hybridfree/eevblog-posts huggingface dataset:
AC switch on small DC load - Page 1
Forum section: electronics / projects

author: thisisliam
author_rank: Contributor
timestamp: December 11, 2018, 07:27:43 pm
content: Okay, I know the right thing to do would be to find an appropriately rated switch, but since I already own the switch that has the design I like I'd prefer to not have to go find the DC alternative...Situation: attempting to add a momentary push button to a DC circuit - 200mA, 12vdc MAX. The push button switch I have available is rated 5A 125/250VAC. Would it absolutely be the end of the world to use this switch with this circuit? Will I have arching issues? Or is the current just too low anyway for a switch of that rating?

author: jmelson
author_rank: Super Contributor
timestamp: December 11, 2018, 07:35:58 pm
content: Quote from: thisisliam on December 11, 2018, 07:27:43 pmYou are very UNLIKELY to have arcing with 12 V, assuming the load is not some kind of coil (with inductance).Assuming it is something electronic, there may be some capacitors in the load that draw a current surge when turned on.Most likely, it will work fine for years.Jon

author: David Hess
author_rank: Super Contributor
timestamp: December 12, 2018, 04:13:22 am
content: It will work fine. 12 volts and 200 milliamps is well above the point where dry circuits are a consideration.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 12, 2018, 12:49:58 pm
content: Quote from: thisisliam on December 11, 2018, 07:27:43 pmUse it, the current is so low compared to its ratings that it will virtually last for ever.Low current DC switches are not specifically designed to avoid arcing, anyway, it is only when you get switches carrying substantial currents that it becomes a design consideration.
AC to AC Converter - Page 1
Forum section: electronics / projects

author: nimit393@gmail.com
author_rank: Contributor
timestamp: November 25, 2013, 05:17:31 pm
content: i am working on a non servo single phase AC to AC converter (AC buck boost converter).All i got to know is that for this we need a IGBT switching circuit to get 0-50 VAC which can be added or subtracted (depending on phase of output of converter) from the main 230 VAC to get desired voltage.However i am not able to get this converter circuit.can anyone help me get a schematic for AC-AC buck boost or chopper circuit (without DC link in between two stage).i.e direct converters

author: penfold
author_rank: Frequent Contributor
timestamp: November 25, 2013, 06:29:29 pm
content: Some more information about the intended application would be quite useful, for example, whether or not the target efficiency is import, the kind of power level you're working with, whether noise tolerance is an issue with downstream devices etc,For a general case that scales well in power and good efficiency, bucking circuits would be pretty easily implemented with a single phase matrix converter, boosting is slightly more difficult and would most easily be achieved with an intermediate DC bus,There's always the nice clean low noise option with digital control... a motorised variac
AC to DC converter - Page 1
Forum section: electronics / projects

author: alamwte
author_rank: Regular Contributor
timestamp: May 01, 2021, 06:37:28 am
content: Hi,I am going to design an AC to DC power converter. I need the output voltage of 48v and output current of 12A.I have found an IC datasheet that its typical application is designed for 20v and 2A.Can I use this IC for my application? In a Excel file you can define the output voltage and power and then that change the capacitors and resistors.But when I put 2000v output it don't recognize error!!I will attach datasheet and Excel file below

author: mariush
author_rank: Super Contributor
timestamp: May 01, 2021, 06:41:34 am
content: 48v is standard voltage, there's mass produced power supplies out there, most likely cheaper than what you could possibly do.And no look at other chips.

author: alamwte
author_rank: Regular Contributor
timestamp: May 01, 2021, 06:47:12 am
content: Thank you,
AC to DC voltage mirror for reference? - Page 1
Forum section: electronics / projects

author: pacmann
author_rank: Contributor
timestamp: August 06, 2021, 07:32:28 am
content: Whats the best way to convert an AC voltage to its equivalent DC for measurement? The output can be low current in the 10-50 mA range.As an example, if there is 200 vpp AC I want to create a 200 vdc reference voltage. Does this kind of circuit have a name?

author: pacmann
author_rank: Contributor
timestamp: August 06, 2021, 09:22:37 am
content: Can the circuit be as easy as a bridge rectifier with parallel capacitor?

author: Zero999
author_rank: Super Contributor
timestamp: August 06, 2021, 09:59:57 am
content: It depends on whether the voltage drop across the rectifier diodes is a problem or not. Under light loads, a silicon diode will typically drop around 0.6V and they're two in series in a bridge rectifier giving a total drop of 1.2V.Another thing to note is AC voltages are normally specified by the RMS (Root Mean Square) voltage. A rectifier and filtering capacitor will give you the peak voltage, which is higher by a factor of √2, so 200VAC RMS in, will give 200√2 = 283VDC out, minus the diode voltage drops.

author: pacmann
author_rank: Contributor
timestamp: August 06, 2021, 10:45:38 am
content: Quote from: Zero999 on August 06, 2021, 09:59:57 amThanks for explaining. I think the drop of 1.2v will be ok.Can the RMS be compensated with someting like a resistor divider at the DC side? Is there a better way than a divider?Is there a way to isolate the input without using a transformer because of the low output current requirement?

author: Zero999
author_rank: Super Contributor
timestamp: August 06, 2021, 11:14:27 am
content: Quote from: pacmann on August 06, 2021, 10:45:38 amIf the AC signal is always a sine wave, then a potential divider can be used to divide by √2.An analogue isolator can be used to isolate the signal, but the usual way is to digitise the signal first and pass it through a digital isolator. It's also possible to use PWM, or PFM the signal before passing it through a digital isolator.

