hybridfree/eevblog-posts huggingface dataset:
Counters as a simple way to change modes? [LED with passives] - Page 1
Forum section: electronics / projects

author: kalel
author_rank: Frequent Contributor
timestamp: June 13, 2017, 08:01:35 pm
content: I'm wondering if a counter IC would facilitate a simplest solution to changing "modes" on something like a small LED light, or whether there could be some unforeseen (or quite foreseen for experienced people) issues with that.For example, let's imagine that the counter IC can drive an LED directly (some can), or otherwise just amplify the output.Would it be reasonable as a simplest solution to using a momentary/push button (I hope I got the name right, it goes LOW when not pressed and HIGH only upon being pressed) to switch "modes" (e.g. light intensity and on/off) with something like this:Power Supply > Counter IC > Resistor > LEDWhere for each output on the Counter IC a different set of resistors can be added in-line with the LED, to provide different light outputs. Likely a decade counter in this case.For an "OFF" mode, the output would simply not be connected to the LED.If we have less modes than the counter has outputs, one output could be connected to the "RESET" pin of the IC.Basically, is something like this a reasonable solution for the simplest circuit (least components), or would it simply not work, or is there perhaps a yet simpler solution?

author: Kleinstein
author_rank: Super Contributor
timestamp: June 13, 2017, 08:33:43 pm
content: Mechanical switches usually show some ringing when operated. This can make the counter to count up be way more than 1 - up to the point of making a kind of dice - thus a random jump. So it would usually take some measures to avoid ringing. This could be something like a SPDT switch operating between a H and L level with a small capacitor for buffering.A second point to watch is that many counters have a limit on how slow the input signal is allowed to change.

author: Someone
author_rank: Super Contributor
timestamp: June 14, 2017, 01:44:49 am
content: Depends what the output needs to be, there were some dirty ideas here:https://www.eevblog.com/forum/projects/discrete-logic-design-vs-a-super-cheap-micro/msg624674/#msg624674

author: tszaboo
author_rank: Super Contributor
timestamp: June 14, 2017, 03:11:06 pm
content: Quote from: Kleinstein on June 13, 2017, 08:33:43 pmIf you design for low cost, adding an RC filter for the button and using schmitt trigger input solves this problem 99% of the time.The only issue I'm seeing is the currents. See, for a decade counter, 1 input is high 9 is low. So most of the current will flow out of the IC through the resistor, do a 180 degree turn, flow back into trough the resistors into the IC, ground. So you need an open collector output, or add series diodes.
Couple of PSU decisions - Page 1
Forum section: electronics / projects

author: fenclu
author_rank: Regular Contributor
timestamp: October 28, 2012, 04:35:30 pm
content: I'm almost at the end of designing my digital power supply based arround Arduino environment. I have some final decisions to make and I thought you might help me out1. Is it a good idea to make this PSU double channel (it would still be a single transformer). Could I connect two channels to get dual rails?2. I had a couple of ideas of how to power this thing : transformer inside the case, external plug pack and a 5.5mm jack on the back of the PSU, or both (transformer + DC jack)3. How do I lay out the front panel? I would have a 16x2 LCD, two encoders, double USB 5v output, binding posts (2 or 4) and a power switch. I wanted to get encoders with push buttons to either toggle between current and voltage setting or turn on the output. I think I won't be able to avoid using tact switches on the front panel. What do you think?4. What's the best way to cool this thing? I would have one or two LT3080s, 7805 for the USB outputs (all in TO220s) and a 7805 for the uC in a D2-PAK. The thing is that I only have a small heatsink (12x5x1.5cm) and a 120x120mm fan.If I think of any other questions I'll post them.Thanks

author: penfold
author_rank: Frequent Contributor
timestamp: October 28, 2012, 07:35:27 pm
content: First point, you can only connect multiple outputs together if they are sourced from separate isolated supplies, for example separate windings on a transformer or multiple plug packsIf you have a transformer inside the case and a DC jack without having some kind of load sharing between them you'd have a power supply with the weight of a transformer and the extra bulk having the plug pack. If i were you I would keep to just having the transformer in the case, keeps it an all in one solution.As far as cooling you need to do some quick calculations on power dissipation, pick your maximum input (to the regulator) voltage, the minimum output voltage and maximum current to get the worst case scenario power level. You can probably ignore the D2-PAK 7805 unless you're excessively loading it.If you come up with some really unrealistic power dissipation needing a massive heatsink you might want to start considering a bit of diversity and wondering what sort of practical loads you will be drawing from it

author: fenclu
author_rank: Regular Contributor
timestamp: October 28, 2012, 10:09:59 pm
content: On the second thought this transformer + DC jack is stupidDespite the fact that I couldn't make two channels into dual rails, is it a good idea to make this double channel (it's obviously a good idea, the question is, will it work?)
Coupling an NTC to a LiPo battery - Page 1
Forum section: electronics / projects

author: ebastler
author_rank: Super Contributor
timestamp: November 29, 2020, 06:02:37 pm
content: I want to mount a flat, single-cell LiPo battery (approx. 300 mAh, 3 to 4 mm thick) on a small PCB, together with its charger chip (STNS01) and a micro USB jack. The whole assembly is meant to stay as low-profile as possible.I am wondering where to best place the NTC resistor which the charger uses to sense the battery temperature. I can't put it in direct contact with one of the flat sides of the battery, since that woud add unwanted height. Is it an accepted practice to have a large thermal pad (copper area) below the battery, then place the NTC right next to the battery, with its GND connection on that thermal pad?There are no other components on the back side of the PCB opposite the battery, so no active heat sources. But that side of the PCB will be open to the environment (room temperature), so there will be some heat losses.Thanks for your opinions, or better ideas on how to place the NTC!

