hybridfree/eevblog-posts huggingface dataset:
Isolated Dual-output PSU design, sharing GND for multi-tapped transformer... - Page 1
Forum section: electronics / projects

author: STM32
author_rank: Newbie
timestamp: June 16, 2023, 02:22:40 am
content: The following design (attached pic) is a dual-output Flyback PS generated by PI expert. The transformer used is a custom multi-tapped transformer. The 3.3V is used to power the control MCU, while the other 5V rail is there for the high power load. As you can see in the design, the 3.3V is isolated from the 5V winding. GND is not shared like in center-tapped transformers.My question is, how I can share GND between these two domains? I have seen similar designs connecting the grounds via a 10 Ω resistor. I was wondering if I can do the same approach on this design.

author: dobsonr741
author_rank: Frequent Contributor
timestamp: June 16, 2023, 02:51:09 am
content: I do not see any issue connecting the two grounds together directly. Unless you have specific untold requirements....

author: ArdWar
author_rank: Frequent Contributor
timestamp: June 16, 2023, 03:01:33 am
content: FYI you probably want a stacked secondary winding instead of fully isolated if you don't strictly need isolation between the two outputs. An isolated design with single feedback may results in quite adventurous voltage excursions on the second output. Especially when the first (regulated) output is connected to dynamic high power load

author: STM32
author_rank: Newbie
timestamp: June 16, 2023, 03:52:28 am
content: QuoteOf course I don't, and if I do, I would be glad to elaborate more on that here!

author: STM32
author_rank: Newbie
timestamp: June 16, 2023, 04:10:15 am
content: QuoteYou're right, in fact, I was supposed to go that route from the beginning. A fully isolated secondary was not necessary for the target application, but I just realized that too late after ordering the transformer.@dobsonr741:So, connecting these grounds directly should be fine?
Isolated Gate Driver Recommendation - Page 1
Forum section: electronics / projects

author: willPowell
author_rank: Contributor
timestamp: February 08, 2022, 10:39:44 am
content: Previously I used isolated optocoupler solid state relays to switch on and off a system. They worked great but the frequency was not quite high enough.I am looking for an isolated gate drivers to drive 4 N channel Mosfets in H-Bridge configuration with the following requirements:Fast switching circuit (at least 20kHz)For a 30V power supply,Capable of powering a none inductive load of 10k. I.e. very low current required - 3mA max current.Controlled by a 3.3V microcontrollerAs simple component as possible, that just worksThanks in advance,Will

author: turboplayer777
author_rank: Newbie
timestamp: February 08, 2022, 03:34:06 pm
content: I successfully used the ADuM3223https://www.analog.com/media/en/technical-documentation/data-sheets/adum3223_4223.pdfin a H-Bridge. They are super simple to use and offer a good insulation. But they aren't cheap. Are you sure about these load requirements? If you're planning on driving MOSFETs, then you're going to get much higher currents than 3mA, at least for a short period. Also they can only handle a 20V max supply, but you can't drive most MOSFETs with 30V anyway. Or are you trying to supply something else directly, without MOSFETs?Regards

author: m98
author_rank: Frequent Contributor
timestamp: February 08, 2022, 10:18:49 pm
content: Which MOSFETs are you trying to drive? Did I understand it correctly that the resistive load of 10k is the one you're trying to drive with the H-Bridge?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 09, 2022, 04:43:32 am
content: Related thread:https://www.eevblog.com/forum/projects/full-bridge-gate-driver-doing-funny-buisness-(h-bridge-circuit)/Apparently it's actually a current source, not a 30V constant(ish?) voltage source. And apparently now also needs to be isolated.OP doesn't seem very forthcoming in details or application, at least as yet.Tim

author: Zero999
author_rank: Super Contributor
timestamp: February 09, 2022, 01:50:54 pm
content: Quote from: turboplayer777 on February 08, 2022, 03:34:06 pmI like the ADuM5230, which has a built-in high side power supply.https://www.analog.com/media/en/technical-documentation/data-sheets/ADuM5230.pdf
Isolated gate drivers for series MOSFET configurations in HV applications - Page 1
Forum section: electronics / projects

author: fracton
author_rank: Contributor
timestamp: September 21, 2024, 06:12:39 pm
content: I'm trying to build a high-voltage (HV) pulse generator for a Physics experiment based on a design that I found in a related textbook (see the attached image). This design uses pulse transformers to galvanically isolate the HV side from the gate drivers and optocouplers to further isolate the logic side. I am looking for isolated gate drivers with higher isolation voltages and those that can take TTL/CMOS trigger pulses as input from a pulse-width modulation (PWM) module to drive the MOSFETs.I am guessing this could improve this design by reducing the parasitic inductance and any resonances that can result from the RLC combination before the gate of the switch.Are there any gate drivers with 2-5kV Vrms isolation and can source and sink currents up to 4-6A per channel?

