hybridfree/eevblog-posts huggingface dataset:
What H bridge should I use? - Page 1
Forum section: electronics / beginners

author: little_carlos
author_rank: Regular Contributor
timestamp: August 04, 2014, 01:37:56 pm
content: Hi, im going to make a scale crane, not a strong one, im going to use 2 motors, one for x axis, and one for y axis, each of them draws at maximum 1 amp, at 15 volts, wich h bridge should i use? or its better to build one by myself?

author: Kremmen
author_rank: Super Contributor
timestamp: August 04, 2014, 04:06:45 pm
content: While there is a huge variety of components that will do the trick, allow me to be somewhat lacking in imagination and mention the trusty old workhorse L298. There is nothing fancy about it and it definitely is not cutting edge technology. But on the plus side it will work and it is trivially easy to apply. Datasheet here:http://www.st.com/web/en/resource/technical/document/datasheet/CD00000240.pdf

author: rob77
author_rank: Super Contributor
timestamp: August 04, 2014, 05:02:27 pm
content: +1and probably you could even buy a ready-to-go module. ebay is full of those modules - it's quite popular in the arduino community.
What happened to the 2N7000 model in ltspice? - Page 1
Forum section: electronics / beginners

author: ledtester
author_rank: Super Contributor
timestamp: December 18, 2022, 06:31:27 pm
content: Does the standard.mos file in your ltspice installation contain the 2n7000?This online version of standard.mos does:https://ltwiki.org/index.php?title=Standard.mosbut it doesn't appear in my standard.mos file (last updated in September).

author: mikerj
author_rank: Super Contributor
timestamp: December 18, 2022, 11:18:15 pm
content: Updated mine today and it has the 2N7002 but no 2N7000.

author: coppercone2
author_rank: Super Contributor
timestamp: December 18, 2022, 11:22:50 pm
content: its too powerful, they don't want it in the open like that

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: December 18, 2022, 11:51:04 pm
content: Quote from: ledtester on December 18, 2022, 06:31:27 pmI don't think anything happened to the 2N7000 model. It is not in the library on my installation.If you look at the parameters standard.mos file you will find that the 2n7000 and 2n7002 are identical.Ifyouhave added a part to the LTspice library it willnotbe removed by any updates.Jay_Diddy_B

author: Terry Bites
author_rank: Super Contributor
timestamp: December 19, 2022, 06:13:31 pm
content: there's nothing to stop you importing a spice model.www.analog.com/en/technical-articles/ltspice-simple-steps-to-import-third-party-models.html
What happens capacitor connected to '331 inv input, and supply voltage drops? - Page 1
Forum section: electronics / beginners

author: incf
author_rank: Frequent Contributor
timestamp: April 22, 2025, 05:10:28 pm
content: Suppose I have a '331 (TL331) comparator. And connected to its inverting (-) input is a 1uF capacitor charged to 30V.Then suppose that the supply voltage quickly drops to 15V.Will an internal structure in the '331 (TL331) cause the capacitor to discharge through the input pin?I'm familiar with the truth table for what the output will do outside of the common mode range. Mostly interested in what the inputs will do?Edit: https://www.onsemi.com/download/data-sheet/pdf/tl331-d.pdf

author: TimFox
author_rank: Super Contributor
timestamp: April 22, 2025, 07:21:45 pm
content: The LM331 is a voltage-to-frequency converter.Did you mean another device, maybe LM311?

author: incf
author_rank: Frequent Contributor
timestamp: April 22, 2025, 07:30:42 pm
content: Quote from: TimFox on April 22, 2025, 07:21:45 pmTL331 (https://www.onsemi.com/download/data-sheet/pdf/tl331-d.pdf)I've edited the original post to link to the datasheet
What happens if the output of an op-amp is pulled to VCC? - Page 1
Forum section: electronics / beginners

author: aiq25
author_rank: Regular Contributor
timestamp: August 29, 2017, 08:38:30 pm
content: I'm not too familiar with analog circuits so I have a question. What happens if the output of an op-amp is pulled to VCC while there is no power on VCC pin?My guess is there should not be any damage to the op-amp but I'm not sure.Reason I'm asking is because I have a case where the power to my circuit will be cut off but the output is pulled high via a resistor (1k Ohm). I don't want the op-amp to be damaged. Maybe adding a to the output diode will help.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: August 29, 2017, 09:14:26 pm
content: "Pulled" how? And to which Vcc? Its own Vcc or some other power rail in the system? I think we need a schematic.

author: danadak
author_rank: Super Contributor
timestamp: August 29, 2017, 09:19:28 pm
content: If OpAmp powered off Vcc, and Vcc is opened, no damage.If OpAmp powered off Vcc, and Vcc is shorted to ground, possible damage from inputs being drivenfrom a voltage source.If OpAmp powered off separate supply, and Vcc is opened, no damage.If OpAmp powered off separate supply, and Vcc is shorted to ground, possible damage. Could be thermal,or over current. Depends on protection designed into OpAmp.You could supply a schematic to vendor FAE for analysis. You would have to include power sequencingin the description.Regards, Dana.

author: Zero999
author_rank: Super Contributor
timestamp: August 29, 2017, 10:12:44 pm
content: Quote from: aiq25 on August 29, 2017, 08:38:30 pmYes, there's a possibility of damage, due to the upper output transistor being subjected to reverse bias, but it depends on the op-amp topology and the power supply voltage. If in doubt, connect the output pin to the Vcc pin via a diode: cathode to Vcc & anode to output. This will bypass the output transistor, if the output is dragged above Vcc.

