hybridfree/eevblog-posts huggingface dataset:
Troubleshooting power supply converter PCB - Page 1
Forum section: electronics / projects

author: shamooooot
author_rank: Regular Contributor
timestamp: August 25, 2025, 08:04:49 pm
content: Hello GuysI have made a PCB based on the TPS65130 for an adjustable positive and negative power supply. After installing the components and testing the PCB I am getting strange results.When DAQ output = 4.93 Vneg= 3.3v, 2.4v with load Vpos= 5v, 4.6v with loadWhen DAQ = 0 Vneg= 3.3v Vpos= 4.9v, 4.6v with loadThe FBN= 1.72 and the FBP= 1.13.I have tested everything and tried multiple IC's and I am getting the same result.https://www.ti.com/lit/ds/symlink/tps65131.pdf

author: mtwieg
author_rank: Frequent Contributor
timestamp: August 27, 2025, 11:36:19 am
content: So you're saying the DAC outputs aren't affecting either Vout at all?Those observed voltages definitely don't make sense based on your schematic. When the controller is operating normally, FBP should be at 1.21V, while FBN should be at 0V.I would first simplify the circuit by removing all the extra circuitry for adjusting Vout (or just remove R2 and R12). Just make sure you can get it to operate normally before introducing the extra complexity. But beware, with those 100K/3.9K feedback dividers, this will result in Vout being +/-32V. I'm guessing that's much higher than you want (based on the 25V rating on the caps in your schematic, that is).If you can confirm it works with feedback, then I can suggest some much simpler circuitry for implementing the adjustments (which don't require a the charge pump to generate a negative rail).

author: shamooooot
author_rank: Regular Contributor
timestamp: August 27, 2025, 03:14:51 pm
content: Quote from: mtwieg on August 27, 2025, 11:36:19 amThank you very much for your reply.I did try and removed R2 and R12, I get on the positive feedback around 1.1V and around 0V on the negative feedback pin..

author: mtwieg
author_rank: Frequent Contributor
timestamp: August 28, 2025, 01:13:42 pm
content: Quote from: shamooooot on August 27, 2025, 03:14:51 pmOkay, are the Vout close to +/-32V? Can you verify they are stable with an oscilloscope?What sort of adjustment range are you aiming for?
Troubleshooting Tips - Page 1
Forum section: electronics / projects

author: amar
author_rank: Contributor
timestamp: April 16, 2013, 05:02:52 pm
content: Hi .please suggest me basic tips for Troubleshooting the circuit.

author: Bored@Work
author_rank: Super Contributor
timestamp: April 16, 2013, 05:05:36 pm
content: The circuit?

author: c4757p
author_rank: Super Contributor
timestamp: April 16, 2013, 05:07:05 pm
content: Experience. The way you go about troubleshooting The Circuit depends completely on what sort of circuit it is and what the problem is. I can't think of a single general troubleshooting tip other than "understand the circuit".

author: Bored@Work
author_rank: Super Contributor
timestamp: April 16, 2013, 05:09:32 pm
content: Ah, THE Circuit, of course.

author: DavidDLC
author_rank: Frequent Contributor
timestamp: April 16, 2013, 05:27:22 pm
content: Very generic:- Isolating the problem to a specific module or part.- Try to understand the operation of this isolated module/part.David.

author: Neilm
author_rank: Super Contributor
timestamp: April 16, 2013, 05:48:33 pm
content: Quote from: c4757p on April 16, 2013, 05:07:05 pmI would add understanding the trouble with the circuit. I can't count the number of times I have to remotely fault find a circuit when the sum total of the trouble shooting information I have had was "It doesn't work"Neil

author: bradleytron
author_rank: Regular Contributor
timestamp: April 16, 2013, 06:01:02 pm
content: You may want to get a copy of, 'Troubleshooting Analog Circuits' Robert A. Pease, NewnesB

author: mrflibble
author_rank: Super Contributor
timestamp: April 16, 2013, 06:57:37 pm
content: Quote from: bradleytron on April 16, 2013, 06:01:02 pmI concur, very nice little book.

author: w2aew
author_rank: Super Contributor
timestamp: April 17, 2013, 01:13:34 am
content: Quote from: amar on April 16, 2013, 05:02:52 pmThat's all the detail you're going to give us?The generic basics are:- study the circuit to understand how it is supposed to work- measure/verify supply voltages- isolate what works and what doesn't / divide and conquor- trace signals- measure/verify control signals- measure bias voltagesetc, etc, etc...
TRS80 model MC10 on FPGA board - Page 1
Forum section: electronics / projects

author: Dukov Ahzrukhal
author_rank: Regular Contributor
timestamp: May 15, 2019, 09:14:34 pm
content: Hello everyone, I wanted to share my TRS80 project which I just got working. This project started out as my final project for a digital system design class but it had a small issue that took me a long time to fix.I used a cheap FPGA board from ebay for the main system and a PIC16C65 MCU for the keyboard controller. I hope someone finds this fun or useful.
True RMS and Duty cycle calculation - Page 1
Forum section: electronics / projects

author: rrn
author_rank: Newbie
timestamp: December 03, 2021, 04:03:35 am
content: Can someone help with calculating modified sine wave true RMS value and also how to Control PWM dutycycle to maintain fixed output.Example: input volatge 100Vdc.Need to maintain fixed Vrms 50VACFrequency = 50hzModified sine wave same as in the picture

author: gcewing
author_rank: Regular Contributor
timestamp: December 03, 2021, 07:22:00 am
content: For PWM with duty cycle d,Vrms = sqrt(d * Vin**2) = sqrt(d) * Vinsosqrt(d) = Vrms / Vinord = (Vrms / Vin) ** 2So for Vin = 100V and Vrms = 50V, you want d = 1/4.The frequency doesn't come into it.
True RS-232 Transceiver MAX3232 works only when input has resistance - Page 1
Forum section: electronics / projects

