hybridfree/eevblog-posts huggingface dataset:
Powering part of circuit from output of logic chip - Page 1
Forum section: electronics / projects

author: Mat
author_rank: Contributor
timestamp: March 17, 2013, 08:52:26 pm
content: Hello everyone!Just a quick question. Here is what I want to do : power the "secondary" of a digital isolator from the output of a shift register to enable or disable communications to that part of the circuit. The max current output of the shift register chip is of course enough.Would there be any obvious reason for that not to work?Thanks!M.

author: Mat
author_rank: Contributor
timestamp: March 17, 2013, 10:29:51 pm
content: Nevermind, found a better way to achieve the same thing with what's called a "bus switch".M.

author: penfold
author_rank: Frequent Contributor
timestamp: March 17, 2013, 10:34:09 pm
content: Assuming this shift register is on the secondary side of the isolator and has an isolated power supply, then its possible and would work but would not exactly good practice.You may be well considering something like an AND gate with the signal in order to pass or block it, you could also use a transmission gate etc.

author: Mat
author_rank: Contributor
timestamp: March 17, 2013, 11:15:40 pm
content: Thanks!Yeah I figured it was not good practice...The problem with the AND gate is that the signals to be switched are bidirectional (I2C).I think I will be using the following chips :- ISO1540 I2C isolator- and then, on the isolated side, SN74CBT3306 to switch the signal on or offI suppose I need pull-up resistors before the isolator, between the isolator and the switch, and after the switch, otherwise, it won't work..M.

author: penfold
author_rank: Frequent Contributor
timestamp: March 18, 2013, 09:25:37 pm
content: Just a hunch, but assuming that the bus switch is purely bi-directional, which by the looks of it, it is. Then you shouldn't need the extra pullups either before or after the switch.Sorry for the immediate 'state the bleeding obvious' post but I'd already written it by the time you'd replied
Powering target device using a USB charger  - Page 1
Forum section: electronics / projects

author: AussieBruce
author_rank: Regular Contributor
timestamp: May 28, 2022, 02:03:21 am
content: Hi, I’ve googled this intensively, and nothing seems to hit the nail on the head….I’m working with a protoboard with a USB connector for power and connectivity. The nice thing about it is that it comes with enough information to achieve programmatic access to the FIFOs in the USB interface chip, both ways. I’m designing an onboard application that will have the device running unattended, with just power being provided through the USB connector. Occasionally it will be connected to a host machine for uploading of data, and of course that connection will power the device.My question relates to powering in unattended mode. When connected to a host machine, the power lines in the USB cable provide (as far as I know) regulated 5V. For powering the unattended board I need an autonomous 5V power supply, there are heaps of plugpack units on the market that accept a USB cable, but all of them market as ‘chargers’, or if they aren’t so specified, the specifications tend to be vague.Unfortunately, no schematic of the board is available. Whether there are devices that may be damaged by voltages above 5 I can’t tell.Is there anything in the specification of these devices that ensure that if they are plugged into a straight USB port they won’t do any damage?

author: sleemanj
author_rank: Super Contributor
timestamp: May 28, 2022, 05:01:46 am
content: USB supplies are 5v by default, they can, putting aside failures and complete non-compliance, only output higher voltages with specific active negotiation between the device being powered and the supply.A "USB Charger" is a laypersons name for a USB power supply.Note that the supplymightlimit current in the default mode to 500mA or even less, but in practice, for your "usb charger" bought from a retail shop, it is incredibly unlikely to do so and you'll be able to draw the full rated current of the supply should your device need it.

author: tunk
author_rank: Super Contributor
timestamp: May 28, 2022, 10:12:24 am
content: IIRC, the original USB specs said that "5V" could be 4.75-5.25V (or was it 4.75-5.5?).Many of the cheaper USB power supplies have questionable safety and high ripple,check outhttps://lygte-info.dk/info/indexUSB%20UK.htmlor watch some of DiodeGoneWild'svideos on youtube.
powering up motor of a B&O stand with wireless relay module - Page 1
Forum section: electronics / projects

author: nickvick
author_rank: Newbie
timestamp: May 02, 2020, 02:18:32 pm
content: Hello Guys,First of all thanks for accepting me. Im a begginer of the electronics world.I have a question regarding this project im doing which is above my league of knowledge.I have an old B/O motorized stand and i wanted it to power it up with the (pictured) wirless relay board.The old connection was a 4 pin connection pictured below, i cant find anywhere the schematics for the motor so I can't even understand which type of motor it is.It has 4 wires coming out of it, 3 wires were connected to the pins (white, brown and yellow) while the 4th oddly (green)wasnt connected to any pin.Anyways i rewired them with longer wires to make the job easier.As far to my understanding, yellow and brown should be the wires that move the motor left and right, white should be neutral and green should be ground.Can any of you give me any advice on how to wire everything on the eletric boards with relays? and of course if this is possible this way and if i need something more than that.Thank you
Powerline adapter on surge protector. - Page 1
Forum section: electronics / projects

author: sam1275
author_rank: Frequent Contributor
timestamp: August 12, 2015, 05:31:06 pm
content: Hello everyone, I installed a pair of Netgear AV200 Powerline adapters, one side for modem is through normal power plug, another to my router is through Tripplite UPS on the surge protect socket, the LED are green indicates the link is good, and it works good too.But after I added another pair works as a different group, one router side on UPS, client side on a plug, I began to experience random packet loss, the LED are also green, but I get a few seconds connection loss every few minutes to hours, randomly.I know it's hard for them to get through a UPS with surge protection, but I don't want to risking my devices by connecting them directly to wall plug, are there any better idea? The wireless is also too weak to reach. Thank you...