author: aiq25
author_rank: Regular Contributor
timestamp: August 30, 2017, 03:10:26 pm
content: Attached is a block diagram. Sorry about it not being a proper schematic, this is something I was able to draw very quickly.The VCC of the op-amp is NOT the same as the VIN of the system. The VCC of the op-amp is reverse voltage protected by a diode, so VCC of the op-amp has about a 0.2-0.3 volt drop.The amplifier is just being used as a buffer. Perhaps it would be easier to replace this with a transistor based design so I don't have to worry about damaging the IC? I listed the 3 test cases in the block diagram.

author: Zero999
author_rank: Super Contributor
timestamp: August 30, 2017, 05:31:32 pm
content: As I said above, a diode between the output and the positive power terminal will protect against this.

author: aiq25
author_rank: Regular Contributor
timestamp: August 30, 2017, 05:39:06 pm
content: Quote from: Hero999 on August 30, 2017, 05:31:32 pmThanks!
What happens or can happen when you reverse polarity of 12V LED strip lights? - Page 1
Forum section: electronics / beginners

author: DW1961
author_rank: Frequent Contributor
timestamp: July 12, 2020, 09:20:04 pm
content: What happens or can happen when you reverse polarity of 12V LED strip lights?I've read where some are not protected from RP, but tehn read that diodes don't flow backwards, acting as a sort of resistor. Then I read some diodes can be damaged by reverse polarity becasue their resistance isn't strong enough.

author: Ian.M
author_rank: Super Contributor
timestamp: July 12, 2020, 09:32:06 pm
content: The strip itself for 'Dumb' single colour or RGB ones should be reverse polarity resistant. To run from 12V efficiently the LEDs will be arranged in series strings of three (or more if the individual Vf is under 3V) + a dropper resistor so no LED will see a reverse voltage over the 5V limit permissible for most types of LED.However if its made of smart individually digitally controllable LEDs, reverse polarity will instantly destroy them, and reverse polarity will destroy unprotected controller boards for 'dumb'LED strips.

author: DW1961
author_rank: Frequent Contributor
timestamp: July 14, 2020, 04:48:40 am
content: That's probably why the standard DLED plugs in a computer are plugged out for one of the pins? (No way to reverse them?)Thanks for the reply. I have read that if you reverse the polarity on the dumb 12V LED strips, they just don't work. No damage.But, are you saying if you plug an RGB strip into a controller, like the cheap ones you get from Amazon, it will instantly destroy the controller--what boards are unprotected these days?

author: Ian.M
author_rank: Super Contributor
timestamp: July 14, 2020, 04:58:44 am
content: No, reversing a dumb RGB LED strip shouldn't damage the controller, but reversing the supply to the controller will kill it unless its got extra cost parts to provide reverse polarity protection.

author: DW1961
author_rank: Frequent Contributor
timestamp: July 15, 2020, 05:29:17 am
content: Quote from: Ian.M on July 14, 2020, 04:58:44 amInteresting. I'll definitely remember that if I am working with bare wire supply to controllers. Thanks.
Delete Delete Delete - Page 1
Forum section: electronics / beginners

author: The_Almighty_Bacon_Lord
author_rank: Contributor
timestamp: March 09, 2016, 01:46:30 am
content: Delete Delete Delete

author: Ian.M
author_rank: Super Contributor
timestamp: March 09, 2016, 02:17:09 am
content: It depends. If you short a DC output power adapter through an ammeter, the odds of not damaging the adapter and not blowing the meter fuse aren't in your favour. If its cheap chinese sh-t it mighe even catch fire. If its high quality amd well designed, it may have foldback current limiting that makes it short-circuit proof but the initial current pulse may still be large enough to blow your meter fuse. Constant current limited adapters not specifically intended for Lead acid or LiPO battery charging are *RARE*.OTOH if you connect it to a voltmeter with a FSD greater than the output voltage it will do sweet F.A apart from reading the output voltageIf you want to check the adapter non-destructively, calculate an appropriate load resistor to draw the rated current (or just under) at the nominal output voltage, and put one with a high enough wattage rating in series with the ammeter.
What happens when MCU power up - cortex M4 - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: December 25, 2014, 07:39:53 am
content: 1. I want to know what happens when MCU powered up specific to cortex M4.2. I have attached one keil program using TM4C123GH6PM. Its basic program to start working.3. TM4C123GH6PM has 16Mhz internal OSC4. I had read that flash/ram in M4 are arranged in below sequence:Flash-> test+lireal , read only data , copy of ram data sectionRam -> Data section , bss section , heap , stack5. According to me the exact sequence is:Power up or any reset -> Internal clock 16Mhz init -> All peripheral/system register assigned default values -> bss section assign zero value -> ram data section assigned values from flash -> PC goes to reset handler
What happens when there is an I2C address conflict between GPIO expanders - Page 1
Forum section: electronics / beginners

author: SlowBro
author_rank: Regular Contributor
timestamp: November 07, 2017, 11:49:11 am
content: What happens when there is an I2C conflict between GPIO expanders such as theMCP23017where both chips are set to the same address, and their pins are set to output? Do they not work at all, do you get magic smoke, or do identical pins on both work identically, or is it device-specific e.g. this model might work identically but another might cause magic smoke...

