hybridfree/eevblog-posts huggingface dataset:
make LTSpice simulate switching spikes? - Page 1
Forum section: electronics / beginners

author: cellularmitosis
author_rank: Unknown
timestamp: April 13, 2014, 04:24:08 am
content: Hey guys,I whipped up an ICL7660 circuit to generate a negative rail, but noticed it created significant switching spikes.I thought I'd mock it up in LTSpice so that I could try simulating the effects of ferrite beads, etc, but using an LTC1044 (Linear's ICL7660), I don't see anything that looks like a switching spike.Is there anyway to get these spikes to show up in LTSpice?

author: TerminalJack505
author_rank: Super Contributor
timestamp: April 13, 2014, 04:56:20 am
content: Are you sure what you saw wasn't just picked up by the scope's ground wire? It can act like a nice little antenna and make it look like you have switching spikes of 10mVpp to 20mVpp.Use the low inductance ground attachment (usually a spring-like thing) and see if the signal looks less noisy on the scope.Other than that you can have a similar issue where long wires on a breadboard can pick up similar noise.Also, breadboards have the issue of having a capacitive coupling type of effect for adjacent pins.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 13, 2014, 05:07:15 am
content: Try looking at I(V1), and also setting V1 for, say, 10 ohms ESR, 20nH ESL: very crudely representative of a small electrolytic.Or better yet, draw the components -- I hate that LTSpice hides all those properties from the schematic view, so you don't know at a glance what ESR/ESL you're playing with.You aren't going to get much from as soft and slow a chip as that, and depending on whether they modeled shoot-through (if any) or not.If you like, you can model your own CMOS inverter with a 2N7002 and BSS84. On a supply of about 4V or more, you'll see plenty of shoot-through, to the tune of ~20 ohms shunted across the supply for whatever the rise/fall time is. I suggest driving them from a PULSE source with, say, 10-50ns rise/fall time.It's difficult to model a realistic, representative power supply -- every wire segment or trace acts like a little inductance, and all the bypass caps interact (think vibrations on a string with beads spaced out irregularly). For best experience, do it in the real world.Tim
Make two temperature sensors read the same value - Page 1
Forum section: electronics / beginners

author: Bob Sava
author_rank: Regular Contributor
timestamp: December 03, 2020, 04:12:11 pm
content: I need two sensor inputs read the same value (value not matter much, most importantly delta needs to be 0) so I have a switch in between the two. Would below circuit work or would there be a better way?

author: Manul
author_rank: Super Contributor
timestamp: December 03, 2020, 05:10:54 pm
content: There is still no guarantee that ADC will read same value down to the LSB if that is what you want.

author: wraper
author_rank: Unknown
timestamp: December 03, 2020, 05:17:19 pm
content: You better describe what you actually try to achieve. As of now it makes no sense. You will not get exactly the same reading as no 2 sensors are completely identical. Nor your circuit is suitable for precise measurements.

author: pwlps
author_rank: Frequent Contributor
timestamp: December 03, 2020, 06:11:49 pm
content: Why two ADC ? If you want to have the same sensitivity on both sensors use a single ADC and a DPST to select the thermistor.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 03, 2020, 06:25:27 pm
content: If your ADCs are going into a microprocessor you might get best results by calibrating both systems over the operating temperature range and using a look up table to compute the same output for each when sensors are at the same temperature. By the way, making two sensors sit at the same temperature is not trivial, definitely not just a matter of letting them sit in the air near each other.A lot depends on what you mean by "same". Microdegrees? Millidegrees? 5 degrees?

author: wraper
author_rank: Unknown
timestamp: December 03, 2020, 07:22:08 pm
content: Quote from: pwlps on December 03, 2020, 06:11:49 pmMost likely this is a single ADC with multiple inputs. Switching directly connected sensors externally makes no sense. If you need average reading of two, just do averaging in software.

author: Bob Sava
author_rank: Regular Contributor
timestamp: December 03, 2020, 07:59:10 pm
content: I have a motor that takes two temperature inputs via 10k NTC - higher the delta between the two inputs - higher the motor speed. I have no way to disassemble the motor therefore I do not know if it's using two ADC inputs or multiplexes one.What I want is to be able to stop the motor from spinning remotely and knowing that when both inputs read the same temperature motor will stop (or spin very slowly) I figured I could connect both thermistors together which should result in a voltage divider that is the same for both circuits and ADC inputs.

author: Manul
author_rank: Super Contributor
timestamp: December 03, 2020, 09:40:03 pm
content: Ok, it is more clear now. I would say - try it. There could be something unexpected because of step change in temperature reading, but otherwise should work.
Make Your Own CCM Camera for Raspberry Pi Zero Module - Page 1
Forum section: electronics / beginners

author: hichm19956
author_rank: Newbie
timestamp: June 01, 2020, 03:20:55 pm
content: Hello, i'm from original has degree in chemistry, and also in ITbut i like see the small component when i was child, any wayi didn't find how interest to make similar product or inverse engineering in social media (only few likes, or someas encouragement) so i try to challenge my self, and any body how have some information about how those modules works,i try to make schematic first for ZeroCam Camera for Raspberry Pi Zero, which i count some component and guess to know them just from pics. The module it's self cost about 20$ which it's 5MP, but when i know shematic that can help to make one better using CCM from broken phone and also hight quality picture.as try i want to use OV5640 to plug it in Raspberry Pi Zero,Thank You For Reading
Make yourself a "DB107S" rectifier ?  - Page 1
Forum section: electronics / beginners

author: debi
author_rank: Contributor
timestamp: June 11, 2020, 03:47:53 pm
content: Hi guys,As a newbie i just burnt few components in my soldering station by badly replacing the heating element...I succeed to replace some CMS resistors but it looks like there is a DB107S shorted. As you may know it is a bridge rectifier and i read on internet that its possible to make you own rectifier with 4 diodes. I don't know if this is possible for a CMS rectifier as it's really small.I checked on few pcb i have at home and i didn't find any DB107S to fix it so i was wondering if is possible i make my own DB107S ?Thanks for your help !

