hybridfree/eevblog-posts huggingface dataset:
Bidirectional current sense IC - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: June 29, 2015, 05:32:13 pm
content: 1. I need to select bidrectional current sense to be used as ammeter.2. Going through some of voltage output IC , to be operated at 3.3V.3. Since it is ammeter it can high side or low sense or between two loads.4. Only problem I have found that IC have miminum CMR, e.g 4V. So I need to have minimum voltage of source to measure current. E.g if I have 1V source & load is 100ohm, I won't be able to measure current through it.5. Best I can found is LMP8601 from TI.6. Any suggestions on that.

author: PSR B1257
author_rank: Frequent Contributor
timestamp: June 29, 2015, 06:57:58 pm
content: http://www.allegromicro.com/en/Products/Current-Sensor-ICs/Zero-To-Fifty-Amp-Integrated-Conductor-Sensor-ICs.aspxP.S.: Please write in sentences. Every time these stupid numeration...

author: PICmonster
author_rank: Regular Contributor
timestamp: June 30, 2015, 01:57:36 pm
content: Diodes Inc (formally Zetex) do a range of current sensor devices, I don't know the particular but maybe it's worth a look?http://www.diodes.com/?q=search&type=0&value=current%20senseDo you have a block diagram showing your requirement with Voltages and Currents etc, then maybe I can assist further
Bidirectional duplex level translators - Page 1
Forum section: electronics / beginners

author: brainwash
author_rank: Frequent Contributor
timestamp: August 06, 2013, 10:55:01 pm
content: I'm looking to replace some level translators (3.3 to 5V) or buffers with a full-duplex solution. Was not sure these existed and I don't even know how to search for them, basically something without a direction pin is needed.The only one I was able to find was Texas InstrumentsADG3304. Are there any other equivalents, perhaps accepting a higher voltage on the second side?

author: notsob
author_rank: Frequent Contributor
timestamp: August 06, 2013, 11:27:17 pm
content: Same voltages but 8 channel is Texas TXS0108E

author: andyturk
author_rank: Frequent Contributor
timestamp: August 07, 2013, 01:42:55 am
content: I used one of thosehere.

author: brainwash
author_rank: Frequent Contributor
timestamp: August 07, 2013, 01:49:34 am
content: Thank you.Are there any parts that are not from TI?Ironically, it's faster for me to sample from TI and receive them almost overnight, for free, than it is to order something from a distributor.

author: brainwash
author_rank: Frequent Contributor
timestamp: August 07, 2013, 03:38:39 pm
content: I just found out the magic phrase to do a google search: "level translator without direction pin" or "level translator with auto direction sensing"ST2149,2129,2349,2329,2189ADG3300NVT2008-2010PCA9306NLSX3012,3014,4014FX[L/M]A101,102,104,108MAX3394-3396ISL3034-3036EDS G3401TX[B/S]0101,0102,0302,0104,0304,0106,0108NTB010,0104UM3308PI4ULS5V102,104,201,202; PI4ULS3V08,PI4ULS3V16....

author: bingo600
author_rank: Super Contributor
timestamp: August 08, 2013, 04:39:48 pm
content: This TI Guide just landed in my mailbox - TI's Translation Guidehttp://links.mkt102.com/ctt?kn=108&ms=NDIyNTcyNTkS1&r=ODM5MTgwMTI5NwS2&b=0&j=MTk3NzY3NTcxS0&mt=1&rt=0Directhttp://www.ti.com/lit/scyb018/Bingo
big capacitor question - Page 1
Forum section: electronics / beginners

author: simpson
author_rank: Contributor
timestamp: November 15, 2013, 07:27:54 pm
content: I just bought some of these 6-inch tall caps at a yard sale.When I got them home I tested them with a Fluke and an Agilent DMM and they all tested at approximately 5600 uF on both meters.This seems pretty far off the mark from 4400 uF but they all read within about 50uF of each other.I had the understanding that a bad cap would usually read less, not more than its printed spec if it was blown and I doubt a bunch of blown caps would all read nearly the same. So, what have I got here?I don't have an LCR or other more sophisticated meter to test them -- just DMMs with a capacitance feature.What is the opinion on this from you more experienced folks? Do my caps seem OK to you or is something probably wrong with them?

author: c4757p
author_rank: Super Contributor
timestamp: November 15, 2013, 07:44:48 pm
content: Measuring capacitance is useless to check for a bad cap. They either go leaky or high ESR. Those are just a bit on the high side. You'll notice they do not have a tolerance listed on them.

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 15, 2013, 07:45:28 pm
content: I'd say that at least your measurements didn't prove that they are not OK. I wonder what you'd measure when using 200-250volt, but that would be hard to do.

author: rr100
author_rank: Frequent Contributor
timestamp: November 15, 2013, 07:59:05 pm
content: In fact is rather easy, just charge them from mains with a diode and resistor (assuming you know how to protect yourself from live wires, exploding caps, etc) then discharge them through a known resistor. Watch the voltage on a high impedance (i.e. normal nowadays) multimeter and have a watch at hand.

author: Rufus
author_rank: Super Contributor
timestamp: November 15, 2013, 08:03:20 pm
content: Quote from: simpson on November 15, 2013, 07:27:54 pmThe data sheet tolerance of that particular capacitor is -10% +50%.

author: KJDS
author_rank: Super Contributor
timestamp: November 15, 2013, 08:36:04 pm
content: Quote from: Rufus on November 15, 2013, 08:03:20 pmMany caps of that size have a tolerance of -20% +80%. They're not precision items.

