hybridfree/eevblog-posts huggingface dataset:
Strange filter response - Page 1
Forum section: electronics / beginners

author: Seán
author_rank: Contributor
timestamp: June 09, 2018, 04:12:45 pm
content: Hello,I have a question about an op-amp filter response. My filter is a multiple feedback filter with a gain of 30 V/V and a cutoff of around 10kHz.What, if anything could result in a flat passband response at say 30 dB up to about 5kHz, which then drops to about 25 dB staying flat at the level up to around 10kHz, given that the response should be flat at 30 dB? It seems to have a double dip.I have heard people say that the component sizes can cause issues in designs? In the sense that you should use kOhms instead of hundreds of Ohms for resistors and so on. But I am not sure what impact this could have, if any.Thanks in advance for any thoughts or suggestions.Seán

author: rstofer
author_rank: Super Contributor
timestamp: June 09, 2018, 09:11:45 pm
content: A schematic would help.Are you running up against the gain-bandwidth product of the op amp? Check the datasheet.

author: Seán
author_rank: Contributor
timestamp: June 09, 2018, 09:36:39 pm
content: Quote from: rstofer on June 09, 2018, 09:11:45 pmHi,I put a picture of the schematic in the original question. The simulated response looks fine, the measured response seems to have the issue.The gain bandwidth of the op-amp is 5.5MHz, so I don't think that is the issue?Thanks,Seán

author: bson
author_rank: Unknown
timestamp: June 10, 2018, 08:49:31 am
content: Your component values would indicate a gain of 3 rather than 30.When I calculate it I get about 36ohm, not 360ohm for R1 and R4 given an R2 of 1.1k, gain of 30, w0 at 2*pi*10kHz and Q=0.707. (Actually 35.4 and 36.6 for the resistors.) I also get 630nF for C1 and 10.2nF for C2; again your values would suggest a gain of 3.MFB/Rauch filters aren't that sensitive to component tolerances and values, so I doubt that's the problem.At an actual gain of 30x youmightbe pushing the envelope on phase margin and introducing oscillation...

author: Seán
author_rank: Contributor
timestamp: June 10, 2018, 09:42:05 am
content: Isn't the gain set by -R2/R1, so 11k/360 = 30.5.

author: bson
author_rank: Unknown
timestamp: June 10, 2018, 10:17:07 pm
content: Oh, it's 11k? It looked like 1.1k to me. I guess one of the grid dots lined up with the value. That makes more sense.
Strange inverter behaviour; what am I missing? - Page 1
Forum section: electronics / beginners

author: aeberbach
author_rank: Regular Contributor
timestamp: August 01, 2024, 12:12:36 am
content: I'm trying to use a dual inverterhttps://www.ti.com/lit/ds/symlink/sn74lvc2gu04.pdf?ts=1722469526037&ref_url=https%253A%252F%252Fwww.google.com%252Fto power one of two LEDs based on the output of a caps lock LED from an old Amiga computer. Attachment shows the circuit.The existing NPN transistor drives the caps lock LED in the original keyboard. Its base is the output of the 6507 keyboard controller (a variant of 6502) reflecting the state of caps lock. Low is lit, high is unlit, as the LED in the original keyboard has VCC on the other side.What I want to do is not use the original LED, instead use that state as the input to the inverter/LED arrangement shown in "New circuit". When low, the blue LED is off and the red LED on. When high, the blue LED is on and the red LED off.I don't see anything in the datasheet of the inverter to suggest I am doing anything wrong with it? What happens is that the LED state transitions after a brief pause, when it transitions at all. It isn't reliable. Is it as simple as needing a 10k pullup to pin 1 of the inverter?

author: Benta
author_rank: Super Contributor
timestamp: August 01, 2024, 12:33:24 am
content: Remove R3 and add a pullup.

author: Terry Bites
author_rank: Super Contributor
timestamp: August 01, 2024, 08:15:26 am
content: The 650x has a Vdd of +5V. Add a pull up to +5V as shown. If the pull up is >>100 ohms then you can leave R3 where it is.An Rpu 1k to 10k will work fine. It is that simple.As shown in your schematic, the inverter input is charging up to an on state via a leakage current.Q1 etc can discharge it but provides no path to charge it again.For this particular converter you can drive it directly from a 5V CMOS logic output even if the inverter Vcc is less than 5V.The SN74LVC2GU04 data sheet says the inveter can be used as a "Down Translator". ie 5V down to the inveter's Vcc.Swap the LED colours. If Vcc is less than 5V, the blue LED might fail to light up. Blue LEDS need at least 3.3V.

author: brucehoult
author_rank: Super Contributor
timestamp: August 01, 2024, 09:13:46 am
content: Also can't both LEDs can be driven by one inverter? It can source and sink the same amount of current.
Strange PCB feature (PSU line filter) - Page 1
Forum section: electronics / beginners

author: Phaedrus
author_rank: Frequent Contributor
timestamp: September 05, 2013, 11:02:14 pm
content: So I was dissecting a 700W ATX PSU, a very high end one, and found an unusual design feature. As you can see in the attachment, there are these unusual needle shaped solder points. These are across the windings of a common mode choke in the line filter, right before the bridge rectifier. I cannot fathom the purpose of this feature. I asked our consulting engineer with 25 years experience, and he has no idea either.What's up with this?

author: AlfBaz
author_rank: Super Contributor
timestamp: September 05, 2013, 11:22:52 pm
content: Doesn't look like the picture uploaded properly

author: Fsck
author_rank: Super Contributor
timestamp: September 05, 2013, 11:31:17 pm
content: 0kB photo.

author: Phaedrus
author_rank: Frequent Contributor
timestamp: September 05, 2013, 11:34:20 pm
content: Crap. I'll reupload when I get home.

