hybridfree/eevblog-posts huggingface dataset:
OSH Park DRC for Altium - Page 1
Forum section: electronics / beginners

author: kcs
author_rank: Regular Contributor
timestamp: April 28, 2014, 09:10:45 am
content: I am just starting with Altium. I want to create a PCB using OSH Park service. OSH Park does provide DRC file for Eagle. Unfortunately, Altium is not capable to import it. I am wondering, maybe someone has already created all the necessary rules in Altium and could share the .rul file?

author: kcs
author_rank: Regular Contributor
timestamp: April 30, 2014, 01:24:07 am
content: Bump.

author: Teledog
author_rank: Regular Contributor
timestamp: April 30, 2014, 04:03:30 am
content: OSH Park typically only confirms your layout, your CAD should do your DRC.Upload your gerbers to OSH and their website will let you know ASAP if the files are valid (no, you don't have to pay to test your file uploads)
OT(?), HP Hewlett Packard 3468A for 130$ including in't ship - Page 1
Forum section: electronics / beginners

author: eevblogfan
author_rank: Frequent Contributor
timestamp: June 11, 2012, 08:26:07 pm
content: oh well , I've seen that deal and I am considering buying it , the meter is used self test OK ,seller has 98% positive feedback ,what do you think ?thank you in advance !

author: Unknown
author_rank: Unknown
timestamp: June 15, 2012, 11:45:37 am
content: A fine meter, assuming it's in good condition. Price is a little bit on the high side for within the US, might be OK for your country depending on where you live. Overseas shipping can easily cost $40-50.

author: eevblogfan
author_rank: Frequent Contributor
timestamp: June 15, 2012, 12:44:00 pm
content: that's indeed the case ,but I can't buy him anymore, UPS killed my budget !!!

author: eevblogfan
author_rank: Frequent Contributor
timestamp: June 15, 2012, 12:48:09 pm
content: if any one whant to , just offer him and he will accepthttp://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=110872187563&ssPageName=ADME:X:AAQ:US:1123#ht_2271wt_1132have anice shopping
Other options for spring-type vibration sensor-switch - Page 1
Forum section: electronics / beginners

author: jolshefsky
author_rank: Regular Contributor
timestamp: March 30, 2016, 01:43:44 pm
content: I'm working on a little project that might go to manufacture, so I'd like to find a way to turn it on for a short time (see myother post about the timing circuitry if you're at all interested.) My first crack is using a tactile switch but I'd like to make it consumer-grade waterproof so having a moving part on the outside seemed like a bad idea. Then I remembered those spring-type vibration sensor-switches which use a coiled spring around a center pin; when it's jarred, the spring makes contact with the pin.I found what I think istheChinese manufacturer, Bailin Electronics Company a.k.a. BeeLee withthis kind of offering. I'm hoping, against all odds, to find a manufacturer I can put a modicum of trust in to have good labor and environmental practices, neither of which I think I can find in China. But more important, I'd like to find a reflow-ready surface-mount solution, and perhaps one with actual force specifications (as opposed to "high sensitivity", "standard", "dull", and "duller" which is worse than useless.)I haven't found anything on DigiKey or Mouser—only ball-type tilt sensors or piezoelectric tilt sensors. Any idea where else I could look?
OTP Programming the AEAT-6600-T16 - Page 1
Forum section: electronics / beginners

author: anvoice
author_rank: Frequent Contributor
timestamp: March 25, 2018, 05:48:08 am
content: I know OTP mode stands for One Time Programming, and the application note I'm reading reading says the AEAT-6600-T16 is a "One Time Programmable ASIC". My question is: does the "One Time" mean once only period, or can you once again connect the higher OTP voltage (it takes 6.5V) and reprogram the chip, just not during normal operation? I'd like to experiment with several different encoder resolutions and modes, and would like to know whether I'll need a bunch of chips for that. Thank you.

author: anvoice
author_rank: Frequent Contributor
timestamp: March 25, 2018, 06:56:07 am
content: For example, because AMS is out of stock most places I ckecked...My AS5048 from Digi-Key is set to ship sometime in July I think. Another reason is the 16-bit resolution on the AEAT, although that comes with what could be prohibitively slow response time.Thanks for the clarification, I thought that's what it probably means but wanted to know for certain.
Ouput Impedance Calculation and circuit adaptation for Class D Amplifier - Page 1
Forum section: electronics / beginners

author: elefurtronik
author_rank: Regular Contributor
timestamp: April 10, 2023, 10:35:12 am
content: Hello,I am trying to create a class D audio amplifier. I have an input audio signal between 174Hz-494Hz.I found a schematic on the internet and I would like to adapt this circuit to my usage. I have an 8. speaker.I will put an LC filter to the output of the half-bridge rectifier. I found the website below to calculate LC values. However, I need the INPUT impedance.How can I calculate the input impedance?https://util01.industrial.panasonic.com/ww/utilities/ds/lc-sim/

author: wasedadoc
author_rank: Super Contributor
timestamp: April 10, 2023, 11:39:45 am
content: 1. There is no half bridge rectifer.2. The output impedance is close to zero. Just use that value.3. The mean output voltage is half of the supply. You will need a dc blocking capacitor between output and speaker.

author: elefurtronik
author_rank: Regular Contributor
timestamp: April 10, 2023, 11:56:36 am
content: Quote from: wasedadoc on April 10, 2023, 11:39:45 amPlease find my answers in the quote.

