hybridfree/eevblog-posts huggingface dataset:
B3603 alternative for +-12V - Page 1
Forum section: electronics / beginners

author: charonme
author_rank: Newbie
timestamp: April 24, 2018, 12:08:38 pm
content: could you please recommend an alternative for the B3603 which could I use to generate +12V, GND, -12V and have current limiters and ampmeters on both rails? (<300mA is sufficient, noise doesn't matter much)I tried connecting two B3603s to a mean well +-15V PSU but they apparently can't work like that

author: madires
author_rank: Super Contributor
timestamp: April 24, 2018, 12:47:06 pm
content: How did you wire the PSU and the two B3603s? A diagram could be helpful.

author: charonme
author_rank: Newbie
timestamp: April 24, 2018, 01:16:46 pm
content: There is 2.8v potential between the first out- and the second out+.When I connected them, I measured <1mA through the connection, but the second B3603 outputted 14.8V regardless of what voltage I set the B3603 to output.The same happened when I tried connecting out+ to the mean well com

author: madires
author_rank: Super Contributor
timestamp: April 24, 2018, 02:05:23 pm
content: I've found a circuit diagram for the B3603 onhttps://github.com/baruch/b3603. If you have a look at the voltage & current controls you'll see what causes the issue (feedback tied with local Vcc). I don't know any similar modules, but I'd recommend to check their circuit before buying. Otherwise you might run into the same problem again. Or you could go for a classic lab PSU design with opamps and pass transistors.

author: charonme
author_rank: Newbie
timestamp: April 25, 2018, 06:39:20 am
content: that's why I'm looking for a similar module that would give me +12v, gnd and -12v (the voltage doesn't even have to be adjustable)

author: charonme
author_rank: Newbie
timestamp: April 25, 2018, 12:57:41 pm
content: I just realized I could try this

author: charonme
author_rank: Newbie
timestamp: April 26, 2018, 04:22:26 pm
content: nah, didn't workI'll probably have to look for a cheap benchtop psu with +,- and gnd outputs

author: madires
author_rank: Super Contributor
timestamp: April 26, 2018, 05:36:58 pm
content: Do you need the PSU to power a specific project or for typical lab use?

author: charonme
author_rank: Newbie
timestamp: April 27, 2018, 08:32:44 am
content: specifically for testing equipment (based mostly on opamps) that is powered by +12V and -12V power

author: madires
author_rank: Super Contributor
timestamp: April 27, 2018, 09:30:35 am
content: In this case I'd recommend a small linear regulated lab PSU. Cheap lab SMPSUs are quite noisy.

author: nanofrog
author_rank: Super Contributor
timestamp: April 27, 2018, 01:20:38 pm
content: Quote from: madires on April 27, 2018, 09:30:35 amSeconded.Check the used market, as you'll do a lot better there IME. Dual, triple, and quad channel supplies offer a better value than a bunch of individual ones.Do get one that has both CV (constant voltage) and CC (constant current) capability. You'll want max voltage of 30V or so, which will allow you to power up op-amps (i.e. part may specify +/-20V).
Back EMF in Solenoid - Page 1
Forum section: electronics / beginners

author: QwertyXP
author_rank: Newbie
timestamp: October 26, 2013, 07:21:48 am
content: Consider an ideal solenoid (no resistance, no leakage reactance etc.) connected across an AC supply. The back EMF induced in it will be exactly equal and in opposite direction to the source voltage (which means that when a certain terminal of the AC supply is positive, the side of solenoid connected with it would also be positive, and vice versa).My question is, how will current flow at all when the EMFs of AC source and solenoid are cancelling each other out? It's like having having a circuit with only two batteries and terminals of similar polarities shorted with each other. The equation below doesn't appear to be balanced:V(source)=Back EMF (which is equal to source) + CurrentxReactancewhen back EMF is equal to source, the CurrentxReactance part should be zero!?I've read quite a few explanations on the internet but have yet to fully understand what's happening here.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 26, 2013, 07:39:24 am
content: The Back EMF doesn't happen instantaneously.Current has to flow through the coil,setting up a magnetic field before a Back EMF can be present.This is a basic characteristic of an Inductor.

author: IanB
author_rank: Super Contributor
timestamp: October 26, 2013, 08:58:21 am
content: Quote from: QwertyXP on October 26, 2013, 07:21:48 amI don't think so.QuoteBut they are not cancelling each other out.QuoteBut there should be no back EMF in that equation.The correct equation for average AC values in an AC circuit is:voltage = current x reactanceIf you know two of these you can calculate the third.The exact equation for an ideal inductor using instantaneous voltage and current is this:v = L di/dtv is the instantaneous voltage, L is the inductance and di/dt is the instantaneous rate of change of current.Since this is a differential equation you have to solve it by integration. If you find the solution where v(t) is an AC sine wave, you will find the current i(t) is also a sine wave, but it lags the voltage by 90 degrees.

author: Simon
author_rank: Unknown
timestamp: October 29, 2013, 04:34:09 pm
content: I suspect this may be a spammer laying down innocent threads ready to dump links and crap in their sig
Back to Back MOSFET Design - Page 1
Forum section: electronics / beginners

author: w.ashcroft
author_rank: Newbie
timestamp: October 19, 2017, 01:47:16 pm
content: Hello,I have a WiFi enabled AC mains light dimmer/switch that uses a back to back MOSFET design. The device sits in series with the load (lightbulb) and therefore does not have its own return/neutral connection.I'd like to understand how its MOSFET / transistor arrangement works as I'm not fully confident I understand how the control circuitry might be managing the MOSFETs and transistors so that a) it always has power for itself (a tiny amount of current flows through the lightbulb at all times, but not enough to light it); and b) so that a controlled amount of current is allowed to flow through it when any level of light brightness is requested.Ultimately, what I'd like to do, is convert the device to be a user input device only (with minimal modifications to the circuit), connecting directly to the supply and neutral - by somehow disconnecting the path between the two MOSFETs to prevent shorts. This may seem like a pointless exercise/idea, but actually it would then give me a dimmer that I can use in software as a user input.Edit: I may have answered my own question.. Could I do this simply by disconnecting the base of each transistor so that there is never a direct path between the two sides (i.e. pin 3).Many thanks for any help and advice.