author: rt
author_rank: Regular Contributor
timestamp: November 07, 2017, 01:28:20 pm
content: Your question is a bit unclear.1) Do you mean an I2C address conflict where for example two MCP23017 expanders are set up with the same I2C address?Solution: change the pull-up/down resistors on the address pins (A0-2) to change the address of one of the chips.2) Or that the output pins of two MCP23017 are connected to each other with both in output mode?The key here is that on the MCP23017 any output pin can only source or sink 25mA (see data sheet). Driving one pin high and the other low may well drive more current than that and blow one/both pins.Without a circuit diagram or a clearer application it's hard to say more.rt

author: SlowBro
author_rank: Regular Contributor
timestamp: November 07, 2017, 08:22:14 pm
content: Quote from: rt on November 07, 2017, 01:28:20 pmYes, an address conflict. If both are set to use the same address what would happen?(Edited the OP to clarify.)

author: rt
author_rank: Regular Contributor
timestamp: November 07, 2017, 09:05:04 pm
content: Quote from: SlowBro on November 07, 2017, 08:22:14 pmYou'll probably get garbage on the I2C bus because both MCP23017 chips will reply slightly out of sync (even if data is identical) and definitely out of sync if there is different data coming back to the microcontroller.I don't believe that I2C function is ever guaranteed for two devices with the same I2C address on the same bus.Can you outline why you are considering this approach? Extra current supply to a load? Surely just use a line driver as a high current buffer?rt

author: SlowBro
author_rank: Regular Contributor
timestamp: November 08, 2017, 06:27:16 pm
content: It's for the accidental situation where a user wouldn't pre-set the address jumpers differently than their existing GPIO expanders.What data would be coming back from a GPIO expander if it's output-only?
What IC/circuit am I looking for to switch power? - Page 1
Forum section: electronics / beginners

author: agehall
author_rank: Frequent Contributor
timestamp: April 07, 2023, 01:51:13 pm
content: I want to construct a small board that allows me to pass 12V at 15A to any of 24 pins, one by one all controlled by an MCU. The idea is to stress test custom built ATX PSU cables before I put them into an actual computer and verify they are making good connection using a thermal camera.This presented an interesting issue that I realized I don’t know how to solve. I want a single connection to my bench PSU that I can then direct to any of the pins in the test connector. At first I was thinking a simple MOSFET on each pin would do it, but when thinking more about it, I don’t see how this would work.What else, short of relays, can I use to enable the output on just one pin at the time?

author: BillyO
author_rank: Super Contributor
timestamp: April 07, 2023, 02:36:57 pm
content: MOSFETs.Does your MCU have 24 pins available?If not you can use three 74LS595. That way you can use 1 pin on the MCU to dive all 24 MOSFETs.

author: Ian.M
author_rank: Super Contributor
timestamp: April 07, 2023, 02:54:43 pm
content: Why would you even want to do that? Build a jig to zig-zag the circuit through the cable under test so you can apply your high test current to all the wires and contacts simultaneously in series. Include test points at each end of each wire so you can check the voltage drop, moving the red and black probes on to the next one alternately to match the zig-zag connections. *IF* you want to include a MCU and automate the test, you could use analog switches to connect the test points to a differential OPAMP buffer feeding the MCU's ADC, to automate the voltage drop testing without a DMM. You'll probably also want some means of controlling the current through the test jig, and the best option here would be to feed it from a synchronous buck regulator controller with enable pin (so you can shut it off) driving >30A MOSFETs, with its feedback biassed with filtered PWM from the MCU to control its output voltage. Include a heatsinked low ohm power resistor in the series circuit both as a load for stability and to develop a voltage across it for the ADC to read the current.
What if you did this with a SMPS ? - Page 1
Forum section: electronics / beginners

author: MathWizard
author_rank: Super Contributor
timestamp: February 04, 2023, 03:28:55 am
content: I was checking the allowable mini-TX power levels, and I read this.QuoteIs that so you don't interfere with industrial sites or hospitals ? Or more like the power grid, with such low frequencies, and large lengths ?So that's maybe 2-3x the frequency of a common computer SMPS. But so what if you instead of driving dozens of amps into a computer, you just put some load/big antenna on it. Would it do anything cool, or just make a pile of noise ? I'm just curious since they have such high power ratings, what would happen, to themselves.

author: Kim Christensen
author_rank: Super Contributor
timestamp: February 04, 2023, 04:52:38 am
content: The relatively short antenna length is just to reduce the range. The shorter the range, the more people in a given area can use the same frequency and not bother each other. (Wave length at 160Khz is 1.8 Km so a 30m antenna is not optimal)A computer SMPS produces a PWM squarewave, so yea, connecting an antenna to one of the transformer windings inside would spew a bunch of noise. That's why those power supplies have filters on the power connections: To prevent unintended RFI.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 04, 2023, 06:01:01 am
content: Wiring to an SMPS secondary (before the rectification and filtering) would be only slightly better than a spark gap transmitter...Depends on type. All of them will have sharp waveforms (read: tons of harmonics). Your antenna coupling network will require a strong lowpass or bandpass filter to deal with these. None of them are crystal controlled, so you won't be able to keep a, say, 500Hz CW channel (or whatever they're allocated as, at frequencies down there) tuned in. And many of them aren't fixed at all, where the switching frequency depends on load and component values rather than a fixed (e.g. RC timer) reference -- and wildly so, far more than you'll be able to hold a, say, NBFM (couple kHz) channel (if such are permitted in the band at all, which I'm guessing not..?).So, in very, very broad strokes, yes, it's sort of how a high-efficiency (class D) transmitter works... But it's missing 110% all the subtle things to make an actual transmitter: there's no coupling network, it's not filtered, it's not modulated, it can't stay in its channel... take your pick!Ed: incidentally, SMPS are over that frequency nowadays. Probably the cheaper and older models are still under 150kHz (FCC Part 15 lower threshold, so they only have to worry about levels of harmonics), but the newer and more compact types are pushing 300kHz, even low MHz with GaN FETs.Tim
What input is required in this online meter shunt calculator? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 12, 2012, 11:59:45 pm
content: I am trying to understand what input is expected when using the on line meter shunt calculator at:http://ibration.uuuq.com/Calculators/AmmeterShunt.phpI am not sure what's expected in the "Meter Full Scale Voltage Drop vA" box.Thanks.