author: David_AVD
author_rank: Super Contributor
timestamp: September 06, 2013, 12:18:03 am
content: Spark gap?

author: free_electron
author_rank: Super Contributor
timestamp: September 06, 2013, 12:39:53 pm
content: Flashover structure. This is a trick used to be able to pass Hipot testing.During hipot testing they apply a few kilovolt and see if nothing explodes violently or sets on fire.This structure sparks over and protects the rest. One side of the structure should have a path to the chassis or neutral, possibly via a second of those spark gaps.This is common on off-line smps's.
Strange Power Supply Behavior - Page 1
Forum section: electronics / beginners

author: KingSolomon
author_rank: Contributor
timestamp: January 20, 2020, 10:31:21 pm
content: Hello-I recently got a new Siglent bench power supply. However, it has started to have a strange behavior of defaulting to constant current mode when I turn it on. I don't think that this is normal. Is this a common issue with an easy fix? I should also note that I have not put it under any stressful conditions since I bought it.Thank you!

author: Prehistoricman
author_rank: Regular Contributor
timestamp: January 20, 2020, 11:14:17 pm
content: What model is it?

author: KingSolomon
author_rank: Contributor
timestamp: January 21, 2020, 02:17:58 am
content: It's a Siglent SPD3303C.https://siglentna.com/power-supplies/spd3303c-series-programmable-dc-power-supply/

author: vu2nan
author_rank: Contributor
timestamp: January 21, 2020, 04:24:17 am
content: Could this be the problem/solution?https://siglentna.com/operating-tip/spd3303-c-stuck-in-constant-current/?pdf=7626Regards,Nandu.

author: Jwillis
author_rank: Super Contributor
timestamp: January 21, 2020, 04:51:14 am
content: Not sure what version you have but you could check if it has the latest firmware.https://siglentna.com/service-and-support/firmware-software/dc-power-supplies/#spd3303c-series

author: KingSolomon
author_rank: Contributor
timestamp: January 21, 2020, 05:06:40 am
content: I don't think that is the issue. I live in 120V North America, and have set the supply accordingly. Thank you
Strange resistor in HCPL3700 example schematic... - Page 1
Forum section: electronics / beginners

author: kirillandy
author_rank: Newbie
timestamp: February 22, 2020, 08:35:02 pm
content: Hi all!First time posting hereI've got a small question about a rogue resistor that appears on the example schematics of the HCPL3700 optocoupler, which I'd like to use as a switch.I've managed to surmise (I think...) that the output of the IC is a Darlington/Sziklai transistor whose main function is to amplify the input current using the small current at the base from the photodiode. There's also a bypass capacitor installed (as you do), but what is the Rl resisitor between Vcc and Vout?What's more, I've seen a version where it is connected to another capacitor (making it look like some low-pass filter, see Test circuits here:https://www.onsemi.com/pub/Collateral/HCPL3700-D.pdf) and a version where there is no additional capacitor which made me think it was some pull-up resistor (see attached schematics, I got them from some website)The datasheets never even mention the Rl resistor and it's making me wonder whether it's some obvious important component which any self-respecting EE will immediately recognize... making me rue the fact that I'm not a self-respecting EEWhat is it for? Is it necessary? And, more importantly, how will its resistance value affect the output of the circuit?

author: wraper
author_rank: Unknown
timestamp: February 22, 2020, 08:57:44 pm
content: Dunno why you find it strange. Optocouplers in general often are used with pull-up on the output. And for those with logic output like this one, it's given to be there. Optocoupler simply won't work without some sort of pull-up or some sort of small load from Vcc. Bypass capacitor is required too.

author: kirillandy
author_rank: Newbie
timestamp: February 22, 2020, 09:11:13 pm
content: Ah, OK, I was so distracted with figuring out how the transistors work that I forgot I was dealing with a simple logic circuit at the end of the day. So when the optocoupler is OFF (the led inside is OFF), the output is pulled up. And when the optocoupler is ON, the the transistor is open and current flows to ground? I always have trouble actually visualizing where current flows in different circuit states

author: wraper
author_rank: Unknown
timestamp: February 22, 2020, 09:16:45 pm
content: Quote from: kirillandy on February 22, 2020, 09:11:13 pmYes
Strange SOIC-8 package size? - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: November 26, 2020, 03:16:56 am
content: While placing components in KiCad am I stumbled upon a component that in the datasheet says it's a "SOIC-8(M)" package, it measures 5.99 mm while KiCad and the internet states it should be 4.9 mm, no matter type.Here are the link to the datasheet:https://www.mouser.dk/datasheet/2/268/micrf002_022-1891338.pdfBelow are two images from page 18 on the datasheet and kiCad.

author: wraper
author_rank: Unknown
timestamp: November 26, 2020, 03:28:57 am
content: Quote5.99mm or about is the standard dimension for SOIC. Dunno how you got that 4.9mm figure.

author: MarginallyStable
author_rank: Regular Contributor
timestamp: November 26, 2020, 03:29:57 am
content: Would trust a component datasheet over what "KiCad and the internet says" There are so many variations of package types.

author: wraper
author_rank: Unknown
timestamp: November 26, 2020, 03:35:17 am
content: 4.9mm is more like VSSOP/MSOP

author: Nerull
author_rank: Frequent Contributor
timestamp: November 26, 2020, 04:08:25 am
content: You're looking at the wrong dimension: width vs length. Both kicad and your datasheet agree that a SOIC-8 is 4.9mm long.KiCAD uses E x F, your datasheet lists H and F

author: FriedMule
author_rank: Frequent Contributor
timestamp: November 26, 2020, 04:15:08 am
content: I did get the measurement from both KiCad and several datasheets, but have now found thishttps://www.vishay.com/docs/83247/83247.pdfLOL okay, have I measured the wrong dimension?? :-)So the 3.9 mm is not the short dimension but the "innermost" size?

