hybridfree/eevblog-posts huggingface dataset:
Two SP-150-24 in parallel? - Page 1
Forum section: electronics / beginners

author: gcardinal
author_rank: Unknown
timestamp: April 30, 2016, 11:35:45 am
content: I have around 10 units ofSP-150-24power supplies from Mean Well - all brand new.For most 3D printers and CNC 6A is not sufficient, however > 10A would be perfect for most application.After checking info on Mean Well website there is no support for parallel connection on this series of PSU.So I was thinking if it would be possible to solve this with a beefier rectifier diode on each PSU, something likePX1500K? Or is there any other solution to utilize both PSU at ones?..

author: danadak
author_rank: Super Contributor
timestamp: April 30, 2016, 11:45:06 am
content: Here is a general discussion.http://electronics.stackexchange.com/questions/154127/connecting-two-power-supplies-with-same-voltage-rating-to-increase-current-outpuYou could design an external circuit to force sharing, but thats not plug andplay, like a supply designed for sharing.Regards, Dana.

author: gcardinal
author_rank: Unknown
timestamp: April 30, 2016, 11:50:11 am
content: Quote from: danadak on April 30, 2016, 11:45:06 amThank you, Dana! I was hopping for a more "in-line" solution.How about a:Wirewound resistor 4.7 Ohm 100 Wafter a rectifier diode on each PSU ?

author: danadak
author_rank: Super Contributor
timestamp: April 30, 2016, 07:12:21 pm
content: What you sacrifice is V regulation, but yes that will help.And of course equal powersharing out the window because of mismatches. Although as you raise the value ofR the more it becomes a current source. But raising R is burning power which inturn is meting the ice cap........Regards, Dana.

author: SeanB
author_rank: Super Contributor
timestamp: May 01, 2016, 10:55:10 am
content: Not possible to split the loading between the supplies? One does half the motors and the other the rest, or one handles the motors and the other the bed heating and the electronics. You just need to common the negative connection on both to the board common for this to work.

author: danadak
author_rank: Super Contributor
timestamp: May 01, 2016, 11:32:02 pm
content: I would recommend you spend some time with a sim to establish the performanceyou would like to see. Here is an example, worst case stats were done of changingR1 and R2 values. I would posit the Vth of the diodes, variation, temp effect, wouldbe a greater problem, that too you can sim.Regards, Dana.
Two-state circuit / inverter on higher voltages - Page 1
Forum section: electronics / beginners

author: mihai
author_rank: Newbie
timestamp: May 17, 2017, 03:50:49 pm
content: Hi everyone! I would need to construct something like a digital inverter ic but on different voltage levels (not TTL). My aim is to take the inverse of the electric signal on a wire transferring voltages in two states: 48V and 0V. I would greatly appreciate if you could recommend me some implementations or sources where to do research in the topic.Thank you in advance!

author: danadak
author_rank: Super Contributor
timestamp: May 17, 2017, 09:11:35 pm
content: Can you be a little more descriptive, its not clear what you are trying to do.1) Take 0 and convert it to 48, and 48 to 0 ?2) Take 48 and convert it to -48 ?3) Interface the state of the line to what voltage domain ?4) is this a 4-20 mA current loop application ? A telco application ?Just guessing......Regards, Dana.

author: mihai
author_rank: Newbie
timestamp: May 20, 2017, 05:04:33 pm
content: Hello! Thank you for your answer.The basic problem is that I possess a switch that opens the circuit if pushed (while I would need the opposite). It opens/closes 48V. The replacement of the switch is not really an option so I was wondering how to overcome this problem. That's when a basic digital inverter's principle of operation came to my mind. So I would need something like that, changing low (close to zero) voltage levels to 48V and vice-versa.Thank you in advance for your help!

author: MagicSmoker
author_rank: Super Contributor
timestamp: May 20, 2017, 05:14:16 pm
content: The very simplest and most robust solution is to have the switch operate the coil of a 48V/SPDT relay. You could also make an inverter out of two transistors and a resistor or two, but why make this any more complicated than necessary?
Two state push button where to buy? - Page 1
Forum section: electronics / beginners

author: tintin
author_rank: Newbie
timestamp: September 28, 2013, 06:03:04 pm
content: HiI'm looking for a two state push button. Where one contact will be activated when button is pushed a little bit and both contacts activated when button is pushed to the bottom. Like a shutter button in a camera.Anyone know where I can find one?

author: andtfoot
author_rank: Unknown
timestamp: September 28, 2013, 07:28:15 pm
content: If you can't find one to buy, you might be able to make something by offsetting 2 switches like this:http://martybugs.net/photography/remote.cgi

author: JeanF
author_rank: Regular Contributor
timestamp: September 28, 2013, 07:34:12 pm
content: Hi,if you search for "double action" you'll get some results, here are the first I got, there are probably many more sources (if you find a manufacturer product page such as the 1st and 2nd links look for the part number on your favorite distributor : RS, farnell, digikey...)http://www.nh-technology.de/en_double_action.phphttp://www.alps.com/WebObjects/catalog.woa/E/HTML/Tact/SurfaceMount/SurfaceMount_list1.htmlhttp://uk.farnell.com/jsp/search/browse.jsp;jsessionid=URFIQAYJ50THUCQLCIQZMMQ?N=0&Ntk=gensearch&Ntt=tactile+double+action&Ntx=mode+matchallpartial&exposeLevel2Refinement=true&suggestions=false&ref=globalsearch&_requestid=595600cheers