author: simpson
author_rank: Contributor
timestamp: November 16, 2013, 10:40:01 am
content: Thank you!
BIG HAUL - Page 1
Forum section: electronics / beginners

author: codingwithethanol
author_rank: Regular Contributor
timestamp: June 27, 2019, 05:26:30 am
content: I work at a radio station at my college, and I just dropped by today and found a HUGE pile of old audio equipment, odds and ends and whatnot, so I thought id share some photos. Also a question regarding the thing in the first picture, what the fuck is it? Looks like a giant capacitor with multiple leads, not sure how to even go about finding info on it. It was housed in a metal box thing with a very nondescript schematic inside, connected to two other capacitors. If anybody here has knowledge of audio equip, i'd love to know more.IMAGE GALLERY:https://imgur.com/gallery/6KNGAyj

author: bob91343
author_rank: Super Contributor
timestamp: June 27, 2019, 05:55:22 am
content: That isn't a capacitor. It's a transformer. There should be a name and part number on it somewhere.Most of the rest well it's anyone's guess. Miscellaneous circuits. The thing with all the knobs might be an audio mixer but I can't tell without seeing more of it.But the last picture is of a cordless soldering iron, very nice. I have always wanted one but could never justify buying.

author: codingwithethanol
author_rank: Regular Contributor
timestamp: June 27, 2019, 06:27:05 am
content: Yeah the bulk of what I found was old pots and specially designed selector switches. The construction of the majority of the parts is very robust and serviceable, as well as aesthetically pleasing. The Iso-Tip is one of the gems of the haul, I actually have to go back tomorrow and see if I can find the tips. Also I found a ton of old-school resistors, far better than those chinese Ebay ones that bend into pretzels if you try to breadboard them! Most of the IC's are Op-Amps and voltage regulators, specifically designed for audio applications.
Big power inductor (300 uH @ 200A) - Page 1
Forum section: electronics / beginners

author: hazuki
author_rank: Contributor
timestamp: September 02, 2020, 09:20:21 pm
content: Anyone know an easy way to find or design a large power inductor? I need around 300uH and the inductor shouldn't saturate until above 200A. Sounds like something custom for sure but I've never wound anything this size.Thanks

author: kaffine
author_rank: Newbie
timestamp: September 03, 2020, 02:43:02 am
content: Will this work?https://www.digikey.com/products/en/inductors-coils-chokes/fixed-inductors/71?k=&pkeyword=&sv=0&pv2088=u200A&sf=0&FV=-8%7C71%2Cmu300%C2%B5H%7C2087&quantity=&ColumnSort=0&page=1&pageSize=25

author: Wolfram
author_rank: Frequent Contributor
timestamp: September 03, 2020, 08:53:09 am
content: If you can find a scrap second generation Prius inverter, you might be able to use the boost inductor from that. 370 uH at no bias, and around 150 uH at 200 A. I don't think it can handle more than 100 A continously though, so it might not be good if you need to handle 200 A for more than a few tens of seconds. If this is for a switching converter with significant ripple fraction and you need 200 A continous current handling capability, you might just have to wind something yourself on a big set of Sendust E-cores.

author: Stray Electron
author_rank: Super Contributor
timestamp: September 03, 2020, 02:41:26 pm
content: Any of the big old transformer type DC welders will have an inductor like this in them. A lot of people are getting rid of their transformer type welders and replacing them with the smaller, more efficient inverter type welders so the big ones aren't hard to find and can occasionally be found in scrap yards. A large forklift battery charger may also contain an inductor like you want.There are service manuals available for the batter grades of welders (like Miller) and they list the size of the inductor used in them,

author: hazuki
author_rank: Contributor
timestamp: September 03, 2020, 03:44:24 pm
content: I am planning to run at around 55kHz. I really want 3 of these inductors to simulate a 3 phase motor stator. However I am only planning on very very short bursts of current, around 20ms. At a time. Basically just enough time to reach peak current and then I'll be shutting it down. So maybe a few of those laminated core (CH-200) would work for me?Also I took a look around and I found a company called mag-inc that sells large cores and provides calculators for how to wind them based on your current and inductance needs.https://www.mag-inc.com/Design/Design-Tools.Pretty cool.
Big Thank You to Dave. - Page 1
Forum section: electronics / beginners

author: Jwillis
author_rank: Super Contributor
timestamp: April 08, 2021, 04:18:02 am
content: Thank you so much for keeping us informed about the status of the forum and servers in the past few days. Awesome!

author: nuclearcat
author_rank: Unknown
timestamp: April 08, 2021, 05:47:09 am
content: And thanks for gnif for all his efforts!

author: nemail2
author_rank: Regular Contributor
timestamp: April 08, 2021, 07:30:13 am
content: yes huge shoutout to gnif!Quote

author: brucehoult
author_rank: Super Contributor
timestamp: April 08, 2021, 08:35:48 pm
content: Great to see it back!Is it my imagination, or is it even slower than before?

author: The Doktor
author_rank: Regular Contributor
timestamp: April 08, 2021, 09:01:36 pm
content: Quote from: brucehoult on April 08, 2021, 08:35:48 pmIt's not your imagination.

author: Capernicus
author_rank: Frequent Contributor
timestamp: April 08, 2021, 09:33:30 pm
content: AWESOME DAVE, I DIDNT KNOW ANYTHING ABOUT ELECTRONICS UNTIL I WATCHED ALL YOUR VIDEOS NOW I FEEL LIKE IVE FINISHED MY APPRENTICESHIP!!! thankyou.
Big Variable Power Transformer - Page 1
Forum section: electronics / beginners

author: jsi
author_rank: Regular Contributor
timestamp: November 12, 2017, 06:11:07 pm
content: I scored this variable power transformer at an estate sale. While I think it's cool, my hobby electronics is pretty much limited to low voltage DC stuff. There are a couple of similar items on ebay, but is that the best place to sell something like this?