author: fcb
author_rank: Super Contributor
timestamp: August 06, 2021, 11:20:32 am
content: What level of accuracy? Peak AC or RMS?

author: wraper
author_rank: Unknown
timestamp: August 06, 2021, 11:27:30 am
content: For measurement you don't normally outright rectify high voltage and smooth it. It should be a voltage divider followed by precision rectifier. You will need to add true RMS to DC converter if you want to measure RMS voltage for different waveforms.https://circuitdigest.com/electronic-circuits/half-wave-and-full-wave-precision-rectifier-circuit-using-op-amp
AC voltage / ATM90E26 reference circuit confusion - Page 1
Forum section: electronics / projects

author: cmorgan
author_rank: Newbie
timestamp: November 24, 2018, 02:18:20 pm
content: I am trying to design a circuit to measure power consumption with the help of ATM90E26 Application notehttp://ww1.microchip.com/downloads/en/AppNotes/Atmel-46102-SE-M90E26-ApplicationNote.pdfLooking at page 4 it looks like they are considering the L line to be the ground for this section of the circuit. They also have a comment in the introduction where they say "Considering low-cost and anti-tampering etc., ground of the single-phase energy metering IC is generally connected to the phase line (L line) of the single phase power supply."I'm aware of the issues of connecting directly to mains like this and plan to use an isolation IC to separate this portion from the rest of the circuit.Is it typical to use one of the hot legs, the L line, as a circuit ground? Why not the other way around?What if I'm using two hot legs of 240VAC and no neutral? Can I just hook them up interchangeably using one of the legs as the circuit ground?I've done mostly digital electronics and I'm having trouble conceptualizing what occurs if the circuit ground is an AC signal like in this circuit. Doesn't the potential across the capacitors change as the AC voltage changes in that case? Or are the grounds indicated on the page 4 schematic not all the same voltage reference even though they are the same symbol?Chris
AC - Page 1
Forum section: electronics / projects

author: Jacktron
author_rank: Contributor
timestamp: September 06, 2024, 11:51:29 pm
content: I am trying to create a circuit that can generates AC magnetic fields in two pairs of helmholtz coils. How can I best do this and could you include schematics from a place like falstad?

author: IanB
author_rank: Super Contributor
timestamp: September 06, 2024, 11:54:43 pm
content: You get a 120 V AC solenoid and connect it to the mains. Job done.If that's not the answer you want, you might need to give just a tiny bit more information?

author: Jacktron
author_rank: Contributor
timestamp: September 07, 2024, 12:03:16 am
content: I added a little more info: I have two pairs of helmholtz coils that I want to generate ac magnetic fields of for example 0.01 T

author: PGPG
author_rank: Frequent Contributor
timestamp: September 07, 2024, 12:42:28 am
content: Quote from: Jacktron on September 07, 2024, 12:03:16 amWithout knowing anything about these 4 coils (I understand two pairs as four) the only what can be said is to supply them with adequate current.You can use AC mains as source and trafo (auto-trafo) or resistor to reduce the voltage/current applied to them.

author: Smokey
author_rank: Super Contributor
timestamp: September 07, 2024, 12:47:26 am
content: ... DC ....Your move..

author: Jacktron
author_rank: Contributor
timestamp: September 07, 2024, 12:48:40 am
content: one pair with a radius of 2 cm and another with 1 cm

author: Jacktron
author_rank: Contributor
timestamp: September 07, 2024, 12:49:32 am
content: I am trying to create an ac field

author: Andy Chee
author_rank: Super Contributor
timestamp: September 07, 2024, 01:03:26 am
content: what AC frequency?what inductance coils?what thickness copper wire?

author: Jacktron
author_rank: Contributor
timestamp: September 07, 2024, 01:08:27 am
content: 10 hertz20 coils.1 cm wire

author: Andy Chee
author_rank: Super Contributor
timestamp: September 07, 2024, 01:31:47 am
content: what is your input voltage? is it a battery? what kind of battery? or is it mains powered?Can you give a wider picture of your project? Is this a hydrogen generator?

author: Jacktron
author_rank: Contributor
timestamp: September 07, 2024, 01:39:21 am
content: i have 9v dc battery
AC1627 based bluetooth audio module config/serial interface - Page 1
Forum section: electronics / projects

author: komradebob
author_rank: Contributor
timestamp: October 07, 2017, 04:09:58 am
content: So I had a need to move audio across the room and bought a bunch of little BT modules based on the JieLi AC1627 chip. Apparently quite a capable little device which also supports USB, FM radio and serial data. The module is designed for running a set of headphones or the like from your mobile phone, comes complete with V+/V-, Next, Previous, Reject Call, Answer Call, Call Last #, functional on 4 buttons, speaker output, mic input, headphone jack 3 pins marked TX/RX/Gnd and three marked G/M/C.Only one problem. When you power it up, it tells you it is connected/not connected. In Chinese. I'd really like to either turn this off or change the language.Of course there is no manual for the module. Even so, not a bad deal for $6US.Sold here:http://www.icstation.com/bluetooth-stereo-audio-receiver-module-earphone-loudspeaker-module-output-with-50hz-18khz-p-12053.htmlHooking up the serial port (115k baud) reveals debugging output, but no apparent input that has any effect. Output looks like:task_list_cnt=0x04444SYS_EVENT_DEL_TASKdel lmp okdel stack okdel_ket_masg*****Next_Task_Name2:BtStackTaskMSG_BT_STACK_STATUS_CHANGEMSG_BT_STACK_STATUS_CHANGEplay_toneremote name : <redacted>del music dec phy succdel_music_task: succ--------tone_mutex_stop------------------Pushing buttons results in:MSG_BT_PREV_FILEMSG_BT_NEXT_FILEMSG_BT_PPMSG_BT_ANSWER_CALLMSG_BT_CALL_REJECTAnyone seen this IC/module before? Got any clue as to what the other port is? Data sheet maybe?Thanks!Bob
Accelerated stress test for old electrolytic capacitors - Page 1
Forum section: electronics / projects

