hybridfree/eevblog-posts huggingface dataset:
MFOS Keyboard Controller Sample&Hold - Page 1
Forum section: electronics / projects

author: nedhayward
author_rank: Newbie
timestamp: August 08, 2020, 11:56:47 am
content: HiI've spent a bit of time recently trying to breadboard a 1v/oct keyboard controller circuit from Music From Outer Space, and have run into a bit of trouble! Part of the circuit is a sample and hold, the idea being that when a key is pressed, a short trigger pulse momentarily turns on a jfet which charges a capacitor up to what ever voltage is present at the source, and this is then buffered by an op amp, thus holding the source voltage. the problem I've been having is that instead of holding a constant voltage, the S&H part of the circuit causes the voltage to ramp up to V+. I've tried to trace this back to the root of the problem and I've discovered that if I connect the 10nF cap from the non-inverting of the buffer to ground, without connecting it to anything else, the output still ramps up like it was before, rather than staying at a constant voltage like i would expect. I just don't understand where it's being charged from! - Hopefully I'm explaining myself well enough, if not hopefully the attachment will help!I've tried replacing the JFETs to no avail, so I'm thinking that, because the ramping still happens with the sampling capacitor/buffer disconnected from the rest of the circuit, it must be a problem either with the cap or the opamp? I've tried with TL074 and TL084 op amps and had the same problem both times, I know the circuit recommends LF444, however I haven't be able to source any yet! If anyone can offer some insight as to why I'm having this problem I'd be very grateful! Been tearing my hair out for a few days now...The circuit I'm referencing, and explanation, can be found herehttp://musicfromouterspace.com/index.php?CATPARTNO=PCBMFSNGBUSSKBRD&PROJARG=SINGLEBUSSKEYBOARD2007%2FSINGLEBUSSKEYBOARD2007.php&MAINTAB=SYNTHDIY&SONGID=NONE&VPW=1252&VPH=500Thanks!Ned
MHV or SHV ? - Page 1
Forum section: electronics / projects

author: veedub565
author_rank: Frequent Contributor
timestamp: March 22, 2019, 06:33:58 pm
content: Hi, just looking to see if someone can help confirm which type of connectors these are (attached). They are fitted to a 3kv PSU, I think they are MHV, although I'm told they are SHV.SHV would protrude more though, so I'm fairly sure they are MHV, I just want to check.Could of course still be BNC, but I did try one and it wouldn't go on. Unless it is a very tight fit.

author: doktor pyta
author_rank: Frequent Contributor
timestamp: March 22, 2019, 09:16:22 pm
content: a photo showing side view of the plug would be nice.

author: aamirchef135
author_rank: Newbie
timestamp: March 22, 2019, 09:39:05 pm
content: NOTE: This message has been deleted by the forum moderator Simon for being against the forum rules and/or at the discretion of the moderator as being in the best interests of the forum community and the nature of the thread.If you believe this to be in error, please contact the moderator involved.An optional additional explanation is:

author: veedub565
author_rank: Frequent Contributor
timestamp: March 23, 2019, 07:10:38 am
content: Agreed, a side view would be helpful. Unfortunately I don't have one, and I don't have the kit with me at the moment.

author: Jonathan9192
author_rank: Newbie
timestamp: September 20, 2019, 12:33:45 am
content: Hi there,this is MHV.SHV has (wrt BNC and MHV) the inner connector pieces exchanged between male and female connectors.Cheers,Jonathan
Mic XLR with detection - Page 1
Forum section: electronics / projects

author: NMP
author_rank: Contributor
timestamp: November 16, 2019, 05:31:47 pm
content: HiI Need to detect if a microphone is present.Just know 3.5mm jack with detection, been searching but did not find a 3 pin xlr female with this.Does anyone knows a 3 or 4pin xlr female with detection?Regards!

author: DaJMasta
author_rank: Super Contributor
timestamp: November 16, 2019, 05:39:07 pm
content: 3.5mm jack detection is very easy, because they just have a 4th contact that is displaced when the plug is inserted - XLR connectors don't have this as part of their basic design. If you want mic sensing, you're probably going to have to do it in circuitry, and while that's not too tough if you have phantom power on (you can just look for current consumption), it's going to be tricky for other mics.If you want detection on such a jack..... I'd just use a TRS jack with the 4th contact for detection, then use TRS to XLR adapters.

author: coppice
author_rank: Super Contributor
timestamp: November 16, 2019, 06:00:26 pm
content: The Neutrik connectors which combine XLR and 1/4" jack into one thing detect what is inserted.

author: jhpadjustable
author_rank: Frequent Contributor
timestamp: November 16, 2019, 06:04:12 pm
content: https://www.neutrik.com/en/product/nc3fbv2-sw

author: NMP
author_rank: Contributor
timestamp: November 18, 2019, 12:06:20 am
content: This Neutrik is perfect.Thank you!
Mica washer insulator - how os called that rubber thing? - Page 1
Forum section: electronics / projects

author: zaoka
author_rank: Frequent Contributor
timestamp: September 25, 2013, 08:11:35 pm
content: What is the name if that grey rubber thing used instead of mica washers for transistors?I need that in bigger size, is it available from Digikey?http://www.westfloridacomponents.com/mm5/graphics/00000001/TR98-0008-SC.jpg

author: WarSim
author_rank: Frequent Contributor
timestamp: September 25, 2013, 08:22:33 pm
content: They go by many names like sil-pad. That are in digikey by various manufacturer in the same area as mica. Thermal management, I believe. They come in different isolation voltages, and thermal resistances, sizes, thicknesses, compounds,Non sure which package you are looking for given the picture with no dimensions.

