hybridfree/eevblog-posts huggingface dataset:
over current protection - Page 1
Forum section: electronics / projects

author: alireza7
author_rank: Regular Contributor
timestamp: December 14, 2017, 05:27:32 pm
content: hii have a electric dc motor which draw 0.3a in normal operation and i want to protect it and make it off when it draws 0.5a .my idea is measure the current and read it by a microcontroller but i don't know how to measure current with low series resistance.how can i do this? can you suggest me any ic?i'm not sure but i think the ic's which measure current by hall effect would be more appropriate than using a shunt resistor ,what do you think?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 14, 2017, 08:16:27 pm
content: Here's a really old circuit I drew, for about that sort of thing:Tim

author: suicidaleggroll
author_rank: Super Contributor
timestamp: December 14, 2017, 09:26:59 pm
content: Quote from: alireza7 on December 14, 2017, 05:27:32 pmWhy would hall effect be more appropriate? This seems like a perfect application of a shunt resistor and a current amp. I have a lot of experience with the LMP8480, but there are tons of options there. 2.5V ADC range with a 60x gain amp and 1A current limit would use a ~40mR shunt resistor, which under normal use would only drop 12mV and burn off ~0.4mW. Feed the output of the current amp to an analog comparator along with your MCU's ADC, and feed the comparator output to an interrupt-capable pin on your microcontroller. Interrupt fires and you shut off the load, end-to-end reaction time should be single digit microseconds if you use a relatively quick comparator and sufficiently high bandwidth current sense amp.
Over-hauling the DSE PSU - Page 1
Forum section: electronics / projects

author: Harvs
author_rank: Super Contributor
timestamp: September 04, 2013, 11:59:13 pm
content: http://www.manson.com.hk/products/detail/42Some time ago I picked up a couple of these very cheap when Dick Smith decided to get out of the business. However, as noted on this forum, they're pretty horrible things. Internally there's very little to them, a transformer, tap changing relay, two MJ15003 series pass transistors, an op-amp and a small handful of discrete components.A thread on here the other day was talking about using a power amp IC as a linear supply, so that got me thinking since I have half a dozen LM3886's doing nothing. Could make a nice conversion to a programmable PSU, and since there's got to be thousands of these PSUs out there, it's probably make a nice open-hardware project.With one of the power supplies torn down, it's evident how easily most of the main parts can be re-used. The tap changing and rectifier is on a seperate PCB, the heat-sink with all it's mounting etc will be perfect. It's also got a plethora of secondaries off the main transformer, so having separate rails for the op-amps and digital circuitry is a snap. No need to touch any of the main wiring.So I set up an LM3886 in the standard application circuit but with all the DC blocking components removed, and a closed loop gain of 20 (the LM3886 is unstable at Gcl<10). I've done a fair bit of mucking around with this setup to familiarise myself with the behaviour of the IC. Overall it's fairly well behaved, however as can be expected with an audio amp IC, it has quite a wide bandwidth and conditional stability, which make it reasonably easy to turn into an oscillator. Some further compensation will be required. However, I've tried driving quite large capacitive loads and there's no hint of that unsettling it. So at least it appears to be a winner, to make best use of the heatsink two of them would be paralleled.So the question now is what to do about it being able to source and sink power? The transformer has only one high current winding (with a CT), and the LM3886 still requires a significant negative bias supply (~>10V) otherwise it goes tits up. So the negative rail of the IC is currently run off a low current -15V rail. This works fine for sourcing current, but the moment it tries to sink any real current, it's going to pull everything out of whack. My thoughts at the moment are to set-up the current limiting circuit to be a window arrangement, with adjustable current sourcing (0-2.5A) and fixed current sink of just 100mA, which will stop it from killing the -15V rail.Thoughts?
over specifying a common mode choke? (current) - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: September 27, 2014, 06:32:54 pm
content: How much % over-rating should be given to a common mode mains filtering choke maximum current?

author: SeanB
author_rank: Super Contributor
timestamp: September 27, 2014, 06:41:19 pm
content: Whatever the fuse rating is, and go one size up. It will run cooler. Those ratings given in the spec sheet are always going to be optimistic, so it pays to overrate the filter. If it is less than 5A use a 6A one anyway, there is little difference going below this.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 27, 2014, 11:16:37 pm
content: If you mean by dynamics, it probably won't make a difference. It's a thermal thing.Beware that some parts may be sensitive to differential current anyway. Multi-aperture cores come to mind (Laird makes these ferrite-block 'array' chokes, which are probably sensitive in this way). Toroids are / should be, too, but I don't know how to estimate by how much; probably little enough not to worry.Tim
Overclocking an ADC / DAC - Page 1
Forum section: electronics / projects

author: BiOzZ
author_rank: Regular Contributor
timestamp: April 16, 2013, 07:03:03 pm
content: I hear quite often products using "overclocked" ADCs and DACsim guessing there SPI ADCs and DACs but what are the risks involved? a few skipped samples?how are the maximum speeds calculated? are they undershot by allot?how fast can you run these things?i was always taught to find a component with 2X the specs you need not 0.5x XPi could see this being very useful

author: smashedProton
author_rank: Frequent Contributor
timestamp: April 16, 2013, 07:12:04 pm
content: To add to this, how are they overclocked? Is it just a simple matter of getting a faster crystal? Or would that mess up the spi

author: SeanB
author_rank: Super Contributor
timestamp: April 16, 2013, 07:32:38 pm
content: Faster clock, and then the other end has to be faster to match. Leads to less accuracy on an ADC and higher noise, along with increased power consumption and heat. Relies on the manufacturer being conservative with the specs, and that almost all devices are able to operate at higher clock speeds, the specs being a guaranteed minimum. Of course some may noy be capable of doing so, so you will need to either select by testing before assembly or test when assembling and grade accordingly to a specific speed grade.