author: conductivity
author_rank: Contributor
timestamp: June 27, 2022, 02:02:43 pm
content: "The most commonly accepted method is based on the thermal stress over the rated temperature of the capacitors, which is based on the application of the Arrhenius’ law to the chemical reaction speed (10)."https://epci.eu/aluminium-electrolytic-capacitors-accelerated-lifetime-modeling/Good overview of accelerated stress testing of electrolytic capacitors in the link. Have you tried to use extra heat for measuring old electrolytic capacitors with an LCR meter? New ones are made to handle their rated temperature for many hours without drifting out of spec.Yet, do you think it would be a good idea to use a hairdryer and thermometer or something like that when measuring old electrolytic capacitors? In other words, do you think it is likely to reveal significant data compared to ambient/room temperature? I am only thinking about hobbyists like me knowledgeable that companies specifically don't like to waste time/resources.

author: TheMG
author_rank: Frequent Contributor
timestamp: June 27, 2022, 03:06:16 pm
content: Bad idea, short term heating won't do much. Capacitors should be measured at room temperature. ESR tends to actually decrease and capacitance increase with higher temperatures, so a cap that is actually out of spec could appear good when heated up.This is also part of the reason sometimes a device will work fine as long as it remains on, but if turned off long enough to allow it to cool to room temp and then powered back on suddenly it fails.

author: Siwastaja
author_rank: Super Contributor
timestamp: June 27, 2022, 05:00:35 pm
content: Indeed, understand the fundamental difference, almost orthogonality ofcausingaging, ormeasuringaging.High temperature is used to make capacitors age faster, but the effects of increased ESR is best seen at low temperatures.

author: jwet
author_rank: Frequent Contributor
timestamp: June 27, 2022, 05:28:57 pm
content: As the last poster said, ESR actually improves with temperature. One of the electronics repair you tubers I've seen looks (Mr. Carlson?) probe around caps with a soldering iron and see if the unit starts working magically with he heats them up- kind of the opposite of freeze spray.
Accelerometer pricing. - Page 1
Forum section: electronics / projects

author: phil from seattle
author_rank: Super Contributor
timestamp: December 23, 2017, 06:49:22 pm
content: This is half rant, half question. I've been researching/experimenting with accelerometers to add to various projects I want to do and found some very strange pricing on some of them.Basically, you can buy a small board with an accelerometer and a few other parts for not much more than the cost of the bare IC. This isn't just a china thing either. An example: Sparkfun sells an H3LIS331DL breakout board for $9.95 (https://www.sparkfun.com/products/14480). The cost from all the major Distis in the thousands quantities is around $6. A number of others are like that, too. Clearly SFE is getting much, much better pricing than that, I'd guess less than a dollar. That's not the only one. Yet other manufacturers's accelerometers with similar capabilities go for $1 Q1 from the same distis. Doesn't make sense to me. Are the makers going the route of pharmaceutical pricing? (list super high, negotiate everything)Fortunately, there are plenty of choices at the $1 Q1 price point. The Kionix KX122-1037 cost me $0.89 each Q10. It has a bit of an offset that's easy to compensate for but otherwise it's a perfectly fine chip.And, of course, all the accs appear to be going to a 2x2 LGA package with 12 or 16 .25 mm x .275 mm pads. The chip is about one quarter the size of a grain of rice. But then, what would life be with out challenges?

author: Jeroen3
author_rank: Super Contributor
timestamp: December 23, 2017, 07:14:42 pm
content: Maybe sparkfun gets them a bit better, say 4-5$, that still leaves 5$ for board, assembly testing and packaging.I’m not a pricing expert, but for a board where you can putmanyon a frame, I’d think it could work.

author: phil from seattle
author_rank: Super Contributor
timestamp: December 23, 2017, 07:28:17 pm
content: If they have $5 in parts costs alone, they are losing money. Plus, they have similar pricing on breakouts where the parts do cost <$1 in 1000s quantity.

author: texaspyro
author_rank: Super Contributor
timestamp: December 23, 2017, 08:02:58 pm
content: I bought some 10 axis IMU boards off Ebay for $12 each. The MS barometer chip alone sells for $36 on DigiKey.

author: phil from seattle
author_rank: Super Contributor
timestamp: December 23, 2017, 08:31:58 pm
content: For a while now, I've suspected there is some sort of "Chinese discount" going on. Even the 1000s disti pricing is still more than the cost of buying a board like that off ebay/aliX/... I know the Chinese take slim margins but they aren't going to sell it for more than it costs to make it.

