hybridfree/eevblog-posts huggingface dataset:
current waveform in transformers   - Page 1
Forum section: electronics / beginners

author: hussamaldean
author_rank: Unknown
timestamp: April 12, 2018, 06:54:47 am
content: Hi allI striped an length of wire and I used as current shunt resistance sensor to measure the current using my oscilloscope and here is the resultsthe oscilloscope let me see things like never beforewhat interesting was, the shape of the current which doesn't look like the input voltage (blue is the voltage while yellow is the current)it turns out the core of transformer has nonlinear magnetising core which leads to this phenomenonthings you learn from shunt and oscilloscopeNote: I didn't use any differential probe

author: Zero999
author_rank: Super Contributor
timestamp: April 12, 2018, 09:27:01 am
content: What was the load on the transformer?Transformers can cause distortion to the current, due to hysteresis in the core, but that normally happens when they're heavily loaded. Another more common form of distortion is not from the transformer itself, but the load, which is often a bridge rectifier with a smoothing capacitor, which draws current, when the secondary voltage is at its peak and none during zero crossing.

author: hussamaldean
author_rank: Unknown
timestamp: April 12, 2018, 09:31:40 am
content: Quote from: Hero999 on April 12, 2018, 09:27:01 amopen circuit test

author: capt bullshot
author_rank: Super Contributor
timestamp: April 12, 2018, 09:45:11 am
content: In case the transformer was unloaded, this is the normal magnetising current superimposed to the "ideal" inductive behaviour of an unloaded transformer (which would just be a 90 degrees lagging current waveform).The peaks result from the usual "optimization" done on a "normal power transformer", say the core is running near to it's saturation limit. If you lower the voltage, the current waveform would become more sinusoidal.

author: Benta
author_rank: Super Contributor
timestamp: April 12, 2018, 01:06:12 pm
content: Yeah, the magnetizing current is nonlinear due to the iron hysteresis and the magnetizing curve. It's of low magnitude, though. If you start resistively loading the transformer, you'll see the input current becoming more and more sinusoidal as the current increases, as what you'll see is the reflected load current with the magentizing current superimposed.You'll also see the current becoming more and more ohmic. The magnetizing current is shifted 90 degrees (can be nicely seen on your scope), but the load current is resistive, so the phase shift will move towards 0 degrees.

author: schmitt trigger
author_rank: Super Contributor
timestamp: April 12, 2018, 01:41:38 pm
content: Quote from: hussamaldean on April 12, 2018, 06:54:47 amYou got that right. That is why I advocate to any person who is serious about electronics as a hobby or as a profession, to invest on a scope.How many times have you seen posts like "my switchmode supply keeps burning Mosfets, help!". And when someone asks to see the waveforms, they reply: "I don't have a scope"
µCurrent with LCD frontend - Page 1
Forum section: electronics / beginners

author: geartech
author_rank: Newbie
timestamp: September 13, 2021, 09:57:26 am
content: Hello,I was wondering if it would be possible to simply hook up a microcontroller via ADC to the output of the µCurrent gold and display the readings on a little LCD. Or would there be any technical issue with that?Any thoughts on this?ThanksKind regards

author: Kleinstein
author_rank: Super Contributor
timestamp: September 13, 2021, 10:36:53 am
content: It should work that way.The µC internal ADC may not be very high resolution (e.g. 10 bit) and the range is usually some 2.5 - 5 V. So one may wand a little more amplification and the 1:1000 steps in the shunts are a bit large for a 10 or 12 Bit ADC. So at the lower end of the range the resolution would be poor. Unless the µC has a really good ADC inside, I would consider an external ADC like MCP3421.

author: geartech
author_rank: Newbie
timestamp: September 14, 2021, 01:35:47 pm
content: Ok, thanks for the reply.

author: comfortcube
author_rank: Contributor
timestamp: September 14, 2021, 02:52:41 pm
content: I'm sure for just a quick display of values, that should be fine. Without deeper consideration, this approach will likely not display the same level of accuracy/precision/resolution as measuring the output of the uCurrent with a good multimeter. You can get in more detail and account for accuracy/precision/resolution requirements, of course - will just be a bit more work.
Curve tracer / Rail splitter sourced current / Horizontal adjustment  - Page 1
Forum section: electronics / beginners

author: Zielsziek
author_rank: Contributor
timestamp: April 17, 2025, 05:17:46 am
content: Hello,I have built and been playing with this curve tracer. So far so good, I am enjoying it. I have three questions about it.1. I find that I cannot adjust the trace to be horizontal when input is open. I suspect that this is because of the values for the adjustment section R21 and RV2 and RV3. I changed R21 from 100K to 50K, but the improvement was mediocre.2. When I short the leads I am expecting a vertical trace, which I am obtaining, but that trace is roughly 1.25 divisions long. This, I believe to be because of the rail splitter which cannot supply enough current. Should I switch to a rail splitter with two transistors? Or maybe a different op-amp. I know that normally a center tapped transformer would be used here, but I wanted to avoid AC. I have had issues before here, where C3 and C4 were causing oscillations of the split supply and I removed them.3. Was it a bad ideea to switch mechanically between the frequencies? I find that if I touch the switch, which is metal, my oscillator starts behaving somewhat erratically. Should I have used something like a HEF4051B mux/demux ic?Thank you.
Custom Arduino PCB - not working after assembly?  - Page 1
Forum section: electronics / beginners