author: Siwastaja
author_rank: Super Contributor
timestamp: November 29, 2020, 06:54:35 pm
content: The NTC can't protect the battery from blowing up with excessively high dT/dt anyway, that's up to the passive safety of the cell (and preventing excessive currents by sensing current / e-fusing / fusing), so it's there to react to slow changes, like the cell heating up while running at allowed currents for a long time (tens of minutes) at high ambient temperature, or inside a blanket.It's also there to limit/prevent charging at cold temperatures.So perfect coupling to the cell is not important. Sometimes just ambient temperature is sensed, but if you can get it to couple to the cell even a bit, it's always good. I would be perfectly happy with a copper pour delivering some heat from the cell to a surface mount NTC placed right next to the cell.

author: trobbins
author_rank: Frequent Contributor
timestamp: November 30, 2020, 10:45:48 am
content: Further to that, it can be worthwhile thinking of the NTC as a thermocouple, and utilising the broad experience built up on thermocouples.Reduce the thermal mass as much as possible of your sensor and the thermal conductive path between the casing of the cell and the NTC itself (ie. use the smallest sensor practical, and if the sensor has a mounting lug then consider if the lug is really needed in your particular situation). Reduce the thermal resistance as much as possible between the two. Increase the thermal resistance from the NTC to ambient - the caveat is not to increase the thermal resistance from the cell to ambient - so there is a compromise going on as to what thermal insulation is used and where - and that includes the leads going to the NTC (ie. use the smallest practical gauge wire). Sense the hottest region of the cell.
coupling resistor on power conditioner output - Page 1
Forum section: electronics / projects

author: gkmaia
author_rank: Frequent Contributor
timestamp: August 23, 2020, 09:57:47 am
content: I got a Furman power conditioner that has a faulty resistor. R7 on the left of the schematics on the output block has burned to death... so cannot read it.Could anyone give me a hand to understand what a resistor on that circuit design does and it's likely value?

author: oschonrock
author_rank: Regular Contributor
timestamp: August 23, 2020, 02:40:53 pm
content: What is being connected at Tab10/Tab6? Is that the output of the conditioner?Where did you get this schematic from? Are you sure all of D9/D10/D11/D12 are the correct way around?

author: gkmaia
author_rank: Frequent Contributor
timestamp: August 23, 2020, 09:10:43 pm
content: You were right. D12 was inverted. Fixed it and uploaded a new one to my previous post.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 23, 2020, 11:01:34 pm
content: Appears to be just a bleeder for the overshoot dampening circuit. A 330k, 1W resistor will work well with fairly low power dissipation, just beware it will take some time to discharge the cap. Add a blue LED in series as a visual indication of voltage.

author: gkmaia
author_rank: Frequent Contributor
timestamp: August 23, 2020, 11:19:39 pm
content: thanks for the reply. So this basically allows to extra overshot voltage to be feed to C7 maintaining the voltage somewhat more stable?So this means, it will still work with no resistor there. It will just not smooth the AC as well as it could?

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 24, 2020, 12:21:21 am
content: Quote from: gkmaia on August 23, 2020, 11:19:39 pmCorrect, also the capacitor will stay charged for a very long time so beware the next time you work on it.

author: gkmaia
author_rank: Frequent Contributor
timestamp: August 24, 2020, 12:45:26 am
content: thanks, that makes sense.I could get hold on two other working board and pulled the resistor out.It seems 3 wattsOn my all my 3 HP multimeters both working ones read more than 20Mohm (beyond the range) while the code I wouold say either 15k or 10k... not sure.I am confuse....

author: perieanuo
author_rank: Frequent Contributor
timestamp: August 24, 2020, 09:35:16 am
content: 10kbut for 220w is too low wattage those 3wyou have 120vac in nz?in 120VAC case, 10k may be the one, you have less than 2w dissipated powersorry, I don't know by heart voltages in your country, but for 10k I guess it's 120volts

author: gkmaia
author_rank: Frequent Contributor
timestamp: August 24, 2020, 09:44:14 am
content: We have 240v here in NZ.
CP2102 maximum DTR / RTS / BREAK speed ? - Page 1
Forum section: electronics / projects

author: Jaunedeau
author_rank: Regular Contributor
timestamp: April 27, 2015, 08:06:11 pm
content: Hi,I am making my own pic programming software (only as a learning exercise). I bought an usb to ttl adapter. Unfortunately, I did not know that CLP2104 could be used as real gpio and ordered a CLP2102 (CLP2104 is ordered from china but will take 3-4 weeks to get there).I made some tests using the CLP2102 as a com port using RXTX from java, or "directly" in C#, and if I toggle DTR and rts from 0 to 1 and then 1 to 0 (4 bits changes), I can reach the speed of 14 iterations per second. By optimizing things (toggling data only if needed) I can reach about 20 bit per second. The same code run 100+ times faster if I user my desktop's motherboard's uart.Trying so send break is even slower than toggling rts/dtrCan the CP2102 be switched faster by using the USBXpress and/or C code ? And the CP2104 (using GPIO mode) ?Thanks you,John.

author: moffy
author_rank: Super Contributor
timestamp: April 28, 2015, 01:32:34 am
content: I assume "20 bit per second" is 20Hz. I use a little USB to rs232 TTL board using the CP2102 and it works fine at 115200 baud, not toggling RTS etc. though. But that implies that the handshaking if enabled would work well into the multi kHz range. The speed problem is on the PC/Programming side.