author: bson
author_rank: Unknown
timestamp: December 26, 2017, 01:45:16 am
content: Quote from: phil from seattle on December 23, 2017, 06:49:22 pm$6 for what - the chip or the board?Mouser sells thechipfor $1.24 in 1000s. $1.07 if you get two full reels of 4000 each. $2.51 for a single.https://www.mouser.com/productdetail/stmicroelectronics/lis331dlhtr?qs=sGAEpiMZZMvAvBNgSS9LqglfYWqF%2Fb%2Fr
Accelerometer to WASD - Page 1
Forum section: electronics / projects

author: moonquasar
author_rank: Contributor
timestamp: August 14, 2016, 04:17:50 am
content: Here is a small program I made to play my favorite Quake3 Arena mod -- Urban Terror.This is not my original idea. I saw someone else do it on youtube.The dev board is kl46z. It has an accelerometer already on it. The board is placed on a wobble board to act as a foot driven joystick. Urban Terror has no analog support, therefore movement must be sent as key presses. The hardware button levels the device so that it can be operated at an angle.It works pretty well. Would be nice to have a return spring so that the board settles to zero when I take my feet off.You can see in the code, I tried to reference the Z axis for twisting the board. It took me a lot of noodling before I discovered that the axis which is aligned with gravity is blind to rotation. There is likely a way to use the magnetometer in a sensor fusion arrangement but I have not gotten that far.http://pastebin.com/9ec1e6C1Constructive criticism welcome.
Accelerometers/Inclinometers in Metal enclosures - Do they work? - Page 1
Forum section: electronics / projects

author: NW27
author_rank: Regular Contributor
timestamp: July 16, 2018, 11:09:40 pm
content: Hi,I'm designing a PCB to go in an enclosure with a metal cover. This will then be mounted inside the engine bay of a vehicle.Will the metal act as a shield and stop the sensor from working?Example sensor is the ADXL345http://www.analog.com/en/products/sensors-mems/accelerometers/adxl345.html.I don't see anything in the datasheet about shielding affecting the device.Thanks,Neil.

author: jpanhalt
author_rank: Super Contributor
timestamp: July 16, 2018, 11:48:09 pm
content: They work in metal enclosures. In fact, the accelerometer I use comes in a sealed metal enclosure instead of epoxy.

author: james_s
author_rank: Super Contributor
timestamp: July 17, 2018, 02:54:03 am
content: If you can find a material that blocks gravity then you'd be able to violate the laws of the universe. Sure would be handy stuff.
acceptable Q factor for capactior? - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: February 28, 2014, 09:15:25 pm
content: What is an acceptable Q factor for a 12000uF 400VDC capacitor?Is a D of 0.05/Q=20 acceptable? I can't find the datasheet for what I am using, so I was wondering about a rule of thumb for capacitors this size.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 28, 2014, 09:20:11 pm
content: Aluminum electrolytics typically place 0.3-0.05, more or less one-to-one with voltage, with better figures at higher voltages.If you don't have a datasheet, worst-case is probably best to guess... if your application can tolerate 0.1-0.2, you're probably fine.Tim
Access an OM5640 Camera Chip via USB? - Page 1
Forum section: electronics / projects

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 10, 2020, 12:54:38 pm
content: HiI ask before but I dont get any usefull replays to.I hope that is the right area to ask.I got this Camera Module a long Time ago:https://www.delock.de/produkt/96371/pdf.html?sprache=enThe sayed it have, use a "• Standard SCCB interface (I²C Bus)" not how to access that?!I need to change the resolution to QSXGA (2592 x 1944) for the best Images possible.Disable the " - Automatic white balance (AWB)" and so on.The Manual also say the use a Serial Interface but now how to access that?!I download the Manual from OV. The are very good!At first i would like active the Test Pattern to see I can change settings:Code:0x503D PRE ISP TESTSETTING 1 0x00 RWBit: Color bar enable0: Test disable1: Color bar enableBit[3:2]: Color bar style00: Standard eight color bar01: Gradual change at verticalmode 110: Gradual change at horizontal11: Gradual change at verticalmode 2But how the get the Code into the damn Module?!Thanks!

author: wraper
author_rank: Unknown
timestamp: April 10, 2020, 01:10:21 pm
content: You cannot work with camera module directly so it's datasheet has no use for you. You should select camera settings just like with any other webcam. Normally you change settings from application which uses webcam, at least on windows.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 10, 2020, 02:34:04 pm
content: How to communicate with eh Standard SCCB interface (I²C Bus)?

author: wraper
author_rank: Unknown
timestamp: April 10, 2020, 02:56:37 pm
content: Quote from: Lord of nothing on April 10, 2020, 02:34:04 pmYou can communicate to it as much as you want but camera won't work as you want just because of that. You ask as if there isn't any controller chip (SM3732) which transfers data via USB.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 10, 2020, 03:49:25 pm
content: Sure the use that Chipset. How can I set the Settings?I havent any Software for the Camera.How can I set the settings in the Camera not in the Client like VLC?

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 22, 2020, 09:45:36 am
content: Does anyone know?

author: amyk
author_rank: Super Contributor
timestamp: April 23, 2020, 03:56:20 am
content: You'll need to figure out if there are some vendor-specific commands that will let you configure the sensor. There may be, but you'll need to do some reverse-engineering.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 23, 2020, 01:58:26 pm
content: Well the German - Chineese Company tell me just what is written in there Datasheeds.I guess the use some default thinks. Is there a Software who can communicate with both Chipsets?
Access TTL without TTL-USB cable? - Page 1
Forum section: electronics / projects

author: sam1275
author_rank: Frequent Contributor
timestamp: January 21, 2017, 10:17:54 am
content: Hello.I'm trying to hack a router with a 4 pin TTL header, first I use a USB to 9 pin RS232 cable, but it only get garbage data, after lots of trying then I saw on the internet that RS232 have a much higher and inverted signal level than TTL... I'm glad I didn't destroy itI don't have a USB-TTL cable, but I have a beaglebone black, is it possible to use it as a USB-TTL converter?Thanks.

