hybridfree/eevblog-posts huggingface dataset:
how does a slip ring work​ - Page 1
Forum section: electronics / projects

author: weedslipring
author_rank: Newbie
timestamp: March 12, 2025, 06:11:43 am
content: Slip Ring --A slip ring is a device used to transfer power, electrical signals or data between a rotating part and a stationary part. It is also called a collector ring, a conductive ring, a rotary electrical interface or an electrical rotary joint. The design of a slip ring allows one part of a device to rotate freely while the other part remains fixed, while ensuring a continuous electrical connection between the two.Slip rings mainly consist of two key parts: the rotor (rotating part) and the stator (stationary part). The rotor is usually mounted on the part that needs to rotate and rotates with this part; while the stator is fixed to the non-rotating part. The two parts are connected by precisely designed contact points, which can be carbon brushes, metal brush wires or other types of conductive materials, which contact the conductive rings on the rotor to achieve the transmission of current or signals. [SPAM LINK REMOVED]
How does a touch-dimmable lamp work? - Page 1
Forum section: electronics / projects

author: Maxlor
author_rank: Frequent Contributor
timestamp: January 14, 2014, 09:27:57 pm
content: While playing with a DCF77 receiver, I noticed that my suspended lamp prevents reception; with it off the receiver works perfectly. It is a halogen lamp that is dimmable; you can touch any metal part of it to dim it.This gave me the idea to probe the lamp casing with my oscilloscope, the result is however not what I expected: I'm measuring 119Vrms! I triple checked the probe and the scope settings, and both are in 10x mode, so I don't think I made a mistake in the measurement. And my multimeter reports the same. It's not mains voltage directly though, since that'd be 240V.When touching the lamp, I feel nothing at all, no zap or tingle, even with wet fingers. Vrms is reduced to 104V. As the lamp dims and undims, the noisy part of the signal gets smaller and bigger, but the overall amplitude doesn't change.I don't understand what's going on exactly, can someone explain it to me? If it's current limited, shouldn't the voltage drop right down to near 0 when I touch it?

author: Andy Watson
author_rank: Super Contributor
timestamp: January 15, 2014, 12:02:46 am
content: Quote from: Maxlor on January 14, 2014, 09:27:57 pmIt probably is derived from the mains through a high-value resistor. Probably something of the order of a few M ohms - since your scope and multimeter load the voltage to roughly half. Have you ever used a neon testing screwdriver? - It's the same principle. You have capacitance to ground - so you complete the circuit and a micro-ampre current flows. Sensation takes the order of 1mA (on average). Try running the back of your hand lightly over the surface of the lamp - it will probably feel as if it's vibrating - but only when you move your hand.
How does AC ATV regulator work? - Page 1
Forum section: electronics / projects

author: hal9001
author_rank: Regular Contributor
timestamp: March 17, 2021, 10:46:11 am
content: Whats the circuit inside 2 phase AC regulators for ATVs like the one in the picture? Are they efficient?All pictures have the regulators closed.

author: TheMG
author_rank: Frequent Contributor
timestamp: March 17, 2021, 01:27:21 pm
content: In such vehicles that typically have a permanent magnet alternator, the regulator is a shunt regulator. Literally just clamps the voltage to a max value, excess energy being dissipated as heat.Not very efficient at all but simple reliable and effective, and has negligible impact on the engine of the vehicle since it's a relatively low power alternator to begin with, and at lower RPMs the output of the alternator is often below the regulation point anyways.Often these shunt regulator modules will also have a separate DC regulator for battery charging output.

author: hal9001
author_rank: Regular Contributor
timestamp: March 18, 2021, 03:05:06 am
content: thanks!

author: floobydust
author_rank: Super Contributor
timestamp: March 18, 2021, 03:17:43 am
content: Small engines like moped and ATV use a shunt regulator which wastes the excess voltage as heat.Better designs use a couple SCRs as a series regulator, like the Kubota one.Thread on the subject with a few schematics:https://www.eevblog.com/forum/projects/ac-generatoralternator-charger-rs1105-replacement/
How does it work: Fluke 9010 Protection Circuit - Page 1
Forum section: electronics / projects

author: NivagSwerdna
author_rank: Super Contributor
timestamp: July 08, 2021, 09:53:04 am
content: I'm toying with the idea of making an in circuit tester like the Fluke 9010 Troubleshooter Pods and looking at the original design for inspiration/ideas/plagiarismThe Fluke Pod has the ability to sample the individual lines into a latch whilst driving/listening to them to diagnose failures such as stuck hi, stuck lo, shorted to another line on the same bus etc and additionally it has protection diodes , presumably to protect the pod.The protection diodes are connected to 4.3V hi and 0.7V lo supplies; I presume that is to ensure the protected signal can go between 0 and 5V when the diode drops are taken into account.The 4.3V supply (pulled up by a 200 ohm resistor to 5V) comes from a now long obsolete proprietary IC; likewise the +0.7V (pulled down by 200R to ground).Considering the +ve side... I presume the U10 device is meant to sink to keep the 4.3V at 4.3V even in the presence of a spurious voltage on the input.Now the POD specification suggests the protection is intended to protect at over/under voltages in the range +12V to -7V.So... if +12V were applied to the input then the 'Sink' needs to dispose of sufficient current (limited by the 100R) to keep the uP input at 5V?This is completely outside my knowledge...How would I implement the Sink behaviour? Sounds like the job for an Op Amp and a voltage reference?And the source? The same?Thanks in advance

