hybridfree/eevblog-posts huggingface dataset:
BMS Protection For Cordless Drill - Diode and Capacitor - Page 1
Forum section: electronics / projects

author: J_C
author_rank: Contributor
timestamp: July 01, 2024, 04:36:24 am
content: I've rebuilt a battery for a 14.4V Dewalt cordless drill, DW991. It has a brushed DC motor, probably about 250W, variable speed (same old biased transistor trigger module), and reversible. Battery originally NiCd, now Li-Ion.I've put a BMS in the battery pack and the datasheet (which lacks a schematic of the BMS itself) states:https://www.mantech.co.za/datasheets/products/BMS-40A-4S_SGT.pdfQuoteI don't happen to have any non-polar caps with a uF rating that high. Can I just put a couple 100uF polarized connected back to back across the supply leads at the motor? Since they start the suggested range of capacitance at 10uF, would two 20uF polarized back to back, be sufficient or is higher capacitance going to matter in this application?The datasheet makes no mention of a flyback diode but would that be a good idea as well, between the battery and speed controller (across the supply lines, not in series) since it's a reversible drill, or do you think that is already built into the speed controller or that it effectively negates the need for a flyback diode? If adding a diode would be beneficial, can it be something like a 1N4001 or do I need a fast recovery or schottky, or higher current rated than 1A?The BMS PCB already has a diode across the output as seen on the top right of the picture below, so would adding another just be redundant and no point in doing it? I've attached a picture of it and a "possible" schematic of the BMS but I have not reverse engineered it to know for certain that this schematic is correct, though it does not have the diode as pictured on the PCB, which is a bit odd as it came from the following site which claims it is "complete":https://circuitdigest.com/electronic-circuits/lithium-ion-battery-management-and-protection-module-bms-teardown-schematics-parts-list-and-working

author: elektryk
author_rank: Regular Contributor
timestamp: July 01, 2024, 05:10:59 am
content: There's probably a diode already built into the switch.

author: J_C
author_rank: Contributor
timestamp: July 03, 2024, 06:33:44 pm
content: Yes I can check for that, but nobody has any thoughts about the protection cap the datasheet mentioned?I'd watched a few youtube videos of people converting cordless tool batteries but don't recall anyone adding that cap, and while I haven't torn apart alotof Li-Ion powered tools and batteries, don't recall seeing that type of cap on them from the factory either, at most just some little, maybe 0.1uF ceramic on the motor terminals for electrical noise reduction.
Struggling to find a simple BMS Solution - Page 1
Forum section: electronics / projects

author: Boscoe
author_rank: Frequent Contributor
timestamp: June 08, 2020, 08:57:00 am
content: Hi all,I wonder if someone could help me.I'm looking for a simple, low cost BMS solution for two series li ion cells. All I want is over voltage, over current and under voltage protection. When there's a fault, the MOSFETs get switched off. TI don't seem to do over current and if they do the IC is horrendously complex for what I need. I've looked through Digikey and the usual suspects but nothing. I'm currently looking at designing something discrete which I really don't want to do for something safety critical.ThanksBoscoe

author: TimNJ
author_rank: Super Contributor
timestamp: June 08, 2020, 04:50:53 pm
content: Will this be installed mass-produced equipment? Or just personal? If it's mass produced, I'd highly recommend using an industry trusted lithium-ion protection IC. At least here in the US, people are getting sued left and right for improper lithium-ion deployment...regardless of which party is actually at fault. Voltage sensing I feel is easy to do correctly with discretes, but over-current (over-discharge), maybe a little more challenging to prove you have a robust solution. Typically those use a timers and delays to check for recovery conditions, etc.

author: nctnico
author_rank: Super Contributor
timestamp: June 08, 2020, 05:06:06 pm
content: Quote from: Boscoe on June 08, 2020, 08:57:00 amHow about using a readily made Li-ion battery pack? That is a much better solution; but make sure it has the right certifications.

author: Boscoe
author_rank: Frequent Contributor
timestamp: June 12, 2020, 10:28:59 am
content: Thank you for the replies and yes it's going to be implemented in a mass produced product. My other problem is that I can't use a dual MOSFET switch was the body diode drop is far too high at the currents it will be used at (~15A), I see drops of up to 1V in typical devices whereas I need something like 10mV!We have been looking into custom packs but our manufacturer does not provide BMS solutions.Currently I'm using a voltage monitor and a current trip sensor (INA300) to form HW interlocks with the rest of the circuitry. It seems solid to me but I've got a nagging feeling I'm doing something stupid. The interlocks will cut the charging source and any loads reducing the consumption on the battery to uAs from the MCU and glue.