author: BiOzZ
author_rank: Regular Contributor
timestamp: April 16, 2013, 08:54:22 pm
content: i grabbed a MCP3008 8 channel ADC and overclocked it to 6mhz with an mbed (adc was running off 5V) and i see no noticeable change in a 10khz DC offset sine wave from my scope! (when saved as a CSV than opened in excel compared to my scopes CSV)at 3mhz the sine wave is choppyi want to see how high i can push this thing and maybe stick it in a case with an USB to SPI storage bridge for an 8 channel general purpose ADC for 4 channel (psudo) differential pair ADCfunzies!

author: nctnico
author_rank: Super Contributor
timestamp: April 16, 2013, 09:13:27 pm
content: I guess nobody has read up on sample & hold and clock jitter.
Overcoming Burden Voltage - Page 1
Forum section: electronics / projects

author: PiMaker
author_rank: Newbie
timestamp: November 05, 2012, 06:58:31 pm
content: Hello,I think I have a problem with my meter's burden voltage. I have to log current ranging from 1mA-3A but my circuit seems like it is being starved for voltage (works fine without the meter). If I put a voltage regulator on the output of the meter to ensure I get the voltage I need, then use that voltage to drive the circuit, will that work? Do you see any issues in doing that? I guess the better question is, is there a better solution? I've tried to find a meter that has a low enough burden voltage but couldn't find anything for that range.Voltage range is 3.3-4.2V. Datasheet for the meter says burden voltage for the 10A setting is 0.6V.I'm also wondering about when they specify burden voltage. Some datasheets say mV/mA while others just mention the voltage. When they just mention the voltage, is that the total voltage or V/A?Thanks

author: IanB
author_rank: Super Contributor
timestamp: November 05, 2012, 09:23:41 pm
content: Ignore burden voltage for the moment.When placed in a current range, every meter will have a fixed resistance between the terminals. This resistance will depend on the range setting, being very low on the 10 A range and progressively greater on mA and uA ranges. You can measure this resistance using another meter on the ohms setting and therefore find out how much this series resistance is likely to affect your circuit if you insert the meter to measure current.Secondly, when on the 10 A range you may find that the probe leads themselves add significant resistance to the circuit, especially if they are low quality leads.Normally speaking, if an inserted DMM on the 10 A range stops your circuit from working, your circuit has a problem.

author: ModemHead
author_rank: Frequent Contributor
timestamp: November 05, 2012, 11:18:17 pm
content: I would guess that if the burden voltage is specified as V and not V/A, then it is for full-scale reading, ie. 0.6V/10A = 0.06R

author: PiMaker
author_rank: Newbie
timestamp: November 05, 2012, 11:54:34 pm
content: Thanks, Ian. I think I was chasing down a rabbit hole. Your comment about low quality leads got me thinking. I'm using some leads that were around the lab and look worse for the wear. I replaced them with some good quality leads and everything worked fine. Sometimes things are a lot simpler than what we think!That makes perfect sense, ModemHead.Thanks again.
overkill pikcup combination - Page 1
Forum section: electronics / projects

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: October 21, 2019, 01:14:26 pm
content: I found out that whit 3 pickups (5 single coils in this case) you can have an abundance of combinations, somewhere around 1000 I guessso I built this circuit whit as many switches and combinations as I could stand...so here it is you can use it if you're crazy!https://easyeda.com/evalc2636/all-config-pickups

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 21, 2019, 01:36:04 pm
content: Alright, so don't forget to post some sound clips when you're done building that. I'm not sure all combinations will really sound different enough to justify this, but hey, why not.
Overkill Solar Battery/USB Charger (LTC3130 & LTC3539 based) - Page 1
Forum section: electronics / projects

author: ANTALIFE
author_rank: Frequent Contributor
timestamp: September 27, 2017, 01:16:46 pm
content: So here is a solar battery/usb charger I made using LTC3130 & LTC3539. It's a bit overkill in the sense that the components I picked are a bit too good (Linear Technology IC's, super low resistance inductors & polymer electrolytic capacitors), but at least I managed to get ~85% & ~90% peak efficiency for Solar-DC & DC-DC stages.Full write up & project fileshere(with heaps more pictures) for those interested.Most surprising thing I found was that LTspice was understating performance for the LTC3130 (Solar-DC converter).
overkill tea timer (turns heater off) - Page 1
Forum section: electronics / projects

author: grifftech
author_rank: Frequent Contributor
timestamp: February 22, 2018, 08:26:46 pm
content: What do you think? is it ok to connect a contactor like this?

author: Ian.M
author_rank: Super Contributor
timestamp: February 22, 2018, 09:25:51 pm
content: Looks like gratuitous overkill. If its a 40A contactor with a 15A load, why would you parallel the contacts?Personally, I'd switch Line and Neutral, leaving one contact spare.Also, what's going on with the over-complex MCU power and contactor control circuit?What's the contactor coil voltage and current and is its coil DC rated? Assuming its AC rated, If it uses a low voltage, then you can probably use a sensitive gate TRIAC driven by the MCU to control it, and unless the MCU needs a lot of current from its 5V rail, half wave rectify the control transformer secondary then regulate that down to 5V to supply the MCU. If it needs lots of 5V current, you'll need a bridge rectifier and a buck converter to get the 5V, and an opto-TRIAC between the MCU and the TRIAC. If its DC rated, go with a bridge rectifier to feed the regulator or buck converter for the 5V coil, and a logic level MOSFET to switch the raw DC to the coil.