author: PCB.Wiz
author_rank: Super Contributor
timestamp: September 22, 2024, 12:00:40 am
content: Quote from: fracton on September 21, 2024, 06:12:39 pmDid you try Digikey and google ?very high voltage isolation is mostly about distance - so you want the widest package you can find.Examples easily found :https://docs.broadcom.com/doc/AV02-4249ENhttps://www.lcsc.com/datasheet/lcsc_datasheet_2011301808_Sillumin-SLM343CK-DG_C881768.pdfbut you may also want to think about the dV/dT rating, the SLM343 claims 150kV/us min vs Broadcom's 40kV min

author: Benta
author_rank: Super Contributor
timestamp: September 22, 2024, 12:10:41 am
content: I think you'll find out why gate transformers are used in this kind of application:They can supply the needed energy to the gates directly, and can be designed for almost any isolation distance you need.Optocoupler or level-shifter drivers need elaborate floating power supplies, which is super-difficult and complex in a circuit like this.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 22, 2024, 07:40:15 am
content: I'd also consider a common-source configuration with 0 and 180° power combiners.Tim
Isolated LED Driver > 60VDC ? - Page 1
Forum section: electronics / projects

author: AcHmed99
author_rank: Contributor
timestamp: January 06, 2014, 02:28:40 pm
content: I want to drive two LED's series connectedBXRC-30E1000-B-03. The maximum potential could go as high as 62VDC there will be OVP 67VDCmax. I would like to just use phase change material as thermal interface material. This provides no isolation between the heatsink and the case. What are the standards for safety for isolated 60VDC > for this sort of application?I can think of several ways to make it safe analog sensing of the current high and low-side, diiference amp then a comparator flip a PFET disconnecting the output like a solid state RCD. Make the return lead not easily accesible so it's impossible to complete the circuit with your body. I know they need double insulation when using non-isolated line powered drivers but what about isolated greater then 60VDC OUT?EDIT Scratch the RCD wouldn't work after some thought.

author: poorchava
author_rank: Super Contributor
timestamp: January 07, 2014, 12:14:10 pm
content: I don't know how about Canadian regulations, but in most EU countries safe DC levels are 120V in dry environments and 60V in humid and/or hot environments. For AC those levels are 50V and 25V respectively.Applicable protection mechanisms depend on what drive circuit you intend to use.

author: peter.mitchell
author_rank: Super Contributor
timestamp: January 07, 2014, 04:01:15 pm
content: Im pretty sure the rear of the package of those LEDs is isolated from the input/outputs. thus, it doesn't matter if the heatsink and case are electrically connected.
Isolated mains power - Page 1
Forum section: electronics / projects

author: Fixup
author_rank: Contributor
timestamp: March 03, 2016, 11:53:22 pm
content: Hi,I have many times needed isolated mains power for to make repairs safer. I found two identical transformers and decided to first transform down the voltage with the first transformer and then transform it back to mains with the other. In the same I added A DC power to the same box. The pictures below describe more

author: nctnico
author_rank: Super Contributor
timestamp: March 04, 2016, 12:24:09 am
content: OMGAnother one who thinks an isolation transformer will keep him alive. FFS: Get differential probes with proper CAT rating and use a ground fault interrupter in the mains connection!

author: rsee
author_rank: Contributor
timestamp: March 04, 2016, 09:27:55 am
content: I might just be tired, but why are you connecting your "isolated main" ground to the source ground? That would make it so they no longer have galvanic isolation. Also I agree need for the GFI.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 04, 2016, 10:06:14 am
content: Quote from: nctnico on March 04, 2016, 12:24:09 amCongratulations on being the only soldier in step in the whole parade.Isolation transformers have been used successfully for decades by knowledgeable techs whose employers cannot afford differential probes.Maybe a Noobmightcome to grief with one,but they will probably do so with a diff probe as well.

author: Fixup
author_rank: Contributor
timestamp: March 07, 2016, 10:29:29 pm
content: I agree about that the ground connection is NOT safe to have to the Isolated side. This socket was just added if I might find some use for it where I want the mains ground from primary side. In all cases when you are working with mains power you need to be careful. Since immediately when you hook up some USB cable or oscilloscope to the device under test it will have a return path and its "not nice" (Dangerous) to be the return path for the current.Isolation probes would be nice to have, aside with the isolation transformer.I have understood that you should only connect the device under test to the isolation transformer and NOT the oscilloscope.

author: RGB255_0_0
author_rank: Frequent Contributor
timestamp: March 07, 2016, 10:52:57 pm
content: Isolate yourself. Connect it to a fast acting RCD/GFCI. Only use one hand.Isolated or not, what saves your life is killing the power in a fault. Don't work around where metal work is ahs don't wear metal that could help electricity pass in or out.Again, isolation transformer doesn't mean it's safe and you have to be very careful about bonding the isolation earth back onto system earth as stated.
Isolated Switching DC Load - Page 1
Forum section: electronics / projects

author: dman66
author_rank: Newbie
timestamp: November 16, 2017, 10:22:45 pm
content: Does anyone have any suggestions for switching an isolated DC load other than using a mechanical relay?If it was AC (or periodic in some way) I'd use a solid state relay.The DC load is not very great (under 50v, low current).Right now I'm using an open collector output - but that is sharing a ground and causing other issues (connecting my board via USB to a PC makes a ground loop, etc.).Thanks!

author: viperidae
author_rank: Frequent Contributor
timestamp: November 17, 2017, 12:33:42 am
content: What about... a solid state relay?https://www.jaycar.co.nz/medias/sys_master/images/9001015738398/SY4086-dataSheetMain.pdfThat's 30VDC at up to 100A, I'm sure you can find something with a higher voltage if you need to. Or something smaller with a lower current capability.>4000V isolation

author: dman66
author_rank: Newbie
timestamp: November 17, 2017, 06:10:19 am
content: I should have also mentioned that the DC load doesn't have a fixed polarity.Most of the solid state relays I've seen that work with DC have a fixed polarity.