author: bin_liu
author_rank: Contributor
timestamp: June 13, 2020, 03:37:32 am
content: It is best to provide detailed electrical parameters, such as the most important operating current.Generally, small current (such as 1A、2A) can use S-8232 of SII.https://www.ablic.com/cn/doc/datasheet/battery_protection/S8252_C.pdf

author: Lomax
author_rank: Frequent Contributor
timestamp: June 13, 2020, 12:36:57 pm
content: Maybe you've already looked, but for something like this I would turn toLinear Technology's datasheet search. You don't specify the capacity of your cells, or the desired input voltage, but I'm pretty sure you'll find a suitable chip in the LTC space. Perhaps something like theLTC4020is a good fit?
BMS Testing balancer using resistive load and PSU - Page 1
Forum section: electronics / projects

author: Blackgar
author_rank: Contributor
timestamp: March 13, 2022, 09:19:20 am
content: Build an BMS which includes active balancing (the LTC3300), before attach real cells, I want to do some tests.I just read the Manual for the Analog Devices Demo board:https://www.analog.com/media/en/technical-documentation/user-guides/dc2100bfa.pdfDoes the PSU they are using (HMP4000) have some special feature like sinking current or protection to reverse current? I don't find any information about this on the PSU's datasheet.I cant understand how the PSU is protected with this low value resistive load? I would expect some extra diodes an each positive output..
BMS that is worth a damn? - Page 1
Forum section: electronics / projects

author: rektm8
author_rank: Newbie
timestamp: May 24, 2021, 07:20:26 pm
content: I'm building a 4S4P pack out of Samsung 18650s and I'm disappointed that I can't seem to find a BMS which isn't a complete no-name made in China mystery board. Can anyone recommend a decent one? the pack I'm building is going to be 14.8v nominal at 60A.

author: rounin
author_rank: Regular Contributor
timestamp: May 24, 2021, 08:40:46 pm
content: I've used the BMS from Energus (https://www.energusps.com/shop/product/tiny-bms-s516-30a-16,https://www.energusps.com/shop/product/tiny-bms-s516-150a-750a-36) for prototyping / lab work.It is sort of for e-vehicle teams, expects to charge large battery arrays with non-real time balancing and a charger that will let the battery disconnect and reconnect a few times. eg the 750A BMS has a control for an external contactor to stop charge while it balances. The 30A one has an on-board fet.Somewhat janky, but it worked well enough. I mainly wanted it to e-stop an automated battery cycler if something bad happened. Didn't use it for more than maybe 50 cycles or so. Has a data logger port and configuration GUI that was functional.
BMW tail light PWM frequency - Page 1
Forum section: electronics / projects

author: poot36
author_rank: Frequent Contributor
timestamp: November 22, 2014, 05:45:43 am
content: Hi, I am needing the PWM frequency and duty cycle of a 2014 BMW motorcycles brake light / tail light for a circuit simulation. I just need the tail light mode but brake light mode would also be useful. If someone could measure this for me I would be greatfull. You can use a solar cell attached to a oscilloscope or maybe a computer sound card with the correct software installed so you do not have to take apart the bike. Mods if this is not the correct place for this topic could you please move it? Thanks.
BNC connector mounting - Page 1
Forum section: electronics / projects

author: Vgkid
author_rank: Super Contributor
timestamp: April 28, 2015, 04:23:50 am
content: How would one mount a female BNC pannel mount connector, without making the D shaped holes. Could I just titen down the nut all the way.

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 28, 2015, 04:49:58 am
content: Sure, people do it all the time. But you wouldn't have much protection against rotation.

author: kjs
author_rank: Regular Contributor
timestamp: April 28, 2015, 04:52:12 am
content: the D-shape prevents that the socket is loosening over time (and it will otherwise). I usually drill the hole pretty tight and put a very small amount of Epoxy glue into the D as a makeshift solution when I don't have a way to get them done properly. A pain to get the jack out again but better than always re-tightening the nut and a spinning jack.

author: Vgkid
author_rank: Super Contributor
timestamp: April 28, 2015, 12:31:16 pm
content: I think i will use epoxy, and titen the nut down tight. These will be on the back of a piece of equipment,no frequent removals.

author: smjcuk
author_rank: Frequent Contributor
timestamp: April 28, 2015, 12:45:00 pm
content: I buy the ones with flanges on rather than relying on the D. You have to drill 5 holes but it's easier to work with and they stay put.

author: TimFox
author_rank: Super Contributor
timestamp: April 28, 2015, 09:20:13 pm
content: If you drill a clean 3/8" hole, you can hit the panel just outside of the hole with a center punch and pick up some anti-rotation effect.

author: babysitter
author_rank: Frequent Contributor
timestamp: April 29, 2015, 05:22:01 am
content: enclosure made of thermoplastic? Drill a tight fitting hole and use a relatively cool soldering iron to press some enclosure material back into the hole.
BNC/Cal/USB Cover for Rigol DS1000Z (3D Printed) - Page 1
Forum section: electronics / projects

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 08, 2018, 09:41:34 pm
content: i thought of selling this as side income but well shipping cost with tracking number to international can be something. so i just share here (bnc_cap_acc.stl.zip)... my lab is a dusty collecting space so i need to cover as much, plus the colorful scheme can be fun addition esp i love the pinky one

author: rstofer
author_rank: Super Contributor
timestamp: April 08, 2018, 11:50:43 pm
content: That's a great project, thanks for posting it. I have been looking for an excuse to buy a 3D printer and maybe this is it.