author: NivagSwerdna
author_rank: Super Contributor
timestamp: July 08, 2021, 10:54:35 am
content: So... choosing an arbitary diode it looks like I need to sink the best part of 100mA to keep everything in line; the original had +/-5V and 12V supplies; I will only have 5V.
How does it work? - Page 1
Forum section: electronics / projects

author: wholder
author_rank: Regular Contributor
timestamp: December 02, 2018, 11:12:09 pm
content: I've posted a YouTube video that shows an interesting way to use the AVR RESET Pin as an Input without disabling it's ability to reset the processor, or the ability to program the chip via ISP. Can you figure out how it works? Consider yourself an advanced AVR programmer if you can.I'm sure this technique has been used many times before, but perhaps it's new to you and you'll have a use for it. If so, please leave a comment on the video.Wayne
How does Power Over Ethernet classing work ? - Page 1
Forum section: electronics / projects

author: drakejest
author_rank: Regular Contributor
timestamp: December 03, 2020, 06:40:56 pm
content: In this POE controller there is atableabout how to set up classification of my device. I think i understand the concept of classifying my PD device its to tell the the supply equipment the power demand the PD needs.The first that i would like to know is classification why there seems to be a minimum power for certain class ? e.g. PD class 3, 3.84W - 6.49W (min - max). What if the PD device idles down and eating a low 0.5W power? what wouldd happen then ?The second is what would happen if the PSE cant deliver the power requirement of the PD device, so the PD device is on a higher classification than what the PSE can deliver. Would power still be given to the PD device but only the highest it can go ? Where does the responsibility of protecting both equipment from damage due to lack of power ? Is it the job of the POE PD controller to outright not give power, or its further down the line where the POE PD controller send a signal to the microcontroller/processor that not enough power is available, or simply the PSE will just straight up not give power ?
How does that work? - Page 1
Forum section: electronics / projects

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 20, 2013, 03:47:48 am
content: http://www.hypereng.com/single_phase.htmlExact what do those do? They somehow reduce the inrush current without slowing down the starting process.

author: David_AVD
author_rank: Super Contributor
timestamp: July 20, 2013, 04:06:05 am
content: It doesn't say that it doesn't "slow down the starting process". The "full torque" is only after it's finished the soft start I'd say.

author: Marco
author_rank: Super Contributor
timestamp: July 20, 2013, 04:16:32 am
content: In the literature you can see the oscilloscope waveform and they say they use thyristors, so we can make a guess ... it's a plain Triac type controller, it first lets through a small part of the wave for one or two cycles to determine the impedance of the motor at stall speed, it uses that to determine the phase angle at which to trigger the triacs to hit the current limit, when the motor drops below the current limit the phase angle gets decreased until it hits 0 and the motor is in steady state operation.

author: kaz911
author_rank: Super Contributor
timestamp: July 20, 2013, 04:55:44 am
content: I seem to actually have one of them for my Dometic boat Air Condition- Box looks the same - just with Dometic label on it. Teardown on its wayI have not installed it yet as I want to document the process and document inrush current changes etc.

author: SeanB
author_rank: Super Contributor
timestamp: July 20, 2013, 05:32:57 am
content: Simple triac phase controller that limits current to a level then increases it with time ( set by a pot) till it is at full power. It likely does this on the phase and the start winding, measuring the voltage across the start winding to determine when the motor is at near full running RPM then allowing full power to flow. Simple to do with a pair of triac controllers that are then switched to full power after a preset time or when the start voltage is over 200V. As well it disconnects the motor when the mains is low, and probably has a timer in it to limit the number of cycles per hour or just provides an on delay from power application to do the same.3 phase ones do this on 2 of the phase windings, with the third being a pass through.
How does the external error amplfier feedback works?  - Page 1
Forum section: electronics / projects

author: Patrick66
author_rank: Regular Contributor
timestamp: December 17, 2023, 08:10:07 am
content: Hello everyone, can someone teach me how to calculate the values in the error amplifier feedback. I want to maintain a constant output current of 333mA. How does this system work and what are the equations to calculate the capacitance and resistance value to obtain my desired output current of 333mA? Thank you for your help and guidance in advance.

author: magic
author_rank: Super Contributor
timestamp: December 17, 2023, 08:22:30 am
content: LED current is simply V2/R7 because U2 is meant to make its IN- equal to V2, so it's already ~333mA nominal.The rest must be frequency compensation, related to the parts you haven't shown.

author: moffy
author_rank: Super Contributor
timestamp: December 17, 2023, 09:38:25 am
content: Quote from: magic on December 17, 2023, 08:22:30 amFor the fuller story see:https://www.eevblog.com/forum/projects/flyback-convert-for-consatnt-current-led-driver-in-bcm-mode/

author: Patrick66
author_rank: Regular Contributor
timestamp: December 18, 2023, 12:42:58 am
content: Thank you so much for the information. As for the frequency compensation do you have any relevant website or video regarding to this?

author: Patrick66
author_rank: Regular Contributor
timestamp: December 18, 2023, 03:39:48 am
content: Hello sir, I have one more question to ask, why is the inrush current of the primary side of the transformer issue solved after adding resistor R6 (33kohm) at the DCM sensing pin of the IC?
How does the IN instruction work on a processor like the Z80... - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: August 02, 2016, 06:46:14 pm
content: If it executed "IN 0x75,A" would it set the address lines to 0x75, data lines as input, and then cycle the "RD" pin? Would the device being addressed switch its data lines to output and set the value it wanted to output? Finally then in the next cycle the data would be captured and the "RD" pin would go inactive?