author: wasedadoc
author_rank: Super Contributor
timestamp: April 10, 2023, 12:06:40 pm
content: To me it is just a push-pull output. I can understand how it looks like one half of a H-bridge. It was your inclusion of "rectifier" that I disputed.The capacitor need to be in series with the speaker. Doesn't really matter which end of it.

author: elefurtronik
author_rank: Regular Contributor
timestamp: April 10, 2023, 12:16:06 pm
content: Quote from: wasedadoc on April 10, 2023, 12:06:40 pmHow can I calculate this capacitor value in theory according to this schematic?

author: wasedadoc
author_rank: Super Contributor
timestamp: April 10, 2023, 12:22:13 pm
content: Same as you would for any audio amplifier. The C and speaker are a high pass filter which needs to be adequate for the lowest audio frequency you want. (NOT the PWM frequency.)
outdoor junction-box and opensource sprinkler controller - Page 1
Forum section: electronics / beginners

author: Kdub454
author_rank: Newbie
timestamp: July 03, 2017, 08:25:07 pm
content: I recently bought a double, outdoor-rated junction box to house a non-permanent sprinkler controller I bought online.Ideally, the whole project (5V power supply and all) would be mounted inside the junction box, with a power cord (re-purposed outdoor extension cord) running back to an outdoor outlet.*So I have three questions:1.) Is permanently tying the power supply (a gutted apple 5V wall wart) to an extension cord a bad idea, and if so why?2.) Is it a bad idea to include the power supply in the junction box instead of at the outlet, and if so why?3.) Is using mains power and low-voltage electronics in one of these reasonable for a semi-permanent outdoor project? (it would be moved inside during off-season)*In case one (or all) of these is a bad ideaDon't worry, nothing has been implemented yet - I'm still just in the design phase. I wanted to use this as an opportunity to learn about electronics.Any suggestions or recommendations are appreciated.

author: sokoloff
author_rank: Super Contributor
timestamp: July 03, 2017, 09:39:28 pm
content: Your sprinkler controller is likely going to "want" to have 24-ish volts of AC to run the valves anyway. (There are DC valve solenoids, but 24VAC is more common.)Given that, I'd run a 120VAC to 24VAC transformer someplace dry, then carry the 24VAC across the yard, underground, whatever you need to do, and near the project box turn that into whatever your project needs. That could be another transformer, bridge rectifier, and linear supply, or a switching supply, depending on your interest in selecting or building the various options.I would not run 5VDC over a long run (due to voltage drop concerns). This is much less a problem when starting with 24V than 5V, of course.As for having high and low voltage in the same box, it's done all the time and can be done safely, but if you can manage for your box to take only 24VAC, almost every safety concern you have goes out the window, plus it happens to be what you're going to want to switch with relays to send out to each zone box anyway.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: July 04, 2017, 12:59:26 am
content: A couple further suggestions:A junction box is far better than an outlet box as the junction box provides no ingress of moisture via the outlet.Put your wire entries on the bottom of the box only. Make gravity your friend.Use cable glands rather than connectors if at all possible.
Output capacitor ripple - Page 1
Forum section: electronics / beginners

author: Ohm_My
author_rank: Contributor
timestamp: February 09, 2020, 02:25:14 am
content: I'm a young player here, as Dave says, and fall into traps on occasion.I've been viewing some of Dave's older videos about measuring PS ripple and noise. I have a commercial generic step-down voltage regulator (5v) and have been trying to measure the ripple with my scope just for my satisfaction.In several other videos I see that it is "best practice", I guess, to take the measurement across the output capacitor. This is easier said than done as I am dealing with a 0805 package sized cap. I think Dave would use the "bee's dick" size standard. I'm also using the little springy thing for the ground on my probe as to avoid minimizing any stray signals.Given the size of the capacitor and trying to position the probe correctly on the cap while making scope adjustments would make even an ordained priest swear. My question is can I make the measurement across the actual voltage output and ground solder pad locations? What is the advantage of measuring directly off the cap itself?I appreciate any comments.

author: langwadt
author_rank: Super Contributor
timestamp: February 09, 2020, 03:46:24 am
content: the output is what matters

author: Cubdriver
author_rank: Unknown
timestamp: February 09, 2020, 09:08:49 am
content: Yes, you can take the measurement across the output.-Pat

author: Siwastaja
author_rank: Super Contributor
timestamp: February 09, 2020, 11:21:54 am
content: Yes, the idea with the small spring clip thing is to avoid creating a long wire loop with the oscillosscope's ground alligator clip. Output connector itself is what matters, that's what you use anyway, so you can measure there.The suggestion of measuring over an output capacitor makes sense when you measure a power supply of an integrated product, so that there is no output connector, the supply output being connected directly to the rest of the circuitry on PCB. Then, the output capacitor is a logical place to get the most accurate ripple figure of that power supply part.
Output Image to 40 pins eDP from Arduino. Possible? - Page 1
Forum section: electronics / beginners

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 09, 2020, 01:46:06 pm
content: is there a hope showing pictures to 2K or 4K eDP LCD from Arduino without FPGA or some fancy IC? using simple discreet elements such as transistor or level shifter etc is acceptable. the frame rate is of no concern. if the control only can show a frame every 1-10 seconds so be it. the main point what is the simplest, easiest (to learn) and the cheapest way? so long i can see a picture...

author: MasterT
author_rank: Frequent Contributor
timestamp: July 09, 2020, 02:59:25 pm
content: Define an arduino. Nucleo-H743 from STM has arduino style pin-header & supports by arduino IDE.DS:"The devices embed a HDMI-CEC controller that provides hardware support for theConsumer Electronics Control (CEC) protocol (Supplement 1 to the HDMI standard)."

