hybridfree/eevblog-posts huggingface dataset:
AC Power Generators VS Voltage & Equipment - Page 1
Forum section: electronics / beginners

author: mafiouso
author_rank: Newbie
timestamp: January 17, 2012, 04:06:58 pm
content: Hello all,This topic is regarding petrol generators and the power they produce to be used with computers etc.My background is in DC automotive so AC and this project is my hobby to learn something new. (i understand AC but have not put it to practice)i have a Rigol DS1052E Digital Oscilloscope, before i do anything stupid ill ask, can this be used to probe wall socket? if so can some one give me a rundown on how. thanksthe project:i want to compare the power a petrol power generator will make vs. wall sockets. then work out a way to filter/clean it to use on more sensitive devices. done on a domestic level.use:if i was to go camping or working in the field etc and needed my pc sensitive equipment and a safe way to power it with a dirty little gen.example:#use of power inverters dc\ac (via generators DC output)#use ups to filter power before pc or device#use of surge protectors in linei would like to hear the theory and advice from all you gurus out there on how you would approach it.thanks look forward to the replies.

author: tbscope
author_rank: Contributor
timestamp: January 17, 2012, 05:13:48 pm
content: The manual says:QuoteSo, no, do not use it to measure the wall socket.And certainly not a generator as there can be serious transients.

author: Mr J
author_rank: Regular Contributor
timestamp: January 18, 2012, 04:13:55 am
content: When we use generator for field day (ham radio) we use laptops with a small ups/surge and a start up procedure. My Genset run a bit hot at 130V but most laptop SMPS can go from 100 to 240V, we start the generator and run for a couple of minutes then flip the main breakers on. I've measure mine with a hand held scope and it's pretty clean (better than my wall outlets). If we accidentally run out of gas the ups kicks in during brown out then after the ups dies the laptop battery kicks in. It's kind of over kill but we run a server.I use a hand held scope to keep things isolated and easy.Be careful with regular plug in scopes measuring mains, ground is really ground (earth).

author: mafiouso
author_rank: Newbie
timestamp: January 18, 2012, 10:47:21 am
content: thanks for the replies guys, Mr J what genset specs are you running? are you worried about small surges say we are 230-240v maybe a 260-270 volt surge on start up or load changes? say some one plugs in a tv and turns it on. i guess with the scope i have i cant see the wave form, best i can do is watch with a multimeter atm.the plug in surge prot. have specs like- Max surge current: 144,000 amps- Clamping voltage: 710V- Max spike voltage: 6000Vi was wondering on the effects of the smaller spikes and unclean waves going into laptop transformers etc.thanks again
AC power socket for HP 415E - Page 1
Forum section: electronics / beginners

author: nadona
author_rank: Regular Contributor
timestamp: January 28, 2014, 05:47:16 am
content: I have a HP 415E which has a power inlet socket that looks like in this picture.Any one know the name of this type of socket and plug?Edit: Looks like "163" ? I just like to make sure before I order one.

author: Whales
author_rank: Super Contributor
timestamp: January 28, 2014, 09:37:15 am
content: It does not seem to be part of thecommon IEC series, but perusing theAC power plugs wikipedia pagesuggests it might be abrazillian socket. I'm just surmising from the pictures, however

author: nadona
author_rank: Regular Contributor
timestamp: January 28, 2014, 09:52:03 am
content: Thank you for the reply.I find this kind of socket from many of 1960's HP equipment. Old timers should knowI searched through the Internet and found out they call "163", "Oval", Belden "17280 or 17952" but both looks same.I used to solder the lines to the socket pins.

author: Whales
author_rank: Super Contributor
timestamp: January 28, 2014, 10:21:32 am
content: Quote from: nadona on January 28, 2014, 09:52:03 am+1Do you fill up the plug sockets with something non-conductive, or just leave it all exposed? I normally disconnect the socket internally and hard-wire a modern cord into units with this problem.

author: oldway
author_rank: Super Contributor
timestamp: January 28, 2014, 10:35:43 am
content: Quotehttp://www.sphere.bc.ca/test/hp1.html

author: nadona
author_rank: Regular Contributor
timestamp: January 28, 2014, 06:39:41 pm
content: Whale: Yes, I fill with "Shoe Goo" just for the sake of peaceful mind.oldway: Thank you very much!
AC power - Page 1
Forum section: electronics / beginners

author: Peabody
author_rank: Super Contributor
timestamp: July 07, 2022, 03:26:25 am
content: I have a 120 VAC coffee mug warmer that's a capacitive dropper zener circuit powering an MCU which turns a relay on and off. Even when the heating element is off, the zener circuit is always on. My Killawatt meter says it's drawing .5 watt, 5.8 VA, with a power factor of .08. What is my home's electric meter measuring as KWH that my bill is based on? Is it the watts, the volt-amps, or something different?