author: IanB
author_rank: Super Contributor
timestamp: November 13, 2012, 01:07:17 am
content: QuoteIf you have a 1 mA meter that has a voltage drop of 1 V when passing a full scale current of 1 mA, and you want a shunt so the meter reads from 0 to 1 A, then you enter 1 A forI, 1000 uA forIAand 1 V forVA.

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 13, 2012, 09:34:35 am
content: Quote from: IanB on November 13, 2012, 01:07:17 amHmm, I am hopeless at the maths side of electronics (which is a big problem to me...). Let me see if I have this right, and thanks for the reply Ian.The meter has a coil resistance of 1046 Ohms. It has a 200uA full scale deflection (.0002 Amps). So to achieve a full scale deflection the meter drops 209mV?? I use .209 Volts as the figure?Not confident I have my head round this, sorry.....

author: w2aew
author_rank: Super Contributor
timestamp: November 13, 2012, 01:45:43 pm
content: Sounds right to me.

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 14, 2012, 10:01:29 pm
content: Quote from: w2aew on November 13, 2012, 01:45:43 pmThanks Alan, and thanks for the web cam info you sent, and I rudely forgot to reply to before accidentally deleting it.
what is 3d ic? - Page 1
Forum section: electronics / beginners

author: SDBFG
author_rank: Contributor
timestamp: April 24, 2018, 01:45:32 pm
content: hello siri just found 3d ic from google what does it do?

author: agehall
author_rank: Frequent Contributor
timestamp: April 24, 2018, 01:52:16 pm
content: You might want to attach some sort of link so that others can deduce what it is you are talking about. Google didn't exactly give me 1 specific answer to "3d ic"...

author: BravoV
author_rank: Super Contributor
timestamp: April 24, 2018, 01:54:01 pm
content: Quote from: SDBFG on April 24, 2018, 01:45:32 pmHow old are you ?

author: SDBFG
author_rank: Contributor
timestamp: April 24, 2018, 02:02:26 pm
content: hello siri found it from herehttps://tezzaron.com/

author: schmitt trigger
author_rank: Super Contributor
timestamp: April 24, 2018, 02:39:46 pm
content: Reading thorough their rather verbose brochure, it appears that it is a "novel" wafer-level interconnection scheme.

author: mikerj
author_rank: Super Contributor
timestamp: April 24, 2018, 02:47:56 pm
content: The web site you linked to already has a very basic, non-technical description of theprocess
What is " Q oss"  FET parameter? - Page 1
Forum section: electronics / beginners

author: fonograph
author_rank: Frequent Contributor
timestamp: November 10, 2017, 08:34:56 am
content: I am looking at FET transistor datasheet and there is list of capacitances,total gate,gate > source,gate > drain but then there is this Qoss charge with quite high capacitance,what is it? What should I think about it? When does engineer need the Qoss value? In what scenario does it become important?I am looking at two different transistors,they are very similiar,this is their capacitancestransistor 1 transistor 2QG 3.4 6.2QGS 1.1 2.4QGD 0.55 0.9QOSS 16 11.5For switch mode power supply,whitch one would you choose? Their breakdown voltage and on resistance is same.The Qoss was measured at same voltage for both of them,50V.The transistor 1 have lower capacitance across the board except much higher Qoss,I dont know what to think about it,I would like to know what that Qoss is so I can judge it and pick best transistor.

author: fonograph
author_rank: Frequent Contributor
timestamp: November 10, 2017, 09:19:48 am
content: loss? Isnt Qoss capacitance? Its measured in nano coulomb,so I thought it works like parasitic capacitance when hard switching.Does that mean that if the transistor is switched faster with more powerfull gate driver,then Qoss will be lower becose the transistor spends less time in the intermediate region between on and off?Is it like energy that will be dissipated becose of the resistance when the transistor is changing from ON to OFF? Is that it?

author: fonograph
author_rank: Frequent Contributor
timestamp: November 10, 2017, 09:34:05 am
content: ooooOOOOO I understand it! Thank you very much for explanation.EDIT : Can you tell me more about that Qoss? Where is it created? I expect it exist between source and drain,is that correct?
What is "STC32AB" (Datasheet request) - Page 1
Forum section: electronics / beginners

author: sjd.aliyan
author_rank: Contributor
timestamp: May 08, 2016, 11:05:25 am
content: Hey peopleThis is a IC from SThttp://g03.a.alicdn.com/kf/HTB1J8S6LpXXXXcHXFXXq6xXFXXXY/STC32AB.jpgI need more information about this IC and Datasheet*Notice that there is not anything about this IC in Alldatasheet and other dathasheet databeses.