author: nidlaX
author_rank: Frequent Contributor
timestamp: November 17, 2017, 08:07:36 am
content: An H-Bridge??https://en.wikipedia.org/wiki/H_bridge

author: Jeroen3
author_rank: Super Contributor
timestamp: November 17, 2017, 09:34:51 am
content: Quote from: dman66 on November 17, 2017, 06:10:19 amMost solid state relays I've seen use two fets, and have no polairty. Search for AC,DC solid state relays.This one for example:CPC1916.

author: Zero999
author_rank: Super Contributor
timestamp: November 17, 2017, 11:38:53 am
content: Quote from: nidlaX on November 17, 2017, 08:07:36 amAn h-bridge will not do, since it's used for changing the polarity of the load, not switching an unknown polarity.What's the load current?

author: nidlaX
author_rank: Frequent Contributor
timestamp: November 17, 2017, 12:08:15 pm
content: Quote from: Hero999 on November 17, 2017, 11:38:53 amThanks.

author: David Hess
author_rank: Super Contributor
timestamp: November 20, 2017, 01:06:07 am
content: Solid state relays which use a pair of back-to-back power MOSFETs may be used in DC applications.

author: floobydust
author_rank: Super Contributor
timestamp: November 20, 2017, 03:15:21 am
content: Consider using a photo-voltaic optocoupler i.eVishay VOM1271to drive a couple MOSFETs. Basically you're making a bi-directional SSR, good for AC/DC.Crydommake DC SSR's but unidirectional (likeGN series) but they are pretty expensive. I'm not sure if they have a bi-directional DC offering.
Isolated USB Programmer - USBProg v8.4 - Page 1
Forum section: electronics / projects

author: TJ232
author_rank: Frequent Contributor
timestamp: May 03, 2017, 07:01:47 am
content: Based on my own firmware development and programming needs I have designed a while ago a a fully isolated USB to Serial adapter for communication and also programming devices while properly protecting your USB ports and devices. Lately, thu a number of iterations, I have done some hardware changes to it to make it more compact and also fully compatible with modern MCU's, like ESP8266, etc:Integrated hardware Autoreset function makes it suitable for direct programming ESP8266, ESP32 and other MCU's that require it.If you use Arduino IDE/Platformio/etc for example with ESP8266, you will love it, as it doesn't need to press anymore RST/Prog buttons for new sketch upload! The autoreset function takes care of that, putting automatically the ESP8266 module in the right boot mode.Original Article with description, schematics, and usage example :http://www.esp8266-projects.com/2017/05/esp8266-usb-programmer-usbprog.htmlHappy breadboarding,TJ.

author: mikerj
author_rank: Super Contributor
timestamp: May 03, 2017, 09:25:18 am
content: That's a neat design. Is this effectively a bit bashed interface, i.e. the host software controls the low level programming protocol? Also does the isolated side work over the usual voltage signal range 3.3v to 5v?

author: TJ232
author_rank: Frequent Contributor
timestamp: May 03, 2017, 10:31:51 am
content: Quote from: mikerj on May 03, 2017, 09:25:18 amThank you mikerj.I have used it industrial/harsh environments with 3.0, 3.3 and 5V targets on the isolation side without any problems.Actually the Silicon Labs digital isolator IC has a voltage range of 2.5 V < VDD < 5.5.It was not in the main target but it is also working nice with ESP8266 and Arduino stuff, direct programming, no more buttons to press or jumpers to set, smooth and fast programmingProgramming software is on Host side. Basically you can see it as a transparent USB-to-Serial interface and you can even use it like that (Rx and Tx target Pins) for safe isolated communication with your target device.When using as a programmer, if needed for your MCU (as ESP8266 needs for example), it brings the extra set/autoreset functions that will keeep you away from the hasle of setting jumpers and pressing buttons to go in the right BOOT mode for programming.You can see here afirmware upload exampledone on a Home Automation Dev Board with ESP8266:Also, as a comparation, the same process witha standard USB adapter
Isolation in battery operated medical devices - Page 1
Forum section: electronics / projects

author: poorchava
author_rank: Super Contributor
timestamp: September 10, 2013, 10:22:44 am
content: I got this job to design a medical device that is battery operated.I will surely have to go through IEC 60601 and other similar stuff, but before I do that I'd like to know what do the standards say about the insulation for battery-only operated equipment. For mains powered or mains charged stuff there are obviously requirements for isolation strength, maximum leakage currents, ESD and the like. What I'm supposed to design will be completly self contained, battery operated and non rechargeable (either one time use disposable, or factory refurbishable). Do I need to provide electrical isolation between power supply and sensing circuitry? So far I do not forsee using any voltages beyond +/-5V internally.

author: amyk
author_rank: Super Contributor
timestamp: September 10, 2013, 11:10:03 am
content: It depends what exactly you mean by "medical device". Something that is coupled with low resistance electrodes to the body (e.g. ECG) has the potential to be more hazardous under fault conditions than e.g. a glucose meter.

author: poorchava
author_rank: Super Contributor
timestamp: September 10, 2013, 11:37:07 am
content: Yes, the whole device is supposed to be worn by / attached to patient for several hours. The device will most likely use electrodes similar in construction to ones used in ECG and EEG monitors, so connected to an opamp.So there is an electrical path from inside the device to the patient, but it's a high impedance one and the max voltage on circuit side would be 5V in the worst case.
Isolation Transformer and Variac Safety - Page 1
Forum section: electronics / projects

author: Bryan
author_rank: Frequent Contributor
timestamp: January 02, 2016, 09:36:03 pm
content: Good video on some pitfalls of newer isolation transformers. Seems the newer types are geared for medical use, not repair use. This video explains it better than a few others I have seen.https://youtu.be/XBsQ3sZ45Fk

author: nctnico
author_rank: Super Contributor
timestamp: January 02, 2016, 11:03:26 pm
content: Test bench safety and isolation transformers don't go together so skip that video!

