
author_rank: Super Contributor
timestamp: June 24, 2013, 02:40:42 am
content: Quote from: xchip on June 23, 2013, 02:30:24 pmYou only need to get one of the wires connected to the IC and it will stay there while you bend/solder the rest of the wires.I normally solder all of the wires into the socket first and have them a bit too long to start with.

author: Unknown
author_rank: Unknown
timestamp: June 24, 2013, 02:48:35 am
content: Heh, wish this worked for a QFP-100.

author: mariush
author_rank: Super Contributor
timestamp: June 24, 2013, 02:57:12 am
content: Or this ... the solder wire is 0.56mm in diameter

author: xchip
author_rank: Regular Contributor
timestamp: June 25, 2013, 03:08:27 pm
content: Quote from: Psi on June 24, 2013, 02:40:42 amGood stuff, I have to try that!BTW that is a SOP package, the one I was soldering was a micro-SOP, the lead pitch is 0.65 mm, twice as small as the SOP

author: c4757p
author_rank: Super Contributor
timestamp: June 25, 2013, 03:11:13 pm
content: Having tried both methods, I must say I greatly prefer the first - sticking the wires to tape and then cutting them in the middle after soldering. I tend to make a mess out of the second method.
Poor man's active probe made very poorly. - Page 1
Forum section: electronics / projects

author: antenna
author_rank: Frequent Contributor
timestamp: October 07, 2021, 07:17:13 am
content: I gave this poor mans active probe a try.http://elektrotanya.com/files/forum/2009/10/e04a036.pdfI had no new copper board, but was able to cut a piece off another scrap project. Had no toner to print a resist, had to use fingernail paint and apply with a probe tip. Someone made off with the copper chloride etchant I kept in a captain morgan bottle, but I have kitchen supplies. Soon it will get probe tips and stuffed in a copper pipe with a little 12v camera battery.I learned I am HORRIBLE at working with these tiny 0805 and 0603 size things. I can hardly see the pieces on the desk let alone move them around or solder them. There are at least four BF998's lost somewhere in the carpet.

author: Hamelec
author_rank: Regular Contributor
timestamp: October 07, 2021, 07:48:11 am
content: Yes, nice project. There are a lot of information here in the forum about it..It is also available on EBay.BTW: You noted that the PCB board has to be double sided? (for C1 and ground)

author: antenna
author_rank: Frequent Contributor
timestamp: October 07, 2021, 05:09:28 pm
content: Quote from: Hamelec on October 07, 2021, 07:48:11 amYes, it is. There was just enough copper on the other side for a probe pad and a partial ground plane. I'll definitely be redoing this project and probably add another amp stage to the board when I get more stuff ordered. I know they have them on ebay pre-made but thought (incorrectly) that it would be funner this way.
Poor-mans bath bucket assistant  - Page 1
Forum section: electronics / projects

author: dave_j_fan
author_rank: Regular Contributor
timestamp: January 15, 2015, 04:59:03 pm
content: Guys ,sharing a tiny gadget to monitor bath water temperature , it warns with a beep when water is hot enough to take bath--battery powered--hassle free dip and on* will add a water sensing transistor switch to eliminate the on/offimprovements requested /comments /feeback welcomeother possible uses-- baby wetting bed detection--soldering is hot indication-- auto CPU fan high low control and so on .....
Poor wifi until I relocated board (with pics) - Page 1
Forum section: electronics / projects

author: spackard
author_rank: Newbie
timestamp: June 27, 2011, 04:22:19 am
content: I recently bought a tablet PC, found it had very poor WiFi reception, took it apart and found it had a CC&C WF-294 WiFi board double-sided taped to the mainboard. If I lifted it up off the tape it worked fine, laid down it would stop receiving well, could never find a suitable fine adjustment to the original mount that would allow it to work so I relocated the board to an empty spot in the tablet away from other components and it works sufficiently.Pictures:https://picasaweb.google.com/106665950947437882076/UPadZT180GoogleAndroid22FroyoTabletPC7Inch1GHZTabletPCCamera4GBZeniThinkM7013?authkey=Gv1sRgCNjuqpDYy_GdugE&feat=directlinkIf you look closely you can see the designer made the mainboard with a little rectangular hole, presumably for an RF diode to emit RF out of? I'm not sure about the heat or RF issues of this design, so I'm guessing I'm asking if this design is common, and if in your guess is it good, bad, or ugly?In case you want to know, it's a Zenithink ZT-180v2 7" tablet, running Android 2.2.
Poor/non–documented PCBs, kits, etc! - Page 1
Forum section: electronics / projects