author: PA0PBZ
author_rank: Super Contributor
timestamp: May 08, 2016, 11:20:34 am
content: https://www.digchip.com/datasheets/download_datasheet.php?id=928710&part-number=ST26C32AB

author: sjd.aliyan
author_rank: Contributor
timestamp: May 09, 2016, 04:54:15 am
content: Quote from: PA0PBZ on May 08, 2016, 11:20:34 amThanks manbut in the picture there is "STC" not "ST26C"

author: PA0PBZ
author_rank: Super Contributor
timestamp: May 09, 2016, 07:23:16 am
content: Quote from: sjd.aliyan on May 09, 2016, 04:54:15 amYes, I think it just doesn't fit? You can always verify if it is the correct chip by looking how it is used.

author: wraper
author_rank: Unknown
timestamp: May 09, 2016, 08:10:33 am
content: Quote from: sjd.aliyan on May 09, 2016, 04:54:15 amHave you ever heard of shortened part numbers or marking codes?ST26C, read STC. First part of the part name usually is shortened because often it is family of devices. And the second part is for actual model identification.

author: sjd.aliyan
author_rank: Contributor
timestamp: May 09, 2016, 08:38:50 am
content: Yes but i didn't think of that in this case!thanks man!

author: wraper
author_rank: Unknown
timestamp: May 09, 2016, 09:04:15 am
content: Quote from: sjd.aliyan on May 09, 2016, 08:38:50 amThen good luck finding STC32AB from STMicroelectronics without 26.

author: bitwelder
author_rank: Super Contributor
timestamp: May 09, 2016, 09:42:04 am
content: Shouldn't STMicro have some Application Note or other document where they explain their official way to mark their ICs ?

author: sjd.aliyan
author_rank: Contributor
timestamp: May 09, 2016, 11:32:16 am
content: I dont know if they have or not but it could not fit in only one file or format.soooooo many ic's,so many packages...even same ic's in different packages have different naming formats.Plus some of ST Ic's are custom built with stupid names.

author: wraper
author_rank: Unknown
timestamp: May 09, 2016, 11:38:19 am
content: Quote from: sjd.aliyan on May 09, 2016, 11:32:16 amI guess there are order of magnitude less custom built IC's than you might think.Once you go for smaller packages, there is no model number on them at all. Just some kind of obscure code. And they still are off the shelf parts in vast majority of cases.
What is "Zero power switching?" - Page 1
Forum section: electronics / beginners

author: hurricanehenry
author_rank: Regular Contributor
timestamp: October 18, 2015, 08:19:09 am
content: What is "Zero power switching?"It says that in the manual for the Weller WESD51.

author: Simon
author_rank: Unknown
timestamp: October 18, 2015, 08:21:54 am
content: maybe refers to controlling AC and operating a switch when the voltage waveform is at 0V

author: janekm
author_rank: Unknown
timestamp: October 18, 2015, 08:24:39 am
content: Or a power switch that switches the mains (drawing 0 power when off), perhaps?

author: TimFox
author_rank: Super Contributor
timestamp: October 18, 2015, 04:22:32 pm
content: It's a typo for "zero-voltage switching", where the thyristor is turned on and off only when the voltage across it is zero, to reduce EMC problems.Amusing story:I once built a simple vacuum-tube linear regulator, with a triode-connected 6Y6GA pass tube, a 6SH7 pentode error amplifier, and a 0A3 gas VR tube reference inn the cathode of the 6SH7. When first turned on, there was a high-frequency (roughly 100 MHz) parasitic oscillation that I fixed with a resistor between the plate of the 6SH7 and the grid of the 6Y6GA. Thereafter, I was paranoid about oscillation and found a strange low-level waveform on the output that was 10 Hz and line-synchronous. After trying various circuit variations (assuming an oscillation) that modified the amplitude slightly but did not affect the frequency, I unplugged my Weller soldering iron and the problem went away. Apparently, with the iron idling in the holder it went into a limit-cycle that was synchronized to the 60 Hz line by the zero-voltage switching. The very slight change in the voltage at the common power-strip connection affected the heater voltage on the 6SH7 which made a slight change in the grid voltage to affect the offset voltage at the error amplifier input.

author: hurricanehenry
author_rank: Regular Contributor
timestamp: October 22, 2015, 01:46:32 am
content: Wow interesting.I guess we can't isolate the iron, because that would defeat its electrostatic grounding feature.

author: tron9000
author_rank: Frequent Contributor
timestamp: October 22, 2015, 07:37:45 am
content: no ,not really, you can still have an isolated ironandhave an EG point on it.
What is a AJK0(or O) SOT23-6? - Page 1
Forum section: electronics / beginners

author: castingflame
author_rank: Regular Contributor
timestamp: March 12, 2019, 08:20:38 pm
content: AJK0(or O) SOT23-6. Anyone know what it is? It may be a MCP4725A0T-E/CHI need to confirm it but I am struggling.

author: amyk
author_rank: Super Contributor
timestamp: March 13, 2019, 12:08:10 am
content: Post a picture of it.For reference, attached is a picture from someone selling MCP4725A0T.

author: castingflame
author_rank: Regular Contributor
timestamp: March 13, 2019, 08:28:30 am
content: Thank you for your response amyk. Your wish is my command.Well the codes don't match to what I thought it was. It is not a million miles away though. I believe the last few letters after the forward slash are for package type and in this chip /CH denotes SOT-23.

author: castingflame
author_rank: Regular Contributor
timestamp: March 13, 2019, 09:04:21 am
content: FWIW, another 2 suppliers on AliExpress have these pictures with the MCP4725A0T-E/CH and they are different numbers again...AJEQAJ4AAnd one I ordered from Farnell is labeled AJ42They ALL have the AJ prefix though.

