hybridfree/eevblog-posts huggingface dataset:
2x single rail PSU to make a dual rail PSU. - Page 1
Forum section: electronics / beginners

author: @rt
author_rank: Super Contributor
timestamp: January 25, 2017, 06:38:49 am
content: Hi GuysAny problem with that?Basically to use a pair of identical single rail variable bench supplies plugged into the same mainswith their output grounds tied together to provide a dual rail output?I can’t think of a problem, but maybe I’m not considering something.Cheers!

author: jeroen79
author_rank: Frequent Contributor
timestamp: January 25, 2017, 09:03:36 am
content: No problem at all.Mind that if you tie the grounds (-) together you will have two positive rails.For a symmetric supply you need to tie one's + to the other's -.

author: tron9000
author_rank: Frequent Contributor
timestamp: January 25, 2017, 09:12:42 am
content: connect negative of supply 1 to positive of supply 2the positive of supply 1 will by V+the negative of supply 2 will be V-the voltage measured between V+ & V-, should be twice the output of each supplyuse the connection made in 1. as your 0V for your circuit.measuring from V- to 0V you should see a negative voltage and from V+ to 0V and positive voltage

author: @rt
author_rank: Super Contributor
timestamp: January 25, 2017, 01:22:50 pm
content: Dual rail might suggest one supply is negative, I don’t know. In my case both are positive.Didn’t think there was a problem.+12V, +5V, 0, for retro computing. A number of computers that have no -12V supply needed, and a distribution block with all the fuses.It just appears I can go a little higher quality for cheaper if both supplies are single rail.Cheers
3.15A fuse in a 100W PSU - Page 1
Forum section: electronics / beginners

author: 9Rune5
author_rank: Newbie
timestamp: October 01, 2022, 03:19:09 pm
content: This week my Synology DS918+ NAS fell quiet. Its 100W PSU had given up the ghost and tripped my circuit breaker.It is beyond my current skill level to repair. But I was curious about what I found rattling around inside: The cover of a 3.15A 250V fuse. Looks exactly like the one found here:https://www.centiot.com/solid-state-square-body-t2a-250v-slow-blow-miniature-fuse-392-series-lcd-tv-power-boardIf I found the right specs, this is a slow blow fuse. Which I can kind of understand since the NAS contains four hard drives. OTOH, the NAS powers up the hard drives in sequence, thus keeping the power spikes to a minimum. But 3.15A? That hints at an input of 787W? Is that fuse not a tad too big for this PSU?Sidenote: This was a PGB branded PSU. Later models are adorned with Synology's own logo and I found a forum post claiming that there had been issues with the old PSU. In any case, since Synology's PSU cost four times more than an ATX PSU, I simply bought an ATX PSU that can easily supply 200W+ on its 12V rail. It handles my NAS without breaking a sweat.

author: wraper
author_rank: Unknown
timestamp: October 01, 2022, 03:31:55 pm
content: Fuses rarely blow up by themselves. You have severe burn marks on the bottom side of PCB. As to why fuse is oversized, it's due to high inrush current when device is plugged into mains socket.

author: madires
author_rank: Super Contributor
timestamp: October 01, 2022, 04:19:15 pm
content: There are tons of 12V power bricks with a reasonable price-performance ratio to choose from, e.g. Meanwell.
3.3-24V -> 3.3V 1A Power supply reference design - Page 1
Forum section: electronics / beginners

author: gcardinal
author_rank: Unknown
timestamp: January 04, 2022, 02:49:54 pm
content: I'm looking for a power supply reference design. Requirements are as follows:- Vin 3.3-24V- Vout 3.3V or 5V with at least 1A- Compact with small component count- Small footprint > priceI originaly considered TPSM63603 from TI (https://www.ti.com/product/TPSM63603) - however it requeres 3.95V to power up.It should be possible to power finished device from 1 cell LiPo and from a domestic LED driver power supply - usually 24V in Norway.Thanks!

author: drdm
author_rank: Contributor
timestamp: January 04, 2022, 03:21:10 pm
content: You either need a SEPIC, or a buck with a "100% PWM" option like this one:https://www.ti.com/lit/ds/symlink/tps629210-q1.pdf?ts=1641275301565&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPS629210-Q1That is if your output does not go higher than the input.Also the LiPo battery cell is 3.7V at 10% charge, which makes it possible to use a regular Buck, if you so wish.In general, one of the more "fancy" Bucks that can transition between PWM and PFM modes and is optimized to work at low loads would be fine, but that's a Mouser search, that you shall embark on alone

author: Terry Bites
author_rank: Super Contributor
timestamp: January 05, 2022, 01:53:45 pm
content: https://www.ti.com/design-resources/design-tools-simulation/webench-power-designer.htmlopen an acount and have a go.
3.3 Volt regulator output on external connector - Page 1
Forum section: electronics / beginners

author: rakeshm55
author_rank: Regular Contributor
timestamp: May 11, 2019, 12:17:16 pm
content: Hi,I have a 3.6V rail available on my board.I have a GPS module (XM1100) which needs an active antenna . I plan to have an LDO (LP5907MFX-3.3) to generate 3.3V.Now the antenna port is mounted on external chassis. So the LDO should be hardened enough to handle handling abuse short,Surge,etcIs there a suitable LDO for such applications??