author: moffy
author_rank: Super Contributor
timestamp: April 28, 2015, 02:47:06 am
content: Look at:http://community.silabs.com/t5/8-bit-MCU/cp2103-GPIO/td-p/74485

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 28, 2015, 07:04:31 am
content: Have you tried plugging the USB-RS232 into a USB 2.0 (or 3.0) hub instead of directly into a PC? I once discovered that due to some strange quirk, it greatly accelerated bit banging.
CP2102N USB to Serial Converter - Page 1
Forum section: electronics / projects

author: alaa2003
author_rank: Newbie
timestamp: December 04, 2023, 09:06:06 pm
content: Helloanybody tests this ttl converter with version A02 chip, which supplier you advice.I prefer the item should has two led for tx,rx indicator & programmablehttps://www.silabs.com/documents/public/data-sheets/cp2102n-datasheet.pdf

author: tooki
author_rank: Super Contributor
timestamp: December 04, 2023, 10:28:21 pm
content: What’s your question exactly?I’ve used that chip in several projects of my own, and it’s the chip used in most (all?) of the ESP32 dev boards sold by Espressif, so super widespread.The manual shows the TXT/RXT pins (RX/TX LED pins) on page 23.
CPLD & Cotex M3 on a miniPCIe card - Page 1
Forum section: electronics / projects

author: CM800
author_rank: Frequent Contributor
timestamp: October 16, 2016, 02:10:35 pm
content: I've been toying around today with the design of a small CPLD (MAX V) + a Cortex M3 ATSAM3A MCU on a miniPCIe card.Many of the nicer embedded computers, along with laptops, main motherboards have miniPCIe cards which have USB on them.Does anyone have any interest in such a little unit? I'd imagine most would rather just have a full FPGA on such a card.I suppose you could make a rather nice little CNC controller with such a setup maybe. I've already made a start, toying around in Eagle, think it's worth continuing and finishing off?Honestly I'm not all that sure what I was doing when I came up with it.

author: ebclr
author_rank: Super Contributor
timestamp: October 16, 2016, 04:02:21 pm
content: Take a lock on this datasheet if you want use pci-e communication you need high speed transceiversYou need to use SX familyhttps://www.altera.com/content/dam/altera-www/global/en_US/pdfs/literature/pt/cyclone-v-product-table.pdf

author: CM800
author_rank: Frequent Contributor
timestamp: October 16, 2016, 05:38:07 pm
content: Quote from: ebclr on October 16, 2016, 04:02:21 pmThanks for the link. I'm actually aware of that, however mini-PCIe also has USB on it which is pretty neat. I haven't got the experiance with PCI at all to even think of designing my own board - I have never used an FPGA, only CPLDs, and even then I'm well into learning. PCI is still black magic to me!

author: promacjoe
author_rank: Regular Contributor
timestamp: October 16, 2016, 06:17:21 pm
content: take a look at this.https://www.raspberrypi.org/blog/raspberry-pi-compute-module-new-product/a newer version is in the works that uses the raspberry Pi 3 chip. This board is made to be compatible with the laptop memory slot connector. That does not mean you can put it in your laptop memory slot. only that it uses the same connector. This seems to be a good choice for prototyping on the industrial scale, As well as the hobbyist. You can design a board that will interface with this connector, and not have all the unneeded connectors that is available on the raspberry pie.If you're looking to be compatible with Arduino Due, The M3 cortex is a good choice. But in comparison the Due is slow, and it is a discontinued product as far as the US Arduino web page goes. but there are other vendors that are selling Due compatible boards.Joe.

author: Scrts
author_rank: Frequent Contributor
timestamp: October 17, 2016, 11:40:57 am
content: Quote from: promacjoe on October 16, 2016, 06:17:21 pmWhat was this post about? Can I get to smoke the same?

author: CM800
author_rank: Frequent Contributor
timestamp: October 17, 2016, 11:46:49 am
content: Quote from: Scrts on October 17, 2016, 11:40:57 amThat's what I was thinking...
CPLD for PLL prescaller - Page 1
Forum section: electronics / projects

author: ealex
author_rank: Frequent Contributor
timestamp: March 05, 2014, 03:49:51 pm
content: HelloI've created a small verilog implementation for a PLL prescaler:The design contains:- 2 x 32 bit divide by N- 2 x inputs for Frequency and reference input- 2 x outputs for divided clock, the maximum Fout is Fin / 2- 2 x 32 bit shift registers for loading data, each with it's own input line- 1 x serial load clock- 1 x serial chip select, the shifted values are applied on the rising edge.The divide by N counters are clocked by the input signal that needs to be divided - i don't know if it's a good idea but it worked.The design fits on an LCMX02-256HC-6SG32I lattice CPLD, in 32 pin qfn package and it's specified to work up to 150Mhz.I've already tested it on a bigger device and it seems to work properly - the ratio between programmed value and input / output clocks, data loading and no glitches.Can this be used in real life ? the ideea is to create a generic sealed "pll block" that contains only the prescalers and phase comparator.For the phase comparator I intend to use a HC4046. Can it be implemented it in the CPLD as well ? It seems there is some room left.I'm quite curios of how many design "rules" I've overlooked as I'm trying to learn verilog by myself.I've attached the design files and reports.
CPLD Fun Board: homemade Arduino STM32 + CPLD low cost board... - Page 1
Forum section: electronics / projects