author: exe
author_rank: Unknown
timestamp: June 11, 2020, 07:36:46 pm
content: Can you please provide some details what went wrong with your soldering station? Why do you think components are burnt?Anyway, if you are really sure the bridge is the problem, I advice just buy a new DB107S or a similar device. Like, from here:https://www.tme.eu/nl/en/katalog/?search=DB107S&s_field=1000011&s_order=desc. Or from any other distributor. Imho it's not worth bodging bridge rectifier from discrete diodes.

author: debi
author_rank: Contributor
timestamp: March 19, 2021, 03:36:17 pm
content: Hi, its been a while and i just seen your post. I didn't turn on notification at the right time. So just wanted to let you know im sorry you didn't get answer from me.. Thanks for your time. I made a ton of progress about electronics since, and the problem is obviously solved by buying the right component.Cheers !
making a 2 channel rc transmitter and reciever. - Page 1
Forum section: electronics / beginners

author: saipavan
author_rank: Contributor
timestamp: May 28, 2014, 04:02:22 pm
content: i was thinking of building an analogue 2 channel rc transmitter without using ic's such as ht12e.my first question, first is it possible to do so.then please give me a suggestion about it.
Making a battery spot welder from large supercapacitors? - Page 1
Forum section: electronics / beginners

author: electromateria
author_rank: Regular Contributor
timestamp: March 26, 2023, 02:31:39 pm
content: I have a bunch (10+) 2.7v 3000F supercapacitors.I need to weld 100 batteries for a project. Don't feel like spending $100+ on an AC spot welder if I can get away with making one real quick (and learning along the way). Generally I prefer making custom stuff and jerry rigging things over buying.What u guys think?

author: Xena E
author_rank: Frequent Contributor
timestamp: March 26, 2023, 05:53:39 pm
content: It will damage the capacitors if they are discharged instantaneously, so they're not really suitable.If you like homebrewing equipment, search for spot welder videos on You Tube... there are several designs for plant made from modified microwave power transformers!

author: james_s
author_rank: Super Contributor
timestamp: March 26, 2023, 05:59:56 pm
content: I used a bank of large regular electrolytic capacitors in mine, 22,000uF 25V parts IIRC, about 1F worth got them at a good price from a surplus place.The cheap 1F car stereo caps don't work, I tried one and it made just a few welds before failing.

author: electromateria
author_rank: Regular Contributor
timestamp: March 27, 2023, 01:18:42 pm
content: Quote from: james_s on March 26, 2023, 05:59:56 pmGot any pics of your setup? Sounds interesting.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 27, 2023, 02:25:50 pm
content: Here's a road map that I followed:https://www.philpem.me.uk/elec/welderI went a little overboard as that was years ago. It was built to solder battery tabs, which were still NiCd in those days, and fixture thin wall SS tubing for brazing. The latter was done at hgher voltage (about 22V). Tabs are done at 16V to 18V.I also tried the 1 to 4.6 F radio caps and didn't like the results. My total for the 12 smaller caps was 0.4F. The rightmost battery in the cluster picture is of a tab that I tore off to show weld strength.John
making a DIY Female-Female USB coupler? - Page 1
Forum section: electronics / beginners

author: dentaku
author_rank: Frequent Contributor
timestamp: July 28, 2015, 06:14:09 pm
content: I've been looking for a female-female USB coupler (gender changer) but can't find one locally so I cut two female connectors from an old USB hub I've never used but I have a question about the braided shielding on the outside of the cable.I checked some salvaged male USB cables that just have bare wires on the other end and the shielding isn't connected to anything but the metal part of the connector (not connected to any of the pins inside) but it's not like that on the female connectors I'm hoping to use.QUESTION: Is it strange that the braided shielding, the metalboxaround the pinsAND the black wireon these female connectors are connected together?If I want to make a F to F USB connector, can I just solder the matching wires together?I can't do anything about the black and shield being together because it seems to be connected internally.My mother got a Hyundai with a mini USB connector on the stereo so I want to make this so that a regular full sized USB flash drive can be used with it.

author: charlespax
author_rank: Regular Contributor
timestamp: July 28, 2015, 08:18:40 pm
content: Don't worry about the shielding. It's so short you shouldn't need to shield anything. Quite often in cables you'll find that the cable shielding isn't actually connected to the connector housing.GND to GND and 5V to 5V is correct. How you connect the D+ and D- may depend on your application. I believe an off-the-shelf gender changer is straight through.