author: Ian.M
author_rank: Super Contributor
timestamp: January 03, 2016, 08:23:45 am
content: Lousy video.Takes 6 minutes of waffling to fail to explain why you don't want the isolated outlet to have any earth connection, then starts discussing the pitfalls of trying to 'float' a scope with it. At 8:30 he lights a bulb between mains Live and the scope probe ground clip, proving that he doesn't care enough for his own safety to have a RCD (ELCB) on his bench supply circuit. He then manages to float his scope at 11:45 using an old USA 2pin socket to 3 pin plug adapter with a flying ground wire going nowhere, and proceeds to make his whole scope live on a bench filled with other presumably earthed test equipment via the scope probe ground clip, while holding it.In any workplace I've been in, he'd be on administrative leave while the company safety officer reviews his persistent failure to follow safe working practices.
Isolation transformer for capacitor dropped rectified 230VAC - Page 1
Forum section: electronics / projects

author: okw
author_rank: Frequent Contributor
timestamp: November 07, 2024, 11:48:45 am
content: I've been looking at these dangerous 230V to (e.g.) 5V circuits consisting of a bridge rectifier and capacitor dropper.They work OK with known and steady loads (like fans, LEDs, etc), where the user is cut-off any handling. A better way is of course to have a transformer to drop the voltage considerably before the bridge rectifier, but they're expensive and heavy, so I get why they rather use a cheap capacitor dropper.How much safer would it make this circuit using a 1:1 isolation transformer after the dropper?(Users would still be cut off handling the circuit.)It's for running an MCU to control a TRIAC and a relay.

author: Andy Chee
author_rank: Super Contributor
timestamp: November 07, 2024, 12:03:16 pm
content: If you're going to use a transformer in your design, then you don't need the capacitor dropper at all!Just use a normal low voltage transformer, bridge rectifier & regulator to power the MCU!

author: okw
author_rank: Frequent Contributor
timestamp: November 07, 2024, 12:12:56 pm
content: No, a 1:1 isolation transformer (230VAC in => 230VAC out).

author: Andy Chee
author_rank: Super Contributor
timestamp: November 07, 2024, 12:16:24 pm
content: I understand thatI'm saying that compared with a 1:1 isolation transformer, it's cheaper and less heavier to use a low voltage transformer to power the MCU, and delete the capacitor dropper.

author: squadchannel
author_rank: Frequent Contributor
timestamp: November 07, 2024, 12:33:59 pm
content: isolation transformers and regular transformers do not cost much different.do not use capacitor droppers. want to make a low-cost product?Design it with a 230V:9V transformer and a 7805.

author: Andy Chee
author_rank: Super Contributor
timestamp: November 07, 2024, 12:39:08 pm
content: This schematic snippet shows you how to isolate your MCU by using a small transformer and optocoupled triac driver.

author: m k
author_rank: Super Contributor
timestamp: November 07, 2024, 12:55:43 pm
content: Quote from: okw on November 07, 2024, 11:48:45 amHow much is heavy?
Isolation transformer for SMPS spike protection? - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: February 03, 2020, 05:15:43 am
content: Had several field failures of a ~200 watt SMPS in the same location and want to try something different. Leaving aside MOVs and GDTs etc, how well would an iron cored double-wound isolation transformer function to reduce mains borne transients? Could the iron be expected to saturate above a certain level and clip, or at least round off a spike? Maybe soften it enough so that the existing MOVs etc inside the SMPS could have a better chance of saving the day? Maybe even the added impedance of the transformer's leakage reactance might help? Any ideas regarding this approach? We need to get something that is ready to wire in, not construct from scratch because of safety certifications and legal liabilities. Was considering the following:https://au.element14.com/block/tim500/transformer-isolating-500va/dp/1131600?ost=1131600&ddkey=https%3Aen-AU%2FElement14_Australia%2Fsearch

author: Berni
author_rank: Super Contributor
timestamp: February 03, 2020, 06:34:53 am
content: Yep 1:1 transformers are one of the best ways of protecting mains powered electronics.They are usually designed to be pretty close to saturation at the rated voltage (copper is expensive) so in a overvoltage condition they indeed start clipping the waveform.Still its not a magic pill. If some resistance + MOV doesn't fix it there could be a different problem related to common mode voltage surges. Long wires can have a lot of inductance and so sharp transients can cause all 3 wires of the mains line jump together. This won't cause a MOV to clip because the differential voltage between the wires is still ok. For isolated devices (Like a FM radio) this is not really a problem since the whole device just rides along and keeps seeing the correct differential voltage across the live and neutral. But this can become a problem when the device is connected to other things (Like a TV connected to the coax cable network). Whatever else is connected to it might not want to follow along the common mode wave, when grounds are connected there could be excessive currents flowing between the two. When the grounds are not connected a excessive common mode voltage difference might develop between the input and output of the switching PSU, eventually becoming large enough to arc over the PSU transformers insulation or the internal EMI capacitors.In any way a isolation transformer should help but you should also take a look at the whole system as it could be as simple as adding a thick wire between two earthing points.