author: tintin
author_rank: Newbie
timestamp: October 07, 2013, 06:22:20 pm
content: Thank you! Exactly what I'm looking for!
Need Help! Two Step Constant Voltage, Current Limited Charger - Page 1
Forum section: electronics / beginners

author: waqas
author_rank: Newbie
timestamp: May 10, 2022, 04:09:53 pm
content: Hi Guys. I want to build this charger circuit. But i want to knowhow to calculate the values of R2, R6, and RS?I calculated the values of RISW = 12ohm to turn Q2 transistor on at 50mA, and R3 = 0.2ohm to limit Max current to 3A.I want to use bulk charge at 14.4V and then float charge to 13.6V.Looking forward for good response.Waqas

author: waqas
author_rank: Newbie
timestamp: May 10, 2022, 05:23:33 pm
content: No help from experts? waiting for reply

author: waqas
author_rank: Newbie
timestamp: May 11, 2022, 01:04:53 am
content: 77 views, not a single reply

author: waqas
author_rank: Newbie
timestamp: May 11, 2022, 02:57:55 pm
content: No one can answer my question?

author: magic
author_rank: Super Contributor
timestamp: May 11, 2022, 04:49:07 pm
content: There are no experts here, only posers.Quote from: waqas on May 11, 2022, 02:57:55 pmThat may actually well be the case, as you have posted some weird circuit doing some weird things without much explanation.Others may be put off by your constant whiningI suppose the way it's meant to work is that at high charging current, Q2 turns on and passes current through D3. Then R6 pulls up the ADJ voltage seen by LM317 and thus increases its output voltage. So R6 will determine how much the voltage increases during charging - less resistance is more boost.R2 is in parallel with RS so it could be just one resistor. It determines "float" voltage. You will get ~2V for each 240Ω here, so maybe ~1.5kΩ is a good starting point for tuning.I suppose D2 is some sort of thermal compensation, it should probably be kept at similar temperature as the battery.
Two Step Down Transformers -> One Inverter - Page 1
Forum section: electronics / beginners

author: Oscar7
author_rank: Newbie
timestamp: August 09, 2024, 05:28:49 pm
content: I have a 6kw 48v PSW stand alone inverter with AC output of 240V. This is connected to a 3kw step down transformer (240V to 120V). Works fine, powers all our appliances. (Note all our appliances are 110 -120V).We have another identical (same brand, size, specs) 3kw step down transformer. I would like to connect both step down transformers to the same source inverter, don't see an issue here, maybe not sure. But I also want to join the Neutrals on the output of both transformers. I am thinking for the main panel to have both neutrals of each transformer on the same bar, and using the Line (hot) from 1 transformer to power one side of the main panel, and the 2nd transformer to power the other side of the main panel. There will be no 220V loads, that will try to draw from both transformers at the same time (not sure if that would work even if we did).Or can the output of both transformers be connected in parallel ?? This option I am more uncertain of.I got this inverter from someone , think they ordered it in error. Hence the need for the step down transformers.Please share your thoughts on using the the two transformers !

author: Xena E
author_rank: Frequent Contributor
timestamp: August 09, 2024, 06:59:19 pm
content: Edit: The inverter may dislike being asked to push inrush current into these transformers.To parallel the transformers they will need to be identical and in phase, out of phase and you will cause them to short circuit each other.To confirm the correct phasing:Connect what you consider are the neutrals of each transformer, then measure the voltage between the line connections. If the voltage is 220, the transformers are out of phase and should not be parallel connected.If the voltage is zero, then this is the connection that can be parallel.Don't assume the manufacturer got any colour coding or marking scheme the same.If your transformers each have single output windings, ground reference the side of the winding that you nominate as 'neutral'.It is perhaps safer to have the transformers in phase, but still keep the two line connections as separate circuits.Always use a GFI/RCD.Take care to follow local codes and regulations regarding electrical safety.RegardsX
two switching power supplies connected together - Page 1
Forum section: electronics / beginners

author: cosminnci
author_rank: Regular Contributor
timestamp: February 18, 2015, 08:48:02 am
content: I have a circuit with an optical isolation, one side powered form a switching power supply and one through a usb from pc.the middle piece is ft232rlwhen connected so the ftdi chip is not recognizedwhen I power the circuit from a battery all works great.so I suppose there is something happening with the power from the 2 supplies the one from pc and the switching one, in combination with the optical isolation.what could be the cause?thank you,regards,Cosmin

author: Stephen37
author_rank: Contributor
timestamp: February 18, 2015, 12:30:52 pm
content: You need to power everything from a single power supply or use optocoupler + power transistor on the other side if you want to drive something that requires another power supply.The PC side with the USB should work fine and power an optocoupler.

author: cosminnci
author_rank: Regular Contributor
timestamp: February 20, 2015, 07:47:21 am
content: I use it for i2c communication, the usb powers an ftdi chip, but when there is noise from ac especially fluorescent bulbs the ftdi resets.when I power one of them from battery all works fine.

