hybridfree/eevblog-posts huggingface dataset:
1kV 0.1mA regulated power supply feedback layout question - Page 1
Forum section: electronics / beginners

author: epkoncept
author_rank: Newbie
timestamp: October 23, 2023, 04:46:51 pm
content: Currently I am experimenting with a ~ 1kV DC-DC inverter used to power photomultiplier tubes. Current is low, 0.1mA or so. My feedback is a 1G ohm with a 220k or so trimmer at the bottom to provide thefeedback voltage of about 0.6V to the regulator circuit. Since the impedance of the feedback network is so high, I think it is susceptible to noise ingress. I was wondering if there are hints as to how to do the physical layout ? e.g., should the divider network be located next to the regulator circuit and the HV and gnd leads brought back there ? I think that having the divider network next to the output and then having a shielded lead bring the feedback signal to the regulator would pick up more noise than the former ? My goal is to have the ripple in the 1~ 2mV range. I am stuck with ripple in the 10~20mVpp range with a larger 60Hz ripple that is being picked up. Filtering the feedback voltage kills the loop response.P

author: epkoncept
author_rank: Newbie
timestamp: October 23, 2023, 05:02:57 pm
content: my scribbled schematic.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 23, 2023, 05:47:59 pm
content: Ideally the FB divider should be closer to the regulator - but ideally this also has a short link from the HV to the divider.There shoould be a good shield around the circuit, so 60 Hz ripple should not come in very much.If possible the divider should not be all the way down to 0.6 V, but use a higher reference voltage. If needed a negative ref (e.g. -5 V) instead of GND in the divider. This make the divider output even higher impedance, but still not more sensitive to pickup of hum.If the divider is too high impedance, one could use parallel capactors. A capacitive divider does not cause power loss and does not add noise, at least for the AC part. DC drift is still set by the resistor part though.The supply to the boost regulator still should be well regulated, not to get ripple from there.

author: epkoncept
author_rank: Newbie
timestamp: October 23, 2023, 06:47:05 pm
content: Kleinsteinthanks for the commentsCan't do much about the reference voltage its fixed to 0.6V in the MT3608 boost converter.Interesting that you mentioned a capacitive divider. I haven't used those in +30 years. Last time I saw them in use were in CRT TV set designs.May be the next step is to mock up the design in a shield enclosure to see if my 60Hz ripple is due to the unshielded proto or due to my measurement set up.P
1MHz Oscillator using op amp - Page 1
Forum section: electronics / beginners

author: mathk
author_rank: Contributor
timestamp: February 18, 2013, 01:31:02 am
content: Is it possible to design a 1Mhz sine wave oscillator using op amp?According to some App Note from TI it is only possible design oscillator up to a couple of Khz with op amp. But if you take high speed op amp like some Analog Device "AD8055" which have a slew rate of 1400V/us and a 300Mhz -3dB bandwidth I am wondering if we can design oscillator that goes up to a couple of Mhz with it?Also advice on designing such oscillator are more than welcome.Thanks.

author: c4757p
author_rank: Super Contributor
timestamp: February 18, 2013, 02:40:14 am
content: Try it!

author: fcb
author_rank: Super Contributor
timestamp: February 18, 2013, 01:01:00 pm
content: Of course you can design a 1MHz oscillator with an opamp.One method might be a "phase-shift oscillator" (google it), the values are quite reasonable (220pF/300R) - i'm assuming that you want a simple oscillator with a sine out?

author: JVR
author_rank: Regular Contributor
timestamp: February 18, 2013, 01:38:58 pm
content: Just use a Xtal as a reference.

author: mathk
author_rank: Contributor
timestamp: February 20, 2013, 01:21:15 am
content: Yes @fcb simple sinusoid is what I need. I have try the "Wien bridge oscillator. I set the frequency at about 900KHz but the problem is that I have more a square wave than a sine wave and the frequency is jumping from 950 to 960 KHz (measured with a rigor 100Mhz bandwidth scope).Then I tried a simple LC oscillator and the output is much cleaner, I still have a square wave but filtering the output give me what I need.Any suggestion to increase stability?Thanks

author: fcb
author_rank: Super Contributor
timestamp: February 20, 2013, 01:40:35 am
content: It's in the nature of the Wien for it's amplitude to grow until clipping. You need some form of amplitude stabilisation - bulbs used to be used.Once you've sorted the amplitude out, then tackle the f-instability. Just be careful that it actually exists, and not some artifact of the Rigol.
1n4007 blew apart like fuse - Page 1
Forum section: electronics / beginners

author: algorithm
author_rank: Regular Contributor
timestamp: June 24, 2022, 10:07:52 am
content: Been trying to repair a switch mode power supply. Just noticed that a 1n4007 diode was blown in twain like a fuse on secondary side. Hadnt seen that before. Does anybody have any ideas what I should suspect caused this? It was a catastrophic failure, took out a power transistor, a 1.6a fuse, I thought the bridge, but datasheet said it has 1v vf. And that diode. Im hoping nothing else. On the primary side I had cobbled a 4.7uf 200v cap using 4- 50v in series. And left the other cap in as I didnt have 82uf at 200v and it was within 20% on capacitance and acceptable esr I thought. But I really dont know what caused it. I guess bad caps but although the caps age was old they looked good. Unfortunately no schematic and its a busy board. Its for a jvc vcr.