author: Circlotron
author_rank: Super Contributor
timestamp: February 03, 2020, 06:48:36 am
content: Okay, I'll try the isolation tranny and ground the centre of the secondary winding. That should take care of any common mode noise. Maybe also put somewhat more than the usual amount of X capacitor across the secondary too. 500VA transformer is hardly working so it should tolerate a bit of reactive power just fine.
Isolation X-fmr video - Page 1
Forum section: electronics / projects

author: JohnS_AZ
author_rank: Frequent Contributor
timestamp: May 01, 2011, 07:18:04 pm
content: Here's a good video on isolation transformers for a tech bench. Includes tear down and modding the unit to float the grounds. The guy lives fairly close to me but we've not met. He does, however, have a Dave Jones official T-Shirt. :-)

author: Zero999
author_rank: Super Contributor
timestamp: May 01, 2011, 08:38:41 pm
content: I think it gives all the information but is a little slow going.Funny, here in the UK medical isolation transformers don't have the secondary bonded to earth and are used to reduce leakage currents in equipment containing SMPSes. They also provide similar protection to RCDs in high reliability applications where a power cut could endanger life or result in data loss. An insulation monitoring circuit is used to give a warning if there's a short from the secondary to earth.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 01, 2011, 11:07:44 pm
content: well, i dont click the play button, my net is slowing here. but i got loads of isolated x-fmr here.

author: Zero999
author_rank: Super Contributor
timestamp: May 02, 2011, 08:49:21 am
content: Just another thought, it's a good idea to get an isolation transformer with two 120V secondaries and box it yourself, along with a DPDT switch wired to connect them in series or parallel giving 120V or 240V for testing EU/US appliances and universal SMPSes.http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=3618115I have a small (100VA) 230V isolation transformer which I use with a Variac to give a variable voltage.

author: EEVblog
author_rank: Unknown
timestamp: May 02, 2011, 01:08:25 pm
content: Quote from: Hero999 on May 01, 2011, 08:38:41 pmHey, nobody out does me for slow going videos!, this means war!Look out for my 4 hour ohms law video, coming soon!It's good to see Todd and others getting into videos.Dave.

author: mobbarley
author_rank: Regular Contributor
timestamp: May 02, 2011, 03:32:40 pm
content: good vid with good demonstrations - I wouldn't have been game enough to light a lightbulb through the shield of my osc probe though - but I only have two probes so I might be overprotective I guess
ispLEVER "Your licence has expired" - Page 1
Forum section: electronics / projects

author: NivagSwerdna
author_rank: Super Contributor
timestamp: June 01, 2021, 02:34:45 pm
content: I used ispLEVER last year (or maybe it was the year before) for a rather legacy 16V8 project using ABEL and it worked really well..... but now returning to the project I get "Your license has expired" Feature: LSC_CLASSICI thought ispLEVER was free?

author: oPossum
author_rank: Super Contributor
timestamp: June 01, 2021, 03:19:30 pm
content: It was a free 1 year license. It is now $590.79 for a 1 year license.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: June 01, 2021, 08:40:05 pm
content: Quote from: oPossum on June 01, 2021, 03:19:30 pmOuch!
Issue on charging current while switching two power sources - Page 1
Forum section: electronics / projects

author: Sourav123
author_rank: Newbie
timestamp: June 01, 2019, 01:49:35 pm
content: The circuit is to switch the voltage for battery charging circuit and not allow the solar power to 'other load' circuitry.The charge current is set to 1A where in this configuration it draws only 125mA. The diodes D1, D2, D3 are SS34A.When removed D2 and applied supply voltage to solar source it works fine.When I replace all the diodes to 1N4004, the circuit draw sufficient charge current.As I have tried this simulation using SS34A and 1N4004, I get no issues but practically for which property of SS34A I'm getting the problem.
Issue usign Vishay SiP32401A for unidirectional power flow - Page 1
Forum section: electronics / projects

author: satyanraj
author_rank: Newbie
timestamp: November 16, 2016, 05:13:14 am
content: Hi All,We area facing technical issue with a load switch used in our designWe are using Vishay SiP32401A load switch IC.You can download the Schematics from the following link : Refer Power Supply page.http://docs.toradex.com/103044-aster-carrier-board-schematics.zipThe function is to load switch IC is to restrict the flow of power from output side to input side.Configuration:- Vin pin of the load switch IC is connected to Micro USB power pin (+5V).- Enable of the load switch IC is connected to Vin pin of the IC.- Vout pin of the load switch IC is connected to the power supply input of the carrier board (+5V).Use case:1) +5V power DC power supply connected to input power connector of the carrier board.Micro USB cable is not connected.>> Load switch IC is in switched OFF state. This is acceptable.2) +5V power DC power supply connected to the input power connector of the carrier board and Micro USB cable connected (+5V on Vin pin of the IC).>> Load switch IC is in switched ON state. This is acceptable.3) +5V power DC power supply connected to input power connector of the carrier board and Micro USB cable is disconnected (after being connected before).>> Load switch IC is in switched ON state. This was not expected, as device offers reverse blocking. We expected that the load switch IC should switch OFF, when micro USB connector is disconnected.Any idea, what could be the issue?Thanks and Regards,Satyan
Issue with a reapaired Xiaomi S50 Vacuum Robot Accu with an ABLIC S-8254AA - Page 1
Forum section: electronics / projects