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 09, 2018, 01:42:46 am
content: if you want to find an excuse (many excuses actually), goto tohttps://www.thingiverse.com/and type what you want... art? medical? mechanical? electrical? military? its all should be there. i should post the model there too, but well, i need an excuse to open an account there. or maybe i had but i just forgotten it.
BNO055 High current draw at suspend mode ~180uA - Page 1
Forum section: electronics / projects

author: TrickyNekro
author_rank: Frequent Contributor
timestamp: January 03, 2020, 10:19:58 am
content: Hello to everyone and happy new year!I´ve made a design with Bosch´s BNO055 for a handheld device, unfortunately as the title suggests I get a horrifically high current draw when in suspend mode.The design is textbook, same as the one suggested by Bosch in their datasheet.PS0 = 0V, PS1 = 0V, ADD = 0V, bootloader inditor pin shunted at 0V (as indicated by datasheet, but later found out it is wrong, on their forums)I know the add pin has a weak pull-up, I removed the address pin to ground, no change (address changed normally so I would guess it´s not my soldering)I also dug out the bootloader pin, again no change.In between I changed also boards and IMUs to be sure that either is shot by a bad connection. Still the same...I also changed the suggested internal regulator value from 100n to 1u as indicated, still no luck.I am at a loss as of what might be the problem. The suggested current consumption when in suspend mode is 40uA, having 3 times as much is a bit unacceptable,as it brings the battery life from 5 - 6 months to barely 1.5 months at stand-by. (the rest of the board consumes 9 - 10uA when in suspend mode).I am currently starting to suspect a batch problem as many other people have reported same issues on Bosch´s forums:https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/High-current-consumption-of-BNO055/td-p/8364Still, If anyone has any idea on probable causes of the problem, it would be quite helpful!Thanks a lot in advance!Lefteris

author: mikerj
author_rank: Super Contributor
timestamp: January 03, 2020, 12:18:24 pm
content: Is your micro powered from the same rail that is connected to Vddio? I2C pull-ups connected to the same rail?

author: TrickyNekro
author_rank: Frequent Contributor
timestamp: January 03, 2020, 12:41:04 pm
content: Quote from: mikerj on January 03, 2020, 12:18:24 pmYup all same 3.3V rail, that was the point to begin with, no extra regulators or switches.Edit: Everything connects to a power plane (6 layer PCB), I had a "no buried / blind vias" rule to keep the cost down, but that made the board look like Swiss cheese, leaving little room for extras,or else I would have just powered the device from a single gate / buffer. Getting the BNO055 to work on the board was like a secondary mission, so I just followed the text-book design, expectingeverything to work, even the low power part. Since it´s such a highly integrated SoC, as soon as I was getting orientation data out of the damn thing, I gave it green light.
Board Current Consumption Changes when Touched - Page 1
Forum section: electronics / projects

author: GeorgeIoak
author_rank: Regular Contributor
timestamp: March 03, 2017, 02:15:46 pm
content: I've got a bit of an odd situation so I thought I'd post and see if anyone has any ideas. I've got some boards we built up which have a PSoC, an accelerometer, battery charger, and aLM3671-ADJ regulator. The regulator is set to produce 3.1V and has with the feedback network set with the proper poles (see schematic).Most boards come in and out of sleep just fine but some are not able to go below pulling ~5mA. While debugging and probing the circuit I noticed that if I touched one of the resistors or caps in the feedback network the current consumption would drop to ~100uA (which is correct) and stay at this level. If I then activate the vibration motor the circuit will return to pulling 5mA instead of ~100uA. I can touch the filter circuit, the current drops and I can repeat this cycle.I can monitor the switching node of the LM3671 and see it switch from PWM to PFM mode when the current consumption changes. Everything on these boards works as expected except for the current draw not able to drop under 5mA. To confuse matters this doesn't happen on all cold power starts (plug and unplug the battery).The board is very small so when I touch I cannot say exactly which part is being touched but if I touch the motor circuit I don't get the current drop so it seems like it's the feedback network on the LM3671 is impacted by the finger touch.Hopefully someone has some good ideas on how I can figure this issue out!

author: poorchava
author_rank: Super Contributor
timestamp: March 03, 2017, 02:27:43 pm
content: My guess would be, that the circuit is on the edge of being unstable and by touching it you introduce additional parasitics which push the circuit into oscillations, which causes additional current draw.

author: GeorgeIoak
author_rank: Regular Contributor
timestamp: March 03, 2017, 02:57:32 pm
content: I was thinking along those lines that perhaps the setting of the poles is more critical in low current situations. I'm not too sure though how to check and adjust other than trial and error which is difficult to do when this doesn't happen all the time.
Board Function Guessing - Page 1
Forum section: electronics / projects

author: GJS123
author_rank: Newbie
timestamp: June 08, 2015, 03:36:35 pm
content: Can anyone guess what the board in the attached pics does? It is in line with the DC supply to a piece of computing equipment. I thought is was a filter of some kind but the 6 pin DIP is an SSR or opto-coupler which makes me think boost converter???6 and 7 on the silk screen are two more blade terminals (the output, connected to the computing equipment supply input) in case it is not clear from the angle of the photo. The other two blade terminals are the input from the DC supply. I'm trying to find out now what the two two pin headers normally connect to.Thanks for any suggestions.

author: SeanB
author_rank: Super Contributor
timestamp: June 08, 2015, 04:54:13 pm
content: 6 pin dip is a relay.http://www.vishay.com/docs/83805/lh1501ba.pdfSo likely it is both a common mode choke and filter ( the inductors and the capacitors) with reverse voltage and overvoltage protection provided by the big transient supression diode, and a power on indicator driver, using the 2 small molex connectors to provide the switching and to connect the LED.