author: algorithm
author_rank: Regular Contributor
timestamp: June 24, 2022, 11:49:57 am
content: I think the diode was replaced, why I used a 4007 I dont recall, probably misinformation while googling and poor assumptions, emphasis on ass. But the diode replaced has this printed on it"339"What kinda diode do that be?It has .1xx drop on dmm.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: June 24, 2022, 01:28:00 pm
content: 1N4007 is a very slow diode and it is not suited for power supplies. (especially reverse recovery time).If that other diode is <200mV (or even below 400mV) then it's almost certainly a schottky diode.Schottky diodes are usually very fast, which is good for SMPS circuits.https://en.wikipedia.org/wiki/Schottky_diode#Reverse_recovery_timeSchottky diodes can also be too fast, which leads to higher EMI, coupling issues and other nastyness.An old but very good read is "AN25 switching regulators for poets"Another good magic word is "hot loop". Put that in a search engine and read some articles.
1N4148 and 10R resistor in parallel, any way to test diode? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: December 15, 2018, 09:28:51 pm
content: I was wanting to check some out of circuit diodes, but they are each paralleled with a 10 ohm resistor. Is there any fairly straightforward way to test if the diode is fine without splitting it from the 10R resistor? And to check the 10R hasn't shifted much? Thanks

author: capt bullshot
author_rank: Super Contributor
timestamp: December 15, 2018, 09:39:10 pm
content: You can check the 10R resistor using a common Ohmmeter, I suppose it'll apply a rather low current (like 1mA to 10mA). So the voltage across the resistor stays well below the diode forward voltage.For testing the diode, you could apply a constant current of 100mA that would cause 1V drop across the resistor. With diode in parallel, the voltage drop will be lower, approximately the diode forward voltage at 60mA ... 70mA (0.6V ... 0.7V).

author: Brumby
author_rank: Unknown
timestamp: December 16, 2018, 12:00:19 am
content: .... and the reverse voltage will be 1.0 VThe 1N4148 is a signal diode, not a power one, so it's important to keep the current down. 100mA is ideal.

author: spec
author_rank: Frequent Contributor
timestamp: December 17, 2018, 08:29:27 am
content: Quote from: capt bullshot on December 15, 2018, 09:39:10 pmC L E V E R

author: Chris Wilson
author_rank: Super Contributor
timestamp: December 18, 2018, 02:08:56 pm
content: That works fine and will save me a lot of time, many thanks
1n6478 equivalent - Page 1
Forum section: electronics / beginners

author: multiplier
author_rank: Contributor
timestamp: March 31, 2013, 09:37:28 am
content: Hi there!I need a DIP Package diode which has the same characteristics as the 1n6478-84 series. 6478-84 is surface mount and can't be implemented on bread boards. I couldn't find any equivalent on my own. Can anyone out there help me?

author: Rerouter
author_rank: Super Contributor
timestamp: March 31, 2013, 09:42:50 am
content: from what i can see (datasheet is pretty limited on any specs) its a 1A general purpose diode, so unless a more detailed datasheet is linked to, i would say a 1N4004 will suit as a replacement for the breadboard,

author: multiplier
author_rank: Contributor
timestamp: March 31, 2013, 10:03:05 am
content: The thing is, this diode also works at 10 kHz. 1n4001-4007 series aren't fit for high frequencies.

author: multiplier
author_rank: Contributor
timestamp: March 31, 2013, 10:08:30 am
content: How about the specs on this page?http://www.vishay.com/diodes/list/product-88527/

author: Rerouter
author_rank: Super Contributor
timestamp: March 31, 2013, 10:31:20 am
content: where exactly does it say that? 10Khz is pretty bloody slow, and just about every other spec including the capacitance matches up... as they are both standard speed general purpose diodes? neither is made for a fast recovery time?i also have used 1n4004's as clamping diodes for about 10Khz with no issue so I'm quite curious where you found your info?

author: Unknown
author_rank: Unknown
timestamp: March 31, 2013, 11:49:28 am
content: The 1N400x series have a very slow reverse recovery, which means they suck for rectifying 10 kHz. For clamping diodes, you don't care about reverse recovery, but only about turn on time, which is much better. So 'works at 10 kHz' is a bit vague.I don't see any turn on / off specs in the Vishay 1N6478 datasheet, so I wouldn't rely on it to perform any better.

author: SeanB
author_rank: Super Contributor
timestamp: March 31, 2013, 12:25:54 pm
content: If you want a slightly better diode use the UF400x series, which have a better recovery time, but are pretty much a drop in replacement for the 1N400x diodes. A little faster but still quite capable.

author: multiplier
author_rank: Contributor
timestamp: April 01, 2013, 06:20:50 am
content: All my observations are based on the response of the circuit while simulating in Multisim. A diode with a fast recovery time is required for rectifier application and the 1n4001-07 series miserably fails. I have no idea as to how the 6478-84 series worked, but it worked. MAX474 is the op-amp that I am using. I am facing the dilemma of finding a suitable DIP Package replacement for this series.
1P+N MCB - Page 1
Forum section: electronics / beginners

author: incognito1
author_rank: Newbie
timestamp: September 29, 2020, 06:20:25 am
content: For what applications, shall 1P+N MCB be installed instead of 1P or 2P MCB?

author: Zero999
author_rank: Super Contributor
timestamp: September 29, 2020, 11:22:37 am
content: When complete isolation is required, on a single phase circuit.

author: incognito1
author_rank: Newbie
timestamp: September 30, 2020, 03:01:41 am
content: when is it a must to install a 1P+N instead of a 2P?
1S Lipo Charger/Discharger - Page 1
Forum section: electronics / beginners

author: FrankT
author_rank: Regular Contributor
timestamp: September 20, 2017, 09:01:31 am
content: I have a plethora of tiny 1s Lipo batteries from mini helicopters and quadcopters.I'm looking for a charger that can charge, discharge, and analyse them (voltage drop under load, max current, do they match their ratings eg 45C discharge), with low charge rates from 50-400mA.Before I start trying to build my own, I'm wondering if there is anything like this on the market, or something I can re-purpose - a general purpose charger, that I can reprogram.From what I have seen in sample schematics, I just need a simple buck converter circuit with current and voltage monitoring, and a microcontroller to manage the LiPo charge requirements. And a controlled load to discharge at various rates.