author: Vacainer
author_rank: Newbie
timestamp: March 04, 2023, 01:05:16 pm
content: Hey there.I have my Xiaomi vacuum cleaner robot now for several years and unfortunately a few months ago my original battery gave up. The robot always stopped suddenly while vacuuming and had a kind of sudden-death. I could then drag him back to the station and charge again but that's not the point to deal with itSo I have the old 18650 batteries carefully removed and tested with my SkyRC charger. Since 2 were already pretty much broken, I suspect that were the culprit.I ordered a replica battery in the higher price range with good ratings to also get a good replica PCB / BMS.Unfortunately, this weakened. I read on the Internet that the replica probably make more frequent times problems.Since the idea came to me I ordered at nkon.nl new 18650 batteries with the same cell chemistry, but more mAh. They arrived and have had after a mAh test with the SKyRC charger also very good values.So I have taken the original akku PCB and the new batteries and with a new spot-welder I got a pretty new accu for my S50 vacuum. With the result I am very satisfied. Of course I have the 8 previously balanced. All on 3,65V.Unfortunately, the selfmade-battery pack does not want to be charged in the robot (Xioami Roborock S50).I read herehttps://www.eevblog.com/forum/projects/issue-with-4s-bms-ablic-s-8254aa-and-aod403-mosfet/msg3298914something about aresetthat you have to do with the ABLIC S-8254AA BMS probably?Could someone help me and tell me which pins are exactly or how I can determine this. I have a multimeter there.

author: Vacainer
author_rank: Newbie
timestamp: March 04, 2023, 01:20:25 pm
content: Here some PCB pics.
Issue with constant current source for LED  - Page 1
Forum section: electronics / projects

author: Aluz
author_rank: Newbie
timestamp: June 07, 2023, 10:58:33 pm
content: I've been trying to build a constant current led control circuit, but I'm not sure why it's not working. I'm using the arduino output to control I_SP. Output voltage for LED is extremely low for some reason. Should be around 7-8v but for 12v supply is around 2-3v.Any help would be much appreciated.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: June 08, 2023, 12:04:45 am
content: It's more common to put the LED in the FET Drain, as that gives lowest voltage loss.As you have it now, the VGS of the fet subtracts from the VCC range.Moving the LED eliminates that Vgs dependance.

author: Aluz
author_rank: Newbie
timestamp: June 08, 2023, 12:08:07 am
content: Oh I see, should the wire between R3 and Imeasure exist?

author: PCB.Wiz
author_rank: Super Contributor
timestamp: June 08, 2023, 12:41:22 am
content: Quote from: Aluz on June 08, 2023, 12:08:07 amYes, that's needed for feedback.You move the UV LED up on the SCH to connect the + to VCC and - to MOSFET Drain

author: magic
author_rank: Super Contributor
timestamp: June 08, 2023, 04:46:24 pm
content: Measure voltages at all inputs and output of U1 and Q1 and see what isn't behaving the way it should.If you have a scope, check if there is no oscillation.Not sure what's the point of R3? Maybe you copied this schematic from somewhere and R3 was meant to go to U1 IN- rather than VCC?

author: DavidAlfa
author_rank: Super Contributor
timestamp: June 08, 2023, 08:02:53 pm
content: Don't use a N-Fet like that.The gate threshold is usually around 2.5-3V, that voltage Will be dropped bt the fet.Then the led drops another 2-3 volts, so 5Vcc won't work.Place the led at the drain!Also lower power loses by replace the sensing resistor with 1ohm, and dividing the output of the RC filter by 10.

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 08, 2023, 08:40:21 pm
content: Yes to the above.Use a current sink topology with a NMOS (source to GND) rather than a current source one.If you insist on a current source topology for some reason (which doesn't seem justified here), in the same context, use a PMOS instead (the current will in this case be proportional to the difference between VCC and the input voltage).

author: Zero999
author_rank: Super Contributor
timestamp: June 08, 2023, 09:07:04 pm
content: Put the LED in the drain.

author: Aluz
author_rank: Newbie
timestamp: June 09, 2023, 09:18:13 pm
content: Ok awesome, I will test this out. Thank you.
Issue with FT230x Chip - Page 1
Forum section: electronics / projects

author: obsolete
author_rank: Newbie
timestamp: October 25, 2017, 09:49:13 pm
content: Hello EEVblog! I have a question about a current project I am working on. I have designed my first pcb based on the attached schematic, and after ordering and assembling the boards, testing is not going as planned.... First a quick rundown of the schematic.I am using a FT230x chip in conjunction with the max203 rs232 transceiver in order for serial data from a separate PCB can be read by a tablet application.The issue: When plugged in the tablet recognizes that a USB device has been plugged in but there seems to be no data being sent from the tf230x chip to the max203 transceiver. The RXD and TXD lines have no data and are defaulted to 5v and 3.3 v respectively.I am not sure why this is, but I have a few culprits, with one being that I am not using the RTS and CTS pins of the ft230x chip, and the datasheet seems to not go into much detail about the implications of leaving them floating would be. I also did not include 10k pullup resistors to vccio on the RXD and TXD lines which could be causing an issue as well. There seems to be no other issues in terms of unconnected power traces and the internal charge pump of the max203 chip seems to work as well. Maybe these arent the issues at all and I should try a redesign of the schematic and board entirely. I would just like someone more knowledgable than I am to help, thank you!

author: Helix70
author_rank: Unknown
timestamp: October 28, 2017, 11:33:08 am
content: V+ on the MAX chip?Ground pin from the USB connector to the FT230?

author: H.O
author_rank: Frequent Contributor
timestamp: October 28, 2017, 11:50:01 am
content: V+ (pin8) on the MAX203 is the internally generated +10V however Vcc is on pin 7 and GND on 6 & 9, neither of which are shown in the schematic. Are they connected across the 5V rail and decoupled properly on your PCB?Also, make sure it IS a MAX203 you have. That's the one with built in capacitors, most others need external caps for the chargepump circuitry.