author: t1d
author_rank: Super Contributor
timestamp: May 11, 2019, 04:17:56 pm
content: Well, as a general answer...1) You need to know if...- The PSU can supply the additional needed amperage, which shouldn't be very much- The rail trace can handle the extra loadAs you are likely to need various components to round out a PSU sub circuit, you may want to make an independent sub PSU board and tap directly to the supply (transformer, etc.). But, again, can the supply handle the extra load? Is the supply the proper type; not a buck converter, for certain types of sub circuits, etc...More information as to the host unit, its supply, etc. and the the GPS power requirements would help.Are you making a GPS time discipline? If so, look at existing DIY project modifications. Skullcom has one on YouTube. There are many others.
3.3V for Accelerometers - Page 1
Forum section: electronics / beginners

author: cksa
author_rank: Regular Contributor
timestamp: July 23, 2010, 12:22:20 am
content: So I'm designing this portable device that incorporates accelerometers and gyros for inertial measurement purposes. This of course requires a precise and stable voltage supply to these components. However, I am stuck in thinking of how to achieve this whilst not using too many batteries.For example, I could use one AAA and boost it up to 3.3V, but will this be stable enough? Could I boost it up to say 5V and use a linear regulator to regulate it down to achieve less ripple? Since there are other devices on the 3.3V rail, would it be a good idea to use TWO separate 3.3v regulators, with one directly dedicated to the ADC and the accelerometers and gyro?I could also use one li-poly, but that requires a buck-boost or sepic DC-DC converter, again, switching regulators, will there be too much vout ripple?Thanks,

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 23, 2010, 03:27:16 am
content: the is no such thing as accuracy in navigation terminology unless u stick with GPS system... satellites & beacons = man made.... stars & landmarks = god made. i dont see the point of trying harder to design a bulletproof electronics hardware if its for the sake of accuracy, but if its for reliability,durability and quality... then yes! for me... a battery and a bypass caps will just do fine. no offense, but i'm a navigation system designer as well.... not professionally though, just hobbyit is for navigation isnt it? or positioning of some sort?

author: cksa
author_rank: Regular Contributor
timestamp: July 23, 2010, 03:31:50 am
content: Oh lol. It isn't for outdoor applications, so GPS wouldn't work. It's for a sports application very much indoors

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 23, 2010, 03:34:12 am
content: once you are done with the electronics part, the mechanical aspects will come into your way... then it goes to programming part, or circuit tuning part... and it will go merry go round and round until u satisfy... i think

author: marianoapp
author_rank: Regular Contributor
timestamp: July 23, 2010, 04:06:48 am
content: and when you finish and get something like this you know it was worth it

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 23, 2010, 04:25:15 am
content: hell! thats aggressive! last time i dealt with browned out mcu and motor kickback issue, several config of caps will do the trick, other than that, i only accept what gyros gave me. just keep focusing on what voltage level you are referencing at. and if its the voltage accuracy for the gyros you are worrying about, i suggest you wire it directly to the main power supply (with superb noise suppression of course!), with the stepped down/up voltage will feed the rest that dont need the accuracy. just my limited knowledge tells.
Amplify PIR 3.3V? - Page 1
Forum section: electronics / beginners

author: almamater
author_rank: Regular Contributor
timestamp: January 22, 2021, 12:49:32 pm
content: Hello Everyone!I want to make a simple circuit but now i have one question\problem. I want to control one LedStrip (40Leds \~450mAcurrent consumption) with one sensor PIRlike this oneand control one 5mm LED at same time, when LEDstrip is ON the LED is OFF and vice versa.This PIR have3.3V (Hight)at the Output Pin when motion is detectedSo, i made this circuit and works very well with myATX power supply(for simulate the 3.3V input):But now when i test with the PIR Output the circuit don't work, probably i have to amplify some how the 3.3V from the sensor, can you please help me with this? Probably i must put another transistor between the PIR and this circuit (BD139).. but what the best way to do it?Thank you.

author: Terry Bites
author_rank: Super Contributor
timestamp: January 22, 2021, 01:38:58 pm
content: Most of these little PIRs can only source 100uA or less from their output.The BD139 has a beta of ~20 so you will barely turn it on.Change it for alogic level mosfet. For example an NTR4501NT1G, it will handle 2A with very low drive requirements.

author: cavac
author_rank: Contributor
timestamp: January 22, 2021, 02:01:57 pm
content: Something like this should work, at least i think it should without actually building the circuit:

author: Zero999
author_rank: Super Contributor
timestamp: January 22, 2021, 04:41:48 pm
content: Quote from: cavac on January 22, 2021, 02:01:57 pmThe MOSFET's drain and source connections are reversed and why use two BJTs, when one will do?

author: cavac
author_rank: Contributor
timestamp: January 22, 2021, 06:36:59 pm
content: Quote from: Zero999 on January 22, 2021, 04:41:48 pmWhoops.Copied the MOSFET design from a recently finished project. Switched the pins on my PCB around after an ElectroBOOM moment but i guess i forgot to update my hand-drawn schematic. Well, uhm, it's good thing that the error popped up here in discussion, i would probably have just copied the design for my next project... and looked in wonderment at another smoking crater in the midst of my PCB...Quote from: Zero999 on January 22, 2021, 04:41:48 pmTerry Bites mentioned that the PIR can only source a tiny current, so i figured i'd better double up on those transistor to get better amplification of that tiny signal.

author: Zero999
author_rank: Super Contributor
timestamp: January 22, 2021, 06:42:13 pm
content: MOSFETs have a truly massive, almost infinite, current gain. One BJT is sufficient. The only reason to add more is to improve the switching speed, which isn't necessary in this instance.

author: cavac
author_rank: Contributor
timestamp: January 22, 2021, 06:46:30 pm
content: Thanks!