author: tautech
author_rank: Super Contributor
timestamp: February 20, 2015, 10:03:46 am
content: Check the ripple from the SMPS supply AT the chip it powers.Being SMPS a scope will be needed to see it at those frequencies, probably ~40 KHzSome can have some horrendus ripple and if this value on top of the DC value is close to a threshold mayhem ensues.Some extra bulk capacitance on that rail and a inductor in series should get the ripple under control.
two transistor flasher circuit - reverse engineering - Page 1
Forum section: electronics / beginners

author: armandine2
author_rank: Frequent Contributor
timestamp: July 06, 2024, 01:00:36 pm
content: I have recently drawn out a simple printed circuit board, to understand an old Uniross Ni-Cd rechargeable torch.I have recreated the flasher circuit onto a breadboard and connected it to the torch head - where it flashes about once a second, with the pcb disconnected.However, trying this breadboard circuit with apparently similar bulbs I have it just lights the bulb without flashing.At first I thought I wonder if the torch head - which is glued together and likely difficult to disassemble - has another component inside. Or is the circuit quite well designed to the bulb's resistance?I have as yet  figured out the circuit's operation - any ideas?

author: ledtester
author_rank: Super Contributor
timestamp: July 06, 2024, 02:40:32 pm
content: Quote from: armandine2 on July 06, 2024, 01:00:36 pmHere is a Falstad simulation:(Falstad simulation)The bulb is represented by the 10R resistor. To speed things up I used a 1uF cap.The circuit seems to be sensitive to the bulb's resistance. At 20R it doesn't oscillate anymore.

author: armandine2
author_rank: Frequent Contributor
timestamp: July 06, 2024, 04:18:42 pm
content: The original bulb was measured at 1.0 ohm - I don't think the other bulb I measured was a great deal more, but enough I guess.

author: tooki
author_rank: Super Contributor
timestamp: July 06, 2024, 06:26:31 pm
content: Quote from: armandine2 on July 06, 2024, 04:18:42 pmThe cold resistance of a bulb is much lower than once hot. In Falstad, you can actually place an incandescent lamp (not sure why ledtester didn’t just do that, actually), and you can see its resistance change as it heats up. If I set it to a 3V, 1W lamp, then it starts with a cold resistance of 0.45 ohms and settles in at 9 ohms, just like Ohm’s law would predict.

author: Konkedout
author_rank: Frequent Contributor
timestamp: July 08, 2024, 04:58:45 am
content: That circuit looks like it can probably work. But I wonder about one or two diodes in the pcb layout which I do not see in the schematic?If you had >4V or so you could use a white LED. That would probably require a low value resistor in series and maybe also a high value resistor in parallel.

author: armandine2
author_rank: Frequent Contributor
timestamp: July 08, 2024, 06:22:50 am
content: The two wires on the left hand side go to the charger socket - the diodes isolate the charger circuit from the light on and flasher circuits.
Two voltage regulators - Page 1
Forum section: electronics / beginners

author: Spekkio
author_rank: Regular Contributor
timestamp: April 30, 2011, 03:07:54 pm
content: Can there be a problem having two voltage regulators in one circuit?I have a 7805 and a LD33CV. This is not permanent though, in the future I'm going to use only 3.3v

author: david77
author_rank: Frequent Contributor
timestamp: April 30, 2011, 03:10:52 pm
content: I think to answer your question we'd need more details. Can you post a circuit diagram?

author: Simon
author_rank: Unknown
timestamp: April 30, 2011, 03:16:22 pm
content: yes, what are you doing with them, are you trying to connect them in parallel ?I'm guessing you have a 5V and a 3.3V driven off it ? that is fine but do remember that the 5V one must be able to take the current for both 5V and 3.3V. If you have a low current requirement of the 3.3V and are dropping to 5V from a high voltage like 12v I'd suggest separating them to take some thermal load off the 5V one unless of course it is well over speced and maybe your trying to get very stable 3.3V

author: Simon
author_rank: Unknown
timestamp: April 30, 2011, 09:05:24 pm
content: then fire away, no problems there, just make sure they both have their own decoupling capacitors

author: Zero999
author_rank: Super Contributor
timestamp: April 30, 2011, 09:05:35 pm
content: Care to mention how much current is required?For optimal battery life use a low drop-out regulator for 5V. The 3.3V regulator can be a standard LM317 because the drop-out isn't important.

author: Spekkio
author_rank: Regular Contributor
timestamp: April 30, 2011, 09:06:30 pm
content: they are connected in parallell to a 9v battery.yes, because after I connected the 3.3V regulator, it seems like the 5v regulator is getting warmer than usual.or maybe just my imagination, maybe I never touched them before I connected the 3.3V reg, dont remember

author: Simon
author_rank: Unknown
timestamp: April 30, 2011, 09:08:25 pm
content: it will have no affect unless the 3.3V part of your circuit affects consumption on the 5V part
Tying power rails in series - Page 1
Forum section: electronics / beginners

author: stevetob67
author_rank: Contributor
timestamp: September 10, 2020, 01:21:47 pm
content: I have a 460 watt HP Server Power Supply and purchased an adaptor board for it that gives me 12 x 12 volt power outlets.My question is, if I used Diodes or MOSFET's, could I tie two or more outlets together in series to achieve a higher voltage without sacrificing amperage? Or is there a better way of achieving this?Thank you in advance for any help or advice given, much appreciated.Steve

author: JuanGg
author_rank: Regular Contributor
timestamp: September 10, 2020, 02:33:09 pm
content: For you to be able to tie them in series, they would have to be isolated from each other, i.e. not have a common ground which is likely the case. You should check the specs of your particular power supply.There is no easy way to do what you want with only diodes or mosfets. You could feed those 12 V to a DC to DC converter to get the voltage you want. Depending on what you want to do, it may be worth it to look at another power supply.Juan

author: Nusa
author_rank: Super Contributor
timestamp: September 10, 2020, 03:46:53 pm
content: Almost certainly not, so far as the outlets from a single supply are concerned.A DC-DC converter would be the way to go, if you don't need too much current. If you need a lot, cheaper to just buy the right voltage supply in the first place.In the past I have taken TWO 500 watt 12V Dell Server Power Supplies and put them in series to get 24V. I had to partially disassemble one of them to isolate the DC ground from the chassis ground to accomplish that.