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: July 07, 2022, 03:52:19 am
content: Your meter indicates real energy usage by law. So KW-hrs.

author: ksat44
author_rank: Contributor
timestamp: July 07, 2022, 04:31:38 am
content: Most residential electric meters (in the US, anyway) only register real power, as Ground_Loop stated. Most energy used in the household has a decent power factor already, so utilities aren't that concerned about them (from my understanding, anyway). Larger businesses/factories, however, are often required to have meters which also record kVA and are charged extra if that amount exceeds the regular kW.

author: CaptDon
author_rank: Super Contributor
timestamp: July 08, 2022, 01:37:00 am
content: Your meter has both a voltage coil and current coils and reads the true watts consumed read as Kilowatt Hours or KWH. Factories with really bad power factors use capacitor banks which are sometimes automatically switched in or out to improve the power factor and reduce the excess current seen in inductive loads. The capacitor banks usually fail in a spectacular fashion and scare the shit out of anyone nearby!!!
AC PWM control in LTspice with 2 grounds  - Page 1
Forum section: electronics / beginners

author: reyntjensm
author_rank: Regular Contributor
timestamp: September 28, 2020, 08:51:56 pm
content: Hello everyone,I'm trying to make a AC PWM control. I've already got it working in LTspice but as soon as i start to use an optocoupler LTspice does strange things. I've been searching for the solution for several hours but i can't make it to work. It surely has to do something with the GND/COM nets but i don't know what i'm doing wrong. I hope somebody can help me further with this. Thank you all!" alt="" class="bbc_img" />
AC readings on DC supply - Page 1
Forum section: electronics / beginners

author: DudeGibbs
author_rank: Contributor
timestamp: March 24, 2015, 02:54:29 pm
content: Hello,Please see attached image. The goal of this project is to achieve roughly 64 volts or more from a 12volt battery.First start with 12volt battery powering L298 board. This is an Hbridge module that powers an arduino board also. The arduino connects pins 12 &13 to inputs 1 and 2 of the Hbridge. It is then coded to generate a pulse on each pin similar to a 60hz pulse. Here is code :Code:void loop() {digitalWrite(MOSFET1, HIGH); // MOSFET1 ondelayMicroseconds(360);delay(8); // wait for 8.3 mSdigitalWrite(MOSFET1, LOW); // MOSFET1 offdigitalWrite(MOSFET2, HIGH); // MOSFET2 ondelayMicroseconds(360);delay(8); // wait for 8.3 mSdigitalWrite(MOSFET2, LOW); // MOSFET2 off }The output of the hbridge gives steady 12vac. This is then fed to the secondary leads of a 18v transformer(110v primary/18v secondary). The output on the primary is stepped up to roughly 57v then rectified and filtered using the circuit provided in the attached image. The DC output is a steady 64.2vdc but Im concerned about the AC voltage I also measure on the output. When I switch the multimeter to AC, the voltage is doubled or more.Why am I seeing this ac voltage?Thank you for reading O0

author: bobcat
author_rank: Regular Contributor
timestamp: March 24, 2015, 03:05:49 pm
content: You are feeding the transformer with square wave pulses. This creates lots of AC harmonics to appear on the secondary. Try installing an LC lowpass PI filter between the bridge rectifier and the DC filter caps. Also- watch for transformer primary saturation due to the long duty cycle primary pulses. Fast transitions on transformers result in fast voltage spikes on the secondary instead of a smoothly changing voltage.

author: electr_peter
author_rank: Unknown
timestamp: March 24, 2015, 03:12:54 pm
content: You probably have a crap quality multimeter. Cheapest DMMs measure AC voltage in very strange fashion - diode+capacitor+scaling coefficient (DC can be interpreted as AC!!!). It works for true AC(but how do you know that in the first place?), but for anything else it is hopeless.Do this experiment - put meter in AC, put leads on 12V battery and check reading. If you see 0V, switch leads. If you see voltage, meter is a crap. In such case, try measuring your circuit voltage with switched leads, it should remove DC offset error. And buy a better DMM

author: DudeGibbs
author_rank: Contributor
timestamp: March 25, 2015, 12:32:02 am
content: QuoteThat was it. I get an AC reading on a battery with my multimeter.Thanks person.
AC rectification trouble.. voltage on open circuit - Page 1
Forum section: electronics / beginners

author: d4n13l
author_rank: Regular Contributor
timestamp: September 24, 2016, 08:44:02 pm
content: Hello,So I´m taking electronics as a hobby, so I´m pretty new to this stuff. I´m working on making my own power supply. The circuit starts with the AC rectifier part.T1 is a 24v, 5A transformer. So when the switch (S1) is closed I can measure the 24V between A and B. What I don't understand is that when it is open, I still can measure 6.5v between A and B.How could this be explained?

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: September 24, 2016, 09:01:16 pm
content: Although I'm logged into my Dropbox account I can't seem to view the image? All I get is:Error (403)It seems you don't belong here! You should probably sign in. Check out our Help Center and forums for help, or head back to home.

author: d4n13l
author_rank: Regular Contributor
timestamp: September 24, 2016, 09:16:39 pm
content: Sorry about that, the image should show now.

author: Towz
author_rank: Contributor
timestamp: September 24, 2016, 10:40:08 pm
content: My guess is capacitive coupling between primary and secondary, it should disappear after a load is connected.

author: Brumby
author_rank: Unknown
timestamp: September 24, 2016, 11:06:28 pm
content: What reading do you get if you unplug the power cord, coil it up and sit it next to your project?

author: d4n13l
author_rank: Regular Contributor
timestamp: September 24, 2016, 11:19:52 pm
content: Ok so I hadn´t notice this before. I shorted the terminals after disconnecting the circuit. I made a new reading between A and B and got 0v. The 6.5v are present in the open circuit only after I turned it on and off once. So I guess the voltage is stored in the transformer when I close the circuit. Is Capacitive couple the name for it?