author: drussell
author_rank: Super Contributor
timestamp: February 22, 2018, 09:26:59 pm
content: Wait, you're using 120A of contact to switch <15A of juice?
Overkill with four diodes? - Page 1
Forum section: electronics / projects

author: ElectricPower
author_rank: Frequent Contributor
timestamp: December 11, 2022, 10:11:55 pm
content: I have made an circuit (WLED Controller). This is an amateur version of the DIG-Uno.The circuit works fine. I have ordered the board and attached LEDS and microcontroller, so no problem with the board.But i just wonder if it is overkill with use of four diodes?I have four SS24 SMD diodes on the board. Can i just use two?Her is my working schematic:

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: December 12, 2022, 01:57:21 am
content: I'm not sure what those diodes are supposed to do?

author: inse
author_rank: Super Contributor
timestamp: December 12, 2022, 11:58:38 am
content: They can provide protection against reversed power supply, but only the ones after the fuse make sense.Also the fuse should be directly at the input.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: December 12, 2022, 12:04:56 pm
content: It's a lot of parts to provide a not so great function. What's wrong with the typical P-MOSFET reverse polarity protection? Or a resettable fuse? Or a three-pin connector that can plug either way?

author: ElectricPower
author_rank: Frequent Contributor
timestamp: December 17, 2022, 01:02:00 am
content: Thanks for replyPlease read about Dig-Uno. My circuit is an amateur version of that. See here:https://quinled.info/pre-assembled-quinled-dig-uno/
overkill ~15w amp design. - Page 1
Forum section: electronics / projects

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: January 24, 2020, 08:01:17 pm
content: I just had some fun trying new things in this shematic and just messed arround.it's kinda a copy of the Mesa Double Caliber, but changed a LOT.and with 2 6p14p(EL84) tube SE outputhttps://easyeda.com/evalc2636/685685856856also yes, it's really messy, also the part numbering is messed up cause I was doing a lot of other things in that schematic before and it messed it up.
Overvoltage due to LC ringing at input filter of power factor corrected SMPS - Page 1
Forum section: electronics / projects

author: ocset
author_rank: Super Contributor
timestamp: September 23, 2017, 07:34:11 pm
content: Hello,Offline, single stage, Power factor corrected LED drivers do not have much capacitance at their input (for obvious reasons).In order to get good filtration with such small filter capacitance, they have to use inductors [] with the capacitors to make LC filtration.Of course, when you have an LC circuit and little capacitance, the voltage at the filter output can ring up to very high voltages and cause damage (specially when the product is switched ON at the peak of the mains)……hence protection circuitry must be added in to mitigate this.The best way to mitigate this, would you agree, is to use a current clamp just upstream of the LC filter….. do you agree?Why is the following “current clamp” method (as attached) so rarely seen in designs and App Notes?In order to protect the LED driver from mains transients, we wish to use a SMCJ400A TVS. Which side of the LC filter should we best place the TVS?LTspice sim and a schem attached.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 23, 2017, 07:56:24 pm
content: There can be no filter that is not terminated with resistance. If you think you've made one without resistance, nah, it's found that resistance, somewhere. It may not be the resistance you had hoped for.What do you expect?Not having a LISN model for the mains seems a pretty big omission.Damping can always be added with an R+C or R||L pair, or a lossy component that is equivalent to these.Tim

author: ocset
author_rank: Super Contributor
timestamp: September 23, 2017, 09:16:58 pm
content: Thanks, do you think i need to add an RC damper at the output of the filter? (=input to the led driver).All we are worried about is avoiding overvoltage at switch on.............or during mains transient.
Overvoltage protection design - Page 1
Forum section: electronics / projects

author: mitrynicolae
author_rank: Contributor
timestamp: December 27, 2018, 10:08:13 pm
content: Hi,I need your assistance in designing a robust overvoltage protection. The circuit must respect the following conditions:1. low current consumption < 100uA when the over voltage protection is triggered2. very low or no current consumption (if possible) if the over voltage protection is not triggered3. the protection should be able to shelf recover4. the output waveform should not be distorted in any way, except the case when the protection is on. This is the only case in which the output can be trimmed to the ovp value.5. if possible the voltage level of the ovp should be adjustable.6. no specialized IC's are allowed. Only basic components like transistors, diodes (of any kind), resistors, capacitors and so on. If possible also avoid op amps.7. if any supply voltage will be required to power the ovp then this voltage will be 5 volts exactly. No 3.3v supplies or above 5 volt supplies are allowed.Thank you all for your time and Merry Christmas!!!

author: bson
author_rank: Unknown
timestamp: December 28, 2018, 03:22:54 am
content: Looks like you're looking for a 4 quadrant supply?
own build 3D printer - Page 1
Forum section: electronics / projects

author: akis
author_rank: Frequent Contributor
timestamp: May 09, 2017, 07:21:36 pm
content: I vaguely remember there was some open source (?) project to design/create/build your own 3D printer. Could someone please suggest the project?

author: akis
author_rank: Frequent Contributor
timestamp: May 09, 2017, 07:25:25 pm
content: ahh, it's reprap I think!