author: stevetob67
author_rank: Contributor
timestamp: September 11, 2020, 11:15:08 pm
content: Thank you both for your replies, I thought that this would be the case but there is no harm in asking.I will just go with the other option I have of putting two identical 24 volt transformers in series so I can still get the 6 amps that they are rated for but achieve the minimum 48 volts I need.Again thank you for your time.
Type of GSM RF Connector? Possibly MMCX?  - Page 1
Forum section: electronics / beginners

author: elliottveares
author_rank: Contributor
timestamp: July 26, 2015, 12:47:30 am
content: Hi everyone for who is reading this. I am in the UK and I have an intruder alarm panel which is cellular/GPRS enabled that has a 3G GSM antenna. The alarm panel is inside a cupboard and the cable of the supplied antenna is only about 20cm long and thus no GSM signal is received by the panel due to it being in a enclosed cupboard along with the added effect of living in a rural area.Thus I essentially need to by an external 3G GSM antenna what has a cable length of about 5 meters. The thing is I don't recognize the type of RF connector and thus need to make sure that the external antenna that I buy has the right connector type. The connector is a push fit type and while it looks like MMCX type connector from my own research, I am not 100% sure.The square base part of the connector is about 3.62mm wide and the round bit at the end of the connector is about 2.38mm in diameter. Pictures below.Regards: Elliott (of Grotto Tree)

author: gaijin
author_rank: Contributor
timestamp: July 26, 2015, 01:37:08 am
content: looks like a MMCX I have a few cables around and the diameter of the connector is about 2.4mm.The square base on a right angle is about 3.6mm for my connectors.
Types of capacitors - Page 1
Forum section: electronics / beginners

author: electronics-whiz
author_rank: Regular Contributor
timestamp: May 29, 2015, 05:05:01 pm
content: I know some of the capacitor types, but others I'm still not sure just looking at them.I can tell an electroletic, supercap, ceramic disks, tantalum caps.I'm not sure though about the plastic rectangular/box looking ones. I know there not electrolytic as are not marked and found in AC input stages. Then there are ones that are also rectangular but are like plastic coated and have curved edges. I always called both these Mylar caps, but I'm not not sure that is right as I can't see why they'd use a different case style.Am I right, if not what are these capacitors?

author: TimFox
author_rank: Super Contributor
timestamp: May 29, 2015, 05:19:26 pm
content: You probably mean plastic-film capacitors.There are two common types of film, with a few others.1. Polyester or PET: Mylar is a trademark. Reasonable performance (Q roughly 100 to 200).2. Polypropylene: Excellent performance (Q roughly 1000). Tends to be larger than polyester for same capacitance.Most film capacitors now are metallized film: very thin metal deposited directly on both sides of thin plastic.Film-foil capacitors have actual metal foil separated by film, for lower ESR, with increased size.

author: tggzzz
author_rank: Super Contributor
timestamp: May 29, 2015, 06:18:05 pm
content: Have a look athttp://eevblog.com/files/seekPDF.pdf
types of optocoupler / optoisolator - understanding them - Page 1
Forum section: electronics / beginners

author: pedake
author_rank: Contributor
timestamp: September 28, 2015, 03:07:12 pm
content: OPTOCOUPLER PROBLEMI was playing around with different optocouplers yesterday.PC123http://www.sharpsme.com/download/pc123-epdfMOC3051http://www.datasheets.pl/optocoupler/MOC3051.pdfI understand that one is a random phase and the other a zero crossing (is that right?)Attached I captured the characteristics.I am absolutely ignorant of the hows here. But my guess was: The zero crossing will only show a sharp drop after it crossed zero from the top (however that would work with a simple IR LED). But no... I tried my cheap-ass FuncGen and: same behavior.Now:How do they work, exactly? ( not the principle. that I understand, of course)Why does the PC123 discharge like a cap?Why does the MOC3051 follow the input so nicely?What type of other optocouplers are there?I tried finding some literature online, of course. And I am packing for the next trip :-/ I will not have my books for a few daysI am taking my DSO though :-) I want to try to get it running with my own software (based on DSO-USB-Tool) for the Hantek / Tekway / Voltcraft cheapies.Of course I put a big fat 1M resistor there...Maybe someone can provide me a link to a comprehensive explanation for the different types of otptocouplers. The light stuff... "optoisolators for total morons"-level.EDIT:Thanks, KilrahBJT transistor characteristics...http://ecee.colorado.edu/~bart/book/book/chapter5/ch5_6.htm#topThanks and good week to all

author: Kilrah
author_rank: Unknown
timestamp: September 28, 2015, 03:28:19 pm
content: Instead of looking for "different types of optocouplers" you should rather look up the different types of transistors and other switching devices like the simple bipolar transistor that is in the PC123 and the triac you find in the MOC3051.What I mean is that an optocoupler is typically just that bog standard transistor/switching semiconductor, but that is switched by a light beam instead of the usual electrical connection, so the generic behavior of that particular device applies.Also, would be good to see what circuit you had, captures mean nothing when we don't know what you wired and what you were measuring.The triac (look it up) is typically used to switch AC, and turns off whenthe AC it switches crosses zeroandthe control signal is absent. It seems you're talking of a zero crossing of your LED supply which obviously is something else.