author: w.ashcroft
author_rank: Newbie
timestamp: October 19, 2017, 01:48:18 pm
content: Here is the actual PCB I reversed (the terminals are SUPPLY, NO CONNECTION, LOAD).
back to back transformers  (for isolation) - Page 1
Forum section: electronics / beginners

author: J4e8a16n
author_rank: Regular Contributor
timestamp: January 10, 2016, 08:26:31 pm
content: Hi,My 2 multimeters gives me 14 volts. ?ThanksJPD

author: IanB
author_rank: Super Contributor
timestamp: January 10, 2016, 08:56:05 pm
content: So?

author: Zero999
author_rank: Super Contributor
timestamp: January 10, 2016, 09:00:19 pm
content: Come on IanB, this is the beginner section FFS!Yes, this is common and is caused by capacitive coupling between the windings.

author: IanB
author_rank: Super Contributor
timestamp: January 10, 2016, 09:09:06 pm
content: OK, a little harsh perhaps. I just thought a little more effort could be put into formulating the question.

author: J4e8a16n
author_rank: Regular Contributor
timestamp: January 10, 2016, 09:37:18 pm
content: I tought maybe the tranformers where to close to one another...They are cheap too : 10$ each.I like that: "Yes, this is common and is caused by capacitive coupling between the windings."JPD

author: tggzzz
author_rank: Super Contributor
timestamp: January 10, 2016, 09:48:57 pm
content: In future, you may find some of thesetipshelp you avoid provoking an unwanted response.

author: timb
author_rank: Super Contributor
timestamp: January 10, 2016, 10:38:39 pm
content: When I read the thread title, I pictured the "Ass to Ass" scene from Requiem for a Dream, only with transformers. Reading the thread left me disappointed and unfulfilled.
Back to Basics: How to make a peak-to-peak voltage measurement on a scope - Page 1
Forum section: electronics / beginners

author: w2aew
author_rank: Super Contributor
timestamp: October 20, 2014, 02:30:53 am
content: I put this video together by request to show the most important, basic considerations to understand when making a simple peak-to-peak voltage measurement on a scope. Yes, there are a lot of additional subtle details that are not in this video, but I wanted to keep it short and cover the basic requirements and process, and address the most common mistakes and problems people run into.
Back to the OneWire DS2502 and its programming Voltage (12V) - Page 1
Forum section: electronics / beginners

author: jwhitmore
author_rank: Regular Contributor
timestamp: March 08, 2018, 02:44:16 pm
content: This is a project which I keep coming back to as I've never solved the problem of switching the programming voltage (12V) to the DS2502 and turning it off again, without potentially upsetting the uC. I'm sure there is a simple fix for this, possibly a high value pull down resistor? But it's in the beginner section for a reason.The difficulty is going to be communicating the necessary information, and a question that can be answered, but here goes.So I have three pins of a uC connected to a "programming" circuit. They're labeled in the schematic:PD0 - This pin is the uC's connection to the One Wire bus. It has to be disconnected from the One Wire Bus when 12V Programming pulse is applied to the line. (The DS2502 requires a 12V programming pulse to write data to the write once EEPROM.)Disconnect - This pin controls disconnecting the PD0 pin of the uC from the One Wire Bus when the programming voltage is applied. So when it is High it "turns on" Q2 pulling the gate of Q1 to ground so Q1 is "turned off", disconnecting the uC from the One Wire bus.Program - This pin controls connecting the 12V supply to the One Wire Bus. When it is high it "Turns on" Q3 shorting the gate of the P Channel Q4 to ground, "turning on" Q4.At present I've got the two control lines, "Disconnect" & "Program" connected to the uC but not the "PD0" pin, just checking its behavior during the transition from 3v3 to 12V on the One Wire Bus and back again.When the 12V programming pulse is connected to the One Wire Line it all behaves. PD0 is temporarily pulled to ground but that's not going to harm anything.The problem is that when I turn off the 12V programming pulse there is a spike on the line. I've separated the two control lines so that I can turn off the 12V connection to the line and after a short pause I can reconnect the uC pin 'PD0' back to the One Wire Bus. I'll try to attach two scope traces to this question with the following key:PD0 - Yellow traceDisconnect - BlueProgram - PinkAt present I have a very short delay between turning off the 12V programming voltage and re-connecting the uC to the One Wire line. It's 272nS according to the scope trace but I've tried longer delays and it makes no difference at all.So now given that spike I assume that, even though the 12V is disconnected, when the pink line, 'Program' goes low in the scope trace, there is stray capacitance on the One Wire so the 12V charge has no where to go. So is the answer to attach a high value pull down resistor, say 1M, to the DS2502 side of the One Wire bus? That'd mean a pull resistor to the 3v3 on the uC side of the bus and a 1M pull down on the DS2502 side, but is that a problem?I hope that makes a little bit of sense to the reader.I'm going to solve this puzzle eventually, with a lot of help :-(
Bad connection - Page 1
Forum section: electronics / beginners

author: Jacktron
author_rank: Contributor
timestamp: September 07, 2024, 12:24:37 am
content: Can someone please explain to me why this is a bad connection?