author: exmadscientist
author_rank: Frequent Contributor
timestamp: November 26, 2020, 04:29:29 am
content: Yes, 3.9mm is the body dimension rather than the leads dimension.I've attached JEDEC MS-012 Issue F, which is about as close to "official" as it gets for a definition of SOIC (Narrow) parts. It is unpleasant to read, but it is authoritative.

author: Nominal Animal
author_rank: Super Contributor
timestamp: November 26, 2020, 05:30:14 am
content: You can also useEasyEda(online free EDA, with a simple browser-based user interface) to explore a lot of "official" part footprints (those sold by LCSC.com).

author: FriedMule
author_rank: Frequent Contributor
timestamp: November 26, 2020, 12:59:16 pm
content: Thanks to you all am I a big step further:-)By the way, I have no idea if this circuit will work, should I ask my questions here or start a new thread with the right tittle?

author: jmelson
author_rank: Super Contributor
timestamp: November 26, 2020, 04:33:05 pm
content: Quote from: FriedMule on November 26, 2020, 03:16:56 amThere is body dimension, edge of lead dimension, center of pads to center of pads dimension, and outer edge to outer edge measure.All different, you have to be sure what the measurement refers to.Jon

author: FriedMule
author_rank: Frequent Contributor
timestamp: November 27, 2020, 04:31:04 am
content: Yes that's important to double and triple check! Thanks for your constructive comment! :-)
strange values when manual range selecting the Fluke 187 capacitance measurment - Page 1
Forum section: electronics / beginners

author: vinyl
author_rank: Newbie
timestamp: July 19, 2019, 11:29:30 pm
content: Hi.When my fluke 187 selects the capacitance measurment mode manual range(only on 100uF and 1000uF), it reads strange values with the lead open.lead openManual Range 100uF 2.0uF1000uF 16uFIs this normal?Lead open statusIt is normal to read very small values (0.067nF) at the manual range 1nF and 10nF, but it is difficult to understand that only the 100uF and 1000uF ranges are strange values.Five hyphens are displayed in other manual ranges (lead open 1uF, 10uF, 10mF, 50mF).

author: evava
author_rank: Regular Contributor
timestamp: July 20, 2019, 11:48:00 am
content: Hi,It is ok, same at me.It is sufficient to push leads into terminals.Try it!

author: vinyl
author_rank: Newbie
timestamp: July 22, 2019, 01:06:08 am
content: Thank you.Insert two leads into the input terminal and it is OK.
Strange VCA/OpAmp Audio Issue - Page 1
Forum section: electronics / beginners

author: gnif
author_rank: Unknown
timestamp: April 05, 2016, 07:40:42 am
content: Hi All,I have built a voltage controlled amplifier for a dual stereo volume control on my pre-amp. The circuit uses a SSM2164, which drives two NE5532 opamps to provide dual stereo outputs with independent volume levels, one to drive the rest of the pre-amp (active crossovers, etc), and the other to drive a pair of headphones.Works great and all, very happy with it but recently it has developed a very odd issue. On the headphone output, from time to time the audio gets messed up, it seems like all vocals are being removed from the audio. If I disconnect and reconnect the ne5532 opamp on the output it returns to normal, but every few days it reoccures. I have also noted that just switching off and on again fixes it also, so it is not a bad joint on the DIP socket.If anyone could provide some insight as to what could possibly be the cause here it would be greatly appreciated. Clearly the opamp is entering some mode where it is becoming a differential comparitor which removes the vocals, but I do not understand how this can just happen at random.

author: gnif
author_rank: Unknown
timestamp: April 05, 2016, 07:44:35 am
content: Typical, I just found the issue, its a bad connector on the headphone jack shorting the left and right channels.

author: Alex Trofimov
author_rank: Contributor
timestamp: April 05, 2016, 10:42:15 am
content: If shorting left and right channels together lead the vocal to disappear, it means that your left and right channels are opposite in phase. It shouldn't be so.
Strange voltage measurements on power supply - Page 1
Forum section: electronics / beginners

author: PeterV
author_rank: Newbie
timestamp: February 01, 2015, 09:01:42 am
content: Hi,I tested (measured) some older power supplies from different devices (3.7V, 4.5V, 12V-1A, etc)Half of them are giving much higher voltages... like: 19V instead of 12V, 20V instead of 16V, even 9V in stead of 3.7V...So I tried a working power supply for a NiMh battery of 9.6V / 600mA. The battery gave 10.3V and de power supply 25.6V...Settings on meter : DC, 200VAre these supplies or my meter broken?Has it something to do with the fact that there is no working circuit?It tried batteries:3V gave 3.14V9V gave 9.46Vnew 1.5V gave 1.61Vhome AC gave 224V (220V for Belgium)Someone an idea?

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 01, 2015, 09:09:09 am
content: When you say "power supplies" I assume you mean inexpensive "wall-warts".These are typically NOT regulated, and they very commonly have a higher output voltage when NOT loaded.I also assume that your meter is a typical modern DMM, etc.That means that it has a very high impedance to NOT load down what you are measuring.So what you are measuring is the "open circuit" (unloaded) voltage of low-end power supplies.This is completely ordinary and expected. The nominal voltage ratings are typically the LOADED design target.

author: Zero999
author_rank: Super Contributor
timestamp: February 01, 2015, 09:48:41 am
content: Yes unregulated wall warts always give a higher voltage when unloaded.It's also true that batteries give a higher voltage when fresh and unloaded.It's very important to take the above into account when selecting components, to avoid blowing things up.