author: Len
author_rank: Frequent Contributor
timestamp: August 02, 2016, 07:11:35 pm
content: Yes, basically. There's also an /IORQ line that signals when the CPU is doing a I/O operation.This is explained in the Z80 User Manual:http://www.zilog.com/appnotes_download.php?FromPage=DirectLink&dn=UM0080&ft=User%20Manual&f=YUhSMGNEb3ZMM2QzZHk1NmFXeHZaeTVqYjIwdlpHOWpjeTk2T0RBdlZVMHdNRGd3TG5Ca1pnPT0=

author: dnwheeler
author_rank: Regular Contributor
timestamp: August 02, 2016, 07:20:06 pm
content: That is essentially correct. Also note, the differences between memory accesses and port accesses are that the Z80 pulls the /IOREQ line low for port accesses and /MREQ low for memory accesses, port accesses only use A0-A7, and the Z80 inserts an extra was state for port I/O (to allow time for the target to decode the address).You really should look at the timing diagrams in the Z80 datasheet to get the complete picture. It should be called "Input or Output Cycles".

author: alank2
author_rank: Super Contributor
timestamp: August 02, 2016, 07:22:09 pm
content: Thanks guys - I'll take a look at them!
How does the KSGER T12 station know which tip is inserted - Page 1
Forum section: electronics / projects

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 13, 2019, 03:43:57 pm
content: I was surprised to see ERROR flashing on my screen and I realized the thing needs to have tips enabled by model.I find this fascinating. How does it know which is which? Is there a heat resistant single wire EEPROM in there somewhere? Does it sense temperature digitally as well to get the most out of that single contact?

author: ebclr
author_rank: Super Contributor
timestamp: April 14, 2019, 03:41:30 am
content: No eeprom inside the tip, Probably a table on firmware, with some parameters

author: empeka
author_rank: Contributor
timestamp: April 14, 2019, 07:30:37 pm
content: It doesn't. You have to select tip manually (press the knob and turn it right).The reson you got ERROR message is most likely that every T12 tip i had required some "burn-in" time to start working.There is also no any reliable value you could measure to implement tip type recognition, I'm affraid.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 14, 2019, 11:30:23 pm
content: Yeah you're right I must have fooled myself. I just tried enabling and disabling tips and now it makes no difference.Very odd that such a menu exists, maybe it's for a more advanced tip type.I also noticed what you say now, every new tip either showserroror has erratic temperature readings while it warms up the first time.Oh well, still a good station IMO.

author: empeka
author_rank: Contributor
timestamp: April 15, 2019, 08:20:57 pm
content: QuoteThis menu allows you to define list of tips available for manual selection later.Just take a look:And of course every enabled tip can be calibrated individually;)
How does the temperature sensor in 936 soldering stations work? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: December 18, 2018, 04:39:01 pm
content: I am seeing conflicting answers: someone claim it being a thermistor and some claim it being a thermocouple. What is it? And how do I find specs about it?This is for my soldering station project. I intend to use a MCU to implement digital control, but I need to know how the temperature sensor work so I can design the feedback circuitry: should it be a constant current source driving the thermistor and ADC sample it, or should it be one of those thermocouple ADC chips.

author: hlavac
author_rank: Frequent Contributor
timestamp: December 18, 2018, 04:53:40 pm
content: In real Hakko 936 it seems to be some sort of thermistor (it says it should have 43 - 58 Ohm resistance according to the manual).Not sure what the clones of 936 use...
How does the Venstar Add-a-wire work? - Page 1
Forum section: electronics / projects

author: rea5245
author_rank: Frequent Contributor
timestamp: February 08, 2017, 04:00:34 am
content: Hi,Modern wi-fi thermostats require constant 24V power. That means they need one more wire than old thermostats needed. The Venstar Add-a-wire and ecobee's Power Extender Kit somehow multiplex two of your existing thermostat wires (e.g. the ones that switch on your heat or fan) into one. That frees up one wire so that you can use it for constant power.(Amazon linkhttp://a.co/5J41Dzy; install video:)These devices have a box that installs inside your furnace and a smaller thing - they just call it a "diode Y" - in the thermostat that splits the multiplexed wire into two.Now, it's easy to multiplex two digital signals onto one wire, but these gadgets are multiplexing two 24VAC signals, and they're doing it with just a so-called "diode" on one end.Can that really be done with just a diode? What's the likely mechanism they're using?Thanks,Bob

author: Cupcakus
author_rank: Contributor
timestamp: February 08, 2017, 08:04:24 am
content: If the signals are AC they can be phase shifted and combined onto one wire at the HVAC, and then a diode phase detector circuit at the other end splits it again? Wild guess, this is outside my expertise.