author: CodeBreaker
author_rank: Newbie
timestamp: April 22, 2018, 06:58:46 pm
content: Hi guys!I'm having a big issue with my design. Here's what happened.I have made a custom Arduino PCB (Schematic and gerber files attached). I ordered Blank PCB and soldered it myself and it worked great. I rearranged the PCB and send it to production to be assembled. After receiving them I went on and programmed them. After successfully burning program using Arduino as ISP I went and checked the serial port and to my surprise, nothing was written there. So i burned a simple blink program and instead of blinking the output pin, the pin was always at 5V. So all the pins I set topinMode(LED, OUTPUT);are always on HIGH regardless if the program sets it to HIGH or LOW. I don't understand the problem. I can burn the program to the ATmega328P with no problems but when using the outputs I always get 5V. The test PCB with the same components is working perfectly. I only rearranged the components and let the autorouter do its thing (No errors). I've checked continuity on all pins and they are correctly wired. I can also burn the bootloader and flash it with Arduino IDE as a regular Arduino. So, what gives?Did i mess anything up with the rearranging of the components? is it possible that something happened in the assembly stage or transport?I hope I don't have to toss $2000 in the trash...

author: Sparker
author_rank: Regular Contributor
timestamp: April 22, 2018, 07:10:18 pm
content: I don't know how they handle fuse bits in Arduino, but maybe you have to set them up properly on a new MCU. Some devices might have a watchdog timer running by default.

author: Yansi
author_rank: Super Contributor
timestamp: April 22, 2018, 07:17:24 pm
content: Is there any manufacturer's bootloader in that AVR, or does the arduino use a custom bootloader?The voltage regulator has the input cap where?!

author: CodeBreaker
author_rank: Newbie
timestamp: April 22, 2018, 07:31:34 pm
content: I love you man! And I'm an idiot. Thank you very much.On the test board I burned Arduino bootloader first which set the fuse bits and on the new one I burned the program without setting the bits.

author: Sparker
author_rank: Regular Contributor
timestamp: April 22, 2018, 07:54:02 pm
content: Cool! Once I also wasted some time because I forgot about the fuse bits... now it's fused in my brain to always check them.
custom dimmer linear AC power - Page 1
Forum section: electronics / beginners

author: spetroce
author_rank: Newbie
timestamp: July 09, 2019, 04:29:47 am
content: I am working on a dimmer circuit for a light bulb. I've implemented an analog circuit that detects the zero crossing on the AC mains and sends out a trigger pulse to the MCU on our product to handle the forward phase switching of the dimmer. This all works fine. Something I noticed though, was the brightness to the light does not increase linearly with the duty cycle of the dimming. I then realized that taking equally sized discrete steps along the sine wave does not always translate to the same area under the sine wave. That is, we should be taking discrete switching steps along the sine wave in our dimming such that area under the curve for each step is the same. So I wrote some code that takes the discrete integral of the sine wave, blah blah, and now I have steps that each have the same area under the curve. Great. I don't know if this is correct though. My theory may be off. Does this mean that thepowerwill increase linearly? In other words, with a purely resistive load, is the the voltage/time area equal to the power (or is it energy) that the load will experience? My thought on this whole thing was with PWM on a normal DC source where the increase in duty cycle is a linear increase in the area under the square wave form. So I just wanted to mimic the same thing with the AC sine wave, but with the AC we have a varying voltage and therefore the current is varying along the sine wave... This is where my theory weakens. I'd greatly appreciate any input on this. Thank you!This chart below shows the discrete steps. The area between any two points is the same.
Custom heatsink mounting - Page 1
Forum section: electronics / beginners

author: Peacefrog
author_rank: Contributor
timestamp: January 07, 2020, 03:56:31 pm
content: I've mounted transistors to heatsinks before and used off the shelf kits (both for the heatsinks themselves and insulation), but I'm now creating a custom solution for a project, based on a single piece of aluminum that I'm cutting and drilling (and need to mount four transistors to).This got me thinking: the plastic insulator I'm using (alongside the mica pad, to ensure the bolt and the transistor don't short) isn't as deep as the aluminum. The bolt should therefore still be insulated, but there will be some part that *isn't* shielded by the plastic internally, with an air-gap between it and the metal.This is probably 'normal', based on some Googling, but should I be looking for a deeper plastic insulator instead that lies flush either side?

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 07, 2020, 04:15:35 pm
content: By "plastic insulator" you mean the flanged nylon washer that inserts between the transistor's mounting hole and the screw?

author: Peacefrog
author_rank: Contributor
timestamp: January 07, 2020, 04:20:01 pm
content: Yup - sorry, I guess the correct term is shoulder washer.

author: andy3055
author_rank: Super Contributor
timestamp: January 07, 2020, 05:54:21 pm
content: I don't see any issue with that unless you have high voltages that could arc over from the screw stem to the heat sink.

author: fourtytwo42
author_rank: Super Contributor
timestamp: January 07, 2020, 06:14:49 pm
content: Quote from: Peacefrog on January 07, 2020, 03:56:31 pmThis makes me think your using the shoulder insulator in the wrong place maybe, every time I use them they are in the TO220 or whatever device flange so the screw is at heatsink potential NOT power device tab potential. I think this explains why you think they are to shortOf course high voltage is a whole other ballpark!