author: pedake
author_rank: Contributor
timestamp: September 28, 2015, 04:21:36 pm
content: KilrahVery helpful, thank you!http://ecee.colorado.edu/~bart/book/book/chapter5/ch5_6.htm#topI was never aware that BJT have a capacitance. It does, of course, absolutely make sense now.I feel a little dumb now
Typical Electrolytic capacitor current rating - Page 1
Forum section: electronics / beginners

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: September 09, 2018, 02:34:28 pm
content: If I take a typical electrolytic capacitor say 100uF , 160V. I charge it to 100V DC. And then discharge it through a 3.3 ohm resistor. Would the peak current in the resistor be 33.33A ?Is it practically possible for the electrolytic capacitor to source this amount of current for small period of time?

author: helius
author_rank: Super Contributor
timestamp: September 09, 2018, 03:24:24 pm
content: Quote from: ZeroResistance on September 09, 2018, 02:34:28 pmThere appears to be a problem with your arithmetic. 100V divided by 3.3Ω is 30.30A, not 33.33. So the answer would be no.Additionally, this is only the case for idealized components. In any real circuit, the capacitor has ESR (series resistance), which limits its current capacity, and wires have inductance, which limits the derivative of the current (you cannot go from 0 A directly to 30).QuoteThis is a different question. If discharged through a (approximately) 0 ohm wire, the peak current through an elco can be higher than that. It may cause damage to the capacitor's plates if it is too high or repeated too fast. You may need to conduct tests to see how hard you can abuse a capacitor before it dies; the data sheets are intended for more typical applications, where the capacitor is charged and discharged at 120 Hz, and specify the maximum current capacity at this frequency (the rated "ripple current"). A typical ripple rating for a 100 uF cap would be 1 to 2 A RMS.The data sheets may give you the ESR, or express it in terms of dissipation factor or tan ø. You can calculate the ESR from the DF as follows: \$ ESR = {DF \over 2 \pi f C} \$, where f is the frequency in hertz and C is the capacitance in farads.

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: September 09, 2018, 05:31:19 pm
content: Quote from: helius on September 09, 2018, 03:24:24 pmMany thanks for the answer.So the effective resistance with limit the max current and inductance will limit the rate of rise of current right?.So if the esr of the Cap was 0.7 ohms. That would make the total resistance 4ohm. So that would make it 25A peak right.But you also have said that rms current of a electrolytic cap is around 2A rms.So would that mean that eletrolytic caps are not meant to be used in this kind of application and only strobe or flash capacitors should be used.

author: helius
author_rank: Super Contributor
timestamp: September 09, 2018, 06:00:55 pm
content: The capacitor may be rated for 2A continuous ripple, but be capable of higher currents if they are not continuous. This is not guaranteed by the datasheet and needs to be tested.
Typical RF Test Plan Sample? - Page 1
Forum section: electronics / beginners

author: nicedwarf
author_rank: Newbie
timestamp: January 24, 2015, 07:16:10 am
content: Hi,I will be working on developing an RF test plan in my new job in the coming months. I'd like to get up to speed by taking a look at a couple of sample RF test plans that might be floating around. Ideally the plan would be typical of what one might use at the test bench or on a production line (requiring multiple steps, maybe loops, delays, pass/fail, etc). Are there any links/samples you all can point me to?Thanks

author: Neganur
author_rank: Unknown
timestamp: January 24, 2015, 08:53:08 am
content: What do you mean, sample test plan. Do you know what you want to test?Try to avoid duplicate posts btw, it's the same forum so I don't think there's a need to have the same discussion in two places.

author: nicedwarf
author_rank: Newbie
timestamp: January 24, 2015, 05:37:23 pm
content: Thanks for the tip.I am comfortable with RF measurement types, but I want to get up to speed on the other use cases that include these measurements when it comes to things like sequencing, inserting delays, pass/fail criteria, error handling, etc. I will be testing primarily RF components used in wireless systems (sensors & wifi).

author: KJDS
author_rank: Super Contributor
timestamp: January 24, 2015, 06:16:07 pm
content: There are three stages, plan, procedure, implement.I'll assume that as you're talking about delays then you're concerned with the coding.The first stage, the plan, will give an overview of what is to be done. for example, it may state that the transmitter is to be tested at both ends of the band and at the middle of the frequency band at maximum power, and that modulation will be be tested mid band for all nine specified power levels. It may also state that every 100th unit is subject to temperature testing.The second stage, the procedure, will detail how it is to be done. This will include test equipment to be used, measurement uncertainty, requirement specification and test limits. The test setup will be described and so on and so forth.The actual implementation will then be carried out and verified to show it is fit for purpose.Now having written all that, what is it that you need to know? The sequencing will usually be set out in the procedure, as will the pass/fail criteiria. Error handling is usually a company specific. A cheap item that will just be thrown away if it fails a test usually just means that the test is ended the moment a first error is found. For more complex equipment a minor fail will usually just be recorded and the rest of the testing is continued to allow more data to be given to whoever has to repair it.
u-blox ZED-F9T and soldering of LGA 54  - Page 1
Forum section: electronics / beginners