author: Andy Chee
author_rank: Super Contributor
timestamp: September 07, 2024, 12:40:09 am
content: Works for me:https://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWcMBMcUHYMGZIA4UA2ATmIxAUgoqoQFMBaMMAKABsQU89xCqAWOLypUIMSMwTYE-BGH7YwkfsULZykFgDdwGQuGIpd+rj1HJqIqNAQsA7sYNGwe4VHuOwfTtzeaH-Pw8piCBPF4iHmFugqLe-o4h0SGaQA

author: Jacktron
author_rank: Contributor
timestamp: September 07, 2024, 12:47:07 am
content: maybe it is because my phase offset is 180 degress

author: Andy Chee
author_rank: Super Contributor
timestamp: September 07, 2024, 01:01:24 am
content: Nope. I changed my phase offset in my circuit and it still works.I believe your bad connection is this:

author: boB
author_rank: Frequent Contributor
timestamp: September 07, 2024, 01:23:03 am
content: Lettuce know if Andy Chee's version works for you
Bad design for a remote keypad? - Page 1
Forum section: electronics / beginners

author: LoveLaika
author_rank: Frequent Contributor
timestamp: September 08, 2022, 06:48:30 pm
content: Something's been bothering me. I have a remote keypad (typical rubber membrane keypad). It opens a garage door. Enter in the code, press the big red arrow, and the door opens. Pretty straightforward, right?There have been times where after I press the arrow (after entering the right combination), it flashes in a way that indicates the code is bad. I start entering the code again, but after the first digit, the door opens up. This feels very weird, and it kind of feels like a security flaw. Is this a security flaw? It feels like it recognizes the code, but maybe I entered it too quickly. Kind of feels like there's no proper debouncer to register the inputs, but why would it open when I reenter the code?Sorry, I'm not really looking for a way to fix the thing. I was just curious about the phenomenon. Most likely, doing so would void the warranty. I'm just asking about it here because this feels like bad product design somehow, and I'm not sure what a potential hardware solution would be. Only solution i found was to enter the code slowly at a frequency of 0.5 Hz (heh heh).

author: rooppoorali
author_rank: Regular Contributor
timestamp: September 10, 2022, 10:50:50 am
content: It is a ready-made product that you bought, right? Did the supplied give any service warranty? If so, I think it's the best option to approach them for fixing it.
Bad fuzes - Page 1
Forum section: electronics / beginners

author: rdagger
author_rank: Contributor
timestamp: July 09, 2018, 05:56:56 pm
content: I bought an assortment of 5x20 fuses on eBay. I hooked up an 8A fuse to a 120VAC circuit and plugged in a 13A hair dryer. I ran it on high for about 2 minutes and the fuse didn’t blow. My meter read 12.9A.They look like AC fuses. The fuse is stamped F8AL 250V. I know AC and DC fuses have different ratings. Could they be DC instead?I guess I should have known better because the auction description described them as High Quality Fuze which seems applicable.

author: schmitt trigger
author_rank: Super Contributor
timestamp: July 09, 2018, 06:02:19 pm
content: Fuses have so-called I-squared-T curves, and depending on the ratings, some can withstand an overload for quite some time.Google:I2t

author: Fsck
author_rank: Super Contributor
timestamp: July 09, 2018, 06:03:17 pm
content: a fast blow 8A fuse will take way longer than 2 min to blow at 13A usually.A fuse is designed to interupt serious overcurrent, not just a tiny overcurrent.Look at the time-current chart for an 8A fuse in this datasheet as an example:https://www.mouser.ca/datasheet/2/643/ds-CP-5sf-5sfp-series-1313110.pdf

author: wraper
author_rank: Unknown
timestamp: July 09, 2018, 06:14:09 pm
content: Fuses normally can survive like 1.3 - 2 times of the rated current for like a minute and a lot longer once you lower the current a bit. That multiplier usually is on the lower side for low current ratings and on high side for higher current ratings. Although I would not buy fuses from ebay, using safety devices from dodgy source is not smart. DC/AC does not matter for current they'll act. It matters for how high voltage and current they can break safely.

author: rdagger
author_rank: Contributor
timestamp: July 09, 2018, 07:10:20 pm
content: Very helpful!Thanks for taking the time to explain.
Bad li battery pack, what am I missing - Page 1
Forum section: electronics / beginners

author: Seekonk
author_rank: Super Contributor
timestamp: January 28, 2017, 05:01:47 pm
content: My laptop came up with a notice "recommend replacement of battery pack". I've been expecting this for years, date code on the computer is 1110. They are cheap enough so I ordered another. I've been scavaging batteries from these packs for years so thought I might rebuild this one as a spare. I've built a micro based li tester and bad batteries have always been easy to spot. Popped the cover on the pack and each battery measured 4.27V, that seemed a little high for a pack that had been pulled out for days. Then I used a 3.9 ohm (about 1A) resistor as a load, 3.59-3.64V after 30 seconds. Unloaded the batteries still 4.26V after load test. Seem pretty good to me as I only run on line power. Am I missing something or does the laptop just have a timeout after so many years? If so, is there a reset?

author: Ian.M
author_rank: Super Contributor
timestamp: January 28, 2017, 05:15:24 pm
content: Do a timed constant current discharge test down to 3V/cell and compare with nominal capacity. Calculate the current to use from the laptop's specified running time and the cell capacity.To get a laptop to reset the S.O.C. statistics stored in the battery's ID chip and recalibrate capacity, one normally has to do a full uninterrupted charge/discharge cycle at least once. If you always run on mains power it wont have reached the max discharge threshold very often if at all so the estimated capacity will be very unreliable.