author: almamater
author_rank: Regular Contributor
timestamp: January 22, 2021, 11:29:04 pm
content: Thanks for the responses!! I will try and test the suggestions
3.3V to 5V logic level converter - Simple - or is it? - Page 1
Forum section: electronics / beginners

author: matt_c
author_rank: Newbie
timestamp: July 17, 2020, 11:03:41 am
content: I have a 3.3V microcontroller (SparkFun SAMD21 Mini) I would like to interface with the 5V logic inputs on a motor controller boardhttps://electromen.com/en/products/item/motor-controllers/brushless-dc-motor/EM-347A/The motor controller board inputs state they require 4V minimum. Plus these inputs have 10kΩ pull down resistors on some of them except speed and torque control which have 100k.I plan on using PWM for the speed and torque control.Which voltage level conveter would be most suitable?Originally I was going to go with a bidirectional MOSFET level shifter, with 1k pullup on the 5V side, however it's a lot of seperate components for the 4 channels I need (start, direction, speed, torque). So a single chip would be more convenient.I was thinking a 74HCT244 Buffer/Line Driver may work in one direction.Or perhaps txb0104 or txs0104, but I'm not sure would be able to drive the motor controller input above 4V with the 10k pull down resistors.What does everyone think?

author: Siwastaja
author_rank: Super Contributor
timestamp: July 17, 2020, 12:24:08 pm
content: Any 74HCTyou have around. A buffer obviously, or an inverter if you swap the polarities in software, and so on.These parts use 5V supply, and output 0V and 5V levels, being CMOS parts. T in the part name means TTL-compatible input levels, and with TTL input levels, 3.3V is reliably '1', which is exactly what you want.Special level shifters offer features like bidirectionality which you do not want here.For the analog inputs, you can RC filter the PWM, but the response won't be fast. I'd assume they filter the inputs on the motor controller, as well, though, to prevent torque ripple caused by noisy inputs.

author: David Hess
author_rank: Super Contributor
timestamp: July 18, 2020, 12:34:51 am
content: 74HCT logic would be the simplest although technically any 5 volt TTL logic should work with a pull-up on the output. A common base bipolar transistor with pull-up would also work fine. I have sometimes used optocouplers for level shifting which has the advantage of galvanic isolation.
3.3Vin 1-15Vout - Page 1
Forum section: electronics / beginners

author: kcs
author_rank: Regular Contributor
timestamp: December 01, 2014, 07:35:22 am
content: I am looking for a solution how to get adjustable voltage by 1V increments in a range of 1 to 15V that is going to be done with a microcontroller.Requirements:- Vin = 3.3Vdc- Vout = 1-15Vdc- Isw = 20mA- Iq <= 2mA- Efficiency >= 50%I was searching for step-up/step-down DC-DC converter with I2C control. However, could not find anything that matches my requirements. So, I am thinking of doing the following:1. Use fixed step-up DC-DC converter to get ~18V from 3.3V2. Use adjustable step-down DC-DC converter to be able to get 1-15V out of 18V3. Use digital potentiometer that is controlled over I2CIs there any more elegant solution that anyone could recommend me? And by "elegant" I mean something that has better efficiency, less external components and is less complicated.

author: wraper
author_rank: Unknown
timestamp: December 01, 2014, 08:34:26 am
content: Quote from: kcs on December 01, 2014, 07:35:22 amSepic converterhttp://www.ti.com/lit/an/snva168e/snva168e.pdf
3.5inch display with good viewing angles - Page 1
Forum section: electronics / beginners

author: symbianas
author_rank: Regular Contributor
timestamp: May 17, 2020, 06:39:23 pm
content: Hi, I bought this3.5inch TFT Arduino UNO Display, but its viewing angles are relly bad if I put display horizontaly, I think its viewing angle is 12oclock and I guess I need 9oclick viewing angle, since I plan to add it to car horizontaly. Is there any better display with same dimensionsions? Oled? Or 9oclock viewing angle?

author: Raj
author_rank: Frequent Contributor
timestamp: May 23, 2020, 07:30:59 am
content: Oled and e paper have good viewing angles... But do know, oled might have problem with Sun glasses
3.5mm Audio jack disconnect pins? - Page 1
Forum section: electronics / beginners

author: trevorford
author_rank: Contributor
timestamp: August 18, 2015, 04:42:05 pm
content: I am trying to figure out what all the pins do on these audio jacks, this is the best answer i can find (https://www.adafruit.com/products/1699) but I'm still unsure on what it means or what the pins do. Any help would be appreciated.Thanks,Trevor

author: tooki
author_rank: Super Contributor
timestamp: August 18, 2015, 07:16:05 pm
content: Quote from: trevorford on August 18, 2015, 04:42:05 pmBasically, it means that the jack is capable of routing the sound to a speaker when nothing is plugged in, and then disconnecting the internal speaker when you insert a plug. Think of it as having 5 pins:GroundL inR inL outR outWhen no plug is inserted, sound comes out the Out pins. When a plug is inserted, the Out pins are disconnected.There are jacks that actually have independent insertion detection switches, but I don't think that's the kind you're likely to encounter as a hobbyist.

author: matseng
author_rank: Frequent Contributor
timestamp: August 19, 2015, 03:25:58 am
content: Audio jacks are evil. Or at least I'm too stupid to read the datasheet right...After being burnt by using the wrong pinsin a few PCBs when I just looked at the datasheet and symbol in the schematics I've vowed to only use audio jacks that I have in stock in my lab where I can verify which pin that goes where and exactly how the disconnect/connect functions work.