author: e-pirate
author_rank: Regular Contributor
timestamp: October 04, 2025, 08:56:31 pm
content: Hi folks.So, okay, I decided to try luck and build a Stratum 1 public NTP server based on u-blox ZED-F9T and I210 SDP port for PPS input.The ZED-F9T claims <5 ns time accuracy when GNSS locked - pretty good. The I210 related stuff is tested (with the help of SRS DS345 DDS generator and some ugly wires) and working as expected.So, I can get to the most difficult part - obtaining a ZED-F9T module. First of all local prices are beyond any reasonable levels. But there are some used modules available on AliExpress. They come with a piece of PCB they we originally soldered to - but I'm fine with that.What I'm more worried about is the casing. Instead of DIY-friendly LEA-F9T that come in 28 pin LCC the ZED-F9T come in LGA 54. Unfortunately, the LEA-F9T does not support GLONASS L2 in favor of GPS L5 and they are even more expensive so I have to stick with ZED-F9T.So, what the LGA 54 and how do I de-solder and then solder it again? I've never seen anything like this before except CPUs. No doubts I will be able to make PCB for that pin pitch at home, but no access to pins disturbs me a lot! On the first glance it looks like a PCB or ceramics of some sort with a soldered shield. I'm worried that is I go with a hot air over it to de-solder/solder, I can damage the module or de-solder shield. Any ideas/experience on how to handle such packages?

author: e-pirate
author_rank: Regular Contributor
timestamp: October 07, 2025, 05:13:09 pm
content: Cause nobody answered my question I found an answer myself. This not ZED-F9T, but close enough:
u current gold rev0.5 - Page 1
Forum section: electronics / beginners

author: pvnshet1
author_rank: Newbie
timestamp: July 28, 2025, 12:04:25 pm
content: Hi, I am facing an issue with Gerber file fabrication. Could you please check and help resolve the problem?Regards,Praveen

author: Psi
author_rank: Super Contributor
timestamp: July 28, 2025, 12:28:05 pm
content: That's to be expected. The design was panelized with special traces coming out of each PCB and onto a panel connector. It allowed the pcbs to be tested as an entire panel all at once.You can either remove those traces, since they don't do anything for a single PCB.Or maybe there's some gerbers available for a non-panel version, dunno.Or you can simply tell the PCB fab that it is ok to ignore that and make it as is.It's perfectly normal that they would query this, it makes no sense to them and look like something is missing.Here's an EEVblog video showing the design and how it was originally panelizedAnd a photo of it
U Current Help  - Page 1
Forum section: electronics / beginners

author: Ranger14
author_rank: Regular Contributor
timestamp: February 28, 2018, 03:37:55 am
content: I am looking at building myself the original U current and want to know if there was a big enough difference to use the U Current Gold vs the OriginalOr is there a better or simpler wayThanks

author: JustMeHere
author_rank: Frequent Contributor
timestamp: February 28, 2018, 04:38:19 am
content: Go for the Gold!
U2008 regulator triac blows up - Page 1
Forum section: electronics / beginners

author: Alana
author_rank: Frequent Contributor
timestamp: January 24, 2022, 10:30:44 am
content: I made a regulator box for my AC loads using U2008 regulator kit.It works fine when i test it with a light bulb but blows up when i connect my vacuum cleaner. Not as soon as i connect load but after like 5-10mins of working at low power setting.At first i used BT139 triac then i replaced it with beefiest triac i could find BTA41. Both blow up with the same faliture - shorted gate to A1.Recently i added a snubber circuit - no luck, another triac blown. Triac is mounted on a radiator in ventilated part of the case.In this configuration it worked fine with smaller vacuum cleaner and circular saw. Motor power 1000W and 700W. Big vacuum cleaner is 1400W and this should be well within even BT139 load current capabilities, but it blows.I suspect there may be something with voltage spikes that kill my triac but I have no means of safely scope it at the moment.Any advice?
U822c lcr for beginner - Page 1
Forum section: electronics / beginners

author: Dlrowdna
author_rank: Contributor
timestamp: October 03, 2020, 02:14:20 pm
content: Hi. Is it worth for buying? Couldnt find any review or feedback on this meter. Why? Bad quality?

author: ledtester
author_rank: Super Contributor
timestamp: October 03, 2020, 03:41:12 pm
content: The DER DE-5000 has been mentioned a lot on these forums.There is also this thread:https://www.eevblog.com/forum/beginners/looking-to-buy-lcr-meter-what-are-you-options-on-brands/msg2876000/#msg2876000

author: Dlrowdna
author_rank: Contributor
timestamp: October 03, 2020, 04:08:22 pm
content: But is it the same device? I'am interesting in u822c lcr meter. De-5000 difficult to buy in our country. Must order from ebay. But I used to aliexpress.

author: MosherIV
author_rank: Super Contributor
timestamp: October 03, 2020, 05:26:47 pm
content: No DE5000 is different device to u822c.I seem to remember Dave has a u822 and he even got sent the new c version.

author: Dlrowdna
author_rank: Contributor
timestamp: October 03, 2020, 07:48:07 pm
content: It is a pity that he do not share his opinion about this device.