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 09, 2017, 08:09:05 pm
content: joint the clubhttp://forums.reprap.org/and you'll have lesser and lesser time than you can imagine...

author: akis
author_rank: Frequent Contributor
timestamp: May 10, 2017, 08:08:43 am
content: Sounds like a lot of work though? As a parallel imagine if your Laser Scanner/Copier/Printer from Amazon arrived in bits and you'd have to put it all together including controllers for the lasers, the mirrors, the sheet feeders, then write the software for those MCUs etc

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 10, 2017, 12:38:14 pm
content: if you are not familiar, just buy this and learn from it...http://www.ebay.com.my/itm/Tronxy-Upgraded-DIY-3D-Printer-High-Precision-Reprap-Prusa-i3-Free-Shipping-8GB-/322426940695?hash=item4b1224ad17:g:nZEAAOSwCU1Yp5d4will save you lots of time...ymmv...

author: Zinger
author_rank: Contributor
timestamp: May 10, 2017, 01:04:53 pm
content: My local MakerSpace has several slightly modified Prusa I3 printers. Nice machines, solid and good print quality.http://shop.prusa3d.com/en/3d-printers/59-original-prusa-i3-mk2-kit.html

author: akis
author_rank: Frequent Contributor
timestamp: May 10, 2017, 02:13:33 pm
content: This one for example?http://www.ebay.co.uk/itm/2017-Upgraded-Full-Quality-High-Precision-Reprap-Prusa-i3-DIY-3d-Printer/352032578491?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D43783%26meid%3D538878c580eb4a47a6f835b614f654e2%26pid%3D100005%26rk%3D6%26rkt%3D6%26sd%3D132140385763
P-channel JFET as switch - Page 1
Forum section: electronics / projects

author: sadboi
author_rank: Newbie
timestamp: December 08, 2023, 04:52:08 am
content: Hi,I am trying to use p-channel JFET as a switch that is normally closed when the circuit is unpowered.I'm simulating the the SST177(datasheet here)in LTSpice, which has Id=10nA when Vgs(off)=2.25V. I am seeing the circuit conduct when Vgs=0, however when the voltage increases to above 2.25V it still conducts significant current.Is the simulation model wrong or am I completely wrong about how JFETs work? I've attached the spice circuit and plots.

author: ledtester
author_rank: Super Contributor
timestamp: December 08, 2023, 06:17:24 am
content: From this video:WORKING OF P CHANNEL JFET | SEMICONDUCTOR DEVICES | PART NO 34https://youtu.be/gpRKP907VpMV_GS is positive and the drain-source voltage is usually negative - i.e. the source is more positive than the drain. This would mean reversing V5 in your schematic.

author: Kleinstein
author_rank: Super Contributor
timestamp: December 08, 2023, 09:17:36 am
content: The JFETs are symmetric and drain and source are exchangable. The one with the more positive voltage gets to function of source. So the FET is not working in a source circuit as a kind of switch, but more like a source follower.

author: magic
author_rank: Super Contributor
timestamp: December 08, 2023, 09:41:45 am
content: In short, the gate has to be (sufficiently) reverse biased with respect to both remaining terminals to really stop conduction.

author: Zero999
author_rank: Super Contributor
timestamp: December 08, 2023, 05:52:27 pm
content: V6 needs to exceed V5 by 2.5V, so 8.5V, to switch J2 off.
P-Channel MOSFET always on - Page 1
Forum section: electronics / projects

author: Aankur
author_rank: Newbie
timestamp: May 16, 2022, 09:06:07 am
content: HelloI am using a MOSFET driver circuit with SI2303 as p-channel mosfet and SI2302 as n-channel mosfet.I have given control signal (of 5V) on the gate of n-channel mosfet to turn-on and off the p-channel mosfet.However, the p-channel mosfet is not getting off and I am constantly finding voltage on Output (marked as Point-A).Please let me know what is the problem in this circuit.Thanks

author: Zero999
author_rank: Super Contributor
timestamp: May 16, 2022, 10:26:06 am
content: There are three most likely possibilities:1) One or both of the MOSFETs is bad.2) One or both of the MOSFETs is connected backwards.3) Your multimeter is measuring the tiny leakage and it will be fine.

author: VooDust
author_rank: Regular Contributor
timestamp: May 16, 2022, 11:49:05 am
content: to measure this properly, you need to connect a dummy load from your output to ground. You can use a resistor for that.

author: strawberry
author_rank: Super Contributor
timestamp: May 16, 2022, 06:00:09 pm
content: 1uA DS leakage current - 100k resistor = 0.1V + noise0.6Vgs(threshold)
p-mosfet voltage leakage from gate to source - Page 1
Forum section: electronics / projects

author: silas15
author_rank: Newbie
timestamp: February 15, 2020, 10:02:06 am
content: My circuit works on battery or USB power. I want USB to be primary and 4xAA secondary source. When USB is present, batteries are not dichargged. Even batteries are not needed when USB power is present. Schema attached. I uderstand that voltage from USB close P-MOSFET (BSS84). When i plug USB, on mosfet source is voltage (without batteries). It gives about 23mA short to ground. This come from drain! I dont understand why. I measured mosfet with diode test. New mosfet gate to source 0V, on used mosfet gate to source 0,9V. I dont get why is this hapening. Voltages are far below maximum ratings in datasheet.

author: fcb
author_rank: Super Contributor
timestamp: February 15, 2020, 10:43:46 am
content: Circuit looks like it should work out. No gotchas in the data sheet either.Check layout obviously, blown/mislabelled components.Possible try measuring current when gate is tied to source (off).