author: mmagin
author_rank: Frequent Contributor
timestamp: February 08, 2017, 08:24:39 am
content: Huh, pretty clever gadget.Well, in these thermostat connections (before using this device), there is not significant information in the 24 VAC, it's just expressing a binary state by closing a contact and passing the voltage (0 or 24 VAC) from a common wire to another wire (e.g. request heat, request cool, etc). It looks like the main box is put at the end where the 24 volt transformer supply is (furnace, etc.). So for example in the attached image, by adding the diode Y, the "add a wire" box at the other end can detect whether it is seeing 0, positive pulses, negative pulses, or AC on the shared line, and then it can close relays on its 'output' side as appropriate. You could decode this on the receiving end in a number of ways, some even as simple as a couple more diodes and a couple capacitors. (You might add some active circuitry to reliably drive relay coils, perhaps)

author: rjparker
author_rank: Newbie
timestamp: December 05, 2018, 08:13:12 pm
content: One way...
How does the zvd circuit work - Page 1
Forum section: electronics / projects

author: cambazz
author_rank: Newbie
timestamp: October 16, 2017, 12:08:01 pm
content: Hello All,How does this "ideal diode" circuit work?How can I determine max current and max voltage tru it?Can I use it to feed motor drivers that cause noise in my mcu power bus? Or would there be a limitation?Best Regards,C.

author: Ian.M
author_rank: Super Contributor
timestamp: October 16, 2017, 12:57:33 pm
content: The dual transistor is configured as a comparator, sensing the voltage difference between its emitters. It will have a linear transition between low and high on [U14:4] over a small range centred on a point where V[U14:5] is fractionally lower than V[U14:6]. When V[U14:5]>>V[U14:6], [U14:4] is pulled up to near v[U14:1], turning the MOSFET off. When V[U14:5]<<V[U14:6], R3 pulls the MOSFET gate down, turning it on.Max current is set by the MOSFET's Id_max and dissipation due to I2R losses in its Rds_on, though if there is insufficient gate drive voltage, losses in its body diode may take over.Max voltage has four constraints - the ideal diode cathode voltage is limited by U14 Vcbo_max and Q3 Vgs_max, and the maximum reverse voltage across the diode is limited by U14 reverse Vbe breakdown and Q3 Vds_max. None may be exceeded.I would not expect it to do well at eliminating transient over-voltage on its supply when feeding motor drivers as it is unlikely to react to spikes fast enough to make a difference. It certainly wont stop the supply dipping and browning out the MCU during sudden acceleration of the motor.

author: timb
author_rank: Super Contributor
timestamp: October 16, 2017, 02:05:51 pm
content: If that’s the circuit I’m thinking of, it’s used on the Raspberry Pi. As Ian.M said, it most likely won’t work well to prevent back EMF from a motor causing transients on your supply rail.For that an ideal diode would be pointless anyway.
high pass - Page 1
Forum section: electronics / projects

author: bonyz
author_rank: Contributor
timestamp: August 05, 2023, 05:37:26 pm
content: .

author: bonyz
author_rank: Contributor
timestamp: August 06, 2023, 06:47:56 am
content: .

author: moffy
author_rank: Super Contributor
timestamp: August 06, 2023, 12:05:26 pm
content: I think I can answer 4 questions:1. The HV comes from the person in the form of static. That's why static mats and static handling precautions should be used in handling ics.2. The "HF rejection" would be to eliminate RF from say mobile phones etc.3. The instrument amp looks to have an integrator as feedback which normally means that the offset is compensated, normally looks like a high pass filter.4. The waveform looks similar to that used in blood pressure monitors, the heartbeat, but detected by pressure, the filtering both HP and LP is to help shape the pulses to be easily detectable.

author: bonyz
author_rank: Contributor
timestamp: August 06, 2023, 02:22:22 pm
content: .
How does this circuit work with comparators? - Page 1
Forum section: electronics / projects

author: WalterPz
author_rank: Newbie
timestamp: January 16, 2024, 03:39:29 pm
content: Hello,I've been reviewing the Power Profiler Kit II design and noticed that it features an automatic switching stage depending on the measurement scale. Could someone please help me understand how the automatic switching stage works? I'll share the two most relevant images, although you can download the complete design from this link:https://www.nordicsemi.com/Products/Development-hardware/Power-Profiler-Kit-2/Download#infotabs

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 18, 2024, 09:43:25 am
content: The 4 comparators compare a voltage proportional to the current (voltage across shunt(s), amplified) as you probably figured, and a threshold that depends on the output of the next comparator(s). What this is essentially forms is the equivalent of an analog FSM (finite state machine).Each comparator will enable a PMOS that switches a shunt in parallel with other shunts. The 1k shunt is always in the circuit, the other shunts are choosen to make decades.The exact thresholds for which each is activated, and the state transitions would require a bit of time to determine. At first sight, it looks like transitions can only happen from one comparator to the next, thus activating one or more shunts depending on the measured current, in sequence.The idea of course is to automatically select a shunt value that optimizes the measurement range for a given current range, allowing a much higher measurement dynamic than if there were only one shunt.To analyze the states further, keep in mind the comparators "activate" shunts via a PMOS, so when their output is a low level, so when the measured current is above a given threshold (as the current sense voltage goes to the '-' input of the comparators). In this circuit, judging from the label names, the low level is -2V, while the high level is +7V. Additionally, the comparators have some hysteresis (positive feedback) to avoid oscillating between states when the sense voltage is too close to a given threshold. Finally, there is some low-pass filtering to limit the rate at which the states change (thus, the value of the shunt.)Hope it helps. A detailed analysis of this "analog FSM" will require a bit of work.
how does this circuit works? - Page 1
Forum section: electronics / projects

author: Danesh_SA
author_rank: Contributor
timestamp: December 21, 2019, 08:11:41 am
content: Hi All,Im on a isolated digital output circuit,i found this circuit.could you expain me how it works? what does BAV70 do here?