author: David_AVD
author_rank: Super Contributor
timestamp: September 25, 2013, 08:58:41 pm
content: I'm guessing by the relative size of the hole the picture is of a TO-220 one? The larger package is called a TOP-3 sometimes.

author: wraper
author_rank: Unknown
timestamp: September 25, 2013, 09:00:12 pm
content: Thermal pad, sil-pad, SMICA, thermally conductive pad, silicone rubber, etc... They often are under different names in different catalogs.

author: Experimentonomen
author_rank: Regular Contributor
timestamp: September 25, 2013, 09:04:11 pm
content: There are three main kinds of these insulators, the worst one is the Sil-pad, the next best one is the mica sheet, and the best one is the Aluminum oxide one which is also the most expensive one.

author: Monkeh
author_rank: Super Contributor
timestamp: September 25, 2013, 09:11:04 pm
content: "Best", "worst", try different for different applications.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: September 25, 2013, 09:37:38 pm
content: Hi,One of the leading manufacturers in this area is Bergquist.http://www.bergquistcompany.com/thermal_materials/gap-pad.htmThey are the owners of the trademark 'sil-pad'Jay_Diddy_B

author: G7PSK
author_rank: Super Contributor
timestamp: September 26, 2013, 07:43:16 am
content: You can get sheets of sil pad type material from E bay.http://www.ebay.co.uk/itm/Blue-100mmx100mmx2mm-GPU-CPU-Heatsink-Cooling-Thermal-Conductive-Silicone-Pad-/190704123549?pt=US_Thermal_Compounds_Supplies&hash=item2c66d9fe9d

author: wraper
author_rank: Unknown
timestamp: September 26, 2013, 01:47:44 pm
content: Quote from: G7PSK on September 26, 2013, 07:43:16 amThis is a bit different stuff. It isn't meant for insulation. Just thermal interface for BGA and similar.

author: ElektroQuark
author_rank: Unknown
timestamp: September 26, 2013, 03:50:36 pm
content: And it is 2mm thick!
Micro-D sub connector selection - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: December 24, 2020, 09:18:42 am
content: Hi,I want to select a robust shock and dust resistance 51 pin and 100 pin Micro-D sub connector, for the 51 pin version I have selected DCCM51SCBRPN, I want to know what mating options I can choose? I have hard time finding the mating connectors for them, is there any recommended part number for mating connector? Do some members in here have used Cinch connectors?Do you recommend some other manufacturers? which part numbers?
micro ribbon cable "tap" - Page 1
Forum section: electronics / projects

author: sarepairman2
author_rank: Frequent Contributor
timestamp: December 29, 2015, 02:18:37 am
content: Does anyone sell a connector which can be used to "tap" a ribbon cable?i.e. there is a ribbon cable going from one component to the main PCB on a cell phone. Let's say you wanna put a logic analyzer on it. Does anyone make pass through connectors that can be tapped off to a sniffer PCB?For those tiny ribbon cables found in cell phones and such.

author: Ian.M
author_rank: Super Contributor
timestamp: December 29, 2015, 05:26:01 am
content: They are nearly all device specific, and you'd need a breakout board with two sockets on it + a compatible extender cable, so even if you find a solution for one product, its unlikely to be much help for anything else.
PCB trace antenna radiation pattern - Page 1
Forum section: electronics / projects

author: okw
author_rank: Frequent Contributor
timestamp: April 04, 2023, 04:07:54 pm
content: I'm designing a PCB trace antenna, 433.92MHz. I'm new to this and wonder, where does the antenna "start" radiating? I am trying to design the perfect length 1/4 wave for 433.92MHz (172.7233465 mm), so it would be helpful to know where the length should be calculated from. Is it where I "open" the ground plane (restrict copper pour)? Or also somewhere during the trace leading up to the antenna (depending on how wide the track and/or the spacing to the ground plane maybe)?For the calculation, I am adding all the segments (straight lines on TOP layer, 3 segment S-shape on BOT layer). Should I add the 25 pcs 1.6mm through the PCB for every hole too?Any hints on via stitching around the trace and/or the square?

author: Benta
author_rank: Super Contributor
timestamp: April 04, 2023, 08:01:27 pm
content: Impossible to say, you'll need to add a shortening factor for the FR-4 dielectric as well.Best thind to do is measure it with a 1 GHz network analyzer, but very few people have such a thing.

author: okw
author_rank: Frequent Contributor
timestamp: April 04, 2023, 08:08:01 pm
content: ThanksI have a 2.7GHz VNA, so I'll experiment. Thought I would try to take the best possible academic/theoretical approach before start testing and experimenting. One guy told me he used to make the antenna too long, experimenting by cutting the trace until desired resultsI might do that. He also encouraged me to drop the 'N' shape and instead make it into 'W' shapes (offset the bottom drill holes by 1/2 the distance of the top ones).

author: mayor
author_rank: Regular Contributor
timestamp: April 05, 2023, 11:27:43 am
content: You might find this useful :https://www.ti.com/lit/an/swra496a/swra496a.pdfhttps://www.ti.com/lit/an/swra416/swra416.pdf?ts=1680618495190See antennae 4 and 10. You do need to add the via lengths to the total length.I use a similar antenna for 915 MHz, and place footprints for a pi network, rather than cut up the antenna. Since you have a VNA, you'll be able to measure what passives are required for the filter.
Micro-USB Connection Question: are these parts equivalent? - Page 1
Forum section: electronics / projects

author: colorado.rob
author_rank: Frequent Contributor
timestamp: July 15, 2017, 02:20:25 am
content: I have looked at theFCI 10118194-0001LFandMolex 105017-0001micro-USB connectors and, other than price, these seem to be equivalent parts. The pad and hole layouts look identical enough that an FCI part can be used with theKicad footprint for the Molex part.Are they truly interchangeable on the board? I'd like to use the Molex footprint with the FCI part.Is there any reason these two would not be interchangeable on the BOM with that footprint?Is there anything that justifies the added cost of the Molex part?