author: Mr Evil
author_rank: Regular Contributor
timestamp: February 15, 2020, 03:33:01 pm
content: Fully charged alkaline batteries can be up to 1.6V each. USB voltage can be as low as 4.4V and still be in-spec. That means that the MOSFET's Vgs might be as high as(4*1.6)-4.4=2Vwhen USB power is connected. The datasheet for the BSS84 says thatVgs(th)can be as low as 0.8V, so 2V is enough to turn it on.Assuming that's the problem, then a simple solution would be to choose a MOSFET with a higher threshold votlage.

author: silas15
author_rank: Newbie
timestamp: February 15, 2020, 05:01:30 pm
content: Thank you. But I think there is more. When there is no battery (only USB), current goes from gate to source. Multimeter from source to ground showing about 23mA, voltage in open circuit 4,9V. From drain to ground 0mA. That tells me that discharged batteries will be charging.

author: fcb
author_rank: Super Contributor
timestamp: February 15, 2020, 05:48:52 pm
content: Unless the BSS84 is damaged/wrong way round then what you are describing shouldn't happen.
P6KE + fast Silicon clamp is slow? - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: February 09, 2021, 04:19:25 pm
content: The series clamp network does have some effect - but the diodes do not seem to be very fast, or to clamp much. Scope leads directly across the clamp diodes (see image).I used a BYV27-200-TR (fast silicon) in series with a P6KE18A-R0G (Unidirectional 18V TVS). Aside: I was unable to find a so-called "soft recovery" type for the silicon except at high cost.One thing does confuse me - the P6KE data sheet from LittelFuse headlines the fast response• Fast response time: typically less than 1.0ps from 0 Volts to BV minthen shows a response plot inmilli-seconds.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 09, 2021, 05:26:28 pm
content: Show layout.What they are plotting is the waveform used to measure surge capability. I don't know that anyone actually specifies response time, in terms of having a fixture to actually measure it; I think it's just assumed. Rest assured, avalanche breakdownisvery fast -- the limiting factor in circuit, is the path to the diode, not the diode itself. In particular, at these impedances, stray inductance.So, it's very likely that layout is to blame for the lumpy waveforms.Tim

author: Yansi
author_rank: Super Contributor
timestamp: February 09, 2021, 05:38:18 pm
content: Quote from: T3sl4co1l on February 09, 2021, 05:26:28 pmOr simply the probing technique

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 09, 2021, 06:50:27 pm
content: Quote from: Yansi on February 09, 2021, 05:38:18 pmCurrently putting that as second most likely. All the more reason for layout (including probing technique) pics.Tim

author: AndersJ
author_rank: Frequent Contributor
timestamp: February 09, 2021, 07:30:50 pm
content: Could this happen if the FET turn off is slow?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 09, 2021, 07:35:43 pm
content: Also, curious what's on the other side of the transformer, and what thesmall-signal parametersof the transformer are, or its frequency response, or just winding schedule, something. Those waveforms look pretty lumpy at best..Tim

author: 741
author_rank: Frequent Contributor
timestamp: February 10, 2021, 10:40:12 am
content: Thanks for the feedbackI wrongly thought that because the scope was right across the TVS, the layout was not a concernNow I've added a 56uF 0.2R ESR capacitor close to the TVS so as to provide a low-Z path back to Vdd.Success!!
P9823 - Getting Started - Page 1
Forum section: electronics / projects

author: codemonkeyrawks
author_rank: Contributor
timestamp: May 25, 2018, 01:48:38 am
content: Hi There,I am still a newbie a little bit on using shift register led's. I bought some LED's using P9823 (SPI) interface. I was curious if there was some Arduino code to look at rather than use a library like (FastLEDS) that I could get the led working without a bunch of fluff code.I am a little lost on how the timing should be by T0 and T1 and RES and what I should be passing as a signal. The doc is really unclear what the waveform might look like. I can code Arduino code to match up timing.

author: codemonkeyrawks
author_rank: Contributor
timestamp: July 02, 2018, 03:40:57 am
content: I ended up using the Adafruit NeoPixel Library.
Pace mini termojet project - Page 1
Forum section: electronics / projects

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: September 17, 2021, 04:21:16 pm
content: Hi,Today I was given two pace minitermojet handpieces, but I dont own any pace equipment.I was wondering If I can build something to work with, I have a WDM3 from weller and a weller wdm1.Anyone knows what termocouple the handpiece uses? It should be powered with a 21VAC at max 75W

author: perdrix
author_rank: Frequent Contributor
timestamp: September 18, 2021, 06:51:46 pm
content: The old Sensatemp Pace equipment used a PT100 temperature sensor not a thermocouple.Did the later ones use a thermouple?D.
Packaging - Page 1
Forum section: electronics / projects

author: rakeshm55
author_rank: Regular Contributor
timestamp: May 24, 2012, 06:02:04 pm
content: Hi,I have 2 questions to raise regarding packing my system.In one of the project i am working on I use some Custom made PCBs from a third party vendor with mounting holes to fix into a specific box of smaller size (98X98X52mm). Since My project demands a big battery (3.7V , 10Ah Li ion battery pack. 18650) My enclosure size is much bigger (139X119X70mm) whose mounting holes does not match with the smaller box. As a make shift arrangement I fitted the battery and the Electronics(PCB) into the box by first mounting an acrylic sheet to the Big box and mounted the PCB by drilling threads(M4) to the sheet on par with the mounting holes of PCB. screwed tight the PCB to the acrylic base with thread drillled on the sheet.Then used cable ties to fix battery to the sheet. The assembling process is still quite tiring.So I would like to make a "mounting PCB" instead of the acrylic sheet and have some fixture mechanism so that I can screw the PCBS to the plate. How to do this??How can I fix my third party PCB to "mounting PCB" how to Hold them ?? should I use internal-external threaded standoffs or is there other methods so that I can frequently assemble and disassemble the whole thing.My second query is how to fix the battery pack(3 cell 18650) to a plate without cable ties...Please advice