author: Ian.M
author_rank: Super Contributor
timestamp: January 21, 2017, 10:57:24 am
content: 50/50 odds you've blown the router MCU's RXD input. A USB<=>Logic level serial interface or a RS232 level<=>Logic level converter *MUST* match the Vdd_I/O supply voltage of the MCU or UART it is to be used with, with the rare exception of 3.3V logic level intefaces with 5V tolerant inputs. The *ONLY* thing that may have saved your bacon is the limited current available from a standards compliant RS232 line + the MCU's internal protection diodes.Foe %DEITY%'s sake, get the right part for the job - either a USB<=>Logic level serial cable or module that outputs the correct logic high level or takes its Vdd_I/O from the target to set the level, or if you want to use your existing serial cable, a proper level converter. (e.g a MAX3232 built up in a circuit according to its datasheet)If you really know what you are doing, and the Vdd_I/O levels match, you cold use one of the Beaglebone Black's UARTs from a terminal program running on the black. However if you get it hooked up wrong or the levels don't match, you could easily end p with both a damaged router and a damaged black. 330R resistors in series with both data lines would reduce the risk, but personally, I'd rather use a cheaper option in case I FUBAR it.

author: sam1275
author_rank: Frequent Contributor
timestamp: January 21, 2017, 03:15:21 pm
content: Thank you very much!
accounting for burden voltage in my multimeter - Page 1
Forum section: electronics / projects

author: jwm
author_rank: Regular Contributor
timestamp: November 15, 2013, 05:00:46 am
content: I'd like to do some low voltage small current measurements, Although I'd eventually like to spring for a uCurrent, I was wondering whether I could do something simpler and cheaper and junk-partable in the interim, namely put an op amp in the loop in a linear regulator configuration taking its negative feedback from after the multimeter to keep the actual voltage presented to the device at the reference level. Something like the attached schematic.I am not driving crazy loads, I am testing avr uCs and msp430's current usage under different conditions/voltages and want to verify some of the crazy awesome current consumption claims made by the msp430fr family. The meter I am using is a 5.5 digit HP 3478A which is known to have a particularly bad burden voltage.Again, I don't need uCurrent accuracy (yet), but I'd like something to at least improve things down at the 1.8-3.6V range. circuit improvement ideas are welcome. Something I was thinking of was ditching the 2n2222 and just using the op amp output directly, I don't have any immediate plans to test over the 40mA or so range (cpus driving LCDs and maybe an LED) so can probably find an op amp that can source that in my junk bin.

author: IanB
author_rank: Super Contributor
timestamp: November 15, 2013, 05:08:14 am
content: If the device current is really low (uA?) then I can't see burden voltage being a problem. Passing a few uA through a 100 ohm meter impedance is only going to drop a few mV. The DUT would hardly notice it.But assuming the problem is worse than that, do you have an adjustable bench power supply? All you have to do is to put a voltmeter across the load, then wind up the power supply voltage until the load sees the appropriate voltage at its input terminals.

author: jwm
author_rank: Regular Contributor
timestamp: November 15, 2013, 05:22:08 am
content: Quote from: IanB on November 15, 2013, 05:08:14 amYeah, the power supply trick is what I was going to try but I figured it would be nice to have something that "just works" so I can dial up and down the voltage on my reference or fiddle with uploading new firmware without the extra step.Ah true, yeah when running solely at those low currents it isn't much of a burden. I guess until the current reaches the mid tens of mA range then it isn't going to affect things much. I do plan on doing things like testing PWMing LEDs, which may get up to that range. Conceptually would my circuit help though were I measuring higher current low voltage things?

author: dannyf
author_rank: Super Contributor
timestamp: November 15, 2013, 11:44:19 am
content: QuoteWhat "burden voltage" at that kind of current levels?QuoteYes: stick your meter in there and be done with it.
Accubeat AR-60A Rubidium Frequency Standard - Page 1
Forum section: electronics / projects

author: erikka
author_rank: Regular Contributor
timestamp: August 13, 2021, 02:23:13 pm
content: Anyone any experience with these? Can't find any info, except a spec sheet from Accubeat itself.

author: Renate
author_rank: Super Contributor
timestamp: August 13, 2021, 06:05:07 pm
content: Could you qualifiy your interest in this, please?Intended purchase? Repair? Idle interest?(No, I don't know anything, just trying to be helpful.)

author: thinkfat
author_rank: Unknown
timestamp: August 13, 2021, 06:11:20 pm
content: Other than that I was tempted by those when I found them being sold on ebay a while ago I have no actual data either. But I'm interested on what people know about them so I'm bumping the thread.

author: erikka
author_rank: Regular Contributor
timestamp: August 15, 2021, 12:51:39 pm
content: According to the spec sheet those with the TAD option will allow voltage fine control of the frequency (+/- 1.5e-9) so they seem to be usable in a GPSDOSpec can be found here:http://www.tect-electronics.com/uploads/files/Accubeat/AR60A%20Spec%2024%205%2011.pdfBut given the limited reactions they do not seem to be very popular.
Accuracy of Bluetooth xtal frequency - Page 1
Forum section: electronics / projects