author: dentaku
author_rank: Frequent Contributor
timestamp: July 28, 2015, 08:45:52 pm
content: Quote from: charlespax on July 28, 2015, 08:18:40 pmI guess what I found funny is that the USB GND (pin 4) is also connected to the connector housing internally somehow but I was comparing it to amale USB plug.I just checked a female connector and the housing and pin 4 ARE connected so I guess that's normal. On PCBs the housing is soldered to the ground plane anyway and so is pin 4

author: dentaku
author_rank: Frequent Contributor
timestamp: July 28, 2015, 10:25:12 pm
content: It works. I just connected the 4 wires together and ignored the shielding now the car can play MP3s from a USB mass storage device.Boy that stereo has a horrible interface!
making a frequency measurement meter with LCD display - Page 1
Forum section: electronics / beginners

author: khatus
author_rank: Regular Contributor
timestamp: July 22, 2019, 03:14:38 pm
content: Hello guys i am currently making a frequency meter using pic 18f4550 micro controller. Here is my code written inmikroc profor picCode:#define f_timer 2000000sbit LCD_RS at LATB4_bit;sbit LCD_EN at LATB5_bit;sbit LCD_D4 at LATB0_bit;sbit LCD_D5 at LATB1_bit;sbit LCD_D6 at LATB2_bit;sbit LCD_D7 at LATB3_bit;sbit LCD_RS_Direction at TRISB4_bit;sbit LCD_EN_Direction at TRISB5_bit;sbit LCD_D4_Direction at TRISB0_bit;sbit LCD_D5_Direction at TRISB1_bit;sbit LCD_D6_Direction at TRISB2_bit;sbit LCD_D7_Direction at TRISB3_bit;void main ( void ){unsigned long signal_period,data1,data2;unsigned long frequency_Hz;float Frequency;TRISC.TRISC2=1;OSCCON=0b1110000;PIE1.CCP1IE=1;PIR1.CCP1IF=0;CCP1CON=0x05;CCPR1=0x00;PIR1.TMR1IF=0;T1CON=0x80;TMR1H=0;TMR1L=0;T1CON.TMR1ON=1;Lcd_Init();TRISB = 0;TRISA = 0;PORTA = 0;while( 1 ){while(!(PIR1.CCP1IF));PIR1.CCP1IF=0;data1 = CCPR1;while(!(PIR1.CCP1IF));PIR1.CCP1IF=0;data2 = CCPR1;if(data1 < data2){signal_period = data2 - data1;Frequency = ((float)f_timer / (float)signal_period);FloatToStr( Frequency,frequency_Hz );Lcd_Out_Cp(frequency_Hz);while(1){}TMR1H=0;TMR1L=0;}}}The code compiled successfully.The problem is the LCD display did not show any value.Can anybody correct my code??

author: hexreader
author_rank: Frequent Contributor
timestamp: July 22, 2019, 05:08:51 pm
content: Solution already given here:https://forum.mikroe.com/viewtopic.php?f=88&t=75001
Making a Full Bridge Rectifier and grounding problems with scope - Page 1
Forum section: electronics / beginners

author: ez24
author_rank: Super Contributor
timestamp: October 20, 2015, 04:56:59 pm
content: This shows the hazard of using the ground clip on a scope. Dave has a video on why this happens. Would someone put a link to it please.

author: Len
author_rank: Frequent Contributor
timestamp: October 20, 2015, 05:39:43 pm
content: Here's Dave's video:http://youtu.be/xaELqAo4kkQ

author: DimitriP
author_rank: Super Contributor
timestamp: October 20, 2015, 06:39:33 pm
content: Or .... eevblog oscilloscope will return all of Dave's oscilloscope videoshttps://www.youtube.com/results?search_query=eevblog+oscilloscopeMuch faster than creating a post and waiting for an answer

author: Simon
author_rank: Unknown
timestamp: October 20, 2015, 08:14:56 pm
content: easy solution, if in doubt use both your channels and set them to math A-B or vice versa, that way you end up with a single channel scope with an isolated* differential input. Of course this means your sample rate is reduced to 1/2 and your memory will also be shared.*within the normal input limits of your scope

author: fubar.gr
author_rank: Unknown
timestamp: October 21, 2015, 10:18:44 am
content: I like Electroboom's videos, because he usually explains in detail the dangers of what he's doing, but here he's doing something extremely dangerous while making it look safe.Isolating the oscilloscope by defeating the ground prong is a very bad idea. If you then connect the aligator clip to the live wire, the whole oscilloscope internal metal shield, including the exposed BNC connectors at the front, will be brought to mains voltage!Simply brushing your hand against the channel connectors at the fron panel will be enough to electrocute you.
making a linear power supply safer. - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: February 21, 2020, 01:26:16 am
content: so I know the need for proper fusing and ground but that's about it, MOV's and all those other things are a mistery to me.I want to make this transformer/power supply for a tube amp safer or more reliable or anything that's usefull, benefitial and isn't like rocket science to do.[ Attachment Invalid Or Does Not Exist ]also what is the use for C6?I pretty much never seen this.also I've seen caps across rectifier diodes so is that benefitial?also I've read about putting a 625V 1650V? mov from the plates to the center tap of the output transformer.I am using EL84's with a lower plate voltage of about 380V in my case (yes I know...)and should I use like a 425v mov?

author: Vovk_Z
author_rank: Super Contributor
timestamp: February 21, 2020, 08:31:18 am
content: To it was reliable you definitely don't have to use КЦ401Б.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 21, 2020, 08:44:27 am
content: The capacitor C6 has some sense in EMI suppression and it also takes some of the magnetizing current of the transformer (this does not make much of a difference with a large transformer). It also limits the rate of voltage change and this way is a little similar to the capacitors parallel to the diodes.Tube circuits tend to use some extra filtering after the rectifier, so if a MOV is used at all the question is a little where to place it. It could well be only after the filtering - but it depends how well those parts handle overload.