author: SeanB
author_rank: Super Contributor
timestamp: May 24, 2012, 08:44:04 pm
content: Hank fasteners will do a thrteaded insert that will survive frequent use, and will be strong. If ties are a problem then get releasable ties and hold down the battery that way, or use velcro pads to stick the battery down. Self adhesive pads will work well in that case, and the battery will stay put through normal handling, but can be pulled off if it needs to have this done often.

author: rakeshm55
author_rank: Regular Contributor
timestamp: May 25, 2012, 04:56:55 am
content: HiHow to fix hank fastner to the "mounting PCB" or the base plate PCB??? Actually the mounting plate (mounting PCB) will be fixed to Bigger box and the hank fastner need to be fixed on the PCB how to do thid so that my electronics could be screwed to hank fastners.PLease advice.

author: SeanB
author_rank: Super Contributor
timestamp: May 25, 2012, 03:03:35 pm
content: you buy the inserts, a setting tool ( looks like a hand rivet gun) and a mandrel for the size you are using. Drill the appropriate hole in the panel, screw the insert to the mandrel, place in hole and squeeze the handles together. Unscrew mandrel and you are done.
Packing transformer core plates. - Page 1
Forum section: electronics / projects

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: October 02, 2022, 06:13:49 pm
content: what is the most efficient/fastest way to build an EI core around a bobbin? and how is it done in automated manufacture?and can anyone link some documentation on the comparison of core types (C core vs EI core for example)?and a random question, was the paper insulation on old transformers yellow from the beginning? I know paper yellows over time but I've never seen even a picture of an old transformer with white wrapping.

author: jonpaul
author_rank: Super Contributor
timestamp: October 02, 2022, 08:18:18 pm
content: laminations are stacked with a laminating machinepossible prototype short run by handlaminations are supplied with insulation on surfacecontact the laminations steel manufacturers for specs and proceeduresAfter assembly, lam stack is held by screws, bracket or varnish impregnatedjon

author: mag_therm
author_rank: Frequent Contributor
timestamp: October 02, 2022, 09:31:32 pm
content: When search "kraft transformer insulation" > images will show lots of photos of transformers with new insulation before impregnation.In the old days of hand stacking, the lams were often not individually stacked opposite handed.They did it "3 in hand" etc to save time. It was a tedious job.So if you look at an old transformer near the ends of the E, you will see the number of lams across the gap.That increased I mag a bit compared to piece by piece stacking in machine.In the larger transformers, there were two sets of lam packs (of different dimensions) laid alternately to distribute the gaps.Of course, in a gapped core, like a DC choke, the lams are all in same orientation.

author: jonpaul
author_rank: Super Contributor
timestamp: October 04, 2022, 05:22:33 am
content: gapped center lamps available on special order, cutting is not practicalsimple paper gaps are fine for 99% od useany mains transformer will be noisy if not varnishedJon
PAE in saturation with RF amplifier device - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: January 26, 2025, 03:49:29 pm
content: Hello,In the datasheet below we have PAE value(formula below) and saturation point(they dont say if its P1dB)What are the maximal Pin and Power at the maximal P1dB saturation point?https://www.qorvo.com/products/d/da004195

author: mtwieg
author_rank: Frequent Contributor
timestamp: January 26, 2025, 08:37:22 pm
content: The Pout vs Pin figure on page 6 should have your answer.It's true they don't explain exactly what defines "saturated" output power. I'm guessing it's the point where output power drops below 1dB of peak output power (rather than peak gain).

author: john23
author_rank: Frequent Contributor
timestamp: January 26, 2025, 10:16:16 pm
content: Hello ,I am working at 9GHz,suppose PAE=30%=0.3,I need to know the PIN Pout and Pdc.How can I know the situion of PIN POUT and PDC in saturation?Thanks.https://www.qorvo.com/products/d/da004195
Painful goof LF353? - Page 1
Forum section: electronics / projects

author: w3amd
author_rank: Regular Contributor
timestamp: December 23, 2015, 10:28:00 pm
content: Hi guys,I have a problem on a PCB. Something is clamping the +12V and -12V supply rails to +/- 1V on one PCB and about +/-0.6V on another. So I'm walking through the design and I may have misread a datasheet and I'm looking for a second opinion.Datasheet link:http://www.st.com/web/en/resource/technical/document/datasheet/CD00000454.pdfTable 1: VCC Supply Voltage +/- 18V (1)And Note 1 is: All voltage values, except differential voltage, are with respect to the zero reference level (ground) of the supply voltageswhere the zero reference level is the midpoint between VCC+ and VCC-.I think what I have is okay based on this datasheet. I think they mean differential voltage are the input pins for this note.Am I correct?TIA

author: Marco
author_rank: Super Contributor
timestamp: December 23, 2015, 10:34:53 pm
content: Well you made a painful goof somewhere, but the opamp can indeed take 36V.Just give it enough current and whatever is pulling down the rails will show itself

author: w3amd
author_rank: Regular Contributor
timestamp: December 23, 2015, 10:40:56 pm
content: Haha yes Marco. This board has some 36 op amps in total. The board wants 660 mW total and idling it really shouldn't pull anything. The switching supply for +/- 12V is limited to 2W.So far the footprints appear to be okay (nothing is backward etc.) but the one board with 660 mV tells me some diodes are doing some protective clamping somewhere.Thanks!