author: xani
author_rank: Frequent Contributor
timestamp: September 20, 2017, 11:03:08 am
content: I have this one:http://www.ebay.co.uk/itm/EverActive-LC-2100-Aku-charger-1-2-pcs-Li-ion-3-6V-3-7V-/122390498941It does charge/discharge and calculates battery ESR. Only 500mA/1A work so you'd have to modify it for smaller ones. I haven't teared down so I dunno if that has some dedicated chip or it can be easily hacked

author: BradC
author_rank: Super Contributor
timestamp: September 20, 2017, 01:00:44 pm
content: I use a SkyRC IMAX B6. Does a great job.I wrote a little daemon that logs and generates a web page so I can monitor the unit from a web server.I use it for anything from small lead acids to my plethora of cheap RC lipos.

author: BenKenobi
author_rank: Regular Contributor
timestamp: September 20, 2017, 06:03:11 pm
content: I use the same charger for all my LiPo's, it has been faultless, not expensive really either.Don't bother with some of the cheaper plug top 1s chargers, I've had batteries cooked by chargers that don't regulate or shut off properly.
1st IC - Page 1
Forum section: electronics / beginners

author: insurgent
author_rank: Regular Contributor
timestamp: April 21, 2011, 05:34:31 am
content: Just going through the old parts bins and came across the first IC I ever bough. I purchased it while in a Radio Shack with my grandfather (WWII Midway pilot and Ham radio operator) in Northern California having no idea what it was. It was also the same summer that Star Wars Episode 3 came out! Date code: Week 10 (February) of '73 (or October?)!

author: smackaay
author_rank: Regular Contributor
timestamp: April 21, 2011, 06:14:12 am
content: The first IC I ever got was back in like '85. Still have it. It was an LM566. Pretty cool chip actually.
2.4 GHz receiver with ADC output - Page 1
Forum section: electronics / beginners

author: paranoid_emailer
author_rank: Newbie
timestamp: February 28, 2014, 10:24:23 am
content: Hi,I am looking for a 2.4 GHz receiver chip that outputs baseband digital I/Q data, with a sampling rate of around 40 MSPS.I realize that most SDRs output digital data, but the ones with large enough sampling rates tend to be expensive (~$400 for bladeRF, ~$800 for the Ettus USRP) and cover a much larger frequency band than I need. The receiver chips I've found are either:a. designed for certain modulation schemes (e.g. ADF7242) with no way of accessing the ADC outputs, orb. very expensive and cover a much larger spectrum than I need (e.g. AD9361, LMS6002D)Do there exist 2.4 GHz receivers with ~40MSPS ADC outputs that are reasonably cheap (< $50)? Alternatively, how difficult would it be to design one myself (someone who knows nothing about microwave circuits) in a few months?Thank you.

author: marshallh
author_rank: Unknown
timestamp: February 28, 2014, 07:43:47 pm
content: Do they exist? Sure. Are they cheap? No.

author: Kryan9
author_rank: Contributor
timestamp: February 28, 2014, 09:38:21 pm
content: There are options, but "Cheap" depends on how lucky you are at getting it right on the first try of DIY.If you want a relatively narrow band with your own software solution, you could try emulating the HackRF approach with a Maxim Wifi Transceiver. These would convert 2.4 GHz down to the baseband, where you throw on your own ADC/DAC solution with a microcontroller/FPGA and you're good to go.Probably would run around 100-150 USD minimum based on where I'm from, though, so I don't know if that would fly with you.

author: paranoid_emailer
author_rank: Newbie
timestamp: March 01, 2014, 11:40:10 pm
content: Kryan9, thanks for the tip regarding the Maxim WiFi receivers - I was not aware those had baseband outputs. Unfortunately, it seems the evaluation boards for those chips are exorbitantly priced. I might be better off getting a bladeRF instead...

author: rfbroadband
author_rank: Unknown
timestamp: March 02, 2014, 04:34:30 am
content: don't even think about AD9361. ADI does not even support medium volume customers (I mean companies) with that chip.... not to mention a hobby project

author: paranoid_emailer
author_rank: Newbie
timestamp: March 03, 2014, 09:55:08 pm
content: Thanks, rfbroadband. Would I find sufficient resources if I get the USRP (which has an AD9361 front-end) instead?

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 04, 2014, 01:58:24 am
content: What about hack a WiFi card? There are some with open source drivers and well documented hardware.

author: rfbroadband
author_rank: Unknown
timestamp: March 04, 2014, 05:36:32 am
content: Quote from: paranoid_emailer on March 03, 2014, 09:55:08 pmWell, Ettus is selling the USRP. I assume they have to provide some support to their customers. I don't know what kind of software and APIs they provide, so I would hope using the USRP it would not be necessary for you to program the AD9361 directly. You could request their documentation before you purchase the USRP.....
2.4GHz antenna replacement - Page 1
Forum section: electronics / beginners

author: IvoS
author_rank: Frequent Contributor
timestamp: September 07, 2020, 01:41:23 pm
content: I have ALIGNA10 transmitter(RC hobby) which I believe is rebranded FUTABA that transmits on 2.4GHz.The antenna on the radio broke off. The quick fix would be to replace it with 2.4GHz antenna with a SMA connector as for examplethis onefound on Amazon.or this one. The question is: is it OK to pick any 2.4GHz antenna and it should work or do I have to look for some other specifications? Thanks in advance.