author: PeterV
author_rank: Newbie
timestamp: February 01, 2015, 09:57:11 am
content: Yes, I didn't know.I have plans to work with micro-electronics...Did you hear about the "Ardumower project" yet?http://www.ardumower.de/index.php/en/I want to learn and to fix my broken mower...Big challenge...Maybe I'll need you more in the future...I added picture now.So suggestions on materials for my "lab"?Greetz

author: Rick Law
author_rank: Super Contributor
timestamp: February 01, 2015, 07:22:17 pm
content: Quote from: PeterV on February 01, 2015, 09:57:11 amYou should consider one of those step-down (buck) converters to control your actual output voltage. For the kind of app you are saying (under 1amp ish), The CV buck boards are well under $2-3, the CC/CV are well under $3-5.The boost+buck is also a good choice. It first boost the voltage to max (lm2577 max, 30volt-ish) then buck it back down to what you need. So it can supply 2v-27v with any of DC wall-wart with enough power (watts).These low cost boost/buck are not lab grade but they are more than adequate to power an arduino or something like that.For a digital controlled buck, see this thread:https://www.eevblog.com/forum/reviews/b3603-dcdc-buck-converter-mini-review-and-how-the-set-key-could-be-fatal/
Strange wiring question - Page 1
Forum section: electronics / beginners

author: digik
author_rank: Regular Contributor
timestamp: December 08, 2016, 07:58:09 pm
content: I've seen this so many times, but never figured out why on earth are wires in some big amplifier and other equipment wired like that:I don't know if it's clear from the picture, but those wires are non soldered directly on the pcb, but wrapped in those "pillars" instead (which are of course soldered on the PCB). So why are they not directly soldered on PCB?

author: Rerouter
author_rank: Super Contributor
timestamp: December 08, 2016, 08:12:09 pm
content: I believe it's 1 part simplified assembly, as the boards can just come with them preinstalled so the worker can solder to them with the board mounted in place /add additional connections to the same node if needed.And 2, to possibly reduce the strain in the connection point. In your image it looks like they used a wire wrapping tool, cannot tell if they soldered afterwards, but it tends to reduce the chance of snapping such as being pinned against the edge of a hole in fibreglass.

author: TheDane
author_rank: Regular Contributor
timestamp: December 08, 2016, 08:34:05 pm
content: The joints can be extremely durable, here's a part from wikipedia:"Wire wrap construction can produce assemblies which are more reliable than printed circuits: connections are less prone to fail due to vibration or physical stresses on the base board, and the lack of solder precludes soldering faults such as corrosion, cold joints and dry joints. The connections themselves are firmer and have lower electrical resistance due to cold welding of the wire to the terminal post at the corners."Rerouter is right - here's the link to the wiki article:https://en.wikipedia.org/wiki/Wire_wrapSoldering the joint can introduce noise due to the Seebeck effect (different metals - and a temperature difference = magnetic field, voltage across a wire) Besides, the wire is cold welded from the bending so there's no need.They're quite easy to make too - just get a wire wrap gun!

author: Brumby
author_rank: Unknown
timestamp: December 09, 2016, 07:05:39 am
content: Try soldering a multi-strand wire directly into a PCB hole - especially high strand count. A solid PCB pin is infinitely easier.Hand soldering to this will be much quicker.
Strategy for Car-Battery Voltage Regulation - Page 1
Forum section: electronics / beginners

author: little_engineer
author_rank: Newbie
timestamp: June 12, 2012, 11:48:18 am
content: Hello All,SUMMARY: Voltage range 0.1v - 10v - How do I regulate voltages greater than 0v, into 5v?I'm monitoring a circuit in a car that powers the interior lights. When the doors are open they are on, when they are closed they are off. I would like to regulate the voltage so that when the lights are on the breakout circuit = 5volts, when the lights are off it = 0v. I would like to use an arduino board to read these states.Here's the problem:I have measured the voltages produced in this circuit and off (all doors closed) = 0v, which is fine, but if one door is open, I have a reading of 0.1v, and if all the doors are open I have a reading of around 7v (+/- 3v it is very unstable). Is there away of regulating all values that are greater than 0v, into 5v?Any direction with this problem would be much appreciated.regards,Anthony.

author: Psi
author_rank: Super Contributor
timestamp: June 12, 2012, 01:53:15 pm
content: The 0.1v sounds like a mistake.It should be much higher when any door is open.I would have expected ~12V when any door is open and less than 0.5V when all doors are shut.You can use a voltage divider (two resistors) to scale the car voltage range of 0->13.8V to 0->5V.10k and 5.6K should work fine.

author: little_engineer
author_rank: Newbie
timestamp: June 12, 2012, 02:20:19 pm
content: @Psi: Thanks for the reply. I'll retake the measurements.Cheers.
Stray Commodore 64 graphics questions you might have. - Page 1
Forum section: electronics / beginners

author: RJSV
author_rank: Super Contributor
timestamp: April 07, 2023, 09:15:26 am
content: Hi, I've worked as a tutor before (calculus and basic physics questions).Anybody with stray question(s) on Commodore 64 (vintage) graphics 'Hires' modes can always ask.Either the formats or any simple coding questions, I can try, (although it's been 40 years, lol.)Did conversion rewrite, XEVIOUS circa 1986.
Streaming music through Bluetooth without microprocessor. - Page 1
Forum section: electronics / beginners

author: DanioIO
author_rank: Contributor
timestamp: September 06, 2014, 07:51:41 pm
content: Hi,i would like to make a simple wireless audio player to which i send data out off my smartphone using bluetooth. I had use a bluetooth adapter with RS-232 output but i would like something that will output i2s data, can i found any converter from UART to i2s?