author: janekm
author_rank: Unknown
timestamp: July 15, 2017, 02:35:06 am
content: They are designed to be drop-in replacements. I believe they were actually specified by the USB-IF at some point but I can't find the reference now other than for the terrible SMD-only version.Molex has a little more brand recognition in the US so that's probably why they can charge more on digikey, but both are excellent brands for these kinds of connectors. You can also get much cheaper Chinese-made versions which are also fine for most applications.
Micro USB Data and Power Delivery - Page 1
Forum section: electronics / projects

author: crazymach
author_rank: Newbie
timestamp: May 08, 2018, 04:22:06 am
content: I am currently working a side project which involves USB data delivery and phone charging.Is there a solution that supplies 500mA while data is sent to Phone on the same D+ and D- lines?I have been looking through different forums for power delivery and I have noted that most of the charging circuits used a fixed voltage divider to help the phone recognize a power supply.This is a problem for me because I would like to also supply data on those same lines.Or is there some sort of high speed mux that selects the voltage divider voltage or data lines from the processor?I created a image that shows what I'm trying to find.Note: Everything is sharing same GND line. Just got lazy drawing it in.

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 08, 2018, 04:47:51 am
content: What you're looking for is to implement a USB CDP. It apparently can be as simple as connecting the data lines to a comparator and GPIO through resistors and adding a bit of code to send the right signal, can't comment more since I never tried it.

author: ajb
author_rank: Super Contributor
timestamp: May 08, 2018, 04:51:16 am
content: There are three basic behavior profiles for USB 2.0 ports (actually part of a separate battery charging spec from USB-IF), the one you want is a "Charging Downstream Port":Quotefromhttps://www.maximintegrated.com/en/app-notes/index.mvp/id/4803,which explains some of the different behaviors (naturally featuring Maxim products).There are ICs that integrate power switch, overcurrent protection, CDP logic, and data line switching all in one package, for instance TI's TPS2540 family.There is also USB Power Delivery, which is more complex, but I don't think that's common on USB 2.0 systems.
Micro USB sockets - Page 1
Forum section: electronics / projects

author: keef46
author_rank: Contributor
timestamp: June 06, 2022, 02:59:21 pm
content: Is anyone aware of a right angle trough-hole Micro USB socket, or an SMT one that is not impossible to hand solder!

author: robert.rozee
author_rank: Frequent Contributor
timestamp: June 06, 2022, 03:19:55 pm
content: this may be your simplest option in small numbers:https://www.ebay.com/itm/295010802997"10Pcs MICRO USB to DIP Adapter 5Pin Female Connector PCB Converter Board"approx nz$4 for 10.cheers,rob :-)

author: keef46
author_rank: Contributor
timestamp: June 07, 2022, 10:16:04 am
content: Gone with these! (i only need power....)https://www.ebay.co.uk/itm/362624814166

author: JPortici
author_rank: Super Contributor
timestamp: June 07, 2022, 12:24:03 pm
content: Quote from: keef46 on June 06, 2022, 02:59:21 pmmost of them! the secret is to extend the pads for at least 0.5-1 mm respect the suggested land pattern
Microamp constant current sink - Page 1
Forum section: electronics / projects

author: jkrbasu
author_rank: Contributor
timestamp: December 19, 2017, 04:49:15 am
content: Hi EEVBloggers-I'm trying to put together a constant current sink circuit for discharging small Lithium-Ion coin cells. I need to be able to sink from about 200 uA to 12 mA. My first thought was to use some voltage regulators like the LM317 or the LP2951. Unfortunately for the LM317 as the battery discharges from 4.2V to 3V the sink current doesn't remain constant at low currents (see attached picture2.png).I've attached the circuit (picture1.png)- I'm measuring voltage across the 10 Ohm resistor to measure current. R2 is a 256 step digital potentiometer to set sink current. In Multisim it seems like I shouldn't have a problem getting down to ~200 uA, but in practice, I don't get the same currents when the voltage source is at 3V or 4.2V (I'm using a power supply to simulate a battery). In the attached graph of current vs. pot value, I can only maintain stable current between 3 and 4.2V at currents > 1mA.I tried the LP2951 in the same circuit but got even worse results (picture3.png). What gives? I thought the 2951 was a low dropout regulator, and so should have no problem with the low output voltage?Does anyone have a suggestion for a better voltage regulator or circuit design for sinking such low currents?Thanks!

author: David Hess
author_rank: Super Contributor
timestamp: December 19, 2017, 05:30:02 am
content: The LM317 and similar regulators have a quiescent current of from 1 to 10 milliamps which flows to the output pin so this is the minimum current they can produce. AnLM334 current referencewill do what you want or acurrent sink like thiscan be used.

author: jkrbasu
author_rank: Contributor
timestamp: December 19, 2017, 07:22:57 am
content: Ah, right- forgot about the quiescent current.Thanks for the recommendation!