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 13, 2015, 01:41:11 am
content: For that application, cheaper surge protectors are generally better.
PowerPc 403 - Does anyone have a working schematic? - Page 1
Forum section: electronics / projects

author: DARV
author_rank: Newbie
timestamp: June 15, 2020, 02:40:32 pm
content: Hi everyone!Hope you are safe and having a great time.I got 6 PowerPC 403 ICs in a not at all shady deal on eBay ^^So for the time being I'll be working on a PCB for the new old stock ( think so ) processors .However I still have serious doubts regarding the way to connect the processor, and I rather not do too much reflow since I'm very bad at it, nor blow the ic with high voltages.As far as I've researched it seems the PPC403 was really famous back in the early 2000s for some tv top box or something alike.For my project ( The Lüpposita board ) I've planed to use a MCU with USB to transfer the ROM/RAM data to the boardand the cheapest and freely available CPLD or FPGA available ( ¿Lattice? ) for glue logic if needed ( by reading the data sheet I would say is not required ).So, anyone by any chance does have a PowerPC 403 evaluation kit schematic or similar?or any information regarding the implementation ?Thanks!
Powerpole connector question - Page 1
Forum section: electronics / projects

author: cncjerry
author_rank: Unknown
timestamp: June 06, 2018, 06:12:43 pm
content: I need to feed 48V at 30A to a chassis of my design. I would like to have a disconnect so I was looking at PowerPole PP30 connectors. Do they connect together or is there a male/female equivalent? Also, I need a chassis or panel mount for the box. If someone has the part number that would take the PP30 or other sized powerpoles that would handle the current, that would be helpful. I was planning to use a blue and green PP30 for the power (can also use black) and if I don't need male/female, I was going to just hook them from the feed cable into a panel mount connector but I don't see the panel mount on mouser. I see some 'E' shaped clamps that will work fine.ThanksJerry

author: metrologist
author_rank: Super Contributor
timestamp: June 06, 2018, 07:59:07 pm
content: Personally, I do not like power poles. XT60 is a good connector and I've seen a few different ways to accomplish a panel mount, like soldering it right to the board.powerpoles are symmetric, just the plastic colors are different. Here is a bracket:https://powerwerx.com/anderson-1462g1-powerpole-mounting-clamp

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 06, 2018, 08:09:58 pm
content: Hmm, 1/4" QC terminals are in that range. (Tons of screw and barrier terminals too, but if you want a tool-free connection, that doesn't apply.)Tim

author: chris_leyson
author_rank: Super Contributor
timestamp: June 06, 2018, 09:51:15 pm
content: Probably overkill for 30Ahttp://dinse-us.com/wp-content/uploads/sites/2/2014/07/DINSE_Plugs_Sockets_US.pdf

author: cncjerry
author_rank: Unknown
timestamp: June 07, 2018, 02:22:12 am
content: Quote from: metrologist on June 06, 2018, 07:59:07 pmso are the powerpoles the same sizes for the various amp ratings? I was going to use the blue connectors, PP30. I can always cut a clamp like that if they aren't, just trying to minimize the custom work.

author: Bratster
author_rank: Frequent Contributor
timestamp: June 07, 2018, 04:11:24 am
content: Pp15/30/45 are all the same housing just different contacts/wire size.Sent from my Moto x4 using Tapatalk

author: cncjerry
author_rank: Unknown
timestamp: June 07, 2018, 05:41:19 am
content: Thanks
Power/signal to steering wheel, past/present? - Page 1
Forum section: electronics / projects

author: Renate
author_rank: Super Contributor
timestamp: December 17, 2021, 10:35:38 am
content: I wanted to add some buttons to the center padded part of my steering wheel (no air bag) for control of my on-board Android. A simple Bluetooth BLE HID with 6 buttons would about fit the bill. I already have a PCB with a 2032 cell that I use in other projects. The problem is that for immediate response I can't let it (totally) sleep. I think the current draw to keep it paired 24/7 might be more than I'd want to stick a 2032 cell with. There probably is room for 2 x AAA though.There is the horn button and I'm sure that I could steal 5-10 mA, with or without a DC converter. The horn relay won't mind.Anyway, the more general question is, how do they do it? Old vehicles (I believe) just used one contact on a rotating disk to make contact for the horn and used the wheel shaft as ground. Does anything use sliprings? Does anything use flex PC with about 4-5 turns? Does anything use regular cable? How many conductors do they use? Is it discreet or just power and one serial output? Or CAN bus?

author: Someone
author_rank: Super Contributor
timestamp: December 17, 2021, 10:40:44 am
content: Quote from: Renate on December 17, 2021, 10:35:38 amThats a "clock spring" in automotive lingo, very common on modern cars (airbag introduction onwards).

