hybridfree/eevblog-posts huggingface dataset:
How to offset or shift of voltage - Page 1
Forum section: electronics / beginners

author: Circuitous
author_rank: Unknown
timestamp: July 29, 2013, 05:45:05 pm
content: Mostly, I stick to the digital side, so I haven't done a lot with op-amps, but...I need to measure the AC output voltage of a transformer. Not across the entire range, I’m really only interested when the voltage is between 6.8V and 11.4VAC, anything outside that will be a brownout or over-voltage situation. So, to get good resolution on the ADC, instead of just using a voltage divider, I’d like to shift the input voltage down to be a 0-4.096V range, without compressing the range any more than necessary.What methods do you recommend to offset the voltage like that?

author: Neilm
author_rank: Super Contributor
timestamp: July 29, 2013, 05:57:23 pm
content: Dave did a video on peak hold circuits - probably about a month ago [Edit it is episode 490]. I would rectify the signal and use one of them with an op amp following the peak hold circuit to divide the signal down by 4.Neil

author: olsenn
author_rank: Frequent Contributor
timestamp: July 29, 2013, 06:00:50 pm
content: Google "voltage clamp"

author: Circuitous
author_rank: Unknown
timestamp: July 29, 2013, 10:13:23 pm
content: I can implement a voltage divider, that's easy, but I loose the resolution. I really want to shift that voltage down and take full advantage of the ADC's range.@olsenn: Hmm... "negative biased voltage clamp", looks like the right direction for me to head in. I had tried something similar, but not quite. I'll try some variations of that tonight. Thanks.

author: SebG
author_rank: Regular Contributor
timestamp: July 30, 2013, 06:22:24 am
content: Hi. You could use a voltage divider and still get a full range ADC reading by using Vref- as the bottom reading value. For example if you divide the input voltage by 2.8 and use a Vref+ = 4.096 and Vref- of 2.4V (which you can make using another voltage divider and maybe a capacitor or voltage follower) the full scale range will be 4.096V x 2.8 = 11.4688V down to 2.4V x 2.8 = 6.72V (ie. 11.4688V - 6.72V) This however makes the math a bit more complicated since (if using say 10 bit ADC) each bit's value will represent (11.4688 - 6.72) / 2^10 = 4.6375mV. So if you get a ADC reading of say 128 the voltage measured will be (128 x 0.0046375 V) + 6.72 = 7.3136V.Don't forget to ensure the voltage at the input to the ADC is not less then ground when the AC voltage swings to it's negative side. This could cause latch up or excessive current flowing.
How to order a switch - Page 1
Forum section: electronics / beginners

author: NikkiC
author_rank: Contributor
timestamp: December 09, 2019, 06:49:37 pm
content: I'm confused about how to order switches online from sources like Mouser. My project needs a simple illuminated SPST panel switch to turn my project OFF/ON. You know, you press the button and it turns the project ON and illuminates. Press it again and it turns off. What could be simpler right?Well I am really confused by the nomenclature used when describing the switch function.Such as: OFF - (ON) , or OFF - ON. Which one is momentary and which one isn't? WTF they can't just say it is a momentary switch or not instead of making it a secret squirrel grab bag? I'm a bit frustrated by such a simple thing. So I am going to make an educated guess and say the one I am looking for (which is definitely NOT a momentary) would be OFF - ON. I am assuming the parentheses implies momentary. I would appreciate it if someone could confirm this is correct or not. Such a simple thing, but not necessarily so if you don't know the nomenclature.TIANikki

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: December 09, 2019, 07:04:33 pm
content: Correct, the parenthesis indicates a momentary position for the switch.

author: rrinker
author_rank: Super Contributor
timestamp: December 10, 2019, 08:05:10 pm
content: That's pretty much standard notation, a position with parentheses is momentary, without is latched. Much cleaner to put parentheses around something instead of making a database field for momentary - and there are many variations wit momentary positions - you can get switches that are (ON)-OFF-ON, for example, double through momentary one way, or fixed on position the other.Something else you can do is, if you see one that looks nice, pull up the manufacturer's data sheet and see if it is available in the style you want, SPST illuminated. Though the parametric search on Mouser and Digikey can do a pretty good job of pointing to exactly those that meet your criteria. But if you see one that looks like it would match your project design but are unsure, the data sheet would tell you if the manufacturer makes a switch that looks like that and has the function you are looking for. The datasheet will give you a part number, based on the options you want, and then you can search by that part number to find price and stock status.Dave did a video a while back on doing parametric searches on the distributor web sites like Mouser and Digikey - worth watching if this is fairly new to you.
How to physically connect AS3933 to 3D antenna? - Page 1
Forum section: electronics / beginners

author: filthyfrank
author_rank: Newbie
timestamp: June 13, 2019, 04:53:26 pm
content: How to physically connect AS3933 to 3D antenna?I’m trying to breadboard LF frequency receiver circuit using AS3933 (https://www.digikey.se/product-detail/sv/ams/AS3933-BTST/AS3933-BTSTCT-ND/3028676) receiver chip IC and CAS143-147 3D antenna chip (https://www.digikey.se/product-detail/sv/sumida-america-components-inc/CAS143-47/308-2270-1-ND/4356340). However I don’t understand how can I connect AS3933 pins to CAS143 on a breadboard. CAS143 seems to be a SMD chip and it has some weird spacing between it's pins (see image attached) so I can't use standard TSSOP/SOIC to DIP adapters. Does anyone has any suggestions about connecting those two?
How to pick a proper fuse? - Page 1
Forum section: electronics / beginners