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 07, 2020, 10:33:38 pm
content: What fortytwo said.The shoulder washer's flange is only as long as the transistor's mounting tab is thick.

author: Peacefrog
author_rank: Contributor
timestamp: January 08, 2020, 01:59:50 am
content: That makes sense, now - thanks all!
Custom made JST cable - Page 1
Forum section: electronics / beginners

author: chancs
author_rank: Contributor
timestamp: March 12, 2020, 02:13:26 pm
content: I would like to custom made some cables using JST connectors (VH, XH, and SH). Which is the correct tool to crimp the terminal?I am looking at the crimper made by ENGINEER INC, I think they are made in JP, which should be good quality.Will this one cover all my needs? -->https://rhinotools.com.au/product/pa-09-micro-terminal-crimper/Or do I need to get the full set -->https://rhinotools.com.au/product/engineer-pad-02-crimping-kit/, will this set cover all my needs?Or do you have any better recommendations in the similar price range?Thanks,Sam

author: tooki
author_rank: Super Contributor
timestamp: March 12, 2020, 04:11:51 pm
content: I highly suggest reading this in-depth survey of the crimping world:http://tech.mattmillman.com/info/crimpconnectors/

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 12, 2020, 04:54:36 pm
content: I use this one by engineer (The PAD-12 model), it works great for XH connectors and a few others that I can't remember the names of that I've used on it too.http://www.engineer.jp/en/products/pad11_13e.html
Custom modular power supply - Page 1
Forum section: electronics / beginners

author: molmagman
author_rank: Newbie
timestamp: May 01, 2020, 05:50:19 pm
content: Hi - new to the forum, new to electronics in general so be gentleI started collecting vintage home computers last year and I'm getting nervous about power supplies. Lots of them have multi voltage power supplies including mixtures of AC and DC low voltage.I want to make modular supplies for them with a customisable rail for power (1 - 5 modulates in a housing) and plug in a module which takes 240V input but can be configured to output DC 3 - 24V *or* AC 3 - 24V or something like that.Is this possible?

author: wizard69
author_rank: Super Contributor
timestamp: May 02, 2020, 08:07:37 pm
content: If I understand your question, I would have to say yes. Here I'm thinking a rack that takes plug in power supply modules that output the various voltages you need. Now I would NOT suggest this for a beginner as this would involve switch mode power supply design in most cases. On the flip side I'd seriously consider spending some time looking for a power supply(s) that delivers most of the functionality you want.Quote from: molmagman on May 01, 2020, 05:50:19 pm

author: Doctorandus_P
author_rank: Super Contributor
timestamp: May 03, 2020, 01:33:53 pm
content: Start by designing and building some simple power supplies, and then, when your knowledge grows, make more elaborate versions.Then later, you can combine multiple simple design in a multi rail combination.Just start simple.

author: Vovk_Z
author_rank: Super Contributor
timestamp: May 04, 2020, 11:54:22 pm
content: Quote from: molmagman on May 01, 2020, 05:50:19 pmLook for "MINI-ITX ATX DC-DC Power Supply Convertor".For example.They cost usually less than that. May be it can help. There is one drawback - they don't have -5V channel.
Custom optimize settings in a code, Keil 5 - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: July 03, 2018, 02:43:08 pm
content: 1. I am using uVision 5, C51 V9.52 & wrote a code. It has multiple source files, one of which is task_manager.c.In it it has three functions:a) bit_reset()b) bit_set()c) rgb_write()2. These are very time critical need to optimize for full speed, three functions only, rest code I want to be optimzie for size to save overall space.Whats the way to do that?3. These settings I do for speed in keil,a)Use Extended Linker LX51 instead of Bl51b) Level 8: Reuse Common codec) Speed emphasisd) Linker code pakcing(), AJMP4. These settings I do for size in keil,a)Use Extended Linker LX51 instaed of Bl51b) Level 11: Reuse Common codec) Size emphasisd) Linker code pakcing(), AJMP5. I think these are best settings for size & speed. If any other settings, which can increase speed or decrease size, then let me know.6. How I can do that on global level, I use minimum size setting option, while for three functions, I use max speed setting.

author: rstofer
author_rank: Super Contributor
timestamp: July 03, 2018, 03:00:08 pm
content: Find out if Keil uses Makefiles and if you can edit them. If so, just compile most of the objects with one set of command options and the special case with a different set of options.It would seek to me this question would be better posed on a Keil forum. There are 628 results for a search for 'makefile' at the ARM/Keil site:http://www.keil.com/home/search?searchTerm=makefile
Custom Rigol Boot Screen? - Page 1
Forum section: electronics / beginners

author: ColdWarTom
author_rank: Newbie
timestamp: November 24, 2017, 02:28:18 pm
content: I'm planning to get a Rigol DS1054Z, and I'm recommending it to a colleague who works for a local college. He's happy that it has a Kensington Lock, but he wants to know if they can customize the boot screen to indicate that it belongs to the school. Is this possible? Where do I find out how?

author: bd139
author_rank: Super Contributor
timestamp: November 24, 2017, 03:24:20 pm
content: Best thing is always to carve the owners name into the unit with a soldering iron. If you can replace the boot screen, so can a thief.

author: coppice
author_rank: Super Contributor
timestamp: November 24, 2017, 03:27:50 pm
content: People can sand down and fill what you carve with a soldering iron, and put a sticker over the top. You need to use two part epoxy to bond the scope to the bench is you want some security.

author: ColdWarTom
author_rank: Newbie
timestamp: November 24, 2017, 05:13:34 pm
content: You're preaching to the choir. He's not looking for suggestions. He says changing the boot screen will help him get funding. Try convincing the committee who makes up the rules for getting funding approval.Sent from my iPhone using Tapatalk

author: bd139
author_rank: Super Contributor
timestamp: November 24, 2017, 07:38:27 pm
content: I suggest you get a large fish and hit them with it if that’s how the funding committee is running.