author: MosherIV
author_rank: Super Contributor
timestamp: October 04, 2020, 12:12:58 am
content: Sorry, I got it wrong, Dave has the u1733 and he reviewed that.They do look similar.https://www.eevblog.com/2012/01/14/eevblog-234-agilent-u1733c-lcr-meter-teardown/Edit: watching the video and checking search, looks like a rebadge of the early escort design based on the image search.I got one branded Megger (well known brand for insulation testers).They are much better than the cheap $20 LCR transistor testers.Only tests up to 1KHz, only 2 freq 120Hz and 1KHz.Does not do ESR directly, you need to use the D/Q and convert that to ESRDave also did a review of the BK Precision 879B, which almost looks identical.That one does have ESR built in.I actually thought that the U822c was Agilent/Keysight because the model started with 'u' but it isEucol. Never come across this brand before.Looks like the case design is identical for a number of manufacturers.I see that it supports 100, 120 Hz, 1KHz, 10 and 100KHz.It kind of sounds like the BK model rebadged but without teardown cannot be sure.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: October 05, 2020, 01:37:42 pm
content: U822 was scuttled in may 1945.https://en.wikipedia.org/wiki/German_submarine_U-822Maybe this is an acceptable source for the der ee de 5000?http://www.japaninabox.jp/shop/der-ee-de-5000-high-accuracy-handheld-lcr-meter-with-tl-21-tl-22-tl-23-iet/

author: Dlrowdna
author_rank: Contributor
timestamp: October 05, 2020, 04:31:30 pm
content: I dont like paypal and will not use this system anymore. I prefer alipay.
uA range of AN8008 not working - Page 1
Forum section: electronics / beginners

author: quaternion00
author_rank: Contributor
timestamp: November 01, 2019, 10:34:15 am
content: Hi,I tried to measure on microamp range on AN8008. My circuit is just a 5V power supply series with 1Mohm resistor. I expected that the dmm will display 5uA but the display did not change. I place the red probe to V/ohm/uA terminal. Tried placing the probe in series and parallel with the resistor but the display did not change. How can i measure uA on this dmm correctly?

author: mikerj
author_rank: Super Contributor
timestamp: November 01, 2019, 01:39:03 pm
content: There is a 200mA fuse in the meter to protect the uA input, have you checked to see if it's open?

author: rstofer
author_rank: Super Contributor
timestamp: November 01, 2019, 07:18:09 pm
content: In parallel with the resistor blew the fuse if it wasn't already.You can't use the uA range as a voltmeter measuring the supply voltage. Even if by accident.Your meter needs to be is series with the resistor such that the voltage flows in the red probe and out the black prove (if you want the sign correct).When you get to larger ranges, you need to be VERY careful when in the Amp range. Shorting a power supply will almost certainly blow a fuse but it may be much more spectacular if the voltage is very high.

author: quaternion00
author_rank: Contributor
timestamp: November 02, 2019, 01:00:21 pm
content: I checked the 200mA fuse if its open, and it is!. the uA terminal is located with the V/Hz terminal. So I assumed that measuring current in uA is the same as measuring voltage, which i know that measuring current needs the probe to be in series with load. Thanks for the help.

author: rstofer
author_rank: Super Contributor
timestamp: November 02, 2019, 02:38:15 pm
content: It's not just the socket selection, it's the range selection as well.I have often thought that using clips instead of probes could turn to disaster if you were to change the range switch while the clips are connected. My next thought it that it's just been luck that I haven't destroyed a couple of meters. In the old days, meters didn't have fuses and it was entirely possible to probe 480V on the 10A scale. I have seen the results of that: The meter was totally destroyed with pieces of plastic embedded in the technician's chest. Fortunately, no serious injuries.The fuses have made mistakes a lot less costly.

author: quaternion00
author_rank: Contributor
timestamp: November 03, 2019, 10:57:40 am
content: Glad that dmm nowadays have fuses on their current ranges.
UA741 as oscillator [HELP] - Page 1
Forum section: electronics / beginners

author: wexeteme
author_rank: Contributor
timestamp: April 22, 2015, 10:33:19 pm
content: Hello eevblog!lets jump to problem I am havingcircuit ->- so this circuit is supposed to give square signal on its output, but its not cause the 4th pin isn't on negative voltage, so how do I get it to negative when I only have 5V input and GND. Consider that I need minimum 5V to operate with that ua741.Please help me out here, and yea go easy on me.

author: Andy Watson
author_rank: Super Contributor
timestamp: April 22, 2015, 10:47:32 pm
content: Quote from: wexeteme on April 22, 2015, 10:33:19 pmYou can't . You will need a negative supply if you want the output to go negative.Quote5V is barely enough wake up a 741. I believe it needs about 1.5V "headroom" from each supply rail before it starts working. Try a more modern device - preferably one that claims to be "rail to rail".
UA7812 & TIP147 current booster - Page 1
Forum section: electronics / beginners

author: GreyArea
author_rank: Contributor
timestamp: July 17, 2018, 04:50:21 pm
content: Hi, I've been trying to create the attached circuit on my breadboard with little luck, been staring at it for literally hours - I'm sure I have it wired correctly (heard that before?) but it's not working as I expect.I have 15v input connected across 1) & 2) on the schematic, across the output 3) & 2) I'm measuring 14v, instead of the expected regulated 12v. After a few seconds the 7812 gets extremely hot, even with no load. Set at 15v, my PSU reports 250mA current draw with no load apart from the circuit drawn.I don't actually have any .33uF capacitors so I'm using .1uF across the 7812 input and outputs.What is the most likely cause for the above behaviour do you think? Thanks.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: July 17, 2018, 05:01:19 pm
content: why do you take a darlington transistor (TIP147)? The schematic says nothing about that