author: SeanB
author_rank: Super Contributor
timestamp: November 12, 2017, 06:58:13 pm
content: Going to be heavy to ship, so likely only either local sale or buyer collection only.

author: IanB
author_rank: Super Contributor
timestamp: November 12, 2017, 07:05:39 pm
content: That looks interesting. Where are you located?

author: edpalmer42
author_rank: Super Contributor
timestamp: November 12, 2017, 10:56:36 pm
content: I have a smaller 220V variac. One interesting thing you can use it for is as an occasional 220V supply. Put the wiper in the middle and feed 120V between the wiper and one end. Pull the 220V from the ends. Your unit could put out 220V@7A from a 110V@15A circuit. Even more from a larger 110V circuit.Be sure you know what you're doing!!Ededit:Doh! Don't use the 'at' sign. The forum software thinks it's an email address!The first 'email address' is 220v at 7a. The second one is 110v at 15a.

author: schmitt trigger
author_rank: Super Contributor
timestamp: November 13, 2017, 01:53:12 am
content: I would lust for one of those.But it will weigh close to 200 pounds.As other poster mentioned, it will be a local pick up.

author: timb
author_rank: Super Contributor
timestamp: November 13, 2017, 04:09:39 am
content: Quote from: schmitt trigger on November 13, 2017, 01:53:12 amJust a tip for people in the US: If you need heavy items shipped on the cheap, but don’t want to shell out the hundreds it costs for freight, look into Greyhound (yes, the bus company). They will transport 250lbs cross country for essentially less than the price of a ticket. As long as the freight will fit in the cargo hold at the bottom of the bus, they’ll take it. (I once had a friend ship an antique coffee table this way!)

author: tecman
author_rank: Frequent Contributor
timestamp: November 13, 2017, 02:36:18 pm
content: You can run it on 120 rather than 240, like any transformer. Max current would be the same.paul

author: jsi
author_rank: Regular Contributor
timestamp: November 27, 2017, 08:35:44 pm
content: Thanks everyone - This bad boy can be yours! Here's the link to the ebay listinghttp://r.ebay.com/IOUzHV
Biginner, Hello, Bose 1801  - Page 1
Forum section: electronics / beginners

author: rezvordwg
author_rank: Newbie
timestamp: July 22, 2016, 03:33:26 pm
content: Hello everyone. I looked around on the site for help on previous posts. I've looked on eBay, Craig list and I'm really out of my league here. I'm searching for replacement front knobs for my Bose 1801. I have looked off and on randomly for a few years with no luck. I'm really impressed with the knowledge here, again I'm out of my league. I was a Certified welder in a large Industrial complex for 36 years, now retired. Mostly x-ray welds, but I feel intimidated ... If anyone knows where a fella can can find such an itwm I could sure use some direction... thanks Rez

author: Signal32
author_rank: Frequent Contributor
timestamp: July 22, 2016, 03:37:35 pm
content: Do you need the front knobs to look identical to the original, genuine one, or do you just need something functional?You might try contacting this seller to see if he has any he can ship you:http://www.ebay.com/itm/-/282080028386

author: rezvordwg
author_rank: Newbie
timestamp: July 22, 2016, 03:53:07 pm
content: I saw this add, one of many actually. I was on there again, looking this morning. Thank you, I will see. They dont need to be perfect. I have knobs that are not original on it now. I have some vintage high power equipment. However I am going to have to put some on Craigslist. The 1801 just looks cheezie with brown knobs on it...lol Thank you...

author: rezvordwg
author_rank: Newbie
timestamp: July 22, 2016, 06:32:19 pm
content: Nice man, Bill took my number, said he will see what he could do. However they are very special... So, still looking I guess...

author: Signal32
author_rank: Frequent Contributor
timestamp: July 22, 2016, 06:35:42 pm
content: There are also lots of knobs on eBay that might look similar to what you're looking for:http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=chrome+knobs&_sop=12Though you'll have to check the dimensions.Something like this:http://www.ebay.com/itm/-/151269799279
Binary counter troubles  - Page 1
Forum section: electronics / beginners

author: MechEng87
author_rank: Contributor
timestamp: October 01, 2016, 01:23:08 am
content: Hello everyone, I am new here and love the forum and the eev blog YouTube channels. I am working on a project for a counter that has me troubled. I am using g a 74ls163 binary counter and I am trying to get it to stop could time g at 9 and reset. I have done some looking online e and tried everything I can think of to get it to reset after 9 instead of counting all the way up to 15 then going g back to 0. I hope this isn't too basic a query but if anyone can help I'd appreciate it. I am working on building a light gate timer for velocity measurements.

author: ataradov
author_rank: Super Contributor
timestamp: October 01, 2016, 01:47:27 am
content: 9 is 0b1001 (8421), so your stop signal is: (1 & 8 ) & ~(2 | 4). You can obviously rewrite this into whatever logic gates you have at hand. In this case you need 2 AND gates and one NOR gate.

author: MechEng87
author_rank: Contributor
timestamp: October 01, 2016, 01:58:35 am
content: Ok, that's kind of were I was headed but so far nothing is working the way I expect. I tried putting a diode and gate with Qa and Qd as the inputs that would reset the timer on the next clock cycle but no luck. Is a diode AND gate appropriate? I'm using all 5 volt logic levels.

author: ataradov
author_rank: Super Contributor
timestamp: October 01, 2016, 02:01:41 am
content: You can make AND gate out of diodes, but AND gate alone is not enough here. And it is obviously better to use real gates for a real project.