author: GJS123
author_rank: Newbie
timestamp: June 09, 2015, 06:57:11 pm
content: Thanks for your reply, SeanB. I'll report back when I find out what the two molex connectors are normally connected to.
Board identification problem(NAS Board ?) - Page 1
Forum section: electronics / projects

author: Zebrag
author_rank: Newbie
timestamp: September 10, 2017, 06:19:38 pm
content: I recently found a board which seems to be the mainboard from a NAS(Network Attached Server) but i can't find any info about it.The only identification code is TS8OB_LS V1.05 but I can't find anything .Any help would be much appreciated. I powered it on and connected to my router and the network led started flashing , but i couldn't find it in my network, I used Advanced IP Scanner and it doesn't show up.

author: Jeroen3
author_rank: Super Contributor
timestamp: September 10, 2017, 07:32:49 pm
content: Due to the 3 missing analog ports I think it's an DVR board.Edit: Check with wireshark if it transmits anything, it could be static ip.
board layout tips for LoRa + chip antenna - Page 1
Forum section: electronics / projects

author: niclatrique
author_rank: Contributor
timestamp: January 27, 2025, 10:40:06 pm
content: Hi,I design a small 60mmx x100mm 4 layer PCB for a LoRa module and a microcontroller. The stackup should be signal 1, GND, GND, Signal 2.The RF signal will end into a chip antenna. I know there should have no ground plane in the antenna region.1- Should I avoid putting ground pours on layer 1 and 4 (signal 1 and 2 layers) ?2- Is a perimeter via stitching is a good idea ? Will this make any difference ?I will add via stitching all across the board (not done yet).I've attached images of the top and bottom side. This is what I came up with so far. Far from being a professional, any other mistakes someone would notice, I am happily taking advices and comments.Thanks,

author: Benta
author_rank: Super Contributor
timestamp: January 27, 2025, 10:54:12 pm
content: One thing about chip antennas: it's an impedance-matched attenuator.You have enough board space, so why not use an inverted-F antenna instead? Better performance, and it's just PCB traces, saving cost as well.

author: niclatrique
author_rank: Contributor
timestamp: January 28, 2025, 12:35:18 am
content: Thanks for the advice.I am totally new to RF. It is the very first time I nclude it in a project. I thought about the nverted F antenna but I could not find any premade layout in the 902-928MHz range. There is no way I can start designing it by myself unfortunately.If you have a reference to a premade layout, I would be more happy to give it a try.The chip antenna I planned on using is the ANT-915-USP410 from Linx.https://www.te.com/en/product-ANT-915-USP410.htmlI chose this one because it has a fairly spherical radiation pattern.Thanks

author: freetoshare
author_rank: Newbie
timestamp: March 04, 2025, 02:28:40 pm
content: Please take care of the whole layout surrounding to Antenna and inner layers, because they will impact antenna performance significantly. Another alternative chip antenna from Leankon LK1840201 (https://www.leankon.com/product/lora-antenna-915mhz/) might more suitable for you, as very clear layout guidelines on their datasheet including inner layers, and they also provide free service for pre-simulation on your product to ensure the optimal antenna performance in the real world.They can offer free samples and evaluation board as well for easy implement of layout design.https://www.leankon.com/product/lora-antenna-915mhz/
Board to board connector - Page 1
Forum section: electronics / projects

author: Daxxin
author_rank: Regular Contributor
timestamp: January 14, 2019, 07:11:49 pm
content: need to connect 2 boards , actually my kicad project, in vertical like a sandwich , any hints for connector 50 pins(2x25) through holethat keep the boards atleast 2 inch space (connector pcb1 - extender connection - connector pcb2) ?

author: soldar
author_rank: Super Contributor
timestamp: January 14, 2019, 07:18:27 pm
content: How about using ribbon cable with IDE-type connectors?

author: Daxxin
author_rank: Regular Contributor
timestamp: January 14, 2019, 07:46:39 pm
content: Quote from: soldar on January 14, 2019, 07:18:27 pmHi , no need to disconnect and save space too , inside pcb areasomething like this ..but more space :

author: DaJMasta
author_rank: Super Contributor
timestamp: January 14, 2019, 07:54:23 pm
content: There are lots of options for this. You can go with traditional headers like those, if you need higher density than normal 2.54mm headers, you can go to the half size, 1.27mm which is still pretty common. You can also look into mezannine connectors, which are what are typical for very low profile, high speed board to board interconnects.Maybe have a search around digikey or your preferred distributor to see what is available and then look around to find the best price.

author: KL27x
author_rank: Super Contributor
timestamp: January 15, 2019, 01:51:04 am
content: FPC ribbons and connectors go up to 80 pins and beyond, and down to as little as 0.2mm pitch. They can get pricey at the smaller sizes. Probably not what you had in mind, but in case you're ever in a pinch.

author: Richard Crowley
author_rank: Super Contributor
timestamp: January 15, 2019, 02:06:29 am
content: Does the connector need to be structural, or just provide connectivity?IOW, will there be separate means of holding the boards, and maintaining their separation distance?What are the board real-estate constraints? Can you afford standard 0.1 inch pitch (2.6 by 0.3 footprint)?How much movement and/or vibration does it need to handle?