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 09, 2020, 05:56:54 pm
content: Quote from: blueskull on July 09, 2020, 01:59:26 pmhmm the nightmare is actually real. i havent read eDP spec or manual, i was just hoping there is no minimum clock speed, i guess the same to HDMI or LVDS. if someone can link eDP protocol/spec i will appreciate it. i saw a guy promoting his open source arduino HDMI shield but he seems not to put it on sale.. if i can have that then i can use it to connect to the eDP board that accepts HDMI input. the aim here is to get the cheapest solution to transfer an image from sd card to mcu (arduino) to 2K or 4K screen.

author: newbrain
author_rank: Super Contributor
timestamp: July 10, 2020, 10:54:12 am
content: Quote from: MasterT on July 09, 2020, 02:59:25 pmHDMI CEC is a slow one wire interface (open drain with pull up) to exchange commands and status information between HDMI source and sinks on the HDMI cable, e.g. to start a stop a player from the TV remote.Each bit is about 2.6 ms, nothing to do with video signals.
Output impedance/resistance of a op-amp follower - data sheet - Page 1
Forum section: electronics / beginners

author: Chris_PL
author_rank: Contributor
timestamp: February 18, 2014, 09:52:26 pm
content: Hi to all helpful souls,Being a semi-pro on digital side of things I'm a complete newbie to analog design (on a hobbyist level), esp. when it comes to interpreting gazillion of values on analog parts data sheets.The question is - I need to roughly estimate the output resistance/impedance of an op-amp configured as gain=1/buffer/follower. There's a voltage divider at the output using 0.1% resistors, so I would like to know where to look on the data sheet/what to calculate from it, so I could tweak the "upper resistor" value of the divider to be overall as close to "exactly what I want" as possible?Or maybe the "low output resistance" in op-amp theory means in real world parts really, really low, in the order of single Ohms, not let's say tens or hundreds of them?Signal is pretty low frequency, let's say DC to 100Hz tops. And yes, I know that hooking any load on the output of divider would mess it somewhat, but the load is known, so there's no problem with that part.

author: w2aew
author_rank: Super Contributor
timestamp: February 19, 2014, 03:06:50 am
content: Quote from: Chris_PL on February 18, 2014, 09:52:26 pmThe negative feedback, closed loop effectively makes the output quite low (because the output adjusts to whatever's necessary to null the input voltage difference). Of course, there are output current limitations, and that is certainly in the data sheet. What is your load impedance.
Output pulse shape - Page 1
Forum section: electronics / beginners

author: elki
author_rank: Regular Contributor
timestamp: April 18, 2024, 12:44:53 pm
content: I am sorry but I have a very newbie question. I have some circuit from which I get the two types of outputs, depending on how I look at it with an oscilloscope. In the first case it is just directly connecting to the output through a very big resistor without any load. In the second case, I use 1k to ground. Obviously, the first case is problematic, because I am basically capacitively read the output without any load. However, this is the shape that I want. Could you please suggest a proper way of arranging the output stage to get the pulse shape as shown in the first case?

author: jwet
author_rank: Frequent Contributor
timestamp: April 18, 2024, 02:41:00 pm
content: Can you put some numbers on these waveforms, especially time and maybe give other details. I'll try to answer with what's given...The first case looks like a high impedance source, something like a 10k output impedance. Its not affected by 100k (likely 100k with 10 meg in series from the scope). You should be able to just use a 10x scope probe- the 100k isn't doing much. It might be isolating the direct cap load of the probe...The second case is pretty confounding- it doesn't look possible. The first pulse is what you might get with a capacitively coupled output, the width of the pulse is a few RC's but the second pulse is somewhat impossible from a linear circuit, it rises before the output rises then follows it down. This is non causal and suggests some kind of triggered delay from the rising edge - not linear. A classic under cap coupled output would have the the first edge create a pos pulse and the second create a neg pulse.

author: elki
author_rank: Regular Contributor
timestamp: April 19, 2024, 07:08:01 am
content: Thank you. Here is an example of the problem I am dealing with.I have a high impedance input signal on R1. I am trying to convert it to a low impedance output on R2. Obviously, if I further reduce the input current by increasing R3, my output voltage on R2 becomes zero. Naively, I thought that the proper way of dealing with it would be to have an op amp buffer placed in-between R1 and R2, but somehow it does not work. Does anyone have a suggestion? The input signal is about 10-20mV.