author: Richard Crowley
author_rank: Super Contributor
timestamp: August 19, 2015, 04:39:45 am
content: The schematic diagram in the cited PDF seems quite clear. Not sure what all the confusion is about?The diagram shows:(1) Sleeve(2) Ring(3) Ring switch(4) Tip switch(5) TipThe pins (1) Sleeve, (2) Ring, and (5) Tip connect directly to the plug.The ring switch (3) counects to Ring (2) when there is nothing plugged in.And the tip switch (4) connects to Tip (5) when there is nothing plugged in.In traditional circuits, the ring switch (3) connects to the internal right channel speakers,and the tip switch (4) connects to the internal left channel speakers.That way the speakers are automatically disconnected when you plug in the headphones/earbuds or whatever.

author: tooki
author_rank: Super Contributor
timestamp: August 19, 2015, 09:24:36 am
content: Oh for crying out loud, how did I miss the datasheet link?So yeah, replace my answer with Richard's perfect description.
3.6 V Li - Ion/Li-Po battery switching and charging circuit - Page 1
Forum section: electronics / beginners

author: RPBCACUEAIIBH
author_rank: Contributor
timestamp: May 18, 2013, 03:29:44 pm
content: I'm trying to design a circuit which switches my other circuits between adapter and battery power, without interruption, charges the battery, and also stops when it is charged, and I came up with this.It will be probably be used with some Li - Ion/Li - Po battery(a bigger one, that can supply about 1 A for a few hours). This is the lowest cost smart charger that I could came up with so far... I have made one more with an ATTINY microcontroller, but that's a little overkill I think... This should do what I need it's simple, cheep, and doesn't require any program to work.Switching: When the Adapter is connected R2 set 4.8 V to the Q1's base which is normally pulled down, causing Q3 to turn off, while the IC1starts to supply the necessary current for the circuit.Charging: IC2 Supplies current to the charger circuit so that is not powered when the device is powered from battery R7 sets the upper limit which stops the charging, R8 sets the lower limit under which the charger turns on. Between the 2 limit the battery is full. The 555 timer is used to switch the charging on and off. For setting the charging current the R4 should be changed.The circuit is not tested yet, but I thought I share it. I'll replay when I test it, but that will be a little further, because I already have a charger, this just came to my mind while I was working on another project.

author: Crockett
author_rank: Contributor
timestamp: May 18, 2013, 04:00:46 pm
content: This is more the direction I was looking at for my 9-Volt charger/supply. I like the LED circuit posted there, but question I have on that is whether it cuts off charging when the battery is fully charged.Thanks for posting this thread.

author: Paul Price
author_rank: Super Contributor
timestamp: May 18, 2013, 04:25:56 pm
content: The 9v LED regulated charger stops charging when the battery if fully charged, at which point it will give the battery a tiny trickle charge(a few mA at most).

author: Crockett
author_rank: Contributor
timestamp: May 18, 2013, 05:25:09 pm
content: Thanks, Paul.Now I still want to see what else I can do with this; I'll return to my thread for that.
3.7v Battery Charging module  - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: November 12, 2024, 03:48:51 pm
content: I'm attaching a very common available batter charging module picture here,I want to know if anyone has study it and found it quite safe to use??I'm looking to charge 3.7v (between 1 to 3Am) Lithium battery

author: tunk
author_rank: Super Contributor
timestamp: November 12, 2024, 04:04:03 pm
content: There's a review here by EEVblog member HKJ (without the protection part):https://lygte-info.dk/review/Review%20Charger%20TP4056%20UK.html

author: sairfan1
author_rank: Frequent Contributor
timestamp: November 12, 2024, 04:42:14 pm
content: Thanks for sharing but that modules is a bit different.

author: Peabody
author_rank: Super Contributor
timestamp: November 12, 2024, 05:19:15 pm
content: The module is different in that yours includes a protection circuit (DW01) that prevents over-discharge, etc. But the charger chip - the TP4056 - is the same on both, so the HJK analysis will apply to your module. HJK's module is used when the battery has its own protection circuit. Does your battery have protection built-in?Your module is very widely used, and as far as I know it is reliable and safe. By default the charge current setting resistor is 1.2K, which produces 1A of charge current, which is the maximum the chip can deliver. For smaller batteries, you may need to change that. The TP4056 datasheet has a table showing the current produced by various resistor values.I think the modules now come with a variety of USB connectors, including USB-C. So you would need to decide about that, and whether you want the protection circuit in the module.

author: Kim Christensen
author_rank: Super Contributor
timestamp: November 12, 2024, 05:36:21 pm
content: I've used what looks to be the exact same one as yours. They work OK with no problems.The only thing I noticed, and this has nothing to do with the little PCB itself, is that the voltage drop in the USB cable is a limiting factor on max charge current.ie: Even though the charge current setting resistor is 1.2K, you won't get the full 1A charge current due to voltage drop in the USB cable. This is especially true as the battery voltage rises.Picture of one I used:

author: kjr18
author_rank: Regular Contributor
timestamp: November 12, 2024, 05:54:10 pm
content: Quote from: Kim Christensen on November 12, 2024, 05:36:21 pmIt depends what you use as power supply, some usb chargers put out a little higher voltage when loaded with higher currents, to minimalise voltage drop. Also TP4056 datasheet mentions small value resistor just before chip, probably to reduce heat.
3 stepper motors - Page 1
Forum section: electronics / beginners