author: luca0074
author_rank: Contributor
timestamp: September 14, 2021, 09:57:08 am
content: I discovered something as developing a handheld device.My RS232 Transceiver MAX3232https://www.maximintegrated.com/en/products/interface/transceivers/MAX3232.htmldoes only work, if i put a resistor between the input TX and RX line.The connection is directly from MAX3232 Pin 11 & 12 to SAMD51 Pin PB30 & PB31 (https://www.microchip.com/en-us/product/ATSAMD51J20A).There are no other components on the RX/TX lines.When i connect 11 to 12 (RX to TX) via a 22k ohm resistor, the RS232 connection works.I couldn't find any references regarding that there is a resistor needed.i also opened a supportcase at Maximintegrated and will post their answer here, when i receive it.

author: mikerj
author_rank: Super Contributor
timestamp: September 14, 2021, 10:31:34 am
content: Why do you have the T1IN pin on the MAX3232 connected to a net labelled RX, and the R1OUT pin on the MAX3232 connected to a net labelled TX? If your net names reflect the SAMD51 pin functions then you have these two pins swapped.

author: luca0074
author_rank: Contributor
timestamp: September 20, 2021, 11:54:01 am
content: Quote from: mikerj on September 14, 2021, 10:31:34 amHmmmi swapped the pins and now it works as intended.thank you!case closed.
True sine wave inverter waveform and analogue scope - Page 1
Forum section: electronics / projects

author: G7PSK
author_rank: Super Contributor
timestamp: July 03, 2018, 05:23:44 pm
content: I tried to look at the waveform of a true sine wave inverter with an analogue scope, but found that I could not get it to trigger correctly or lock in sync once I set the trigger to auto.Could this be due to the compound nature of the wave form.The out put of the inverter is 230 volts and 50hz when measured with a fluke meter.

author: 001
author_rank: Super Contributor
timestamp: July 03, 2018, 09:05:35 pm
content: Try inductor in series

author: jbb
author_rank: Super Contributor
timestamp: July 03, 2018, 10:49:19 pm
content: There might be heaps of HF content, so you could also look for ‘Noise Reject’ or ‘Noise Filter’ or ‘HF Filter’ or similar in your trigger options.

author: G7PSK
author_rank: Super Contributor
timestamp: July 04, 2018, 07:54:50 am
content: Thanks for the advice, there was indeed a lot of HF noise on the waveform and thousands of little steps in it.

author: jbb
author_rank: Super Contributor
timestamp: July 04, 2018, 09:18:48 am
content: Sounds about right; they often use a switch mode chopper and some LC filtering.

author: G7PSK
author_rank: Super Contributor
timestamp: July 04, 2018, 02:34:01 pm
content: This one is supposed to be a sine wave oscillator and amplifier. There are certainly a couple of sub boards inside but as of yet I have not pulled it all apart.

author: jbb
author_rank: Super Contributor
timestamp: July 04, 2018, 07:33:45 pm
content: Quote from: G7PSK on July 04, 2018, 02:34:01 pmIf you do pull it apart, be careful: there may be voltage hiding in large capacitors.

author: G7PSK
author_rank: Super Contributor
timestamp: July 04, 2018, 08:19:25 pm
content: Am aware ot that and have a capacitor discharge unit.
Trueposition GPS Board - NMEA? - Page 1
Forum section: electronics / projects

author: cherokeesix
author_rank: Newbie
timestamp: January 22, 2020, 05:50:17 pm
content: Does anyone know if the Trueposition board can output NMEA sentences?

author: texaspyro
author_rank: Super Contributor
timestamp: January 23, 2020, 07:12:33 am
content: No, I don't think it can. The messages it sends are close to NMEA format, but with different data. Lady Heather does have a feature that can echo (to another serial port) various device data formats as NMEA data.

author: cherokeesix
author_rank: Newbie
timestamp: January 23, 2020, 05:44:38 pm
content: Thanks for that - based on the lack of any viable threads of trueposition + nmea, was beginning to conclude that.I have a use for 10 cheap GPSDO's with 10MHz/1PPS and NMEA - was hoping this board would work. The LH solution is an option, but is overkill to use LH as a protocol convertor, in my use case.thanks!Dave

author: cherokeesix
author_rank: Newbie
timestamp: January 27, 2020, 12:23:41 am
content: An update - the TruePosition Board DOES output NMEA from the Furuno GT-8031 GPS module - via pin 6 on the RS232 header. They conveniently provide the output from the GPS module!I only need the GPGGA string for tod - and it also seems to have the GPGSV sentence, and more, according to the Furuno GT-8031 Protocol Specification manual:www.ko4bb.com/manuals/71.194.200.75/Furuno_GT8031_Protocol_Specification_Rev1.pdfYou still need to interact with the board via the serial port to get the board running via $PROCEED. I added the jumper across 4-5 since it was more convenient for me to use RS232.Thanks Dave

author: Mikkos
author_rank: Newbie
timestamp: December 23, 2020, 12:00:58 am
content: Dave, did you have to do anything specific to enable the NMEA stream on the pin-6 of the RS232?I'm trying to make it work on my TruePosition board, and I don't get NMEA output on that pin (pin-6 on J3).Instead, on that pin I get "echoed" copy of what I send in on the TTL port (for example sending the $PROCEED).Mikko
TrueTime XL-AK 600-00 : 10 Mhz - Page 1
Forum section: electronics / projects

author: comsec22
author_rank: Contributor
timestamp: May 09, 2023, 06:21:42 pm
content: I would like, to use an internal high quality 10 Mhz TCXO, or better modify to have a GPSDO..I know ho to set jumper and configuration commands.. What about wiring ?Any help is really appreciate.73's IU0CIX
TrueTime XL-AK 600-00 : GPS need firmware update - Page 1
Forum section: electronics / projects