author: MickM
author_rank: Regular Contributor
timestamp: December 23, 2015, 11:49:13 pm
content: Hi;can you break the supply line halfway?Something that bad should show on an Ohm meter.Old school "divide and conquer".Keep cutting until something changes.Or a very sensitive millivoltmeter should show where the current is going.Have you placed your hand down flat on the board to find hot chips?Mick M

author: w3amd
author_rank: Regular Contributor
timestamp: December 24, 2015, 12:55:55 am
content: Unfortunately, it goes right to the power planes on an inner layer of the board and all nets are direct. No heat at all. So far I haven't found any problems with any of the footprints.JohnW3AMD

author: Richard Head
author_rank: Frequent Contributor
timestamp: December 24, 2015, 08:08:04 am
content: Try limiting the supply current to perhaps 250mA and then give it time to warm up. Feel each device with a finger (or thermal camera if you have!) until you've located the culprit.I've also used the voltage drop method with a precision voltmeter. Not always practical though.I was surprised by how much current a microscopic copper flash can take.
Panasonic Ni-Cd battery charger for repair - Page 1
Forum section: electronics / projects

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: March 15, 2021, 10:34:27 am
content: Hi There,I got a part of vacuam cleaner machine driven by DC charger. May be it was manufactured in 2018.User might through it away because it was troubling.9 pcs of P-130SCS 1.2V 1300mAh has joined togeter to get 1.2×9 Vdc.https://www.digikey.in/product-detail/en/panasonic-bsg/P-130SCS-A06/P162-ND/530492Basically it was using for drive a 9 v DC motor. Manufacturer recommended to plug it with 9V/300mA charger for use it 8 hrs, may be charging time was for 15 mins.1. Does it risky to use this battery after a long time?2.It may damaged?3. How can I charge it with another way?4. Take a look the charging and discharing circuit and battery bundle.Recommend me any safe mode charing topology or particular circuit.Hope you will help.

author: t1d
author_rank: Super Contributor
timestamp: March 15, 2021, 09:37:01 pm
content: Hi! Let us make sure that I understand your questions.1) You have come to have a 9V battery pack.2) You want to make use of it for projects other than what it was manufactured to do.3) You are wondering if it is safe to use.4) You also need a way to charge it.Correct?If so, we need just a little more information to be able to help you...What method do you want to use to answer the questions above? Meaning, do you want to build a solution, or buy a solution. Your desires will direct our path.If you want to build a solution, what resources do you have? Electronic knowledge and equipment... Multimeter, soldering iron, etc. What other power sources do you have that we might use, or adapt?For testing the battery pack, we can use very basic methods, or fancy equipment. The basic approach would be to do some math, employ a resistor that would drain the battery slowly, under a very light load and see how long it takes to reach maybe 3 volts (being 1/3 of 9 volts.) If you have a DC constant current electronic load, you could use that, of course.For charging the battery pack, you need a power source... A variable power supply made for electronics testing, or a charger for some other piece of electronics.Here is one thing to know about these types of battery packs. Even if they test as bad, they still may have some life in them... Meaning, it is very typical for the first battery in the series to fail first. This makes the unit appear to be completely bad, but, in fact, the batteries after the first may still have some life in them. The first battery might be replaced, or the remaining good batteries might be used for other purposes. YouTube has lots of good videos on repairing battery packs. But, you are correct to start with testing.Please answer the questions and we will move one to acquiring a solution.
Panasonic QE-QL103 USB Power Bank - Page 1
Forum section: electronics / projects

author: dexters_lab
author_rank: Unknown
timestamp: May 09, 2015, 09:07:28 am
content: I picked up two types of USB power bank when i was in Japan last year, the QE-QL103 (2900mah 1A) and a QE-PL203 (5800mah 1.5A & Qi Charging), the other day i was curious enough to break open the smaller of the two as i wanted to see how these branded, Japanese made power banks compare to the Chinese stuff you find on ebay.the QE-QL103 costs about £12 from Yodobashi, so is not an expensive item considering it will have a good quality Panasonic 18650 cell inside.http://www.yodobashi.com/%E3%83%91%E3%83%8A%E3%82%BD%E3%83%8B%E3%83%83%E3%82%AF-PANASONIC-QE-QL103-K-USB%E3%83%A2%E3%83%90%E3%82%A4%E3%83%AB%E9%9B%BB%E6%BA%90-2900mAh-USB%E5%87%BA%E5%8A%9B%EF%BC%9A1%E3%83%9D%E3%83%BC%E3%83%88-%E6%9C%80%E5%A4%A7%EF%BC%9A1A/pd/100000001001763317/There is micro USB for charging and a standard USB for output to devices, handily it also includes a removable micro USB adaptor that can aid charging and connecting to your micro USB devices.It was a bit of a struggle to open, i had thought it might have been ultrasonically welded but it actually has a screw and clips.I was surprised by the complexity of the controller board inside, containing an Atmel XMega16D4http://www.atmel.com/devices/atxmega16d4.aspx?tab=overviewThe battery and board are soldered together looping through a plastic carrier so i can only get pics of one side of the board, i did consider de-soldering the batter to see the other side but i wondered if it might not power back up when reconnected (i use this charger every day!). The battery also has a temperature sensor glued to it.One thing i did do was measure the battery voltage. It turns off at about 2.6v and charges upto 4.3v so they are really pushing the max out of the cell. One thing i did notice is it seems to not draw power out of the cell all the time, when powered on and supplying power to a USB device i saw the battery voltage dropping in steps so looks like they are drawing power from the cell in pulses.If people are interested i could bridge the battery terminals so i can remove the plastic carrier without disconnecting the battery and get a view of the other side of the board and do some more in depth poking around?
Panavise available in europe: Mouser - Page 1
Forum section: electronics / projects