author: erikka
author_rank: Regular Contributor
timestamp: December 21, 2019, 08:43:55 am
content: See equivalent circuit of each driverThe diodes are to clamp the output between GND and Vcc

author: Danesh_SA
author_rank: Contributor
timestamp: December 23, 2019, 03:10:06 pm
content: I design 4 channel digital output for industrial system ,I want to use ULN2803 instead of TBD62783 in my design.but don't understand the usage of BAV70 here,this is DIGITAL OUTPUT ,why in this design use CLAMP diodes?

author: awallin
author_rank: Frequent Contributor
timestamp: December 23, 2019, 03:19:12 pm
content: if you have inductive loads (relays) they might give enough 'kick' to damage the driver, without protecting diodes?

author: PKTKS
author_rank: Super Contributor
timestamp: December 23, 2019, 03:19:43 pm
content: Quote from: Danesh_SA on December 23, 2019, 03:10:06 pmESD or worst spikes

author: rstofer
author_rank: Super Contributor
timestamp: December 23, 2019, 03:38:44 pm
content: To prevent the signal lines from going above Vcc by more than a diode drop. This protects the chip inputs (or outputs, in this case). It doesn't matter WHY the signal line goes above VCC (ESD, whatever), it is necessary to protect the chip.Given that each output is also fused, we can assume it is intended to protect the device from miswiring. Inductive kickback is handled inside the driver chip for the case where the output goes below ground. These external diodes clamp when the output is somehow pulled above Vcc.

author: Danesh_SA
author_rank: Contributor
timestamp: December 23, 2019, 09:39:14 pm
content: Quote from: rstofer on December 23, 2019, 03:38:44 pmThank you for detail answer.now i find out how it works,but still can't understand how BAV70 works in output mode!I think it prevent damege to chip when we use it as INPUT ,which is wrong and these diodes to prevent from failing.I have this ideas but I don't know do I think in right way?!
How does this feedback network work? - Page 1
Forum section: electronics / projects

author: Red_Micro
author_rank: Regular Contributor
timestamp: February 28, 2020, 03:18:21 am
content: Hello,In the circuit below, what's the function of D18 and C37 at the junction of R24 and R27? Do R24 and R27 look like they are in series with R26?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 28, 2020, 07:47:14 am
content: VFB is the AUX winding, and I guess U1 is a quasi-resonant or BCM controller? Guessing they wanted to adjust the rising and falling timings slightly. Or maybe D18-R24-C37 serves as a snubber for D28 and the winding, and they're just taking feedback from there for whatever reason.Tim

author: Wimberleytech
author_rank: Super Contributor
timestamp: February 28, 2020, 05:38:19 pm
content: I don't get it. R24 appears to be a 205 ohm 1% resistor.

author: bson
author_rank: Unknown
timestamp: February 28, 2020, 05:51:20 pm
content: R24 and C37 will make the driver briefly overshoot during start and acceleration.D18 allows fast discharge of C37 when VFB drops, so it doesn't undershoot when slowing. Well, maybe a little due to the diode Vf.

author: Wimberleytech
author_rank: Super Contributor
timestamp: February 28, 2020, 05:53:48 pm
content: Quote from: bson on February 28, 2020, 05:51:20 pmIs there a reason for the 1% value for R24?

author: xavier60
author_rank: Super Contributor
timestamp: February 29, 2020, 12:24:09 am
content: Quote from: Red_Micro on February 28, 2020, 03:18:21 amThe IC does some really clever things with the CS pin.http://www.ti.com/lit/ds/symlink/ucc28711.pdfI still don't understand how it knows where to sample the correct part of the AUX waveform that represents secondary voltage. Anyways the reference is 4.05V which needs the top divider resistance to be close to 90K to get 16V AUX.So R24 is really the odd value of 205Ω, not possibly 2MΩ.Although the CS pin is supposed to reliably block the leakage inductance pulse, the designer of this PSU has decided to RC filter it.D18 is likely there to quickly discharge C37 during downward swings so that the valleys can be properly detected after demagnetisation.
How does this IC  work? - Page 1
Forum section: electronics / projects

author: fonograph
author_rank: Frequent Contributor
timestamp: November 23, 2018, 06:11:08 pm
content: Its supposed to be volume control,in datasheet I found word "resistor ladder",I also found word "amplifier",it have alot pins,wtf is this thing and how does it work?Is it amplifier? Is it some kind of volume control IC? Is it some weird active hybrid volume morphing op amp gizmo?Does it decrease volume by passive resistance like potentiometer or is this case of active circuit sorcery?https://www.google.sk/url?sa=t&source=web&rct=j&url=https://www.mouser.com/ds/2/294/NJW1195_E-69285.pdf&ved=2ahUKEwiT0L7RjuveAhWD6qQKHXHlCw8QFjAAegQIABAB&usg=AOvVaw2OVh08J254k-drNO6JOyzq&cshid=1542996774066

author: Benta
author_rank: Super Contributor
timestamp: November 23, 2018, 06:38:44 pm
content: It's a combination of analog switches and digital potentiometers (and associated control logic).