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 07, 2020, 11:44:08 pm
content: double post not allowed...https://www.eevblog.com/forum/rf-microwave/2-4ghz-antenna-replacement-253060/msg3223080/#msg3223080
2.4tft mcufriend display  - Page 1
Forum section: electronics / beginners

author: mskumar84
author_rank: Newbie
timestamp: July 24, 2017, 11:37:38 am
content: hii am planning to interface 2.4tft lcd to msp430 pls help me to proceed further

author: Jeroen3
author_rank: Super Contributor
timestamp: July 24, 2017, 11:49:27 am
content: You should be a lot more specific with your question. Otherwise everyone just assumes you have mistaken eevblog.com for google.com.

author: mskumar84
author_rank: Newbie
timestamp: July 26, 2017, 04:42:06 am
content: hii am using msp430f447 in my project i am planning to interface 2.4tft lcd of mcufriend company .... i want to know the flow of itwith regardssenthil

author: danadak
author_rank: Super Contributor
timestamp: July 26, 2017, 11:00:51 am
content: Lots of google hits on "mcufriend" and libraries.Here is one that shows a solution for the codeing required. You might haveto port it.http://forum.arduino.cc/index.php?topic=286790.0Google "mcufriend msp430", also a few hits on others work.Regards, Dana.

author: Rerouter
author_rank: Super Contributor
timestamp: July 26, 2017, 11:07:37 am
content: also be aware that there are many different display controllers, so depending on your exact model of display, certain example code may not work.

author: mskumar84
author_rank: Newbie
timestamp: July 28, 2017, 11:22:31 am
content: thank u i am working on it

author: kathy
author_rank: Contributor
timestamp: August 22, 2017, 10:33:39 am
content: For 2.4" TFT LCD module, there are RGB interface, MCU interface, SPI interface available. the interface could be custom made.most of 2.4" TFT are QVGA resolution, with 240RGBX320 dots.
2.54mm Connector and 1.27mm Connector  - Page 1
Forum section: electronics / beginners

author: cobramostar
author_rank: Contributor
timestamp: July 26, 2021, 08:51:25 pm
content: I have never worked with this programI am interested in whether it is possible to select two different connectors and that it automatically connects the pin to the pin1-1, 2-2, ............if anyone has the time and will to explain in detail how to make this pcb

author: Nusa
author_rank: Super Contributor
timestamp: July 27, 2021, 12:30:51 am
content: What program? You left that detail out.But in general, you'll have to connect the nets between pins before you can use any kind of auto-routing feature.

author: varunkoganti
author_rank: Contributor
timestamp: July 27, 2021, 02:37:24 am
content: Its just an adaptor kind of thing, it converts 2.54mm pitch headers to 1.27mm pitch headers.I made something like this for my st-link, mine converts (2rows 10 contact)20pin 2.54mm pitch headers to (2 rows 5 contacts)10 pin 1.27mm pitch headers.Please find the link, maybe this would help you.Note - I used SMT headers for mine, the attached one used THT headers, I am referring to the 1.27mm headers.I hope this is helpful.https://github.com/DarkStarLab/ST-Link-V2-Debugger-20-10-Adapter

author: cobramostar
author_rank: Contributor
timestamp: July 27, 2021, 01:26:05 pm
content: Quote from: varunkoganti on July 27, 2021, 02:37:24 amcan i open your fillets in kicadfor my needs it should edit because both connectors are 180 degreesyou see connector 2.54 adapted to 1.27, but I don't understand which wires you use to connect with 1.27, I already have 1.27 on the jtag connector, I thought to adapt it to 2.54 because it's easier for me to use zise to connect it to jtagi would like to do something similar as in the picture Connector_1.27_too_2.54.png

author: cobramostar
author_rank: Contributor
timestamp: July 27, 2021, 05:01:29 pm
content: Quote from: Nusa on July 27, 2021, 12:30:51 amcan you explain how to insert the connector and how to connectwhich options to usethank you

author: cobramostar
author_rank: Contributor
timestamp: July 27, 2021, 09:32:12 pm
content: Quote from: cobramostar on July 27, 2021, 05:01:29 pm

author: jpanhalt
author_rank: Super Contributor
timestamp: July 27, 2021, 11:11:14 pm
content: I have been following this thread and still am not sure exactly what you want to do. For example, do you want pin to pin identity with simply a different pitch? Is each pin considered separately or are several pins tied together? Those are not the only questions.In sum, provide a schematic of what you want to do.

author: perieanuo
author_rank: Frequent Contributor
timestamp: July 28, 2021, 06:04:21 am
content: connecting 20-40 ping between 2 connectors in any schematic/layout software takes less than this debate, it's pointless unless you wanna connect 2500 pin connectors and script it
2.5" tft monitor - Page 1
Forum section: electronics / beginners

author: arekm
author_rank: Unknown
timestamp: February 06, 2013, 08:56:55 pm
content: Hi,I'm looking for a 2.5" tv or monitor (with video input, so driver needs to be included) with a good resolution.Best would be 640x480 but I guess that's nearly impossible to buy. Real 320x240 would be fine, too (as 320x240 == 320x240xRGB pixels).Any recommendations?

author: Zad
author_rank: Super Contributor
timestamp: February 06, 2013, 11:58:12 pm
content: Adafruit stock a 320x240 one:http://www.adafruit.com/products/912

author: MikeK
author_rank: Super Contributor
timestamp: February 07, 2013, 01:21:46 am
content: You can get them on eBay for quite a low price.

author: Skimask
author_rank: Super Contributor
timestamp: February 07, 2013, 01:31:22 am
content: Yep, search TFT rearview monitor.If you Google around a bit, you'll find a handful of pages out there talking about how they don't NEED to run on 12v and a bit of hackery will get a few of them running on 3.3v no problem.