author: KerryW
author_rank: Regular Contributor
timestamp: October 01, 2016, 03:38:29 am
content: Actually, if you just NAND Q0 & Q3, you would get a Reset pulse at 9, 11, 13 and 15, but since it would reset to 0 at a count of 9 it wouldn't matter.

author: ataradov
author_rank: Super Contributor
timestamp: October 01, 2016, 03:53:53 am
content: Quote from: KerryW on October 01, 2016, 03:38:29 amGood point. In that case diode AND should work just fine.

author: danadak
author_rank: Super Contributor
timestamp: October 01, 2016, 09:48:50 am
content: Do you have a race condition or not meeting PW for the reset signal ?A scope can help here, and look at datasheet to create a timing diagram tosee if you are not meeting chip timing.Regards, Dana.

author: MechEng87
author_rank: Contributor
timestamp: October 01, 2016, 04:36:45 pm
content: Got it! Thanks for everyone's help, I used an AND gate on q0 and Qd then fed it through an inverter and it works perfectly. I will just use a NAND gate as KerryW suggested. Thanks again everyone. I will post pics of it when I get the rest of the circuit going
Binding posts; extra parts? - Page 1
Forum section: electronics / beginners

author: Jebnor
author_rank: Regular Contributor
timestamp: May 22, 2021, 11:44:30 pm
content: I get why one set of lock washers (post, insulation, case, insulation, lock washer, nut. If you attach via ring terminal I can see the extra nut and washers. But why 6 washers and 4 lock nuts? Generous/nice manufactures or am I missing something?

author: Stray Electron
author_rank: Super Contributor
timestamp: May 23, 2021, 03:46:31 am
content: That binding post set actually follows Best Engineering Practices. The parts should be installed in the following order: the posts through the panel, then the plastic base, then each threaded posts should have a flat washer, a lock washer and then a nut installed and tightened. Those parts are simply to secure the binding posts to the panel. (The flat washer is there to protect the plastic from being chewed up by the lock washer.). Then install another flat washer, then a ring terminal attached to your wire lead. Then another flat washer followed by a lock washer and nut. A flat washer is used on each side of the ring terminal to prevent damage to it. The first nut, etc is there to secure the biding posts to the panel and the last nut, etc is there to secure the wire connection. You could omit the flat washers but the lock washers would chew into the plastic and/or the ring terminal. The flat washers also allow you to tighten or loosen the nuts without it trying to twist the wire ring terminals and possibly breaking the terminal to wire connection.

author: Jebnor
author_rank: Regular Contributor
timestamp: May 23, 2021, 06:21:08 pm
content: Ah, that makes sense. Thanks
Bipolar ADC or Unipolar ADC with summing amplifier? - Page 1
Forum section: electronics / beginners

author: Felicitus
author_rank: Regular Contributor
timestamp: January 10, 2014, 07:43:33 am
content: Hi,not sure if this is a beginners question, and may be more of a philosophical question.I'm designing a board which measures voltage. To be protected against user error, I decided to make it accept any polarity, thus I need to measure negative voltages as well. Most ADCs I have looked at are unipolar, so I digged into shifting the input voltage by a summing amplifier. The question is:Should I really use a summing amplifier in order to shift negative voltages into the positive range, or should I use a bipolar ADC?I have googled quite lots, but most designs I came across don't care about negative voltages at all.

author: Rerouter
author_rank: Super Contributor
timestamp: January 10, 2014, 08:56:32 am
content: if the input impedance changes the sum voltage rises so if its a controlled input device your ok, if its any old voltage not so much
Bipolar high voltage +/-100V@2A for ultrasound tranducer - Page 1
Forum section: electronics / beginners

author: Paptrack
author_rank: Contributor
timestamp: April 03, 2025, 02:09:44 pm
content: Hello,I’m designing an ultrasound pulser-receiver using either the HV7360 or HV7361. Both components can handle ±100V and outputs can source and sink up to 2A current. However, I’m struggling to find a suitable power supply that can deliver ±100V at 2A. Please find attached an image of the proposal.I´m not a experienced hardware designer, so I am searching for commercial AC/DC or DC/DC ±100V converters, but none seem to meet the 2A requirement. I also reviewed the HV7321, HV7351, or STHV748 demo boards, but non of them provide an explanation how to generate the required bipolar high voltage.The ultrasound transducer need to be applied a rectangular +/-100V 1MHz burst (configurable from 1 to 16 pulses). This burst will be applied once every 30 minutes.F02CT is an DC-DC converter that supplies bipolar +/-100V@50mA. As the transducer is driven only once per 30min, do you think this 50mA output converter would be enough.Any help will be appreciated.

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: April 03, 2025, 02:33:34 pm
content: Hello Paptrack,Something likethat?Two units are required.Ask the manufacturer if the output is truly floating. No connection is allowed between 0V on the secondary side and PE (Earth) on the mains side.By the way, any particular reason to design a custom US power driver ? Is it for an US (linear) motor ?US power boards areavailable off-the-shelf.

author: Paptrack
author_rank: Contributor
timestamp: April 04, 2025, 10:33:28 am
content: Thanks for your answer.