author: Andree Henkel
author_rank: Regular Contributor
timestamp: April 19, 2024, 01:04:51 pm
content: What is Purpose of R2?If you want to drive coaxial cable with 50Ohms WaveImpedance with signals of high enough frequenzy or short enough rise / fall timesand you want to correctly source terminate?Then R2 needs to be in series to the output, not to ground

author: xvr
author_rank: Frequent Contributor
timestamp: April 19, 2024, 01:49:10 pm
content: Quote from: elki on April 19, 2024, 07:08:01 amIt's impossible. No any passive network can convert high impedance input to low impedance without loosing signal power a much.Quote from: elki on April 19, 2024, 07:08:01 amExactly. And may be even without R1 & R2
Output voltage bridge rectifier  with smooting capacitor higher - Page 1
Forum section: electronics / beginners

author: robsims
author_rank: Frequent Contributor
timestamp: November 20, 2022, 11:35:18 pm
content: Hi, before rectifying an AC voltage coming from a transformer, my DMM reads 7,53 volts AC. After connecting a bridge rectifier and a smoothing capacitor my DMM reads 9,86 volts DC across the capacitor. Why is the voltage higher?

author: wasedadoc
author_rank: Super Contributor
timestamp: November 20, 2022, 11:47:59 pm
content: Quote from: robsims on November 20, 2022, 11:35:18 pmWhen reading AC the DMM is displaying the RMS value. For a sine wave the peak is 1.4 (square root of 2) times the RMS value. The rectifier charges the capacitor to almost the peak voltage.

author: robsims
author_rank: Frequent Contributor
timestamp: November 21, 2022, 02:22:09 am
content: Quote from: wasedadoc on November 20, 2022, 11:47:59 pmMany thanks. I knew it had something to do with the capacitor, because without the capacitor, the reading across the output from the bridge rectifier is 6,37 volts
Output Voltage minimal Changing - Flexiforce Sensor Issue - Page 1
Forum section: electronics / beginners

author: Rocky Richi
author_rank: Newbie
timestamp: April 02, 2025, 12:39:31 pm
content: Hello everyone,I'm working on an electronics project that uses a flexi force sensor A201 , INA333 instrumentation amplifier and esp32 module ,and I've simulated the circuit using lt1167(in place of ina333), changing the resistance value(in place of sensor) and used behavioural voltage source (in place of adc value conversion on esp32) in LT spice.However, I'm running into an issue:when I apply force to the sensor, I observe minimal step variation in mV range in the LT1167's output voltage and no or minimal step variation on bv source valuesWhat I Have Tried So Far :1.Tried to invoke the ina333 spice models but simulation was not behaving properly.2. hence used lt1167 built in library ina which is present on ltspice platform.3. I updated circuit to resolve the issue by adding capacitors to ensure the noise is the problem.4. Later I checked for the different voltage levels but no change.5. Later I thought voltage divider may be problem and hence removed it but no effects.6. also changed r2 value and gain r3 value but it just increased the output voltage swing and bv source value.7.Also employed the opamp to provide the stable buffer to ref pin.Are there any circuit modifications or additional components that could help enhance the sensitivity of the circuit?Any suggestions would be greatly appreciated !

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: April 02, 2025, 12:50:46 pm
content: Have you implemented the circuit in real life or seeing this phenomena in simulation only?

author: Rocky Richi
author_rank: Newbie
timestamp: April 02, 2025, 01:38:31 pm
content: Before implementing on hardware part I need to verify the circuit is correct or not

author: jwet
author_rank: Frequent Contributor
timestamp: April 04, 2025, 01:25:12 pm
content: Ref should be tied to your DC output reference unless your INA handles this internally.

author: Rocky Richi
author_rank: Newbie
timestamp: April 06, 2025, 06:49:16 am
content: ok will try

author: Poroit
author_rank: Frequent Contributor
timestamp: April 06, 2025, 08:32:18 am
content: G'day Rocky Richi,Correct me if I am wrong but I assume your sensor is a Dynamic type.Can yousuccessfullysimulate an output change with that type of sensor?I did some amplifiers repairs for some PHD students a few years back who were measuring force.They were trying to get the amplifier to respond by loading up the sensor with weights.It only worked when you hit it with a hammer.
OVC3860 battery charger - Page 1
Forum section: electronics / beginners

author: Retch
author_rank: Newbie
timestamp: September 30, 2016, 08:12:02 pm
content: Hi,i got the blk-md-spk-b with the OVC3860 chip. It's a nice chip, but now I want to charge a 200mah battery. At this page they say i have to connect the battery to VBAT and GND. Yes the chip is running. To charge the chip they say connect 5v + to CHG and 5v - to GND. But when I connect the 5v, the chip turns of. That means music stops playing immediantely and power consumption is 0ma. What is wrong? Can you help me? Have a nice day
Over current at switch on - Page 1
Forum section: electronics / beginners

author: Crockett
author_rank: Contributor
timestamp: May 01, 2013, 09:11:37 pm
content: Greetings from the "meeting place" state, Tennessee.I recently turned on my newly acquired oscilloscope and it promptly blew its mains fuse.I removed the fuse and checked the current. Initially the current jumps when the switch is flipped; but it quickly comes down well under the fuse rating amperage. The required fuse is a 0.5A slow blow 100-115 V 50-60Hz. The fuse I found in it was a 0.5 A, but not a slow blow.My question is should I just replace the fuse with the appropriate slow blow and not worry about it, or should I do that and also look for what and why the unit briefly draws more than the 0.5 A when switched on??Thanks,DavidLeader LBO-514

author: c4757p
author_rank: Super Contributor
timestamp: May 01, 2013, 09:20:48 pm
content: It's charging up its capacitors. Almost everything takes an inrush when you turn it on; that's why they specified a slow fuse in the first place.