author: PTR_1275
author_rank: Frequent Contributor
timestamp: November 24, 2017, 10:59:45 pm
content: I know you can on the DP832 power supply and I vaguely remember in one of daves videos he had the startup screen as the eevblog logo on his 1054z, however I can't remember ever seeing it in the menus / setup.I have. New 1054z that I just purchased for use at home that I need to set up,I'll have a look and see if it's mentioned anywhere.As we all know, the security stuff will only stop the honest people. As for how the funding department make their choices, I've seen wierder things go on with decision making.

author: ColdWarTom
author_rank: Newbie
timestamp: November 24, 2017, 11:25:43 pm
content: Quote from: bd139 on November 24, 2017, 07:38:27 pmThat sounds perfect! I'm going to leave the fish outside to rot in the sun for a few days, then I'm going to hit them with it! Thanks!Sent from my iPhone using Tapatalk

author: ColdWarTom
author_rank: Newbie
timestamp: November 24, 2017, 11:28:40 pm
content: Quote from: PTR_1275 on November 24, 2017, 10:59:45 pmI appreciate any insight you can offer.I've come to appreciate the honesty of honest people, and recognize that the rest will show their true colors eventually.Sent from my iPhone using Tapatalk
CUSTOM SEGMENT LCD  - Page 1
Forum section: electronics / beginners

author: Fourier15
author_rank: Newbie
timestamp: February 12, 2022, 08:35:05 am
content: Hello folks ,I have an custom segment lcd manufactured from china .Consisting of 59 segment pins and 4 common pins with 1:4 Multiplexed .I have choosed HOLTEK HT1621B to drive my lcd .but the issue is lcd driver contains only 32 segment pins whereas my lcd consist of 59 segment pins ..so can i use two LCD DRIVER to drive my single lcd or i have to use another LCD DRIVER consisting of 64 segment pins like Holtek HT1625 ..Kindly suggest the solution .Thank You

author: Terry Bites
author_rank: Super Contributor
timestamp: February 12, 2022, 01:42:59 pm
content: got any spare io pins on your uC?

author: jpanhalt
author_rank: Super Contributor
timestamp: February 12, 2022, 05:36:56 pm
content: Don't know the details of your LCD driver, but it is not uncommon to have an LCD screen divided between 2 (or more) drivers. One common configuration is to divide the screen vertically. Then select CS1 (pad1 of your controller) for one half and CS2 for the other half (each is active low) when writing to the screen. That method does require an extra MCU pin.Holtec also makes a 64-segment controller (HT1625), which might be easier to use. See dytasheet at DigiKey (or anywhere else).

author: wraper
author_rank: Unknown
timestamp: February 12, 2022, 05:58:16 pm
content: Quote from: jpanhalt on February 12, 2022, 05:36:56 pmBut how are you supposed to share 4 common pins between the two HT1621 drivers? Unless LCD is designed with 2 completely independent halves, or driver IC supporting stacking up, I don't see this happening.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 12, 2022, 06:14:25 pm
content: Perhaps the TS can respond and give a little more information. At a minimum, a link to the LCD datasheet would be helpful.Do you have any constructive suggestions for the TS?
Custom SSD1680 E Ink board - stuck before BUSY/GDR goes active? - Page 1
Forum section: electronics / beginners

author: OrlandoBlyat
author_rank: Newbie
timestamp: April 07, 2025, 11:00:24 pm
content: Hello everyone,I'm encountering an issue prototyping a custom PCB for a 2.13" E Ink display that uses the SSD1680 driver. I could use some advice on what to check next.The firmware for this project was developed and tested successfully on a WeAct Studio SSD1680 module. I'm using the exact same firmware binary on my ESP32-C3 microcontroller connected to my custom board, but the display fails to initialize.The core issue is that the SSD1680 doesn't seem to complete its startup sequence. The GDR (Gate Drive Ready) output signal consistently stays low (inactive), so the external charge pump circuit on my board is never enabled. Consequently, VGH/VGL aren't generated, and the display remains blank.Troubleshooting Performed:Baseline: Verified the ESP32 is running and scope shows SPI signals (SCL, SDA, CS#, DC#) are being transmitted during startup attempts.RES# Issue Identified : Initially, the RES# line was stuck low. My schematic lacked a pull-up. I added a 10kΩ pull-up, and the scope now confirms the ESP32 generates a correct reset pulse (High -> Low -> High).BUSY Issue Identified : After fixing RES#, the BUSY output line appeared to be floating. Checked continuity to the FPC connector. Also added a 10kΩ pull-up resistor here, as one was missing from the schematic.Current Status:RES# pulse is confirmed correct.Initial SPI commands are transmitted after reset.BUSY line reads high (due to the pull-up) but is never actively pulled low by the SSD1680.GDR line remains low.Hardware Notes:My custom board interfaces the ESP32 to the display FPC and includes the charge pump components (L1: 47uH TDK MLZ2012N470LT000, Diodes: Toshiba CES521,L3F, Q1: 2N7002N).I'm aware the L1 saturation current (115mA) and Diode reverse voltage (20V) might be insufficient for full operation, but I suspect the root cause is earlier, as the chip doesn't even reach the stage of asserting GDR or pulling BUSY low.I also swapped my MOSFET, inductor and diodes onto the reference module and the module works - so half rules out the components.Where I Need Help:Since the firmware works on the reference module and the RES# signal is now correct, why is the SSD1680 stalling before it signals readiness by pulling BUSY low? It seems stuck in the very early stages of processing the initial SPI commands after reset.My main suspects are:SPI Communication Problems: Noise on the lines (layout), signal integrity issues preventing the SSD1680 from correctly interpreting the first commands.orPower Supply Instability?Does anyone have any wisdom to help me?Attached are my schematic, layout and the schematic for the reference module.
Custom trace between Ethernet PHY and Switch - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: March 12, 2024, 07:43:29 am
content: This is with respect to my earlier question on LAN8840 PHY and KSZ9567 Switch.Port 6 of the KSZ9567 is RGMII connected to LAN8840.The Module 3 of this errata of KSZ9567 (https://ww1.microchip.com/downloads...cuments/Errata/KSZ9567R-Errata-DS80000755.pdf) states that there's a timing errata with Port 6.The datasheet says the setup time must be a minimum of 2.2ns for Data to clock.The KSZ Ingress delay can only be set to 1.3ns (Note that the register description mentions 1.5ns but it is 1.3ns – Note 6-5 under RGMII timing values).Therefore, using this delay, I still need a minimum additional path delay of 0.9ns to achieve a minimum setup time of 2.2ns.This appears to be tough in PCB for me.For this, I am not using the chip delay on the KSZ9567. I am trying to work on the egress delay with LAN8840 (https://ww1.microchip.com/downloads...s/DataSheets/LAN8840-Data-Sheet-00004727A.pdf) page 49.So, the Plan is to use the LAN8840 fixed 2ns (typ) delay to TXC input as well as add a small (0.2 -0.4ns) Pad Skew delay to make up the 2.2ns min. DS pg 44.Would this be fine?
Custom TV Controller Issues - Page 1
Forum section: electronics / beginners