author: Renate
author_rank: Super Contributor
timestamp: December 17, 2021, 11:11:27 am
content: Ah, I see that "clockspring" was the keyword that I was missing.
PowerSSO-36 heatsink fastening - Page 1
Forum section: electronics / projects

author: Gothenlor
author_rank: Newbie
timestamp: October 14, 2021, 06:46:43 pm
content: Hi,I'm designing a pcb for a TDA7498MV, which is a PowerSSO-36 package with exposed pad up.Most of the designs I see are with glued heatsink or this kind of sketchy heatsink + fanhttps://ae01.alicdn.com/kf/HTB1EfqStMmTBuNjy1Xbq6yMrVXae/1-PCS-Computer-PC-Cooler-Northbridge-Chipset-Aluminium-Cooler-Heatsink-40mm-Fan-For-3D-Printer-Cooling.jpgSome designs uses screws to fasten the heatsink, like the Sure boardshttps://trevormarshall.com/class-d-tutorial/My design is made to be portable, so I suppose the most reliable approach is to fasten the heatsink with screws.Now what is the best method to do it ? Is there special types of spacers to put between the pcb and the heatsink for this type of IC package ?How to be sure the heatsink contact with the IC is even ?Another constraint is to drill and thread the heatsink for the screws.Any insight is welcome.Thanks

author: thm_w
author_rank: Super Contributor
timestamp: October 14, 2021, 10:02:31 pm
content: Is the case going to be plastic or aluminum? Could be possible to heatsink to the case.Have you calculated the dissipation?LCSC has a few with two holes:https://lcsc.com/products/Heat-Sinks_441.htmlThen you'd have to either use screw + nut to secure it, or soldered in PCB nuts. Even contact would occur if the screws are alternately tightened until some reasonable torque is reached.If its low dissipation I would consider the thermal epoxy, and maybe a silicone fill around that if you are worried about coming loose. I have some boards where they used glue/epoxy and its impossible for me to remove the heatsink by hand.

author: Gothenlor
author_rank: Newbie
timestamp: October 15, 2021, 07:22:01 am
content: Thanks,Dissipated power at full power is 10W, so not much. I will use a metal case and I thought of using it as a heatsink. But it would imply that the IC would be on the bottom of the board, and other bigger (taller) elements (like filtering selfs) on top of the board. Is this a good idea for a class D design ?Thermal epoxy sounds like an option, I didn't know it was so strong, I'll give it a try.

author: thm_w
author_rank: Super Contributor
timestamp: October 15, 2021, 10:28:19 pm
content: It might make layout a little harder, but if its done right should be fine.This is how my alientek amplifier looks.
Powersupply 30-50A @ 12V with PWM input 10-100Hz or so - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: June 15, 2021, 03:20:42 pm
content: Is anyone aware of an off the shelf power supply (ebay is good) with PWM capable input, output about 12Vdc with high current capability say 30A to drive a solenoid at between say 100 and 100Hz?

author: Terry Bites
author_rank: Super Contributor
timestamp: June 15, 2021, 04:54:24 pm
content: Not off hand, but get yourself a PWM DC motor controller and modify its oscillator.
powerzook - Page 1
Forum section: electronics / projects

author: Terry Bites
author_rank: Super Contributor
timestamp: January 16, 2022, 05:37:40 pm
content: I had Jacarta try and flog me Powerzook- I'm not sure I believe they can sense current in Single phase +N or 3 phase+N without cutting into the cable.Has anyone reverse engineered or figured out how it works? Or is it BS?https://www.jacarta.com/powerzook/

author: TheMG
author_rank: Frequent Contributor
timestamp: January 16, 2022, 07:24:03 pm
content: Looking at the installation manual once you clamp the device on the cable you have to rotate it to find a peak current reading then lock it into place.This would suggest likely a hall effect sensor to pick up the magnetic field from one of the wires within the cable.Without any way of sampling the voltage this probably depends on the voltage always being very close to nominal, and the PF very close to unity. In a datacenter the equipment is usually running from a double-conversion UPS so the voltage is very stable, and virtually all modern IT devices that consume a non-negligible amount of power have active PFC. That's probably how they can get away with only measuring current to estimate power consumption.Of course the technique of using a hall sensor to pick off the magnetic field of one wire in a multi core cable isn't likely to be super accurate, but it's probably sufficient for the intended application of the device.

author: Terry Bites
author_rank: Super Contributor
timestamp: January 18, 2022, 03:50:29 pm
content: The magnetic fields in a AC or DC power cable cancel eachother out- no Hall sensor will see any field to measure?

author: tszaboo
author_rank: Super Contributor
timestamp: January 18, 2022, 04:34:36 pm
content: Cables are not perfect. The three conductor in that cable will be as a triangle, and you can place the sensor directly opposing the neutral wire close to the phase. I am not sure how accurate this sort of measurement is in practice, but it's not the first time I see this method to measure current.If someone has test reports for such a setup, it would be interesting to see.
PPAK-5 pattern dimensions - Page 1
Forum section: electronics / projects

author: Emil
author_rank: Regular Contributor
timestamp: May 07, 2016, 04:59:05 pm
content: Does anyone have a recomendation for pattern/footprint dimensions for PPAK-5?(It's for an LD29150 LDO. The datasheet oddly enough has recomened patterns for DPAK and P2PAK, but not PPAK. There are some dimensions, but not enough to avoid some guessing.)
Ppice for TI anyone - Page 1
Forum section: electronics / projects

author: Terry Bites
author_rank: Super Contributor
timestamp: May 24, 2025, 01:27:25 pm
content: Hi. I thought I'd try it out but I'm baffled by some of the very basic stuff.Which is often the way now whre intuition counts for nothing and a only 3000 page read lies ahead. I have a life so,yeah.I cant find anything remotley like a battery or power source. There an "F" thing that offers a number of very (very) obscure options. Edidting them just changes their name.It doesn't creat a source of any kind. This is wierd. Videos assume you've already found this thing. I've seen example ciruits with batteies, wtf. The documentation doesnt offer any advice AFAIK.