author: janekm
author_rank: Unknown
timestamp: September 06, 2014, 08:56:23 pm
content: That wouldn't make any sense. You can get Bluetooth modules with I2S output. Google's your friend.
Stripline Stackup for EMI - Page 1
Forum section: electronics / beginners

author: Kasper
author_rank: Frequent Contributor
timestamp: May 06, 2020, 08:31:08 pm
content: Hi Everyone, thanks in advance for any help.I have heard that running clock traces internally reduces EMI since outer planes act as shields.Sounds simple but is it always true? What about a 4 layer PCB with relatively thick middle as shown in stackup 1:Stackup 1:1 - GNDd1/22 - SIGd2/3d2/3d2/3d2/3d2/33 - PWRd3/44 - GNDAssumptions:1 - Majority of return current (from signal on layer 2) travels through layer 1 since it is much closer to layer 2 than layer 3 is.2 - Current travelling through an external plane emits as much EMI as an equivalent amount of current travelling through an external trace would.Conclusion:Stackup 1 would radiate as much EMI as if layers 1 and 2 were swapped (signal on external layer).Questions:Are my assumptions correct and my conclusion valid?Is it fair to say a relatively thin middle as shown in stackup 2 would be best for EMI?Stackup 2:1 - GNDd1/2d1/2d1/22 - SIGd2/33 - PWRd3/4d3/4d3/44 - GNDIs it ok to use PWR as the return plane? Would stackup 3 be better?Stackup 3:1 - GND / PWRd1/2d1/2d1/22 - SIGd2/33 - GNDd3/4d3/4d3/44 - GND / PWRWould an even stackup (all dielectrics having same thickness) be sufficient?Looks like stackup 1 is more common than 2/3, is that right?Would stackup 2 or 3 cost more than stackup 1?Are there other things I should consider?
Stripping/Tinning/Soldering Litz wire and other small AWG wire? - Page 1
Forum section: electronics / beginners

author: MathWizard
author_rank: Super Contributor
timestamp: March 19, 2020, 09:45:55 pm
content: I have some Litz wire, the real fine, braided wire, with string/wool like insulation.I don't have experience with this stuff besides de-soldering AM/FM antenna coils in cheap radio's.Trying to cleanly strip fine gauge mag. wire, w/sandpaper is bad enough. How is litz wire meant to be cleanly stripped?On fine gauge mag. wire and litz wire, I'm just using the soldering iron, to cook off the insulation, and hoping a ball of solder will tin it.That's a pretty dirty way to do it, what's a better way ?

author: jmelson
author_rank: Super Contributor
timestamp: March 19, 2020, 09:48:26 pm
content: Quote from: MathWizard on March 19, 2020, 09:45:55 pmThat is basically the way it is done. You can't sand off the varnish as on solid magnet wire, you have to burn it off. It may be a bit easier with a solder pot, but an iron will do it, too.Jon

author: MathWizard
author_rank: Super Contributor
timestamp: March 19, 2020, 09:54:30 pm
content: Ok so I better just turn the temp down and try that next time. I'd hate to think how cooked/oxidized some of these little wire ends get.This is terrible, poor little wires, just want to do their job
stroboscope schematic - Page 1
Forum section: electronics / beginners

author: J4e8a16n
author_rank: Regular Contributor
timestamp: August 10, 2015, 01:12:35 pm
content: Hi,Can I create a stroboscopic lamp controlled by my signal generator and a battery with a 12 V bulb?The mosfet is a 2N7000Should I use a transistor?JP

author: Zero999
author_rank: Super Contributor
timestamp: August 10, 2015, 01:34:19 pm
content: The 2N7000 is a transistor. It would be better if it's connected in series with the LED, rather than in parallel with it.

author: J4e8a16n
author_rank: Regular Contributor
timestamp: August 10, 2015, 04:48:03 pm
content: Thanks for your answer,It works but the lamp is too slow. I replaced it with a led.But, is there another kind of bulb that would produce more light and be more reactive?JPD

author: mcinque
author_rank: Unknown
timestamp: August 10, 2015, 04:57:21 pm
content: Leds are very fast, and can be very bright, depending the wattage you use. What kind of led are you using now?If you want really a huge light, the fastest and brightest lamps are xenon bulbs, but of course that is a completely different schematics and you must be aware of potential issues (for example: very high voltages!)

author: alsetalokin4017
author_rank: Super Contributor
timestamp: August 10, 2015, 05:14:59 pm
content: A high-efficiency LED is probably your best bet in such a simple circuit.But you should drive your mini-mosfet with a square pulse instead of a sine wave. Vary the duty cycle too, for best results. For a good strobe effect (freezing motion, etc) the "on" duty cycle should be very short.I've made effective LED strobes using a 555 (either one-shot and externally triggered to synch to rotating machinery, or as built-in oscillator that can be set to arbitrary frequency). A 555 can be made to produce nice short pulses so that the strobe is effective in freezing motion.For example see the circuit below. The basic timing signal (from signal generator, oscillator, or optical trigger, etc.) comes in to Pin 2, and the circuit drives an ordinary high-efficiency 5mm LED with enough brightness and short pulse width to work as a small stroboscope.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: August 10, 2015, 05:21:23 pm
content: Quote from: Hero999 on August 10, 2015, 01:34:19 pmYes, all mosfets are transistors, but not all transistors are mosfets!The 2n7000 is an n-channel mosfet. A Metal-Oxide Semiconductor Field-Effect Transistor.Many people just say "transistor" when they really mean "bipolar transistor" and just say "mosfet" when they really mean ... "mosfet".

author: mcinque
author_rank: Unknown
timestamp: August 10, 2015, 05:35:04 pm
content: Quote from: alsetalokin4017 on August 10, 2015, 05:14:59 pmexcellent advice!