author: Just4Fun
author_rank: Contributor
timestamp: October 20, 2017, 12:29:21 pm
content: Hi all,I was curious to play with CPLD/FPGA stuff so I decided to make a board on my own...Here it is the result:and here a short video:video.It can be seen as two boards into one: a STM32F103 based Arduino (Maple Mini compatible; for a short story about the Maple Mini and the stm32duino seehere) and an Altera MAX II CPLD (EPM240T100 or EPM570T100) dev board to start playing with VHDL/Verilog, or just to try to use a CPLD with the Quartus II schematic editor.The basic idea is to have a STM32 Arduino to use as "stimulus generator" for the CPLD (e.g. I2C master) and an Altera MAX II CPLD on the same board. In this way is easier to set up a complete "test bench" for the CPLD "application" (e.g. your custom I2C interface).The cost should be about 5/6$ plus the PCB (I haven't done the precise BOM calculation yet...), buying the components "around". The "pluggable" LCD module and the optional stand-alone 50MHz oscillator aren't included in the cost count.All the details including the schematic and the PCB Gerber files can be foundhere.Cheers.

author: mubes
author_rank: Regular Contributor
timestamp: October 20, 2017, 04:28:23 pm
content: Nice! As a bonus you're likely to find that F103 has 128K rather than 64K of flash on it :-) i don't _need_ another project, but when I see cool stuff like this I always seem to end up with them...no idea how it happens

author: babysitter
author_rank: Frequent Contributor
timestamp: October 20, 2017, 07:01:30 pm
content: I like it - another guy from the hackerspace too. Keep us informed

author: Just4Fun
author_rank: Contributor
timestamp: October 20, 2017, 07:32:43 pm
content: Thanks guys!Quote from: mubes on October 20, 2017, 04:28:23 pmI'm so used to think at the F103C8 as an 128kB device that I forget to mention it....
CPU and LCD suggestion for a simple project.  - Page 1
Forum section: electronics / projects

author: Fixup
author_rank: Contributor
timestamp: March 15, 2016, 11:12:32 pm
content: Hi,I am planning to make a small project with a 5x5cm graphical LCD.Before I used microchip PIC (8bit) + character displays for most of my projects but now I'm considering NXP cortex M3 or some similar (LPCXpresso).What microcontroller and LCD would you recommend for a quite simple project that only needs to show some objects on the display?I am not so familiar with programming so I would like to keep it as simple as possible.

author: Rob Morley
author_rank: Newbie
timestamp: March 16, 2016, 12:24:15 am
content: If your trying to keep it simple any micro with a SPI bus and sufficient flash memory (> 32KB) will do. In the past I've used a Texas Instruments MSP430 and OLED display (160px x 128px), like the NHD-1.69-160128UGC3 on projects that required a small display.As far as the programming goes, all you need to do is set up the SPI bus and write start position, and the dimensions of the object to the screen controller and then write the bitmap data from flash to the graphics memory in the screen controller.I've attached a small program that converts bitmaps to RGB 16it, C array file, that should make to easy to display objects and run tests on your code. It's simple to use just find the bitmap you want to display in a folder, select it an then press the "Export to C" button and a c file is created in the same directory the bitmap is in. Use that C file to display the data.

author: Fixup
author_rank: Contributor
timestamp: March 16, 2016, 09:05:30 pm
content: Thx for the reply.I considered the MSP430. That microcontroller would definitely be a good choice.However in search for a suitable display i found on ebay a very cheap display and it lead me to Arduino.I have never used any Arduino so I now ordered a "UNO R3 2.0" ' inch TFT LCD PCB Adapter" and will give it a try. The hole package with a display costed £ 12,99. And when I checked I found that the displays can be bought separately at a very low price about (16€/10pcs).Here is a link to the displayhttp://www.inhaos.com/product_info.php?products_id=77I think this will do for my small project. Besides this display type will keep down the cost if this project turns out to be a good product and I end up selling it.

author: Cloud
author_rank: Regular Contributor
timestamp: March 16, 2016, 09:32:43 pm
content: Probably arduino would be the best, if you are not familiar with programming. Especially because you have many examples and libraries on the internet
CPU board Backplane design - Page 1
Forum section: electronics / projects

author: davorin
author_rank: Unknown
timestamp: July 13, 2014, 08:11:25 am
content: Following idea:Design a 19" 1 or 2HU rack where several linecards with onboard ARM CPU can be inserted.As the ARM i.MX6 CPU features onchip Ethernet and PCIe lane, the design goal is to use the PCIe for adding a real GBit ethernet interface and use the onchip ethernet port for connecting to the backplane to be able to talk to other boards and the master board.I've seen also Pericom does some PCIe briding chips, but I am not sure as PCIe would be useful in this case as a backplane instead of ethernet.Anybody did some similar designs where several CPU boards need to communicate with each other?

author: TiN
author_rank: Super Contributor
timestamp: July 13, 2014, 10:33:59 am
content: PCIe channel is way more demanding for design implementation, and it's also point-to-point interface.Meaning that your CPU is acting like a host, to which you connect target devices. I'm not familiar with i.MX series, but be sure to check if you can connect two ARM's together via their PCIe link, as that may require adding a bridge between.So Ethernet is for sure more versatile solution, and you can also use it to interface slower devices (which cannot cope with PCIe interface directly).

author: davorin
author_rank: Unknown
timestamp: July 13, 2014, 11:45:44 am
content: I think I will go anyway for ethernet bridging with a low-cost ethernet switch at the master card...That way not only I don't have to bother with PCIe bridging Linux drivers and applications,but also termination is much easier when a card is not plugged in...BTW: Has anyone seen 19" rack cases where line cards are fitted in horizontally?All models I've seen, like for example Schroff, are vertical mount only....