author: D2236
author_rank: Regular Contributor
timestamp: May 24, 2025, 09:50:52 pm
content: Here is how you get to it in PSpice. The TI version may work the same.Place > PSpice Part > Source > Voltage Sources > DC

author: TimFox
author_rank: Super Contributor
timestamp: May 24, 2025, 10:04:09 pm
content: In regular Spice:The syntax for a constant DC independent voltage generator isVxxxxx N+ N- DC <value>For example:Vcc 10 0 DC 6In the Spice documentation, you can find all sorts of other things that can be added for sine, pulse, exponential, piece-wise linear, and fm time-dependent functions.E, on the other hand, is a voltage-controlled voltage source.
Practical controlled impedance LVDS routing? - Page 1
Forum section: electronics / projects

author: bitbanger
author_rank: Regular Contributor
timestamp: November 18, 2018, 06:36:27 am
content: Hi Folks -I see a lot of LVDS at work over long cable, and more and more have been asked to troubleshoot link integrity. I'm designing a small connector breakout board because the proprietary connectors are impossible to probe (as is inside the end-point devices). This is a small board, 1"x3" or so, with a male connector on one end, a female on the other (think micro-miniature DSUB connector) and some low-profile through hole test points meant for a differential probe. There are four differential pairs.Anyway despite the small board I need to make sure I'm doing my best to maintain signal integrity. Planning on just some 4-layer protos from OSH Park because this is out of pocket.The trouble I'm having is not the intricacies of the controlled impedance, it's just the logistics of crossing 4 matched pairs across even this small board. If you imagine one connector on the left, one on the right, the signals on the top left have to route to the bottom pins on the right conn. At first I was using the through-hole test points in the middle to get me to another layer so I could cross over, but this really killed ground plane continuity.I know vias are generally "frowned upon", but I'm wondering: would a good approach be to use vias all near the originating connector, just to get them all in the right "order", then route the 2-3" across the board, in straight fashion? In saying that out loud the way the test points are oriented, it would still make routing a pain, but perhaps less so.Right now the stackup I'm planning is ground plane on top, two pairs on Inner Signal layer 1, two pairs on Signal layer 2, then ground plan on bottom layer. Thoughts?Thanks in advance!
practical design of Linear Regulated power Supply - Page 1
Forum section: electronics / projects

author: Gurumurthy
author_rank: Regular Contributor
timestamp: May 15, 2017, 04:06:53 pm
content: please give me some reference for practical design of Linear Regulated power Supply and Various Pre regulator circuit using SMPS Technique to deign my Lab power supply (rating 30V, 5 Ampere).

author: Simon
author_rank: Unknown
timestamp: May 15, 2017, 05:37:57 pm
content: DO NOT triple post the same topic! if you do YOU WILL be banned!
practical DFM discussions - Page 1
Forum section: electronics / projects

author: mickpah
author_rank: Regular Contributor
timestamp: July 13, 2013, 02:52:00 am
content: Don't know if anyone has followed the Sparkcore porject on kickstarter?It's a YAAC (yet another arduino clone), this time with a WIFI twist.I have a passing interest in the project itself, but what is interesting to read is the engineering discussions and decisions being made as they move from prototype through the DFM process.Have a read herehttps://github.com/sprk/core/issues?state=closed
Practical gyrator circuits? - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: September 12, 2018, 02:00:11 pm
content: Here (https://www.eevblog.com/forum/projects/have-you-ever-seenused-a-power-gyrator-circuit/msg425405/#msg425405) NANDBlog mentions "they don't behave good". That is a pity, as I'd like to try this technique out. A BBC app note WHP093, "Taming the Gyrator" seems to have a way to quench spurious oscillations.I've seen a 2 op-amp version (Antioniou) in H&H, plus there is a one op-amp variety, also a Bob Pease "Floating inductor" type. No doubt more exist.Has anyone out there had "good" experience with some type of gyrator? That is, for instance, a negative or multiplied capacitor, or gyrated inductor etc - something that can be tuned over a fairly decent range?So far my experiments have stayed with a simple NIC (one op-amp, 2 resistors) and measuring effective capacitance of that in parallel with a normal capacitor. For 100n, I can 'tune' it down to 20n (so the NIC contributes "-80n"), beyond that my meter suggests resistance, then a negative capacitance. Therefore (not entirely un-surprisingly) the NIC fails as the effective value gets towards zero. I do wonder why I can't tune the NIC nearer to zero though. One possible issue is the meter was in auto mode, so might alter the test frequency.
Practical to make your own custom cable - Page 1
Forum section: electronics / projects

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: October 11, 2019, 12:35:34 am
content: Suppose I want a one meter length of cable about 5mm in outer diameter (.2 inches) that contains two thin 50 ohm coaxes and 5 or 6 24AWG wires... Think its possible to shove all that into a piece of 8mm (unshrunk) silicone heat shrink tubing and have it end up being a usefully flexible cable?https://www.ebay.ca/itm/Silicone-Rubber-Heat-Shrink-Tubing-0-8-40mm-Heatshrink-Tube-Black-Gray-Iron-Red/183851311036?var=691506500396I have no idea what this stuff acts like once shrunk or "recovered" in the heat-shrink tubing vernacular.Anyone ever try this?It would be for a Tektronix P6042 current probe, often the probe cable fails.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 11, 2019, 12:48:56 am
content: Think I'd recommend loom (e.g. the braid stuff) over tubing (spaghetti or shrink)?Tim

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: October 11, 2019, 01:00:49 am
content: Quote from: T3sl4co1l on October 11, 2019, 12:48:56 amI've done that before for my experimental Commodore SX-64 keyboard cable. It works, but it was not as flexible as I want this P6042 cable to be.