author: Audioguru
author_rank: Super Contributor
timestamp: January 28, 2017, 05:24:11 pm
content: An old lithium battery can hold its unloaded voltage for many years. Its age deteriorates it so its voltage drops when loaded but goes back up to normal voltage with no load because its internal series resistance has increased.I have Ni-MH cells that do the same. A good charged AAA cell can provide 7A to my current meter that shorts it but an old charged cell with exactly the same unloaded voltage cannot provide 1A.I agree that the capacity of a Lithium battery that is stored fully charged, has been discharged to a voltage lower than about 3.2V or has been discharged and charged more than about 500 times has reduced capacity.I won't talk about the lack of quality (too much rice powder in them) of Chinese batteries.
Badge Get - Page 1
Forum section: electronics / beginners

author: codingwithethanol
author_rank: Regular Contributor
timestamp: November 20, 2019, 01:19:54 am
content: A while back I made some threads here asking about LED brightness and SMD switch supports, this is just an update as to how the badge turned out, and a thank you to everyone who made a reply. Anyways as you can see by the pictures, I decided to go with all blue LEDs, I made an error when designing the circuit which is why 5 blink bright and 5 are barely visible. As it turns out the 555 timer has a substantial voltage drop from Vcc to output when high, which is why the timer is unable to bias LEDs when active. However when low, the output drops all the way to 0V, and the other LEDs see the entirety of the CR2032s 3V across them. I'll fix this unfortunate glitch with a MOSFET in the future. Also regarding the switch, i've included a closeup of my crap soldering skills for criticism. Also as you can see, I removed the support holes to preserve the design on the front and clipped the legs off the actual switch. This was actually my first PCB design ever, and I think it turned out pretty well. This was actually designed for a business pitch event, so I'll tell you if we win Friday night.P.S. The threads in question arehttps://www.eevblog.com/forum/beginners/match-led-brightness/andhttps://www.eevblog.com/forum/beginners/not-all-the-way-through-hole-in-pcb/
BAFFLED - Unipolar Output to BiPolar Amplifier??? - Page 1
Forum section: electronics / beginners

author: Majorassburn
author_rank: Regular Contributor
timestamp: February 25, 2024, 08:49:46 pm
content: I'm baffled and confused.A Mind BlockHELP ME PLEASE.Here's my dilemma:1) I have a subassembly with an on-PCB single 12VDC power supply. It generates a unipolar 1KHz, 2Vrms, ac-coupled output sine wave referenced to its circuit ground.2) I have to amplify that 2V sine wave to approximately 6Vrms.3) I have another subassembly with an on-PCB dual +12 /-12VDC power supply, ac-coupled input to an op-amp x3 inverting amplifier which could output a 6Vrms bipolar ac-coupled signal referenced to its own circuit ground.4) Both subassemblies must share the same common circuit ground.Problem:The unipolar 2V output from the first subassembly is processed and output by the second subassembly but only as an amplified UNIPOLAR signal rather than a BIPOLAR signal. (Unipolar swings from +12V to Ground. Bipolar needs to swing from approximately +9V to -9V, about 18Vp-p, above and below Ground.)What am I missing here? Thanks in advance for suggestions or solutions.

author: Kim Christensen
author_rank: Super Contributor
timestamp: February 25, 2024, 09:02:11 pm
content: Faulty/leaky coupling capacitor between the 1st amp pcb and the 2nd one?Post a full schematic of the entire set up.

author: Konkedout
author_rank: Frequent Contributor
timestamp: February 26, 2024, 12:27:28 am
content: As Kim said, we really need to see a schematic diagram.But it is not strictly necessary to AC couple the signal to take a unipolar signal into a bipolar powered op amp and get a bipolar output. This can also be done with proper biasing. And there is some chance that the op amp may be set up to do this, but you defeated the purpose by AC coupling the input signal. (??)

author: Majorassburn
author_rank: Regular Contributor
timestamp: February 26, 2024, 02:15:18 pm
content: Schematic on the way............
BAKU BK-601D heat gun failure - Page 1
Forum section: electronics / beginners

author: ruky23
author_rank: Newbie
timestamp: February 12, 2022, 03:36:06 pm
content: hello allme new to ur world, i come in peace, please forgive silly mistakes..My crappie chinese made BAKU BK-601D bought online has given up on its heat gun abilities all of a sudden.The fan works, the magnetic sensors on the handle work fine but just cold air(only fan) the element seemd not to be heating up anymore.So, i just did a rework job on an old amd r9 and dice too! so it was working fine sand then the other day i fired it up and only cold air, visibly no "hot fiery look" around the rim of the gun.Any idea what's wrong with this? i took apart the gun and inspected it for any discoloration, burning and so on but nothing.Any help appreciated before i have to invest in another rework station, many many thunks!!
Balanced audio output - how to measure CMRR - Page 1
Forum section: electronics / beginners

author: Saimoun
author_rank: Frequent Contributor
timestamp: February 24, 2021, 10:13:00 am
content: HiI've been reading this page:https://sound-au.com/articles/balanced-io.htmAnd I was wondering how does the author measure the CMRR on this circuit?Another question: if I have a similar circuit but on the first opamp U1.A I have a variable gain instead of a buffer, does that affect the balanced configuration? My circuit is attached.Thank you!Simon

author: mikerj
author_rank: Super Contributor
timestamp: February 24, 2021, 12:26:08 pm
content: If the output is perfectly balanced there will be no signal present at the node marked "CMRR". I suspect the author simply used a scope on this node and adjusted the phase network and gain resistors of the second stage to minimise the signal over the frequency of interest.Increasing the gain of the first stage should be possible provided you don't go to extremes.