author: nctnico
author_rank: Super Contributor
timestamp: July 13, 2014, 05:48:25 pm
content: The cards are always mounted vertically for a good reason: natural convection!

author: davorin
author_rank: Unknown
timestamp: July 13, 2014, 05:51:19 pm
content: Ah yes....like Cisco is doing it *lol

author: Laertes
author_rank: Regular Contributor
timestamp: July 14, 2014, 04:58:08 pm
content: Another great advantage of using gigabit ethernet: If you want to test something on a logic level, just pull out a card, plug in a little adapter board and connect to a host computer - too easy. You could even build a little test port onto the backplane. Wanna inject a few commands? Write a tiny little python script. That could be a real pain in the ass with PCIe...If you do go for ethernet, take special care to design the backplane with EMI in mind. Lots of ethernet traces can be really nasty EMI sources.
CPU comparator design for a serial CPU. - Page 1
Forum section: electronics / projects

author: Jack70
author_rank: Newbie
timestamp: December 01, 2022, 12:28:06 pm
content: I'm working on a serial CPU, so every bit gets processed in serial bit for bit. Now I want to implement comparator, but the best solution I came up with was cascade of three D flip flop and one JK flip flop (used as flag), so if all bits are equal the JK would be set, if one bit is not equal it would never reach the JK flipflop. Maybe one of you has a better idea for this problem.If more info is needed, please ask.Edit/This is the idea, is for 4bits, comparator and cascade of flip flops behind it. Ignore the rest of the circuit, is just there for the simulation.

author: uwe__
author_rank: Newbie
timestamp: December 01, 2022, 02:21:11 pm
content: Will a design do with a reset input that resets the equal flag?

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 01, 2022, 02:26:18 pm
content: The flip-flip is set to 1 before comparing.Stream any number of bits, any difference will latch it to 0 until resetted.

author: Jack70
author_rank: Newbie
timestamp: December 03, 2022, 09:48:57 am
content: Quote from: uwe__ on December 01, 2022, 02:21:11 pmThat depends on which instruction uses the comparator, I'm planning to use it for a conditional jump instruction, after the jump the flag will be rest.Quote from: DavidAlfa on December 01, 2022, 02:26:18 pmThat will work, if any bit is not equal the whole number isn't equal, thx mate! Sometimes it's that easy but you just don't see it yourself.
CR2032 open circuit voltage - Page 1
Forum section: electronics / projects

author: edavid
author_rank: Super Contributor
timestamp: November 20, 2015, 05:16:12 pm
content: Is it possible to judge CR2032 cell capacity based on open circuit voltage?The datasheets I've looked at are extremely vague, listing open circuit voltage ranges like 3.0-3.5V. However, this contradicts my experience, where new fresh cells always measure 3.30-3.35V, and old used cells are down around 3.0V.Is it really possible to have a full capacity cell with an open circuit voltage of 3.0V?What's a good acceptance test for CR2032s?

author: IanB
author_rank: Super Contributor
timestamp: November 20, 2015, 05:20:27 pm
content: Quote from: edavid on November 20, 2015, 05:16:12 pmI'm going to guess reputable brand and fresh package date?

author: ralphd
author_rank: Frequent Contributor
timestamp: November 20, 2015, 10:07:02 pm
content: I test cheal CR2032s with a blue LED. Below 2.8V under load is usually bad.

author: Artlav
author_rank: Frequent Contributor
timestamp: November 20, 2015, 10:11:05 pm
content: I remember seeing a paper that described how to determine SoC of various cell types by open circuit voltage.It involved giving the cell a few days of rest, measuring with a high impedance meter and doing some very chemistry-dependent math.So i guess it's possible, but it's not anything straightforward.

author: nukie
author_rank: Frequent Contributor
timestamp: November 22, 2015, 01:43:19 pm
content: When it's really cold.

author: edavid
author_rank: Super Contributor
timestamp: November 22, 2015, 04:01:47 pm
content: Quote from: IanB on November 20, 2015, 05:20:27 pmNo, that's no substitute for a test. Anyway, bulk cells from a distributor don't have a date.

author: edavid
author_rank: Super Contributor
timestamp: November 22, 2015, 04:02:35 pm
content: Quote from: Artlav on November 20, 2015, 10:11:05 pmI think that must of have been a paper about rechargeable cells. None of those issues are relevant to a simple acceptance test on a primary cell.

author: IanB
author_rank: Super Contributor
timestamp: November 22, 2015, 08:40:08 pm
content: Quote from: edavid on November 22, 2015, 04:01:47 pmThen I think you have to make your own definition of what is acceptable. For instance, specify the source and part number of the cells you will be buying, obtain some samples, test them, record the results of the tests. To test: measure the open circuit voltage on receipt, run a controlled discharge test to verify the capacity and freshness of each cell thus measured, eliminate bad cells from the data, determine mean and variance of good cells' voltage over a suitable sample size.Having done this, use the expected voltage to test purchased cells. If the source of the cells ever changes, reestablish the metrics by repeating the sample analysis. Bear in mind that cells from different sources can have variations in cell chemistry that will change the measured voltage. They may all be "lithium/manganese dioxide", but there are many details that may be varied within that scheme.
CR2032 powering a micro, inrush current question ? - Page 1
Forum section: electronics / projects