author: Vovk_Z
author_rank: Super Contributor
timestamp: February 21, 2020, 09:14:51 am
content: Quote from: ELS122 on February 21, 2020, 01:26:16 am- put 100 R ... 470 R resistor in series with that capacitor, to it was fully functioning RC-snubber. Of cause, because of high voltages, here we can use serial connection of parts, for example, two serial connected 100 R 1 W resistors, two serial connected 0.01 uF 1000V capasitors (C6), etc.We can use usual power diodes here, again, for example, serial connected 1N4007, etc.
Making a 'new' charger for a camcorder - Page 1
Forum section: electronics / beginners

author: jotwerde
author_rank: Contributor
timestamp: December 18, 2018, 07:04:29 am
content: I've got an old camcorder whose charger recently stopped working. It's a pretty common 5V 2A charger.I've also got a phone charger with the same specs lying around, which I don't use anymore. The only difference between the two is that they have different connectors.So, I figured I could just cut off both connectors and solder the camcorder charger connector to the phone charger.Is there any reason why I shouldn't do this?Thanks a lot in advance.

author: Ranayna
author_rank: Super Contributor
timestamp: December 19, 2018, 08:26:55 am
content: As long as the USB supply is not some kind of "smart" charger this should work fine. A "smart" charger might rely on some kind of negotiation protocol to deliver full power.One important thing though: Do not rely on the wire colors in regards to polarity. Use a multimeter to verify polarity, and try to find documentation on how the original plug should be wired.

author: t1d
author_rank: Super Contributor
timestamp: December 20, 2018, 04:00:02 am
content: Additionally, should the replacement charger have a lower amperage rating, I believe that your charging time could be extended.Why not repair the original charger? That would be a great low-level, fun, learning project and we would be glad to talk you through it. It is most likely a very simple problem... My bet is, in order of likelihood, a bad fuse, a bad cap, or a bad diode... There are other possibilities, farther down the list...What is your interest in doing that? If you might give it a go, what is your skill level and what equipment do you have access to? Most likely you would only need a Multimeter and a solder iron/supplies.Come on, let's do it! Start by unplugging it and opening it up. Hint - Screws are often hidden under labels and rubber feet.Give it a good look, but there is no need to do anything else, yet. The problem may be readily apparent. Look for scorch marks and swollen, leaky capacitors. If you don't see the issue, we will tell you what to do next.Pictures would be most helpful, please and thank you.

author: jotwerde
author_rank: Contributor
timestamp: December 22, 2018, 07:32:33 am
content: Quote from: t1d on December 20, 2018, 04:00:02 amThank you very much, I really appreciate your nice reply!I decided to take a look, and indeed it was just a leaky cap, like you said!The charger has no screws at all and I had to pry it open with a screwdriver/pocket knife, which originally was the reason I didn't want to try to repair it (opening it was quite tough for me).However, I accidentally removed some of the white adhesive around the wires running to the connector, do I have to replace it or is this not important?

author: kjr18
author_rank: Regular Contributor
timestamp: December 22, 2018, 09:01:12 am
content: This white silicon like stuff is used to keep components from "flapping around in a breeze". Probably used to stabilize cable so it would not move too much under vibration, so they wouldn't break. If you want you could put some hot glue on it.
Making a power supply  - Page 1
Forum section: electronics / beginners

author: Craneguy
author_rank: Newbie
timestamp: March 03, 2019, 09:26:38 pm
content: Ok so I’m brand new and my knowledge of electronics is basic at best, I’m just a dumb crane op who gets paid to play with expensive toys. I had an old pyramid power supply that went belly up but the transformer, rectifier, and case is still good. The pyramid claimed to be good for 18 amps constant/20 surge. Im getting around 25 volts dc out of the recitifier so I purchased a DROK adjustable buck converter rated @15A/750W. I can fit it into the old pyramid case beautifully. I looked at some info on astron supplies and noticed they generally use 2,000 uf per load amp. So if I’m understanding all of this right I **think** I should probably use a 30,000-40,000 uf cap for a filter cap directly after my full wave bridge rectifier, which will then feed my buck converter, which will then goto my binding post and then to my load, hopefully giving me roughly 3-24 volt variable power supply capable of up to 15 amps. My main question is does this sound ok to do or am I building an electronic Molotov cocktail? If it is ok, am I in the right ballpark for the filter cap? Thanks in advance for any input/advice.

author: RES
author_rank: Regular Contributor
timestamp: March 05, 2019, 11:45:17 am
content: 1x 30000uF/40V (min. 40000uF/40V for 20A, not too large -> rectifier bridge (diodes) must be big enough to handle the inrush current at switch on (low ESR cap(s), short large charge/load on bridge diodes), or 4 x 7500uF/40V in parallel. (15A). Verify the rules of thumb for a full wave rectifier bridge power supply to be sure.

author: Eldi4
author_rank: Contributor
timestamp: March 05, 2019, 12:40:47 pm
content: I will not go into 1x30000uF choice, because the dimension would be huge (although your 20A transformer would be huge too), and if it's goes wrong you will have to buy a new one, but if you use 4x7500uF, you'll get lower ESR,and if one goes wrong you are only replacing one of them not all, and although the overall volume will pretty much same, the placement of 4x7500uF is easier and better to see.as for inrush current you can use NTC to reduce it, four of em, 2 on the ac output, and 2 on the rectified dc output.everything will goes okay as long as you connect everything correctly,linear power supply is a pretty easy build.