author: Saimoun
author_rank: Frequent Contributor
timestamp: February 24, 2021, 01:58:31 pm
content: Alright I thought there was more to it but a simple AC analysis with a bode plot in Tina TI gives me the same results he gotThank you!
Balancing IC S19190E suitability - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: January 08, 2017, 06:13:48 am
content: I need a balancing solution in battery pack. Only balancing is required no other function is need.http://www.sii-ic.com/en/semicon/datasheets/automotive/automotive-lithium-ion-battery-protection-ic/s-19190/1. This IC has two functions, overcharge detection & cell balancing. I dont need overcharge function, so can I leave CO pin open & use its balcing function IC?2. Battery pack has 20 series cells (2.5V-4.2V each). So can I stack these 20 IC, for on series cell each.I think we can do it, since each IC runs on individual cells only. But there no application circuit for this in datasheet.3. What is the max balancing current I can set in each IC.ICB = VBU / (RCBON + RCB)Vbu = 4.15VRCBon = 5ohmsuppose Icb = 100mAthen Rcb = 36.5ohmWattage = 100mA * 100mA * 36.5 = 0.365WWattage dissipation in IC = 100mA * 100mA * 5 = 0.05WI think this can work:http://www.digikey.com/product-detail/en/vishay-dale/CRCW251236R5FKEG/541-36.5AFTR-ND/1173543But what's the max balancing current that can be set so that IC can have its proper operation. Entire balaning current passes through, 5ohm Rdson of the IC.Figure 7 in datasheet shows power dissipation power? How to calculate max balancing current, so that IC work when PCB is in IP68 box?What differnce in board 1 & 2 makes as below Figure 7, whether its 2 layer or 4 layer? Since track connections are both on same?

author: ebclr
author_rank: Super Contributor
timestamp: January 08, 2017, 08:36:21 am
content: http://www.ti.com/tool/bq76pl455evm?keyMatch=battery%20monitor&tisearch=Search-EN-EverythingAdd 4 of those that you mentioned
Balancing solar charged parallel 12V AGM batteries. Adding 12V & 24V outputs. - Page 1
Forum section: electronics / beginners

author: Jay72
author_rank: Newbie
timestamp: December 10, 2021, 11:31:26 am
content: Balancing solar charged parallel 12V AGM batteries. Adding 12V & 24V outputs.Was just thinking about a Campervan 'two AGM batteries in parallel solar setup' and wondering if it is possible to have 12V and 24V outputs, whilst charging with solar panels.The idea being to balance charge the batteries, using 24V for a fridge (less power loss over the length of cable) and two separate 12V outputs from the batteries.Thought I could work out a quick answer, so I quickly drew three circuit diagrams, but looking at them, not so good. I think there will be a short circuit or similar problem through the cabling and/or the devices.I've asked on fbook and it was replied that the circuits needed to be isolated and that there probably wasn't anything 'off the shelf'.I emailed a solar manufacturer, but they couldn't answer the question.Is this something that is electrically impracticable/impossible?Is there a simple workaround that I've missed?Mk1 - s/c on charging outputs?Mk2 - thought this might work.Mk3 - fail, needs a battery in the charging circuit, but could the inverters or chargers be connected to the charging output of the MPPT controllers?Thanks in advance for any advice or where to find an answer - not desperate, just curious.Jayau/renogy.comDCC50S 12V 50A DC to DC Battery Charger with MPPT - negative groundingRover Li 20 Amp MPPT Solar Charge Controller - positive grounding?youtube // Adam Welch // Renogy Rover PG MPPT Solar Charge Controller

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: December 10, 2021, 12:43:32 pm
content: The short answer really is that any system where you have two 12v batteries in series to make 24v, but you take some 12v power from just one of the batteries as well, is doomed to fail.For the 12v batteries to work properly in series they must have exactly the same amount of charge and discharge. You can use a battery balancer e.g. Victron make one (https://www.victronenergy.com/batteries/battery-balancer) but this really is only to account for slight physical differences between the two batteries.If you take power independently from the 12v batteries, they can never both be charged properly.There is no way to engineer this system that won't be massively more expensive that just buying some chunkier cable to supply your fridge with 12v.

author: Jay72
author_rank: Newbie
timestamp: December 20, 2021, 11:43:12 am
content: Thanks Denzil. I appreciate your reply, Jay.
Banana jacks - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: September 08, 2020, 02:03:51 am
content: Is there any higher quality option for banana plugs for making DIY cables to be used with test equipment?I can only find the very cheap red and black kinds that are of very poor quality and the very fancy gold plated ones for A/V use. However, the A/V ones, while they may be built nice, don't have protective shrouding, and i want to be able to send over 10A through the plugs and not worry about it.Any suggestions would be appreciated, i've been hacking apart budget test leads from ebay for too long.

author: wizard69
author_rank: Super Contributor
timestamp: September 08, 2020, 02:17:42 am
content: There are all sorts of options and frankly you just missed a long thread on this subject. I won't repeat my post there due to the time issue. However it is important to realize that you can order the parts to make your cables and jack solution pretty robust, just check with vendors like Newark, Digikey, Mouser and so forth. Probably the most important thing here is to make sure you have wire suitable for 10 amps.