author: J4e8a16n
author_rank: Regular Contributor
timestamp: August 10, 2015, 06:43:32 pm
content: Very good,I will do that!JPD
Struggling to identify AC solenoid suppressors - Page 1
Forum section: electronics / beginners

author: mc
author_rank: Regular Contributor
timestamp: August 16, 2015, 10:49:15 pm
content: I'm currently working on retrofitting an old CNC milling machine, and am currently working on the tool changer.All the pneumatic valves on the changer are 230V, and have a suppressor fitted into the DIN connectors. Are these still available, if so what are their proper name, or is newer practice (this mill dates from the late 80s/early 90s) to mount suppressors elsewhere?I've tried searching for new DIN connectors with built in suppressors, but my searches have drawn a blank, and I suspect I'm searching for the wrong thing.

author: IconicPCB
author_rank: Super Contributor
timestamp: August 16, 2015, 11:07:53 pm
content: look for MOVs.

author: mc
author_rank: Regular Contributor
timestamp: August 18, 2015, 12:04:06 am
content: Thanks for that.After searching for that, the penny dropped and I searched for "solenoid DIN plug surge", which found a couple suitable sources.Seems to be the more common term is Protected/Protective circuit connectors, which turned up far more suitable sources.As usual, it's all about knowing the correct term to search for!

author: Paul Moir
author_rank: Frequent Contributor
timestamp: August 18, 2015, 12:12:08 am
content: They're often built into pneumatic valves, so if you're replacing the valves check to see if the replacements have one already.I often use a TVS rather than a MOV because they're smaller and easier to cram into a DIN connector.

author: rvalente
author_rank: Frequent Contributor
timestamp: August 21, 2015, 10:51:41 pm
content: These?Wago, Phoenix contact and weidmuller offers similar stuffhttp://shop.murrelektronik.com/en/Connection-Technology/Valve-Connectors/
Struggling to repair a Tek TDS5052B - Page 1
Forum section: electronics / beginners

author: magnetchief
author_rank: Contributor
timestamp: February 22, 2022, 06:45:41 pm
content: Hi, I have an old Tek TDS scope.The HDD had previously crashed, I had none of the original software for reinstallation of the drive.I followed the excellent rebuild blog from Ilya @ xDevshttps://xdevs.com/fix/tds5000b/#resultI replace the HDD and cloned the image as per his blog.Added more Ram and replaced the processor cooling fan.After booting up, the scope seemed to work as expected.I installed the various windows and Tek drivers again as per his blog.I ran the various diagnostic testes and all passed.But, I have no waveform displayed on the scope from either channel.I tried to set a couple of measuring options using a PTS input into channel #1. You can see the measurements of the input signal on the attached photos, but no waveforms are visible.Am I missing something here? Please forgive my lack of experience, but would really like to get this old scope working again.Many thanks for any advice offered.

author: Johnny10
author_rank: Frequent Contributor
timestamp: February 22, 2022, 08:43:05 pm
content: Someone had this problem a while back on another thread.https://www.eevblog.com/forum/repair/tektronix-tds7104-no-waveform-on-screen/msg1984160/#msg1984160

author: magnetchief
author_rank: Contributor
timestamp: February 22, 2022, 10:06:42 pm
content: Many thanks.I think you are onto something.I will check it out tomorrow and update.Thanks again.

author: magnetchief
author_rank: Contributor
timestamp: February 23, 2022, 02:56:52 pm
content: Well that took all of two minutes to correct.You were spot on, thanks for the lead.
STS8C5H30L suitable for arduino control? dual n/p channel for isolation? - Page 1
Forum section: electronics / beginners

author: telarc
author_rank: Newbie
timestamp: February 22, 2016, 12:35:27 am
content: Hi, I need to route a 5V 1A supply to various parts of a circuit, but only one part at a time (isolated the rest of the time). The only way I've discovered how that might be possible is using isolated DC-DC converters or maybe a dual chan n/p mosfet for each route. I'm wondering ifa) a STS8C5H30L Dual N/P-channel MOSFET (http://docs-asia.electrocomponents.com/webdocs/097a/0900766b8097ae0d.pdf) can be driven from 5v logic and handle 1A, Ive sorted through a number of part sheets and believe I've narrowed it down to this with it's vgs rating and low on draw, but I cant be certain I've understood it all correctly.b) Can I use the n and p channel mosfet to isolate the + and gnd of that 5v 1A output? I would like to use a number of these with a paralleled input voltage and then direct which part of the circuit that voltage goes to by turning them on/off.EDIT: Attached a picture as a rough example, apologies for basic errors in it, I'm not very skilled with mosfets. In this example I would like to switch the charger between batteries (works manually).EDIT: Maybe I can isolate the mcu from the mosfet control with opto isolators so I can avoid some of the problems in those images.EDIT: Relays would work, but I need to activate 200+ times a day
Stub Style vs Feed Through Terminator - Page 1
Forum section: electronics / beginners

author: EE_newbie
author_rank: Newbie
timestamp: July 16, 2021, 03:13:26 pm
content: Hello,EE newbie here. Can someone please explain the difference between Stub Style vs Feed Through Terminators? I need a 150 Ohm Stub Style terminator that I cannot find anywhere. I was only able to find a 150 Ohm Feed Through terminator. Can I use the Feed Through terminator instead of the Stub Style terminator? If the answer is yes, then we are all good. If the answer is no, then read below.It looks like the most common impedance of terminators available in the market are 50 Ohm and 75 Ohm terminators? Can I put two 75 Ohm terminators or three 50 Ohms terminators in series to yield the 150 Ohms impedance that I need? If putting them in series is a possibility, how would I connect the 2 or 3 terminators in series? Any help is much appreciated. Thanks.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 16, 2021, 03:21:28 pm
content: For what cable/connector/system? Traditional BNC at least isn't 150 ohms by a long shot...Most differential pairs aren't, either, though I see a fair number of hits for Modbus and DMX. If that's what you have, neither is anywhere near fast enough to have a problem, with either type of terminator, at least electrically speaking and assuming the connectors mate properly and everything.Tim