author: xvr
author_rank: Frequent Contributor
timestamp: April 04, 2025, 10:38:13 am
content: QuoteYes, if you will add appropriate capacitors on output (as power reservoir). Also current limiting resistor could be required to capacitors charging (DS listed 'capacitor charging' as one of typical application, but I have no other information about this). It has short circuit protection, but no information about how it works. It could be suitable to capacitor charging without current limiting resistor, or could be not

author: Paptrack
author_rank: Contributor
timestamp: April 04, 2025, 11:49:01 am
content: Thanks xvr, for your valuable contribution.
Bipolar supply for this microamp current source circuit - Page 1
Forum section: electronics / beginners

author: RichardM
author_rank: Frequent Contributor
timestamp: October 07, 2022, 09:11:35 am
content: Hi AllI thought I would have a go at making the low current source circuit attached, link belowhttps://www.edn.com/precision-programmable-current-source-uses-two-ics/It appears the LT1991 needs a bipolar supply. I was hoping to make this project run off a 9VDC (or similar) battery as apposed to mains AC. I have made several power supplies etc on my electronics journey and can make small single sided PCBs.Any suggestions on a circuit to do this or are there any DC bipolar modules available for such a task ? Or just connect two batteries (postive to negative to get + and - ?)Thanks for helping a beginner.Richard

author: PartialDischarge
author_rank: Super Contributor
timestamp: October 07, 2022, 10:37:01 am
content: Since you are using a battery use a TLE2426 to get a middle supply point

author: EPAIII
author_rank: Super Contributor
timestamp: October 08, 2022, 07:27:52 am
content: The TLE2426 seems to be a part made for this application, but virtually any inexpensive op amp plus two equal value resistors can perform this function for about half the price or less. Connect both resistors to + input and one to battery + and the other to battery -. Connect the output to the - input.

author: RichardM
author_rank: Frequent Contributor
timestamp: October 08, 2022, 09:06:01 am
content: Thankyou for both suggestions.

author: Terry Bites
author_rank: Super Contributor
timestamp: October 11, 2022, 07:36:46 pm
content: If its battery powered and not referenced to any external ground then a monodirectional current souce will do?Its just a matter of reversing the output terminals
Bistable application, but with a "pulse signal" - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: April 25, 2020, 06:33:25 pm
content: Hi,I have the circuit in the thumbnailwhich is used basically to multiplex a pin on an attiny.The problem is that the attiny I have has all of the pins used in this application, but I have to do an additional thing when the pushbutton are pressed, ie: toggle a bistable 555 timer.Here I use the words "bistable 555 timer" because my application would exactly behave as a single button (toggled) bistable 555 (not separate set/reset but single "toggle" button).The problem is that I actually don't know how to do the same thing (toggling the 555 or having something similar).The only thing that came to mind was an analog spst switch toggled by the output of the circuit and which basically acts as a "pushbutton" for the 7555 timer. Of course I would have to adjust or check the resistors to see whether the out voltage would coply with VIH. Anyway, although I run from battery and thus am concerned about consumption, I see that many spst analog switches have less than 100uA supply current draw, so I thought I am ok. But I think I can learn something about this circuit (I get the feeling there might be a more elegant solution). What can I do better?Cheers

author: james_s
author_rank: Super Contributor
timestamp: April 25, 2020, 06:52:51 pm
content: I'm not entirely clear on what you're trying to do. Does it have to be a 555? It sounds like what you want is a toggle flip-flop, you can do this with a D flip-flop by connecting the inverted output to the input, then each pulse of the clock input will cause it to flip states.

author: Moriambar
author_rank: Unknown
timestamp: April 25, 2020, 08:08:45 pm
content: Quote from: james_s on April 25, 2020, 06:52:51 pmIt doesn't have to be a 555. thanks
Bit-banging HVPP - Page 1
Forum section: electronics / beginners

author: rexxar
author_rank: Frequent Contributor
timestamp: May 01, 2014, 10:02:21 pm
content: Hi all, I borked the microcontroller in my project a few weeks back by programming the fuse bits wrong. Since I have zero money right now, I'm rather interested in reviving it so I can continue development.I have an Arduino Leonardo that I've been using as an ISP programmer, so I searched to see if I could use it as a high voltage programmer, and I came across Scratch Monkey, which is supposed to emulate an STK500 in ISP, HVSP, or HVPP modes. Unfortunately, I can't get it to doanything, so I decided that since I just need to reprogram three fuse bytes, I'd just manually drive all the pins and essentially bit-bang the HVPP protocol.So far, I've not gotten it to work, and I'd like some help debugging.First off, is this even feasible? How precise does timing have to be for HVPP? Is 1uS between commands too slow?I'm also confused about actually writing the bytes. The datasheet says that writing 1 clears a bit, and 0 programs it. Does that mean that I have to send, say, 0xE2 as 1110 0010 or do I need to invert it? I'm fairly sure I'm supposed to put the most significant bit on D7, is that correct?I've noticed that on the PWM pins, when you hold it high or low (which one it is depends on the pin), it seems to actually put a PWM value there instead of hard on or off. I worked around that by writing a 255 or 0 PWM value, but has anyone else noticed this behavior, or is there something wrong?If this turns out to be possible, I might make the code nice and allow for variable byte inputs, but for now it's just a long, long string of digitalWrites with hardcoded values

author: nerdyHippy
author_rank: Contributor
timestamp: May 02, 2014, 03:02:49 pm
content: Awhile back somebody made a 100% manual system for programming AVR using toggle switches, which would imply that for regular programming there isn't a minimum frequency requirement. I'd imagine that HVPP is the same.

author: amyk
author_rank: Super Contributor
timestamp: May 03, 2014, 12:35:10 am
content: There's amaximumspeedbut no minimum. For HVPP the oscillator doesn't even need to be running, it behaves more like an EEPROM.Manual HVPP has been done before:http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=19386
bit memory pattern - Page 1
Forum section: electronics / beginners

author: Gibson486
author_rank: Frequent Contributor
timestamp: November 28, 2018, 08:51:56 pm
content: I am looking at the datasheet for the AD9106.In the spec sheet, it says it has a 4096 x 12 bit memory pattern. What does this really mean in terms of how many data points it can store? Actually, what does it actually mean?Thanks!