author: waspinator
author_rank: Contributor
timestamp: January 16, 2017, 03:37:41 am
content: Hi,I'm looking at using 3 phase stepper motors, but I can't find much information about them. How much harder are they to drive? I've only found $100 CNC type drivers online, but they're not mentioned much in hobby community. Allegro makes a SI-7600 3 phase stepper driver, but there doesn't seem to be stock or breakout boards. Where should I be looking to find more information?http://www.alldatasheet.com/datasheet-pdf/pdf/38283/SANKEN/SI-7600.htmlhttps://en.wikipedia.org/wiki/Stepper_motor#Higher-phase_count_stepper_motorsThanks

author: ebclr
author_rank: Super Contributor
timestamp: January 16, 2017, 04:35:54 am
content: Driverhttp://www.onsemi.com/PowerSolutions/evalBoard.do?id=STK673-010GEVB

author: rstofer
author_rank: Super Contributor
timestamp: January 16, 2017, 05:08:56 pm
content: Stepper motors come in a lot of sizes and one thing that distinguishes them is motor current. You didn't say which motor you are using so it is impossible to help select a driver. There's a reason that large commercial drivers tend to be used on CNC milling machines. The motors are drawing somewhere between 5 and 10 amps and we also want a bunch of microsteps.OTOH, if microstepping isn't required and motor current is modest, you can drive the motor with some MOSFETs hung off the side of an Arduino. Or maybe just an L293D driver chip (or similar):https://learn.adafruit.com/adafruit-arduino-lesson-16-stepper-motors/overviewhttp://arduino.stackexchange.com/questions/20503/can-an-l293d-motor-driver-shield-do-microstepping
3-chip microcomp-1 - Page 1
Forum section: electronics / beginners

author: Simon123
author_rank: Regular Contributor
timestamp: August 24, 2011, 12:30:27 pm
content: can somebothey please send me schematic for 3-chip?picture (bw):http://www.rebelhosts.com/tt/te/images/p101.jpg

author: EEVblog
author_rank: Unknown
timestamp: August 24, 2011, 12:34:46 pm
content: Colin Mitchell at Talking Electronics has all the info, and can probably still sell you the mags and a kit maybe.www.talkingelectronics.comTell him I sent you.Dave.

author: joelby
author_rank: Frequent Contributor
timestamp: August 24, 2011, 12:38:35 pm
content: Ha! That brings back memories. I'm sure I have a copy of that magazine issue stashed away somewhere. I've got a Tek-1B in the shed.

author: joelby
author_rank: Frequent Contributor
timestamp: August 24, 2011, 12:55:04 pm
content: Anyway, is there any particular reason why you'd want to build one of these? They are very simple, and there should be dozens of comparable Z80 single board computer designs kicking around on the Internet.From memory it was a simple oscillator (either using inverters or a transistor multivibrator), a 2732 EPROM, and 74LS374 latches for I/Os. The Tek-1 also used a 74LS138 to decode ports - the Microcomp might not have bothered with the latter for simplicity.

author: Simon123
author_rank: Regular Contributor
timestamp: August 24, 2011, 02:44:34 pm
content: i want build it beacuse its cool (i watched demo of this comp)

author: Simon123
author_rank: Regular Contributor
timestamp: August 24, 2011, 02:45:52 pm
content: Quote from: EEVblog on August 24, 2011, 12:34:46 pmi just wana sch. not the mag.

author: Simon123
author_rank: Regular Contributor
timestamp: August 24, 2011, 02:50:27 pm
content: Quote from: joelby on August 24, 2011, 12:38:35 pmcan u send me the scan of sch and descr. if you find the mag. ?

author: joelby
author_rank: Frequent Contributor
timestamp: August 24, 2011, 03:11:21 pm
content: It'll be somewhere at my parents' house, and I'm currently in a different state.. so maybe, but it'll take me a while to get around to it. I don't think the code for the EPROM was printed in the magazine, so you might have to ask Colin Mitchell about that regardless. Without this, it will literally do nothing.

author: Simon123
author_rank: Regular Contributor
timestamp: August 24, 2011, 03:25:09 pm
content: tnx

author: EEVblog
author_rank: Unknown
timestamp: August 25, 2011, 05:14:00 am
content: Quote from: Simon123 on August 24, 2011, 02:44:34 pmThen the schematic ain't going to help you unless you have the firmware to go along with it. The articles are excellent, they are worth getting.And it's only fair to pay a few bucks to Colin for his work. he might even have a kit (or the PCB) to make it easy for you to build.Dave.
3 input Buzzer FGM question[solved] - Page 1
Forum section: electronics / beginners

author: typematrix
author_rank: Contributor
timestamp: January 16, 2019, 04:52:35 pm
content: HiI found this buzzer in a carbon monoxide alarm I was throwing out.Must be 10 years old or so It was powered by 3-4 AA batteries.Its has 3 pins marked F G MMarkings (Made IN Korea by SUN JIN) no part number.I am trying to make itbuzz, want to add to an alarm i am making.I been doing a bit research and found this circuit, I set it up but nothing happened.https://electronics.stackexchange.com/questions/18212/whats-the-third-wire-on-a-piezo-buzzerAny links or ideas here , The buzzer in the alarm was working before I took it apart.thankslinks to image of buzzer.

author: Wimberleytech
author_rank: Super Contributor
timestamp: January 16, 2019, 05:00:29 pm
content: Quote from: typematrix on January 16, 2019, 04:52:35 pmThat is the correct circuit. It should work. Once wired, have you varied the power supply to see where oscillation starts? Show us your circuit...Also try increasing the collector resistor to, maybe, 2k or so.