author: Crockett
author_rank: Contributor
timestamp: May 01, 2013, 09:44:34 pm
content: Yes, I just was wondering if the initial charge up was designed to be that much or if through age they have come to draw more. I guess if I just put the correct fuse in it I'll find out.Thanks.David

author: w2aew
author_rank: Super Contributor
timestamp: May 02, 2013, 12:37:48 am
content: Quote from: Crockett on May 01, 2013, 09:44:34 pmJust as c4757p stated, the manufacturer wouldn't have spec'd a slow-blow if it wasn't required.

author: c4757p
author_rank: Super Contributor
timestamp: May 02, 2013, 12:47:14 am
content: Quote from: Crockett on May 01, 2013, 09:44:34 pmI recently coupled a 54W transformer through a rectifier to 28mF of capacitance and it takes over 16A inrush when I turn it on. The initial charge up is indeed supposed to be huge.

author: Crockett
author_rank: Contributor
timestamp: May 02, 2013, 08:34:57 am
content: Well, I've got new, correct fuse installed now. So, hopefully I won't be coming back to this thread reporting it not working.Thanks for the comments and any more are, of course, still welcome.David
Over voltage protection and reverse polarity protection - Page 1
Forum section: electronics / beginners

author: roogadget
author_rank: Contributor
timestamp: September 26, 2018, 05:17:10 am
content: My specs are 9V - 15V.My project requires Over voltage protection and reverse polarity protection.What is the "best" way to do this for a simple project?Do I design a circuit to check for this or do i just go with a chip that handles it??

author: JPortici
author_rank: Super Contributor
timestamp: September 26, 2018, 09:21:22 am
content: PTCC + TVS may be a very simple solution, need more information

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 26, 2018, 12:37:47 pm
content: Nominal load 1mA or 1kA?Overvoltage of 16V or 16kV?Reverse of -1V or -1kV?Is it a slow swell, fast transient, lightning surge, nuclear EMP?Once you know the voltage, current and time scales of the system, methods become apparent.Tim

author: Neilm
author_rank: Super Contributor
timestamp: September 27, 2018, 06:39:55 pm
content: Is this a personal project, or does it have a commercial application? If the latter, does it have to meet any standards, for instance automotive standards?

author: Brumby
author_rank: Unknown
timestamp: September 28, 2018, 02:24:28 am
content: As above ... More information needed.

author: 6PTsocket
author_rank: Regular Contributor
timestamp: September 28, 2018, 11:07:28 am
content: Not knowing your exact situation, a diode for reverse voltage protection and some simple 3 pin voltage regulator that handles a wide enough range of input voltage. As mentioned above, you need to be more specific for more specific suggestions.Sent from my SM-G900V using Tapatalk
Over voltage protection not working - Page 1
Forum section: electronics / beginners

author: mitrynicolae
author_rank: Contributor
timestamp: November 03, 2019, 03:24:27 pm
content: Hi everyone,Let me explain the issue first. I try to design a protection on the inputs of a differential amplifier. At first I did not paid much attention to details and I only develop the circuit from the Figure1. Everything worked fine until the voltage drop to 5V or bellow. From this step on the measurement is useless. Please ignore the voltage offset, it was due an incorrect resistor, and it can be easily fixed.My suspicion of the incorrect measurement goes on the zenner diode and its leakage current.Anyway I was not happy with the protections so I have tried to design another circuit dedicated for this purpose. The issue is that regardless how hard I am struggling I cannot fulfill all the specifications. These are:- voltages between 0 and 20V should pass unaltered (or with minimum distorsion of any sort)- if input voltage is above 20V the output should be either shut down or clamped but in any situation the input voltage should not get to the opamp- if the input voltage is somehow reversed then the output should be shut down.- the protections should not use any external power supply (so using a relay and a monitoring circuit is out of option)- optional, the circuit should contain the minimum parts possible.Again as I previously said, no mater how hard I struggled I cannot find a valid solution for the above problem. For example using a P channel mosfet as reverse voltage protection will not work for low voltages.
Overall voltage swing for DC-DC converters in series - Page 1
Forum section: electronics / beginners

author: slcf2003
author_rank: Newbie
timestamp: September 07, 2021, 03:11:48 pm
content: Hi, I'm trying to understand a schematic that I found online. The author managed to get a +26.5V to -26.5V swing using three DC-DC converters. Two RO-0524S (https://www.digikey.ca/en/products/detail/recom-power/RO-0524S/2314954) are used to generate +-24V and a similar ROL-0505S is for a 5V, and connecting them in series gives the desired voltages. The input voltage of these three converters are all 5V.Please find the attached schematic. Also I think the 27.5V in the schematic is a typo.My questions are:1. Why are the outputs of U42, the middle converter, +2.5V and -2.5V. not +5 and 0? Is it because the circuit is symmetric?2. Is it true that this voltage swing is achievable because the outputs of these three converters are isolated from the input 5V and GND?3. If question 2 is true, does it mean that this is not achievable by replacing with switch-mode boost converters?Thank you.

author: David Hess
author_rank: Super Contributor
timestamp: September 07, 2021, 07:00:49 pm
content: Quote from: slcf2003 on September 07, 2021, 03:11:48 pmI do not know why and it is not because the circuit is symmetric. Maybe there is a rail splitter off to the right somewhere?QuoteThe outputs are obviously galvanically isolated from the inputs.QuoteThe common non-isolated boost converter would not work in this application. The converters need to have isolated outputs.