author: Mp3
author_rank: Frequent Contributor
timestamp: September 08, 2020, 03:10:19 am
content: Quote from: wizard69 on September 08, 2020, 02:17:42 amI will look through your post history for that thread!

author: rstofer
author_rank: Super Contributor
timestamp: September 08, 2020, 01:16:05 pm
content: These banana plugs and jacks from Pomona are among the best around:https://www.pomonaelectronics.com/products/banana-plugs-jacks-and-hardware/banana-plugs-and-jacksMany are available at DigiKey and other top-line suppliers.

author: Vovk_Z
author_rank: Super Contributor
timestamp: September 08, 2020, 02:26:59 pm
content: BC104, CL1505 are not bad.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: September 08, 2020, 03:22:24 pm
content: Quote from: rstofer on September 08, 2020, 01:16:05 pmAnother vote for Pomona. Just got some 5-ways in to upgrade my solderless breadboard.
Banana jacks / binding posts on PCB - Page 1
Forum section: electronics / beginners

author: joeyjoejoe
author_rank: Frequent Contributor
timestamp: January 07, 2019, 12:14:01 am
content: I want to get some binding posts on a PCB but I have no clue what to do.At first I thought I'd go with a Cal Test 2232 (http://www.caltestelectronics.com/documents/Cal_Test_Cat_No_23.pdf) but I'm not sure if that will work.The cheap fabs have ~6mm maximum hole size. But, is this for plated through holes? Can I just drill/mill any 'ol size hole pattern I want, and put some copper around that hole on the surface that makes contact with the nut, which holds the binding post?This is for extremely low current, but it would be nice to know in general what is the practice.

author: Jwillis
author_rank: Super Contributor
timestamp: January 07, 2019, 12:43:15 am
content: If your mounting directly to the board the hole size only needs to be a wide as the threaded pin and just nut it directly to the copper.Or you can do something like this.https://learn.sparkfun.com/tutorials/benchtop-power-board-kit-hookup-guide/allor if you need it to be 90 degreeshttps://www.chk-electronics.com/PCB-Mounting-Terminals/or thesehttps://www.walmart.ca/en/ip/Replacing-Binding-Post-PCB-Mount-Banana-Socket-4mm-2-PCS-for-Audio/PRD3NJFROMQSL5FYou don't need to get them from these guys but it gives you an idea of what can be done.
Banana Plugs - Page 1
Forum section: electronics / beginners

author: caravanphil
author_rank: Newbie
timestamp: January 31, 2018, 06:39:04 pm
content: Hi everyone,sorry if this is a silly question, or in the wrong place. I am trying to repair a piece of test equipment that has banana plugs. One of the wires has come out and I can't work out if it is possible to take the banana plug apart to reattach the wire or if it is a throwaway item. It does not appear to have been soldered and I can't see any screws to secure it. If it was crimped I can't see how the plastic insulator was attached over itPhoto attached - any help appreciated

author: Cliff Matthews
author_rank: Unknown
timestamp: January 31, 2018, 06:50:52 pm
content: Poke open that round side plastic piece, you may find a set-screw inside (sometimes called a grub screw).

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: January 31, 2018, 06:59:40 pm
content: The elastic plastic jacketing can be pulled back to the wire side. You need to widen it (wiggle it out) where the metal plug comes out of the jacketing.Here is a photo that might help you:The metal parts are inserted backwards in this picture, the square part is what grabs onto the plastic part.

author: caravanphil
author_rank: Newbie
timestamp: January 31, 2018, 07:12:34 pm
content: Thanks for the replies. Done it !!
band stop filter with single supply . - Page 1
Forum section: electronics / beginners

author: basantab
author_rank: Contributor
timestamp: December 04, 2018, 04:11:19 am
content: HelloI had this simple band stop filter schematic and modified to work (supposedly) with single supply by putting 1.5 volt offset .Except that it doesnot work.Is that correct way of offsetting the final stage ?In simulation too it does not work if i input offset voltage of 1 volt and 1 volt peak to peak signal riding on it.It works in simulation it works if i put any voltage without offset.In reality it doesnot work with offset voltage input.Idea is not to get inverting voltage (negative) from final stage so adding offset i thought might bring voltage up above the ground..Is there anything more i should look into ?(also i have been playing around with other types of config like twin-t notch and other active filter)thankyou

author: Circlotron
author_rank: Super Contributor
timestamp: December 04, 2018, 04:32:34 am
content: I think the 1.5 volt bias going into the last opamp is the wrong polarity.Also, the bottom of the input resistor on the lower opamp should go to +1.5V, not ground.Further, I think you have created a band stop filter, not a band pass.

author: basantab
author_rank: Contributor
timestamp: December 04, 2018, 04:44:58 am
content: thanks my bad i wanted to say bandstop filterand last part of opamp is summing amplifier(modified) so that the output is not negative ..I donot know if its possible that way to modify.but i will check with the polarity again thankyou.and regarding earlier stage opamps they are just a voltage follower so is that high pass section requires offset also? (due to cap blocking dc offset and ac passing and single supply cannot buffer ac)?thankyou

author: Circlotron
author_rank: Super Contributor
timestamp: December 04, 2018, 06:43:16 am
content: Quote from: basantab on December 04, 2018, 04:44:58 amYes.
Bandpass for VU. - Page 1
Forum section: electronics / beginners

author: neo
author_rank: Super Contributor
timestamp: August 25, 2017, 05:29:46 am
content: First off, accuracy is not the goal. Pretty lights are the goal, and with pretty lights in mind would the below circuit in conjunction with an lm3916 work in a relative sense?