author: wictor
author_rank: Regular Contributor
timestamp: January 15, 2019, 01:53:23 pm
content: PCI Express connectors on both boards and pcb with traces between connectors.Well, if you don't need to disconnect, just make rectangular slot to both boards and route signals to the slot edge. Then make connector pcb between those boards with traces and solder together.Wictor
Board to board connector with jumpers - Page 1
Forum section: electronics / projects

author: wigman27
author_rank: Regular Contributor
timestamp: August 12, 2014, 12:27:39 pm
content: Hi,I am currently designing a project that I am hoping to make modular and require some board to board connectors, I have had a look at a few other threads on here that discusses this and they are great but I need mine to have jumpers. Sometimes I will want to make the connection and sometimes I don't.I am trying to combine the connector and the jumpers into one device. I am currently looking at using these and soldering them to the board.ConnectorJumperAt the moment I need approximately 24 connections and will have a maximum clock signal of about 30MHz.Is there a better option?Lee

author: mariush
author_rank: Super Contributor
timestamp: August 12, 2014, 01:40:06 pm
content: If they're good enough for USB 2.0 and USB 3.0, they'll probably be OK for connecting your boards.

author: void_error
author_rank: Frequent Contributor
timestamp: August 13, 2014, 09:28:41 am
content: It's probably the cheapest way too. The maximum clock signal you can push through depends mostly on your PCB design (and the devices used, of course). A good practice is to keep the high speed traces short.

author: wigman27
author_rank: Regular Contributor
timestamp: August 13, 2014, 09:31:42 am
content: Quote from: void_error on August 13, 2014, 09:28:41 amCheapest isn't really my preference in this particular case so if you know of an alternative then I would be happy to hear it!Quote from: void_error on August 13, 2014, 09:28:41 amWhat sort of frequency would you consider high speed? when does it cross that "boundary"?

author: void_error
author_rank: Frequent Contributor
timestamp: August 15, 2014, 09:21:44 am
content: Quote from: wigman27 on August 13, 2014, 09:31:42 amThere's no defined boundary, since it depends on a particular case. Every PCB trace (or piece of wire) has resistance and inductance, and two adjacent traces form a capacitor. At low frequency this usually doesn't matter. The signal source's output resistance might also matter.

author: tszaboo
author_rank: Super Contributor
timestamp: August 15, 2014, 10:11:58 am
content: Quote from: wigman27 on August 13, 2014, 09:31:42 amSamtec has some measurement reports on their similar connectors. I remember it is in the "few GHz" region for the -3dB.

author: David Hess
author_rank: Super Contributor
timestamp: August 15, 2014, 09:06:51 pm
content: Those are the type of connectors I would use.Pin headers with 0.1 inch spacing are good enough for clean 100 MHz performance in oscilloscope vertical amplifiers so they are good to at least 500+ MHz when used appropriately.
Board to board right angle smd connector - Page 1
Forum section: electronics / projects

author: msr
author_rank: Regular Contributor
timestamp: April 16, 2014, 12:11:52 am
content: Hi everyone,I always struggle finding new connectors.Can anyone suggest me a board to board right angle smd connector? The pitch should be less than 2.54mm. 1.27mm would be nice.Basically I want to attach two boards side by side so the connectors should also provide some kind of lock mechanism.Additional hints are also very welcomed. How do you search for specific connectors? I usually use mouser which is the distributor I mostly use then I setup the filters and sort the results by price. But the results are kind of limited and this process doesn't seem very efficient to me. On the other hand using the website of the most famous brands (such as samtec, molex, te) leads me to the most expensive ones. I just want a cheap but (very?) specific connectoredit: another requirement, the number of pins should be around 16 ~ 20, so double row would be most appropriate than single row

author: msr
author_rank: Regular Contributor
timestamp: April 17, 2014, 01:28:03 pm
content: Anyone?

author: krivx
author_rank: Frequent Contributor
timestamp: April 17, 2014, 01:45:20 pm
content: I have used edge connectors, where the mating board had copper fingers in the PCB pattern. (something like thishttp://radionics.rs-online.com/web/p/edge-connectors/7676904/) These may not be suitable if you have tight space requirements.Another cheap solution is surface mount right-angle pin headers (http://radionics.rs-online.com/web/p/pcb-headers/7676730/).I would be careful with going all surface-mount, if the connectors are taking a lot of force (from many detach-insert cycles) they may rip off the board.

author: miguelvp
author_rank: Super Contributor
timestamp: April 18, 2014, 02:50:30 am
content: Mouser and others have parametric searchesFor example:Connectors > Board to Board & Mezzanine Connectors Mounting Angle=Right Number of Rows=2 Number of Positions/Contacts: Multiple Values (16-20)Resulting pitch on choices are 2mm then 1.27mm and under
Board to wire options in a space constrained board - Page 1
Forum section: electronics / projects

author: girishv
author_rank: Regular Contributor
timestamp: July 04, 2020, 01:42:41 pm
content: I have a design which needs to fit in 10mm x 15mm size. I need two pairs of board to wire connections (battery and motor). The device is battery operated and the wires are expected to carry 500 mA or less.The connection need not be mechanically strong. The SMT connectors I found have two additional pins for mechanical strength and occupy lot of real estate.Can I do anything better than pin headers with 1mm pitch?

author: tooki
author_rank: Super Contributor
timestamp: July 06, 2020, 01:58:18 pm
content: There are likely hundreds of connectors out there that meet that criterion. Browse JST's website for example. I see numerous fine-pitch SMD connectors without mechanical supports.