author: Chris56000
author_rank: Frequent Contributor
timestamp: April 23, 2018, 09:52:17 pm
content: Hi!I'd like to begin this thread on the subject of an issue that raises many problems, that of PCBs, kits, test–equipment in kit form with no schematic, B.O.M., assembly or instructions for setting–up etc., etc!Post all your examples, and if anyone comes across an original source of documents for something previously unknown, a link can be added to complete the project!A couple of examples of what I mean:–A) The long blue TDA7293 PCB sold all over eBay etc., and not a single component–value posted;B) The "XJW01" LCR Meter Kit sold for £60–75 up until last year in a plastic case, with internal mains power supply, again absolutely NO assembly or setting–up instructions!Chris Williams
Pop and thump sound coming in through speaker when turning the class D ON - Page 1
Forum section: electronics / projects

author: tapasxplore
author_rank: Contributor
timestamp: April 03, 2018, 10:01:46 am
content: Hi,I am using TPA2005D1 class D amplifier IC, whenever I am turning ON the IC, while the volume is set to high, it is making loud thump and pop sound, then it goes away and works fine. But while the volume is set to low and then I turn ON the device, then is no thump and pop sound.The line level input that I am giving to TPA2005D1 contains small DC offset, but I am using coupling capacitor to make offset zero. (Please find the schematic attached below)

author: Zero999
author_rank: Super Contributor
timestamp: April 03, 2018, 10:32:36 am
content: Don't set the volume too high then: problem solved!This is quite common with any audio amplifier, due to the AC coupling capacitors charging up, during power on. You could delay the start up of the amplifier by adding an RC circuit to the shutdown pin, although you might need a Schmitt trigger after (e.g. 74HC1G14) it, to ensure stability.I notice there's no decoupling on the VDD line: add a 1000µF capacitor in parallel with 100nF, as close to the power pins as possible.

author: Brumby
author_rank: Unknown
timestamp: April 03, 2018, 11:07:52 am
content: Some high power amplifiers have relays which disconnect the speakers during the first few seconds after power-up. This works very well for fixed sound reinforcement installations with set microphones.I designed a system a couple of decades ago that had several fixed microphones and others that were plugged in as required. The people using this system were not technical in any sense and giving them basic microphone training was a challenge for some. The mixer was preset and locked for normal use, but an operator could run it live, if they were sufficiently competent.For normal use, the rules were simple: Plug in all the microphones required and then turn on the system. In my testing, I would flick on the switch and duck out to a nearby speaker just in time to hear a short period of silence followed by the system becoming active - and a lowly cricket somewhere near a microphone came through clearly ... without any disruptive transients of any kind.

author: tapasxplore
author_rank: Contributor
timestamp: April 03, 2018, 01:13:40 pm
content: Hi,Method 1:Can we connect 100K resistor between C15 and ground ; 100K between C16 and ground, so that there is no buildup of charge in the capacitor as to reduce the pop sound in the first place.Method 2:We can delay the start of the TPA2005D1 using RC circuit in the shutdown pin, so that pop sound will be eliminated.Should I start with method 1 or method2 ?-Tapas

author: Zero999
author_rank: Super Contributor
timestamp: April 03, 2018, 09:37:23 pm
content: Quote from: tapasxplore on April 03, 2018, 01:13:40 pmHow would that help?QuoteRead my previous post.
Popcorn noise in transistors with how it looks and sounds - Page 1
Forum section: electronics / projects

author: iMo
author_rank: Super Contributor
timestamp: December 15, 2023, 07:10:22 pm
content: Interesting video on popcorn noise in transistors with audio samples..

author: mawyatt
author_rank: Super Contributor
timestamp: December 15, 2023, 07:27:31 pm
content: One of the worst Op-amps for Popcorn Noise were the original BiCMOS RCA type CA3140, and others in that series. They got better over time as the BiCMOS process improved.Remember we had to use select devices way back in 60~70~80s, as many devices had this "feature"!!!Best,

author: EM84
author_rank: Newbie
timestamp: December 25, 2023, 07:37:39 pm
content: What a surprise that you found and liked my video!I was hoping for someone who really has a comprehensive explanation, but no luck so far.But anyway, a few comments are pretty inspiring.

author: Kleinstein
author_rank: Super Contributor
timestamp: December 25, 2023, 07:46:08 pm
content: The circuit used for the tests has multiple noise sources and it not that sure where the popocorn noise is comming from. Besides the transitor there other possible sources: the trimmer/pot to set the base voltage, though here the filter capacitor helps a little and both OP-amps. The 1 M resistor can also contribute quite some noise, though usually not much popcorn noise. Depending on the operation point also the supply regulation can contribute.Some curves show clear random telegraph type noise, but there are also quite a bit of short puleses that a a different source.