author: comsec22
author_rank: Contributor
timestamp: May 08, 2023, 09:04:31 pm
content: Without LCD and front panel keyboard.. really hard to manage this GPS..I will try to manage using com port..In the mean time, TrueTime TCU, show week rollover issue.Any help to update GPS's firmware ?Cheers
TrueTime XL-AK 600-00 : Options - Page 1
Forum section: electronics / projects

author: comsec22
author_rank: Contributor
timestamp: May 14, 2023, 01:35:40 pm
content: I found the right pin to inject an external 10 Mhz standard (pin F + Gnd) moving JP6 by 2-3 to 2-1..when i try to give serial command F07 :ERROR 05 NO SUCH FUNCTION.External Oscillator Enable, is one of the several options, is it any possible way to enable ?Perhaps is the firmware in eeprom..F18 : TRUETIME XL ACE3 sys ver 029 GPS-XL V1.046 182-6064v007Any supports is welcome.

author: barshatriplee
author_rank: Regular Contributor
timestamp: May 14, 2023, 02:31:52 pm
content: It's possible that the F07 command is not available on your Tektronix TDS 524a oscilloscope, which is why you are getting the "ERROR 05 NO SUCH FUNCTION" message. I think you should contact Tektronix technical support:https://www.tek.com/en/support/contact-technical-support

author: comsec22
author_rank: Contributor
timestamp: May 14, 2023, 07:40:18 pm
content: barshatriplee..The topic is related to a TrueTime GPS not to a Tektroniks scope..
TRUETIME XL-DC and the Lady Heather app. - Page 1
Forum section: electronics / projects

author: NA5B
author_rank: Contributor
timestamp: March 05, 2024, 06:08:55 pm
content: Hello all, I would like to use the Lady Heather app with my Truetime XL-DC but it is not listed in the supported devices. I tried all the commands listed for various devices. Anyone running the Lady Heather app with Truetime XL-DC? I see that Texaspyro has a picture shared here using the same unit with the software. I also have a Fei-Zyfer Nanosync and have no problem running it with the Lady Heather using /rx3 command. Thank you.
Truly transparent HDMI switch (2:1)? - Page 1
Forum section: electronics / projects

author: Jef06
author_rank: Newbie
timestamp: April 14, 2025, 08:30:43 pm
content: I need a two input, one output HDMI switch to connect two devices to a TV. I bought a random one which works with one device (a MacBook) but not with another one (a set-top box). I am a bit reluctant to buy another switch because I have no way to make sure it will work. It seems that none of these simple switches are truly passive, resulting in potential compatibility problems. Still it should be possible to just use high speed dumb multiplexers to implement a HDMI switch, no? (well except for the lines which need to carry some current but that should be easy to deal with). Anyone knows of an existing product that would be just that? Or maybe I was unlucky? All signals are 4K, nothing too fancy.Thanks!
Truncate or redither,  which is best for DAC?  - Page 1
Forum section: electronics / projects

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: September 06, 2025, 08:19:56 pm
content: I have an ASRC src4190 to supply 16bit DAC. The src can output 16,18,20 &24 bit output but adds dithering. I can use 16 out of 24bit to avoid redithering.Which solution is the best?

author: ArgyllGargoyle
author_rank: Contributor
timestamp: September 06, 2025, 10:35:09 pm
content: It probably adds the dither for the benefit of your DAC (eg to suppress idle tones in a sigma-delta dac). However, if you have a 16b nyquist dac, you may not require dither, and it may be slightly lower noise to simply truncate.

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: September 08, 2025, 04:54:39 am
content: Thank you for the advice, it greatly simplifies the interface.

author: Berni
author_rank: Super Contributor
timestamp: September 08, 2025, 05:29:58 am
content: It is a tradeoff between dynamic range and noise.By just truncating you can't get more than 16bits of dynamic range out of the DAC since very small signals just won't move the output or will move it in a very distorted square waveish way.With dithering you can get much more dynamic range out of the same DAC, allowing it to nicely reproduce signals smaller than its LSB step. But this comes at a price of adding noise somewhere. A good dithering algorithm will keep all the added noise in the high frequency end of the spectrum where the DACs antialiasing filters will remove it so you don't actually see any extra noise in the output. This works a lot better if the DAC has a higher sample rate than needed since that gives it a much larger span of spectrum between your highest frequency of interest and up to the DACs nyquist limit. Dithering essentially allows you to trade extra unneeded sample rate for more dynamic range. This is essentially how sigma delta converters work, but it can work with any DAC that is fast enough.

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: September 09, 2025, 05:37:35 am
content: The input data is already dithered at source. As the LSB is corrupt by noise, the extra bits bellow LSB I suppose enhances further the noise. If I adjust to output 16bits, the SRC will add again dithering but if I output 24 bit and truncate, I will add truncating noise instead of redithring.I understood that redithering is the least noisy.
Trying source micropower ic here in Australia - Page 1
Forum section: electronics / projects

author: donald
author_rank: Contributor
timestamp: January 20, 2013, 12:31:37 am
content: i have just recently designed micro-powered ATX power supply load Tester (0-50A) and really having bugger all trying find parts.. 1) AD589 and 2) OP90 or OP251...I am also Home dad that money doesn't grow on treees ... I Constantly scrounge around finding on street chuck out old stuff (TV,radio,etc), I do alot computer(s) Repairs and fix local electronic Stuff for low .. if any one can find me lead to any place here in Australia where i can order my Good's .it will much appreciated.
Trying to build 20V 500W PSU with server PSU - Page 1
Forum section: electronics / projects

author: gotofbi
author_rank: Contributor
timestamp: September 05, 2022, 11:55:45 pm
content: Hi,I am trying to build 20v 500W PSUI searched lot with converting server PSU into 12v or 24v chargers.I need 20V power supply so I can power multiple tiny computer.I can achieve this by using Chinese variable 480W (aliexpress.com/item/33014847184.html?gatewayAdapt=glo2kor)But, I am hoping to use trust worthy PSU rather than Chinese PSU if possible.I saw people built 24V PSU by merging 2x server PSU.Same technique, If I can find a model that can adjust voltage to 10v, I can merge 2x of them and it will be 20VHowever, most of server PSU starts from 600W and if I merge 2x of them, it becomes 1200W PSU which is way beyond my usage.So, Is there any power supply that I can perform OVP hack with supplementary hacks to make 20V PSU?Thanks!