author: soldar
author_rank: Super Contributor
timestamp: January 16, 2019, 05:00:57 pm
content: I googled three terminal buzzer and foundhttps://electronics.stackexchange.com/questions/18212/whats-the-third-wire-on-a-piezo-buzzer

author: typematrix
author_rank: Contributor
timestamp: January 16, 2019, 05:31:05 pm
content: I got it working by changing the resistor values as suggested.Thanks
3 legs, sot23, 4KAL markings - Page 1
Forum section: electronics / beginners

author: u666sa
author_rank: Frequent Contributor
timestamp: October 04, 2023, 10:14:43 pm
content: What is it? Most important thing is how to test it.Marking is 4KAL.

author: Dan123456
author_rank: Regular Contributor
timestamp: October 05, 2023, 12:55:07 pm
content: What’s the application for this one?I had a quick look and am getting a couple of possible hits but doubt they are relevant(?).One is on 80’s military electronics (which is like 400 pages long so didn’t want to go digging through that without knowing I am looking in the right spot) and the other 2 are declassified CIA documents (I’m not even joking)!!!I didn’t end up clicking all the way through on those ones to check them out as figure I am probably on enough watch lists as is

author: wofritz
author_rank: Contributor
timestamp: October 05, 2023, 01:15:19 pm
content: Closest I found is this:http://www.union-ic.com/Upload/Datasheet/Datasheet_UM1431,UM1441_Rev01.pdfThat's a linear voltage regulator (4KA: 2V)Does that make sense?

author: u666sa
author_rank: Frequent Contributor
timestamp: October 05, 2023, 02:11:26 pm
content: Quote from: wofritz on October 05, 2023, 01:15:19 pmYes, this hit makes perfect sense. Though I still wonder what is that L at the end, more precisely for the next time, do I drop the L and search for 4KA without L to get a proper hit.Anyway, I've already tested it by removing it and powering up and making some measurements, without it PSU did not work, hence it must be alive. I wonder how one would test this using digital multimeter? Let's assume it is out of circuit..

author: cortex_m0
author_rank: Regular Contributor
timestamp: October 06, 2023, 12:00:17 am
content: On small IC markings, often they have a letter for a date code, lot code, or manufacturing site. That's probably what the L is here.

author: Shonky
author_rank: Frequent Contributor
timestamp: October 06, 2023, 01:55:12 am
content: Quote from: u666sa on October 05, 2023, 02:11:26 pmNot a huge amount you can do with just a meter. Maybe compare against a known good if you had one.You could assume it is the regulator you think it is. Put a current limited supply and measure its output.Or just put it back in the board and test input and output voltages make sense. Perhaps measure input side on the board without refitting and see if that makes sense for the pinout.
3-phase BLDC motor driving frequency formula - Page 1
Forum section: electronics / beginners

author: daveatol
author_rank: Regular Contributor
timestamp: March 27, 2013, 01:20:15 am
content: Hi all,I found some 3 phase motors on scrap and was wondering how to work out the rotation speed based on the drive frequency. The motor has 63 coils and 56 magnets.. does anyone know the formula to calculate the number of electrical cycles to attain a mechanical cycle?Also, just showing my ignorance, but what stops an RC ESC being used to drive a larger motor? Is it just the rotation speed? e.g. could a 60A, 25V ESChttp://www.ebay.com.au/itm/160631159669be used to drive a 24V BLDC motor?Thanks.PS I did ask this on another forum a week back but couldn't get the answers I was after.

author: peter.mitchell
author_rank: Super Contributor
timestamp: March 27, 2013, 12:33:29 pm
content: generally, RC based ESCs have a pretty tight frequency range, designed for 2-4-6 pole motors, if you use them on a high pole motor the motor won't spin very fast and the ESC may not be able to accurately judge the position of the rotor form the back EMF.Also, to a certain extent, on BLDC motors, the "voltage" doesn't matter; provided you don't overload the motor or go outside its RPM range, it will most likely be fine

author: daveatol
author_rank: Regular Contributor
timestamp: March 28, 2013, 09:03:36 am
content: Thanks for the reply Peter. So the problem may be with the drive frequency and feedback at low RPM.Would you happen to know how to calculate the RPM from the number of coil triplets and magnet pole pairs?
3 phase generator problem - Page 1
Forum section: electronics / beginners

author: ching90
author_rank: Newbie
timestamp: August 04, 2016, 10:30:29 am
content: I bought a new 3 phase generator from online shop.It is used to transform 220V 50Hz to 3 phase output.However, it dosent work on my household electrical product.Then, i use my CRO and found out below phase to phase voltage like below.Is it a correct traditional 3 phase waveform of phase to phase?

author: Jeroen3
author_rank: Super Contributor
timestamp: August 04, 2016, 02:03:18 pm
content: That is a 3-phase motor drive. What are you powering?Yes, that waveform looks normal. Especially open circuit. You're having some common mode noise though. Is your scope properly isolated?

author: ching90
author_rank: Newbie
timestamp: August 05, 2016, 01:16:17 am
content: Quote from: Jeroen3 on August 04, 2016, 02:03:18 pmThanks, Jeronen!My purpose is used to drive a 3 phase motor, but the motor seems not work. I checked the motor is work on my friend home.I am a totally a newbie of 3 phase. You are right! The Phase to Phase waveform measured under open circuit. It is interesting and difference to my 3 phase concept~ And i cant find any 3 phase waveform from online website like thisThe scope is handheld type, so i think it should not a common mode reject problem. Am i right?Do i need to set anything of the generator? Because there is some parameter called Center voltage, center frequency.