author: BurnedResistor
author_rank: Regular Contributor
timestamp: July 12, 2017, 09:07:59 pm
content: Hey all,Just though I would drop this buy:Was looking to buy some panavise stuff in europe, and everything seemed unusually expensive (amazon,ebay, resellerrs). But mouser Has all panavise products and accesories at a price very close to what the official website lists.If you are looking for panavise in europe, check it out!http://www.mouser.at/Panavise/Tools-Supplies/Tools/_/N-5gg6?P=1z11yuc
Panel mount 18650 battery holder - Page 1
Forum section: electronics / projects

author: FenTiger
author_rank: Regular Contributor
timestamp: November 27, 2019, 12:13:43 am
content: This is a panel mount AA battery holder.I've been searching for a similar panel mount 18650 battery holder, but haven't been able to find one.Does anyone know where I might obtain such a thing?All the 18650 holders I can find are open to the elements; either it's on the outside, exposing the battery to whatever else is in the bag around it, or it's on the inside, and the device has to be dismantled to change the battery.

author: daniel444
author_rank: Regular Contributor
timestamp: November 27, 2019, 12:57:46 am
content: i have also been searching for a waterproof modular holderwhat about this "VRUZEND" holder i have not used them myself but i looks like it would seal around the open end partlooks like there is a minimum order of 100$ , probably why i have yet to buy some
Panel mount project box? - Page 1
Forum section: electronics / projects

author: miceuz
author_rank: Frequent Contributor
timestamp: April 27, 2017, 02:42:15 pm
content: I'm building an instrument that will be mount in the panel. Can someone point me to a source of project boxes designed for this purpose? So that cover is bigger than the body to cover all the gaps between the body and the panel. I can't find such category in online distributor catalogs.

author: jct
author_rank: Contributor
timestamp: April 28, 2017, 06:04:52 am
content: Don't know where you are situated, but these guys have distributors worldwide:http://eng.italtronic.com/products/panel_mounting_enclosures/

author: miceuz
author_rank: Frequent Contributor
timestamp: April 28, 2017, 08:33:31 am
content: Thanks a lot! I'm from Lithuania, no distributors here, bu I will try to look around.
Panel mount trimmer / screw driver guide - plastic part. Where to get? - Page 1
Forum section: electronics / projects

author: DTJ
author_rank: Super Contributor
timestamp: April 11, 2023, 01:12:14 pm
content: We've got a tact switch too far back behind a panel, about 20mm, and are worried about users pushing a screw driver in and shorting out things around the switch.We can't get a SMT long actuator tact switch to suit. Extending the actuator is messy.We thought something like a trimmer / screwdriver guide might exist.A plastic thing that would push into a round hole on the front panel and have a tube going back that would guide a small screwdriver back to the tact switch actuator would be ideal.Perhaps something like a push in LED panel bezel but longer.I had a look at Keystone and found nothing.Any other ideas?Cheers

author: jpanhalt
author_rank: Super Contributor
timestamp: April 11, 2023, 01:29:30 pm
content: Shoulder washers can be had that are fairly long:https://www.mcmaster.com/products/shoulder-washers/A press fit in the panel might not be durable enough, but gluing a sleeve on the back might be enough.

author: DTJ
author_rank: Super Contributor
timestamp: April 11, 2023, 01:41:00 pm
content: Quote from: jpanhalt on April 11, 2023, 01:29:30 pmThanks - that might well be a viable option.
Panel mounted test points? - Page 1
Forum section: electronics / projects

author: AndyC_772
author_rank: Super Contributor
timestamp: December 11, 2018, 02:15:57 pm
content: HiI have a prototype PCB which I want to put inside a metal box for shielding and protection, but it has a few signals on it which I need to probe with a scope from time to time.I'm looking for a panel mounted test point, which is insulated from the chassis, and to which I can clip a scope probe. (Basically, the same kind of thing that is used to provide the calibration signal on a scope's front panel).Panel mounted sockets are easy to come by, but protruding pins or loops seem much less common - to the extent that the nearest I can come up with is to use a small socket and actually solder a PCB test point into it. That's ugly, though.Can anyone please suggest a source for suitable test points? Thanks!

author: coppercone2
author_rank: Super Contributor
timestamp: December 11, 2018, 03:25:07 pm
content: search for something like an isolated turret connector.Of interest also may be probe adapters (where you stick a multimeter prove into a isolated machine pin but obviously only for DCish).

author: LapTop006
author_rank: Unknown
timestamp: December 12, 2018, 05:33:04 am
content: When I've had products with this need in the past they've universally used SMA/SMB/SMC (depending on density needs mainly) sockets on the panel (sometimes behind a cover). Especially by the time you're down to SMC the pitch is denser than usable with individual pins.Two other options would be micro-coax array connectors (probably too expensive), and just using a standard 0.1" pin header set for IDC cables if the frequency is low enough.