author: moffy
author_rank: Super Contributor
timestamp: September 06, 2022, 12:16:45 am
content: Mean Well are a decent brand carried by Digikey, but you will pay a premium. They have a 600W/20V supply, of course no stock at Digikey:https://www.digikey.com.au/en/products/detail/mean-well-usa-inc/HEP-600-20/7703843Gives you a brand to search for.

author: moffy
author_rank: Super Contributor
timestamp: September 06, 2022, 01:17:59 am
content: The Mean Well 24V@500W has an adjustable voltage range of 20-26.4V but is limited to 21A max:https://www.meanwell-web.com/en-gb/ac-dc-single-output-enclosed-power-supply-output-rsp--500--24

author: Circlotron
author_rank: Super Contributor
timestamp: September 06, 2022, 01:41:38 am
content: If your server psu has 48VDC output I'd look for an extra psu that converts 48V to 24V.

author: gotofbi
author_rank: Contributor
timestamp: September 06, 2022, 04:41:28 am
content: I was hoping to modify something like HP HSTNS-PL18 750W Switching Power Supply

author: inse
author_rank: Super Contributor
timestamp: September 06, 2022, 05:45:08 am
content: There are a lot of modification instructions for server power supplies.They usually have a very limited adjustment range and to go above that, you have to trick the supervisory circuit.I destroyed two of them in the experimental phase.And those server supplies are LOUD as they are totally crammed and need forced cooling.

author: l7777
author_rank: Newbie
timestamp: September 11, 2022, 03:38:25 pm
content: Quote from: gotofbi on September 06, 2022, 04:41:28 amWhat you want can certainly be done with a DPS-600, not sure about the PL18. Theoretically it should be possible but no one has done it.

author: gotofbi
author_rank: Contributor
timestamp: September 16, 2022, 08:05:07 am
content: I saw this video as well but I couldn't understand the video language.Do you think its safe to try to boost 20v?I saw lots of example of modifying voltages between 9v to 15v on various models but non of them boosted to like 20vI also can modify it to 10v, and serial connection 2x of them to generate 20v but I really want to achieve this by just having one PSU
Trying to build a DIY IBM Pointstick like device - Page 1
Forum section: electronics / projects

author: PeterFW
author_rank: Frequent Contributor
timestamp: January 21, 2020, 05:07:18 pm
content: Hello!I would like to build a keyboard like device but instead of regular piano keys it should have a "IBM Pointstick" like device for each note instead of keys.There are a few pre-made solutions for this available, either magnetic or resistive.Due to the amount of keys needed, magnetic solutions are cost prohibitive.The only resistive input devices i could find are Gameboy touch sticks (the c button on DS devices) but whose are expensive too.From there i recalled the existence of Velostat and thought about designing my own sensors but the usual Velostat is a bit too thin and i have reservations about the longevity.I could swear i have seen a material like Velostat but the only other "conductive tape" i could find was Z tape which is not what i need.I thought about doing some experiments on my own with some silicone and carbon black but i would really love something i can just buy.Anyone got a suggestion?Greetings,Peter

author: george.b
author_rank: Frequent Contributor
timestamp: January 21, 2020, 05:11:46 pm
content: Why not use strain gauges, like the IBM/Lenovo TrackPoint does?

author: PeterFW
author_rank: Frequent Contributor
timestamp: January 21, 2020, 05:38:33 pm
content: Thanks for the reply!Did not think of that yet, after thinking a bit about it, i got problems figuring out a way how to make this work with strain gauges.Until now i thought the track points are resistive.Can you give me some links to so i can resarch it?I got a hard time finding the right key words.Greetings,Peter

author: george.b
author_rank: Frequent Contributor
timestamp: January 21, 2020, 05:50:25 pm
content: Well, depends on what you call "resistive". Strain gauges are resistive, in that they change their resistance according to deformation.Perhaps the original patent for the TrackPoint could help:https://patents.google.com/patent/US5867808A/en

author: PeterFW
author_rank: Frequent Contributor
timestamp: January 21, 2020, 07:31:55 pm
content: Thanks, did not get me closer yet but send me down a rabbit hole of other research and ideas.
Trying to build an earth leakage device that will alarm at 30V+ - Page 1
Forum section: electronics / projects

author: challie2
author_rank: Contributor
timestamp: January 16, 2025, 04:02:07 pm
content: Hi allas mentioned in the subject what im trying to build, is an electronics device that detects earth faults. Essentially trying to make my own contactless tester. And also the ability to attach a test lead with a crocodile clip, to detect earth faults, essentially a 2 in 1 job. When everything is normal and no earth fault detected, there is a 2 contact relay with 1 NC and 1 NO. When the coil of the relay is energised an LED is illuminated. When a 30V+ fault is detected, it de energises the relay the 1st LED extinguishes, and then another LED with a Buzzer are powered. There should also be a test button to test the circuit works, and a reset button, if the fault is still there after the reset button is pressed, it instantly alarms again. Attached is an image of what I have made so far. I am really struggling to get it working, and could really do with some help I am beginner with Electronics.Thanks

author: moffy
author_rank: Super Contributor
timestamp: January 16, 2025, 09:49:15 pm
content: So are you trying to build basically an insulation tester for earths?