author: Kdog44
author_rank: Contributor
timestamp: February 09, 2016, 11:04:01 pm
content: For a small weekend project I wanted to build a device that can send a power command to a TV using an IR LED. My target TV is an LG ( model number : 32CL20-UA ). Online, from this sourcehttps://github.com/z3t0/Arduino-IRremote/issues/114, I found that LG TVs generally use the NEC 32-bit standard. I am having trouble determining what the actual command code, in hex, is that I need to send so the TV interprets it as a power signal. Below is a waveform received by a 38.5 kHz receiver. The sent signal was sent by the TVs' remote while the power button is being pressed. Note that the waveform is actually inverted from what was actually sent.

author: uncle_bob
author_rank: Unknown
timestamp: February 09, 2016, 11:48:05 pm
content: HiSet your sample rate on the scope to something that will get you at least 10 samples per bit at the highest likely clock rate. Look at the data with an IR sensor rather than something that is trying to demodulate it. Grab code samples multiple times. Lay them down on top of each other. You will have errors and this will let you spot them.After a bit of looking, you *should* be able to work out a likely clock rate. Go out across 10 or more bits once you have a guess to come up with an accurate number.At that point you can start working out what is preamble and data. Send multiple codes and see what does not change.Yes, this is generalized / start from scratch approach. It does not use any shortcuts. Because of that, it's got a high chance of success.Bob

author: orolo
author_rank: Frequent Contributor
timestamp: February 10, 2016, 01:07:59 am
content: I don't know anything about remote encodings, but a quick search brought upthis. The "pulse length encoding" catched my eye: short pulse = 0, long pulse = 1. The initial very long pulse should be a syncing singal. Decoding the rest: 00100000110111110001000011101111 = 0x20df10ef, 32 bits if I'm not mistaken. Is that right?

author: Kdog44
author_rank: Contributor
timestamp: February 12, 2016, 09:12:25 pm
content: Quote from: orolo on February 10, 2016, 01:07:59 amYes you where totally correct! I was able to write an small function to modulate the data correctly and I got it to work.
Cutting Traces on Metal Core PCB - Page 1
Forum section: electronics / beginners

author: 691175002
author_rank: Regular Contributor
timestamp: December 21, 2015, 07:00:56 pm
content: Has anyone cut traces on a metal core pcb before? Is it safe to scrape at them with a knife or do I risk shorting to the substrate?

author: jmegar324
author_rank: Contributor
timestamp: December 22, 2015, 08:45:50 am
content: There is a risk of shorting when cutting them.

author: made2hack
author_rank: Frequent Contributor
timestamp: December 22, 2015, 09:54:25 am
content: Here's anAL substratePCB I recently ordered.The Copper layer is 2oz (70um) thick. The isolating layer thickness is 100um between Cu and Al. So, unless you can ensure you don't cut past that 100microns, then chances are you will hit the Al substrate.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 22, 2015, 11:53:49 am
content: Disclaimer: I haven't worked the stuff personally.It should be fine as long as you cut on an angle and don't turn up a burr. Don't expect it to hold off much voltage (SELV or so?).Tim
CX-101-BG as current meter on LM723 supply - Page 1
Forum section: electronics / beginners