author: castingflame
author_rank: Regular Contributor
timestamp: March 13, 2019, 09:12:44 am
content: So far I have used;Google:All Transistors:https://alltransistors.com/search.php?search=ANK0Markings SMD:http://www.s-manuals.com/smdThe SMD Code Book:https://www.sphere.bc.ca/download/smd-codebook.pdfSMD Codes Databook: caxapa.ru/thumbs/588912/smd-codes.pdfSurface Mount package markings search:https://www.random-science-tools.com/electronics/SMD_markings.php?formtype=SMD_markings_search&search_string=AJK0The SMD Codebook (R P Blackwell):www.marsport.org.uk/smd/mainframe.htmStack Exchange SearchI emailed all my suppliers from my original orders but a lot of them are just not responding or unhelpful as they are generic sellers that do not specialise but 'box shift' their items.

author: LukeW
author_rank: Frequent Contributor
timestamp: March 13, 2019, 09:36:49 am
content: http://ww1.microchip.com/downloads/en/DeviceDoc/22039d.pdfThe MCP4725A0T-E/CH has a marking code of AJNN, where NN is some sort of variable batch code or date code."A0" denotes the address configuration (A2 and A1 both hard set to 0)T denotes tape and reel packagingE denotes -40C to +125C temperature ratingCH denotes SOT23-6 package.

author: castingflame
author_rank: Regular Contributor
timestamp: March 23, 2019, 08:47:12 pm
content: Quote from: LukeW on March 13, 2019, 09:36:49 amThank you very much for your help. Spot on.Sent from my SM-N960F using Tapatalk
What is a Child Board? - Page 1
Forum section: electronics / beginners

author: electrolux
author_rank: Regular Contributor
timestamp: May 25, 2014, 10:54:22 am
content: What is a Child Board?

author: Simon
author_rank: Unknown
timestamp: May 25, 2014, 10:59:01 am
content: It's when you have forum boards categorised so say the MCU section was categorised, each section would be a "child board" of the main section

author: amyk
author_rank: Super Contributor
timestamp: May 25, 2014, 11:56:54 am
content: Makes sense a moderator would reply about boards in a forum... but I think the OP might've been referring to PCBs, in which case a child board is a smaller board that's plugged into a motherboard.

author: Simon
author_rank: Unknown
timestamp: May 25, 2014, 11:58:05 am
content: err, motherboard - daughter board that's how I've always heared them refereed to as

author: Rerouter
author_rank: Super Contributor
timestamp: May 25, 2014, 12:13:49 pm
content: can even be used to refer to a mod board, where the designers removed an IC and fitted a pcb on legs in place to modify the function, i've seen this many times with older digital panel meters,

author: Yago
author_rank: Frequent Contributor
timestamp: May 25, 2014, 02:04:43 pm
content: Quote from: Simon on May 25, 2014, 11:58:05 amA GrandMother Board? :p

author: Simon
author_rank: Unknown
timestamp: May 25, 2014, 02:16:09 pm
content: watchit we'll be accused of sexism next....

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 25, 2014, 02:37:35 pm
content: It is the Politically Correct™ term for "daughter-board"*.* I only use the term "daughter-board" for illustrative purposes. No SEXISM should be inferred from that usage.

author: Simon
author_rank: Unknown
timestamp: May 25, 2014, 02:39:42 pm
content: Yes i was the first one to mention daughter-board, only joking
What is a differential singal for galvometer? Also check my schematic plz :) - Page 1
Forum section: electronics / beginners

author: IJK98
author_rank: Newbie
timestamp: February 06, 2023, 08:28:24 am
content: I want to control a galvometer for a laser. This link as some info about the signal input pins.https://www.aliexpress.us/item/2255800553050695.html?spm=a2g0o.order_list.order_list_main.5.54b01802imLrS8&gatewayAdapt=glo2usa&_randl_shipto=USFor each x and y, they have two input signals +IN and -IN as both -5V~+5V analog signal. So a differential signal means they can be opposite all the way negative and positive on both sides as the switch or does the +IN has to always be positive?Also is DAC8581 and MIC920 good or bad choices? Also is my schematic have any obvious mistakes or you have suggestions? The DC jack would be 16v. Also pcbway doesn't have 600k ohm resisters, so I should change that or something idk. Also I was going to use a raspberry pi for the SPI and 3.3v digital power supply.This guy already did what I wanted and explains it lol.

author: m k
author_rank: Super Contributor
timestamp: February 14, 2023, 02:18:18 pm
content: Your circuit is very staright forward and you're already checked all the values so no arguments.Maybe one timing issue.If timing is critical you can have an easier way forward with syncronized dual DAC.But I have no idea how much difference is needed before it becomes visible.Differential means that + and - are opposite towards the center.So zero difference is no signal and so negative can't be above the center and positive below.It also means that the center is virtual.Non Differential means that + and - are also away from the center, but not simultaneously.Means also that their reference point is static, it can also mean that other conduit is the reference point.One possibility is also that both conduits go constantly over the center line, but that's a constant polarity swap, against the definition and we have a special name for that, AC.Practical difference is that differential base level can be what ever when Non Differential must stay around the reference.Natural outcome is also that differential can stand disturbances much better.Receiving is also sort of identical, both are a potential difference between + and - conduit.
what is a good all round audio op amp these days - Page 1
Forum section: electronics / beginners

author: Simon
author_rank: Unknown
timestamp: October 27, 2013, 08:35:26 pm
content: What is the jelly bean op amp these days that would be used for basic preamps ect ? something like a TL071 or 82 ?