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 19, 2017, 04:45:04 pm
content: To add to what David said, in addition to a classic, op-amp/mos-based current sink, you could also use the REF200 from TI for the low currents, which would allow you to sink 50 µA, 100 µA, 200 µA, 300 µA, or 400 µA very accurately without any trimming needed.

author: David Hess
author_rank: Super Contributor
timestamp: December 19, 2017, 07:35:49 pm
content: A single transistor and LED temperature compensated current sink could be used but it would require a separate supply for biasing. A suitable JFET like a 2N5457 with a single resistor would work.
Microbyte Electronics Australia- What happened to them? - Page 1
Forum section: electronics / projects

author: bulkystapler
author_rank: Newbie
timestamp: January 29, 2018, 01:14:12 am
content: Hi,I am requiring information/support for a PIC development board manufactured (as a kit) by Microbyte Electronics. Their website seems to be defunct.Can anybody give me any information relating to an alternative source of support material for the products that they made.\?Thanks in advance,David

author: imidis
author_rank: Frequent Contributor
timestamp: January 29, 2018, 02:15:55 am
content: Can't seem to find much on them. Looks like they closed 2009Basically just a chip breakout?This might helphttps://web.archive.org/web/20081011114911/http://www.microbyte.com.au:80/page/shop/info_page/a/infopage_id/e/4
Microcap ,stepping resistor values to check NTC linearization - Page 1
Forum section: electronics / projects

author: DIEGOTREX
author_rank: Newbie
timestamp: June 16, 2024, 12:01:31 pm
content: HiI am using Microcap 12 at basic level ,since years.I ask your help to have Microcap showing me (exactly as normally done with a spreadsheet) the value of a voltage divider ,following the steps of the NTC table itself, having on the x-axis the temperature values and on the y-axys a scale suitable to represent the resulting voltage.Best I was able to do was having the divider resulting values on y-axis, but on x-axis I got equally spaced resistor values instead of temperature steps .I didi it in DC simulation inserting a list of values in Seep->Range(please ,see attachments).Having 0,1,2,3 on x-axis would be an improvement .Still better would be a list of temperature value6 (-30 , -25 ).No problem having it in Excel ,but in Microcap i could add non linear elements.Thanks for your helpDiego

author: Terry Bites
author_rank: Super Contributor
timestamp: June 17, 2024, 07:04:18 pm
content: Microcap has a fairly big selection of ntc thermistors.Pick one. Search "NTC" in the component finder. Or tweak the spice modelThe best method is to use comma separated lists of T an R in X and Y . Vendors do supply these for more "up market" thermistors. eg YSIOrPut T in the X and the thermistor eqn in the Y.I've been down this rabit hole a few times. Thermsitors are very tricky to linearise over anything but a small tange of T.See my "not quite to be taken as the whole story" calculator. Also seewww.edn.com/linearize-thermistors-with-new-formula/Beta is poorly controlled and it varies with temperature so its very hard to simulate the true circuit behaviour.It becomes obvious that pretty much any series resistor of the same order of magnitude as Rt25' will work.Only slope and intercept will be affected. Trying to get precise linearisation is a wasted effort.As they say, you can't gild a turd...

author: DIEGOTREX
author_rank: Newbie
timestamp: June 17, 2024, 10:08:58 pm
content: Thanks Terry Bites.You did a good work for what I understand,I should follow it step by step to appreciate it completely , if I am not completely wrong ,one of the points in the article is " In NTC linearization a compromise is unavoidable ,so better to choose the best range to apply it in the best way possible ,keeping in account the error".Please , just for practicing in Microcap, can you attach the screenshot of the window(s) where the lists of T and R values must be pasted in X and Y ?Thanks for your help

author: Terry Bites
author_rank: Super Contributor
timestamp: June 18, 2024, 05:50:22 am
content: Like this:

author: DIEGOTREX
author_rank: Newbie
timestamp: June 24, 2024, 06:19:41 am
content: Thank you so much for the attached pic showing circuit and components name.What i need it is a bit different:In your example you are using an NTC ,and temperature it is the parameter in the list.Is this method valid even in case i use a normal resistor ,or more generally a component for which I have a list of values?Thanks
Microcap, a very powerfull circuit simulator is now free. No HASP key needed. - Page 1
Forum section: electronics / projects

author: rbola35618
author_rank: Frequent Contributor
timestamp: October 03, 2019, 02:17:38 am
content: Just found out that Microcap which is a very powerfull simulator is now free. It looks like the owner is retiring and decided to make it free to the engineering community. This indeed is a very powerfull simulator. This simulator sold for about 5000 dollars is not in the public domain. Thank your sir for making it free to the engineering community.News:Effective 7/4/2019, Spectrum Software is closed. Micro-Cap is now free.Technical support will be available for at least 90 days via email at Support.You can download the latest versions of Micro-Cap here: DownloadYou can choose either the executable program or the entire installation CD for MC10, MC11, and MC12. If you have an earlier version, download and use MC12. These new versions do not require the security key, so they make Micro-Cap free to the entire engineering community.Thank you for the honor and privilege of serving you for the last 39 years.Spectrum Softwarehttp://www.spectrum-soft.com/index.shtm

author: Phoenix
author_rank: Frequent Contributor
timestamp: October 04, 2019, 02:46:02 am
content: Good news, but this is already being covered herehttps://www.eevblog.com/forum/projects/microcap-12-is-free-(as-in-beer)-now/
Microchip Current Sensing Fundementals App Note - Page 1
Forum section: electronics / projects

author: Rhythmtech
author_rank: Regular Contributor
timestamp: October 05, 2010, 01:57:58 pm
content: Microchip AN1332I found this app note to be an easy good overview of current sensing. Just thought I would throw it out there for anyone else who might like it.

author: Time
author_rank: Frequent Contributor
timestamp: October 05, 2010, 03:42:35 pm
content: I had to brush up on my common mode voltages before I was able to absorb a whole lot.http://dxxy.yangtzeu.edu.cn/gcjc/upimg/soft/xxck/zl/gmdy.pdf(Skip to practical examples of common mode voltages if you don't like mathematical gymnastics)Thanks for the post though, this is convenient because I am having to design a some what unique battery charger right now.