author: MadScientist
author_rank: Frequent Contributor
timestamp: April 09, 2021, 03:43:15 pm
content: It has been suggested to me that I need slew rate limiting on the voltage from a CR2032, when the battery is changed as the low ESR caps are discharged and a relative high inrush occurs that can cause ringing leading to the potential to exceed the micros absolute max voltageI would have thought the relatively high ESR of a typical CR2032 lithium cell would self limitwhats the collective wisdom on this , The suggestion being to add a SIP32431 inrush/slew rate limiter chipThanks

author: MikeK
author_rank: Super Contributor
timestamp: April 09, 2021, 04:03:06 pm
content: A coin cell can't provide large current. In fact, it's been shown many times that you can connect an LED to a coin cell without a current limiting resistor.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 10, 2021, 02:24:31 am
content: Quote from: MikeK on April 09, 2021, 04:03:06 pmNot true with rechargeable coin cells, those can supply a surprising amount of current for their size.

author: tszaboo
author_rank: Super Contributor
timestamp: April 10, 2021, 08:07:21 am
content: 1) why dont you measure it?2) Very unlikely.3) Maybe add a TVS diode for good measure, but you should have that in any case, because user touching exposed metal parts in your device.

author: tooki
author_rank: Super Contributor
timestamp: April 10, 2021, 02:08:23 pm
content: Quote from: NiHaoMike on April 10, 2021, 02:24:31 amYeah, but the C in CR2032 defines the battery chemistry as a lithium manganese dioxide primary cell, so it’s by definition not a rechargeable cell.

author: exe
author_rank: Unknown
timestamp: April 10, 2021, 02:19:07 pm
content: Quote from: MadScientist on April 09, 2021, 03:43:15 pmI feel like counter-acting this "problem" with other solutions (like, slew-rate controllers, etc) will cause other problem. If problem is proven to exist, I'd add a soft-start switch made of a mosfet and gate resistor.PS Afaik ringing requires inductance. Short traces should also help.

author: MadScientist
author_rank: Frequent Contributor
timestamp: April 10, 2021, 03:30:12 pm
content: Thanks guys
Cracked flyback core? - Page 1
Forum section: electronics / projects

author: metertech58761
author_rank: Frequent Contributor
timestamp: June 10, 2024, 06:09:51 am
content: So, I have a vintage 1980 'dumb' terminal that was adapted for use by the deaf in talking to each over a landline.The core technology was developed by Micro-Term of St. Louis, but I do not know if these were assembled by them, a subsidiary, or sold as kits to the company that made these terminals.ANYWAY, these terminals used pre-assembled CRT modules built by Zenith - they have an edge connector on its main board.Pretty straightforward; it just needs +12, ground, H & V sync, video, and brightness pot.Thing is, all but one of these I've seen over the years has had the nuts on the clamp U-bolt torqued down JUST a bit too much to where there is a visible crack in the ferrite core.(the one I currently have, has two)Depending on the location and severity of the crack, the cracked core manifests as anything from visible 'ringing' at the left side of the screen to severe horizontal foldover spanning a good third of the screen. This one is surprisingly one of the better ones; it merely has a bit of ringing visible. I should add, this was with it on for a few minutes; it occurs to me the possibility that the ringing would eventually erupt into full foldover if ran long enough...Am I correct in assuming there is no 'magic' method to heal the cracks, and that if I monkey around with the tension on the clamping bar nuts I risk completely ruining the flyback?Picture is of a terminal and spare module I had years ago. The flyback on the unit I have is mounted on the main plate, not up on the upright as in the picture.

author: moffy
author_rank: Super Contributor
timestamp: June 10, 2024, 06:21:42 am
content: Once it cracks it is never the same, perhaps some super glue if you can bond it well without air gaps and if you can relieve the mechanical stress on the core.

author: Phil1977
author_rank: Frequent Contributor
timestamp: June 10, 2024, 07:10:12 am
content: I´d use super glue only as a very last resort - if the glue fills up any crack then the ferrite core may be completely destroyed. As long as you just press the broken parts together and keep the gap as small as anyhow possible there is a better chance of keeping the magnetic properties in an acceptable range.I had best experiences with tightly applied kapton tape. Maybe you can use glue on the outside of the tape to further stabilize everything.

author: metertech58761
author_rank: Frequent Contributor
timestamp: June 10, 2024, 02:42:01 pm
content: I guess I kinda answered my own question... I see that the ferrites are partially potted into the flyback too. NUSPI.OTOH, the CRT is still good and may be of use to someone to "repower" a worn monitor.Years ago, I had scavenged a good GREEN CRT (the bulk were the plain ol' monochrome ones) and an undamaged flyback I planned to put into one of these terminals.Unfortunately, the museum was 'cleaned out' for move to storage before I could get back in to work on the terminal.Oh well - thanks for confirming my suspicions.
Crap solder paste ? Chip Quik Solder Paste Vs Mechanic Solder Paste  - Page 1
Forum section: electronics / projects

author: diyaudio
author_rank: Frequent Contributor
timestamp: December 11, 2018, 06:06:23 pm
content: So, I used my last amount of solder paste (Mechanic Solder Paste) and surprisingly (2 years old) it still worked i.e I was able to reflow the new components (I was very surprised)https://www.ebay.com/itm/MECHANIC-Reparing-Solder-Soldering-Paste-XG-50-XG-500-Sn63-Pb37-25-45um/381567863146After that ordered some "decent" Chip Quik TS391AX50 from Digikey, To say the least I was very disappointed with the results, the solder joints are partially activated, have tiny balls after bonding and leaves a lot of partially activated residual between components leads leading to shorts, its nothing compared to cheap Mechanic solder paste, also I checked Digikey sold me paste that has a shelf life of 1 year, manufactured date was 2018/03/13, and sold in 2018/08/27... 4 months away from its official ending shelf life as I started using it today.https://www.digikey.co.za/product-detail/en/chip-quik-inc/TS391AX50/TS391AX50-ND/7802229Any comments on this product ?