author: jaqie
author_rank: Regular Contributor
timestamp: February 07, 2013, 01:52:07 am
content: if you dont need a housing, and are ok with tearing apart a unit, this looks good at first glance?http://www.amazon.com/MONITOR-COLOR-CAMERA-TESTER-OUTPUT/dp/B005FIX5FE
2.8 to 5v amplifier HELP - Page 1
Forum section: electronics / beginners

author: fox3d
author_rank: Newbie
timestamp: March 26, 2016, 01:43:11 am
content: Hi guys,I have been following EEV blog from the beginning, but this is my first postcould somebody help me to build 2.8v to 5v amplifier/converter?I have to amplify square wave signal from 2.8 to 5 or 6v. I have tried with arduino but delay was too big even if i used direct port commands.I know it is simple but I cant wrap my head around and i don't want to blow up expensive equipment that's why I'm asking pros hereThanksfox

author: michaeliv
author_rank: Frequent Contributor
timestamp: March 26, 2016, 02:05:35 am
content: Some questions to help give better answers:Where is the signal coming from, where is it going to ?What power sources do you have in your system ?Is it a digital signal or analog signal ?What frequency range is the signal around ?

author: tautech
author_rank: Super Contributor
timestamp: March 26, 2016, 02:08:58 am
content: Quote from: fox3d on March 26, 2016, 01:43:11 amWelcome to the forum.Level shifting IC or Translator is what you need.Here's a few:http://www.nxp.com/products/discretes-and-logic/logic/level-shifters-translators:MC_29482?cof=0&am=0&tab=Products

author: fox3d
author_rank: Newbie
timestamp: March 26, 2016, 02:33:33 am
content: Signal is digital 20Hz to 90Hz. And it is going also to digital after its amplified so the other device can read it. Power source which is available is 24v 2.2A.But I can use converter 24v to 5v. Or use 24 to drive opamp. I'm kinda scared to use 24v in case of failure. So the 24v don't go to signal input. To me the safest way is to use opto relay. But those have too much of a delay.

author: michaeliv
author_rank: Frequent Contributor
timestamp: March 26, 2016, 03:31:41 am
content: Your 5v thingy might recognize 2.8v as logic high. Check the datasheet if that is the case. If it is, you can connect it directly.I assume that you already have the 5v converter in your system, and won't need to add one just to get this 5v signal.Use the one on the left here :https://pbs.twimg.com/media/A7g86KCCQAAgwds.jpgPerhaps also increase the resistor value to 10k.It's converting 3.3v to 5v, exactly what you want.This will also work, if you prefer MOSFET's :

author: Zero999
author_rank: Super Contributor
timestamp: March 26, 2016, 10:46:47 am
content: The frequency is low enough that a simple transistor would work. You've mentioned the delay but not said what's acceptable?Doe it matter if the signal is inverted?If not, the 74HCT04 will do and is very easy yo get hold of.http://www.nxp.com/documents/data_sheet/74HC_HCT04.pdfIf it needs to be non-inverting then you could use two of the 74HCT04's not gates in series or the 74HCT34, which isn't so widely available.https://www.engineering.uiowa.edu/sites/default/files/ees/files/NI/pdfs/00/53/DS005359.pdfThe 74HCT series needs a 5V power supply, which can be obtained from the 24V supply, using the LM7805.
Delete Delete Delete - Page 1
Forum section: electronics / beginners

author: The_Almighty_Bacon_Lord
author_rank: Contributor
timestamp: February 24, 2016, 10:00:11 pm
content: Delete Delete Delete

author: michaeliv
author_rank: Frequent Contributor
timestamp: February 25, 2016, 12:19:58 am
content: Converter:http://www.ebay.ca/itm/-/281291753628Or find a similar, more powerful one.As for if you can drain that much without damaging it it depends on the battery. You need to draw ~3A from it, it should be fine with most cells. Every battery comes with a 'C' rating, Multiply capacity by C to get max current draw. Ex 2200mah * 1.5C = 3.3A max draw.

author: michaeliv
author_rank: Frequent Contributor
timestamp: February 25, 2016, 01:09:14 am
content: Oulps, you actually want a complete USB charger module that would both charge the LI-ion when supplied with 5v and output 5v when working on batteries ?The link I provided only does the latter half ( it outputs 5v when supplied with input voltage from the battery ).Simply connect the battery to the input, adjust the potentiometer so the output shows 5v, and proceed to draw 2A @ 5v.If you want a complete solution the cheapest way to go is to re-use the internals from this (It claims to output 2A) :http://www.ebay.ca/itm/-/331643918661http://www.ebay.ca/itm/-/401045504413

author: michaeliv
author_rank: Frequent Contributor
timestamp: February 25, 2016, 04:08:32 am
content: I assume that "LiPo" is a typo since I haven't seen a 18650 LiPo cell, only LiIon.You can use the first link too, even though it uses 4 batteries they are wired in parallel so it's the same as 1 single cell.
2 cell lithium charger IC handsolderable (8.4volt) - Page 1
Forum section: electronics / beginners

author: lk
author_rank: Regular Contributor
timestamp: October 25, 2013, 09:14:06 am
content: Greetings,I'm on the lookout for a 2-cell lithium charger IC, i was using the mcp73864, but i did not realize until it was too late that it had been EOLed, so now i'm looking for something to replace it, i have spend time on the parametric searches in digikey and mouser, it does not really work for me.I'm looking for something that can charge with 0.5A to 1A, something like the tp4056 but for 2 cells, and it has to be hand solderable, with leads, i need the leads, to be able to probe reliable. And something that does not cost an arm and a legA switching regulator would also be ok.http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Prototyping/TP4056.pdfmcp73684 (it says highly advanced, but i guess not advanced enough to get trashed)http://ww1.microchip.com/downloads/en/DeviceDoc/21893F.pdfDoes anyone have a favorite charger IC that would fit these requirements-lk