author: Rhythmtech
author_rank: Regular Contributor
timestamp: October 05, 2010, 04:37:54 pm
content: No problem, glad you liked it. Are you going to share the battery charger specifics eventually?

author: Time
author_rank: Frequent Contributor
timestamp: October 05, 2010, 09:51:51 pm
content: Quote from: Rhythmtech on October 05, 2010, 04:37:54 pmI think so - once I know for sure what needs to be done with the project.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 06, 2010, 02:45:51 am
content: I'm surprised they didn't include the opamp and transistor balance current mirror...

author: Rhythmtech
author_rank: Regular Contributor
timestamp: October 07, 2010, 06:33:51 pm
content: Quote from: NiHaoMike on October 06, 2010, 02:45:51 amFeel free to submit a reference design or app note for it. Seems like the right place...

author: TopherTheME
author_rank: Regular Contributor
timestamp: October 17, 2010, 09:35:15 pm
content: I wish they had more info about low side current sense design. Linear has a much more thorough app note about current sense me thinks.http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1009,C1077,D12479
microchip display interface - Page 1
Forum section: electronics / projects

author: iamjohn
author_rank: Newbie
timestamp: April 24, 2014, 11:04:00 am
content: I was wondering if anyone knows how to interface a display like the one shown at:https://forums.adafruit.com/viewtopic.php?f=25&t=52167&start=30using one of the microchip parts and the best part (smallest, least expensive) to use for something like that. I only need 3 extra I/O pins after whatever is needed to connect to that display. I've seen these displays on ebay or I could just use one of the ones from adafruit which would save me a lot of work trying to connect to it since I don't have to put it into something small like that guy did.

author: dannyf
author_rank: Super Contributor
timestamp: April 24, 2014, 11:07:22 am
content: If you provide a datasheet to the display, people can help you better.

author: mariush
author_rank: Super Contributor
timestamp: April 24, 2014, 11:22:27 am
content: Display is standard oled with SPI or i2c communication so you can talk to them with any microcontroller that's powerful enough.Most PIC controllers will have hardware spi or i2c. The OLED display that guy used is on sale on Adafruit as the following comments say, so if you go on the sale page, you'll find there documentation for it (how to talk to it using your PIC). If not, it's enough to go on Digikey, mouser, newark and search for a similar oled display with the same pinout and the datasheet for those displays will contain the instructions and everything you need to know.

author: iamjohn
author_rank: Newbie
timestamp: April 24, 2014, 11:38:39 am
content: Thanks mariush! You gave me enough information to get me going, it doesn't seem like it will be so difficult after all.
Microchip ICD2 to breadboard cable fabrication - Page 1
Forum section: electronics / projects

author: djsb
author_rank: Super Contributor
timestamp: November 13, 2010, 02:15:30 pm
content: I want to make an ICD2 to breadboard cable. I would like confirmation on what RJ plug to use on the ICD2 end. Is it an RJ11 or RJ12 plug thats needed? Also what cable can I use for this purpose. The cable only needs 5 wires. Can anyone recommend any suitable pins (individual if possible-Don't want to use a header) that will fit into a breadboards holes. I will obviously be using heat shrink to cover any solder joints and the flying wires on the cable. Thanks for any help.P.S I will be using this with the PIC16F877. I'm assuming I don't need a dedicated header board for the ICD2 to be used with this chip. If using a 16F628 is a header board needed?

author: johnmx
author_rank: Frequent Contributor
timestamp: November 13, 2010, 02:49:27 pm
content: You need a RJ12 plug.In case of a breadboard I simply use the cable itself. Since the wires are flexible I simply tin the tips. Don’t forget to label each wire to prevent mistakes.
MicroChip MCP3901 Eval Board Issues - Page 1
Forum section: electronics / projects

author: Kryten 2X4B
author_rank: Contributor
timestamp: March 09, 2016, 09:47:51 am
content: A while ago Chris Gammell was talking about the Microchip MCP3901/MCP39XX A/D conveters. As I'm wanting upgrade one of my products I thought I'd have a look at the MCP39XX chips and they appear to have many of the features I require and they are 20% of the cost the Maxim part I'm currently using. So I decided buy an evaluation board to test the MCP3901 part for my application, got one from Digikey and from that point things started to go down hill.I downloaded the data viewing app for Windows from the MicroChip website, and right out of the box the board would not communicate with the Windows app (fail). Then I downloaded the PDF manual from the MicroChip website, as you do when the thing doesn't work and it turned out that manual was for the original version of the board not my Rev 5 (fail). Then other work got in the way and I put the project aside for about six months. Back in January this year I had another look at the board and tried re-flashing the microcontroller, made no difference. Also tried running the PC app under XP, Win 7, as well as Win 10 and it didn't work under any of them, so I was starting to suspect the board.So I opened a Case on the MicroChip Support website on 25 Jan 2016, left a comment 15 Feb 2016 that I hadn't had a reply, yesterday 8 Mar 2016 started a conversation with a MicroChip guy. He pointed me in the right direction as far as getting new code to re-flash the eval board which is now working. Soon I should be getting the correct documentation for the the Rev 5 board, which as far as know hasn't been publically available on the MicroChip website but the Rev 5 board has been available for a few years.Hopefully MicroChip will update their website so other people won't have the issues I've had.
Microchip Step Down Regulator MCP16301 Help needed - Page 1
Forum section: electronics / projects

author: andybarrett1
author_rank: Regular Contributor
timestamp: June 03, 2016, 08:46:01 am
content: Hi and thank you for readingWe are using a MCP16301 as a 5v Regulator from a linear regulated LM7824 feed.The circuit is a direct lift from the Microchip Datasheet. (5v @ 600mA)However we are finding after a few hours use the MCP16301 is going totally short circuit forcing the full 24v across our PIC.All the MCP16301 is sourcing is a PIC and three Leds.Although the DataSheet does not mention Current Limiting on the supply to the MCP16301. Would this help ?BRAndy

author: PChi
author_rank: Frequent Contributor
timestamp: June 03, 2016, 02:43:34 pm
content: My guess is that adding a current limit wouldn't help. The MCP16301 claims to have an NMOS switch current limit. If the inductor isn't saturating at that current limit I don't know why the part is failing. What does the waveform of the SW pin look like?