author: jbb
author_rank: Super Contributor
timestamp: July 06, 2020, 10:30:41 pm
content: If absolute minimum space is required, rigid flex PCBs can be helpful but expensive to prototype. No connectors are the smallest connectors, and flex PCB can be shaped just right to connect to your stuff.Alternatively, could your design could fit on a 2 layer flex PCB with a stiffener behind the electronics? This has been very effective and a lot cheaper than true rigid flex.

author: nctnico
author_rank: Super Contributor
timestamp: July 06, 2020, 11:14:20 pm
content: Quote from: tooki on July 06, 2020, 01:58:18 pmYou have to be careful with JST. Not everything is available in small quantities.

author: tooki
author_rank: Super Contributor
timestamp: July 07, 2020, 05:16:44 am
content: Quote from: nctnico on July 06, 2020, 11:14:20 pmFair enough. Still, a ton of stuff is available from distributors.

author: girishv
author_rank: Regular Contributor
timestamp: July 08, 2020, 04:39:34 am
content: Quote from: tooki on July 07, 2020, 05:16:44 amThe two PIN headers are occupying lots of space. I will explore the JST portfolio and see if I can find something.
bob parker ESR meter - Page 1
Forum section: electronics / projects

author: electros6
author_rank: Regular Contributor
timestamp: December 10, 2013, 02:04:21 am
content: Hi guys ,sorry about my English , In bob parker ESR meter , In ADC section it is mentioned that the micro-controller start counting the output pulse from the capacitor under test . Since the input to the test capacitor is pulse how the output pulse affected by the capacitor and how the pulse count vary depend on the capacitor

author: dannyf
author_rank: Super Contributor
timestamp: December 10, 2013, 03:00:39 am
content: You could benefit from reading the original document a few more times.The ADC is done via a comparator - it compares the (pulsed) voltage ramp on the DUT (the "ramp" on the dut will be mostly due to the ESR + some charge-up of the capacitor. Due to the very short charge-up time, the 2nd effect is minimized) vs. the voltage ramp on a standard capacitor. Initially, the voltage ramp on the DUT, after being amplified, will be higher than the voltage ramp on the standard capacitor -> the comparator output pulses.Until the point where the voltage ramps up sufficiently on the standard capacitor -> "missing pulse".It is a crude form of ADC but necessary due to the very fast charge up time on the dut - necessary to prevent the dut to be materially charged up.

author: dannyf
author_rank: Super Contributor
timestamp: December 10, 2013, 03:02:11 am
content: BTW, many modern mcus offer capacitive sensing units (CTMU). Using such mcus would have greatly simplified the design here.
Bob Smith chassis connection for plastic enclosure? - Page 1
Forum section: electronics / projects

author: philby
author_rank: Contributor
timestamp: February 07, 2023, 05:39:35 am
content: I am designing an ethernet product that will be fitted into a plastic housing.Until now, I’ve always had a metal enclosure to treat as chassis ground and connect my bob smith termination to through a 1nF 2kV capacitor.I’m having trouble finding any application notes on what to do with this termination for plastic enclosures.I’ve found these two application notes that suggest the high voltage capacitor “helps in filtering the noise residue managing to leak out through the transformer” and “provides a discharge path on the unused pairs”.https://www.ic72.com/pdf_file/l/151743.pdfhttps://ww1.microchip.com/downloads/en/Appnotes/VPPD-01740.pdfConnecting the 1nF 2kV capacitor to my 0V signal plane seems the wrong thing to do, but the first application note above suggests “A chassis ground plane can be added to the layer stack. Place this plane directly next to a ground plane to create a very tight capacitive coupling between the two planes”.Any thoughts or advice would be much appreciated.Kind regardsPhil

author: Siwastaja
author_rank: Super Contributor
timestamp: February 07, 2023, 10:24:07 am
content: You can connect the "chassis GND" to your ground plane but then you lose the galvanic isolation which is one of the big advantages of Ethernet, IMHO. Raspberry Pi does this.I had similar situation (100M ethernet, plastic case) and just left the chassis ground as its own small region under the connector, and quite obviously, with just plastic enclosure, it does not connect anywhere further. Was first-time pass in emissions and immunity, radiated and conducted and ESD. With 2.2ohm series resistors for edge rate control and 100M Ethernet compatible ESD TVS array. Did not test without these components.I connected CHASSIS_GND to GND using two of the 2kV MLCCs just to reduce impedance.Note the possibility of confusion: the bob smith termination network in itself contains a 2kV capacitor to CHASSIS_GND. This does not mean it has to be the only 2kV MLCC in the system. You can further connect CHASSIS_GND to GND withanother2kV MLCC, maintaining functional insulation (DC) between the grounds.