author: edpalmer42
author_rank: Super Contributor
timestamp: October 11, 2019, 02:22:50 am
content: A VGA cable has 3 coaxes and 5 signal lines plus assorted ground returns. Would that work?Ed

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: October 11, 2019, 02:30:06 am
content: Quote from: edpalmer42 on October 11, 2019, 02:22:50 amThose are 75 ohms and too thick... good idea though.

author: tautech
author_rank: Super Contributor
timestamp: October 11, 2019, 02:32:46 am
content: Quote from: Alex Eisenhut on October 11, 2019, 01:00:49 amIs the original cable FUBAR'ed ?IMHO replacing it with 'some other' coax will bugger up the cable termination impedance matching.You might want to have a read of Tek's Probe Circuits book P65 on.http://w140.com/tekwiki/images/6/62/062-1146-00.pdf
Practically smallest SMD size for assembly run of 1 to 100 pieces by PCBWay etc - Page 1
Forum section: electronics / projects

author: Wilson__
author_rank: Frequent Contributor
timestamp: April 28, 2024, 06:26:15 am
content: What is practically smallest SMD size, for making PCB and component assembly, for 1 to 100 pieces by PCBWay etc. for these components:Resistor (signal, no heat rating required)Power line by pass capacitorLED as visual indicators, charging and doneDo they x-ray inspect board with leadless chips, 1 x 1 mm and 2 x 2 mm, and masking sure there is no assembly error, no solder or shorted solder? They need to be correct as it is too small for me to debug or re-solder.Many thanks

author: xvr
author_rank: Frequent Contributor
timestamp: April 28, 2024, 09:48:09 am
content: Why not ask PCBWay directly? I guess they know what they do much better than EEVblog community.

author: charliehorse55
author_rank: Contributor
timestamp: April 29, 2024, 05:44:28 am
content: How small does it need to be? I use 0402 as standard for passives, never had a problem with it. I just ordered a board from them with ~600 components per board, had 3x3mm 9-pin QFN, SOT-23, and a few different ICs with 0.5mm pin spacing.They have x-ray inspection available for BGA and other high pin count devices, but normally they rely on optical inspection. It works quite well.

author: Wilson__
author_rank: Frequent Contributor
timestamp: April 29, 2024, 06:39:38 pm
content: Wonder any one experience on 0201 R?Wonder if they (highly skilled) manually pick and place, or use machine, on test sample run of quantity one? Board has 25 components and very small.PCBWay pcb spec is 0.1524 trace widet and spacing. PCB itself is good for 0201This photo is one of the well known RP2040 tiny board. 0201 R are used extensively.Many thanks

author: xvr
author_rank: Frequent Contributor
timestamp: April 29, 2024, 06:50:20 pm
content: Yes, they accept 0201PCBA capability page -https://www.pcbway.com/assembly-capabilities.html

author: Wilson__
author_rank: Frequent Contributor
timestamp: April 29, 2024, 09:30:41 pm
content: Many thankshttps://www.pcbway.com/assembly-capabilities.htmlPassive Component: we can accept components as small as 01005, 0201,0402.BGA: We have the ability to handle BGA of 0.3mm pitch for rigid PCBs and 0.4mm for flex boards with X-ray testing. (The details can be confirmed according to the board design.)Fine Pitch Parts: we can assemble 0.25mm fine pitch parts.Note: the 'normal-level' PCB making is up to 0201 although assembly is 01005. There is advanced-level service
Prc 320 lsb mod help - Page 1
Forum section: electronics / projects

author: Jesset1996.5
author_rank: Regular Contributor
timestamp: September 03, 2015, 01:46:07 am
content: Hello. Ive been having trouble figuring out how exactly i can build this. I wanted to do a lsb mod with a reed switch instead of cutting any wires or drilling any holes. Its been done before but its not well documented so i came here for help. I mainly need help with figuring out which resistors, and capacitors i will need. Theres so many types and i dont have the correct knowledge to know what type to use. If any other files or information are needed please do ask. Id be more than happy to provide them. Any help would be much appreciated! Ps: the file is to large to attach so ill just leave the link here.https://www.google.com/url?sa=t&source=web&rct=j&url=http://g8jnj.webs.com/PRC%2520320%2520Modifications%2520(V1.5).pdf&ved=0CB4QFjABahUKEwjA5cHL3tnHAhXDdh4KHVKtCrk&usg=AFQjCNGmmoKtrPdRTSoJTE6Z5lw9GqlmNg&sig2=0Cjwjh2NwSYiPaKml9qPlg
Pre-regulator based on MOSFET N  - Page 1
Forum section: electronics / projects

author: pitagoras
author_rank: Regular Contributor
timestamp: January 18, 2017, 01:44:11 pm
content: Hi,I've seen this pre-regulator in a circuit designed by @blackdog in this thread:https://www.eevblog.com/forum/projects/anything-wrong-with-this-linear-psu-design/75/Only that it pre-regulates the positive side and uses a P MOSFET.I converted it for using a more common N channel MOSFET (IRFZ44N) because it's really cheap and available.The sine input simulates the transformer.The zener and resistor just simulate the linear regulator. So the left side of R4 is linear regulator input, the right side is the output.I attach the ltspice sim and the included SCR model.I'm not really sure of what I am doingSo all comments and suggestions are welcome.