author: Jeroen3
author_rank: Super Contributor
timestamp: August 05, 2016, 05:25:52 am
content: Quote from: ching90 on August 05, 2016, 01:16:17 amWhen you buy a real motor drive. The unit will ask, or the manual will tell you to complete at least the basic operation parameters:- Nom speed, and there the speed ref comes from. (ext 4-20ma, 0-10V or front pot)- Nom current.- Non voltage.- Non cosphi.And thing like that you can read from the plate.RTFM.There area lotof parameters in these things. And therefore I highly recommend not to buy them from a random eBay seller.Does the motor make any audible screeching noise, since that would indicate current is flowing. It will use somewhere between 4 to 16 KHz as switching frequency, probably 4 by default (least derating, maximum audible screeching noise).
3 phase matrix - Page 1
Forum section: electronics / beginners

author: midasgossye
author_rank: Contributor
timestamp: April 29, 2013, 06:11:28 pm
content: Can anyone help me with the following problem please?Recently, I took an old external CD player apart. I hacked the draw opening system and hooked it up to an arduino with a motorshield.Also I wanted to control the "spindle". The motor that spins the CD.After some research I discovered it was a small 3 phase motor.The chip that was driving this used a 3 phase matrix. Chip N° BD7902FS (datasheet in attachment)I don't know what that means.Is it possible to drive this kind of motor with an arduino?Greetings,Midas

author: codeboy2k
author_rank: Super Contributor
timestamp: April 30, 2013, 07:18:59 am
content: These are just DC brushless motors with 3 windings in the body of the motor, and permanent magnets on the shaft. Each winding is driven by a PWM signal, and the PWM signals are out of phase, i.e. one signals leads the next signal which leads the next signal. This causes a rotating magnetic field around the core, which pushes on the magnets of the shaft and cause it to rotate. The speed and direction of rotation are controlled by the pwm and the order in which the windings are energized.The phase matrix is simply a 3-phase full-bridge controller consisting of 6 MOSFETs. This lets the controller provide acceleration torque and deceleration torque in both forward and reverse directions. This is known as 4 quadrant operation.There are many different algorithms for controlling the 6 pwm signals needed. You should read up on 3-phase DC motor control theory and about the PWM algorithms in particular. The algorithms cover the wave shapes, the transition times, PWM frequencies, etc... everything needed to get the motor going in the direction you want at the speed you want with the amount of torque needed.Whether or not you can control this with the Arduino depends on the arduino having a 3-phase full bridge and 6 available pwm outputs. Or a shield for that. I don't know anything Arduino so I can't help there.
3-Φ phase reversal detection logic - Page 1
Forum section: electronics / beginners

author: khatus
author_rank: Regular Contributor
timestamp: September 06, 2020, 09:00:20 pm
content: hello guys this the flow chart for 3-Φ phase reversal detection.My question is why they use the logicif captured time(T) in between 3 mesc and 8 msecIs that for (3+8)/2 = 5.5 msec??It is not clear to me.In my country the frequency is 50Hz so what should i take??Can i take 4msec and 9.32 msec?? So that (4+9.32)/2 gives 6.66 msec??

author: ledtester
author_rank: Super Contributor
timestamp: September 06, 2020, 09:31:13 pm
content: Let's consider a 60 Hz system.In one direction the time between the L2 and L3 zero-crossings will be close to 5.5ms.In the opposite direction the time will be 16.66 - 5.5ms = about 11ms.So if you allow a 3 to 8 ms window you will comfortably discriminate between the phases going one way versus the opposite way.For 50 Hz the times are 6.66ms vs. 20ms - 6.66 = 13.3ms. Again, the 3 to 8 ms window allows for some variance in timing while still giving a large margin for telling the difference between the forward and reverse modes.
3 pin scanner inverter - Page 1
Forum section: electronics / beginners

author: klayus
author_rank: Newbie
timestamp: November 18, 2014, 12:17:43 pm
content: Can anyone help me? I've taken apart a konica copier machine and i salvaged among other things this lamp with its inverter.the problem is the inverter has 3 pins on the input. by following the traces to the capacitor i've found which one is the + and the ground but i cant figure out whats the 3rd (middle) pin and the lamp dosen't start! it dosent draw any current either.i gave it 15V on the + and middle pin, i even put the middle pin to ground, but nothing happens.i didnt try giving it the full 24V as all of my other scanner light inverters start with less than their full voltage.here are some pics:please helpthanks in advance

author: Paul Price
author_rank: Super Contributor
timestamp: November 18, 2014, 04:30:00 pm
content: Check F1, the fuse.

author: klayus
author_rank: Newbie
timestamp: November 18, 2014, 06:11:17 pm
content: I bypassed it and it still dosent turn on

author: Paul Price
author_rank: Super Contributor
timestamp: November 18, 2014, 10:54:18 pm
content: Did you retry grounding or pulling up the center lead again?Was the scanner lighting up before you took it apart, showing the inverter was ok?Try to find a specsheet for the IC.I can see the inverter IC abd it just doesn't look like it requires a special signal on the middle connector pin, there are not enough pins on this chip or the power connector. There are usually other pins used for clock/data/enable functions.Some scanner inverter chips do use a serial bit stream to send control commands to set brightness/on/off. .just a hunch this is the case, the specsheet tells the full story. I cannot make out the IC Mfg. part # to check this, it is up to you.The most common failures of these inverters is HV arc-over that destroys the inverter transformer and this due to failure of the lamp it is connected to.I cannot see on the bottom of the PCB any connection from the connector center wire to any other part of the circuit. The pin's trace seems to end near the fuse.