author: schmitt trigger
author_rank: Super Contributor
timestamp: December 11, 2018, 06:57:11 pm
content: The Chip Quick is a no-clean solder paste.And....do you know exactly what type of flux is being employed on the Mechanic's Paste? Of course not, it does not say.Your soldering conditions may not be optimized for the Chip Quick paste. Or perhaps the Mechanics use a more aggressive flux that requires mandatory cleaning.Either way, you are not comparing apples to apples.

author: jmw
author_rank: Frequent Contributor
timestamp: December 12, 2018, 05:04:49 am
content: I've used the leaded Chip Quik paste and haven't experienced the issues you've described. I find it's more difficult to spread than I'd like and can see there could be problems if you don't have good process control over stenciling. I also felt a bit burned ordering from Digikey and getting months old paste.
CrapXon Capacitors - Page 1
Forum section: electronics / projects

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: February 07, 2022, 05:38:24 pm
content: I have been plagued by the most horrendous RF interference on MW/SW.Which given I have taken to restoring some old AM radios has turned out to be much more than really annoying.Everywhere in the house, across the road, up the garden.Renders MW (and a lot of SW) absolutely unlistenable except for very strong stations.Today turned off each ring main and hey presto I find it's radiating from my own house.A crappy SMPS. I sawed it open and even less surprising, one of the CrapXon capacitors has blown its guts out. Oh, it's a "105 degC" rated one. But we know what to make of that. Print is cheap.This thing has been powered 24x7, but probably actually been loaded (at 1/3 of its rated current) for 1 minute per week, if that.Anyway, consigned it to landfill, where it belongs.Goodness knows how much of this rubbish is pulluting the airwaves.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 07, 2022, 10:41:34 pm
content: What date was on it (the cap, any parts inside, adapter itself)?Tim

author: magic
author_rank: Super Contributor
timestamp: February 07, 2022, 11:28:55 pm
content: Crappy ringing choke converter, 1N4001 for 2A of output, caps undersized for the ripple, AWG28 output cable, all the good stuffI have seen one where the chassis became soft and deformed, one where the input connector partly broke off the board and arced, another where the rectifier desoldered itself and left a blob of tin rattling inside, that's surely not the end of it
Overkill guitar circuit - Page 1
Forum section: electronics / projects

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: April 05, 2020, 09:15:58 pm
content: so I went on a goal to make a circuit capable of having every combination possible with 2 humbucker pickups, it's really complicated (to me at least), I think it's genius how it does the switching cause I thought it up on my free timeand I don't even know how I'm gonna fit it in my guitar.it's based on a Teensy 4.0, and you can just look at the schematic:https://easyeda.com/EdLS/guitar-circuitand yes I had to put my name all over it, otherwise, I have nightmares about someone stealing my circuits and getting all the credit for it.I know why you wouldn't have all this circuit in a guitar, but I want to experiment with it.what are your thoughts? maybe I should change something? also, I intend to have an external box that has a linear power supply for the power supply rails.

author: Cyberdragon
author_rank: Super Contributor
timestamp: April 07, 2020, 03:38:39 pm
content: I have nightmares about guitars that need a whole 5-pin XLR to connect it...

author: obiwanjacobi
author_rank: Super Contributor
timestamp: April 08, 2020, 07:46:21 am
content: I would first try a prototype setup where you test if the GS4157-CR switch you intent to use actually works with the high impedance passive pickups.I did not know these and not sure if the 2.8 ohm will cause an issue (probably not - unless there are a lot in series).Music Man brought out a model they called 'Game Changer' that had a similar concept. Completely programmable.I did give this subject some thought myself:You could also think of throwing in some digital pots to color the sound (tone) and set the amplitude (volume) for each pickup.Have presets in your guitar for several favorite settings which can be easily selected by a multi-position switch (more than 3 settings would be my choice)Support MIDI-in to get your guitar to switch guitar 'presets' when you change presets on your effects unit.Would love to hear how this goes.

author: OwO
author_rank: Super Contributor
timestamp: April 16, 2020, 12:24:48 pm
content: I've never heard of analog switches that draw 80mA; it is probably the maximum rated thru current and not quiescent current.

author: obiwanjacobi
author_rank: Super Contributor
timestamp: April 16, 2020, 12:30:35 pm
content: I see an idle current of 1uA but nothing else to be concerned about (quick scan)https://datasheet.lcsc.com/szlcsc/1912111437_Gainsil-GS4157-CR_C280709.pdfMaking a simple prototype can also shed light on that subject...?

author: obiwanjacobi
author_rank: Super Contributor
timestamp: April 16, 2020, 01:48:12 pm
content: I interpreted that as max current to sink or source...?More a load thingy..?
crazy question: where to find a flatpack lead-forming die - Page 1
Forum section: electronics / projects

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 26, 2019, 06:50:36 pm
content: Does anyone recognize this type of tool and what company would have made them back in the day?I'm looking for keywords so I can buy one. Maybe the Smithsonian has one ...in the basement...