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 23, 2018, 06:53:50 pm
content: Yeah it is much like the PGA2320 except it has additional MUXes to handle 4 inputs.The volume control itself is basically a resistor ladder and a series of switches. You can get a basic idea with this:https://en.wikipedia.org/wiki/Logarithmic_resistor_ladder

author: fonograph
author_rank: Frequent Contributor
timestamp: November 23, 2018, 07:03:07 pm
content: Is this passive stepped attenuator with bunch of various matched resistors combined with digitaly controlled solid state relays? Is there some active amplifier in the signal path? Some op amp-ish ouput buffer or something like that...
[SOLVED] How does this Jack socket function? - Page 1
Forum section: electronics / projects

author: negativ3
author_rank: Regular Contributor
timestamp: October 30, 2017, 03:52:37 pm
content: Hi all, should maybe reside in the beginners section, but I'm curious as to how the jack socket below functions.No plug = 2-4 and 3-5 shorted?With plug = 2-4 and 3-5 open with 4 and 5 being signal paths following insertion?Or is this some sort of short circuit protection during plug insertion?I need a jack for my latest project and these smd ones look nice.

author: rstofer
author_rank: Super Contributor
timestamp: October 30, 2017, 03:58:36 pm
content: It seems to be a stereo microphone input. The inputs are on 2&3 while ground is probably on 4 & 5. Pin 1 is also probably ground.The idea is to short out the input to the amplifiers when there is no microphone connected.Physically, when the plug is inserted, contacts 2 & 3 move away from contacts 4 & 5.

author: ovnr
author_rank: Frequent Contributor
timestamp: October 30, 2017, 03:59:34 pm
content: This is a normal switched jack. Yes, the listed pins will be shorted.The purpose of these are for detecting whether anything is connected, or passing the signal elsewhere. Think of an old radio with a built-in speaker; when you plugged headphones into it, the speaker would cut out and the sound would appear only in the headphones. In that case, you'd apply the signal to pin 2 and 3, and connect the input of the speaker amp to 4 and 5.

author: perieanuo
author_rank: Frequent Contributor
timestamp: October 30, 2017, 05:22:15 pm
content: Quote from: ovnr on October 30, 2017, 03:59:34 pmOn laptops I saw that used to cut internal sound speakers when connecting external onesEnvoyé de mon HUAWEI NXT-L29 en utilisant Tapatalk

author: negativ3
author_rank: Regular Contributor
timestamp: October 30, 2017, 05:42:33 pm
content: Thanks a lot guys, explained perfectly ovnr.
How does this regulator work? - Page 1
Forum section: electronics / projects

author: james_s
author_rank: Super Contributor
timestamp: February 04, 2020, 06:53:21 pm
content: I recently pulled out this TDS460 power supply to take another crack at repairing it and I'm reminded of what a strange design it is and trying to wrap my head around just how this works. It consists of a primary side driving a single transformer at 32kHz which is open loop aside from over voltage shutdown. The secondary side has four very similar sections each with their own winding which are each regulated and adjusted individually without any feedback to the primary side.At first glance I thought they were simply shunt regulators which would be bizarre but I suppose it could work however I then realized it's just a small signal transistor and these outputs each deliver up to several amps. Then I thought maybe they are creating a DC bias to control saturation of the core, but then how could each output be adjusted individually without affecting the others? I have a couple of these power supplies and on one of them one of the outputs works correctly and adjusts over a range of about +/- 15% without affecting the rest.One clue is that inductor closest to the transformer is ahead of the rectifier so I wonder if there is some kind of clever resonant thing going on here. Or maybe they are controlling saturation of the inductor?

author: Vovk_Z
author_rank: Super Contributor
timestamp: February 04, 2020, 07:16:01 pm
content: It's a kind of magnetic amplifier.Look here for an answer.Something like:"Sending current through them in the other direction via L201 (L202) and diode CR209 reduces this net DC component through both coils, which increases their inductance and therefore their impedance, reducing the output voltage."ATX power suply 3.3V regulator is done that way usually too

author: james_s
author_rank: Super Contributor
timestamp: February 04, 2020, 07:25:15 pm
content: Ah ha! Things are starting to clear up a bit! Maybe now I can actually get these going, I had one with all outputs high, regulation not working at all and someone gave me another one which I finally made some progress and have it running with one output regulating. Trying to understand how the regulation worked has been really bugging me.
How does this sealing machine works? - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: June 13, 2017, 10:37:18 am
content: Hi,My friend send me this puppy for repair, I just wanted to know what's the principle behind it, I can see it has a full-bridge MOSFET that is tied to a mysterious big chunky inductor that's connected to this huge heat sink. which I think can do the welding with the magnetic field.any Ideas are welcome!

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: June 13, 2017, 11:02:04 am
content: The main controller part is SG3526 and the MOSFETs are APT55M50JFLL ,and two IR2113 MOSFET drivers, you can see the big self and caps there, I think they have used the litz wire for them! there is nothing special with this puppy, everything is jelly bean parts.

author: P90
author_rank: Frequent Contributor
timestamp: June 13, 2017, 11:06:38 am
content: looks like it's an inductive sealing unit. An inductive coil creating a varying magnetic field heats some sort of aluminium layer in the sealing material and melts it to the container.

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: June 13, 2017, 11:57:37 am
content: Thanks for the info, would you explain more? how is the SG3526 working? do you have any tutorial or app note about it

author: macona
author_rank: Regular Contributor
timestamp: June 14, 2017, 05:31:43 am
content: Yep, its an inductive sealing unit, it heats up the metal foil in the package which melts the plastic when it is squished in the sealing jaws.The SG3526 is a pretty generic PWM chip, it drives the gates of the mosfets in a H-bridge which turns the DC coming in to AC, basically a high frequency inverter. The rectangular blue caps are part of the tank circuit.