author: danadak
author_rank: Super Contributor
timestamp: August 25, 2017, 10:47:48 am
content: You will have poor frequency band resolution. And of course signal loss.Attached a sim, you can play with values to control the response.There are 4 channel switched capacitor filters -http://www.newark.com/c/semiconductors-ics/filters-active/switched-capacitor-filters?DM_PersistentCookieCreated=trueYou could do it via FFT -http://mikami.a.la9.jp/meiji/b3/AN42877_12.pdfhttps://community.cypress.com/thread/28886Regards, Dana.

author: neo
author_rank: Super Contributor
timestamp: August 25, 2017, 03:36:48 pm
content: Thank you but the math makes my head spin.

author: drussell
author_rank: Super Contributor
timestamp: August 25, 2017, 03:47:43 pm
content: You should at least be changing the capacitor values in each band so you don't end up with silly values like 7.6 meg.If you get the outputs from each band to be reasonably close, you should be able to trim it so each LM3916 shows the proper level with a (same amplitude, different frequency) test signal in each band and make a reasonable looking "spectral analyzer".Personally, I would do it with active filters for the filters. It would only take a few op-amps to be able to make the filters much, much, much better....

author: neo
author_rank: Super Contributor
timestamp: August 25, 2017, 04:22:57 pm
content: Quote from: drussell on August 25, 2017, 03:47:43 pmI got a better idea, use the MSGEQ7 with a different display, if i could get it to work. Also those values were spit out by calculator, as i said i cannot get my head around the math.

author: Audioguru
author_rank: Super Contributor
timestamp: August 25, 2017, 11:55:54 pm
content: Your filters are very poor, an RC as a highpass and an RC as a lowpass that affect each other and have very gradual slopes.You said "an LM3916" but you needfourLM3916 ICs with one bandpass filter at each IC's input.

author: neo
author_rank: Super Contributor
timestamp: August 26, 2017, 03:42:51 am
content: Quote from: Audioguru on August 25, 2017, 11:55:54 pmI meant an lm3916 per filter, thank you for noticing and they are poor, their also as far as my math skills will take me in the world of bandpass filters.
Bandpass question? - Page 1
Forum section: electronics / beginners

author: nick.sek
author_rank: Regular Contributor
timestamp: June 27, 2012, 07:01:00 pm
content: if you have multiple signals aka bass mid and treble - how to do amplify them after? can they all be amplified through a single op amp - after they have been filtered? or do I just connect them all at the end of to amplify them - as I am design a basic audio amplifier based around the 741 and I'm just have a harder time I'll post my schematic by tomorrow. And the audio input does it have to be passed through a capacitor?thanks nick

author: T4P
author_rank: Super Contributor
timestamp: June 27, 2012, 07:26:29 pm
content: The filter section of an opamp is always in the feedback loop, if you want to think the voltage hasn't got much gain,strap another opamp on the output of the first opamp

author: Simon
author_rank: Unknown
timestamp: June 29, 2012, 09:21:59 pm
content: Quote from: nick.sek on June 27, 2012, 07:01:00 pmThat might be where you need to stop and rethink, the 741 is not going to be great
Bandwidth Calculation: Caveats! - Page 1
Forum section: electronics / beginners

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 25, 2015, 04:45:08 am
content: Some threads ago, there was confusion over what the proper way to measure oscilloscope bandwidth is.There's a rule of thumb:BW = 0.35 / t_rIf t_r is in us, then BW is in MHz, etc.Butthis only applies when the applied waveform is an ideal step, and only when the passband characteristic is nearly linear phase!When the response is peaked (rather than falling off gradually, as a Bessel filter does), the risetime doesn't actually change much (though there is much more ringing present, obscuring it), but the bandwidth can be extended more than double.Here's a recent example I cooked up (in simulation, at the moment). The circuit which generated the waveform is a crude model of a distributed amplifier (4 stages). This circuit uses a chain of inductors to harness the amplifying devices' capacitance as a lumped transmission line: the devices act in parallel at low frequency, but additively at high frequency. Whereas a single stage might do 10MHz (or any number of devices wired directly in parallel), the total achieves over 30MHz.Top: AC small signal response (frequency)Bottom: Time domain step responseThe passband is +/-1dB up to 34MHz, and cutoff (-3dB) at 36MHz.But the rise time is only 15ns, which implies a bandwidth of 0.35 / 0.015 = 23MHz.If I tested this circuit with an impulse, I would observe slightly lower risetime. A simpler circuit (with not as sharp a cutoff) would show a much more exaggerated response.So don't do step response testing with waveforms other than step, because that's a necessary part of it being a step response test! And if the time domain response isn't perfectly gentle and well-behaved, expect to get dubious results using that old rule of thumb.That's why rules of thumb are not theorems or laws!But

author: nbritton
author_rank: Frequent Contributor
timestamp: November 25, 2015, 08:51:12 am
content: http://m.eet.com/media/1140862/19209-263113.pdf
Barcode not able to scan, arduino, Adafruit_Thermal library - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: September 27, 2019, 07:54:07 am
content: I am using latest Adafruit_Thermal library, arduino mega 2560 & using it to print barcode. Issue is barcode is printed but my mobile app is unable read it. tried multiple apps also, but not reading.Attached is code & output print.I have tried almost all opotions in adafruit lib like CODE39, CODE93 & others, all gets pritned but not able to scan.need to print digits only 0 to 9 only. In image attached, top part is removed it had customer info.Text is printed correctly no issues.Code:void print_barcode(uint16_t g_serial_number){uint8_t temp1;uint16_t temp;char_t barcode_str;char_t serial_number_bytes = {' ', ' ', ' ', ' ', ' '};temp = g_serial_number;temp1 = temp % 10U;serial_number_bytes = temp1 | 0x30U;temp = temp / 10U;temp1 = temp % 10U;serial_number_bytes = temp1 | 0x30U;temp = temp / 10U;temp1 = temp % 10U;serial_number_bytes = temp1 | 0x30U;temp = temp / 10U;temp1 = temp % 10U;serial_number_bytes = temp1 | 0x30U;temp = temp / 10U;temp1 = temp % 10U;serial_number_bytes = temp1 | 0x30U;for(cnt = 0; cnt < 8U ; cnt++) // fill with zeros{barcode_str = '0';}for(cnt = 0; cnt < 5U ; cnt++){barcode_str[cnt+8] = serial_number_bytes;}barcode_str = '\0';printer.setBarcodeHeight(19);printer.printBarcode(&barcode_str, CODE39);Serial1.write(14); //move to next label}