author: EM84
author_rank: Newbie
timestamp: December 25, 2023, 09:19:45 pm
content: Sure, the circuit is not perfect, but I once tried a brand new BC817 (SMD) as "quiet reference".* I had to go down to 10nA/div to get a reasonable amplitude of its noise on the screen. For the old "pop corns" typically 50 to 200 nA/div were sufficient to get a nice view. Regarding the supply, the LM317 (outside the cookie tin) as pre-regulator and the LP2951 (inside) should be really quiet, I also played around with LTSpice to see the effect of supply voltage ripple, don't remember the details, but there was no cause for alarm in the results.*) See this video (unlisted but linked in the main video description) for the new SMD BC817 and for an old BC237:https://youtu.be/lkHfqwbG58w

author: djsb
author_rank: Super Contributor
timestamp: December 25, 2023, 09:22:38 pm
content: Are there any specific application notes that cover measuring noise in discrete transistors that I should be aware of? Thanks.

author: sharow
author_rank: Contributor
timestamp: March 21, 2025, 09:41:00 am
content: Hello.Last year, I got bunch of old BJT. So I made test circuit based on this(OP) video.Long story short, here are the results.--About "Noise Scatter Plot"* [A new method for identification of RTS noise]BULLETIN OF THE POLISH ACADEMY OF SCIENCES TECHNICAL SCIENCES Vol. 54, No. 4, 2006https://journals.pan.pl/dlibra/publication/128068/edition/111740/contentEdit: I upload part 2 and 3.I made a playlisthttps://www.youtube.com/playlist?list=PLFvzfCumNo8Q-0to5D6WnQ2GJ2zewqUAh
Populated PCB - ESD / mechanical protective packing - Page 1
Forum section: electronics / projects

author: cio74
author_rank: Regular Contributor
timestamp: April 02, 2015, 12:34:38 am
content: Hello,I have a board with microcontroller, SRAM, FLASH, a CR232 battery, relays along with other components. What would be the best material to use for packaging?I was thinking of the below, please share your opinion:1. PCB board inside a silver/clear moisture barrier ESD bag along with a pack of desiccant and humidity indicator2. Black/pink ESD foam at the bottom of the box. Should that be anti-static, dissipative, conductive?4. ESD foam at the top?3. The above in a cardboard boxThanks.

author: DanielS
author_rank: Frequent Contributor
timestamp: April 02, 2015, 12:48:10 am
content: As long as you use a conductive/dissipative bag for the PCB itself, the rest does not really matter as long as whoever receive the bag grounds himself and the bag before picking it up and opening it.
POR chip that works on 12v reset lines? - Page 1
Forum section: electronics / projects

author: cnt
author_rank: Contributor
timestamp: August 09, 2019, 11:25:20 pm
content: Hi All,There seems to be thousands of open drain sot23 POR chips that hold the reset line low for 10's to 100's of ms on power up. My problem is I'm working with a 12v system and they're all designed for 6v max. Current consumption is not a problem and they only take microamps so I can divide VDD to get in range of their threshold voltage fine, but none of them spec a Vds max for their output FET.Does anyone know of a POR IC that has a open drain output with Vds max>12v?

author: David Hess
author_rank: Super Contributor
timestamp: August 10, 2019, 03:20:25 pm
content: There are some:https://www.analog.com/en/ltc2965But the common solution is to add a common base transistor cascode to the output pin. So the open collector output pulls the emitter/source to ground which pulls the collector/drain to ground but the transistor holds off the high voltage.

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 10, 2019, 03:28:28 pm
content: Well, yeah.Many supervisor/reset ICs come in variants: different output polarity, OD or totem pole...Just select one that has a totem pole output with inverted polarity, and drive a MOSFET with max VDS > 12V. Done.The LTC2965 mentioned by David is interesting if PCB area is at a premium, but otherwise not sure it's worth it compared to the above solution. LTC2965 is not cheap.

author: David Hess
author_rank: Super Contributor
timestamp: August 10, 2019, 04:01:51 pm
content: I only used the LTC2965 as an example. I would do what I suggested and use the POR chip of my choice with a common emitter/source or common base/gate output transistor to provide a high voltage open collector/drain output. With a MOSFET, only a single external part may be required.

author: Yansi
author_rank: Super Contributor
timestamp: August 13, 2019, 08:32:59 pm
content: TL77xx (TL7702, TL7712,...) series chip.More than cheap enough.

author: cnt
author_rank: Contributor
timestamp: August 14, 2019, 09:32:04 pm
content: TL77xx is exactly what i was looking for! Thanks.Thanks to others too. because I asked an overly specific question the other solutions didn't satisfy my constraints, but are much appreciated.