author: HowardNamath
author_rank: Newbie
timestamp: October 28, 2017, 05:17:14 pm
content: How are you sending data from the tablet to this board? Do you have a terminal application you're using to send characters to the virtual COM port?
issue with my Rigol 1054z ground? - Page 1
Forum section: electronics / projects

author: mluna
author_rank: Newbie
timestamp: July 13, 2021, 04:35:24 pm
content: Whenever I plug and turn on the oscilloscope I can measure 0.5 volts in low impedance mode;and around 50 volts (with floating ground), and 20 volts (with connected ground) in high impedance mode between the ground pin and the neutral pin, and between ground pin and phase pin in the power plug with a fluke 117.No probes connected.Is that normal?
Issue with S-8200 Battery Protection IC: Load Cut Disables DO/CO - Page 1
Forum section: electronics / projects

author: MaximilianMM
author_rank: Contributor
timestamp: August 03, 2023, 09:13:53 am
content: Hello fellow electronic enthusiasts,I hope you are all doing well. I am currently working on a project that involves using the S-8200 Battery Protection IC.Whenever I cut the load via SW3, the Battery Protection IC disables itself, turning DO (Discharge Output) or CO (Charge Output) off. Only after applying a charging voltage, the IC works again.Cutting the load should be a normal event for such an IC, right? Why does it trigger the protection? Has anybody some input on this?Thank you all in advance

author: ElectronicsHobbyist
author_rank: Contributor
timestamp: August 29, 2023, 11:09:18 pm
content: According to its datasheethttps://www.nkkswitches.com/pdf/SS3surfaceMount-1.pdfyour power switch is a so called "shorting" type meaning that when changing from V_BAT_PROT to GND if connects them together for a brief moment. This would explain the overcurrent detection tripping. I would suggest removing the GND from the switch because the TPS7A0233 disables its output if the EN pin is left floating.
Issue with the RX8025 RTC, any pointers welcome! - Page 1
Forum section: electronics / projects

author: Boscoe
author_rank: Frequent Contributor
timestamp: December 18, 2019, 01:33:14 pm
content: Hi all,https://support.epson.biz/td/api/doc_check.php?dl=app_RX-8025SA&lang=enI'm currently working with the EPSON RX8025 RTC (datasheet above) but I can't set he value in control register 1. There are 16 registers in the device all accessed by I2C, only register 0x0D is reserved. I can read and write the time, control register 2 and all the others but not control register 1! I have read through the whole datasheet and some example code to look for something like a lock but can't find anything other than the strange addressing. I've checked the logic analyser but it's all good. I find this most peculiar.If anyone has any advice or pointers it would be much appreciated.ThanksBoscoe

author: Boscoe
author_rank: Frequent Contributor
timestamp: December 18, 2019, 02:54:47 pm
content: I have tried two different PCBs and replaced the RTC on both.

author: Boscoe
author_rank: Frequent Contributor
timestamp: December 18, 2019, 03:09:03 pm
content: Okay, I have solved it. I was setting the calibration after the control registers which are reset after a calibration.
Issue with the TCA6416A - Page 1
Forum section: electronics / projects

author: Hexum064
author_rank: Contributor
timestamp: April 26, 2023, 07:56:41 pm
content: I know it might be a long shot posting this here but here it goes:I am testing out a TCA6416Ahttps://www.ti.com/lit/ds/symlink/tca6416a.pdf?HQS=dis-mous-null-mousermode-dsf-pf-null-wwe&ts=1682231416987&ref_url=https%253A%252F%252Fwww.mouser.com%252F.It's a real simple setup for now. All pins configured as inputs on both ports. All pins pulled high with 10K resistors.The problem I am having is, when I pull P00 (that's pin 0 for port 0) low, I can no longer communicate with the chip. As soon as I send the address over I2C, I get back a NAK. This only happens on P00 and has happened on two separate chips.Maybe I got a batch with a flaw in the silicon but I wanted to see if anyone else could see why this might be happening or has experienced anything similar. I am also totally willing to accept I missed something while reading the datasheet or that I am just doing something dumb. In any case, I would love to figure out why I am seeing this behavior.I attached a pic of the schematic

author: Andy Watson
author_rank: Super Contributor
timestamp: April 26, 2023, 09:24:10 pm
content: What have you connected to the Reset and Int pins?

author: Hexum064
author_rank: Contributor
timestamp: April 26, 2023, 09:26:52 pm
content: I haven't attached them to anything. They are floating.OMG. Do you think the reset is being just slightly pulled low being floating but in close approximation to P00?

author: Hexum064
author_rank: Contributor
timestamp: April 26, 2023, 09:28:53 pm
content: Wow. Just Wow.I thought I read that the reset was internally pulled high but I couldn't find that again. So I pulled it high with a 10k and the issue with P00 went away...

author: Andy Watson
author_rank: Super Contributor
timestamp: April 26, 2023, 09:30:07 pm
content: Datasheet says pulled-up to Vcc1 or Vccp through a resistor. - Table 5.1Actually, I'm not sure the Int needs pulling up, but the Reset definitely does.
Issues beading a thermistor? - Page 1
Forum section: electronics / projects

author: Pack34
author_rank: Frequent Contributor
timestamp: January 15, 2017, 03:32:18 pm
content: I have a thermistor that's on a sub-assembly that I'm reading using an INA330 thermistor amplifier. What the amplifier does, is it puts a current through the thermistor and a separate sense resistor. It then compares the two currents and outputs a voltage to be used by a PID controller.Now, I'm getting some noise in the thermistor at a frequency that's seen in a clock that goes down the same ribbon cable. My main concern are any inductive qualities since the current through the thermistor is what's used as the driving factor for the PID.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 15, 2017, 04:19:58 pm
content: You don't have an EMI filter on the thermistor input pin?Also, you're running clocks down unshielded cables?Tim