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: June 14, 2017, 12:03:46 pm
content: QuoteThanks Macona, Do you have a simplified circuit diagram? thanks in advance
How Does this Si53314-B-GM Clock buffer works? - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: December 15, 2020, 02:45:02 pm
content: Hi,I just wanted to know if I can get 12 LVCMOS clock outputs from a single clock with Si53314-B-GM or I would get 6 clocks and 6 complementary clock outputs,I want to make sure all the 12 LVCMOS clocks has the same polarity, some how the datasheet is a bit confusing.Any one in here has done project with these clock buffers?

author: djerickson
author_rank: Regular Contributor
timestamp: December 20, 2020, 01:58:53 pm
content: This part is differential output only. It outputs 6 signals, each with positive and negative polarity.Go fishDave

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: December 21, 2020, 09:08:55 am
content: Thanks, do you recommend any 12out put part?
How does touching USB shield induce voltage spikes into power supplies? - Page 1
Forum section: electronics / projects

author: Boscoe
author_rank: Frequent Contributor
timestamp: August 21, 2017, 11:48:36 am
content: I'm working on a battery powered device which is charged via a USB connector - the USB is not used for data communication. When the USB shield is touched with a USB cable connected to a PC or wall adaptor the power supply rails fall out of regulation (to zero) after a spike is seen (up to 20V). The power pin on the connector has not made contact at this point - just the shield.This was of a particular issue when the MCU debug point was connected to the device, earthing the GND on the PCB. The shield used to be directly connected to GND, too, so it was thought a large current would pass through the board when you made the earth loop causing a this voltage spike. However the failure would still happen when the debug was not connected and just on battery power.In a new revision, after some reading, it was decided to connect the shield to GND through a 1M resistor and 4.7nF capacitor in parallel. This did not help but removing the capacitor did (which makes a little sense) and so did removing the 1M. So we now have a very no ideal floating USB shield but the problem still persists. The shield is completely floating, the board is not connected to anything and just touching the USB shield to earth can cause the device to shutdown due to a power spike.The two power supplies are generated with DC-DC ICs from TI and Murata, the TPS61089 and LXDC2HL33A-055.How is this remotely possible? And what is the best way to solve it?

author: capt bullshot
author_rank: Super Contributor
timestamp: August 21, 2017, 12:52:29 pm
content: Your problem appears to be a missing or bad decoupling capacitors problem, or a missing or bad ground plane.Check all your ICs supply pins for proper grounding / decoupling. Check enable on DC/DC converter chips pins for correct termination, check reset input pins of digital ICs for correct termination (often a small capacitor to GND is required to suppress unwanted resets)

author: David Hess
author_rank: Super Contributor
timestamp: August 21, 2017, 03:03:09 pm
content: Quote from: Boscoe on August 21, 2017, 11:48:36 amI suspect two different problems; the ground that the shield was connected to did not have a low enough impedance to prevent coupling between the shield and signals and the signals themselves were not protected well enough against transients.The shield connection should go to a separate chassis ground separate from the signal ground which is pin 4.

author: Boscoe
author_rank: Frequent Contributor
timestamp: August 21, 2017, 03:12:54 pm
content: Thank for for the replies. The problem was the transients on the power supply rails were affecting a signal that powers off the entire board. A filter on this signal solved the issue.
How do wearable devices communicate with Android phones - Page 1
Forum section: electronics / projects

author: trevwhite
author_rank: Frequent Contributor
timestamp: April 08, 2016, 09:01:11 pm
content: Hi AllSomeone today showed me their android watch and then showed me on their phone how the watch tells the phone its battery life left. In the drag down status bar of the phone there is a line saying WATCH and the percentage of battery life left. I have a device that I want to do the same thing with and it would be great if I do not have to write an app but can tap into something already existing in the Android OSI am hoping that its some bluetooth connection and their is a standard api already in place to enable such a feature so that I do not have to write any custom application for Android phones.Anyone got any pointers?ThanksTrev

author: RGB255_0_0
author_rank: Frequent Contributor
timestamp: April 08, 2016, 09:03:49 pm
content: Starthere.

author: trevwhite
author_rank: Frequent Contributor
timestamp: April 08, 2016, 09:14:42 pm
content: Thanks for the link. My wearable device is just a simple unit with bluetooth. Do you know if there is a specific example of how to connect between such a simple device and an Android phone or does the wearable API rely on both devices running Android?

author: Jeroen3
author_rank: Super Contributor
timestamp: April 08, 2016, 09:25:02 pm
content: You cannot google your wearable together. But if you insist, github is usually a good place to start looking.https://github.com/googlesamples

author: trevwhite
author_rank: Frequent Contributor
timestamp: April 08, 2016, 09:36:24 pm
content: Quote from: Jeroen3 on April 08, 2016, 09:25:02 pmI think I have not explained things very well. My device is not Android based but a simple embedded processor wuth builtin Bluetooth. I was wondering if there is a way to generate a notification like a watch does but not from an android wearable device and without a custom app needing written

author: Nerull
author_rank: Frequent Contributor
timestamp: April 09, 2016, 02:16:53 am
content: Most wearables that don't run android have their own app. I'm guessing there isn't a built in generic wearable API.You might try looking at this app, which can push notifications to any bluetooth device that implements the AVRCP profile:https://play.google.com/store/apps/details?id=com.github.grimpy.botifier&hl=en