author: wasedadoc
author_rank: Super Contributor
timestamp: January 16, 2025, 10:06:10 pm
content: Earth leakage testers usually monitor current, not voltage.

author: David Hess
author_rank: Super Contributor
timestamp: January 16, 2025, 11:40:42 pm
content: Check out the service manual for the Tektronix A6901 Ground Isolation Monitor which does what you are describing. It has full schematics.https://w140.com/tekwiki/wiki/A6901

author: challie2
author_rank: Contributor
timestamp: January 18, 2025, 02:47:36 am
content: I suppose of sorts yes. Thanks for the reply

author: challie2
author_rank: Contributor
timestamp: January 18, 2025, 02:48:37 am
content: Kind of what I’m trying to build. Thanks

author: Terry Bites
author_rank: Super Contributor
timestamp: January 18, 2025, 03:50:42 pm
content: What you actually want to detect is still very unclear. It doesn't seem like you want to measure earth leakage currents.I think its an earthing failure detector. So, say when loss of ground at the low side of your circuit casues it to climbs to 30V.When circuit ground gets 30V higher than PE maybe?In which case a latching voltage detector is what you need and it appears your schematic is intended to do just that.Here's an idea for a cheap detector made from the bits you might already have laying about the bench.
Trying to build my own RaspBerry clone - Page 1
Forum section: electronics / projects

author: sidereal
author_rank: Contributor
timestamp: September 18, 2021, 12:32:45 pm
content: HiI am starting my hand on building my own Raspberry Clone. I have built Arduino clones, before Arduino was a thing, and you had to use DIP package ATMEL controllers.Now I want to try my hand at ARM based CPUs in contrast to MCUs such as the typical ATMEL products (e.g. ATMEGA xxxx).This is my first time with ARM, so please bear with me.I have chosen the Sitara family of processors, AM437x series. I am using the open source BeagleBoan project as my start point.I as seeing in the Datasheet for AM 335x (the one used by BeagleBones) as well as for AM 437x, that the decoupling capacitor can be 10.08 µF . Seehere, page 93.But theBeagleBone schematicuses > 20.13 µF capacitor. See page 5. How is the correct value of the capacitor determined?Thank you.

author: Terry Bites
author_rank: Super Contributor
timestamp: September 18, 2021, 12:47:18 pm
content: Cash to burn??

author: thinkfat
author_rank: Unknown
timestamp: September 18, 2021, 12:51:40 pm
content: Read the datasheet more thoroughly. Don't omit the footnotes. Good luck.

author: tmadness
author_rank: Regular Contributor
timestamp: September 18, 2021, 09:53:34 pm
content: So a few things:I admire your moxie and wish you the best of luck. But you should probably clarify to your self what you are doing, I don't see a clear goal and there's a bit of confusion in your post.Second, decoupling is a interesting topic, there are objective Measures of effective implementation. But few projects require that kind of analysis. Rules of thumb:spread your decoupling into two types bulk and local decoupling. Bulk decoupling is what you are probably asking about, the large 10/20 uf cap. Size/price matters if you are going to manufacture at volume, hence why the beaglebone has 10 uF caps. Err on the side of larger caps when you are doing something where pennies extra don't matter. The other kind of decoupling, local decoupling, take from the reference design, I think I saw 10nf and .1 uf caps on the beaglebone. Get these as close to your pins as possible. Don't skimp on local decoupling, 1 per pin or 1 per group of 2-4 pins minimum.Arguably, placement and layout of decoupling matters more in most cases than absolute value. Place the caps close to the pins. Always. Keep a high quality ground and power pour accessable to your caps. Bad designs have meandering power rails and ground loops. If you can afford it put a power and gnd plane underneath. If you can't then wide traces, that are the closest to a straight line from your power supply. Go for the widest via that your design can fit, ideally every pin gets its own via or direct power connection. At the power supply side go for multiple parallel vias, like go Overkill.And finally, choose quality ceramic caps. Don't use electrolytic, tantalums only for bulk, ideally bulk should be ceramic as well.

author: sidereal
author_rank: Contributor
timestamp: September 21, 2021, 09:38:15 am
content: Thanks guys
Trying to decode Daktronics scoreboard data - Page 1
Forum section: electronics / projects

author: n1ist
author_rank: Contributor
timestamp: November 14, 2017, 04:05:06 am
content: I am trying to decode the data that goes between a Daktronics All-Sport 5000 controller and scoreboard at an ice rink (my goal is to drive the scoreboard without the controller). Based on what I could find, this is a current-loop feed at 19200 baud. I have used a B&B current-loop to rs232 converter to download the data to my PC, and based on the embedded ASCII string "46015000236" where 4601 is the game code for hockey, 5000 is the model of the controller, and I believe 236 is the firmware version, I am getting valid data.I am seeing that each packet begins with 0x55 0xAA then 4 bytes, then 0x22, and a variable amount of data following. Looks like the last byte is a checksum (all lines sum to 0x01 mod 0xFF).This is a sample of the data (with the leading 55 AA removed from each line):QuoteDoes anyone have any idea about this data format? It isn't their enhanced RTD format; that's a readable ASCII data. More likely, it is 7-segment data. The controller constantly sends out the data; when you plug in the scoreboard, it will start displaying shortly (probably syncing on the line with the game and model number).Thanks./mike[Edited when I fixed a bug in my interpreter program - all lines have 4 bytes between 0x55 0xAA and 0x22 with a checksum of 0x01]

author: n1ist
author_rank: Contributor
timestamp: November 25, 2017, 03:11:18 am
content: I called Daktronics; they claim they don't have any documentation on this data format. One more byte figured out - the second byte after the 55 AA is the length of the variable section (between the 22 and checksum)/mike

author: phil from seattle
author_rank: Super Contributor
timestamp: November 26, 2017, 08:12:09 am
content: Can you record a session and then play it back to the scoreboard? If so, you could take your time making changes to see what happens.