author: blackdog
author_rank: Frequent Contributor
timestamp: January 18, 2017, 03:34:09 pm
content: Hi pitagoras,Can you make the schematic more clear, its difficult for me te read itThere are more MOSFETS you can use, there is a lot of choice, this is only at Farnellhttp://nl.farnell.com/infineon/irf5210pbf/mosfet-p-100v-40a-to-220/dp/1704021http://nl.farnell.com/infineon/irf4905pbf/mosfet-p-55v-74a-to-220/dp/8648190http://nl.farnell.com/stmicroelectronics/stp80pf55/mosfet-p-to-220/dp/9935703http://nl.farnell.com/fairchild-semiconductor/fqp47p06/mosfet-p-channel-60v-47a-to-220/dp/2575367http://nl.farnell.com/infineon/spp80p06p-h/mosfet-p-ch-60v-80a-to-220-3/dp/2432734Do no use a zener just use a LT3080 or so, it must be in LT Spice.But I have no problem with the circuitry to convert an N-type MOSFETDo not forget the protection of de Gate.Select the MOSFET well, watch the peak current and the Vds.Kind regarts,Bram

author: pitagoras
author_rank: Regular Contributor
timestamp: January 18, 2017, 07:31:10 pm
content: Quote from: blackdog on January 18, 2017, 03:34:09 pmOk I added a zener accross G and S and adjusted to avoid max of 160A peak (now it´s 60A)I attach the graph of I(g) and Vgs,Breakdown Vgs for IRFZ44N is 55V, Max Id @ 10V = 49A, pulse drain current is max 160Awhat do you think?
Pre-twisted Mag Wire - Page 1
Forum section: electronics / projects

author: MattHollands
author_rank: Frequent Contributor
timestamp: September 26, 2017, 05:55:41 pm
content: Back in a lab I used to work in, we had reels of pre-twisted mag wire on a spool. This stuff was good for hooking up a scope and basic measurements as the wire was pre-twisted to minimise loop area and it was flexible and didn't need stripping. It was 30 or maybe 32 AWG, one was red and one was green so it was easy to follow.Now I can't find anything like this one the web and I'm starting to suspect that maybe our lab techs made this in house? Everything with a twisted pair seems to have an outer insulation which makes it stiffer and means it requires stripping etc.Anyone know where I could buy more of this stuff?

author: Monkeh
author_rank: Super Contributor
timestamp: September 26, 2017, 05:59:04 pm
content: Buy some cat5e and yank the pairs out?E:https://www.wires.co.uk/acatalog/tt_wire.html

author: MattHollands
author_rank: Frequent Contributor
timestamp: September 26, 2017, 06:08:48 pm
content: Cat5 twisted pairs have plastic insulation whereas I want enamelled. However the "50 Metres 2 STRANDS 0.10mm RED/GREEN Enamelled Copper Wire & Double Silk" looks promising.

author: Monkeh
author_rank: Super Contributor
timestamp: September 26, 2017, 06:10:13 pm
content: Quote from: MattHollands on September 26, 2017, 06:08:48 pm*shrug*, it shrinks right off with the touch of an iron.QuoteHair thin. The 0.19mm should be closer to what you've used.

author: langwadt
author_rank: Super Contributor
timestamp: September 26, 2017, 06:12:02 pm
content: Quote from: MattHollands on September 26, 2017, 05:55:41 pmplenty of google and ebay hits for "twisted magnet wire"

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 26, 2017, 06:19:07 pm
content: Bifilar.

author: Monkeh
author_rank: Super Contributor
timestamp: September 26, 2017, 06:20:18 pm
content: Quote from: T3sl4co1l on September 26, 2017, 06:19:07 pmIsn't bifilar figure 8 shaped?

author: MattHollands
author_rank: Frequent Contributor
timestamp: September 26, 2017, 06:20:54 pm
content: Quote from: langwadt on September 26, 2017, 06:12:02 pmYep, plenty of google and ebay hits for a lot of things. But all the ebay results for this search are in the US and have high shipping cost and most of the other results that turn up either require getting a quote which is always a pain unless you have a large order.
Preamlifier for dynamic micro - Page 1
Forum section: electronics / projects

author: eak
author_rank: Newbie
timestamp: March 01, 2013, 01:54:00 pm
content: Hi guys,I have been working on a preamp for my dynamic micro, based on 2 npn, i made a pcb etc, but it doesn't workwhereas on a bread board using BC546b it worked just fine, at least one stage, i didn't try to test with 2 transistors. Since i have not any scope, i just mesured the working point, it is about 7V with 9V vcc, it have shifted a litle bit. In theory i calculated the resistors to have 5V (~Vcc/2).. i can't understand why i have nothing on the output. I put some pics of the pcb and schematic if you want to see them.

author: amspire
author_rank: Super Contributor
timestamp: March 01, 2013, 02:35:35 pm
content: Quote from: eak on March 01, 2013, 01:54:00 pmI haven't checked your board layouts, but a few things. You said two PNP transistors - I assume you meant two NPN transistors.In your circuit diagram, C1 and C4 are around the wrong way.The best way to get help is to post the circuit with measured voltages on the base, collectors and emitters.

author: eak
author_rank: Newbie
timestamp: March 01, 2013, 02:58:58 pm
content: 2amspireOps, i think you're right about capacitors! I measured it, at Vcc=9V both have :Vb = 2.8VVe = 2.15VVc = 6.85 VPS yes these are NPN, thanks

author: amspire
author_rank: Super Contributor
timestamp: March 01, 2013, 03:14:14 pm
content: Quote from: eak on March 01, 2013, 02:58:58 pmThat all looks good. How does the ground fills connecting to the emitter 1K resistors connect to the rest of the ground fill? The images are a bit big to easily see without downloading, so I haven't looked at all the images.Edit: I just realized the connection is under the transistor. It looks like it should work. Have you tried attaching a precision calibrated signal injector (ie your finger) on the transistor bases and see if you get an output? It sounds to me like there is something is shorting out the signal somewhere in part of the circuit isolated by the caps (ie not directly connected to a transistor. Perhaps on the volume input.