author: Cerebus
author_rank: Super Contributor
timestamp: September 24, 2016, 11:20:20 pm
content: Quote from: Towz on September 24, 2016, 10:40:08 pmIndeed. It's worth mentioning that the meter the OP is using will have either 10Mohm or possibly several Gohms input impedance so although he's measuring 6.3 volts it's at a negligible current. The easy way to test this is to use his meter on a current range and measure the current being output when the switch is open - I'll bet it's bugger all.Just tried it with a loose toroidal 0-230V/0-25V transformer that was handily sitting two feet away and into a 10 meg meter it registered about 5Vrms to ground on one leg of the secondary with just one side of the primary connected to live. Same setup but current range recorded 31 uA to ground, which by my calculations is 429pF capacitive coupling and my dodgy capacitance meter (1% accurate on a good day) says 387pF - close enough for jazz.

author: d4n13l
author_rank: Regular Contributor
timestamp: September 24, 2016, 11:31:19 pm
content: Cool. Just learned a new thing. Thank you all.
AC Signal Below Ground - Page 1
Forum section: electronics / beginners

author: JLM
author_rank: Contributor
timestamp: January 02, 2014, 09:47:38 pm
content: I am familiar with the concept of an AC signal riding above a DC voltage. In such a case the DC component can be filtered out through a capacitor, or using the AC coupling mode on the scope, in which case the resulting waveform would be an AC signal centered on ground. I would have thought I would get the same result if the DC component is removed altogether. But when a sine wave generated by my signal generator is fed directly to my scope, the waveform is entirely BELOW ground, as can be seen in the picture. Can someone please tell me why that is?

author: Simon
author_rank: Unknown
timestamp: January 02, 2014, 09:50:03 pm
content: is the scope calibrated (self calibration) ? are you sure you don't have a DC offset set on the signal generator ? you can have a negative or positive bias

author: Jon86
author_rank: Frequent Contributor
timestamp: January 02, 2014, 09:51:08 pm
content: The signal coming from the function generator probably has a DC offset of just under 1v.

author: JLM
author_rank: Contributor
timestamp: January 02, 2014, 09:51:42 pm
content: yes, self-calibrated. I do not think this SG can provide a negative bias

author: Jon86
author_rank: Frequent Contributor
timestamp: January 02, 2014, 09:53:36 pm
content: If it can provide a bias, it's very likely it can also go negative.Which function gen are you using?

author: JLM
author_rank: Contributor
timestamp: January 02, 2014, 10:20:25 pm
content: Instek GFG-8020H

author: peter.mitchell
author_rank: Super Contributor
timestamp: January 02, 2014, 10:27:10 pm
content: Quote from: JLM on January 02, 2014, 10:20:25 pmCode:Features*Frequency Range : 0.2Hz ~ 2MHz*Coarse and Fine Tuning*Waveform : Sine, Triangle, Square, TTL Pulse*CMOS Output*Built-In 4 Digits Counter (INT Only)*Large 0.5" LED Display*Variable DC Offset Control*Output Overload Protection*VCF Input FunctionCode:DC Offset<-10V to >+10V (<-5V to >+5V into 50? load)

author: JLM
author_rank: Contributor
timestamp: January 02, 2014, 10:32:33 pm
content: Nice!! Mystery solved! You guys are great. Thanks
AC Signal Conditioning for a Digital Panel Meter - Page 1
Forum section: electronics / beginners

author: SG-1
author_rank: Regular Contributor
timestamp: June 16, 2011, 06:31:27 am
content: I have a Simpson 35 Falcon series voltmeter ( True RMS ) & the display is "bouncy". The least significant digit is changing so fast you cannot read it. A Fluke 27 DMM was used on the Simpson's input for comparison and it was stable or updated less frequently. The Simpson updates 3 times per second, the fluke updates 2 times per second.Question: I need to condition the input signal so the displayed result is more stable looking. Can I use a capacitor across the input for signal conditioning ?

author: vk6zgo
author_rank: Super Contributor
timestamp: June 16, 2011, 07:00:53 am
content: It would probably be interesting to look at the voltage with an Oscilloscope,as it seems to have problems.Have you checked it with a DMM on DC?Maybe it has a DC component which is upsetting your panel meter.VK6ZGO

author: SG-1
author_rank: Regular Contributor
timestamp: June 16, 2011, 05:31:15 pm
content: Thanks VK6ZGO. I will check on that. There are other panel meters on the same source with out the problem, but they are different models &/or manufactures.
AC Stepper Motor + Voltage question - Page 1
Forum section: electronics / beginners

author: Signal32
author_rank: Frequent Contributor
timestamp: August 25, 2018, 08:00:14 pm
content: Hello,New to stepper motors, was wondering aboutthis eBay stepper motor:Specs on the motor say Vmax = 100VAC.- Is there such a thing as a AC and a DC stepper motor, or are they refering to the fact that to drive the stepper motor the current flow will have to be controlled by a driver and therefore the driver will output AC ? Basically, could I drive this using aTB6600(ignoring that It won't provide the full 6A to get the full power) ?- Do I have to provide 100V to get the full power, how much power loss would there be if only providing say 12-24 V ?Thanks!
AC Stepper motor ?? - Page 1
Forum section: electronics / beginners

author: nour
author_rank: Frequent Contributor
timestamp: March 19, 2016, 10:17:29 am
content: I have found this stepper motor in TME herehttp://www.tme.eu/en/details/103h7823-1741/electric-motors/sanyo-denki/Motor: AC; stepper; 100VAC; step 1,8°; 2.7Nm; 1.34kg; 4AIn the description they say it is 100V AC !!I have searched the datasheet for the rated volt but couldn't find anyI think stepper motor works on DC volts(of course using driver to drive the coils with pulses, but still using DC volts!)so what does it mean AC in this situation?