author: andybarrett1
author_rank: Regular Contributor
timestamp: June 03, 2016, 07:11:55 pm
content: HiI can have a look on MondayOut of office at momentBRAndy

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 03, 2016, 07:33:11 pm
content: I use this part a lot, but not sure I'd trust such a small package for outputs as high as 600mA, regardless of what the datasheet says.Is it failing during operation, or at power-up ? Problems with the latter can be caused by voltage spikes caused by inductance of input cabling combined with the low ESR of input caps.If the former then how hot does it run ? Maybe an issue with heating altering the inductor's characteristics & causing saturation ?

author: andybarrett1
author_rank: Regular Contributor
timestamp: June 04, 2016, 06:40:02 am
content: HiThe Datasheet says 5v@600mA .... I am using a small Pic and 3 LEDs... So no load at all really .. Less than 100mAUnit is warm ... It has a mains T/X but not essesive ....Caps are low ESR Panasonic !BRandy
Microchip Technology 3D TouchPad - Page 1
Forum section: electronics / projects

author: Zucca
author_rank: Unknown
timestamp: April 21, 2015, 12:51:31 pm
content: http://www.microchip.com/DevelopmentTools/ProductDetails.aspx?PartNO=DM160225Probably is not a news for most of you, but I did´t know that. Not sure if in the everyday life would be useful... Price is about $100.Meh...
Microchip XC8-Getting started - Page 1
Forum section: electronics / projects

author: djsb
author_rank: Super Contributor
timestamp: October 20, 2012, 03:10:17 pm
content: I'm trying to light an LED on portb (say B0) of a 16f819 using XC8. I've had a look in the header file to try to find a directive to set bit 0 of port b as an output and then turn it on and then off after a short delay. I usually use CCS C (which is easy) but would like to use XC8 as well. I had a look at some of the tutorials on Gooligumhttp://www.gooligum.com.au/tutorials.htmlbut they use a different (and simpler) chip. Has anyone used XC8 with any of the mid range devices? If so could you give me a quick example listing I can try and then I can take it from there.Thanks.David.PS Where can I find a list of config bit keyword for this chip that I can use in the #pragma directive to set the config fuses?There is nothing in the header file.

author: krish2487
author_rank: Frequent Contributor
timestamp: October 20, 2012, 04:23:13 pm
content: XC8 is actually repackaged Hitech C compiler with support for PIC18 devices.pretty much any of the tutorials shown on that wonderful site will workout-of-the-box for XC8just include the file xc.h in your main.cAs a matter of fact, i have just migrated from hitech to XC8 on linux and it took me less than a couple of hours to familiarize myself with XC8the manual is a great help.FWIWthe code for what you intend to do isCode:TRISB=0b00000000;while(1){PORTB=0b00000001;__delay_ms(250);PORTB=0b00000000__delay_ms(250);}Look under the "docs" folder in XC8 installation directory.there are two html files by name "pic_chipinfo.hml" and "pic18_chipinfo.html"they contain a list of the devices supported and if you click on a device link, it gives a detailed explanation on how to use the #pragma directive for the config bits.:-)

author: djsb
author_rank: Super Contributor
timestamp: October 20, 2012, 04:53:09 pm
content: Thank you.That's exactly what I needed.David.

author: krish2487
author_rank: Frequent Contributor
timestamp: October 21, 2012, 05:56:28 am
content: You are welcome.:-)
Microchip's Beloved MCP2221 USB-I2C Datasheet Has Mistake?! - Page 1
Forum section: electronics / projects

author: MicroBiggerThanMM
author_rank: Contributor
timestamp: January 17, 2021, 05:37:42 am
content: Edit: No it doesn't. Murphy caused the PCB to be wrong. That being said, it's annoying that things can't be routed this simply.Hello all,The MCP2221 is a nifty alternative to FTDI with UART's, DAC's, ADC's, GPIO's, and I2C for $2.But, the datasheet says V_DD is the power input and V_USB is the output of the internal LDO.Okay, counterintuitive, but I designed the circuit, tossed my $100 of components on the thing, and when I measure it, it turns out it was counter-counterintuitive.Applying 5V to VDD results in 5V on VUSB, and 5V on VUSB results in 3.3V on VDD.Did Microchip mess up in figure 1-2? I feel like they should have been more explicit about using the internal LDO to get a 3.3V supply.Maybe I just designed everything really late at night.