author: temperance
author_rank: Super Contributor
timestamp: August 16, 2019, 11:33:31 pm
content: A common gate connected MOSFET circuit might work. But we don't know your requirements.Gate: connect to POR VCCGate-source: high value resistor. (in order to not load the voltage divider powering the POR)Drain: pull up to 12V, your level shifted copy
Porn Book - Page 1
Forum section: electronics / projects

author: Gersonfb
author_rank: Newbie
timestamp: April 08, 2015, 07:44:04 pm
content: I just got my pornographic book.

author: 4cx10000
author_rank: Regular Contributor
timestamp: April 08, 2015, 08:09:53 pm
content: Me too and the Practical Electronics For Inventors as well, both arrived today. Funny, they came in a blue sack...

author: CM800
author_rank: Frequent Contributor
timestamp: April 08, 2015, 08:14:24 pm
content: Cool, how does it compare to the second edition?

author: Warhawk
author_rank: Frequent Contributor
timestamp: April 08, 2015, 08:28:56 pm
content: Quote from: Gersonfb on April 08, 2015, 07:44:04 pmCongratulation, I am still waiting for mine.By the way, don't you guys want to stick with one thread only ?https://www.eevblog.com/forum/blog/the-art-of-electronics-3rd-edition/https://www.eevblog.com/forum/chat/the-art-of-electronics-3rd-edition-author-response/https://www.eevblog.com/forum/chat/my-review-of-the-art-of-electronics-3rd-edition/and probably others..

author: Macbeth
author_rank: Super Contributor
timestamp: April 08, 2015, 08:41:16 pm
content: Thankfully mine came wrapped in a plain brown paper. The neighbours curtains were twitching. Later her husband was giving me all the nudge, nudge, wink wink about it though. Nods as good as a wink to a blind bat and all that.

author: jlmoon
author_rank: Unknown
timestamp: April 08, 2015, 08:46:27 pm
content: So we should declare this day as "National A.O.E. Book Day" (Title dependent on country)

author: mazurov
author_rank: Frequent Contributor
timestamp: April 08, 2015, 09:27:45 pm
content: Just got mine :-).

author: 4cx10000
author_rank: Regular Contributor
timestamp: April 08, 2015, 09:35:13 pm
content: QuoteWell, I'll have a look at it when it's bed time. Of course I had a quick one but not that much that I can tell what's new. For the price I couldn't resist, bought it from Book Depository and Taoe as well
Port Expander + Driver (74HC595, MCP23017, ULN2003) - Page 1
Forum section: electronics / projects

author: 0xFFF0
author_rank: Regular Contributor
timestamp: October 31, 2022, 12:44:42 am
content: Hi, who knows the current market for port expanders? I am looking for a solution with as little footprint as possible. It would be very good if the outputs could also drive relays so that the ULN2003 driver is no longer needed. Anyone know a good solution?

author: MasterT
author_rank: Frequent Contributor
timestamp: October 31, 2022, 01:20:43 am
content: TPIC6C595 pehaps? Or you can check out Toshiba TBD62xxx - some have SPI inputs, and rest circuits as ULN

author: Ian.M
author_rank: Super Contributor
timestamp: October 31, 2022, 01:27:37 am
content: T.I. do a range of combo 8 bit port expanders + open drain drivers: TPIC6C595 (100mA, 33V), TPIC6B595 (150mA, 50V) and TPIC6A595 (350mA, 50V). The logic side looks like a 74HC595.

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 31, 2022, 01:37:58 am
content: TPL9201, NJW4829

author: 0xFFF0
author_rank: Regular Contributor
timestamp: October 31, 2022, 10:32:30 am
content: Seems perfect!-->TPIC6C595
Portability upgrade - Page 1
Forum section: electronics / projects

author: angelioto007
author_rank: Contributor
timestamp: February 05, 2015, 06:07:44 pm
content: Hello EEVBlog comunity,i have made myself a small little boombox O0, but i have one big problem, it´s not portable!Normally i power it from 9.6V (400mA) mains adapter.Well i have found bunch of NiMH 1,2V 800mAh AAA batteries, so i´ve put together 10 cells to make a 12V rechargable battery pack.Now, i want to charge it, but in such an automatizated way, so i don´t have to build something like a 14hrs timer or someting like that. but i want to have that charger clever, so it will stop charging the batteries when they are fully charged. i also want to implement in the boombox undercharge protection, but dunno how to do it(i will accept a uController like ATtiny,but i would prefer classic analog circuitry)...And yes, i did make something (https://www.eevblog.com/forum/projects/battery-protection-circuit-i-had-to-try-it/msg573805/#msg573805), that looks like it would work, but i have kinda forgotten about it and it´s done in a complicated way. I don´t need all of the protection that i´ve made in the old schematics...Thx anyone for their suggestions and ideas

author: lutkeveld
author_rank: Regular Contributor
timestamp: February 05, 2015, 09:22:21 pm
content: I would go with a 3S lithium pack. Low price and charging/protection circuits are everywhere.It's much smaller and higher capacity. 800mAh is nothing, what amplifier are you using?