author: Renate
author_rank: Super Contributor
timestamp: October 31, 2021, 05:03:11 pm
content: This is both a general question and a specific question.Have you ever checked, trimmed or had problems with the accuracy of Bluetooth xtal frequency (on anything)?I've been playing with Cypress CYBLE-012011-00 modules. It has selectable capacitor trim for the input and output of the xtal. The (completely wrong) default values are 8.2 pF & 14.3 pF. I just measured that as being sharp about 100 ppm. In the fine print Cypress tells you to use 17.8 pF for both values. I measure that as being sharp about 20 ppm. For 0-ish ppm I see 20.7 pf for both values. That seems like a heck of a lot of capacitance to me.How am I measuring? I'm using a PPS out of a GPS to hit a capture on a timer being fed with the 24 MHz on the module. Ok, there is some bobble but the result is pretty consistent. The GPS has been running for hours and has 9 captured satellites and a HDOP of 1.2So, the 100 ppm was a complete disaster. It took 20 tries to pair and the connection dropped all the time. The 20 ppm works fine but I wonder if 0 ppm would be better. Cypress seems to say that unit to unit variance isn't big enough to justify unit tuning.
Accuracy of Current Source for Micro-Ohmmeter  - Page 1
Forum section: electronics / projects

author: namster
author_rank: Regular Contributor
timestamp: December 22, 2018, 10:26:27 pm
content: Hello ,for my final years projet i have to release a Micro-Ohmmeter with 4 Wires methods , i start with uncertainty Calculation , According to the calculations in 20m \$\Omega\$ Range and resolution of 1µ \$\Omega\$ , the relative Error in Current have to be 0.01mA for 1A ,Are my calculations correct ?Vref ( 10Volt )

author: kony
author_rank: Regular Contributor
timestamp: December 23, 2018, 11:05:03 pm
content: Direct measurement is quite poor choice both precision and SNR wise. This is usually done with AC excitation and synchronnous demodulator.

author: 001
author_rank: Super Contributor
timestamp: December 30, 2018, 08:23:48 am
content: Quote from: kony on December 23, 2018, 11:05:03 pmDo You mean bridge measurments?

author: kony
author_rank: Regular Contributor
timestamp: December 30, 2018, 08:28:52 am
content: Bridge measurement is orthogonal to that, but also helps.
Accurate frequency measurements without a frequency counter  - Page 1
Forum section: electronics / projects

author: MrSlack
author_rank: Frequent Contributor
timestamp: May 02, 2016, 08:19:08 pm
content: My circa 1975 frequency counter just blew up leaving me a smoking unobtainium IC and no frequency measurement ability. Boo hiss. I've drafted up a schematic for a new one, fullt discrete based on 74hc390+4511+other bits I floating around. Unfortunately I've got to wait 3-5 days for the bits to arrive and then a couple of evenings to throw it together.After some reflection, this made me think about the times before ubiquitous digital logic and precise crystals. This begs the question: how did people accurately measure frequency back then?

author: dannyf
author_rank: Super Contributor
timestamp: May 02, 2016, 08:35:09 pm
content: A charge-pump would do. Basically, if you add the same amount of charges to a charge-storage device (a capacitor for example), you get high voltage across it when the charge frequency is controlled by your input signal.A small RC circuit, a capacitor + a gate would do.

author: DimitriP
author_rank: Super Contributor
timestamp: May 02, 2016, 08:55:44 pm
content: Before "frequency counters" , there was this:https://en.wikipedia.org/wiki/Absorption_wavemeter

author: AF6LJ
author_rank: Unknown
timestamp: May 02, 2016, 09:03:49 pm
content: https://www.google.com/?gws_rd=ssl#q=heterodyne%20frequency%20meterThese were the Go-To frequency meters of the 20s-60s.

author: MrSlack
author_rank: Frequent Contributor
timestamp: May 02, 2016, 09:58:46 pm
content: Thank you very much everyone. Lots of interesting reading ahead!

author: IconicPCB
author_rank: Super Contributor
timestamp: May 02, 2016, 10:23:32 pm
content: Look for transfer oscillator approach..probably similar to heterodyne approachUse a comb generator and a mixer.. look for adjacent comb lines make at whihc a beat tone is observed and solve for frequency of incoming signal

author: barry14
author_rank: Regular Contributor
timestamp: May 02, 2016, 11:57:36 pm
content: There were also analog frequency meters such as the General Radio 1142 which not only measured frequency but acted as a frequency discriminator (FM detector). It operated by generated a fixed amplitude, fixed duration pulse for each zero crossing of the input signal. Then these pulses were averaged and the result fed to an analog voltmeter. Hewlett-Packard also made a similar unit.
Accurate Thyristor control, phase or cycle control - Page 1
Forum section: electronics / projects

author: AlfBaz
author_rank: Super Contributor
timestamp: November 30, 2012, 12:44:51 am
content: Hi allI want to build my own heater controller for a toaster oven using a triac or scr's.It will be micro controlled as I want to implement the full reflow cycle of temperature ramp up, saturation, reflow, cool down.I don't know the proper terminology for the two output methods I have so a quick description insteadThe first is controlling the angle at which the thyristor fires, essentially chopping up the sine waveSecond is zero crossing activation for multiple cycles.I can see two ways to control output in this second method. Choose a time period of say, several seconds and vary the on/off duty cycle (pseudo PWM) or simply just turn the heater elements on/off according to PID algorithm output.I understand that changing methods is merely a change in software, but was curious if anybody had experience in which method (or others not described here) is the most accurate.The other question I had is whether or not to employ burst triggering in the phase angle method.I have used this successfully before in a design using 4 quadrant SCR's with RC snubbers driving an inductive load where current control was critical.With the advent of high commutation, 3 quadrant SCR's and triacs and that a stray cycle here and there in a lagging system such as this, coupled with the fact that most heater elements would be mostly resistive, would it be over kill or should I consider CCT design re-use?