author: danadak
author_rank: Super Contributor
timestamp: March 19, 2016, 11:20:31 am
content: Maybe they are using the term AC for the normal way of driving, whichis a PWM waveform, which is AC. Odd they did it that way.Regards, Dana.

author: nour
author_rank: Frequent Contributor
timestamp: March 19, 2016, 08:17:32 pm
content: I have found thishttp://www.tme.eu/en/Document/e402fe1be22f34378f0b60e0f1655d71/103h.pdfpage 42 graph for103H7823-17I think my motor belongs to this graphunder the graphSource voltage : AC100V?operating current : 4A/phase, 2-phase energization?full-stepJL1 = ?7.4x10-4kg?m2?40.46 oz?in2?use the rubber coupling?does it means it is using 100 ACV to drive the motor or this is just the motor driver voltage(which doesn't make much sense)
AC switch mode power supply connected to DC - Page 1
Forum section: electronics / beginners

author: edmundopt
author_rank: Regular Contributor
timestamp: January 07, 2021, 07:18:03 pm
content: Is it possible to do so ?So I am asking because my modified sinusoidal AC wave inverter has an efficiency of 89% at 400w and less then 60% at 30w, this is causing me a problem.What happens if a ~100v..240v AC switch mode power supply input is connected directly to DC voltage?- chances of DC voltage arcing in the inputs of the SMPS ?- components before the diode bridge that would be damaged with a DC voltage?- SMPS controller chip to be unstable/damaged because too low voltage in its input ?- stuff that I am not thinking about?- Without actually connecting it, is there some math to calculate its efficiency ?

author: CaptDon
author_rank: Super Contributor
timestamp: January 07, 2021, 07:27:13 pm
content: I guess it really depends on the supply. Some automatic dual voltage supplies may not like it as they normally operate in a voltage doubling mode on 120vac and non-doubling at 240 automatically detected. Some of the 120vac SMPS units simply full wave rectify the 120vac making around 140vdc and run from that, if so you could probably run one of those types direct from 140vdc either polarity sine there is a full wave bridge inside the device. You would really have to know the topology of the power supply in question.

author: David Hess
author_rank: Super Contributor
timestamp: January 08, 2021, 04:23:53 pm
content: Quote from: edmundopt on January 07, 2021, 07:18:03 pmNo.QuoteNo.QuoteWhy would the voltage be lower unless you make it so? Most power supplies are intended to operate with about 340 volts DC produced by the input rectifier and filter. Power supplies which use active power factor correction should operate correctly with DC inputs from somewhat lower than 170 (90 volts?) to 340 volts DC.If the voltage is too low, then the negative resistance input characteristic of the switching power supply will draw excessive current and damage the power supply. Good power supplies have an under-voltage lockout to prevent this.Some designs with power factor correction are just defective and will not operate on DC at all because they are expecting AC.QuoteThe change in efficiency will be negligible.
AC to DC battery charger showing AC output on oscilloscope - Page 1
Forum section: electronics / beginners

author: nh3
author_rank: Newbie
timestamp: April 10, 2020, 09:43:23 pm
content: This is probably a stupid question but I basically don't know anything about electronics. I was wondering if I could use an old Li-ion battery charger as a DC source for some hobby projects and out of curiosity I was wondering how well the charger produces the DC of the AC mains power. I hooked it up to an oscilloscope like this:and I get this kind of voltage (with 10x attenuation):Why is this? Shouldn't it be giving out DC not AC? What am I missing here? I also tried hooking it up like this:but got the same kind of sine wave as before. Also I don't understand this: shouldn't the other pole/pin be the ground to close the circuit with the device connected?However when I probe for example the DC pin on Arduino board, the oscilloscope shows just flat DC voltage. Is the sine wave produced only because of interference of the mains EMF?

author: james_s
author_rank: Super Contributor
timestamp: April 10, 2020, 09:51:55 pm
content: What is the scope ground connected to? I don't see both wires connected in either of those pictures. Without a complete circuit I'm not sure how you expect to get anything but capacitively coupled mains noise.

author: tautech
author_rank: Super Contributor
timestamp: April 10, 2020, 09:59:52 pm
content: Yep as James says you need to complete the circuit by connecting your probe reference lead to the negative.You can do this for this old Li charger as the SMPS effectively gives you isolation from mains earth however for any other circuit care must be taken where you clip your probe reference lead as IT IS at mains earth potential.Take care with where you connect it and if in doubt check between scope BNC shells and where you want to connect with your DMM. This reading need be sub 1V that will only be stray voltage otherwise you can damage your scope or the DUT.

author: rawrs
author_rank: Contributor
timestamp: April 13, 2020, 01:51:38 am
content: For what it's worth, I'd expect to see much higher ripple figures on a SMPS because they operate at many kHz, and the output stage has to filter that out. I would definitely not appreciate seeing ripple in the fractions of volts. You should be ok to ground to the negative rail, but just make sure that, first, make sure that the power supply isn't doing something dumb like passing mains through the transformer or interference suppression in any appreciable quantity, although you'd probably get an extra little kick off your voracious battery charger appetite if this was the case.Hope this helps - I'm a complete noob at this, so, what do I know, but I am interested in SMPSes, so take the above with a grain of salt.
AC to DC converter problem in negative side (toroidal transformer) - Page 1
Forum section: electronics / beginners