author: slcf2003
author_rank: Newbie
timestamp: September 08, 2021, 02:21:02 am
content: Hi David, thank you for your help.QuoteThe voltages are then fed to opamps as power rails, and I don't see a rail splitter there. Does the voltage swing of +26.5V to -26.5V or 53V difference make sense? Maybe all the author wanted was to generate such a isolated voltage difference for another part of the circuit.
Overcurrent SSR relay for master-slave switch - Page 1
Forum section: electronics / beginners

author: dumbelectric
author_rank: Newbie
timestamp: March 21, 2025, 07:23:09 am
content: I need to turn on/off my circulation pump (max 100W, 230V AC) in sync with master circulation pump which is inside of a air to water heat pump. Do such things exist? I could find on aliexpress a mechanical realy, not SSR and sensitivity should be better (~30mA minimum turn on current) and it should have an external current transformer.I am planning to put this device inside heat pump, there is no place for DIN rail, but I can put something about 3-4 cm height.Heat pump has Shimge APM25 circulation pump controlled by PWM, but I could not find any datasheet about PWM control.Alternatively I could read PWM signal sent to pump (or received from pump, it also sends status PWM signal to controller) with arduino and turn on/off my slave pump with Omron 2A SSR relay I already have. Is it safe to attach arduino input in parallel to PWM inputs/outputs of shimge pump?My heat pump controller does not have a function which supports glycol-water heat exchanger, so I need master - slave configuration.Any ideas welcome.One more method of controlling slave heat pump would be of temperature rise/drop on heat exchanger, let's say if temperature drops/rises >1C per minute, then we need to turn on slave pump.Heat pump is based on PC4003-G board, it has many outputs not used, but I cannot find any datasheet about that board too.Any ideas?

author: Jeroen3
author_rank: Super Contributor
timestamp: March 21, 2025, 09:50:26 am
content: You can use a master/slave relay that operates on sensed current. They are commercially available with plugs, standby switches they are sometimes called.But can also be easily put together with controls, eg: current window relay.Best thing though would be to use an available channel in the heat pump controller. Often they need to be supplemented with an external pump when the internal one cannot provide not sufficient flow.I don't think you need to "enable" a external pump channel. I would assume one would be set so by default.However, heat exchangers can also work independently, as many underfloor heating manifolds systems do.

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: March 21, 2025, 09:52:37 am
content: You can read the PWM Signal with an Arduino. If the PWM signal is higher than 5V, step it down to 5V for the Arduino. Use an optocoupler to provide isolation and read the PWM safely. Measure the duty cycle with Arduino (pulseIn() function).https://docs.arduino.cc/language-reference/en/functions/advanced-io/pulseIn/

author: dumbelectric
author_rank: Newbie
timestamp: March 21, 2025, 11:01:28 am
content: There are contacts "to booster circuit pump for heating", but installer manual does not say anything about it.Manual says "If an external water pump is needed, connect the power cord to the water pump terminals." It not clear is it the same "booster" pump or not.
Overdrive the blue colour in RGB in-line hardware mod - how can I do it? - Page 1
Forum section: electronics / beginners

author: wirysage
author_rank: Newbie
timestamp: November 21, 2018, 03:31:16 am
content: Hi All,How can I overdrive the RGB blue colour in-line over a component video cable? Is there some sort of hardware mod or small circuit I could make to overdrive it? A video effects box is like over $1000, surely there is a easier way to do this?Thanks!

author: Ian.M
author_rank: Super Contributor
timestamp: November 21, 2018, 03:55:24 am
content: There are specialist OPAMPs with enough bandwidth for video, but its not easy even if you have RGB component video with seperate sync and the odds are it wont work well unless you only need a small boost, as its likely to overload the blue input of the monitor.OTOH it should be possible to attenuate the R and G signals and turn up the brightness and contrast on the monitor to get a similar result.RGB with sync on green would be quite a bit harder - you'd probably need a sync seperator then reinsert the sync after attenuating the green.If you've actually got YPbPr video its a real mess of complex analog circuitry to do what you want: convert to RGB with separate sync, boost the blue then reconvert back to YPbPr.

author: macboy
author_rank: Super Contributor
timestamp: November 21, 2018, 01:57:12 pm
content: Quote from: wirysage on November 21, 2018, 03:31:16 amWhat problem are you trying to solve by over-driving the blue?

author: tooki
author_rank: Super Contributor
timestamp: November 22, 2018, 12:29:42 pm
content: Quote from: macboy on November 21, 2018, 01:57:12 pmIndeed!! The OP sounds like a classic X-Y problem.
Overlay Components in Altium - Page 1
Forum section: electronics / beginners

author: GTV31
author_rank: Newbie
timestamp: November 08, 2014, 11:09:16 pm
content: Hello to everyone,I would like to ask this question because I have not found any answer to it.How can I overlay two components in Altium, without a design rule error?I can imagine that it has to be something related to the design rule: ComponentClearence or Hight, but I do not manage to make it possible without generating an error.I am using a standart 12AU7 footprint of altium and a standart 2 pin header as a footprint for the LED (I have also tried the standart LED footprint and the same resut)My goal is to place a LED under a Vacuum Tube.Thanks to everyone for helping me.Kind regards

author: Jeroen3
author_rank: Super Contributor
timestamp: November 09, 2014, 12:00:38 am
content: You probably interfere with a 3d body, or you're inside the components keepout area.