author: Monkeh
author_rank: Super Contributor
timestamp: October 27, 2013, 08:38:01 pm
content: Probably the NE5532, or a 4558.

author: Hideki
author_rank: Frequent Contributor
timestamp: October 27, 2013, 09:10:12 pm
content: There are other tests available but I find this is a good read:http://nwavguy.blogspot.no/2011/08/op-amp-measurements.html

author: Jon86
author_rank: Frequent Contributor
timestamp: October 27, 2013, 09:11:43 pm
content: Yep, 5532.

author: Lightages
author_rank: Unknown
timestamp: October 27, 2013, 09:43:50 pm
content: It is funny how that after all these years, the 553X series are still such highly useful and adequately performing devices for audio.

author: true
author_rank: Frequent Contributor
timestamp: October 27, 2013, 10:27:41 pm
content: I am using the 5532, NJM2068 and NJM4556. Lots of crap (and some good ones) in the market but these are cheap and work really well.

author: Simon
author_rank: Unknown
timestamp: October 28, 2013, 12:57:00 pm
content: ok thank you all I'll get some 5532's

author: fcb
author_rank: Super Contributor
timestamp: October 28, 2013, 01:14:12 pm
content: Good choice Simon. Most of the music you listen to will have been through a 5534/5532.

author: kc9qvl
author_rank: Regular Contributor
timestamp: October 28, 2013, 03:20:49 pm
content: For a fet input opamp the opa2134 is nice. very nice jfet input is the AD8620

author: ElectricGuy
author_rank: Regular Contributor
timestamp: October 28, 2013, 08:43:04 pm
content: My opinion;N5532LM833NOPA2134LT1213LM4532LME49720The order doesn't matter!!

author: Lightages
author_rank: Unknown
timestamp: October 28, 2013, 09:46:39 pm
content: Actually the order does matter in a sense. Some op amps are better for input voltage noise, some better for current noise. There are other parameters that matter too in certain circumstances depending on the specific application. But as a jelly bean op amp we aren't talking specific applications of course.
What is a ls-8043p electrostatic discharge board - Page 1
Forum section: electronics / beginners

author: alank2
author_rank: Super Contributor
timestamp: May 29, 2018, 02:16:02 pm
content: I think it fell out of a notebook I took apart last week. It is a small tiny little pcb 1/4" x 1/2". I don't see how it connects to something, but maybe it was just wedged or pressed between something...

author: Paul Price
author_rank: Super Contributor
timestamp: May 30, 2018, 10:13:38 pm
content: http://www.s-manuals.com/motherboard/compal_ls-8043pIt's a pcb with 2 high-voltage back to back zener's that discharges static electricity between two pieces of equipment without creating a ground loop.
What is a most suitable size/material for a big SMPS transformer ? - Page 1
Forum section: electronics / beginners

author: Refrigerator
author_rank: Super Contributor
timestamp: March 08, 2015, 11:14:08 am
content: Hey.So after my first attempt at building a welder i completely and utterly failed. The welder can barely sustain an arc and won't even weld. So i saw this inverter welder schematic ( over herehttp://all.chury721.cz/WEBY/www.danyk.wz.cz/svar_en.html) and i thought i'd give it a try. It looks simple and easy to build yet i'm not too sure about the transformer part of it.I don't have any big ferrite cores for a transformer but i have plenty silicon-iron sheets, plates and transformer cores of different sizes.I've torn apart a PC power supply and it had a silicon-iron core transformer in it, so i guess it is possible to do it.What i think of using is a small toroidal core from some rather unusual looking device.The dimensions are 25mm x 68mm x 40mm ( H x OD x ID );Here's a photo.I'd like to ask if it is possible to make a decent size SMPS transformer with silicon-iron as a core.Or do i just wind it like ir says in the schematic and hope for it to work ?

author: JohnnyBerg
author_rank: Frequent Contributor
timestamp: March 08, 2015, 11:31:30 am
content: You cannot replace ferrite with silicon-iron cores.As for the core, there are many distinctive factors. The 2 most important are form factor (like E, ET, Toroid) etc. and ferrite material. Yes, there are more different ferrites, then the colors of my wife's hair.Before making any attempt on building an SMPS, I would suggest you get familiar with the most basics of SMPS. Its not something you build with thorough knowledge of the do's and don'ts.
What is a typical diode voltage that saturates the optocoupler? - Page 1
Forum section: electronics / beginners

author: zape
author_rank: Contributor
timestamp: September 01, 2018, 01:27:01 am
content: I suspect a dead optocoupler which is supposed to switch on the power supply and diode voltage is 1v. however the Vce is ~10v

author: David Hess
author_rank: Super Contributor
timestamp: September 01, 2018, 11:06:22 am
content: The diode is normally driven by a current and the optocoupler has a CTR (current transfer ratio) where the output current is some percentage of the input current. 20% to 80% is typical for transistor optocouplers.If you want a safe value, the diode's forward voltage drop is about 1.5 volts so 5 volts applied through a 150 ohm resistor will yield 10 milliamps at the input and maybe half that at the output.