author: basantab
author_rank: Contributor
timestamp: May 17, 2018, 02:06:07 pm
content: UPDATE:so i now have 24 volt plus minus on both side finally after swapping different parts but i still do not know the reasons for it as all swapped parts are working correctly and i kept back all old parts which did not gave required voltage but now they do give.i had wrong formula before but this is what i am supposed to get..anyway i have equal voltage now.HiThe problem is shown in the picture but just in case , here is the problem.The output of toroidal transformer almost 15 volt 1 amp rms dual output.I want plus minus (5 and 12v)dc.After bridge rectifier the rms is around 17... (before bridge it is around 17 rms, no load condition).ripple is around 23volt.(both side plus minus)When i put 3300uf cap in positive side the ripple flatens and gives around 15 vdc.BUT!When i put electrolytic cap in negative side to smoothen out negative ripple i get -23 volt dc.(which burned my neg volt reg. 7912)Polarity of electrolytic cap was negative side to negative output and positive side to ground.Can anyone give me some hint about it ?I tried disconnecting everything and only putting cap plus bridge rectify but still it gives -23volt dc on negative side.Thankyou

author: RoGeorge
author_rank: Super Contributor
timestamp: May 17, 2018, 02:19:08 pm
content: I had a similar fail myself some time ago:https://hackaday.io/project/7590-retardo-davinci/log/24810-assumption-is-the-mother-of-all-fuckupsAre you sure your AC waveform in the secondary of the transformer is symmetric?

author: Gyro
author_rank: Super Contributor
timestamp: May 17, 2018, 02:23:36 pm
content: My question would be, why are youONLYgetting +15V on the positive side?With the 3300uF capacitor on the positive side, the unregulated voltage should rise to the peak waveform value. With a 15V (RMS) transformer this should be around 22-23V (1.414 x 15). The negative side is correct, I think you have a connection problem on the positive.Also, if you don't have a load on the regulator outputs yet and the 7912 is burning, then check its pinnout - (hint) It is not the same as the 7812.

author: basantab
author_rank: Contributor
timestamp: May 17, 2018, 04:01:39 pm
content: yes quite sure. checked it with oscillaocope.thanks

author: basantab
author_rank: Contributor
timestamp: May 17, 2018, 04:05:26 pm
content: Quote from: Gyro on May 17, 2018, 02:23:36 pmyes i now have 24 volt rectifies smooth dc voltage output after swapping bridge rectifier diode but i dnot know if thsi was the problem .. sometime i got 32 volt on negative and 24 volt dc out on positive and i still donot know the reson but for now i think 24 volt like you said is achieved .a bit of formula incorrect on my side.thanks for help
AC to DC power supply with multiple outlets? - Page 1
Forum section: electronics / beginners

author: snailFury
author_rank: Contributor
timestamp: November 02, 2014, 04:41:28 am
content: Hi All.I'm thinking about building a power supply for something I'm working on. I have been looking around online and I've find lots of basic info for AC-DC conversion for supplying one, or maybe two outputs. But what if I want to have a number of different outputs, each with different voltage and current requirements. I haven't found much that describes how this designed.This link shows how to do two:http://www.popsci.com/diy/article/2009-12/build-simple-dc-power-supplyTo add more would one simply have to increase the size of the transformer and add the necessary outputs using the correct voltage regulators per the output's requirements.If someone knows of a link where this has been described please share.thanks

author: TarHeelTom
author_rank: Newbie
timestamp: November 02, 2014, 05:21:24 am
content: I've so often needed two or three different voltages when working on projects, often just playing around with two different existing components which need different voltages.Recently bought an inexpensive 0-30 volt variable voltage variable current supply.To go along with that, I found several different (multiple voltage) supplys at MPJA, each for under $10. I'm going to stack them in a project box (with appropriate mounting of course) with perhaps 8 different banana jacks on the outside, each with a different voltage, with a separate ground for each different supply. Naturally, these days almost anything you find will have a higher current rating on +5 volts, just the way it is.I just don't always like to reinvent the wheel where there are so many different wheels out there.Tom
AC to DC using AD736JNZ - Page 1
Forum section: electronics / beginners

author: Nu7s
author_rank: Newbie
timestamp: September 07, 2015, 07:57:21 pm
content: Hello EEVblog forum,I'm a big fan of the EEVblog Youtube channel and I'm having some electronic problems, so what better place to ask?I would like to measure my home's electric power consumption and bought some SCT013 split core current clamps. They give out 0-1VAC for a specific range.DATASHEETLINK TO PRODUCTMy home automation (Loxone) has only 0-10VDC inputs and because the SCT's only provide AC I cannot connect them directly. I've been looking for a way to convert the 0-1VAC to 0-10VDC and came across some different methods:-Diode bridge rectifier: Cannot be used because the diode's require a minimum voltage wich is not provided.-Mosfet bridge rectifier: I don't have the required electronic experience, nor equipment- Phoenix Contact / Knick signal conditioner: While possible, very pricy and a bit overkill. Also, they require room in the electrical cabinet.-RS AC-P2-05 converter module: Also expensive and not common plus I cannot find a DIN-rail holder.-Using an arduino with a power offset to condition the signal.: This adds 2 additional logic computers in the circuit. I would rather connect to my home automation directly.However, I recently came across the AD736JNZ IC, wich according to the datasheet is able to convert true RMS AC to a DC signal.DATASHEETLINK TO PRODUCTIt has arrived today and I have undergone an attempt to connect it, but have failed doing so. I connected it like this:I chose a 33µF cap as the "Cf cap" and none for "Cav" as described in the datasheet:I am providing the IC with 3.3V. When I measure between pin 8 (COM) and 6 (OUTPUT) I measure 2.2V, no matter what input I supply.Am I looking at this at a far too basic approach and I am missing vital components, am I connecting it wrong, is the IC faulty or is it unusable for my application?Any help is welcome. If I need to provide more information, please let me know.Friendly greetings from Belgium!