author: GTV31
author_rank: Newbie
timestamp: November 09, 2014, 12:07:06 am
content: Well both components don't have 3d body, and when I select Keep-Out layer, those components do not have anything

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 09, 2014, 01:45:48 am
content: "The LED"?The correct answer is, you don't. Because only stupid products do that.But yes, if there is 3D information, Altium resolves collision based on that... if there's none, it just checks the outlines.Another purpose might be, assembly variants where you might want to try several options for inductors or resistors in a given spot, say. In this case, you can have intersecting 3D bodies as well, if you assign the assembly variants so the components are exclusive to a given variant.Tim

author: BradC
author_rank: Super Contributor
timestamp: November 09, 2014, 03:16:08 pm
content: Quote from: GTV31 on November 08, 2014, 11:09:16 pmYou probably can't. What you can do is add a design rule that disables the offending check for those specific parts. I do it quite often when I've set liberal clearance rules to make home etching easy, but then place a part where the footprint or routing contravenes those rules. Just make an exception for that rule on that part.

author: gxti
author_rank: Frequent Contributor
timestamp: November 09, 2014, 07:32:16 pm
content: If you add 3D bodies for both parts, and adjust them so they don't overlap or come closer than the 3D body clearance rules allow, then there will not be a violation. If a part does not have a 3D body then it implicitly occupies the rectangle around the footprint up to some large height, so you don't have any control over vertical clearance.
Override Switch for Relay Circuit - Page 1
Forum section: electronics / beginners

author: vidarr
author_rank: Frequent Contributor
timestamp: May 05, 2024, 06:48:05 pm
content: I want to have an override switch for a relay circuit that switches whatever state the circuit is in, to the opposite. So, if the relay is "on" and a pump is running, you can flip the toggle switch and the pump will turn off. If the relay/pump is off, you can flip the toggle switch and it turns the pump on.Basically, it is just a fast, very easy way to control a single device that is connected to a larger system with multiple appliances without affecting the rest of them, or having to plug/unplug anything.Can someone please look at my schematic and see if I got it correct?Thanks!

author: themadhippy
author_rank: Super Contributor
timestamp: May 05, 2024, 07:19:05 pm
content: looks wrong,get rid of the wire from com to the switch center pin ,also remove the 2 wires you've shown from the switch to pump,the pump connects to the switch center (assuming its the common) pin

author: Ian.M
author_rank: Super Contributor
timestamp: May 05, 2024, 07:26:53 pm
content: The concept is probably fatally flawed! Do you really want the Arduino to think its turned the pump off, but instead its really on?How about an alternative: Take a small SPDT center off switch, Wire its moving contact to Arduino Ground, and its fixed contacts to the relay driver transistor base, and collector. When the switch is cantered (off), the Arduino has normal control of the pump. Flick it one way to ground the base and the pump is forced off. Flick it the other way to bypass the transitor, and the pump is forced on.
Overriding resistor divider output - Page 1
Forum section: electronics / beginners

author: Gizmo
author_rank: Regular Contributor
timestamp: April 07, 2016, 10:53:52 pm
content: If I have a resistor divider, like this:Which is interfacing a ROM output enable from a 5v system to a 3.3v FLASH, can I then drive the LDOE# output from the divider from another TTL source to override this signal? I believe I can do this ok.The idea here is that the divider provides a bring-up signal for the boot ROM if the CPLD in system flash fails, the LDOE# normally being provided by the CPLD, which optionally overrides the ROM at this address and switches in some RAM.

author: dacman
author_rank: Frequent Contributor
timestamp: April 07, 2016, 11:30:43 pm
content: Where is the other TTL attached? I believe that it could be driven from a high to a low, but I don't think that most TTL devices could override a low to a high.

author: Gizmo
author_rank: Regular Contributor
timestamp: April 08, 2016, 08:30:47 am
content: Quote from: dacman on April 07, 2016, 11:30:43 pmIt will be driven by a CPLD, most likely a MachXO2. A couple of options... I could then pass this through a 10k resistor to make it a weak pull up / down, but I'm not sure how badly this will affect rise time. Or the other option is to pass these signals through a 5v tolerant LV245 and have the output enable connected via a weak pull down to the control line of the CPLD.I think the latter option sounds the safest. Although the read cycle from ROM1# to data being required is like 280ns, so I might get away with the series resistor...
Overvolt input protection  - Page 1
Forum section: electronics / beginners

author: JustMeHere
author_rank: Frequent Contributor
timestamp: February 25, 2020, 02:53:07 am
content: So I just hit the wrong button on my bench power supply and switched from 5v to 30v. (Don't ask how because there is a safety to prevent this.) Needless to say I made the magic smoke.What's a good and cheap way to protect my circuit? I found an IC, but I was wondering what is best. Simple MOV? TVS diode? I'm looking for opinions with pros and cons.

author: digsys
author_rank: Unknown
timestamp: February 25, 2020, 03:36:33 am
content: I've always just used a polyfuse and pretty much any of the above, depending on how accurate a voltage you want to allow. All have some sort of temp / current / time variation. IF you want it exact and instant, then a VRef device and SCR (plus the poly) is by far the best option.