author: MaggoT
author_rank: Newbie
timestamp: January 10, 2012, 09:15:22 am
content: Hello!I am currently attempting to build a bench power supply around a LM723 and four 2N3055 transistors.I have tested parts of the schematics and things seem to work great so far.However, I have two CX-101-BG panel meters fromhttp://www.circuitspecialists.com/digital-panel-meter-cx101bg.htmlthat I intended to use for voltage and current display. (These are the -BG ones, that should work with a common ground configuration). After a bit of frustration I managed to get one working for straight up voltage measurement using the second example from the datasheet (don't have a schematic for this, sorry), but i cannot get it to measure the voltage across a resistor properly.Here is my power supply schematic, R13 is the resistor over which i intended to measure the voltage drop, and display it on the meter.The "Current limit board" mentioned in the schematic is just another board that switches in various resistors in series to provide a couple of different steps for setting the current limit for the LM723.PSU schematic:So my question is, how do i wire the CX-101-BG up to measure the voltage drop across R13, if it is at all possible? Are any of the COM, INLO, INHI, REL pins internally connected to ground inside the meter?Here is another test i did. The circuit below shows my test setup which is roughly equivalent to what the meter will be measuring inside the PSU.The drop across R2 should be 1.66 volts in this case, and with the divide resistors the CX101 should read about 0.150 volts. However the meter reads out of range...When measuring across R2 with a multimeter i get 2.5 volts, which confirms that the meter is connecting INLO to GND. Grounding COM/RFL or leaving them floating makes no difference. Measuring across R5 with the multimeter i get 0.225 volts.I apologise if i have done some stupid mistake/assumption here, i'm having a hard time getting my head around this, and the datasheet for the meter doesn't really help much.Can anyone give me any tips on how to get this working?Ps. sorry for the long postregardsMaggoT

author: J4e8a16n
author_rank: Regular Contributor
timestamp: August 24, 2012, 01:36:59 pm
content: Dont forget to let us know if you find out how to make it work with a shematic.

author: Rerouter
author_rank: Super Contributor
timestamp: August 24, 2012, 01:46:59 pm
content: i have 2 -bg models working in the common ground config on my own power supply, following J4e8a16n's sheet to the letter ended with it all working for me,

author: J4e8a16n
author_rank: Regular Contributor
timestamp: August 24, 2012, 02:37:27 pm
content: Hi,The shema I seen on the blog use resistors.You did not put resistors? Did you joined the 5678 pins?JP
CX102B voltmeter and ammeter configuration - Page 1
Forum section: electronics / beginners

author: mnmlistmktg
author_rank: Newbie
timestamp: July 17, 2013, 07:18:34 pm
content: Hello All,I'm working on my very first project, a 0-20V variable power supply from an old ATX, and had a question about some meters I installed. The CX102B meters are 5V common ground, so I set one up as a voltmeter and another as an ammeter by measuring across a 1R shunt. The voltmeter, which I installed first, worked perfectly. However, when hooking up the ammeter (which also worked when tested by itself), both meters stopped working.I've gotten it to work (with two new meters) by connecting one of them to a battery instead of the common ground. You can see the schematic here:Anyone have any experience with this? Was it the common ground? Something else I screwed up?Thanks for any input.

author: digsys
author_rank: Unknown
timestamp: July 18, 2013, 12:07:22 am
content: Very hard to understand the circuit, because it isn't clear but - if you don't want to use a dedicated current sense IC, why not put thecurrent sense resistor in the -ve line, then make the junction P/S x Resistor the 0V for both meters, while the other side of the resistorbecomes 0V for the equipment. There'll be a very small error in the voltage meter (0.1V max?), but it will simplify wiring.

author: mnmlistmktg
author_rank: Newbie
timestamp: July 18, 2013, 12:41:20 am
content: Sorry if the circuit wasn't clear... I just put boxes in to represent the two LM317 circuits, one for constant current and one for constant voltage, pretty much right out of the LM317 datasheet. If you click on the schematic, it will take you to circuitlab.com and it's much easier to see.My concern is having both meters on the same common ground... doesn't make any sense to me why that would fry them, but that's what it did (I had them both hooked up to the same 0V out of the ATX). Is there any reason at all why you couldn't hook both meters to the same ground? Just trying to figure out what broke the meters.
Id appreciate input about this RC circuit. Thank you so much :D ! ! - Page 1
Forum section: electronics / beginners

author: renzoms
author_rank: Regular Contributor
timestamp: October 19, 2019, 10:57:35 pm
content: So I got some results that are both correct at some time t and incorrect at other time t. What can you say about the results. The topic is in the bottom right in red.

author: renzoms
author_rank: Regular Contributor
timestamp: October 19, 2019, 11:34:43 pm
content: So I got some results that are both correct at some time t and incorrect at other time t. What can you say about the results.I calculate the Voltage across C1 (V_C1) using a Thevenin EC. Then with that,I got V_R1, I_C1, I_R1, I_Rs, V_Rs (everything on the left half.)So then to calculate V_C2 and V_R2, I used 10 - V_Rs - V_C1 (method 1 "m1.")With V_R2, I got I_R2, henceforth I got I_C2.So using m1 I got some weird results. 10V for V_C2 at t = 0 and -0.1 A I_C2 at t = 0.I'd like to know if there is another way to get V_C2, without using another Thevenin EC.And what do you think I should take away from this experience (the fact that there are correct and incorrect results for V_C2 and I_C2.)Thanks like a lot.

author: renzoms
author_rank: Regular Contributor
timestamp: October 19, 2019, 11:40:49 pm
content: It's affecting my graphs of I and V of C1 and C2

author: rstofer
author_rank: Super Contributor
timestamp: October 20, 2019, 01:30:29 am
content: I just plotted the voltage of the second capacitor over a short time (to see the fast rise near t=0) and a long time to see the steady state.Really, this is a 5 minute thing with LTspiceI added names to the traces and added a trace at the output of the 2 Ohm resistor. The voltage across C1 is not plotted but it is simply the difference between the traces.

author: renzoms
author_rank: Regular Contributor
timestamp: October 20, 2019, 01:45:59 am
content: Thanks dude!I did a Thevenin equivalent circuit, solved it, and then was off by a factor of 10 somehow. I'm happy with the experience though. I appreciate the effort use LTSPICE and offer those graphs!