author: ataradov
author_rank: Super Contributor
timestamp: January 17, 2021, 07:26:37 am
content: You are doing something wrong. The datasheet mentions in multiple places that V_DD is an input and V_USB is an output of the regulator.Electrical characteristics mention:V_DD 3.0 - 5.5 VV_USB 3.0 - 3.6 VIt is possible that something is broken after you applied 5 V to V_USB. Absolute maximum ratings mention "Voltage on V USB pin with respect to V SS ... –0.3V to +4.0V"

author: MicroBiggerThanMM
author_rank: Contributor
timestamp: January 17, 2021, 05:15:53 pm
content: Doh! The PCB was switched around
Microcontroller Advice - Page 1
Forum section: electronics / projects

author: PsychoMaster
author_rank: Regular Contributor
timestamp: March 17, 2015, 08:07:08 pm
content: Hello AllI really only wanted to learn stuff that is straight forward (uses pots that you can feel working and none of this SMT stuff) only I saw one of them transistor testers based around a Mega 328p and was blown away by it .I can't miss out on that stuff can I?I know nothing about m/c's and would like to be pointed where to start .What manufacturer and what programming language is used? .Are libraries easy to use and easy to acquire? I do a bit of Python code for being lazy on the computer and wondered if this can carry across.I never thought I'd be interested until I saw the possibilities .Thanks

author: daybyter
author_rank: Frequent Contributor
timestamp: March 17, 2015, 08:13:28 pm
content: Arduinos are cheap and there are lots of tutorials for them.http://arduino.cc/en/Tutorial/HomePagehttp://www.ladyada.net/learn/arduino/
Microcontroller based battery protection (will this work) - Page 1
Forum section: electronics / projects

author: lutkeveld
author_rank: Regular Contributor
timestamp: July 27, 2017, 01:45:19 pm
content: I recently came up with this idea of a fully programmable ATMEGA328P based battery protection board with balancing.It reads out the voltage of all the cells and bleeds off any imbalances. When the lowest voltage cell goes below a certain treshold it disconnects the load and puts the microcontroller in a very low power shutdown mode. The 3V3 is regulated by a LM2936 (low Iq).The resistors on the left are needed to get the voltage of the cells down to the ADC range of the uC. They would be 100k+ ohms to prevent quiescent current.Do you guys see any problem? Would this work if I try to build it?

author: mikerj
author_rank: Super Contributor
timestamp: July 27, 2017, 02:24:06 pm
content: How do you think the 3.3v logic output from the micro is going to be able to switch Q1-Q5 on when the source voltages will all be greater than 3.3v?

author: Fungus
author_rank: Super Contributor
timestamp: July 27, 2017, 03:01:37 pm
content: How will you bleed (eg) BT4 without bleeding BT5, BT6 and BT1 as well.

author: Fungus
author_rank: Super Contributor
timestamp: July 27, 2017, 03:04:09 pm
content: Quote from: mikerj on July 27, 2017, 02:24:06 pmEasy! Q5 can be switched on when Q6 is switched on. Q4 can be switched on when Q5+Q6 are switched on.

author: Zero999
author_rank: Super Contributor
timestamp: July 27, 2017, 06:12:44 pm
content: Quote from: Fungus on July 27, 2017, 03:04:09 pmTrue and that could be useful if the voltages are measured on the drains of the transistors.

author: mikerj
author_rank: Super Contributor
timestamp: July 28, 2017, 06:42:48 pm
content: Quote from: Fungus on July 27, 2017, 03:04:09 pmTrue, but not terribly useful for cell balancing...

author: brainwash
author_rank: Frequent Contributor
timestamp: July 31, 2017, 12:10:56 am
content: Another issue is that at 100k the ADC current might not meet the minimum specs . Assuming you want to go with this design, the ADC switching needs a lot more settling time than usual.
microcontroller based frequency synthesizer - Page 1
Forum section: electronics / projects

author: nobizzoh
author_rank: Newbie
timestamp: January 30, 2014, 11:43:15 am
content: Hi guys, I am designing a microcontroller based frequency synthesizer as my final year project and am stuck somehow. Please help me out with a circuit diagram incorporating atmega32 microcotroller with a dds, all interfaced with an lcd and keyboard.

author: daqq
author_rank: Super Contributor
timestamp: January 30, 2014, 11:48:51 am
content: QuoteWhat exactly do you mean by "designing"? Based on the question it seems like a very nonconventional way of designing something. For inspiration though, google gave me this within a few seconds:http://www.qsl.net/pa3ckr/bascom%20and%20avr/ad9951/index.html

author: Psi
author_rank: Super Contributor
timestamp: January 30, 2014, 12:05:28 pm
content: If it's your final year project you should be able to draw up the initial circuit yourself.Asking for help in one problem area is perfectly fine but it's not ok to ask us to do the circuit design for your finial year project.Unless your course is only on software, and the hardware part you're doing on your own. Then i guess its ok.

author: nobizzoh
author_rank: Newbie
timestamp: January 30, 2014, 12:12:20 pm
content: Thanks Daqq...I appreciate the help.I have an initial circuit but it was a bit more complicated and my supervisor wanted me to make it a bit basic, thats why I sought help

author: dannyf
author_rank: Super Contributor
timestamp: January 30, 2014, 12:17:10 pm
content: QuoteNice story.Anyone attempting to help you is actually doing you a disfavor.What you need is to learn, not to copy-and-paste other people's circuits.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 30, 2014, 12:21:29 pm
content: Quote from: nobizzoh on January 30, 2014, 12:12:20 pmPosting your initial circuit would help a lot and will prove that you actually did some work yourself before asking.
Microcontroller Crystal Overheated? - Page 1
Forum section: electronics / projects

author: Glenn0010
author_rank: Regular Contributor
timestamp: May 20, 2018, 07:56:11 am
content: I had a crystal physically close the a Micro controller which I had to unsolder. I used hot air to remove the micro controller and soldered a new one.I had a bunch of intermittent fault where most 90% of the time the micro controller would not boot and I could not communicate to it via serial. After a bunch of debugging I could not find what was wrong and deiced to replace the crystal as a last resort.To my surprise after replacing the crystal everything worked normally. Could the crystal have overheated whie using the hot air to unsolder the microcontroller?