author: Ian.M
author_rank: Super Contributor
timestamp: February 25, 2020, 05:02:22 am
content: Quote from: digsys on February 25, 2020, 03:36:33 amA classic 'crowbar' circuit. See fig. 22 in theT.I. TL431shunt regulator datasheet. N.B. The TL431 crowbar is not well suited to operation at low supply voltages as the TL431 tends to have an on-state Vak of 2V or higher depending on the current, so there isn't much headroom to reliably trigger a SCR on a 3.3V rail. If you can tolerate a 3.6V trip threshold it should be workable, but if you need to crowbar lower voltage rails than 3,3V look elsewhere.
Overvoltage and reverse voltage protection ICs for 5V, 3.3V, 2.5V rails - Page 1
Forum section: electronics / beginners

author: silicon_ghost
author_rank: Contributor
timestamp: April 12, 2015, 10:52:11 pm
content: Digging around the web and here at EEVBlog, I see plenty of different ways to attack reverse polarity protection combined with overvoltage protection. I've seen some complicated multi-discrete part circuits as well as recommendations to just buy an off-the-shelf chip. After a dozen hours of searching via Google and wandering Mouser/Digikey, I'm beginning to think "I don't know what I don't know".Desirable traits:work well for 3.3V or 5V rails (does not have to be same part number)low on resistance or voltage drop (this precludes diodes)minimize # components and no BGA designs (other SMD ok)lower cost is always better, $5 for the components at qty 10 is a targetactually be stocked at Mouser or DigikeyI don't need:Battery managementCurrent monitoring (can be handled with a PTC fuse on input)The P MOSFET for reverse polarity becomes an issue with <=3.3V rails since the the gate drive voltage could leave a high RONvalue in the linear region. Overvoltage protection seems to turn into a pile of discrete transistors and diodes.I found this Maxim 4866L (Mouser link,Datasheet). It requires a complementary MOSFET or 1P/2N channel MOSFETs to function (page 1 and page 8 of datasheet). It has a built in charge pump to solve the low gate voltage problem. The undervoltage lockout is a bonus. Unfortunately the series is offered only with overvoltage trip levels of 7.4, 6.35, 5.8, and 4.65. The 5.8 V is perfect for 5V USB but the series does not go low enough.The Maxim chip is the only such beast I've been able to find. I can't figure out what my search terms should be or if maybe I'm chasing a non-existent part. I can't seem to get to a usable parametric search and have to browse hundreds of parts manually and nothing close the Maxim chip showed up so far. I want a simple low cost solution that I can re-use in multiple board designs. Am I approaching this problem correctly?
Overvoltage, Overcurrent and Reverse Polarity Protection IC (BQ24308) - Page 1
Forum section: electronics / beginners

author: EAvMx
author_rank: Newbie
timestamp: July 26, 2021, 01:59:30 pm
content: Hello everyonehow can I choose a correct PMOS? I've read in a Design Guide corresponding to this chip that Si2343DS PMos would do the job but it doesn't explain how they chose it.Thanks!!

author: tooki
author_rank: Super Contributor
timestamp: July 26, 2021, 05:34:27 pm
content: Quote from: EAvMx on July 26, 2021, 01:59:30 pmDatasheet says:QuoteI doubt it's particularly critical, beyond the points mentioned there. The Si2343DS seems like a nice little modern low-RDS(on)MOSFET, but I think anything remotely comparable should work fine, as long as the minimum voltage limits above are met.
Overwhelmed by number of FET drivers. looking for recommendations - Page 1
Forum section: electronics / beginners

author: cbc02009
author_rank: Regular Contributor
timestamp: May 11, 2018, 07:08:18 pm
content: Hello All,As I've posted previously, I'm working on a solar panel controller for a class project. My portion is the buck converter that inputs the voltage from the panel and outputs the correct voltage for the battery.The number of mosfets and mosfet drivers on digikey is frankly overwhelming, and I really don't know where to start other than picking one at random (is that what people do?) I was hoping someone could throw me a couple of recommendations of parts that maybe they've used in the past, just so I have somewhere to start.Or maybe there really isn't much difference between them? In that case, is there a brand you prefer?The only real constraint so far is that it be able to switch at ~100Khz. I think I need it to be high-side, as well (at least, that's how I've designed it.)The mosfet is easier for me to find, since I can narrow the listings down on digikey quite a bit, but recommendations would also be appreciated. including safety margins, I'm looking for something that can handle ~4A and ~25V. I was thinking something like this:https://www.digikey.com/product-detail/en/stmicroelectronics/STD150N3LLH6/497-8889-1-ND/2071115although it might be overkill.Thanks!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 11, 2018, 09:00:19 pm
content: If you need bootstrap, I forget which ones are high current output, search around. HIP2101, IR2110, not too bad.TC442x series are pretty typical for higher current (low side) drive, up to 18V. There's an improved IXYS (IXxxxx) version too. For higher voltages and currents, there's the IXDD614CI and relatives. The cost goes up as you go into higher currents, and IXYS in general.Tim

author: cbc02009
author_rank: Regular Contributor
timestamp: May 11, 2018, 09:28:53 pm
content: Quote from: T3sl4co1l on May 11, 2018, 09:00:19 pmThank you so much! I will take a look at those data sheets!

author: cbc02009
author_rank: Regular Contributor
timestamp: May 11, 2018, 10:09:31 pm
content: Quote from: T3sl4co1l on May 11, 2018, 09:00:19 pmYeah, the IXYS looks like massive overkill for this project. The HIP2101 look like exactly what I'm looking for though. Thanks again!