author: sleemanj
author_rank: Super Contributor
timestamp: September 27, 2019, 07:59:53 am
content: Make it taller, try with less data. Maybe you can use a QR
barcode scaner burned! - Page 1
Forum section: electronics / beginners

author: oskimac
author_rank: Contributor
timestamp: July 23, 2020, 04:49:57 am
content: help. i have two identical barcode scanner with the same chip completely burned. i identify some of the pins , can someone help me find a replace?

author: james_s
author_rank: Super Contributor
timestamp: July 23, 2020, 05:02:09 am
content: It's a buck regulator IC, I don't know precisely which one but if you can identify the package style (SC70?) you should be able to use the parametic search on digkey, mouser, etc to find something that will work.

author: oskimac
author_rank: Contributor
timestamp: July 23, 2020, 05:08:25 am
content: i suspect it to be sot23-5 but there are nothing left of him!seems likehttps://datasheet.lcsc.com/szlcsc/SY8089AAAC_C78988.pdf

author: james_s
author_rank: Super Contributor
timestamp: July 23, 2020, 06:50:20 am
content: What model is the barcode scanner? Maybe somebody has one that isn't burned?

author: oskimac
author_rank: Contributor
timestamp: July 23, 2020, 12:27:11 pm
content: Zebex Z-6030https://es.aliexpress.com/item/32807608757.html

author: amyk
author_rank: Super Contributor
timestamp: July 24, 2020, 12:20:42 am
content: If this happened to two of them, I would check the power supply to make sure its output is not too high.

author: oskimac
author_rank: Contributor
timestamp: July 24, 2020, 05:55:56 pm
content: yes. of course it was one thing to do.

author: oskimac
author_rank: Contributor
timestamp: July 24, 2020, 06:00:40 pm
content: i give up on them. since i find a dead short all the way up to the micro... and after apply 1.8 and 3.3 volt on the pads i figured it was the output of the buck regulator my thermal camera shows only the micro to gets hot.i was trying to repair them because they are expensive here.300+ usd
Bare 3 phase bus bars....what isolated voltage is safe? - Page 1
Forum section: electronics / beginners

author: opampsmoker
author_rank: Regular Contributor
timestamp: December 11, 2020, 02:00:04 pm
content: Hi,We will have isolated, bare, three phase bus bars. Fully Mains transformer isolated. (mains input is 240VAC phase to neutral)We're going to step down the 3 phase mains to the bus bars.What is the highest VAC level that these bare bus bars can be at and not be a danger to humans touching them?(ie touching one bus bar, and also touching between two bus bars with each hand)

author: Siwastaja
author_rank: Super Contributor
timestamp: December 11, 2020, 02:06:48 pm
content: Approx 50VAC between phases. Exact value depends on jurisdiction, i.e., a function of location and time.

author: mag_therm
author_rank: Frequent Contributor
timestamp: December 11, 2020, 03:17:11 pm
content: You would also have to consider the arc flash, related to the fault level.That can happen when an operator drops a tool for example.Or puts his meter probes across the bus and the meter explodes ( I saw that more than once, fortunately without injury!)Is the "British Standard Finger" still used?I used them on cabinetry/bus covers of the big rectifiers.

author: Jeroen3
author_rank: Super Contributor
timestamp: December 11, 2020, 03:34:17 pm
content: Galvanic isolation is only a safety feature when you use it in conjunction with insulation monitoring.Bare busbars are common in switchboards or distribution rooms.There are some products available (eg: rittal) that insulate then minimally, to reduce the risks.But the answer to your question is ELV:https://en.wikipedia.org/wiki/Extra-low_voltage
Bare lcd signal? - Page 1
Forum section: electronics / beginners

author: frenky
author_rank: Unknown
timestamp: January 15, 2013, 09:41:03 pm
content: Hi guys.I'm trying to put big 7 segment display on the kitchen scale that currently has small numeric LCD.I was hoping that I could catch the value going to the eeprom but sadly it doesn't use eeprom during measurement.So the only way to get the value is to read data from LCD pins.LCD has 4 digits, 3 dots and some other signs (battery low + 2 other)It uses 14 pins. One is ground and the other 13 have some odd signal (picture below).I'm sure it's not odd for you guys so please point me into the right direction on how to decode this signals.Wave form and kitchen scale below:

author: Bored@Work
author_rank: Super Contributor
timestamp: January 15, 2013, 11:16:52 pm
content: Thishttp://www.atmel.com/Images/doc2530.pdfdescribes among other things how such LCD glasses are driven.

author: frenky
author_rank: Unknown
timestamp: January 15, 2013, 11:18:48 pm
content: TnxI have also found something that helps:http://www.nxp.com/documents/data_sheet/PCF8576C.pdf