author: Craneguy
author_rank: Newbie
timestamp: March 05, 2019, 09:51:39 pm
content: Thank you for the advice. After some more homework and learning about esr’s I ordered 4x7500 uf caps. As for the NTC thermistors tho I have quite a bit more homework to do tho because I didn’t realize I needed 4. I thought they were only needed on the AC side of the rectifierThanks again for the help.

author: soldar
author_rank: Super Contributor
timestamp: March 05, 2019, 10:18:08 pm
content: Quote from: Craneguy on March 05, 2019, 09:51:39 pmYou don't. You only need one.

author: Craneguy
author_rank: Newbie
timestamp: March 05, 2019, 10:46:04 pm
content: That’s what I was told before as well. 1 on the AC side of the recitifier. Thanks for the input. Gonna read up on them tonight.
Making a rather tiny and non-standard QFN-ish package in Altium? - Page 1
Forum section: electronics / beginners

author: UTF_8x
author_rank: Newbie
timestamp: August 18, 2018, 01:55:12 pm
content: Hi, I'm kinda new to Altium and I'm trying to use the Silicon Labs (ZENTRI) AMW007R WiFi module, however it has a rather non-standard footprint and I can't for the love of satan figure out, how to create the footprint in Altium.Could someone please help me find an existing one or share some wisdom on how to do something so small in Altium without losing too much hair?(https://mouser.com/datasheet/2/368/Zentri_08292016_AMW-1203565.pdf)//EDIT: Added a STEP model of the component for reference...

author: Ranayna
author_rank: Super Contributor
timestamp: August 18, 2018, 06:48:56 pm
content: I do not know a thing about altium, and have not looked at the STEP file.But can that datasheet possibly be correct in regards to the footprint? Measurements in thousands of an inch, i.E. mils, or 0.025 milimeters? That would make the whole thing just over 0.3 millimeters wideOne has to wonder where else the datasheet is incorrect...
Making a simple transistor in LTSPICE for calculations  - Page 1
Forum section: electronics / beginners

author: John B
author_rank: Frequent Contributor
timestamp: April 13, 2020, 04:46:37 am
content: I'm trying to create a simple NPN/PNP model in LTSPICE for some circuit exercises. Basically, I'm trying to model a fixed Vbe drop on the base connection, then create a behavioural current source on the collector, which will be a function of the current flowing through the base multiplied by the beta.I used "bi" behavioural current source with the value I={I(Rb)*100}, where Rb is a 1m resistor on the base as well to sense current. Not sure if LTSPICE would accept I(Vbe). However I get the error message:Timestep too small; initial timepoint: trouble with node "n002"Im guessing it can't resolve an initial value for the current source?

author: John B
author_rank: Frequent Contributor
timestamp: April 13, 2020, 05:23:03 am
content: I think I solved...the expression should be I={I(Vbe)}*100 (or whatever beta you want)

author: Ian.M
author_rank: Super Contributor
timestamp: April 13, 2020, 07:49:02 am
content: Nope. {} braces tell the LTspice expression evaluator to do parameter substitution prior to the simulation run. You certainly don't want them round the varying expression controlling the 'bi' behavioural current source. Also, behavioural sources can be computationally expensive and are prone to convergence problems, so for a linear relationship its preferable to use an 'f' source (linear current controlled current source), which uses a named voltage source as the current measurement point. In its attribute editor, set Value to the name of the voltage source, and Value2 to the fixed multiplier.Also if you don't want the model to fail ludicrously if the voltage driving the base circuit is less than your 0.7V Vbe, or if the base current is too large for the available collector current, you'll have to add some ideal diodes, one in series with the base, to prevent negative base current, and the other across the 'f' current source, cathode to the collector to prevent it taking the collector negative of the emitter.N.B. LTspice really doesn't like simple diodes with 12 or more orders of magnitude between Ron and Roff. Pick your Ron and Roff for an 'ideal' diode model carefully.Over-simplified fixed Vbe and gain transistor model sim attached - not fit for use for anything more advanced than checking back of the envelope designs and school STEM homework! Its not packaged as a proper SPICE subcircuit model, as I don't want to encourage its general use without explicit understanding of its deficiencies.
Making CAN BUS Fault-tolerant transceiver? - Page 1
Forum section: electronics / beginners

author: symbianas
author_rank: Regular Contributor
timestamp: April 03, 2023, 11:49:08 am
content: Hi, I have not found any pre-made "CAN BUS Fault-tolerant transceiver" module on ebay/aliexpress to buy so I am thinking to make my own. I have disassembled few car modules which have this transceiver, they are using TJA1054 chip. Also they have some additional components: one module seems to haveCommon Mode Filtersand another module seems to haveData and signal line chokes:orMy question is: Are these "Common Mode Filters/Data and signal line chokes" mandatory? Can I use transceiver without them?I have found a simple circuit on the internet it seems not to have those components:Would it work ok?

author: ataradov
author_rank: Super Contributor
timestamp: April 03, 2023, 04:13:23 pm
content: They are not mandatory for operation, but they may be necessary to meet your system fault tolerance requirements.You need to compare the level of tolerance the transceiver provides with your requirements. Most practical systems would use some sort of additional filtering.
Making inductors! - Page 1
Forum section: electronics / beginners

author: yada
author_rank: Frequent Contributor
timestamp: April 30, 2017, 12:53:14 am
content: Someone found this awesome site:http://hamwaves.com/antennas/inductance.htmlI entered inD= 0.64mm for 22ga wire Mean diameter of the air core coil, measured from wire centre to wire centreN= 5Number of turns?= 45 mmLength of the coil, measured from the connecting wires centre to centred= 4 mmWire or tubing diameter455mhz design freq.Calculator says: 0.00003348976658323965uHQuotewas blank forQuoteThat's 0.03348nH?Seems too lowThat's for NTE red coated magnate wire. Is there a chart for air core inductors?