author: Zero999
author_rank: Super Contributor
timestamp: September 07, 2015, 10:17:41 pm
content: The AD736 needs a negative supply to work properly.
AC variable bench supply , hobby + - Page 1
Forum section: electronics / beginners

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: May 16, 2014, 05:44:46 pm
content: It may , or I'm sure its been covered before , but my search methods do not work well .I have been setting up a repair bench mostly from hobbying ham radio , I have aways chased repair & building in all my hobbies .And on occasion will supplement little income with repairs , like a BBQ place and keeping there smokers going for $25-$50 a trip and foodI do have variac about 20amps and may add meters .Just recently went looking for other options , lots of what I see is plugged in AC outlets and stepped down to 5 - 10 volts but still AC .An example of the recent search was this B&K 1653 and A modelhttp://www.coleparmer.com/Product/B_K_Precision_1653A_150_Volt_2_Amp_Isolated_Variable_AC_Power_Supply/UX-20017-10?referred_id=778&mkwid=A8OVN0YS&pcrid=29828508279&gclid=CMP5g4L_sL4CFedFMgodnkEAMwI was a little surprised at the lack of options my searchs came up with .Since this is more hobby with little to no pay , cost is an issue ?

author: saturation
author_rank: Super Contributor
timestamp: May 16, 2014, 06:52:39 pm
content: For safety I'd put plug your variac into an isolation transformer then the isolation transformer into a SPD before mains to reduce the risk of higher voltage transients making it through. You could monitor your power supply with your DMM, both for current and voltage as you please. It should cost you less to put together than the B&K, which has been around for over 20 years as various models.http://www.radiomuseum.org/r/dynascan_k_variable_ac_power_supp.htmlwhich try to work and look like a popular Sencore PR57 model:http://www.teknetelectronics.com/Search.asp?p_ID=1459&pDo=DETAILYou didn't specify how accurate the voltage and frequency you need, so I presume power line regulation is adequate.

author: Wh1sper
author_rank: Regular Contributor
timestamp: May 16, 2014, 07:39:45 pm
content: I'm using ELV AC-PS 9000m or WSN 9000.It's a DIY kit out of the '93th nice gear.Hunt it @ebay while I'm not sure it was sold in US

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: May 27, 2014, 02:26:37 pm
content: I did give an example of use , circuit boards in general equipment , just reduced to lower voltage - mostly 5vac - 12vac .If I'm going to spend much $50 -100 + , then I may as well get more features , lower voltage under 5vac and less than a 1 volt ?I am setting up a repair bench , so not too fond of multiple connections being set up for each use - making simple testing a bigger job , I do check the adjustment with multi-meter .Being that I am getting into this now , I was surprised there wasn't more options , because so much stuff I've looked at was the same thing , low voltage AC just to run controls of gear .Another big driver of looking at setting up repair bench & powersupplies is ham radio , but that is almost all DC gear , to mains some of it .
AC versus DC switch current ratings - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 23, 2015, 12:34:33 pm
content: Am I correct in thinking if a switch is not used for switching a LIVE load, and only opened or closed with no load across it, the DC and AC current ratings are similar? And it only becomes an issue if the switch is opened or closed on a live load? (Zero crossing on AC extinguishes the arc more quickly?). Thanks.

author: Richard Head
author_rank: Frequent Contributor
timestamp: November 23, 2015, 12:40:55 pm
content: That is correct.

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 23, 2015, 12:56:46 pm
content: Thank you Richard, I am looking at commercially available generator / mains transfer switches rated (possibly optimistically) at 125 Amps for off load switching of two 50V at 53 Amps isolated SMPS units between series and parallel operation.I think something like this would do, used with no load across it? Or could I duplicate it with 4 ordinary DIN rail switches and a home made multi switching bar, with two of them inverted somewhat more cheaply?http://www.ebay.co.uk/itm/CHANGEOVER-SWITCH-GENERATOR-TRANSFER-125-AMP-1-SINGLE-PHASE-DIN-RAIL-COSDIN-/281692272367?hash=item41962af6ef:g:0HwAAOSw9N1Vk9GR

author: Richard Head
author_rank: Frequent Contributor
timestamp: November 24, 2015, 05:47:56 am
content: ChrisI haven't figured out exactly what you are doing but it sounds like a transfer switch between mains and a generator. If so then the switch does not have to make or break current, but it does have to have a centre off position. It looks like the switch you've selected does not have an off position. This is so that you can't rapidly switch between mains and generator. There should also be a two indicator lights showing the presence of mains voltage and generator voltage.If you are switching DC (batteries) then everything changes. Breakers have to be approved for DC at the voltage you are using and they have to be able to handle the fault current from the batteries.Dick

author: Ian.M
author_rank: Super Contributor
timestamp: November 24, 2015, 06:28:43 am
content: Comes from:https://www.eevblog.com/forum/beginners/2-pole-2-way-switch-question/
AC voltage on a DC power supply? - Page 1
Forum section: electronics / beginners

author: iamashwin99
author_rank: Newbie
timestamp: July 22, 2018, 04:35:35 pm
content: I was using my old routers power supply to light up an led strip with a simple LDR based night detector. When I was assembling the setup, I felt a strong tingling sensation when I touched the power supply. I took a multimeter and found out that it measured 10.2V in DC setting and about 15V in the AC setting. Troubled by this reading I switched to a cheap LED strip PSU and this too measured about 12VDC and about 20VAC.My question is whether this is a normal behaviour or something going wrong?Interestingly my 2n2222 based night detector worked for one day and stopped working from the next time I turned it on. Could the AC voltage destroy it? I'm thinking of adding a relay to output the power to leds rather than a direct connection from the transistor. Should I try building a low pass filter before the input to the transistor?