author: philby
author_rank: Contributor
timestamp: February 07, 2023, 11:33:34 am
content: Quote from: Siwastaja on February 07, 2023, 10:24:07 amI'm sorry but I don't follow. If I connect the 2kV cap to my 0V plane rather than to what would normally be my chassis ground, how is the galvanic isolation lost? Are you assuming/suggesting that the RJ45 shield would also be connected to 0V plane? I was just going to leave the connector shield unconnected.Quote from: Siwastaja on February 07, 2023, 10:24:07 amThanks for the insight. My feeling has been that it is not really necessary that that kind of confirms it.Quote from: Siwastaja on February 07, 2023, 10:24:07 amI have been considering that too.
Bodge of the day - Page 1
Forum section: electronics / projects

author: NivagSwerdna
author_rank: Super Contributor
timestamp: October 06, 2018, 05:38:23 pm
content: So I go to a PCB that I have had for ages but have never fully populated.... the intention is for a P-channel MOSFET to act as a high side switch to power on/off an external peripheral. Install a NDS332P which I have lying around (I never marked the actual part number on the schematic!) and then notice that the schematic has an N-channel (!) so now my footprint is wrong. where D is I need S, where S is I need D and G is correct.Bodged by standing it up, the wrong way up with a wire from the D to the pad.Seems to work though!

author: djacobow
author_rank: Super Contributor
timestamp: October 06, 2018, 08:12:31 pm
content: BTDT.In the famous words of National Academy of Engineering Fellow Missy Elliott:"I put my thing down, flip it and reverse it"
Boeing 777 switches for auto pilot - what are they called ? - Page 1
Forum section: electronics / projects

author: ez24
author_rank: Super Contributor
timestamp: July 30, 2015, 07:17:41 am
content: From a link in another thread is a video of a 777 simulatorhttps://au.news.yahoo.com/thewest/latest/a/22235213/flight-recreated-in-777-simulator/In this video they turn a knob and the digital display changes. Then when the desired reading shows on the display the knob is pushed in to engage.So the switch rotates (I assume an encoder) and pushes in.Is there a special name for this type of switch or control? Sure would make a cool power supply control. especially saying "engaged"thanks

author: German_EE
author_rank: Super Contributor
timestamp: July 30, 2015, 08:25:35 am
content: If you look on the website of ALPS there are plenty of rotary encoders with switches, the particular switches used in an aircraft may however be of higher specification and therefore expensive.
Boiler Control - MATLAB - Page 1
Forum section: electronics / projects

author: XaviPacheco
author_rank: Regular Contributor
timestamp: July 04, 2018, 08:31:55 pm
content: Hi,I want to simulate a boiler, and control some factors such as temperature, pressure, etc. Like controlling the temperature of a water tank using a PID loop. I do not have a physical boiler to determine its response and "real transfer function". I just want a simulation model where I can play with it, determine transfer fuction using models etc. I've been searching for it in the web with no success so far. So I guess I would have to build a new complete model by myself in MATLAB/Simulink, but I'm not so expert at it. That's why I'm looking at least for a starting point. Does anyone have sort of experience with this kind of control systems? Is this possible at all? I would appreciate any advice.

author: JS
author_rank: Frequent Contributor
timestamp: July 05, 2018, 11:19:48 am
content: You can do whatever you want with matlab...For your application and skill levels start with simulink, make a simple simulation, then add block by block till you get to the entire model.The hard thing is to know what modules to add so the numbers make sense to what you are thinking... First, are you thinking? What about? Do you know the math behind that process you are thinking? Then it should be preeeety stright forward to build a model, but the math of the blocks and the topology of the loop are quite tricky sometimes, depending on what features do you want in your model.JS

author: rstofer
author_rank: Super Contributor
timestamp: July 05, 2018, 02:44:19 pm
content: Simulink is a wonderful tool! I use it all the time to play with differential equations and it really is as easy as stringing elements together.https://www.mathworks.com/discovery/pid-control.htmlThe difficulty will be in coming up with the step response of the 'plant'. How much heat needs to be added to cause boiling at some temperature/pressure? Google is your friend in terms of coming up with equations for boiler controls.Yesterday I was playing with the Ball-Thrown-In-Air problem which is really just algebra, no differential equations involved. I have attached a drawing of the Simulink project. It really is plug-and-play!I wouldn't be surprised if the differential equation for the plant comes out looking like a second order equation much like the Mass-Spring-Damper problem (or the R-L-C circuit).You can add switches, knobs and dials to the Simulink project. This makes it easy to modify parameters. Of course you have to run the simulation after every change. That's one reason why I like working with real analog computers, the knobs work in essentially real time if the computer is in Repeat Operation mode.In the case of the Mass-Spring-Damper problem, it is fun to tweak the spring rate and watch the frequency change while adjusting the damper factor adds or removes oscillations and their related excursions (overshoot).
Boiler Power Off Sensing Circuit - Page 1
Forum section: electronics / projects

author: WL7JA
author_rank: Newbie
timestamp: October 29, 2014, 08:39:58 pm
content: I am trying to build a Sensing circuit for a Bosch on demand Boiler for a Heated floor. Right now I have switched to boiler via relay to the set temp thermostat. So when theBoiler calls for heat switches the AC Load on and from there I just have an array of 12volt LEDS lights up on the AC Leg. What I want to do is build a simple circuit or not. That whenthe boiler is not longer calling for heat it switches power off state (Already Does this) will switch over to say a 9 volt or 12 volt battery and lights say a Red LED and when the boilercalls for a Heat Green Led Comes on. I haven't looked at the Circuit board on the Bosch 2400ES yet. Although I have been looking a UPS Circuit board.....But still looking....Any Ideaswould be really helpful....73's de WL7JA

author: fcb
author_rank: Super Contributor
timestamp: October 30, 2014, 07:51:10 am
content: Your boiler is likely to have a fan in it, you could tap that (even with a mains rated relay or opto-coupler) to sense the boiler running, else there will be a gas control valve - sense the feed for that. If you want something a little less invasive then you could sense the mains current draw to the boiler, or even the exhaust gas temperature with a therocouple.