author: Zero999
author_rank: Super Contributor
timestamp: September 01, 2018, 03:24:43 pm
content: Quote from: zape on September 01, 2018, 01:27:01 amThe diode is an infrared LED, which has a far higher forward voltage, than an ordinary silicon diode, normally around double. If you're only putting 1V across the diode, then hardly any current will flow, so the transistor will be off.As mentioned above, pass about 10mA through the diode and the transistor should measure closed circuit.

author: Wolfgang
author_rank: Super Contributor
timestamp: September 01, 2018, 05:18:29 pm
content: The GaAs LED inside an optocoupler does have a turn-on voltage, but this (as Silicon diodes) varies with temperature quite a lot. Drive OCs by current not by voltage !
What is an Alternistor Triac? - Page 1
Forum section: electronics / beginners

author: Michael George
author_rank: Contributor
timestamp: October 07, 2015, 05:08:27 am
content: I know what a Triac is. I've heard about "Alternistor Triac" is it different from an ordinary Triac? or just a name?

author: Ian.M
author_rank: Super Contributor
timestamp: October 07, 2015, 05:57:17 am
content: Did you google Alternistor?

author: tautech
author_rank: Super Contributor
timestamp: October 07, 2015, 05:57:34 am
content: I've only come across them used for phase control in the primaries of welders.Quick check on Wiki confirms my understanding that they are a only 3 quadrant Triac.https://en.wikipedia.org/wiki/TRIACAlso known as High commutation (Hi-Com) Triacs
what is Analysis Bandwidth? - Page 1
Forum section: electronics / beginners

author: fonograph
author_rank: Frequent Contributor
timestamp: May 21, 2017, 03:18:49 pm
content: I was looking at the Keysight spectrum analysers and 56k $ spectrum analyser have 23k $ option to upgrade the analysis bandwidth to 85MHz.Is the analysis bandwidth a sort of window that sets the limit at how low and high freqency you can look at the same time?Does that mean that if I pay 56k for 3.6ghz analyser,I can really only analyze 25MHz at once without the upgrade?

author: fonograph
author_rank: Frequent Contributor
timestamp: May 21, 2017, 07:41:17 pm
content: I think I figured it myself,it only matters if you want to demodulate some signal,it have nothing to do with maximum sweep span.
What is better 24 Individual resistor or 6 Resistor network? - Page 1
Forum section: electronics / beginners

author: RoadRunner
author_rank: Frequent Contributor
timestamp: April 01, 2023, 07:41:53 am
content: Hello,I am designing a board that hast 24 digital lines which need to be terminated with 50 R resistor. I am planning to get these boards assembled by turnkey PCB manufacturer.My question is specifically to BOM consolidation / Manufacturing Cost. Question can be better formulated with, Should I have increase component count or one addental part to BOM.Should I have 24 Individual 0402 Resistor or 6 Individual resistor network?Would board cost more if I have 24 components vs 6 or cost of one additional type of component really matter?Board has no other use of resistor network, Board can use some of those individual 50R resistor. Space is not a issue as well, Voltage or signal integrity is also not any.Regards

author: Siwastaja
author_rank: Super Contributor
timestamp: April 02, 2023, 03:18:03 pm
content: Difference will be small anyway.If you are doing <10000, it doesn't matter.If you are doing millions of pcs, then maybe you can save $0.05 each so that it matters, but then you need to do the actual math yourself, with part suppliers and assembly house.I never bother with those resistor networks.
What is "bulk" packaging in the context of something like a QFN package? - Page 1
Forum section: electronics / beginners

author: Starlord
author_rank: Frequent Contributor
timestamp: June 29, 2018, 03:17:35 pm
content: I need to order some programmed chips from Microchip, and while I have specified parts that come in a tray, during checkout they ask if you want them in "bulk" or "tape and reel". In this context, what does "bulk" mean? I've contacted their support for an answer obviously, but they have no mention of this in their FAQ and it seems like it's just supposed to be self-evident.I mean, with resistors or switches, "bulk" just means they throw them loose in a bag. But surely they would not do that with chips. I'm thinking maybe "bulk" is a catch all for trays or those plastic tubes whatever they're called that through hole ICs come in. But then what if I specify a part on a reel for programming but select "bulk" at checkout? How then would it come packaged?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 29, 2018, 03:18:36 pm
content: Yes, they come loose in a bag. I have no clue why Microchip even offer this.

author: wraper
author_rank: Unknown
timestamp: June 29, 2018, 03:21:32 pm
content: Quote from: mikeselectricstuff on June 29, 2018, 03:18:36 pmIf you order some small quantity for prototypes, I see no reason why they would need to be repackaged into tape or whatever.

author: Starlord
author_rank: Frequent Contributor
timestamp: June 29, 2018, 03:35:48 pm
content: Quote from: mikeselectricstuff on June 29, 2018, 03:18:36 pmDo you know this from personal experience with them?I just got a response from Microchip and they claim if I order parts in a tray and select "bulk" they will arrive in the tray.

author: Bud
author_rank: Super Contributor
timestamp: June 29, 2018, 03:58:50 pm
content: Quote from: mikeselectricstuff on June 29, 2018, 03:18:36 pmSame does Digikey for Bulk option.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 29, 2018, 04:10:33 pm
content: I'm talking about SOT-23s - They have a T suffix for taped parts. Best to explicitly specify - when they go through the programming service they get repackaged, so need to spec packaging there.You want tape if at all possible - assembly houses will prefer this over trays or tube, and just laugh at you if you send bulk bags...There have been some silly glitches like they ask you to spec the basic part as 'bulk, but they have no stock showing as bulk but plenty as taped - had to contact them to sort this out to get them to use the stock they had .