author: tszaboo
author_rank: Super Contributor
timestamp: October 29, 2013, 06:58:31 pm
content: There you go:http://www.linear.com/product/LTC1731-8.4http://www.linear.com/product/LT1510
2-Channel function gen/AWG external trigger setup - Page 1
Forum section: electronics / beginners

author: armandine2
author_rank: Frequent Contributor
timestamp: June 12, 2023, 10:35:38 am
content: w2aew#281: Bipolar Transistor Switching Time Measurementfrom 11:501st channel to generate a pulse from zero volts to a positive level, that I could adjust right here, and, then I’m also using that to trigger the second channel, which is creating a negative pulse That negative pulse is going into the add input on the back of the generator and adding into this waveform and I have it set up so that it’s delayed by this pulse width.So, I’m essentially creating this one pulse that’s triggering a second pulse that’s delayed that creates the negative pulse on channel two where I can adjust the negative drive level that’s occurring after the input pulseSo, by adding those two together I can essentially create this waveform that goes from zero to an adjustable positive to an adjustable negative and back to zero.w2aew's description seems ok to me - followable - but the screenshots, at least for channel 2, I don't understand.any thoughts?

author: Old Printer
author_rank: Frequent Contributor
timestamp: June 12, 2023, 01:08:26 pm
content: Have you asked Alan (w2aew)? He is quite approachable and very helpful.
2 Channel power supply  - Page 1
Forum section: electronics / beginners

author: DzAnej
author_rank: Contributor
timestamp: February 19, 2017, 11:54:50 am
content: Hi there,I'm working on a 2 Channel power supply using a transformer with 2X 25V/5A outputs. Next, i would need a supply (5V) for the regulation circuit (microcontroller(s)).Now, because i have 2 channels - how do I measure the voltages on the both outputs without clamping all the grounds together? For now I was testing using an instrumentional amplifier but with that I had to put the grounds together to make it work...For now I thought one way of doing it - Each channel would use its own supply to power the measurment circuit and then send it digitally to the main controller via an optocoupler - that way the 3 grounds (2 channels and main controller) are isolated.Is there a better way than this and how is this done in commercial multiple channel power supplies?

author: Brumby
author_rank: Unknown
timestamp: February 19, 2017, 12:03:53 pm
content: Two meters.These days, they are cheap enough.

author: Cliff Matthews
author_rank: Unknown
timestamp: February 19, 2017, 02:04:48 pm
content: Yes, they are cheap:http://www.ebay.com/itm/DC-100V-10A-Voltmeter-Ammeter-Blue-Red-LED-Dual-Digital-Volt-Amp-Meter-Gauge/162237038985

author: DzAnej
author_rank: Contributor
timestamp: February 19, 2017, 02:40:24 pm
content: Well, I forgot to mention, the supply will be programmable... There will be one display showing preset and actual voltage/current...

author: Cliff Matthews
author_rank: Unknown
timestamp: February 19, 2017, 07:02:13 pm
content: You mentioned "one display" so the MCU running that can run the side powering it. As for having the other side isolated and yet controlled by the same MCU, that'll likely require high-speed optical circuitry (shifting out and latching DAC data along with getting ADC data back to the MCU on the other side). That may be a stretch for this beginners forum.*Edit - Skip the separate 5v supply, since 7805's can do it fine (and plan for 12 or 24v to run beefy output relays too).Q - Have you considered a slaved, display-less MCU to efficiently run the other side?(You'd still need to opto-exchange command, display and relay data, but the throughput rate wouldn't be so high.
2 layer PCB ground and VCC plane question - Page 1
Forum section: electronics / beginners

author: djex81
author_rank: Newbie
timestamp: January 17, 2021, 06:01:59 pm
content: Hello all. I'm new here and new to PCB design. I wasn't sure if I should post this here or in the PCB forum... any ways. Through my research I can not seem to find a clear answer to my question. I'm designing a few PCBs for a MIDI controller which will contain a mix of either push buttons (cherry mx switches), LEDs, or rotary encoders. All ICs and power will be on a separate main board. These PCBs will be the the ones the user will interact with and will connect to the main board via ribbon cable.So my question is this. I'm building these on a 2 layer board. Are there any issues with making the top layer the ground plane and the bottom layer VCC and routing all signal traces on the VCC plane? I read that splitting up a ground plane with traces take away the benefits that a solid ground pour gives. Is this the same for a VCC plane? Some say you should not run traces on a VCC plane and some say you can. Some say on a two layer board having both a ground and VCC plane is not a good idea and that there should only be a ground plane ... However in my case having both planes helps keep the PCB small as I only need to route signal traces.I've included my schematic and top and bottom PCB images below. Any guidance or tips would be appreciated.

author: Terry Bites
author_rank: Super Contributor
timestamp: January 17, 2021, 06:38:41 pm
content: With a switch matrix power planes are probably unnecessary unless your scanning them in the Megahertz.So all's well, go etch. Don't connect mounting holes to ground unless you really need to..... am I seeing Vutrax??

author: djex81
author_rank: Newbie
timestamp: January 17, 2021, 06:53:07 pm
content: Quote from: Terry Bites on January 17, 2021, 06:38:41 pmI wasn't sure if mounting holes should be connected to ground or not. Thank you for point that out. Yeah I'm using a Teensy 3.6 and it will be scanning in the MHz range. The clock speed runs at 180 MHz which is probably too fast to scan at and so I'm probably going to have to slow it down some.And no not Vutrax. I'm using EasyEDA right now since I'm going to use JLCPCB to print the boards.Quick question though. When would I ever want to connect the mounting holes to ground? I'm assuring only when the boards need to connect to chassis ground?
2 LEDs w/reset - Page 1
Forum section: electronics / beginners

author: gilbenl
author_rank: Regular Contributor
timestamp: May 28, 2017, 12:45:49 am
content: I want to make a light that alternates between two colors, A and B, on power cycle:(on>A>off/on>B>off/on>A...)But when power remains off for a few seconds, say 10, it reverts to A on next power cycle:(on>A>off 10s/on>A>off/on>B).Needs to beverysmall. Explain like I'm five.