author: SirNick
author_rank: Frequent Contributor
timestamp: October 30, 2014, 08:38:33 pm
content: I didn't quite follow your description, but... (disclaimer: I'm not an HVAC expert)Usually there will be a 24vAC PSU somewhere with one leg of the transformer going through a thermostat switch, the other side of the switch going into the boiler, and the boiler returning to the transformer.Depending on how integrated your system is, the switch may actually connect to a zone valve instead of the boiler itself. The zone valve may then have an end-switch that connects to the boiler to tell it when to fire up, or the boiler may sense this based on water temp and/or flow.Either way, if this is what your system looks like, you may be able to tap into the 24vAC loop with an opto-coupler. When the thermostat calls for heat, it will close its switch and complete the loop. Therefore, you could connect an opto-coupler directly on the boiler side of the thermostat switch, with the other side directly to the 24v return. This will light up the opto when the switch closes. Keep the load light -- those transformers are usually on rated for an amp or so... give or take half an amp.
BOM for Adafruit nRF52840 Feather anywhere? - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: March 26, 2025, 03:11:45 pm
content: Hi,does Adafruit not share BOMs for projects?They do share the schematics but cannot find the BOM anywhere for the Adafruit nRF52840 Feather:https://learn.adafruit.com/introducing-the-adafruit-nrf52840-featherI just want to cross check something, does anybody know if the BOM is available and where to download it from?Thank you
Bond the PCB and power supply -Vo to the aluminum case? - Page 1
Forum section: electronics / projects

author: mikemontauk
author_rank: Newbie
timestamp: February 10, 2022, 02:25:13 am
content: [ Specified attachment is not available ]Basic Question - Do I bond the PCB ground plane and power supply -Vo to the aluminum case? Using conductive standoffs?

author: mikemontauk
author_rank: Newbie
timestamp: February 10, 2022, 02:57:17 am
content: Just clarifying the solenoids are open frame and will always be isolated (mounted to ABS plastic parts). The solenoid coil should be well isolated from the frame.
Book Suggestions: High voltage regulation - Page 1
Forum section: electronics / projects

author: valvedoctor
author_rank: Contributor
timestamp: July 20, 2016, 01:10:38 am
content: Hi all, when I say "high voltage", I really mean 300-400vDC, around 200ma. Just looking for some technical reading that could assist in the design of such.Linear supply with solid state regulation.Regards,DocSent from my iPhone using Tapatalk

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: July 20, 2016, 02:01:25 am
content: 500 series Tektronix service manuals. Of course, assuming you meant linear and tube-based.

author: valvedoctor
author_rank: Contributor
timestamp: July 20, 2016, 02:32:21 am
content: Doh, I never even thought to include the topology! I'm actually looking for solid state linear regulation.Sent from my iPhone using Tapatalk

author: PartialDischarge
author_rank: Super Contributor
timestamp: July 20, 2016, 02:41:53 am
content: Get the art of electronics, there are some PS designs scattered around the book in that range. Besides, its easy to scale mosfets, resistors, etc... in linear designs to handle those output voltages.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: July 20, 2016, 03:08:39 am
content: Quote from: valvedoctor on July 20, 2016, 02:32:21 amWell... with a name like Valvedoctor... And those values...

author: David Hess
author_rank: Super Contributor
timestamp: July 20, 2016, 11:41:40 am
content: What kind of output voltage range do you want? A limited output voltage range allows for a fixed high voltage level shift between a low voltage the error amplifier and the pass element.While probably not the kind of design you want, check out the service manual for the 320V 100mA HP 6209B power supply.For something simple, you can always add a high voltage transistor cascode to the input of a floating regulator like an LM317. Check out figure 11 on page 6 of Linear Technology application note 2:http://cds.linear.com/docs/en/application-note/an2f.pdf

author: Rbastler
author_rank: Frequent Contributor
timestamp: July 20, 2016, 01:18:33 pm
content: I've build both of these two tube power supplies:http://www.jogis-roehrenbude.de/Bastelschule/Funkschau-Netzteil-Schaltung.jpghttp://www.jogis-roehrenbude.de/Rim/Netzgeraet-S.jpgI prefer the first one. It's much better. The voltage is much more stable under load, even puls loads.Here is the schematic for testing the power supply I found online:http://www.jogis-roehrenbude.de/Leserbriefe/H.M.Sauer/Netzteil-Tester/Netzteil-Tester.htmEdit:Here's the article on "Jogis Röhrenbude" about the power supply:http://www.jogis-roehrenbude.de/Bastelschule/Funkschau-Netzgeraet.htm

author: cncjerry
author_rank: Unknown
timestamp: July 20, 2016, 03:14:05 pm
content: There's a bunch of high voltage supplies in older copies of the Amateur Handbook. Don't remember seeing regulated supplies but they could be in there.

author: daqq
author_rank: Super Contributor
timestamp: July 20, 2016, 05:18:37 pm
content: Try here:https://www.apexanalog.com/products/matrix_high-voltage.html