author: EE_newbie
author_rank: Newbie
timestamp: July 19, 2021, 05:35:18 pm
content: Thank you for your response. I guess I should have provided more information in my initial post. What I am looking for is a 150 Ohm external load to provide to the Audio Input 1 of the Aeroflex 3920B Tester. Below is a video of the tester.. Watch between 4:56 and 6:28. The 3920B has an internal load of 600 Ohm only, but I need to use 150 Ohm, so thought about using an external load in Audio Input 1 for the required 150 Ohm. The problem is there are no Stub Style BNC terminator available in 150 Ohm. Only found a Feed through BNC terminator in 150 Ohm. So was wondering whats the difference between the stub style and feed through terminator. Also wondering what is the internal circuitry of a terminator looks like. As I asked in my initial post, can 2 or 3 terminators be put in series to yield the 150 Ohm load that I need?
Stubby fingers vs Ben - Page 1
Forum section: electronics / beginners

author: PerranOak
author_rank: Frequent Contributor
timestamp: February 23, 2022, 07:54:56 pm
content: So, I am building the Ben Eater 6502 breadboard machine for fun.The problem I have is with my stubby fingers: I simply cannot get all the leads into the breadboard without squashing it all.What it need is something I can put the cpu into and then feed wires out to the breadboards to give more room.Every time I Google “break out board”, etc. I can ads for bl00dy rpi and so on.Is there any genericthingI can get (40 pin) that will do the job?Cheers.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 23, 2022, 07:59:11 pm
content: Serrated tooth tweezers about 6" long. Some people call them "pick-ups." That's what I use. My fingers aren't particularly stubby, but in the Winter, they are cracked, bleeding, and painful. If you can get non-magnetic ones, you will be happy, but regular also work.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: February 24, 2022, 02:47:02 pm
content: Quote from: PerranOak on February 23, 2022, 07:54:56 pmIs this any use to you?https://www.ebay.com/itm/40-Pins-ZIF-Socket-to-DIP-Screw-terminals-Breakout-Board-Module-/302297245415

author: PerranOak
author_rank: Frequent Contributor
timestamp: February 24, 2022, 05:02:04 pm
content: That is perfect mate, cheers!
AoE question 2.9 - Page 1
Forum section: electronics / beginners

author: bd139
author_rank: Super Contributor
timestamp: December 27, 2017, 10:20:33 pm
content: Edit - I was helping a friend with something and I can't answer it as I am a royal dumbass when it comes to theory, so I got him to post from my PC and it came out as my account rather than hisFail.---Here's the question:I can derive this via trial and error but I we can't work out how to derive it mathematically:If you want a current source constant to 1% over a load voltage range or 0 to +10 volts, how large a voltage source must you use in series with a single resistor?Any takers - I can simulate it in LTspice but can't derive it...

author: rfun
author_rank: Newbie
timestamp: December 27, 2017, 10:26:55 pm
content: Yes he's a dumbass

author: Audioguru
author_rank: Super Contributor
timestamp: December 27, 2017, 10:40:49 pm
content: You need a magician to get current from a resistor that has 0V.

author: bd139
author_rank: Super Contributor
timestamp: December 27, 2017, 10:43:43 pm
content: A resistor of 0.000001 volt across it still gets the same current. I think it's a ratio of voltages. I can't work it out.For example delta-I is 0.01 and delta-V is 10 so what is Vsource? R cancels out I am sure. Just can't work it out. It's late and I'm brain damaged from all the alcohol at ChristmasBest guess is around 1KV

author: Rerouter
author_rank: Super Contributor
timestamp: December 27, 2017, 11:08:24 pm
content: I am likely not fully grasping the question, but...if you need less than a 1% variation in current while changing the contribution of the load between 0-10V, then that is easy, 10V needs to be less than 1% of the total voltage drop, so you need a voltage source of atleast 1000V to have less than 1% deviation

author: 2N3055
author_rank: Super Contributor
timestamp: December 27, 2017, 11:29:29 pm
content: 1010V1000 Rx For top resistor, 10 Rx for bottom for I= 1 Ix1000V on top one , 10V on bottom one.1000 Rx for top resistor, 0 Rx for bottom one, 1010V/1000 Rx = 1,01 IxDifference 1%+

author: bd139
author_rank: Super Contributor
timestamp: December 28, 2017, 12:11:13 am
content: Perfect. That makes sense now. Thank you.

author: rfun
author_rank: Newbie
timestamp: December 28, 2017, 12:35:14 pm
content: Thank you 2n3055!
Study Material - Page 1
Forum section: electronics / beginners

author: ahnuts72
author_rank: Regular Contributor
timestamp: February 20, 2013, 07:25:08 am
content: OK didn't know of this should go in the sticky or if I should start a new topic.I'm wondering if anyone could recommend a book to read that showswhy a component is in a circuit. All of the ones I've purchased or found explain how a component works but get a little fuzzy as to why it was selected and used in a circuit.Maybe someone would be kind enough to pick a small analog circuit and kinda explains why a few of the components are in the circuit.Like a board layout I asked about it has an output pin on the ic but it also has a voltage being applied to the same pin through a resistor.Sent from my NookColor using Tapatalk 2