author: rstofer
author_rank: Super Contributor
timestamp: October 20, 2019, 01:48:58 am
content: Quote from: renzoms on October 20, 2019, 01:45:59 amI changed them a bit. I was going to add a trace of the voltage ACROSS C1 but it's pretty easy to see what it will be.I attached a graph with the voltage across C1 specifically plotted. Note that it charges quickly to some high voltage then drops over time. This is a consequence of the 1mF capacitor looking like a low impedance for a relatively long time.

author: renzoms
author_rank: Regular Contributor
timestamp: October 20, 2019, 05:02:57 am
content: Interesting! I'm very tired so I'm off for tonight. I found where that factor of 10 came from, so the circuit is solved. Thanks again for sharing your graphs. I'll look at it tomorrow, again.
D Flip Flop Ring Counter Multisim - Page 1
Forum section: electronics / beginners

author: markmckee601
author_rank: Newbie
timestamp: April 04, 2015, 08:51:41 am
content: Part of an assignment is to design a 4-bit counter using 4013 D Flip Flops. I've ran into an issue when I try and simulate a standard ring counter where I get a convergence error.Ring counter:http://www.electronics-tutorials.ws/sequential/seq_6.htmlAny help and/or advice would be appreciated!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 04, 2015, 06:07:23 pm
content: Welcome to the wonderful world of SPICE...In short, you need to poke at the parameters in Simulation Settings.For this circuit, you may also need to check the Mixed Sim Settings. Which I think are just ideal vs. realistic pin models.Even when no convergence errors are produced, the code simulator will still fuck up. See this for example:Everything's going along fine, oh wait, notice something missing?...The first lesson on SPICE should be -- and please pass this along to your instructor and/or the rest of class -- YOU AREN'T DRIVING A REAL WORLD REPRESENTATION! YOU ARE DRIVING A MODEL!Once you accept that, you open yourself to the fact that SPICE is a computational environment, and therefore suffers from the drawbacks of any model: convergence, numerical accuracy, sensitivity to parameters, numerical instability or oscillation (particularly in TRAP integration), nonphysical results, and the accuracy of the sub-models your circuit uses (it's very easy to get 40kV from a three-terminal LM741 model -- it doesn't include supply pins -- a five-terminal model may be better behaved, but will still miss the real article in many important ways).Your circuit has the added complication of code models. Digital logic is implemented by a code model (much the way logic circuits for FPGAs and stuff are described in VHDL or Verilog code), which describes events (voltage/state changes), delays, and logic functions (combinatorial and sequential). If an event is missed (particularly when interfacing between the "analog" SPICE model and the digital code model), nothing happens, which is what happened in my screenshot above. Sometimes, it helps to specify ideal pin models (everything stays in the code model, and states don't get corrupted...as easily). Other times, it helps to use real models (which gives better "analog" results). Often, you'll find you have to alternate between them as you make changes in the circuit! (Sensitivity to parameters!)As for your circuit: you have a DC voltage (5V) driving a diode-OR gate into a logic input pin. 1 OR X = 1, so the diodes can be removed and the 5V connected straight to the pin. But that wouldn't be correct with the reference. What's missing is you need to use a VPULSE, not VDC, source. You also need a pull-down resistor so the OR result can ever become logic 0.These changes might well fix your convergence error at the same time, but doing that without talking about what the errors are about, would be unfair.Tim
D-Sub Mixed Contact Connectors: do they have "inserts"? - Page 1
Forum section: electronics / beginners

author: ajikacey
author_rank: Newbie
timestamp: January 04, 2022, 10:40:14 pm
content: Hey all, I'm trying to get this Rubidium clock module working. It has an 11w1 mixed d-sub connector:I'm not very familiar with this connector type. Most of the possible mates I find are missing a central element to connect to the 10MHz output (the most important part!)So I assume there must be some kind of "insert" into these connectors that would allow me to connect the RF signal? Especially since these can be used for either RF or high current applications I guess the idea is you can mix and match. But what would that insert connector be called? I don't know what to google for.(Edit: sorry I can't figure out how to inline the attached images)

author: ajikacey
author_rank: Newbie
timestamp: January 04, 2022, 11:06:45 pm
content: Ah, I think I found what I'm looking for!https://www.digikey.com/en/products/filter/d-sub-d-shaped-connectors-contacts/332

author: tkamiya
author_rank: Super Contributor
timestamp: January 05, 2022, 07:57:52 am
content: I can't find it right now, but I should have a few I can share.You can buy them from DigiKey but it will end up awfully expensive. What I have is sort of a breakout board with the connector. PM me if interested.
D2059 question - Page 1
Forum section: electronics / beginners

author: taco
author_rank: Contributor
timestamp: February 14, 2015, 05:00:14 pm
content: I've tried cross referencing this non and can't find a replacement. Any help? Or suggestions?Thanks

author: Hideki
author_rank: Frequent Contributor
timestamp: February 14, 2015, 05:21:29 pm
content: You left out the all important information about what package it is or what it looks like.I guess it's a 2SD2059 NPN transistor? TO220F?

author: taco
author_rank: Contributor
timestamp: February 14, 2015, 10:38:32 pm
content: Hope this helps. I'm a newbie at electronics so I'm assuming it's an NPN transistor. It fails the test procedure I viewed on the YouTube videos.

author: jlmoon
author_rank: Unknown
timestamp: February 15, 2015, 02:56:52 am
content: All 2sa , 2sb transistors are PNP and all 2sC , 2sD series are NPN2sC are generally lower power higher frequency while 2sD series are the slower work horses for power applications

author: taco
author_rank: Contributor
timestamp: February 15, 2015, 10:13:13 pm
content: Thank you,How do I find a replacement for this transistor since it's no longer available?