author: senso
author_rank: Frequent Contributor
timestamp: November 28, 2018, 09:04:12 pm
content: It means that it has memory for 4096 12bit data points that can be used to create an output pattern, call it waveform memory if it makes easier to understand.

author: Gibson486
author_rank: Frequent Contributor
timestamp: November 28, 2018, 10:11:26 pm
content: I see, it just means that it holds 4096 memory spaces that are 12 bits wide? Sounds easy enough.

author: Brumby
author_rank: Unknown
timestamp: November 29, 2018, 12:23:30 am
content: Quote from: Gibson486 on November 28, 2018, 10:11:26 pmThat's it.
Bizarre behavior grounding constant current regulator SW pin - Page 1
Forum section: electronics / beginners

author: amaschas
author_rank: Regular Contributor
timestamp: February 04, 2022, 04:24:54 am
content: Hey all, I've run into a really weird behavior with a constant current LED driver circuit I'm testing on a bread. Basically what is happening is that the circuit is only outputting a fraction of the power that it should, but I discovered accidentally that if I touch the grounding clip of my oscilloscope probe (even with the oscilloscope off!!) to the SW net of the circuit, it suddenly starts working properly. I see the correct current output, and I also see the expected pulses from the SW pin at the correct duty cycle.The solution I am designing for requires a 28V input and drives 8x LEDs with a Vf of 3.15 for a total of 25.4V/0.36A output, but when I breadboard out the circuit, I get 18V @ 0.01A. I'm using this IChttps://www.ti.com/lit/ds/symlink/lm3402.pdf, and this is the schematic of my breadboarded circuit:I believe that the issue I'm having with the circuit is noise related, because when I probe the SW net (without the grounding clip connected) I see this on my oscilloscope.However, when I attach the ground clip I see the waveform I expect with the appropriate duty cycle.From what I understand, all that is occurring is that the SW pin is being connected to earth ground through the oscilloscope grounding clip. I actually sacrificed an IC to see what would happen if I simply grounded the pin, and I got the expected magic smoke. What exactly is happening when I connect the grounding clip?I've added photos of the breadboarded circuit with and without the IC mounted to see if there's a mistake I'm not seeing.

author: jmelson
author_rank: Super Contributor
timestamp: February 04, 2022, 05:30:46 pm
content: You really can't build these circuits on solderless breadboards. They run at very high frequencies. Your caps CIN1 and CF1 need to be very close to the IC pins.Jon

author: amaschas
author_rank: Regular Contributor
timestamp: February 04, 2022, 07:29:45 pm
content: Quote from: jmelson on February 04, 2022, 05:30:46 pmSo I'm not really trying to build this thing for any long-term purpose, I'm just attempting to work out some confusion I had from the design math to make sure that my input/output power will actually work with this IC. I know that using a breadboard to lay out a SMPS is going to result in a lot of noise, though I have successfully tested out other switching ICs on breadboards before. There is noise, and you would never use them for anything permanent, but it works to figure out if you've chosen the right passives and stuff like that.What is really puzzling to me here is that connecting earth ground to the SW node of the circuit suddenly makes everything work correctly. I've actually just connected the earth ground of my power supply to the SW node and it starts outputting 360mA as designed.
BJT base-emitter and base-collector junction capacitance - Page 1
Forum section: electronics / beginners

author: bonzer
author_rank: Regular Contributor
timestamp: February 25, 2019, 05:30:32 pm
content: Hello everyone. Please help me to understand how to find the base-collector junction capacitance in my case. I'm working on an exercise that has an amplifier circuit with two BJTs, as you said previously here in another thread it's an A class and what I'm trying to understand is what would be in this case of a 2N2222 base-emitter and base-collector junction capacitance. I have the values of these zero bias capacitances and the formulas (I attached here two slides). I use LTSspice for the simulation.What I want to know is how to find their values in the case of this circuit at like 400kHz? (I need them to apply a method for the superior cutoff frequency estimation)Allright - CJE is usally equal to 2*CJE0 so there's no problem with it (as shown in the slide).---MODIFIED-------And how about Cu? (base collector junction capacitance). I need to measure VCB. In small signal mode I have a control on frequency but it's all amplified so there're huge voltages as it's the differential mode component that we see. I measured it in transient time mode in LTSpice. I see at the second transistor (at right) 7.2V. But then we have negative denominator in the formula and it gives problems because there's a power (m) and even if ti wasn't we can't have a negative capacitance so please help me to understand what's the right way? What would you do?

author: bonzer
author_rank: Regular Contributor
timestamp: February 25, 2019, 08:18:34 pm
content: It looks like these formulas up are wrong, for example for the base collector junction it should be like here in the attachment with a sum at the denominator and not substraction. Then it makes more sense.In fact my project works well when using the values calculated with this formula attached.
BJT beta vs Hfe - Page 1
Forum section: electronics / beginners

author: king.oslo
author_rank: Frequent Contributor
timestamp: June 19, 2013, 10:17:53 pm
content: Hello there,Since the day when I began playing with BJTs, I understood that BJT beta = Ic/Ib, which is distinct from h_fe. Hfe is the value from the data sheet which is typical maximum current gain from that transistor in the common emitter configuration.Beta is amongst other things, dependent on the configuration of the transistor.When I know Q1 has a beta of 200, and I know the collector current is 6mA, base current must be 30u. Will somebody kindly confirm that this is correct? Due to recent event, I want to be sure that I have understood correctly.Hope it isn't too much trouble.Thank you for your time.Kind regards,Marius

author: jebcom
author_rank: Regular Contributor
timestamp: June 20, 2013, 12:56:45 am
content: Beta is also usually specified in the common emitter configuration, so Hfe is usually the same as DC beta.So yes, I believe you are correct, if the transistor is forward biased, 200 is the actual beta, and you are talking about DC.