author: SebG
author_rank: Regular Contributor
timestamp: May 28, 2017, 07:37:09 am
content: You can try something like in the image. You can get a small inverting D-Flip Flop like 74LVC1G80GV,125. That would work with a 5V power supply but if you want higher voltages or even AC you might need to build a D-Flipflop from transistors.The circuit tries to keep the D-flipflop powered during the sort power off cycle with the capacitor but the signal to the clock is isolated from the capacitor using a diode. So the clock will pulse high when power is applied and then fall low when disconnected and if the flipflop remains powered by the capacitor and the main switch is pressed again it will toggle the output again. On initial power up the clock pulse can toggle the output so you can add a small filter (debounce) to delay the signal so you get consistent power up value.One light is gated by a P-MOS and is on when the output is low. And the other is gated by a N-MOS and is on when the output is High.The two pull down resistors should be high value like 10k or so.

author: gilbenl
author_rank: Regular Contributor
timestamp: May 28, 2017, 04:04:16 pm
content: Thank you-Looks like a promising starting point. I have some CD4013BD ICs somewhere I can dig out and test. It will be a 12V-13.6V circuit (car), but I suppose I could use a zener for the IC.

author: SebG
author_rank: Regular Contributor
timestamp: May 28, 2017, 11:21:42 pm
content: if you use a zener diode for the IC the output will not drive the PMOS gate to a high enough voltage to turn it off. (ie the Vgs will not be low enough since Vsource will be 12V) You need to use an open collector driver with a pull up resistor to 12V driving the PMOS. So when the output of the IC is high the PMOS gate is pulled up by the resistor to 12V turning it off and when the IC output is Low the open collector driver pulls it low turning it on.

author: Zero999
author_rank: Super Contributor
timestamp: May 28, 2017, 11:28:52 pm
content: If the LEDs only need 10mA or so then there's no need for the MOSFETs. Connect the LEDs and series resistors to the 'Q' output, with one to +V and the other to 0V.
2 lithium cells to  12v? - Page 1
Forum section: electronics / beginners

author: k.neo
author_rank: Newbie
timestamp: December 26, 2023, 10:19:22 pm
content: Hello.I have a 12v project I am working on.I wish to use 2 lithium cells to power it, either series or parallel.Is there a circuit that can manage the step up and charging of the cells?18650 or 21700.

author: Peabody
author_rank: Super Contributor
timestamp: December 26, 2023, 10:32:46 pm
content: The one linked below is for two 18650s in parallel. The fine print at the bottom says the 12V version will do 1.2A. One negative for this module is that it doesn't have any way to turn it off except removing the batteries. I think that's a pretty big negative. But it has protection built in, as well as a load sharing circuit which lets you charge the batteries and power the load at the same time.https://www.ebay.com/itm/204252590625

author: BeBuLamar
author_rank: Super Contributor
timestamp: December 26, 2023, 11:36:58 pm
content: Why don't you just use 3 cells and without the converter?

author: k.neo
author_rank: Newbie
timestamp: December 27, 2023, 01:39:18 am
content: Using 3 cells could be a valid point.Would need a bms charging circuit for protection, wouldnt I?Any suggestions?The end goal is to power a DC ballast for a 4w to 10w uv tube. I am not sure what wattage to go for yet. The longer the tube the bigger the ligth fixture will be.The ebay suggestion is interesting, maybe a switch could be spliced in.

author: BeBuLamar
author_rank: Super Contributor
timestamp: December 27, 2023, 11:29:10 am
content: I would use 3 cells and the charger with BMS would be a separate device.

author: Zero999
author_rank: Super Contributor
timestamp: December 27, 2023, 02:16:18 pm
content: What wavelength does the UV tube output? If it's a black light i.e. 350nm to 390nm. then go for LED, which is much more efficient in this wavelength range.

author: Peabody
author_rank: Super Contributor
timestamp: December 27, 2023, 03:21:57 pm
content: What's your charging source voltage?

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 27, 2023, 10:39:53 pm
content: i use this 3 cells cheap circuit in my latest project... just supply with 12V mains adapter source on its output pin, when blackout, its on batteries. its mini UPS... fwiw..https://www.aliexpress.com/item/1005004858806346.htmlhttps://www.ebay.com.my/itm/384308219625https://shopee.com.my/3S-20A-Li-ion-Lithium-18650-Charger-PCB-BMS-Protection-Board-12.6V-Cell-64x20x3.4mm-Module-i.32805005.23637159505

author: p.larner
author_rank: Frequent Contributor
timestamp: December 30, 2023, 09:01:35 pm
content: Just a word of warning,not all of the el cheapo ebay bms units have working low voltage cutoff,i built a 6s battery using one of those for my prc-320 radio,then left it on rx to see how long a charge lasted,it killed 3 groups of 18650 cells.
2 Motor USB Stepper Controller without Messing around - Page 1
Forum section: electronics / beginners

author: Orestecom
author_rank: Newbie
timestamp: March 31, 2019, 09:32:19 am
content: Hi everyoneAnyone available for a Paid Project. We Need to control 2 stepper motors (under one AMP each) via USB connected to a Windows PC with our custom application. Polulu and trinamic Offer only 1 or 3 plus axis. And 3+exceeds the budget of 100dollar per Controller.Not an Option ist putting several components together such als 1 arduino 2 Stepper 1 shield 3... 5...2... And each has to be programmed seperately.A Trinamic custom solution would be my FavouriteYou may send me a Line to oreste@oreste.com Have a good One