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 17, 2018, 05:14:35 pm
content: If you've wired it correctly, as shown, and the capacitors aren't burned out, then the regulator probably is.Tim
UART Communication between GSM and GPS - Page 1
Forum section: electronics / beginners

author: Aankur
author_rank: Newbie
timestamp: April 24, 2019, 10:01:02 am
content: UART Communication between GSM and GPSI want to establish a UART Communication between GSM and GPS.The Supply Voltage of GPS is 3.3V.The Supply Voltage of GSM is 3.8V.The measured RX/TX Voltage Levels of GPS is 2.8V and 0V (for logic High and logic Low).The measured RX/TX Voltage Levels of GSM is 1.8V and 0V (for logic High and logic Low).Since there is a difference between RX/TX logic levels of the GSM and GPS, So I amnot able to establish the UART Communication between GSM and GPS.I am using the interpreter of the telit GSM module to process the data of the GPS.I am not using any micro-controller to in between the GSM and GPS.Please suggest me a possible way to perform voltage (or Logic) level shifting.

author: MadScientist
author_rank: Frequent Contributor
timestamp: April 24, 2019, 11:13:15 pm
content: A simple transistor circuit on the relevant Tx lines will do the job
UART Test - Page 1
Forum section: electronics / beginners

author: pyromaniac4382
author_rank: Contributor
timestamp: August 19, 2014, 06:19:10 pm
content: I am currently in the process of wiring a 16550 UART to my Z80 computer. As a test I thought I would use the UART frequency (1.8432 Mhz) in one of those little four leg metal packages as both the input to the UART and the Z80. Will this have any adverse effects on my circuit, such as make it not work? I am attaching my schematic, and my code for reference. Thanks for the help!

author: Psi
author_rank: Super Contributor
timestamp: August 20, 2014, 06:32:31 am
content: i was half expecting this thread to be a test in coding a MCU UART to directly post to the forum over wifi or something.

author: deephaven
author_rank: Frequent Contributor
timestamp: August 20, 2014, 10:13:45 am
content: Shouldn't be a problem.

author: pyromaniac4382
author_rank: Contributor
timestamp: August 20, 2014, 05:06:32 pm
content: I have since gotten it to work. Bad wiring as always. Soon enough I will be posting to the forum via my Z80 computer.Thanks.
UART to I2C Bridge required - Page 1
Forum section: electronics / beginners

author: Vcky_electro
author_rank: Contributor
timestamp: August 02, 2019, 08:00:07 am
content: Hi ,Is there any UART to I2C converter bridge ?Thanks,Vicky.

author: Ice-Tea
author_rank: Super Contributor
timestamp: August 02, 2019, 08:07:03 am
content: First hit on Google:https://nl.farnell.com/nxp/sc18im700ipw-112/ic-i2c-bus-uart-interface-16tssop/dp/2101305

author: johnwa
author_rank: Frequent Contributor
timestamp: August 06, 2019, 08:31:14 am
content: Hi, not sure which direction you want to go in, but I had to do both in a recent project. The SC16IS740 will get you one way, and for the opposite function I ended up using a Bus Pirate in binary mode. (Actually, that was USB to I2C, but it has a separate USB chip, which you could remove if you really wanted to.)
UART1_Write command issue in micro c - Page 1
Forum section: electronics / beginners

author: NASK
author_rank: Contributor
timestamp: August 25, 2017, 03:39:46 am
content: I need to write variable(=a) value to UART like below using micro c. But UART1_Write(a) not showing value of variable a. how fix this issue?Int a;Void main (){UART1_Init(9600); // Initialize UART module at 9600 bpsDelay_ms(100); // Wait for UART module to stabilizeUART1_Write_Text("Start"); // show start textwhile (1) {a= 10;UART1_Write(a); }}

author: Ian.M
author_rank: Super Contributor
timestamp: August 25, 2017, 03:54:27 am
content: I *ASS*U*ME* you mean MikroElektronika mikroC. Please be specific!Code:UART1_Write(a);outputs a SINGLE character of codea. To output a number as ASCII characters you first need to convert the number to a zero terminated ASCII string in a buffer in RAM, then pass the pointer to that buffer to UART1_Write_Text(). For functions to convert a number to a string see the mikroC Conversions Library - which one to use and the size of the string you need to preallocate depends on the type of the number you are converting.

author: NASK
author_rank: Contributor
timestamp: August 28, 2017, 12:51:59 pm
content: I wrote a code without using MikroElektronika mikroC lib , this code useful for 0 to 99 usart TX#define _XTAL_FREQ 16000000#define Baud_rate 9600int a;char buf;void main() {SPBRG = ((_XTAL_FREQ/64)/Baud_rate)-1;TXSTA=0b00100010;RCSTA.F7=1;char *pyr=buf;a=56;while (1) {if(a>=10){buf=(a-a%10)/10 ;buf=a%10;while(*pyr){TXREG=(*pyr+48);Delay_ms(10);pyr++;if(buf==0){TXREG='0'; }}}else{buf=(a-a%10)/10 ;buf=a%10;while(*pyr){TXREG=(*pyr+48);Delay_ms(10);pyr++; }}}}