author: jebcom
author_rank: Regular Contributor
timestamp: June 20, 2013, 01:05:34 am
content: And by the way, if you want to get it first hand from the Bible, you can read or download it here:http://ebookbrowse.com/ge-transistor-manual-1964-pdf-d258054104

author: Paul Price
author_rank: Super Contributor
timestamp: June 20, 2013, 01:07:06 am
content: Yes very true, but realize that Beta is a statistical variable and the actual Beta will be in a range around the specified value in a data sheet for a large group of the same transistor, so a Beta of 200 might be as much as 500 or more as little as 50, depending on the range of values specified in a data sheet.The Beta value is usually a "typical" value that varies with temperature and each device and especially with collector current.
BJT Biasing circuits - Page 1
Forum section: electronics / beginners

author: CoffinDodger
author_rank: Regular Contributor
timestamp: September 08, 2016, 01:22:36 pm
content: Anybody happen to have a good resource that explains the effect of the different forms of BJT biasing? Been going through my text book and some of my other home resource books and all I can find is: here's the what this bias circuit looks like! Now here's the equations, go play.Knowing a bit as to how the circuit effects the signal will help connect the dots to their equations. I've asked the teachers but it's a fast paced course so the response is usually "it's not all that important to your job, just get the equations on your reference sheet and recognize the circuit for the test."So far they "taught" yesterdayBase-biasEmitter-Biasvoltage-divider biasEmitter-feedback biasCollector-feedback bias

author: Lee Leduc
author_rank: Regular Contributor
timestamp: September 08, 2016, 02:07:52 pm
content: My go to book for transistor circuit design is "Electronic Devices and Circuit Theory" by Robert L. Boylestad and Louis Nashelsky, ISBN-10: 0132622262.https://www.amazon.com/Electronic-Devices-Circuit-Theory-11th/dp/0132622262/ref=sr_1_1?s=books&ie=UTF8&qid=1473342650&sr=1-1&keywords=boylestad+electronic+devices+and+circuit+theoryYou can save some money by buying it used. I buy used technical books fromhttp://www.alibris.com/andhttp://www.abebooks.com/.I've been told there may be an e-book or PDF version available for purchase.

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 08, 2016, 02:47:37 pm
content: Quote from: CoffinDodger on September 08, 2016, 01:22:36 pmglad you have your class sorted out, and glad you ask in the forum to show you care. so my advice is... a function generator, breadboard and oscilloscope. thats the only thing i know connecting the dots between books/equations/theories and the reality...ymmv.

author: CoffinDodger
author_rank: Regular Contributor
timestamp: September 08, 2016, 05:30:25 pm
content: Quote from: Lee Leduc on September 08, 2016, 02:07:52 pmThanks Lee! I'm checking that out now. I don't mind adding another resource book to the collection.Quote from: Mechatrommer on September 08, 2016, 02:47:37 pmThanks Mecha, luckily I have all those things. Time has just been against me. Luckily we're building some circuits today in the Lab so hopefully that'll help a bit. If not it's back to my own bench.
BJT capacitance data sheet - Page 1
Forum section: electronics / beginners

author: NoFilter
author_rank: Contributor
timestamp: March 04, 2021, 08:51:43 pm
content: Hi all,I am looking at some data sheets for BJT's and I noticed that some of the capacitance values are labeled as Cc, Ce, Ccb, Cce, Cibo, Cobo etc...For Ccb, Cce, it's obvious that it's the capacitance from the collector to the base (Ccb) or the collector to the emitter (Cce), but how do I determine what the other labels mean?For example, the attached image has a capacitance labeled Cc. Since the voltage being applied is VCB, is it safe to assume this is the Ccb capacitance?Lastly...is there a data sheet definition dictionary or something? It seems like data sheets all have similar data, but call it by different names...Thanks!

author: TimFox
author_rank: Super Contributor
timestamp: March 04, 2021, 09:16:42 pm
content: Traditionally, starting with vacuum-tube data sheets, a single suffix (e.g.,Cc) denoted the capacitance from that terminal to all the others. With transistors, the “o” in the three-suffix case (e.g.,Cceo) denotes that the other terminal (base in this example) is an open-circuit.

author: NoFilter
author_rank: Contributor
timestamp: March 04, 2021, 09:36:17 pm
content: Quote from: TimFox on March 04, 2021, 09:16:42 pmHi Tim,Thanks for the response!So when the capacitance is labeled asCc, like in the image in the original post, that is the capacitance between both the collector/base and collector/emitter (as shown in the attached image)?Thanks

author: TimFox
author_rank: Super Contributor
timestamp: March 04, 2021, 09:48:57 pm
content: I assume it means to short the base to the emitter, then measure the capacitance from the collector to that node.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 04, 2021, 11:01:41 pm
content: seehttps://electronics.stackexchange.com/questions/151982/how-are-cobo-and-cibo-defined
BJT & MOSFET transistor function - Page 1
Forum section: electronics / beginners

author: JerryLee
author_rank: Newbie
timestamp: November 28, 2015, 09:57:16 am
content: Hi Guys,I was searching for constant current supply circuit reference design that uses BJT or MOSFET and stumbled upon this design below.It is used to drive two LED to toggle at different time, meaning one would turn on and the other off and vice versa.RON & IRON: connected to logic OR gatesVCR & IVCR: connected to a digital-to-analog converter's outputWhat I'm trying to find out is how it actually works or operate, could someone help enlighten me?1) Let say RON is feed with logic 1 or 0- What will happen to the Gate, Drain and Source of MOSFET in term of voltage flow?2) Let's say IVCR is feed with analog input- What is the role of the IVCR in this design? To control the brightness of LED?- If yes how this works in term of current flow?Thanks