author: ebclr
author_rank: Super Contributor
timestamp: April 01, 2019, 10:28:12 am
content: This can be easily done with arduino somehing like thishttps://pt.aliexpress.com/item/Placa-Controladora-3-GRBL-Laser-Eixo-Stepper-Motor-Driver-USB-Placa-de-Grava-o-A-Laser/32961197563.html?spm=a2g03.search0104.3.52.3b1f6abbQo89uq&transAbTest=ae803_3&ws_ab_test=searchweb0_0%2Csearchweb201602_8_10065_10068_10547_319_10059_10884_317_10548_10887_10696_321_322_10084_453_10083_454_10103_10618_10307_537_536%2Csearchweb201603_16%2CppcSwitch_0&algo_pvid=842fffc0-1623-4596-818f-a63c270447d8&algo_expid=842fffc0-1623-4596-818f-a63c270447d8-7
2 phase Full Wave Voltage Multiplier for maximum voltage? - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: May 06, 2020, 07:13:54 am
content: I am building a tube amp and need more B+ from it, it draws about 700mA from the B+ and I need 1kV and the power transformer outputs 400-0-400VACI can't use just a 2 phase rectifier since I intend to use it in class B2, (for experimental purposes) and need about -300V bias (why I need such high bias? long story short: I'm using a cf to drive the output, and because of it, it reduces the -300V to about -100V. also, I have the plate at 8V, I could connect it to ground, but then I couldn't get it into class 2, I'm sure)anyway, I was wondering, can I use a 'Full Wave Voltage Multiplier' circuit to get 2 supplies double the voltage?or is there maybe a better circuit for this?I couldmaybeuse a voltage doubler but I doubt it could handle 700mA.
2 pin output ZVS vs 3 pin output? - Page 1
Forum section: electronics / beginners

author: owin
author_rank: Newbie
timestamp: August 24, 2023, 08:36:07 am
content: Hello, what's the practical difference between 2 pin output ZVS and a 3 pin output?Generally, 3 pin output is being used as a flyback driver and 2 pin as an induction heater driver. Why would you use a 3 pin over a 2 pin?Does the 3 pin receive feedback to synchronise the frequency to the harmonics of the coil?Thankyou.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 24, 2023, 10:26:03 pm
content: Look, you're approaching this with WAY too much formality.You're lucky if the manufacturer even knows what the board does, or how it works. Frankly they put some parts on a board, and it seems to sell. Whether there's design intent behind that (or just copycat, or a wholly random walk at all), let alone any kind of support or service infrastructure -- irrelevant. It's just a board from Ali (or Amazon, or eBay, or..). It's nothing more and nothing less than the circuit you see in front of you.If I had toguess, assuming that the circuits are the traditional kind, for the traditional meaning of what that is (which, realize, is quite a stretch given the vast space of possible circuits that might be described using these few vague terms -- but given their popularity, this interpretation is still most likely to be correct); I would guess that the three-terminal one -- because it has one inductor rather than two -- is made for centertapped windings ONLY, while the other one can use either arrangement (just leave the CT unconnected).If it means you got (or are about to get) scammed because you bought something you have no idea how to use, or that means you can figure out some use (maybe not the original desired or intended function, even), whatever -- so it is.Tim

author: owin
author_rank: Newbie
timestamp: August 25, 2023, 05:16:33 am
content: Yes the 3 pin requires a centre tapped primary, but the question is why? what does a centre tapped primary achieve that isn't done by a straight coil? Is it purely just a design of the oscillator that has no bearing on the final output?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 25, 2023, 06:24:26 am
content: It has one less component.
2 pole, 2 way  switch question - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 04, 2015, 12:28:02 pm
content: I have 2 server power supplies, 50V at 73 amps each. Outputs are isolated from ground. I want to put them in a cabinet and have a high capacity switch to change their outputs from parallel to series. I want to use a 2 pole, 2 way switch for this, but suitable amperage ones are hard to find. The schematic I will work from is attached. Can I use this Ebay sourced switch, or even cheaper, use two double pole 100 amp mains isolation switches bought separately (for a lot less) with their toggles bridged together and mounted on a common DIN rail, with (and I think I would need to do this...) one mounted upside down??http://www.ebay.ie/itm/CHANGEOVER-SWITCH-GENERATOR-TRANSFER-125-AMP-1-SINGLE-PHASE-DIN-RAIL-COSDIN-/281692272367?hash=item41962af6ef:g:0HwAAOSw9N1Vk9GRThanks!

author: Ian.M
author_rank: Super Contributor
timestamp: November 04, 2015, 12:51:56 pm
content: No. Its contacts almost certainly aren't designed to clear a 50VDC high current arc.You need a switch rated for at least 120V 100A DC (120V because it has to clear the arc when the PSUs are in series)Try googling: 100A DC knife switch DPDT

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 04, 2015, 01:03:49 pm
content: Ahh, OK, thanks, but would it be OK if no live switching was done? I cannot foresee a time when i would want to go from series to parallel or vice versa with the supply feeding a load.

author: Ian.M
author_rank: Super Contributor
timestamp: November 04, 2015, 01:40:12 pm
content: Not OK, but it can carry the current and withstand the voltage. If you are lucky, it might even survive operating under moderate load a few times. However its an electrical fire waiting to happen unless you can rig an interlocked cover that shuts down the PSUs before anyone can access the switch.

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 04, 2015, 01:58:46 pm
content: OK, got you, thanks for the warning, I'll probably look for a knife switch, but only I will be operating it, and all the big knife switches seem to be in China, much appreciated Ian!Actually they do an enclosed one, I could put a microswitch on the cover and have it run a relay on the input side, I have some BIG relays... Cheers.