author: HB9EVI
author_rank: Frequent Contributor
timestamp: July 22, 2018, 05:03:59 pm
content: Without further infos to the PSU just guessing. what type of supply is it? old transformer based supplies often just had a rectifier and a cap but no voltage regulator; a smps could have an isolation problem between the primary and secondary side, some more infos would help
Accelerated capacitance circuit - Page 1
Forum section: electronics / beginners

author: Ravenghost
author_rank: Contributor
timestamp: May 17, 2016, 04:25:35 pm
content: Hi,I was analyzing thishttp://www.atmel.com/images/atmel-42183-design-a-buck-converter-with-xmega-e_ap-note_at04204.pdfapplication note and stumbled across an interesting circuit called "accelerated capacitance circuit". Has anyone got more information about such circuit and what capacitor values should i be looking for?

author: Yansi
author_rank: Super Contributor
timestamp: May 17, 2016, 04:49:08 pm
content: That term smells bullshit to me, never heard anyone calling it that way. But it is a common type of circuit.The principle is such, that as to turn off and on the transistor fast, there is a large current spike through the capacitor, that opens and most importantly closes the transistor faster, as the BE junction charge is carried away faster through the cap, not through the base resistor.For a small signal transistor, youre looking at something about tens to 100pF and for a bigger power BJT one you can use up to some hundred nF, depending on the base currents and BE charges involved.

author: Yansi
author_rank: Super Contributor
timestamp: May 17, 2016, 04:53:40 pm
content: And by the way, the circuit in the atmel appnote is stupid, the same can be done better with only two NPNs or with one NPN and one small NMOS respectively.To be more specific: Throw away both R2 and C4 and replace Q2-PNP with a single schottky diode anode to the mosfet gate, cathode to collector of Q3.Q2-NPN then works as an emitter follower forcing positive voltage on the gate; Q3 discharges the gate through the schottky, cutting also base current to he Q2-NPN emitter follower.

author: edavid
author_rank: Super Contributor
timestamp: May 17, 2016, 04:54:50 pm
content: Quote from: Ravenghost on May 17, 2016, 04:25:35 pmThat app note was obviously written by a non-native English speaker. The correct term is "speed up capacitor". The value is usually determined by experimentation.

author: Ravenghost
author_rank: Contributor
timestamp: May 17, 2016, 05:26:49 pm
content: Thanks everyone for answers helped me a lot!Quote from: Yansi on May 17, 2016, 04:53:40 pmWouldn't one need to use some kind of charge pump circuit to drive NMOS in high side configuration?
Accelerometer placement - Page 1
Forum section: electronics / beginners

author: symbianas
author_rank: Regular Contributor
timestamp: November 22, 2020, 10:11:27 pm
content: Hi, I have accelerometer ADXL345. I wonder what is correct final placement?Should Z axis always face ground? Or Y axis should face ground? Or placement does not mater if I will swap axis in code?

author: Dave
author_rank: Super Contributor
timestamp: November 23, 2020, 08:50:23 am
content: It's not important at all. You're getting acceleration data from three orthogonal axes from the sensor, how you choose to interpret them is completely up to you.Even if the sensor's tilted at a weird angle, it's simple enough to apply a rotation matrix (provided you have enough processing power or a low enough sample rate).

author: Siwastaja
author_rank: Super Contributor
timestamp: November 23, 2020, 09:06:10 am
content: It's good to keep in mind that many magnetometers and gyros have the axes specified differently, for example the z axis has lower noise or higher precision. AFAIK this isn't usually the case with accelerometers, but worth checking if all axes are specified similarly before deciding which way you use it.Other than that, it has all three axes available, so feel free to place it whatever suits you the best.

author: voltsandjolts
author_rank: Unknown
timestamp: November 23, 2020, 11:01:02 am
content: The ADXL345 has X and Y axis with similar specification but Z axis is slightly worse for noise and offset.So you might change placement based on that for your application.Also, something to watch out for is this device has an 'auto-select' feature to switch between I2C or SPI on the same pins.Be sure to read the datasheet about that (short answer: I2C probably easier).

author: symbianas
author_rank: Regular Contributor
timestamp: November 23, 2020, 01:51:08 pm
content: Wow! Thanks, for telling about 'auto-select' feature! I was wondering why I2C was not working sometimes. It seems that I must connect VCC and CS pins together for I2C mode. SDO pin seems to need to be connected to GND also for I2C mode.
Accomidating for a different size pot - Page 1
Forum section: electronics / beginners

author: Joker94
author_rank: Contributor
timestamp: January 05, 2012, 09:45:03 am
content: Hi EveryoneI am building the effects box as built on Hack a week.http://hackaweek.com/hacks/?p=423As i was not able to pickup any 5k pots from Jaycar is it possible to add a voltage divider to the output of a 10k to half the output to effectively half the output to behave like a 5k pot?(it is the pot above the signal input)I did not that in the video explanation the original schematic showed a 10k pot, I assume the 5k was used as it provided better results in controlling the 'depth' of the signal. Based on this using a 10k pot will not prove a problem.CheersJoker94

author: IanB
author_rank: Super Contributor
timestamp: January 05, 2012, 10:12:32 pm
content: You can use a 10k pot where the 5k pot is shown; it will just give reduced sensitivity on the control. If you like you could put a fixed 10k resistor between the wiper and the top of the pot in parallel with the variable resistance. That will change the range back to 5k at the cost of some linearity, but if the pot is originally a log pot it might not be too bad. You'd have to experiment and see what you find more acceptable.