author: yada
author_rank: Frequent Contributor
timestamp: April 30, 2017, 01:07:36 am
content: By doubling the turns to ten and wire length to 85 (80 for coil and 2.5 for each lead) it says: 0.00039868078615111344uH,So TEN times the inductance for double the length and turns?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 30, 2017, 01:42:29 pm
content: You entered a coil made ofcopper tubingwith awigglesmaller than its width -- this can hardly be called a solenoid winding!Check the drawing closely and then enter the values correctly.Tim
Making measurements on an unknown transformer - Page 1
Forum section: electronics / beginners

author: iampoor
author_rank: Frequent Contributor
timestamp: November 04, 2015, 07:57:30 pm
content: HiRecently I got some Macom PS1517 Power supplies. These were used for Video Gear. Of course, I cannot find ANY info on the rated output current or even what a few of the rails on the transformer are rated at (I know it has +-24v rails, but a few are unlabeled).I was thinking of reverse engineering the Power supply Boards (each rail has a seperate board, they are just paralleled 2n3055's as series pass transistors) to figure out an approximate current output. Are there any other ways of getting a ballpark figure? It has a 4 amp circuit breaker on the input. I was also thinking about maybe running it no load and then seeing where the voltage drops at a particular current, but thats probablly not a very useful metric without any other detail.TLDR: Figuring out the voltages is easy, but how can I figure out the approximate output current of each winding?

author: AF6LJ
author_rank: Unknown
timestamp: November 04, 2015, 08:18:57 pm
content: The wire size will give you a little clue so will the core cross sectional aria.

author: Ian.M
author_rank: Super Contributor
timestamp: November 04, 2015, 08:36:25 pm
content: You only need to reverse engineer the power circuit, not the control system. You could check voltage drop across each 2N3055 and work out the dissipation, + measure the heatsink temperature increase Also, do not exceed 10% drop from unloaded at the transformer's secondary.

author: AF6LJ
author_rank: Unknown
timestamp: November 05, 2015, 01:27:57 am
content: What He Said.

author: iampoor
author_rank: Frequent Contributor
timestamp: November 14, 2015, 09:07:31 am
content: Got some info, it is a 280va transformer....its a good start.Quote from: Ian.M on November 04, 2015, 08:36:25 pmI will be back with a schematic shortly. Great ideaQuote from: AF6LJ on November 04, 2015, 08:18:57 pmIf only it didnt have 6 windings..

author: MagicSmoker
author_rank: Super Contributor
timestamp: November 14, 2015, 03:01:01 pm
content: If you have a decent selection of power resistors you can try loading down each secondary (one at a time) until the voltage drops by 3-5%; that will usually give you the full load current rating for that secondary.A helpful site to reference on sizing unknown transformers in general:http://www.smoke.com.au/~ic/ham/transformers/used_transformers.html
making mppt solar controller with ardrino and making it upgradeable - Page 1
Forum section: electronics / beginners

author: npicot2304
author_rank: Newbie
timestamp: August 21, 2015, 09:04:57 pm
content: Hi allnow i am currently in the process of making my own 12v solar charging station for my shed (lighting inside and outside at this stage), the only thing i am missing at this present stage is the charge controller as i don't really want to buy one of those cheap Chinese controllers that say they are MPPT but are not and in fact PWM as i am sort of pushing the boundary's of battery capacity. so after doing a bit of reading on a few websites including instructables i seen that someone had created a MPPT solar controller using the arduino uno but the system could only handle 50w max so what i am wondering is, is there anyway that i can make it handle more current then that or am i waisting my time by trying to create ithere is the website that i have been looking athttp://www.instructables.com/id/ARDUINO-SOLAR-CHARGE-CONTROLLER-Version-30/the other thing is that the reason i went with the arduino MPPT solar controller is i want to be able to upgrade it when i needed as well as learn a lot more about microcontrollers.......hope i have put this in the right section
Making my own own analog RGB cable - Page 1
Forum section: electronics / beginners

author: Legion
author_rank: Frequent Contributor
timestamp: June 01, 2014, 03:45:47 pm
content: I'd like to make my own RGB cable for my Sega Master System. It goes from an 8 pin DIN to 4 BNC and 2 RCA. I can't directly solder 4 coaxial cables directly to the DIN connector as the cables are too bulky. What's the best way to solder all those cables to the DIN plug without introducing a lot of noise or interference to the signal?

author: SeanB
author_rank: Super Contributor
timestamp: June 01, 2014, 03:58:17 pm
content: Kill a cheap VGA cable and use the 3 shielded inner cables for the RGB and leave the other 2 to use the outer shield. That should be thin enough to fit in the connector if you use a thin cable, and the other end can go into a bigger box to joint to either BNC and RCA sockets or just to join to thicker shielded cables.