author: Rory
author_rank: Frequent Contributor
timestamp: February 15, 2015, 10:17:22 pm
content: Quote from: taco on February 15, 2015, 10:13:13 pmEasy enough:https://www.google.com/search?q=2sd2059+substitute&oq=2sd2059+substitute

author: taco
author_rank: Contributor
timestamp: February 16, 2015, 02:14:26 am
content: I found that substitute, but it says no longer available. It seems no one carries a substitute.

author: Rory
author_rank: Frequent Contributor
timestamp: February 16, 2015, 02:37:25 am
content: Looking at the datasheet for the 2SD2059, it's a general purpose NPN power transistor in a TO220F case.Looking at the NTE website an NTE-54 is their suggested match.http://www.nteinc.com/I found several sellers of 2SD2059 on eBay.

author: taco
author_rank: Contributor
timestamp: February 16, 2015, 03:38:30 am
content: Thanks Rory
D25 Parallel port pinout? - Page 1
Forum section: electronics / beginners

author: Jackster
author_rank: Frequent Contributor
timestamp: August 30, 2018, 05:13:08 pm
content: Am I right in saying that this D25 to D25 has pin 1 through 13 and 14 through 25 reversed on one end?As in pin 1 goes to pin 13, pin 5 goes to 9, pin 15 goes to 24 and pin 20 goes to pin 19?Is this a standard parallel connection?

author: helius
author_rank: Super Contributor
timestamp: August 30, 2018, 05:33:09 pm
content: No. By looking at the back of the shell you cannot see the gender of the connectors, nor the pin numbering. If one connector is male and the other female, it is a straight-through cable (1-1, 2-2, ... 25-25).

author: boffin
author_rank: Unknown
timestamp: August 30, 2018, 05:48:16 pm
content: Somebody already beat me to it, but what you're probably looking at is a plug and a socket, if you plug them together you'll see they all go straight throughThe standard Parallel printer port interface isDB25 Centronics (57-30360 plug)1 1 Strobe2-9 2-9 Data0 -> Data710 10 ACK11 11 Busy12 12 Paper Out13 13 Select In14 14 Autofeed15 32 Error16 31 Reset17 36 Select18-25 19-26 (Grounds)(oh dear god, I just did the pin-pin mapping off the top of my head - some useless knowledge buried in there. I double checked it, but it was right)

author: Jackster
author_rank: Frequent Contributor
timestamp: August 30, 2018, 06:15:46 pm
content: Yep male and female. The photos I was sent showed 2 male ends

author: In Vacuo Veritas
author_rank: Frequent Contributor
timestamp: August 30, 2018, 06:25:51 pm
content: Quote from: helius on August 30, 2018, 05:33:09 pmUh, of course you can. The one with the embossings is the outer hood, this is the male part.https://buildyourcnc.com/Item/electronicsandmotors-connector-male-dsub-DB25-ribbon
DAB Radio Help! - Page 1
Forum section: electronics / beginners

author: Sauron
author_rank: Newbie
timestamp: February 28, 2015, 05:45:16 pm
content: Hello Everyone and salutations from the UK!I got interested in electronics a few months ago and thought I would have a go at fixing my Roberts SolarDAB (V1) radio which was not powering up properly. When plugged in to mains through and adapter I press the power button (It's a soft start button) the screen flashes up with the battery symbol and the speaker makes a 'pop' before turning off again. On the battery it is a similar story, the screen flashes up with the battery symbol but also illuminates before popping and turning off again although this happens less often, but still quite frequently. Playing with the switch a bit and holding it down will eventually turn it on normally though . I thought that the power switch might be a membrane switch and a piece of dirt might have lodged itself between the contacts but it turned out to be just a normal momentary switch. I have noticed that there are two diodes on the power supply board that are getting quite warm, not sure if that is normal though. I have also checked the power supply voltage, all normal (9.5V) I think in the mean time I might try replacing the switch and see if it was just a faulty one. If I were more confident I would do more probing around with a multimeter or oscilloscope but don't want to fry anything.Sorry I don't know much about the problem, but if you have any general troubleshooting tips please let me know as well as any ideas on what the problem might be.Many thanks in advance,Max

author: German_EE
author_rank: Super Contributor
timestamp: February 28, 2015, 06:21:25 pm
content: First rule, look around, especially for suspect solder joints and bulging capacitorsSecond rule, check voltages. Look at some of the chips on the PCB and then download a datasheet to see what the supply should be. An example, on a 3,3V chip 3.2V will probably be OK but 2,5V may not be.Now with those datasheets check the power on reset(s) (a recent video of Dave's on the door intercom may help here). Try powering up the radio without the display backlight connected just in case this is causing a problem.

author: Hydrawerk
author_rank: Super Contributor
timestamp: February 28, 2015, 06:47:01 pm
content: Please post a picture of your radio. Is it this?

author: Sauron
author_rank: Newbie
timestamp: February 28, 2015, 07:53:06 pm
content: No, I believe mine is the first version, I also had a brief look for schematics and things like that, seems like no-one has any...And thanks for the tips German_EE! I have made progress, I decided to do some testing, turns out on battery it works every time (Tested 100 times(!)). I tried a different power supply and that made no difference and I also tried a identical switch, still made no difference plugged in. I'll begin probing around the board now.

author: Hydrawerk
author_rank: Super Contributor
timestamp: February 28, 2015, 11:24:44 pm
content: It looks like it was made in cooperation with Sangean. Some Roberts radios even look like current Sangean models.