author: AlfBaz
author_rank: Super Contributor
timestamp: December 01, 2012, 12:48:04 am
content: I've had a little think about it and the more I do the answere seems obviousThe smaller the output steps the finer the control duh!

author: Bloch
author_rank: Unknown
timestamp: December 02, 2012, 12:10:53 pm
content: Quote from: AlfBaz on December 01, 2012, 12:48:04 amWell to a point. How slow/big mass are going to "controlled" ?One extreme example 1 watt heater in a living room. It will be very hard to measure room temperature differences if it is on 100% or 1%My guess is 10mS/8,33mS (one half sinus wave) will be just fine.
AC/DC 500W Supply EMC Issue's - Page 1
Forum section: electronics / projects

author: fordj06
author_rank: Newbie
timestamp: February 07, 2020, 10:25:07 am
content: Hi guysI'm a EE student on placement and I've just taken over an existing power supply design that was never EMC tested. We are now wanting to put the design into a system that needs to be certified for EMC class A (EN 55032 CISPR 32). I took the system to the EMC test house the other day for some pre-compliance testing and it failed, miserably.We determined that it was the AC/DC power supply that was the source because the system was still failing with just the power supply in the test rack.We are using a PFE500SA-48 from TDK-Lambda as the main power module and have used the same supporting passives as they used for there in house verification. (See attached schematic).Some notes from the pre-compliance:- It failed both emission and immunity- When we increased the size of the earthed chassis the results were worse- It was failing at around 30MHz (Ive attached some results)- It was broadband interferenceAny experience would be appreciated.Thanks

author: moffy
author_rank: Super Contributor
timestamp: February 07, 2020, 11:51:54 am
content: Have you tried a suitable ferrite in series with the mains cable to attenuate the 30MHz etc?

author: poorchava
author_rank: Super Contributor
timestamp: February 07, 2020, 02:25:26 pm
content: Am I missing something or you don't ahve a capacitor between primary and secondary ground? Ie a way for interferences to close the loop. you could try adding a small (eg 4.7n y1 type) capacitor between grounds.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 07, 2020, 02:39:04 pm
content: Probably do this.L1 probably isn't doing much.What's conducted look like?Tim
AC/DC calculations for transformer - Page 1
Forum section: electronics / projects

author: diod
author_rank: Newbie
timestamp: November 08, 2015, 06:51:46 pm
content: Hello,I am having a hard time finding right formulas for calculations of AC/DC one phase transformer, using RC filter and rectifiers, can anyone help please?==============================U (secondary)= +40 VI (sec) = 8 AR = U (sec) / (I (sec) = 5 OhmsP (sec) = 320 wattsU (primary) = 230 Va (max) = 0.05 (U electrical voltage instability)f = 50 HzK (pulsations) = 0.12 (the output voltage ripple)I would like to have a full wave rectifier with four diodes.===========================================How do I find transformer impedance and diode bridge resistance?How do I find primary and secondary windings and choose a right transformer type?
AC/DC Current shunt 0-30A with 250V common mode - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: January 20, 2021, 06:13:43 pm
content: Looking to improve a current measurement circuit that uses a LEM LTS 25-NP hall effect sensor. The dc offset of this particular device is not great and moves around quite a bit. With a x10 post gain stage and software calibration I can resolve to about 1mA however day to day dc offset moves around by 10-20mA. I'm considering adding auto zero feature to the software, however I would prefer to just upgrade the circuit to something inherently more stable.I have looked at for example the INA186Ax series of Bidirectional current sense amplifiers and these would almost certainly yield better results and be less costly, the problem is that in some situations the circuit sourcing the current could have common mode voltage of up to 250Vrms.Any suggestions?

author: Wolfram
author_rank: Frequent Contributor
timestamp: January 20, 2021, 06:39:08 pm
content: Is the common mode voltage a static offset, or is there an AC component to it? If so, what sort of slew rates are expected?Isolated delta-sigma converters for current shunt sensing might be an option, if you can live with a delta sigma bitstream rather than an analog output signal. I've used the AMC1106 with success in the past.

author: CoteRotie
author_rank: Contributor
timestamp: January 20, 2021, 08:56:26 pm
content: Or if you want to stay analog you could look at the AMC3302 from TI. It has isolation AND an isolated DC-DC converter to power the input side of the amplifier.

author: Phoenix
author_rank: Frequent Contributor
timestamp: January 20, 2021, 09:08:53 pm
content: Quote from: CoteRotie on January 20, 2021, 08:56:26 pmI'm using an AMC1300B in a product I'm developing (inverter current measurement) for current shunts and I'm quite happy with it. the AMC3302 is similar and with built in isolated power supply.

author: jbb
author_rank: Super Contributor
timestamp: January 20, 2021, 11:20:09 pm
content: LEM make some newer devices - maybe the CKSR? range would help.
AC/DC power input, fusible flameproof resistor in SMD - Page 1
Forum section: electronics / projects

author: Mad ID
author_rank: Regular Contributor
timestamp: January 03, 2015, 04:32:36 pm
content: Hi,I'm designing an AC/DC Power supply based on LNK302 high voltage buck converter (12V @ 100mA).They recommend that for the input stage I should use, and I quote "The fusible resistor should be chosen as flameproof and, depending on the differential line input surge requirements, a wire-wound type may be required".In their designs they always use a 1W wirewound 8.2R THT resistor from VitroOhm (CRF253-4 8R2). I know that 1W is only for the surge immunity.I cannot find a suitable fusible flameproof resistor in SMD package. Why is that? I'm missing something or there aren't any?I want my design to be well designed, i.e. from functional and safety prospective.Thanks guys!