author: jmelson
author_rank: Super Contributor
timestamp: May 26, 2019, 10:11:01 pm
content: Lead forming tool, but I suspect you will have a VERY hard time finding one. But, they are not that complicated, you should be able to have a machine shop create the dies needed, and then mount them to a small arbor press. We had our shop make up some custom tooling, and they mounted it in a little arbor press that stands about 4" tall.Jon

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 26, 2019, 10:51:23 pm
content: Thanks, do you also happen to know what KE stands for? There's another picture with precisely an arbor press and the only text I can make out is KE which looks like a manufacturer's logo. A company I suspect that is as dead as flatpacks.BTW, do you know what logic family TI called "925" back in the 1960s? Many TI flatpacks have 925 printed on them in the pics I have.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 26, 2019, 11:09:57 pm
content: The tool I see in my book has two actions, it forms the leads and cuts off the excess. It doesn't look like something I can just improvise I think.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 26, 2019, 11:35:03 pm
content: argh, that "KE" was gnawing away at my brain stem, that's whyhttps://en.wikipedia.org/wiki/Keuffel_and_EsserDon't think they also made lead forming tools...
CRC-8 Code for checking Communication - SMBus - Page 1
Forum section: electronics / projects

author: ulix
author_rank: Regular Contributor
timestamp: May 08, 2016, 10:21:11 am
content: Hi,I'm trying to implement a crc-8 algorithm to check received messages from a sensor.There is some code around, but it doesn't work, and I don't really know what's wrong with it...Code:uint8_t_crc8_ccitt_update (uint8_t inCrc, uint8_t inData){uint8_t i;uint8_t data;data = inCrc ^ inData;for ( i = 0; i < 8; i++ ){if (( data & 0x80 ) != 0 ){data <<= 1;data ^= 0x07;}else{data <<= 1;}}return data;}I have the following message, inData: 0xB627B75B3Cwith inCrc:0.And the result should be: 0xF5See correct calculation:https://www.ghsi.de/CRC/index.php?Polynom=100000111&Message=B627B75B3CI would be very grateful, if anyone could help me out...

author: Andy Watson
author_rank: Super Contributor
timestamp: May 08, 2016, 11:16:18 am
content: Quote from: ulix on May 08, 2016, 10:21:11 amWorks for me.How are you feeding the data into _crc8_ccitt_update ?

author: ulix
author_rank: Regular Contributor
timestamp: May 08, 2016, 11:29:59 am
content: I think there is my fail, I did give the data like this:Code:_crc8_ccitt_update (0, 0xB627B75B3C)but I should give it like this:Code:_crc8_ccitt_update (0, 0x3C), then _crc8_ccitt_update (0, 0x5B) and so on...right?

author: Andy Watson
author_rank: Super Contributor
timestamp: May 08, 2016, 11:33:31 am
content: Yes. That would be a problemI am surprised that your compiler did not issue a warning.

author: ulix
author_rank: Regular Contributor
timestamp: May 08, 2016, 11:34:46 am
content: Thanks a lot, I should have found out myself!I only wanted to get is finished,

author: ulix
author_rank: Regular Contributor
timestamp: May 08, 2016, 12:05:53 pm
content: Sorry,I'm not gone, yet...When I calculated the segments, what happens with them?can't see it... no and/xor/or...Like for:3C is crc-8=B45B is crc-8=86B7 is crc-8=C27 is crc-8=F5B6 is crc-8=Bi check it the the online calc...

author: Andy Watson
author_rank: Super Contributor
timestamp: May 08, 2016, 12:37:56 pm
content: This is a simple "wrapper" that I wrote to check the code:Code:* Simple CRC 8 check */#include <stdio.h>#include <stdlib.h>typedef unsigned char uint8_t;uint8_t _crc8_ccitt_update (uint8_t, uint8_t );int main(void){unsigned char inData = {0xB6,0x27,0xB7,0x5B,0x3C };int bcount;unsigned char answer,data;answer = 0;for (bcount=0;bcount<5;bcount++) {data = inData;answer = _crc8_ccitt_update (data,answer);printf("\nAt %i, answer is %02x",bcount,answer);}printf("\ndone\n");exit(0);}The result is given in "answer". Note that you should be able to check the operation of the code by fixing the answer byte to the end of the string of bytes. Running the CRC on this augmented string should return the answer as 0.Edit: I'm guessing from your previous output that you have input your data string in reverse. This is what I see at each stage:At 0, answer is 0bAt 1, answer is c4At 2, answer is 5eAt 3, answer is 1bAt 4, answer is f5
CRD alternative - Page 1
Forum section: electronics / projects

author: ArturN
author_rank: Newbie
timestamp: August 17, 2019, 12:17:40 pm
content: Hello,Recently i designed some device in which i needed to limit current.I used CRD (Current Regulative Diode).For example this:https://pl.mouser.com/ProductDetail/Semitec/S-202T?qs=sGAEpiMZZMtjJbtednZihoE8nwVXbu0dMy question is that what is the cheapest alternative to this device?I found only current limiter based on JFET's.Any ideas?

author: David Hess
author_rank: Super Contributor
timestamp: August 17, 2019, 07:35:49 pm
content: I assume you mean exclusively for two terminal devices.LM317s can be configured to provide a constant current. The LM334 is an integrated current regulator. Depletion mode MOSFETs can be used in place of JFETs. The LM10/LT1635 operational amplifier and reference is also useful as a basic building block to make current regulators.

author: Benta
author_rank: Super Contributor
timestamp: August 17, 2019, 09:36:06 pm
content: J507

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 18, 2019, 05:01:25 am
content: Depending on the circuit requirements, you might be able to use a current source based around a bipolar transistor, two diodes, and two resistors.