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 01, 2013, 07:09:20 pm
content: Quote from: amspire on March 01, 2013, 03:14:14 pmI click on the link to the picture, my viewer then scales the image.QuoteYes, you might be right. Otherwise the Ve of 2.15V would not be possible.The only thing I can come up with is that pin 1 of your potmeter is connected to ground. It certainly looks a bit suspicious on the PCB, and that would effectively kill the signal without showing any strange voltages on the transistors.

author: eak
author_rank: Newbie
timestamp: March 01, 2013, 10:32:02 pm
content: 2amspireYes the ground is under the transistors. I changed the orientation of C1 and C4, i tried to touch the base with fingers, nothing.. I even shorted C3 , because i noticed that C3 and C4 in series would give only 5uF..nothing changed. So i give up, i will test it with a scope at university.

author: eak
author_rank: Newbie
timestamp: March 05, 2013, 05:07:26 pm
content: it works ! there was an open circuitthanks to all
Preamplifiers - Page 1
Forum section: electronics / projects

author: Rickpercy87
author_rank: Contributor
timestamp: October 23, 2015, 02:31:38 pm
content: Hello, can anyone tell me the major differences between op amps? I have some but the spec sheet calls for lm324 amps. I'm basically boosting a microwave signal, around 100 hfe is what I need.Can I pretty much use any amplifier? I see too many differed types.

author: Marco
author_rank: Super Contributor
timestamp: October 23, 2015, 02:58:21 pm
content: Quote from: Rickpercy87 on October 23, 2015, 02:31:38 pmhFE is a metric for BJTs and a LM324 won't do much at microwave frequencies, you seem to have some major gaps in the necessary knowledge to even try to tackle this which won't be able to be filled by forum advice.

author: tggzzz
author_rank: Super Contributor
timestamp: October 23, 2015, 02:58:38 pm
content: Quote from: Rickpercy87 on October 23, 2015, 02:31:38 pmYour question is too vague to answer; you need to read introductory texts on opamps.You aren't using a lm324 at microwave frequencies, and op amps don't have an hfe.

author: GNU_Ninja
author_rank: Regular Contributor
timestamp: October 23, 2015, 03:41:29 pm
content: Whoa! That microwave stuff is a black art
Prebiased BJT vs MOSFET - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: January 21, 2015, 01:32:38 pm
content: Hi Everyone,So I can see that you can get prebiased BJT's in single or arrays at Digikey which are basically a single part solution from a uC to something you might want to drive with more current. I've been reading some on mosfets and it sounds like to do it the right way you should have a gate resistor and another resistor to pull the gate off/on when tri-stated.My question is for small loads 50mA or 150mA that you might want just switched or possibly to use PWM with like a led or led backlight, does the BJT work well as a lesser part count solution?Do they make mosfets with the resistors built in?

author: c4757p
author_rank: Super Contributor
timestamp: January 21, 2015, 01:49:05 pm
content: For a small MOSFET, the series gate resistor is totally unnecessary, unless the device is likely to suffer an ESD event. Also, you can omit the gate-source one if you can be sure that the gate pin will always be driven, or that being undriven briefly won't hurt anything.Switching a backlight? I'd probably go totally resistorless.That said, the prebiased BJTs are also nice - they are a bit more robust w.r.t. ESD and whatnot, have a pulldown built in, and have a lower threshold. I often prefer them.Your choice.

author: dannyf
author_rank: Super Contributor
timestamp: January 21, 2015, 04:45:23 pm
content: QuoteWhy do you need to have the resistors built in?

author: alank2
author_rank: Super Contributor
timestamp: January 21, 2015, 04:50:52 pm
content: I prefer a lower part count when given a choice, less for me to tweezer in place.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 21, 2015, 08:39:37 pm
content: It bothers me that I see things use expensive MOSFETs (>> $0.10/ea!) for teeny little signals like LEDs, when prebiased BJTs are better in all minuscule ways for the purpose (< $0.06/ea, no need of external resistors, softer current limit, little or no risk of parasitic oscillation, more ESD tolerant, etc.).Tim

author: rob77
author_rank: Super Contributor
timestamp: January 21, 2015, 09:06:29 pm
content: Quote from: T3sl4co1l on January 21, 2015, 08:39:37 pmmosfets for small currents are extremely cheap.. approx 0.02 Eur in 100s quantities ... e.g. BSS138 , BSS123, 2N7002.
Precautions to be considered when using LM338... - Page 1
Forum section: electronics / projects

author: Gurumurthy
author_rank: Regular Contributor
timestamp: June 17, 2017, 11:16:17 am
content: HI to all !!!!Please give me do and don'ts while working with LM 338. It could be a precautionary step to protect integrated circuits because it cost 100 Indian rupees.Help me in this regard!!!!

author: MagicSmoker
author_rank: Super Contributor
timestamp: June 17, 2017, 11:52:32 am
content: Oh for crying out loud, can you not do even the most basic research yourself? All you could possibly ever want to know about the LM338 is here:http://www.ti.com/product/LM338/technicaldocumentsStop typing and start reading.