author: SeanB
author_rank: Super Contributor
timestamp: January 03, 2015, 04:48:53 pm
content: What is wrong with having 2 holes and using a through hole version, which is pretty common.

author: Mad ID
author_rank: Regular Contributor
timestamp: January 03, 2015, 11:29:47 pm
content: Quote from: SeanB on January 03, 2015, 04:48:53 pmFor manufacturing reasons I was hoping to find a SMD version.

author: Zero999
author_rank: Super Contributor
timestamp: January 03, 2015, 11:38:35 pm
content: Use a normal 1W resistor and put a suitable fuse in series with it.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 04, 2015, 01:10:20 am
content: Chip resistors are not rated for fusible duty, at least not normally as far as I recall seeing in datasheets.You can connect multiple in series to achieve the peak voltage rating, but I don't know that the result will be self-fusing in the same way.I would suggest not using SMT resistors at all, as they may fail before the fuse proper is able to open.You can use an NTC for surge reduction instead of the fusible resistor, but I don't know that these are normally available in SMT formats for this purpose, either. Probably for the same reason -- power, voltage and energy handling are necessarily all inferior.If this is a low quantity thing, you can do the half-ass solution and mount the part horizontally, soldered sideways to SMT pads. Lower profile I guess, but only more trouble than a proper THT solution.Tim

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 04, 2015, 01:17:02 am
content: At a glance, it seems Vitrohm at least has series such as RWS5020 which they state will clear when AC line voltage is applied. I do not see any mention of safety agencies in the datasheet, however.Tim
AC/DC power supplies with switching frequency synchronization - Page 1
Forum section: electronics / projects

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: October 18, 2018, 05:39:39 am
content: I'm looking for an AC/DC power supply that offers synchronization to an external frequency source. This seems like an option that's offered on DC/DC converter chips (eg: the LT8614 has a SYNC input). Has anyone has come across a similar option on off-line switchers? The only example I've found so far is theArtesyn iMP series. These are nice supplies, but have way too many bells and whistles and is too expensive for my application. Output voltages are 6V, 15V and -15V, current draws of a few amps per rail. Thanks.
AC/DC power supply 15W: flyback transformer design manufacturer - Page 1
Forum section: electronics / projects

author: logicnibble
author_rank: Contributor
timestamp: December 01, 2016, 03:27:24 pm
content: Hello!I am designing an AC/DC power supply using a flyback topology for up to 15W.Now I need to design the flyback transformer. I only know the transformer currents (peak, average, primary, secondary) and needed inductance.Do you know any good transformer manufacturer that can design this type of transformer based on the specifications I have, supplying some samples?Preferably in Europe.Thank you!

author: logicnibble
author_rank: Contributor
timestamp: December 07, 2016, 12:19:04 pm
content: Are there any flyback transformer designers out there that can help me?
AC/DC SMPS charge supercap bank - Page 1
Forum section: electronics / projects

author: r0d3z1
author_rank: Regular Contributor
timestamp: July 22, 2019, 06:20:23 am
content: Hi,I am looking for a AC/DC 300w to charge 36V 5F supercap bank and supply the load. It must be current regulated to work in CC during load absorption peak and CV when the load is low. I have find some battery charger from meanwell like the enc-360 but I think this kind of devices can't start to charge from 0V.Anyone have experience with this problems ?Is there some workaround to avoid the initial test that the battery charger usually do ?Anyone can suggest me a ac/dc that do what I need ?thanks
AC/DC Switching Network With NMOSs - Page 1
Forum section: electronics / projects

author: rerkilet
author_rank: Newbie
timestamp: February 02, 2024, 04:04:17 pm
content: Hello everyone, I'm currently working on a project where I need to switch a signal and introduce a resistive, capacitive, or inductive element to the circuit. I've connected the element to my second NMOS and, upon opening the switch, I'm trying to force current to flow through the selected element. In my research, I came across Solid State Relays (SSRs), and their internal circuit seems suitable for my needs. I verified this in LTSpice, and the results were promising.However, I'm facing challenges in physically implementing the circuit. I suspect that I need a differential probe to accurately measure the current on the "load" side. I just wanted to get a sanity check from you all. Any insights or suggestions would be greatly appreciated.I am attaching my design files and simulation results to this message, in this case, the DUT is the 1Ω resistor on board, I am also measuring the current across this resistor to see the AC/DC switching effect.Thanks a lot, and have a great day!

author: Terry Bites
author_rank: Super Contributor
timestamp: February 02, 2024, 05:58:07 pm
content: Like this.... The diode bridge steers the load current to keep the mosfet in its forward rejion.
Acetate or transparency printer sheets thickness - Page 1
Forum section: electronics / projects

author: akis
author_rank: Frequent Contributor
timestamp: May 18, 2015, 10:40:00 pm
content: I am looking for slighly thicker than average transparency film, what I have found is 0.135mm - do you know of any thicker? I would like to try even 0.4-0.5 mm thickness.
Acorn 180 pcb T565 - Problem. - Page 1
Forum section: electronics / projects

author: ale112002
author_rank: Newbie
timestamp: January 01, 2019, 02:46:53 pm
content: Good morning I'm Italian I have a problem with this stairlift, it has completely shut down and I managed to bring it manually to the charging point only that now does not go down anymore, probably it should be programmed know the procedure?The electronic board has no switch is the T565 model. This is link of the pcb board:https://www.ebay.ie/itm/Acorn-180-T565-PCB-Board-from-working-Stairlift/302915135573?hash=item4687262855:g:FI0AAOSw8MZbvNyO