author: angelioto007
author_rank: Contributor
timestamp: February 06, 2015, 03:15:47 pm
content: Quote from: lutkeveld on February 05, 2015, 09:22:21 pmi have 10 of the batteries in series, which gives me 8000mAh in total. I´m using TDA1517, 6W is good enough, altough the IC is nowadays rare.

author: rdl
author_rank: Super Contributor
timestamp: February 06, 2015, 03:47:36 pm
content: No, in series the mAh doesn't add up. Each cell contributes it's voltage at it's rated milliamp-hours. You get 10 times 1.2 volts at a total of 800 mAh. To increase the milliamp-hours you have to wire in parallel.

author: angelioto007
author_rank: Contributor
timestamp: February 06, 2015, 08:46:30 pm
content: Quote from: rdl on February 06, 2015, 03:47:36 pmi thought it would? anyway, thx for correction, lerned something new
Portable 12v LiPo supply. Bypassing the battery. - Page 1
Forum section: electronics / projects

author: dumle29
author_rank: Regular Contributor
timestamp: March 29, 2014, 02:41:12 am
content: Hey there. So I'm build a portable LiPo pack for a 12v supply. I have everything figured out except one thing.I have built it up like so:LiPo charge board -> battery -> battery protection board -> boost converter.When I hook up the LiPo charger board to usb, I want to take the 5v and run that directly to the boost converter, bypassing the battery, and I therefor need some sort of circtuit to disconnect the battery.I've drawn up this, and want to know if this would work. If it's stupid, and if theres any better way.-MikkelQuick sketch:Eagle schematic:

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 29, 2014, 02:46:56 am
content: Turn the MOSFET around to avoid a sneak path and use a Schottky diode to reduce the voltage drop. The MOSFET must also have a threshold voltage well below that of the minimum battery voltage.

author: dumle29
author_rank: Regular Contributor
timestamp: March 29, 2014, 02:51:59 am
content: If I turn the fet around, wouldn't the parasitic diode mean that the battery and thereby charger would be connected to the boost converter all the time?

author: dumle29
author_rank: Regular Contributor
timestamp: March 29, 2014, 02:57:02 am
content: actually thinking about it there would be a .8v reverse biasing the internal parsitic diode (battery at 4.2v) so I guess that should be fine, and yeah will go with a schottky

author: sleemanj
author_rank: Super Contributor
timestamp: March 29, 2014, 08:35:55 am
content: https://www.eevblog.com/forum/projects/primary-(eg-usb)-and-auxillary-(eg-battery)-power-steering-ic/msg299942/#msg299942Edit to add: the circuit I made in that thread didn't *quite* work, close but not close enough. I was going to try using a logic IC to see if I could improve it, but havn't got around to it yet.

author: dumle29
author_rank: Regular Contributor
timestamp: March 29, 2014, 02:38:46 pm
content: So looking at schottkys, what would I be looking for in terms of reverse current? I'll be charging the battery at 1000 mAMy local store has 6 available:MBR1060 | 0.1 - 15mA reverse current1N5822 | 0.5 - 20mA reverse currentMBR2545CT | 0.2 - 40mA reverse currentMBR3045PT | 1 - 100mA reverse currentSB360 | 0.5 - 10mA reverse currentSB550 | 0.5 - 25mA reverse current
Portable AC Power Supply for Testing - Page 1
Forum section: electronics / projects

author: DonEduardo
author_rank: Newbie
timestamp: January 23, 2015, 02:08:15 pm
content: I put together a buck regulator and a 12v to 110v AC inverter to convert my underutilized 18v Ryobi drill batteries to a portable AC power source for testing things on the bench. It could also be used as emergency power for small devices in a pinch. I housed the thing in a broken Ryobi battery charger casing. It's worked out great for me so I thought I'd share the idea. Here's a link to the video describing it in more detail:http://youtu.be/UAl8MGOWlw0
Portable Battary Bank - Page 1
Forum section: electronics / projects

author: QuantumKnight
author_rank: Newbie
timestamp: December 26, 2013, 04:37:25 pm
content: Good day all,Note I am still new to this and most of my project are still with the 555 chip, but I am wanting to design and build my own usb power charger to use for portable electronics. I was hoping for someone to point me in the right direction to learn about the process from a simple breadboard circuit and then I can move on from there. I want to be able to charge the battery from an external source and then be able to charge from the battary using a usb port. If anyone can provide me a starting point for this project or simple circuits to build that will help me understand the process that I can later put it all together, it would be greatly appreciated. Thank you and have a nice day.