author: jimmc
author_rank: Frequent Contributor
timestamp: January 05, 2012, 10:27:58 pm
content: Oops wrong pot, my bad. Thanks IanThe output of the 555 is high for 0.693(RA +RB).C and low for 0.693RB.C where RA is the pot, RB the 100 ohm and C the 100uF.Thus if you want identical results with your 10k pot (to the 5k shown) reduce the cap to 50uF (47u is close enough) and increase the 100 ohm to 200 ohm (220 will do).For more information see fig 5 of the data sheethttp://www.ti.com/lit/ds/symlink/lm555.pdfJim

author: IanB
author_rank: Super Contributor
timestamp: January 05, 2012, 10:36:33 pm
content: Quote from: jimmc on January 05, 2012, 10:27:58 pmThe existing 10k pot above the 555 timer is not the pot in question. It is the 5k pot above the input.

author: Joker94
author_rank: Contributor
timestamp: January 06, 2012, 02:20:05 am
content: Thanks IanIf there is some loss of linearity this will not prove a big issue as it is just a depth control of the tone. If however this proves to be an issue or i dont like it i can always swap it out for a 5k pot when i have one.cheersJoker94
accuracy of delay measurement on the scope - Page 1
Forum section: electronics / beginners

author: metebalci
author_rank: Frequent Contributor
timestamp: January 21, 2022, 04:32:05 pm
content: I am trying to figure out the accuracy of delay measurement between two channels (two pulses). I have MSOX 6000. On the datasheet I can only see things related to horizontal system and cursors, does it also apply to delay measurement ?From datasheet:Time base accuracy: ± 1.6 ppm + aging factor (1 year: ± 0.5 ppm, 2 years: ± 0.7 ppm, 5 years: ± 1.5 ppm, 10 years: ± 2.0 ppm)Δ time accuracy (using cursors):- Same channel: ± (time base accuracy x reading) ± (0.0016 x screen width) ± 10 ps- Channel-to-channel: ± (time base accuracy x reading) ± (0.0016 x screen width) ± 15 psSo I am looking lets say on 10ns/div to a delay of 20ns between two channels. Time base accuracy is something like ±2ppm. So is the accuracy?= ±(2ppm x 20ns?) ±(0.0016 x 200ns?) ± 15ps ?
Accuracy of TCRT5000 type infrared distance sensors? - Page 1
Forum section: electronics / beginners

author: MrTimcakes
author_rank: Newbie
timestamp: September 06, 2015, 07:49:29 pm
content: How accurate can these (espruino.com/InfraredProximity) IR proximity sensors be? My desire is to use them inside a Nerf dart clip/magazine to calculate remaining ammunition based on how full the clip is. Will these be accurate enough? Is there a better way to do this? (Keep in mind the clip must somehow electrically connect to the blaster)Nerf Clips/Magazines look like thisNote: This clip is modified with a rail to allow for non-Nerf (Stefan) darts to be used. Usual darts are longer and fill up the entire clip.

author: Chris C
author_rank: Frequent Contributor
timestamp: September 06, 2015, 08:51:28 pm
content: Datasheet lists typical operating range as 0.2-15mm.If you're planning to mount several in the side of the clip, for example to give 0/25/50/100% full readings, this sensor could work.If you're planning to mount just one in the end, it's unlikely this will be accurate enough. Something like this would be a closer fit:https://www.sparkfun.com/products/12728Those are old tech, easy to understand and use, with lots of examples. They work by using a lens to project a somewhat focused dot of light. Two light sensors behind another lens detect the light at different efficiency, depending on its angle relative to each sensor. The lesser the angle, the further away it is. By comparing the two sensors, it's able to estimate a distance, which is output via an analog signal.At the other end of the spectrum, a new and cutting edge optical time-of-flight module. It produces a quick burst of laser output, then measures the amount of time for that burst to bounce back. No trivial feat. Surprisingly inexpensive, and very accurate, but harder to use:http://www.st.com/web/en/catalog/mmc/FM132/CL2136/SC1934/PF260441?icmp=pf260441_bn_home_feb2015

author: Docholiday
author_rank: Regular Contributor
timestamp: September 07, 2015, 02:07:35 pm
content: Quote from: Chris C on September 06, 2015, 08:51:28 pmChris,The link for st.com is broken can you check and repost it.Thank you....

author: Chris C
author_rank: Frequent Contributor
timestamp: September 07, 2015, 08:51:50 pm
content: Checked and working. But here's a different link to try:http://www.st.com/web/catalog/mmc/FM132/SC1934/PF260441If that too fails, Google "VL6180X", the part # of the sensor.

author: Docholiday
author_rank: Regular Contributor
timestamp: September 07, 2015, 08:58:26 pm
content: Quote from: Chris C on September 07, 2015, 08:51:50 pmThank you, Chris that link worked.
Accuracy of the Teensy 3.1's internal ADC  - Page 1
Forum section: electronics / beginners

author: AlessandroAU
author_rank: Regular Contributor
timestamp: August 15, 2015, 05:42:01 pm
content: This video is more just for fun than anything, but check out how well you can make the ADC inside the teensy 3.1 track a voltage!.