author: Richard Crowley
author_rank: Super Contributor
timestamp: June 01, 2014, 04:01:18 pm
content: Use smaller coaxial cable. You may have to get a consumer RGB cable and chop the RCA connectors off the Sega end.
Making my own portable music player - Page 1
Forum section: electronics / beginners

author: skyjumper
author_rank: Regular Contributor
timestamp: April 15, 2015, 03:54:06 am
content: Hi All...I have been thinking of making my own portable music player that can drive headphones or connect to a car or sound dock via bluetooth. I would also like it to be small.Looking around, I see there are a few chips that are basically music players all by themselves. Just feed data via SPI. for example: the VS1053B:https://www.sparkfun.com/products/8892Thing is, this chip is (1) relatively expensive, (2) relatively large and (3) seemingly unavailable other than from SparkFun or AdaFruit. I can't find it on Mouser or DigiKey. The big advantage is that it supports a pile of music formats and can even drive ear buds. A circuit with this chip would be straightforward.So I'm wondering, in general, how do portable music players work? Do that have an ASIC like this VS1053B or do they use something like a generic, inexpensive processor with DAC an opamp?I would like to keep it small and jam in a battery with wireless charging, BT and possibly wifi, some memory, a boost regulator and of course the music circuitry. And of course a processor to move the data and do a bunch of other things. I would omit a display and buttons and control the entire thing via a phone app.So is a dedicated CODEC the way to go, or, since I need a processor anyhow, is it better to let the uC do the decoding?Thanks for your comments...

author: marshallh
author_rank: Unknown
timestamp: April 17, 2015, 01:27:54 am
content: All current PMPs are some 16/32bit microprocessor running code. That decoder chip you linked is probably just a particular microcontroller with onboard maskrom.You can do the same by running libmad or some other fixed point decoders on a Cortex-M3.

author: skyjumper
author_rank: Regular Contributor
timestamp: April 17, 2015, 07:52:46 am
content: Quote from: marshallh on April 17, 2015, 01:27:54 amWell VLSI Solution seems to make a number of chips specific to playing and recording digital audio, including circuitry right on the chip to drive the ear buds.But, it seems if I were to use a CORTEX-M3 I could get one with 2 DACs, one for left and one for right... Would each DAC output then go to an op amp to drive the earbuds?
Making PCBs that slot edgeways into a connector - Page 1
Forum section: electronics / beginners

author: seanspotatobusiness
author_rank: Regular Contributor
timestamp: June 07, 2020, 07:15:07 pm
content: You know PCBs that slot edgeways into a connector, like PC computer memory, the BBC Microbit and the Raspberry Pi Compute module? What is that kind of edge on a PCB called? If I wanted to make a PCB like that with a service like JLCPCB or PCBway, do I just put a bunch of adjacent pads right across the edge of the board? Thanks.

author: pickle9000
author_rank: Super Contributor
timestamp: June 07, 2020, 08:06:22 pm
content: edge card connector

author: Siwastaja
author_rank: Super Contributor
timestamp: June 07, 2020, 08:39:15 pm
content: For long-term reliable operation, they need special kind ofthickgold plating, which is expensive. Basically they use some tape to mask away areas not to be plated, then dip it in the plating solution. This process is much more expensive than the standard ENIG gold plating (which you get as a basic service nowadays). I think PCBWay can do this.ENIG is too thin to handle many insertions. HASL isn't chemically stable enough. But for a prototype one-off for testing, just put bunch of pads across the edge, it will work during prototyping just fine but don't be surprised if it fails after 100 insertions, or after 5 years of sitting on your shelf.

author: bitter_mike
author_rank: Contributor
timestamp: June 07, 2020, 10:18:15 pm
content: To add to Siwastaja's point, the plating is both thicker and metallurgicaly different. It is so called "hard gold", alloyed with a bit of cobalt or nickel which enables it to last many insertion cycles. ENIG produces a pure gold deposit which is quite soft (and extremely thin).

author: free_electron
author_rank: Super Contributor
timestamp: June 07, 2020, 10:26:13 pm
content: correct. You need hard gold and a chamfered edge !That also requires to design a shorting bar. hard gold is electrically deposited so all the connector fingers need to be shorted with a trace. That trace is then milled away when they do the chamfering of the edge.There are some rules that need to be followed. your board fab will give those to you. They can typically insert the shorting bars for you. They will give you the criteria of how far the connector fingers need to retract off the edge of the board.

author: JLCPCB Official
author_rank: Regular Contributor
timestamp: June 09, 2020, 04:57:56 am
content: Hello ;These are "Gold fingers" the gold-plated columns along the connecting edges of printed circuit boards and this is available at JLCPCB production service and you can find more details about how to create it in your PCB through the following link :https://jlcpcb.com//quote/pcbOrderFaq/Gold%20Fingers?_ga=2.151270713.1815762331.1591677796-1865388022.1590056196&_gac=1.238248500.1590149276.EAIaIQobChMIh-u507fH6QIVg_hRCh2UlwvREAAYASAAEgI75_D_BwE
Making RCA cables, but where do I get cable (solved) - Page 1
Forum section: electronics / beginners

author: klausman
author_rank: Regular Contributor
timestamp: April 12, 2025, 09:40:16 am
content: Ok this one is probably really dumb, but....For various reasons I am trying to make a bunch of custom (lengths, plugs and sundry) RCA cables. That is, 2x RCA plug on at leas one side. And the cable in between should be two coax leads stuck together. Nothing super fancy (I'm not an audiophile).But it seems I can't find such cable (by the meter, not ready-made with plugs) at Digikey, Mouser or any of the local bandits. I can find the right wire as _single_ wire, but I am not keen on trying to bundle two of those "somehow" because that decidedly will be messy. I am clearly missing a magic keyword here. Or something else. What might it be?Solved: I just found the right German term to find what I need: "Meterware" aka "by the meter"

author: themadhippy
author_rank: Super Contributor
timestamp: April 12, 2025, 11:14:21 am
content: the other magic incantation that may help narrow things down is "figure 8 screened "