author: Jon86
author_rank: Frequent Contributor
timestamp: December 26, 2013, 04:43:57 pm
content: If you want to build the charger from simple jellybean chips, then good luck. Someone else can help you with thatOtherwise, using a battery charger IC it's very simple. Look at what TI or any other manufacturer has available, and use the example circuit on the datasheet. The chips tend to be in SO packages, but you can just get a cheap DIP adapter and solder it on, they're very simple chips to use.I'm assuming you want to use Li-ion batteries?

author: QuantumKnight
author_rank: Newbie
timestamp: December 26, 2013, 05:29:48 pm
content: Thank you Jon for you replyYes I am wanting to use Li-ion, I will look at battery charger IC as you suggested. My next question should be should I choose the IC on the input and output power or an IC that deals with thermal regulation to prevent the battary from getting too hot? Thank you again.

author: Jon86
author_rank: Frequent Contributor
timestamp: December 26, 2013, 07:03:10 pm
content: Thermal regulation is important in some commercial products, but it's not really necessary at all in your project.You probably want to choose an IC that has an output current of 1A or less, that almost guarantees that your battery will not get too hot.
Portable Battery Powered Desktop: How do I charge it? - Page 1
Forum section: electronics / projects

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: August 02, 2016, 03:44:58 am
content: So I am building a battery powered desktop PC. I have run trial runs on it already and the lithium batteries have no problems running it. I am using six 9Ah lithium cells in series with (I think) a 2C discharge rate. Currently, I just have two 3 cell BMSs taking care of cell protection. Not ideal as you can't charge the batteries in series, because when one set reaches a full charge, the other one gets cut off from charging as well, same issue happens when discharging, and I don't want to run into issues with that...So this got me thinking. Even if I were to buy a 6 cell BMS that can do moderately high current (peaks of >5A) how would I charge it? I know lithium cells are best charged fairly slowly. But! This "laptop" will very likely be used while plugged in, and I expect the system to draw over 100W at full load, meaning I would need a charger pushing out at least 100W. And if I do have poorly balanced cells, I fear that some cheaper BMSs might not be able to properly balance them at these higher charge rates. I have seen enough 3rd party macbook batteries...Any ideas? My best guess would be to find some sort of PSU with an arduino hackable output current, and just try to limit the charge current, raising it as the PC draws more power.For those wondering, the PC has an i3 4350T and a GTX 650 with a 19in 720P LCD.
Portable bench PSU with switch pre-regulator - Page 1
Forum section: electronics / projects

author: hbozyq
author_rank: Contributor
timestamp: September 27, 2023, 01:13:43 pm
content: I want a bench PSU and want to build it on my own.Here's some spec that I want:1. compact: I got no much free space on my dormitory desk.2. wide input voltage range: 12-24v, can be powered by laptop adapter, PD charger, li-ion packs or etc.3. relative high power: 0-25V, 0-5A, 50-100w output power.4. decent noise and stability: <30mv ripple? I got no good idea now. But it won't be rocket scicence anyway.5. Low cost: Jellybean part should be used so anyone can build one (no LT parts).So I think switch regulator should be used, for a voltage greater than input is needed. I decide to try some 4 SW buck-boost controller. It's now common in PD powerbank.And a linear post-regulator is needed for lower noise and fast CC/CV operate.I start this thread to record my tries so somebody may learn something and hope some kind people pointed out my mistakes.For now I have already done the linear post-regulator schematic. Every compoment can be found in lcsc. Any feed back will be welcome.

author: hbozyq
author_rank: Contributor
timestamp: September 27, 2023, 01:23:44 pm
content: For the pre-reg, now I find PL5501. It looks promising, 36V max output and >95% effcient. I wiil give it a try.
Portable LED board project - Page 1
Forum section: electronics / projects