author: klayus
author_rank: Newbie
timestamp: November 19, 2014, 05:25:56 am
content: The middle pîn goes to a leg of a transistor but I can't figure out what happens after it. The ic is a 10393 comparator so i'm guessing there should be some voltage on that pin to maybe set the intensity of the light. I'll try with a pot and see where that takes me.I'm pretty sure it was working as I have another one with a similar inverter, 3 pins, and I can't start that one either. That one has a pc494 inverter controller on it.Any other opinion is greatly appreciated.L.E. i tried with a pot the wiper feeding the middle pin and nothing happened. i'll try with pwm on that pin see where that takes me.

author: klayus
author_rank: Newbie
timestamp: November 22, 2014, 07:50:27 am
content: I got it working! The middle pin has to be put to ground through a current limiting resistor after the circuit starts.http://i62.tinypic.com/1448ozl.jpg[\img]thanx for your helpbest regards
3 port directional coupler - Page 1
Forum section: electronics / beginners

author: maxcy
author_rank: Newbie
timestamp: July 28, 2020, 08:57:55 pm
content: I'm thinking of buying a directional coupler to connect my signal generator to my transceiver in a way that protects it just in case I accidentally do key the tx. I see 3 port couplers that have an input, output, and a 'couple' port. I am assuming that Ishould connect the signal generator to the output, the transceiver to the input, and really don't know what to do with thethird port. Maybe connect it to a dummy load? Anyone with experience with these units?

author: TimFox
author_rank: Super Contributor
timestamp: July 29, 2020, 10:17:27 pm
content: A 3 port "circulator" should couple power from each port to the next one in order. To protect port 1 against reflected power or on-purpose external power at port 2, the third port should be terminated in a dummy load that can handle the power from the source. Power from port 1 goes to port 2 (not to port 3), power from port 2 goes to port 3 (not to port 1), and the power from port 3 (zero if properly terminated) goes to port 1 (not to port 2). Connected this way, it is called an "isolator". Of course, the isolation available (e.g., "not to port 2") is finite, and you will get some unwanted coupling, which should be specified by the manufacturer.
3 position On/On/ON switch with 6 terminals: how to wire it? - Page 1
Forum section: electronics / beginners

author: twingall1
author_rank: Newbie
timestamp: October 04, 2023, 09:17:47 pm
content: Hi all,This is my specific switch: 1MD6T1B5M1QE SWITCH, SOLDER TAG, DPDT, ON-ON-ONIt's a toggle switch with 3 positions and 6 terminals underneath and marked 'ON-ON-ON'I hoped to be able to wire it so each position (left , centre, right) would connect a different leg of an RGB led, giving me pure red, pure green, pure blue.But, it seems that there is no way to connect so that at least one position doesn't share a terminal/ crossover, and the best i can achieve is green, blue, bright pink.Can anyone advise if i'm missing a trick here or if i simply need to go and buy some 9 terminal switches.Many thanks,T

author: ataradov
author_rank: Super Contributor
timestamp: October 04, 2023, 09:31:59 pm
content: If you use pin 2 as a common and connect pins 3 and 5 together, then you will get 3 connections In a position 1, the common would be connected to pin 6, in a position 2 it would be pin 4, and in a position 3, it would be pin 1.

author: twingall1
author_rank: Newbie
timestamp: October 04, 2023, 10:16:03 pm
content: Excellent, working perfectly. Thank you so so much for your help!All best, T
3 position switch is ON in OFF position - Page 1
Forum section: electronics / beginners

author: Legion
author_rank: Frequent Contributor
timestamp: July 06, 2014, 10:03:05 pm
content: I've got a 3 terminal, 3 position switch which I'm trying to use to switch two devices. Center position is off. Positions 1 and 2 should turn on devices 1 and 2, respectively. I can't get it to work though. In the off position, both devices turn on. The problem is there's continuity between all three terminals in the off position. Just a 0.8V drop between terminals.Why would this be labeled off if there's still a connection?

author: lewis
author_rank: Frequent Contributor
timestamp: July 06, 2014, 10:11:35 pm
content: Knackered switch

author: What_NZ
author_rank: Regular Contributor
timestamp: July 07, 2014, 08:11:26 am
content: Quote from: Legion on July 06, 2014, 10:03:05 pmWhat happens when you push Position 1 or Position 2, is there still continuity between all 3 contacts?

author: Psi
author_rank: Super Contributor
timestamp: July 07, 2014, 08:30:00 am
content: yeah, maybe its a 3 postion normally connected switch

author: SL4P
author_rank: Super Contributor
timestamp: July 07, 2014, 01:04:56 pm
content: How about the idea that the COM terminal is one of the outer pins?hat would mean - if you wired it as though the centre was off - then odd things would happen.Either the printing on the switch body, or a simple test with LED or multimeter ohms range will help you out. Or an oddball switch !

author: jmoreland79
author_rank: Regular Contributor
timestamp: July 07, 2014, 06:36:50 pm
content: I'd imagine the switch came from a specific device where the labeling on it matches up with the behavior.It may not be describing the "On/Off" state of the device, but perhaps a secondary function. For example, it could function as a dimmer on a lamp. Position 1 is 50%, position 2 is 75%, and "Off" means no dimming. If the switch was mounted in fixture and had "Dimmer" written above it, it would make sense.Probably not the best example, but you get the idea.

author: Legion
author_rank: Frequent Contributor
timestamp: July 07, 2014, 07:00:49 pm
content: Sorry to waste your time. It was my fault. I had wired it up in some ridiculous fashion. When it didn't work, I rewired it in other ridiculous ways. It was only when I wrote out the circuit on paper that I saw my mistake. Prior to working on this, I received some bad news of a personal nature and I think I was letting it distract me.