author: Pack34
author_rank: Frequent Contributor
timestamp: January 15, 2017, 09:00:34 pm
content: At this point, no. In the past this did not seem to be an issue but it's suddenly come up. I'm planning on putting on a ferrite bead to target the 50-MHz noise.On my To-Do list is to move from the ribbon cable to a flat flex to help mitigate noise.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 15, 2017, 09:21:54 pm
content: Geez man, at least add an RC, to filter outside crap, as standard practice!Tim

author: calexanian
author_rank: Super Contributor
timestamp: January 16, 2017, 10:12:30 pm
content: Quote from: T3sl4co1l on January 15, 2017, 09:21:54 pm+1 for adding a little RC filter. at that high of a frequency and what i am assuming to be a standard 10K or so thermistor a couple pf across the line would probably do the job.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 17, 2017, 08:50:40 am
content: Quote from: calexanian on January 16, 2017, 10:12:30 pmMore than that -- remember you're working against the impedance of the cable, not the thermistor. (The thermistor is all but irrelevant at 50MHz!) The rule of using only what bandwidth you need, would suggest that 0.1uF would still be "small" for the application -- but more than good enough for RF purposes!Tim

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 17, 2017, 06:44:52 pm
content: How fast is the thermistor? I'd think that even with a small one you could use pretty heavy filtration before affecting the response speed.
Issues Controlling BBC M17H DC pancake motor with Parker 512C - Page 1
Forum section: electronics / projects

author: slawekgonet
author_rank: Newbie
timestamp: March 03, 2024, 10:11:02 am
content: Hey,I'm attempting to driver BBC M17H DC axial flow servo motor with Parker/Eurother 512C speed controller and I am facing some issues.I've set the controller up with autotransformer to supply it with 230VAC as AUX and 90VAC MAINS (motor is rated for 105VDC nominal).Unfortunately, motor is running extremely choppy and in interrupted fashion - and is not able to spin at low RPM at all.https://youtube.com/shorts/lxh0J69C-WI?feature=shareDo you have any ideas what can be wrong? How to even start debugging this issue?Thanks!
Issues reading an AM27S29 PROM - Page 1
Forum section: electronics / projects

author: dexters_lab
author_rank: Unknown
timestamp: June 08, 2019, 01:00:19 pm
content: I've been needing to read out some vintage PROMs for a project to emulate a quantel paintbox within MAMEi have a TL866 programmer but it doesn't directly support many of these old PROMs so i have been making up adaptors to convert the pinout to something basic like a AM2716 which is supported, i then edit the results in a hex editor to account for differences in length etc as all these devices are all smaller than the 2716, this has worked really well on several other devices (27S19, 63S441, 27S33, 28L22) but i am having issues reading a AM27S29, every time i read it i get a different output.I have checked and rechecked my wiring and can't see any errors, shorts or bad connections etcDoes the collective have any suggestions as to what's going wrong?

author: coromonadalix
author_rank: Super Contributor
timestamp: June 08, 2019, 02:16:55 pm
content: maybe you should ask in the tl866 thread here :https://www.eevblog.com/forum/blog/eevblog-411-minipro-tl866-universal-programmer-review/1600/

author: chick0n
author_rank: Regular Contributor
timestamp: June 14, 2020, 09:00:15 pm
content: Hisorry for digging out this old thread.But i would like to read out an AM27LS19PC PROM (Low Power version of 27S19).Could you post a schematic of the Adapter? And explain how to edit the results?Thanks.
Issues regarding ATM90E26 energy metering IC - Page 1
Forum section: electronics / projects

author: Tenzin
author_rank: Newbie
timestamp: May 20, 2019, 09:58:58 am
content: I've been facing strange issue regarding ATM90E26 energy metering IC. I have done all the calculations and my schematics are also fine. The IC shows AC current, AC voltage, power and energy. At first the reading shows exact values on a resistive load but after few hours the when the respective registers are read the ac current register shows correct value but the voltage register show wrong value(the load as well as the input voltage is not changed). I checked the voltage and current using a multi meter. The current value matches but the voltage value doesn't match the reading showed by the multimeter. I compared the reading with other energy meters too.Any Ideas???
Issues regarding TPS63070RNMR buck-boost converter - Page 1
Forum section: electronics / projects

author: Tenzin
author_rank: Newbie
timestamp: April 08, 2018, 09:48:25 am
content: The IC doesnot work as specified in the datasheet. I even followed the design mentioned in the datasheet.Issues:In buck mode when the input voltage exceeds 11.5V the IC heats up rapidly and blows out even at no load, but the according to the datasheet the (Vin : 2-16V /Max input:18V /absolute Max:20V)In boost mode the output could not even provide 1A of current with input current of 4A. But the datasheet mentions minimum of 3A of input current and max of 4A.My design requirements where Vin(min):3V Vin(max):16V Iin(min):3A Iout(min):2ABut the datasheet mentions Iout of upto 2A.I have attached the link below:http://www.ti.com/lit/ds/symlink/tps63070.pdfAnyone have any solutions???I would be happy to know it.

author: Niklas
author_rank: Frequent Contributor
timestamp: April 08, 2018, 10:35:27 am
content: Can you provide more details of your setup? Inductor, capacitors and possibly the PCB layout in the relevant area. Remember that the inductor must be rated for the current and also be able to store the energy.