author: abraxa
author_rank: Frequent Contributor
timestamp: November 26, 2017, 11:41:19 am
content: Alternatively, you could make a change using the original software and see how the data changes, too.
Trying to determine EPROM access speed - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: December 05, 2022, 12:03:59 pm
content: I have these Chinese EPROMs that are rebranded and second hand. e.g. some are not completely erased, and when you rub off the new paint it has Chinese writing on the ceramic body. Despite this, I have been using them for quite a while and generally they are okay for my purpose. They are (falsely) labelled as ST and 100nS access time. Actual access time is somewhere between 1.25 and 2.5 uS. If I try and read it 1.25 uS after addressing it doesn't work but after 2.5uS it does.Decided to rig up something to try and measure the actual access time. I simply toggled A0 address line and compared that edge with one of the data lines that happened to change state. Lo and behold, the data changed20nSafter the address! No EPROM is that fast, especially these ones. What is a good way to measure the access time?

author: srb1954
author_rank: Super Contributor
timestamp: December 05, 2022, 12:27:02 pm
content: Quote from: Circlotron on December 05, 2022, 12:03:59 pmWhat is your set-up for measuring the access time at between 1.25us and 2.5us?I don't think EPROMs were as slow as that since at least the mid 1970s.

author: Terry Bites
author_rank: Super Contributor
timestamp: December 05, 2022, 12:31:08 pm
content: check "AC MEASUREMENT CONDITIONS" in a trustworthy datsheet

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 05, 2022, 12:35:58 pm
content: Another vague question: Unknown eeprom model (Because there's only one eeprom model in the market, right?), no details at all...Anyways 100ns spec is worst-case scenario, temperature, voltage, whatever conditions, will affect it.Also you might get 20ns in *some* data pins, but maybe not all of them will be fully settled down.

author: Circlotron
author_rank: Super Contributor
timestamp: December 05, 2022, 12:38:20 pm
content: Quote from: srb1954 on December 05, 2022, 12:27:02 pmSet the address then 5 cycles later (5 x 250nS) read the data. No good.10 cycles later reads okay.

author: Circlotron
author_rank: Super Contributor
timestamp: December 05, 2022, 12:42:04 pm
content: Quote from: DavidAlfa on December 05, 2022, 12:35:58 pmEPROM, not EEPROM.That's right, no data. It's some oddball rebadged Chinese fake rebadged as ST. M27C801. 1M x 8.

author: amyk
author_rank: Super Contributor
timestamp: December 05, 2022, 02:35:14 pm
content: Since it has an exposed die, you could look for markings on it to determine what it really is.
Trying to figure out a motor control circuit which has a Triac. - Page 1
Forum section: electronics / projects

author: Yamin
author_rank: Frequent Contributor
timestamp: April 20, 2019, 05:43:00 pm
content: Hi, I'm tracing a motor control circuit of a coffee grinder. Nothing is broken just doing it for educational purposes. I do not understand how the following resistors and capacitor is connected and its purpose, it doesn't look right to me as I have not seen it like this before. I am assuming its the snubber circuit.Where is the neutral connection coming into? :S. I haven't continued tracing the rest of the circuit yet. I'm stuck at this point trying to figure out whats happening here. Maybe I'm drawing it in a way that is confusing...The motor is an asynchronous motor.Thanks in advance for the help

author: Yamin
author_rank: Frequent Contributor
timestamp: April 20, 2019, 06:14:59 pm
content: I have drawn the other part of the circuit (not the gate connection though) and I'm afraid its even confusing more

author: soldar
author_rank: Super Contributor
timestamp: April 21, 2019, 08:21:22 am
content: It has a speed control knob? My guess is that it is a triac phase control and the transformer supplies low voltage to some kind of control circuit.

author: mikerj
author_rank: Super Contributor
timestamp: April 21, 2019, 09:24:18 am
content: I suspect the main problem is that you've drawn it in a particularly confusing way. The X2 cap and 39k resistor are connected right across the triac in a classic snubber configuration, but that isn't immediately obvious from the diagram as drawn. The 180k is a bleeder resistor to ensure no charge remains on the snubber after power has been removed.

author: soldar
author_rank: Super Contributor
timestamp: April 21, 2019, 09:54:01 am
content: Have a look at this thread and you can reverse engineer the circuit.https://www.eevblog.com/forum/beginners/pcb-to-scheme/

author: Yamin
author_rank: Frequent Contributor
timestamp: April 27, 2019, 08:14:30 am
content: Thanks everyone for the response guys. I came across this explanation about Triacs athttps://www.nutsvolts.com/magazine/article/triac_principles_and_circuits_part_1It has got some similarities for the circuit I have drawn. Could this be it?
Trying to figure out a photomultiplier board. What is TP1321? - Page 1
Forum section: electronics / projects

author: Artlav
author_rank: Frequent Contributor
timestamp: July 27, 2018, 07:07:16 am
content: I got a late 70s photomultiplier with a driver board on it, and i'm trying to make sense of it.The central piece of the board is an 8-pin can part with TP 1321 marking on it, and "Malaysia-F" on the side:I have not been able to google anything about it.Anyone have an idea what it could be?Omitting the resistor stack, the schematic is like so.I've triple-checked, and there really is no connection to the ground on it.The part takes input voltage, the output of a voltage divider from that, and the PMT's output, and gives out two wires of what i presume is output.