author: Kremmen
author_rank: Super Contributor
timestamp: February 20, 2013, 07:37:25 am
content: I am afraid that could be a long and rather fruitless road. In my view it would be explaining a concept by decoding individual instances. Far better to first learn the concepts, after which applying them will be application of general principles to individual cases rather than the other way around.Having said that, there are "advanced" cases where the reason for existence of a component in a circuit is not obvious. The problem is that these cases are too numerous to list exhaustively. Again, focusing on a certain topical area + experience will bring such cases to the front and reveal the reason why. It would be pointless to just list all of such cases, not to mention practically undoable.As to a book, one like you ask for does not exist AFAIK, and for a reason (the above). "The Art of Electronics" has been mentioned in this forum lately. While not that book, it is well worth studying. Once you master that, the circuits will have significantly fewer mystery components.
study of CSI1802X schematic, 12V rail question - Page 1
Forum section: electronics / beginners

author: cellularmitosis
author_rank: Unknown
timestamp: April 02, 2014, 01:08:57 am
content: Hey all,I've been studying the CSI1802X schematic, and I decided to sketch it up in KiCAD so I could rearrange it to try to understand it.One part which I don't understand yet is the way they float the 12V supply section. The entire 12V section is floating via a transformer, and the only point which ties it to the rest of the circuit is where the relay transistor base pin connects to the main negative output pin.With the way I have it sketched up, I don't see how that base pin will ever move anywhere (i.e. I don't see how the relay will ever switch).Did I make a mistake in transliterating this schematic?Here's the github page:https://github.com/pepaslabs/CSI1802XThe CSI1802X:http://www.circuitspecialists.com/bench-power-supply-csi1802x.htmlThe manufacturer's schematic:http://www.circuitspecialists.com/pdf/1802X_schematic.pdf

author: pa2ees
author_rank: Contributor
timestamp: April 02, 2014, 03:31:56 am
content: Quote from: cellularmitosis on April 02, 2014, 01:08:57 amI think your schematic is correct as far as the relay goes (I have not looked too much into the rest of the circuit).I agree that the base will not move anywhere *with respect to the negative output pin*.However, because the negative output pin is not shorted to the 12V circuit section's ground rail, the base of the transistor and the 12V circuit section GND rail are not necessarily the same voltage. In fact, if there is indeed +12V from IC5 Vout to IC5 GND, that means that there should be current flowing through R6, and into the base of the transistor Q3. This should turn on the transistor and subsequently turn on the relay.An interesting point to note is that the GND rail of the 12V circuit section will probably be lower potential than the negative output pin.In summary, the voltage of the base of the transistor with respect to the emitter is the important bit, as it will determine whether there will be Base-Emitter current, or not. The voltage of the base of the transistor with respect to the negative output pin is not important.I hope that explains it clearly enough.- Erik

author: cellularmitosis
author_rank: Unknown
timestamp: April 03, 2014, 03:17:01 am
content: Thanks! I'll put on my thinking cap and think about that for a while.
Stuff used to "gunk" capacitors and other components - Page 1
Forum section: electronics / beginners

author: electronics man
author_rank: Frequent Contributor
timestamp: May 05, 2014, 05:48:38 pm
content: I'm looking for that gunk used to keep capacitors and other things from vibrating loose. I don't know what it's called and where to search for it, Anyone know?

author: rdl
author_rank: Super Contributor
timestamp: May 05, 2014, 07:09:30 pm
content: I think it's usually just hot glue. Sometimes people call it silicone, and maybe it is sometimes, but silicone is a lot more expensive so I doubt it's used on the cheaper stuff. Also, when/if silicone is used it needs to be a special acid free type so that nothing corrodes.

author: SeanB
author_rank: Super Contributor
timestamp: May 05, 2014, 07:32:04 pm
content: Any acetoxy free silicone ( does not smell of vinegar) will work, along with some hot melt adhesives. What works well is a flexible polyurethane, either a single component one like Sika, or a 2 part one. You can also use a gel based superglue, though you will have bloom from it. Even an epoxy will do depending on the environment.

author: electronics man
author_rank: Frequent Contributor
timestamp: May 05, 2014, 09:11:14 pm
content: ok thank you very much for the help
Stupid Question about FET's - Page 1
Forum section: electronics / beginners

author: Monomo
author_rank: Newbie
timestamp: October 28, 2013, 10:56:09 pm
content: HiI may have better listened in class, but I was young and dump, so:Is there an Voltage-Drop over the Drain-Source on an FET?I know the other way around, Source-Drain, there is an Voltage-Drop, because of the diode.Maybe I think to match of a FET as a Transistor.Monomo

author: c4757p
author_rank: Super Contributor
timestamp: October 28, 2013, 11:01:51 pm
content: There is no logarithmic/"fixed", diode-like drop, but there is a resistive drop, typically from 10 to 500 milliohms depending on the FET.

author: M. András
author_rank: Super Contributor
timestamp: October 28, 2013, 11:04:24 pm
content: the lowest i found was below 1miliohm

author: NickS
author_rank: Unknown
timestamp: October 28, 2013, 11:38:06 pm
content: The diode is just there to protect the FET.In day to day use it isn't used at all and has no impact on the circuit.

author: walshms
author_rank: Regular Contributor
timestamp: October 28, 2013, 11:43:29 pm
content: Quote from: NickS on October 28, 2013, 11:38:06 pmAPS uses those body diodes in their UPS products for charging the battery. Dave did a video on it.

author: c4757p
author_rank: Super Contributor
timestamp: October 28, 2013, 11:55:46 pm
content: Quote from: NickS on October 28, 2013, 11:38:06 pmNope, it's not there to protect the FET. A MOSFET is inherently a four-terminal device, with the fourth terminal (bulk) forming "parasitic" diodes to both ends of the channel. This ends up connected to one end, defining that end as the source. It's not built there intentionally for protection at all. There is at least one MOSFET in current production (theBSS83) which exposes all four pins instead of tying two together.

author: Monomo
author_rank: Newbie
timestamp: October 29, 2013, 06:25:42 pm
content: Quote from: c4757p on October 28, 2013, 11:01:51 pmThanks for the clarification.