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 28, 2015, 11:07:51 am
content: Not sure why PMOS would be involved, the current sinks can be disabled by simply setting them to zero.Current is defined by the voltage on VCR / VCIR, and R27/R26. There's a strong tempco due to the transistor Vbe (~0.7V at room temperature, but up to 0.9V or more at low temperature, and 0.5V or less at maximum temperature).To put it fully,Ic = (VCR - Vbe) / R27In the < 0.7V range, Ic falls to ~zero with an exponential cutoff, and has an offset voltage (so it's ~zero by 0.2 or 0.3V, or at least as zero as the transistor will go, which is in the nA range).With R30/R23 present also, there is additional voltage drop, due to base current. I would suggest removing these resistors altogether (replace with 0 ohms, or a shorting jumper). As long as the DAC outputs can supply enough current, it will be fine. Base current is about 1/100th of Ic (the exact ratio is hFE, which varies as well, but is usually high enough).Note that the collector won't pull all the way down to the emitter, so all of this is only true as long as:V(LED1) > Ic * R27 + Vce(sat)(and so on for the other side), where Vce(sat) is usually small (~0.2V, unless the transistor is being ran at rather high currents).Tim
BJT propagation? - Page 1
Forum section: electronics / beginners

author: etstudent
author_rank: Regular Contributor
timestamp: September 08, 2012, 01:03:59 pm
content: I cannot find this anywhere in my books, I looked and looked, so any help will be appreciated.In a noninverting buffer made with a bipolar junction transistor , propagation delay is longest when operation?1 changes from saturation to cutoff2 changes from cutoff to saturation3 remains at zero4 remain in saturationMy guess is is 3 but that is just a hunch. Any help would be great, hints, whatever, thanks.

author: etstudent
author_rank: Regular Contributor
timestamp: September 08, 2012, 02:18:08 pm
content: Thanks, I'm sure its in here, and I'm just overlooking it. Thanks again for the help.

author: etstudent
author_rank: Regular Contributor
timestamp: September 08, 2012, 03:18:39 pm
content: Found it. I just overlooked it several times, unlined it and still missed it. That is why you gotta go through these books several times. Thanks for the help.
Bjt Spice - Page 1
Forum section: electronics / beginners

author: Shturval
author_rank: Newbie
timestamp: November 06, 2020, 07:20:05 pm
content: Hello, I am trying to understand how a bipolar transistor works. In this document (http://www.idea2ic.com/PlayWithSpice/pdf/G%20U%20M%20M%20E%20L%20-%20P%20O%20O%20N.pdf) on page 6, there are 3 parameters q1s, q2s and NqB. I cannot understand how NqB turns out. Can anyone explain how it is output? Thanks in advance.
BJT transistor current calculation - Page 1
Forum section: electronics / beginners

author: advark
author_rank: Contributor
timestamp: September 10, 2020, 09:30:06 pm
content: Hi everyone,I'm having some problem solve this circuit and I'm wondering what am I missing. Assuming Vbe is 0.7V and Hfe is 100. I want to calculate Ib and Ic.First off, I get VR3VR3 = Vcc *( R3 / ( R3 +R2 ))= 12 *( 1K / ( 1K +10K ))= 1.09VVR2 = Vcc - VR3= 12 - 1.091= 10.91 VSince Vbe is 0.7V and VR3 is 1.091V then VR4 must/should be 0.391V, because VR4 +Vbe should equals VR3.So Ib (which is the same as IR4) must be 0.391 mA (VR4/R4).The same goes for IR3 = VR3/R3 = 1.01 mAThen again, IR2 = VR2/R2 = 1.091 mAAccording to Mr. Kirchkoff, IR2 = IR3+ IR4 but 1.091 = 1.01 +0.391 is false...What am I missing here??? My guest is that because R3 is in parallel with R4 my initial formula is wrong. But how can I account for the Vbe drop in that formula (or is there another formula)?Thanks for any hints.

author: ledtester
author_rank: Super Contributor
timestamp: September 10, 2020, 10:02:18 pm
content: QuoteThat's just an approximation. It doesn't account for the current through the base resistor.Here's a simulation of the transistor biasing with the assumption that Vbe = 0.75V -- you can redo the calculation for a more conventional value of 0.6 or 0.7:Just create variables for the voltage and current for each node, write out the relationships between them and then solve the system of equations.

author: John B
author_rank: Frequent Contributor
timestamp: September 10, 2020, 10:21:46 pm
content: Yeah some textbooks just assert that the voltage at the base node will be the same as a voltage divider rule, but that is only approximately close when the current through the resistors is orders of magnitude greater than the base current, therefore introducing only a small error.
BJT transistor model 2 - Page 1
Forum section: electronics / beginners

author: edba
author_rank: Contributor
timestamp: February 04, 2021, 08:06:52 pm
content: How do you switch off the parameters of the BJT gummel and poon so that is simplifies to the ebrs moll. Is there a good write up anywhere explaining all the parameters apart from the LTspice help files

author: Terry Bites
author_rank: Super Contributor
timestamp: February 05, 2021, 09:27:56 am
content: Why