author: digsys
author_rank: Unknown
timestamp: June 17, 2017, 12:28:01 pm
content: It has no unique quirks and is pretty rugged. Just ensure you are within all the operating parameters as described in the docs. There are also I/O protectionextras discussed. It's been around a very long time.
Precharge system for relays - Page 1
Forum section: electronics / projects

author: richcj10
author_rank: Unknown
timestamp: June 04, 2014, 04:25:45 am
content: I am working on this system to protect the contacts of the relays by "pre-charging" the other side. This system detects the "start" line go high and it should turn discharge off. It would then turn precharge (AIR BOT - Pre) on for 5 seconds and then turn AIR -TOP while turning off precharge. this works on the bench with a power supply. I put this in the project and it stops working immediately. There is nothing wrong with the wiring in the project. any ideas?

author: aargee
author_rank: Frequent Contributor
timestamp: June 04, 2014, 04:45:09 am
content: Not that I've looked at the circuit closely, but a number of my design transition problems from bench to application usually come down to the power supply and assumptions there of.Weaker, different, wrong voltage...

author: richcj10
author_rank: Unknown
timestamp: June 04, 2014, 04:47:35 am
content: I will take a look at the voltages....maybe a grounding issues?

author: David_AVD
author_rank: Super Contributor
timestamp: June 04, 2014, 05:47:11 am
content: From the MIC5014 data sheet:QuoteCan't see those caps on your schematic.

author: richcj10
author_rank: Unknown
timestamp: June 04, 2014, 01:59:47 pm
content: I noticed that. It is added on the board dead bug style across 1 and 4.

author: David_AVD
author_rank: Super Contributor
timestamp: June 04, 2014, 09:07:11 pm
content: What are the differences between the bench and and "real" setup ? Power, loads ??

author: David_AVD
author_rank: Super Contributor
timestamp: June 04, 2014, 10:20:13 pm
content: Quote from: richcj10 on June 04, 2014, 01:59:47 pmI don't know about anyone else, but it annoys me when people ask for help and the posted schematic is not the same as the actual one.

author: richcj10
author_rank: Unknown
timestamp: June 05, 2014, 01:49:06 am
content: Sorry about it. I thought of it earlier and tried it. forgot to mention it. I found adding more capacitance to the 5v rail helped.This is wired because there is already a 10uF cap on there after a 7805. Adding another 10uF fixed it. the 10uF cap (and 7805) is really close to this part of the circuit. Well, it works...
Precise DC Electronic Load questions - Page 1
Forum section: electronics / projects

author: DanioIO
author_rank: Contributor
timestamp: February 28, 2014, 08:04:53 pm
content: Hi,Im trying to design a DC Electronic Load and i want to ask what op amp should I use to control the mosfet. I'm trying to make this project as precise as i can so i dont mind buying a expensive op amp, but should it be a low noise, low offset or low drift? Op amp will be control by a 16 bit DAC.Other question can i use a instrumental amplifier to measure voltage drop on a sense resistor and connect the output to the mosfet feedback op amp? I will use a small shunt resistor (about 0.01R) so i would need to add gain to the loop.The voltage drop (current) and input voltage will be measured by a ADC and used to calculated the correct DAC value for constant Power or Resistance mode. Should i use a fast ADC to prevent any oscillation in the circuit created by the delay from measuring current/voltage and setting the MOSFET value. Im thinking about using 10-50Hz ADC.What other thinks should i consider in this design?
Precise magnetic field inside solenoid - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: November 22, 2019, 12:30:23 am
content: Hi All,I am trying to find an accurate formula for the magnetic field strength/density along the Z (revolution) axis of a solenoid. I need to input it in Excel so I can play with the values.No idea how to use/calculate integrals in Excel so if possible either a formula that can be approximated to a non-integral reduction of it or if someone has one already in Excel and is willing to share it that would be great.As input ideally the physical dimensions as well as the current. As output the strength along the Z axis of the solenoid.ALSO A QUESTION: One thing I noticed is that a lot of the formulas I came across don't account for the length of the solenoid (just the number of turns). Am I right in thinking that 500 turns on a single layer product a different magnetic field density/strength inside the solenoid along its rotation axis which is different if it were 100 turns but on 5 layers (hence the length one fifth of the previously mentioned one)?ThanksRick

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: November 22, 2019, 01:17:23 am
content: I'd just use FEMM, free to download.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 22, 2019, 02:47:09 am
content: The formulas you're seeing are for the infinite solenoid, which doesn't help much.Try:https://paginas.fe.up.pt/~ee08173/wp-content/uploads/2014/03/finite-solenoid.pdfLooks like the axial solution avoids scary integrals and simplifies to an Excel-able formula. Note, the brackets-sub/superscript notation I believe is saying you need to take the difference of the expression evaluated at the two values of ξ (and ξ is given elsewhere).For a flat field over a region of space (i.e., dB/dx --> 0, and higher derivatives and other axes if possible), consider Helmholtz coils. There are at least two well-known cases (2 and 4 loops, giving 1st and 2nd derivatives, respectively). This will be much flatter than a solenoid.You could also -- since this is a symbolic solution, take the derivative, and put two solenoids together such that their derivatives exactly cancel at the point of interest. Making a Helmholtz coil with finite length loops. May allow higher flux density for a given amount of wire and power dissipation?I suppose ideally you'd want to integrate over a range ofras well, to get a range of radii, modeling a finite thickness solenoid -- a multilayer one, perhaps.But yeah, things quickly get complicated in that direction, and you'll find it very attractive to get more tools, or simply model everything in the first place. You might pick up Maxima to automate symbolic math. You can perform a numerical integration in Excel by entering the formula across a large enough array of cells, and summing their results -- Riemann summation. Or, learn FEMM, as mentioned.Tim