author: daqq
author_rank: Super Contributor
timestamp: July 27, 2018, 07:16:32 am
content: Could be a Teledyne relay according to google/octopart. They made relays in that kind of package.https://octopart.com/tp1321-teledyne+relays-4027641

author: helius
author_rank: Super Contributor
timestamp: July 27, 2018, 07:18:24 am
content: Philbrick Teledyne Wideband, High Zin, High Slew Rate Operational Amplifierhttp://www.philbrickarchive.org/1971%20optimized%20microcircits.pdf

author: Artlav
author_rank: Frequent Contributor
timestamp: July 27, 2018, 08:24:48 am
content: Yep, that looks like it.Here i found a pdf with details like pinout in it -https://www.osti.gov/biblio/6057583Thanks!
Trying to figure out audio mixer input section/preamp - Page 1
Forum section: electronics / projects

author: Yamin
author_rank: Frequent Contributor
timestamp: January 14, 2024, 07:25:54 pm
content: Hi guys,I'm going through this schematic of a soundcraft EFX8 mixer. I was hoping that you could breakdown the function of the transistors and how the gain is controlled via 10Kohm pot. This is a common circuit I see with other mixers too. Also could you direct me to some resources which explain these kind of preamp circuitry.Thanks in advance.

author: magic
author_rank: Super Contributor
timestamp: January 14, 2024, 08:59:02 pm
content: It's a differential pair of open loop common emitter amplifiers.Each PNP/NPN combo is a Sziklai pair, acting like an "ideal" PNP (high β and very constant Vbe).The bases are biased to ground by resistors and modulated with input signals.The emitters simply follow the bases and differential input signal appears across the gain pot.AC current equaling differential input voltage divided by pot resistance flows through the pot and C500.The pullups to +V2 provide emitter bias, but gain pot current subtracts from one of them and adds to another.The two different currents pass through the Sziklai pairs to their 1.2K collector loads wired to -V1.Differential voltage appears at the resistors.Gain is 1.2K over gain pot resistance, maybe ±6dB. Do the math, I'm lazy.
Trying to figure out how a stormcope/strikefinder lightning detector works - Page 1
Forum section: electronics / projects

author: 4flyer
author_rank: Contributor
timestamp: April 20, 2020, 02:28:04 am
content: Hey guys,I am trying to figure out how stormscope/strikefinder lightning detectors work. These are lightning detectors that are put on aircraft that not only indicatewhenlightning is nearby, it displays the relativedistance and directionof the lightning. I get that the system detects the radio waves emitted by the lighting (probably on 500kHz), and then sends the signal to a processor to figure out the strength. The antenna also seems to be a loop antenna but how they make the antenna so small and how they get it to "rotate" electrically is beyond me. Can anybody help me or point me in the right direction on how these systems work? I would love to try and make my own. Thanks! Here are some links to what I am referring to:https://www.bennettavionics.com/wx-500-stormscope/http://www.insightavionics.com/pdf%20files/STRIKE%20GUIDE.pdf

author: cur8xgo
author_rank: Regular Contributor
timestamp: April 25, 2020, 04:48:24 am
content: https://patents.google.com/patent/US5295072A/enshould be able to start there and find all the other patents as wellwould def be a fun projectEDIT: actually here you go, I think this is where it started..at least in the 90'shttps://patents.google.com/patent/US4023408A/enI bet you a lightning scope/meter like this evolved over 50 years and there is probably some kind of earlier version in the 70s, 60s, 50s, etc..EDIT: OH dam that thing is from the 70s! And there is a schematic! I do not need more projects but this is pretty great
Trying to figure out what component is shown in this diagram. - Page 1
Forum section: electronics / projects

author: Ben321
author_rank: Frequent Contributor
timestamp: January 06, 2018, 06:07:58 am
content: I was looking at this diagram of how a simple tapped inductor (in effect an autotransformer) is combined with an ignitor for starting and and maintaining current through an arc lamp. It seems like a pretty simple circuit, but the ignitor contains one component I don't recognize the schematic symbol for. In the below diagram you will see symbols in the ignitor part of the circuit for capacitor, resistor, and diodes. But then there's this one component who's symbol looks like the letter Z. I have no idea what component this is. If anybody here knows, please post a reply to this thread.

author: Ben321
author_rank: Frequent Contributor
timestamp: January 06, 2018, 09:44:19 pm
content: Quote from: blueskull on January 06, 2018, 06:21:39 amSo the component with the Z shaped symbol is some kind of spark gap?I wonder how that overall starter circuit works?

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: January 06, 2018, 10:02:27 pm
content: Quote from: Ben321 on January 06, 2018, 09:44:19 pmI am quute sure that is a starterBasically if its a starter, made up of two vertical wire with a small gap and a capacitor in parallel, the voltage create an arc between this plates and bend them, closing the circuit and then the metal cool down and the metal return in the original position, re'creating the arc and so onSorry If I am wrong
Trying to figure out what this three pin connector is, not XLR, proprietary? - Page 1
Forum section: electronics / projects

author: guy232
author_rank: Contributor
timestamp: June 04, 2020, 09:42:36 pm
content: tl;dr: Trying to figure out what this connector is. It's a bit bigger spacing than XLR. Only 2 of the pins are wired, the third pin is a dummy. I don't have it on my bench yet but I was told the measurements were " Pin dia 2.90 mm, motor pos to neg pins center to center 11.20 mm, the other dim 7.25 mm" I also created a collage of different angles of this connector in hopes it may help ID it. Perhaps it is proprietary or?Pics attached below, hi-res versions hosted here:https://imgur.com/a/CC0M11FFull post:I'm wanting to power a blower motor with a usb power bank instead of the original 4.9-5v 2A NiCd batt that it was designed to use. I was hoping to avoid altering the blower motor and instead use an adapter to convert the blower's connector to a USB2.0 male so I could insert it into a power bank.I don't have the blower in my hands yet, was hoping to have all the parts ready and waiting for it when it arrives but I hit a snag. Does anyone happen to know if this type of connector has a name? I thought it was XLR at first but then was told by the person giving the blower to me that the dimensions on the pins were " Pin dia 2.90 mm, motor pos to neg pins center to center 11.20 mm, the other dim 7.25 mm." which sounds a bit bigger than an XLR. Any clue if this may just be proprietary or am I overlooking an obscure connector?
(SOLVED) Trying to find a matching DIN Connector for the one on this board.. - Page 1
Forum section: electronics / projects