author: tooki
author_rank: Super Contributor
timestamp: April 12, 2025, 01:23:35 pm
content: Quote from: klausman on April 12, 2025, 09:40:16 amDiodenkabel Meterware is what you’re after.
Making sense of wire gauge tool markings - Page 1
Forum section: electronics / beginners

author: piguy101
author_rank: Regular Contributor
timestamp: March 25, 2018, 04:51:55 pm
content: I am looking at one of these circular tools to measure wire gauge.https://www.ebay.com/itm/Stainless-Steel-1-36-Round-AWG-SWG-Wire-Ruler-Gauge-Diameter-Measurer-Tool-J/401465997099?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649However, I cannot determine what the marking means from the picture. Is it AWG, SWG?Also, the back side of the tool has corresponding markings. For example, gauge 0 wire is marked as .3125. What does this mean?Thanks

author: Bratster
author_rank: Frequent Contributor
timestamp: March 25, 2018, 05:56:36 pm
content: I'm pretty sure that's a tool for measuring sheet metal thickness, with one side being the thickness represented as gauge, and the other side is in inches.I think the seller just has a bunch of generic terms.The distance being measured is between the two flat parts, not the hole.Sent from my Nexus 6 using Tapatalk

author: mmagin
author_rank: Frequent Contributor
timestamp: March 25, 2018, 06:04:52 pm
content: That's definitely sheet metal gauge:https://en.wikipedia.org/wiki/Sheet_metal#Gaugecompare withhttps://en.wikipedia.org/wiki/American_wire_gauge#Tables_of_AWG_wire_sizesAren't standards wonderful?If you're not needing to measure wire quickly, I'd just get yourself a decent caliper and look up in a table. Soon you'll find yourself measuring everything with calipers and wondering how you ever lived without them

author: Jwillis
author_rank: Super Contributor
timestamp: March 25, 2018, 06:19:24 pm
content: One side is equivalent inch scale of the other side SWG (Standard wire Gauge) scale.AWG is not interchangeable with SWG.Why they put AWG in the description is unknown. For example AWG 36 =0.00500 inches where as SWG 36 =0.007The image below is a sheet metal gauge

author: piguy101
author_rank: Regular Contributor
timestamp: March 26, 2018, 12:35:03 am
content: Thanks all! It definitely must be sheet metal gauge, which is disappointing to me. I can go with calipers for measuring the wire diameter then.

author: Cerebus
author_rank: Super Contributor
timestamp: March 26, 2018, 01:30:48 am
content: Quote from: mmagin on March 25, 2018, 06:04:52 pmIt's neither really.It's in theright formfor a wire gauge (you put a wire through a hole and try and pull it out through the slot, when it just pulls out that's the right size) but its got thewrong numbers. It's marked in US sheet metal gauge, not a wire gauge like AWG or SWG (the obsolete Standard Wire Gauge BS 3737:1964, which is the old Imperial British sizing, now metricated).SWG isnotthe same as American sheet metal gauge, it's close-ish, but it's not the same, I mistake I see repeated regularly. Because of the huge confusion that abounds between all the different gauge systems Istronglyrecommend people to always quote things by actual size and only put gauge numbers as a secondary indication and to always qualify gauge numbers if they do quote them (e.g. gauge 12 to ASTM sheet metal standards).
Making something a bit like a DAC, high currents, high speeds, 3 output levels? - Page 1
Forum section: electronics / beginners

author: Infraviolet
author_rank: Super Contributor
timestamp: February 19, 2023, 09:51:28 pm
content: Ok, I'm wondering about the possibility for a circuit element involved in an optical communication emitter which can serve to produce the following "truth table":InputA | InputB | Output-------------------------------High | High | VccHigh | Low | Vcc/2Low | High | Vcc/2Low | Low | 0So it is effectively adding the two signals.I also want it to be able to handle fairly large output currents, up to 1A, so typical op amps are out of consideration i think.Input currents would ideally be minimal, but could get as high s 10mA each if really needed.And operate for fairly fast signals, input square waves in the 5Mhz to 50MHz range, where the output isn't hugel distorted by massively extended rise times. Again this probably prohibits normal op amps from being used.What would be my options for such a circuit?Thank you

author: BrianHG
author_rank: Super Contributor
timestamp: February 20, 2023, 12:13:34 am
content: Use an analog switch like 74HC4051 or 74HC4052 to select your output voltages from a 1 of 4 or 8 inputs.Take the output to drive the input of a cheap >1amp output linear opamp in voltage follower mode.You may need to supply the opamp's VCC with a greater voltage than VCC to get the full +VCC output at 1 amp, even maybe so if it is a rail-to-rail output opamp. Digikey has a cheap 1.5amp op-amp, but, it only offers 12Mhz bandwidth.Since I do not know where you derive the 1/2 vcc, or how you load the output, there may be better solutions for your design, however, my above solution allows for setting any 4 or 8 input voltages you like.Done right, even 2x NPN transistors in emitter follower mode to buffer the 74HC4051's output with an added boost to your VCC reference could deliver a few good amps.If you need push-pull, then think about a class A-B transistor output. Again, the class AB voltage follower will need an at least VCC+1 to +2v, and a -1 to -2 volt supply for clean sharp edges, but you will find this way you can drive fast square waves to 100MHz with a good complementary pair transistors.

author: Infraviolet
author_rank: Super Contributor
timestamp: February 20, 2023, 01:26:33 am
content: Thanks, that makes sense as a principle.