author: cosmicray
author_rank: Frequent Contributor
timestamp: November 22, 2024, 01:57:50 pm
content: This is a relatively simple LEDs on a board project. The eventual usage may be multiple, in different applications. The board is 100mm x 100mm. Everything was hand soldered.The 2835 LED chips are Cree JK2835 "X series" and are binned for 18.0-18.5 volt ratings, but I'm running down the curve, in the 15.5 volt area. Specific part number (for this reel) is JK2835AWT-0-6GB-J20-FV-U-02. The LEDs are rated at 1 watt, but I'm running them well below that threshold, closer to 1.5 mW each. Down rating the power results in a heat dissipation that is negligible. The LEDs are believed to contain six emitters (probably 3V) wired in series.The board is divided into two regions (left and right) with a LM317LZ regulator controlling each half (operating as a 2-terminal constant current device). Total current for both halves is 109-110 mA. That current is consistent until the voltage source drops somewhere below 17 volts, at which point they begin to subtly dim. Using a new fresh Ryobi 18V 2 AHr pack, I was able to run that board for 19 hours at full brightness, then 2 more hours as they began to dim. At the conclusion the measured input voltage was near 16.4 volts. The fuel level on the front of the Ryobi pack, when checked, would flash the left most light (indicating it was quite low).Each side of the board is divided into 25 sub-circuits, one 43Ω resistor and two JK2835 LEDs. That protects the failure of one LED (either short or open circuit) from taking down the entire side. If both LEDs go open circuit, then slightly more current is available to the remaining sub-circuits. The design is trying to envision most failure scenarios, and to fail gracefully.The green module, on top of the Ryobi power pack, was found on eBay. It is sold to allow the 18V power packs to run Hot Wheels toy cars. It comes with an on/off switch, pigtails, and fuse holder. The provided fuse is 30A, but I replaced them with a 3A (which was the lowest I can find locally). The connectors are Anderson Power Poles, but I used pink/lavender to differentiate the 18V from the usual 12V red/black.The image with the power turned on has a bit of paper over the lights, because otherwise it was swamping the camera on my phone.The first use of this board, once I have a suitable housing, is to mount two of them on the outriggers on my recumbent trike, so I can have better visibility during the pre-dawn hours.Hope this gives people here, some food for thought, about what is possible.
Portable solar powered power bank - Page 1
Forum section: electronics / projects

author: Baxxxter
author_rank: Newbie
timestamp: November 28, 2017, 06:20:33 pm
content: Hi,the reason I am posting this here is this not an assignment given to me, this is a project I chose to do as my degrees final year project.Abstract:I am going to design and build a portable solar powered device which is able to charge a USB device and drive a 4w fan. It also includes lithium ion batteries to store energy in case the direct illumination is not present.Objectives:*Portable ( foldable pv panel)*Efficient ( combination of MPPT and PMW)*keep the fan running in full speed and charge USB devices at the same time.(Ideally)* Prevent the battery from getting over-charged and over-discharged.*Satisfy USB devices charging specifications.(assuming be able to charge a mobile phones 3500mah battery within 1 hours in full illumination)*relatively low cost.I would appreciate it if you guys help me to find out where should I start in calculating . what steps should I take. what information's do I need. Components have to carefully calculated so u have to keep assumption minimal. In the end of the day this is a device that I eventually need to build and it has to work.P.S: attached a diagram of the system.

author: robermeyer
author_rank: Newbie
timestamp: December 02, 2017, 10:54:11 pm
content: You should provide some more requirements of the system.battery voltageFan voltageFan currentThis would decide buck or boost for 5volt usb. Buck is more efficient.What size battery is in system?Why MPPT to charge a battery and drive fan? Excess solar is going where?Normally you would take solar and generate 5v for USB.Any excess is wasted.
Portable Soldering Station - Page 1
Forum section: electronics / projects

author: Isad
author_rank: Frequent Contributor
timestamp: January 10, 2016, 07:17:59 pm
content: Hello all.I needed to build this pice for somthing i need to do portable and couldnt take a full solderign station.I used a atmega 328p with the arduino bootloder,16x2 lcd and a lmc662 and the code well i didnt have thetime for it so i got 1 off the internet it worked with some tweaks.The temp wich is display on the lcd is5 deggres C wich in my case isnt a big case.I have to thanks Hight Voltage for sending the ersa i-tooland yes i did butcher the irone since it didnt have a regullar heater sensor pinout on the leads and i dint havethe original pinout so i drilled a hole through the handle its not pretty.This has its flaws since i didnt put a on/offswitch and its a bit more bulkier then i wanted since its a 2 board construction and the xlr plug is prob a over kill it worksof 7-24V(or 32V but idk thats safe on a ersa handle) and it can output a rough amount of 100W with a 6 cell lipo you get about 1h to 2h(or more i havent tested anything but just making asumption since it draws about 4A when on full load on a 24V).I am thinking ofmaking a custom pcb wich would be les bulkier.Thanks for taking your time to read this.
Portable Voltmeter Ammeter Wattmeter - Page 1
Forum section: electronics / projects