author: simmiv
author_rank: Contributor
timestamp: February 09, 2021, 12:17:03 pm
content: I've got an old IBM PC JX from 1985. It has three expansion connectors on the motherboard.The one I'm interested in is for 128K Ram expansion.. It looks like a DIN 41612 connector with two rows of 32 pin holes with a pin spacing of 2.54mm with 64 pins in total. I can find similar matching males with right angle pins, but not with the four key's as shown on the female version. The EXRAM128 is the one further away. The near one is the same, except it has two rows of 16 pins with 32 pins in total and the same pin spacing. Here is a photo of the connectors on the board.You can see four key's or recesses on the side of the connector.. I can't find any other ones with the same pattern. I'm not familiar with these DIN connectors, so not sure if this is custom or not.. The female does have these keys as well as shown here from one of the 128Kb ram expansion board that plugs into the one on the motherboard.. Perhaps they really don't matter as they are both recessed on the male and female. i.e. the ones inside the mail connector are also recessed. Does it matter then if the replacement male doesn't have these recessed sides?Does anyone know if these connectors would be stock or customer. I was thinking about creating my own memory expansion card as these are not available anywhere as this PC is so rare. It was sold in Japan, Australia and NZ. Not anywhere else. I think less than 20,000 of them was sold across all countries i.e another IBM PCjr flop for IBM.. IBM made 256Kb and 384Kb expansion boards after the initial launch in Japan, so they are even rarer..If you really want to learn more about this IBM PC JX Flop I have done a video on it. See herehttps://www.youtube.com/channel/UC8JeS2mdR76rNjvzPFCnqbwSimmi

author: penfold
author_rank: Frequent Contributor
timestamp: February 09, 2021, 01:58:04 pm
content: No photo shows up for me...Ernihttps://www.erni.comis usually the go-to manufacturer for 41612 connectors so chances are if its not custom it'll be listed somehow in their 41612 range and then finding it in a distributor will be challenge number 2

author: strawberry
author_rank: Super Contributor
timestamp: February 09, 2021, 03:21:13 pm
content: https://eu.mouser.com/Connectors/Backplane-Connectors/DIN-41612-Connectors/by datasheet Hirose Connector make them with keyhttps://eu.mouser.com/datasheet/2/185/PCN10_CL0583_0077_3_72_2d-1619209.pdf

author: simmiv
author_rank: Contributor
timestamp: February 10, 2021, 09:06:40 am
content: Thanks,I see the ones on the boards are Hirosi brand and I've now ordered a few new ones. For the 128Ram expansion i.e. J4 the Hirosi p/n is PCN10-64P-2.54DS(72).. You can find it on some of the suppliers i.e. Mouser, Digikey etc..Rgds,Simmi
Trying to Find a Rad Hard I2C Buffer - does one exist? - Page 1
Forum section: electronics / projects

author: matthej
author_rank: Newbie
timestamp: June 03, 2022, 03:35:06 pm
content: Hi,I need to design a rad hard (space grade) I2C buffer for my I2C interface. There are many commercial versions out there but can't find a rad hard (space grade) one.Does anyone have any experience with this? Does one exist?Can I make my own?Thanks!Matty

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: June 03, 2022, 06:28:41 pm
content: Did you try Avago, Cobham (caes.com), Teledyne e2v, Lansdale, whiteedc, Holt, Aeroflex, Omnirel, ?There must be a solution,as it is flown already (Cubesats and other).In how far does it even need a special driver other than one fitting the logic level?Maybe look at the interface ICs and Buffers for which a SMD exists (via DLA)or try here:https://nepp.nasa.gov/pages/npsl/mic/hyb/Nsl_sumh.cfm
Trying to find an enclosure - Page 1
Forum section: electronics / projects

author: akis
author_rank: Frequent Contributor
timestamp: June 26, 2016, 08:52:36 am
content: The dimensions I need are no less than :internal height 48mm, internal width 150mm, internal depth 175mmpanel at the "front" 150mm x 50mm (or thereabouts)I currently use Hammond made of ABS 1598CGY but it is slightly too small and cannot fit the batteries inside.Thanks

author: IconicPCB
author_rank: Super Contributor
timestamp: June 26, 2016, 11:30:32 am
content: How many dozen do you need?

author: ZeTeX
author_rank: Frequent Contributor
timestamp: June 26, 2016, 01:34:27 pm
content: Quote from: akis on June 26, 2016, 08:52:36 amLook in aliexpress \ eBay if you need only one, or your local distributors.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 26, 2016, 02:34:22 pm
content: http://www.budind.com/view/Plastic+Boxes/Plasticase+Style+D
trying to find IC supplier for MC10116 - Page 1
Forum section: electronics / projects

author: Chopsticks
author_rank: Regular Contributor
timestamp: January 20, 2014, 08:18:28 am
content: hi I'm trying to locate a place to buy this IC in Australia, so far i can only find it available from Futurlec and ebay. futurlec always takes like 6-8 weeks for stuff to arrive and ebay prices start at roughly $10. i guess if i have to then ebay will do but is there anywhere else to look?thanks guys

author: Chopsticks
author_rank: Regular Contributor
timestamp: January 20, 2014, 01:18:06 pm
content: thanks a million mate