author: trevwhite
author_rank: Frequent Contributor
timestamp: April 09, 2016, 10:40:54 am
content: There must be an underlying protocol of how they communicate between each other. If I can did out that then maybe I can pretend to be an android wearable device and so piggy back on the builtin support

author: viperidae
author_rank: Frequent Contributor
timestamp: April 09, 2016, 10:58:36 am
content: If it uses Bluetooth low energy, start by googling BLE GATT
How exactly does the Microtan 65 video circuit work? - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: September 12, 2015, 07:22:52 pm
content: I've been looking for a simple-ish discrete logic video circuit, and this one seems like the closest thing to what I want. The problem is, I can only find the same broad description copy-pasted across several different sites, and my google game isn't strong enough to find an "idiot's guide" to such a thing. I have a schematic, but it's pretty poor and I'm finding it a little difficult to follow.Does anyone have a very detailed block diagram for this sort of display, or know of any recommended reading that would allow me to teach myself? It would probably be easier to use a 6845 (which looks like it does the same job only better), but bog-standard 74xx parts will probably be available brand-new for the rest of my life, and doing it that way might be more fun

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 12, 2015, 10:08:34 pm
content: Not sure what you're after, but Don Lancaster's TV Typewriter might be what I think you want?http://www.swtpc.com/mholley/RadioElectronics/TV_Typewriter.htm
How generate a pdf file for bottom layer in eagle CAD? - Page 1
Forum section: electronics / projects

author: Dhanushka
author_rank: Regular Contributor
timestamp: June 24, 2019, 05:39:57 pm
content: I have downloaded the attached Eagle files from internet and it is a variable power supply.I am very new to Eagle.So, Please anyone tell me how generate separate pdf files for bottom layer and top silk layer.It is better for me to upload the separate files.Thanks

author: rstofer
author_rank: Super Contributor
timestamp: June 24, 2019, 05:49:43 pm
content: I don't use Eagle so ignore everything that follows...Can't you PRINT a layer to a Color LaserJet or <whatever> If so, why can't you print to the Microsoft PDF Printer device? It's standard on Win 7 and Win 10.I have no idea how sheet size will work out.

author: oPossum
author_rank: Super Contributor
timestamp: June 24, 2019, 05:55:43 pm
content: View menu, Layer settings...File menu, Print, Print to PDF

author: Dhanushka
author_rank: Regular Contributor
timestamp: June 24, 2019, 05:59:43 pm
content: Dear rstofer and oPossum,Actually the problem is when I open this file on eagle, it will show every layers. So, I need to generate pdf files separately to print. Example: bottom layerThanks

author: Karel
author_rank: Super Contributor
timestamp: June 24, 2019, 06:43:06 pm
content: Menu -> View -> Layer settings. Switch on/off the layers as you wish. Hit the Apply button. Check the result. Close the Layer settings.Hit ctrl+p. The printdialog will appear. Instead of a printer, select PDF. Adjust the filename and path.Adjust other settings as you whish.Hit the OK button.

author: Dhanushka
author_rank: Regular Contributor
timestamp: June 25, 2019, 02:40:44 am
content: Dear Karel,It workedThank you very much.
How good are transformers at surge protection? - Page 1
Forum section: electronics / projects

author: skipjackrc4
author_rank: Regular Contributor
timestamp: April 13, 2013, 01:51:12 am
content: The recent thread on mains surge suppression got me thinking about transformer based power supplies. Obviously, in a switch mode supply, there must be surge suppression via MOV, discharge tubes, etc, as well as noise filtering through a common mode choke and X/Y caps. Are these necessary on a transformer based supply, or does the inductance of the transformer suppress noise and/or transients well enough by itself?

author: amspire
author_rank: Super Contributor
timestamp: April 13, 2013, 02:50:38 am
content: Transformers certainly help protect against surge protection to an extent, but good protection is still dependent on a well designed combination of measures.You still want MOVs to limit the peak voltage and to divert the major current away from the transformer. Perhaps some filter inductors+ capacitor before the transformer. Definitely a fuse.Transformer windings will have a breakdown voltage, and so you have to keep the peak voltage spike into a transformer below that limit. Otherwise one big surge and you need a new transformer. Since most transformers in products are custom built transformers, it is a really good idea to try and protect the transformer as much as possible. Replacing is usually either very expensive, or it may be the transformer is no longer available and the only fix is a custom made replacement or a re-winding of the original transformer as long as the core is not welded.Mains transformers attenuate high frequencies, and at high currents, they will saturate restricting the peak output voltage. However, what you always have to remember with transformers is that after the core is fully saturated, you still have a transformer - the core no longer boost the magnetic coupling, but it still transforms the energy, so very fast high current spikes on the primary can still get to the secondary.Transformers add an excellent degree of protection from surges, but they are not complete protection of the secondary circuit from surges.Richard

author: skipjackrc4
author_rank: Regular Contributor
timestamp: April 13, 2013, 02:55:11 am
content: Thanks amspire. That is exactly what I thought.

author: peter.mitchell
author_rank: Super Contributor
timestamp: April 13, 2013, 07:53:11 am
content: Quote from: amspire on April 13, 2013, 02:50:38 amThis is a pretty good piece of text, I think you should stick it in the wikipedia article for transformers.