author: Long Technical
author_rank: Newbie
timestamp: May 23, 2018, 01:38:06 pm
content: https://youtu.be/SyJnyot4flkIn this video i had show you Portable Voltmeter Ammeter Wattmeter with Rechargeable Battery Insite All of thing we need in there. Please check on description and do step by step you will get Portable Voltmeter Ammeter WattmeterThe firts we need to make PCB. I use eagle software for design shematic and PCB. After that i order the PCB by upload gerber file toJLCPCB.COMand after 2 day i reieved 10PCB high quality with only 2$. You can try like my by upload gerber file toJLCPCB.COMfor get PCB online. Or you can make PCB by yourselft by download the PDF file at end of topic.look at some picture from my project, and check more video at my youtube channelhttps://www.youtube.com/channel/UC0dW_Q1nhPqbUQZvbeogOnQ/videos
Portus and Haywood stereo decoder schematic sanity check-Help please. - Page 1
Forum section: electronics / projects

author: djsb
author_rank: Super Contributor
timestamp: March 03, 2021, 09:04:13 pm
content: I have 2 schematics for a stereo decoder. The first one is produced by the original designers in 1970. The second one is an improved version from 1978. There is one point on the second schematic that says "Link to B or C" on the newer 2nd schematic that I don't understand. Ambiguity drives me mad where schematics are concerned as when I make a schematic I try VERY hard to avoid confusion. I am on the process of making a schematic in MicroCap 12 and KiCad and I have an actual physical circuit that is working (a built kit from the late 70's) so ultimately I can check that. Just want to ask what people reckon this part of the circuit (marked with the text in quotes) is ACTUALLY connected to.Physically checking it on the PCB is going to take a lot of disconnecting of wires. Drawing the circuit with pencil and paper would be quicker. Thanks.

author: Renate
author_rank: Super Contributor
timestamp: March 04, 2021, 12:20:39 am
content: On the second schematic:Directly under "Link to B or C" is a line that has nothing to do with this, it bypasses it all despite having an ink blob/slash.The white dot under that is what they mean.That is the DC bias for the L & R outputs.Using (A, B, C) 12 V, 6V, 0V, connect it to C, ground.Using (A, B, C) +6 V 0 V, -6 V. connect it to B, ground.

author: djsb
author_rank: Super Contributor
timestamp: March 04, 2021, 09:24:46 am
content: Thanks Renate.David.
Positive ground plane design  - Page 1
Forum section: electronics / projects

author: turbo!
author_rank: Regular Contributor
timestamp: May 09, 2014, 12:18:09 am
content: This scale uses a negative tip AC adapter ( I hate those) and I noticed that the entire board ground is positive. It was designed to have an optional RS232C interface.I am guessing it is using a design like this? Any idea why else ?

author: rs20
author_rank: Super Contributor
timestamp: May 09, 2014, 12:25:02 am
content: It's perfectly valid (and common in multi-layer boards) to have ground planes and power planes. The choice is largely arbitrary, many people ascribe too much magical significance to the ground rail when it's just an agreed-upon reference point.The AC adapter will have an isolated output, so there's no different between a ring-grounded negative supply and a tip-grounded positive supply. Look at the RS-232 port ground, what is it connected to?I don't understand the schematic at all.

author: turbo!
author_rank: Regular Contributor
timestamp: May 09, 2014, 01:58:11 am
content: Quote from: rs20 on May 09, 2014, 12:25:02 amThis instrument is NOT marked with polarity and a standard adapter will fit and destroy parts.Same can be said about which pins on connector are used for what. People place too much significance on using 2/3 for Rx/Tx. Why not just wire it to pins 5 and 8, then use 5-15R for 480v as well as 120V? Conventionally, positive tip is the norm.I've seen many double sided boards where one side is Vss and the other is Vcc. Both planes are bonded to positive input of power source on this board and the logic level stuff gets its 5v from -5 source (-5v with respect to plane).QuoteThere is no port. It's an optional feature that this one didn't come with. Fixed a few things on the schematic. What I am guessing is that the layout is so that logic Vcc is used as signal ground for 232c, and TxD is connected to system ground. So, it rests at +5.0v, but pulls to the tip side of AC adapter to get -5 to 8v to swing for mark signal.

author: rs20
author_rank: Super Contributor
timestamp: May 09, 2014, 03:45:40 am
content: Quote from: turbo! on May 09, 2014, 01:58:11 amOK, help me out here. Whenever a circuit has a negative supply, the negative nets are drawn below the ground nets. So your schematic should have a battery symbol the correct way up, ground symbols up the top of the diagram. Once I flip it the right way up in my head, it looks vaguely legitimate. TxD will flip between ground and aroundabout -5V (even if Vin is significantly different, like -10V, the transistor won't be able to turn on that far). But that's not a larger swing than the chip is capable of outputting itself. I'm not sure where you're proposing that this 8 volts is coming from. And I don't know what SG is.