author: Rerouter
author_rank: Super Contributor
timestamp: May 20, 2018, 08:10:31 am
content: You would have to refer to the datasheet, as it will tell you exactly how long its rated for X temperature for its soldering profile.There are a few ways it could cause problems, from flux leakage under the crystal (A little leakage can kill low power oscillators). to melting the base or some internal support inside the crystal,You could have also had a dry joint with the pad under the crystal being heavily oxidised, I've seen weirder multiple times,

author: Glenn0010
author_rank: Regular Contributor
timestamp: May 20, 2018, 09:17:22 am
content: The datasheet does nit have any info regarding soldering temps which is wierd.The flux residue like yoi said could be an issue. When I removed the old crystal there was some residue which I cleaned off. Did not know that could be an issue

author: jpanhalt
author_rank: Super Contributor
timestamp: May 20, 2018, 09:34:49 am
content: Crumpled aluminum foil placed loosely around parts you don't want to get hot works wonders.As for detecting the cause, don't you check whether the oscillator is running before proceeding in the program?
microcontroller gnd pin  - Page 1
Forum section: electronics / projects

author: electros6
author_rank: Regular Contributor
timestamp: October 18, 2013, 02:44:05 pm
content: I have checked with multimeter that the two GND pins in the micro-controller was around 1 ohms . Please somebody tell1) what is the need of two GND or more GND pins if they are shorted internally2) The resistance between the GND pin is around 1 ohms , why3) whether this pin can be used to provide GND to other side of the circuit

author: Kjelt
author_rank: Super Contributor
timestamp: October 18, 2013, 03:10:28 pm
content: Can be lots of reasons depending on the micro controller:-analogue ground and digital ground for seperating the supplies-bonding wire can handle lets say 100mA and the microcontroller has to be able to sink on all GPIO pins a total of 200mA (fill in any value you like)-layout of the silicon, two groundwires easier layout (for instance power for the core and power for peripherals) or lower impedance.and lots more,two is not much, there are plenty of chips (like fpga's) that have more then ten ground connections and different power pins.

author: c4757p
author_rank: Super Contributor
timestamp: October 18, 2013, 03:34:00 pm
content: 1 ohm is not a short. They quite simply probably decided they needed lower than 1 ohm to ground. You need a lower ground resistance to help avoidground bounce.

author: tszaboo
author_rank: Super Contributor
timestamp: October 18, 2013, 04:13:56 pm
content: Each and every GND pin must be connected to the ground on the PCB with a low impedance path for proper operation. Same goes for VCC. And you need separate decoupling. And it is not a jumper. Unless you design a time bomb.For high speed digital circuits, it is necessary (ground bouncing and stuff) to have a GND and VCC every 8-10-20 digital output, just to have proper slew rates.

author: Neilm
author_rank: Super Contributor
timestamp: October 18, 2013, 04:29:22 pm
content: Quote from: NANDBlog on October 18, 2013, 04:13:56 pmIt would also be required to provide low impedance returns for EMI purposes.
Microcontroller must deliberately set pin high -- glitch prevention - Page 1
Forum section: electronics / projects

author: ezalys
author_rank: Frequent Contributor
timestamp: September 23, 2020, 02:34:29 am
content: Suppose I have a microcontroller that controls some pyrotechnics (specious example). When I turn the microcontroller on, I want to ensure that the microcontroller doesn't blip the pin that sets the firework ablaze. Is the pin state guaranteed during startup? Will an external pulldown do? What are some ways to design in this guarantee?An overkill solution might be a timer outputting a square wave, followed by a crystal BPF, rectifier, and comparator, as it's basically impossible for the microcontroller to come up in such a way that the thing is configured to emit a square wave of a particular frequency. Any other ideas?

author: Pawelr98
author_rank: Regular Contributor
timestamp: September 23, 2020, 03:08:27 am
content: CD4017 and output on 9.Would require 9 pulses to set things off.Continuous output won't increase the counter state.Or if the pulse is short then just use an RC network with a long enough delay.Test the particular uC for behaviour of output.

author: ataradov
author_rank: Super Contributor
timestamp: September 23, 2020, 03:13:56 am
content: That really depends on the MCU type, but generally behavior on startup is predictable. But often the default state is a weak pull-up. But in any case, if your control signal is active high, then just place a pull-down resistor and be done with it.

author: ejeffrey
author_rank: Super Contributor
timestamp: September 23, 2020, 03:48:01 am
content: Most microcontroller start up with most IO pins in a high impedance state. However during power up when the supply voltage is less than the minimum operation voltage that may not be guaranteed. A fairly stiff pull down may help here as the intermediate states are likely to be fairly high impedance. It would be better to have an inhibit circuit that is enforced until the power is good and the micro core has started. For instance you could do this with a power supply sequencer. The power for the pyrotechnics only turns on X milliseconds after the mcu regulator power good is active.

author: BrianHG
author_rank: Super Contributor
timestamp: September 23, 2020, 04:07:30 am
content: Use a 2 input and gate with 1 input having a 1uf cap to GND and a 100k series resistor to a uC output as power-good, or enable, or call it your lock/key output.Share that 1 signal between multiple and and gates inputs for each channel you want to drive a protected output.Add a backwards diode to VCC on that and gate input to rapid discharge the cap on loss of system power making sure a brownout relocks the and gates..For each channel, drive the other input of each and gate with an IO.A bottom end 74HC08 will do and you should not see a pulse to high during powerup.You will need to drive that series 100k 'un-lock' for a good 2 seconds prior using any of the protected channels.