author: redgear
author_rank: Frequent Contributor
timestamp: September 03, 2020, 07:19:40 am
content: ThePSUhas a nominal input current of 0.15A and has a peak inrush current of 40A. No info about how long the inrush current lasts is given.The ballast has a nominal current rating of 1.5A with a max peak inrush current of 21A lasting for 185 microseconds.After reading the Little Fuse'sguide, I got some info on how to account for these inrush currents while selecting a fuse. I do not have an idea about the waveform of the inrush current so went with the waveform that will give me the maximum i2t value from chart 1 in the guide.For 100,000 cycles I get a i2t value of 0.185. So a 2A fuse with a i2t value greater than 0.185 should be used as F1, am I right? How do I calculate i2t for F2 where I don't the time period of inrush current? The F3 is to protect the micro and 7 seg display? Will a fast blow 1.5A fuse be a right choice? Cos I don't have both inrush current or timeperiod to calculate the i2t.Also, I need a fuse as soon as the mains enter, will a 3A fuse with the greater i2t value(F1) be a right choice?Thanks

author: wizard69
author_rank: Super Contributor
timestamp: September 04, 2020, 01:49:31 am
content: I don't have a good answer for you because most of my experience has been industrial. Branch circuit protection there is about meeting NFPA/NEC code. Device protection is attempted but to be honest protecting some devices with fuses is a bit like swimming upstream. Generally the device fails thus blowing a fuse. If this is the case it really doesn't pay to set the fuses to close. In the end you may need some history with the device to get an optimal fuse size.

author: Raj
author_rank: Frequent Contributor
timestamp: September 04, 2020, 05:42:31 pm
content: correct me if I'm wrong. But you'll need a slow burn fuse with a little more than 0.15A rating and fast burn fuse with little more than 40A rating

author: thm_w
author_rank: Super Contributor
timestamp: September 04, 2020, 09:02:13 pm
content: Quote from: redgear on September 03, 2020, 07:19:40 amCan you measure it?That IRM-10-5 module has a maximum output current of 2A and overload protection already, so I don't know if I'd even bother with a fuse on the output.But you could throw a 1 or 1.5A 0603 fast blow on there sure, if you want.. Assuming the maximum current consumption of the circuit is <0.5A.

author: chris_leyson
author_rank: Super Contributor
timestamp: September 04, 2020, 09:40:10 pm
content: I think the best approach would be to measure the power supply inrush current under worst case conditions, maximum VAC and switch on at the peak. You would get a better estimate of i2t for the power supply.
How to pick the correct rated Fuse to protect my Arduino project - Page 1
Forum section: electronics / beginners

author: pete1111
author_rank: Contributor
timestamp: June 04, 2016, 01:01:38 am
content: Hi,just wanted to ask for some help pleasei have an arduino project that i have painstakingly made a PCB design in Eagle and i was wondering i should probably protect it with a fuse.my project consists of an arduino pro micro (SparkFun Version) running on 5v (from a pc ATX power supply)it is connected to a 20x4 LCD (Backlit) and it simply displays 4 temperature readings from 4, TMP36 sensors.there is a 3mm blue led also connected to the arduino.i was thinking on using this Fuse ?resettable 1812 msmd050-15v 500ma 15v auto recovery fuse pptc a6I have a crappy M-830B multimeter

author: danadak
author_rank: Super Contributor
timestamp: June 04, 2016, 01:43:51 am
content: Whats the sum total of all worst case component current ?Regards, Dana.
How to power a Nixie tube? - Page 1
Forum section: electronics / beginners

author: Azhar
author_rank: Regular Contributor
timestamp: July 06, 2013, 10:28:13 am
content: Do we need to build a circuit to light up a Nixie tube? or we can do it with just a power source?

author: amyk
author_rank: Super Contributor
timestamp: July 06, 2013, 10:57:05 am
content: Depends how you want to light it up...

author: Azhar
author_rank: Regular Contributor
timestamp: July 06, 2013, 11:15:09 am
content: I have a ten digit Nixie tube, and wanted to light up the digits one by one! is that possible by applying voltage directly to it?

author: Psi
author_rank: Super Contributor
timestamp: July 06, 2013, 11:24:34 am
content: You could just have 10 switches but you need a high voltage source.Just how high a voltage depends on the nixie tube you have.

author: Azhar
author_rank: Regular Contributor
timestamp: July 06, 2013, 11:29:44 am
content: Does that mean, they work normally like any LED display? I don't need another power source to heat a filament for example?

author: Paul Price
author_rank: Super Contributor
timestamp: July 06, 2013, 11:43:09 am
content: The Nixies require a low-current, Usually unregulated, approx 140V to 170V (depending on the Nixie type)power source connected to a common anode and a current limiting resistor is connected to each numerical or other symbol display cathode pin. The other side of the current limiting resistor connects to the collector of a HV small transistor that is turned on and off at logic level voltages with a resistor to its base, and the emitter of the Nixie driver transistor connects to ground.Sometimes a small pot-core transformer is used with a oscillator circuit to generate a 140V source from a logic level power supply voltage.for more info,http://en.wikipedia.org/wiki/Nixie_tube

author: Azhar
author_rank: Regular Contributor
timestamp: July 06, 2013, 01:31:02 pm
content: Thanks a lot! thank you all
How to power an LED strip from a LED  monitor? - Page 1
Forum section: electronics / beginners

author: dmkfeatf14
author_rank: Newbie
timestamp: June 20, 2015, 02:50:39 pm
content: Hi, I recently obtained an LED strip that I had removed from a broken screen of a friend's notebook display. I am trying to reuse the LED strip to make a desk lamp out of it. Does know the pinout coming off the ribbon cable of the LED strip? Thanks!

author: electr_peter
author_rank: Unknown
timestamp: June 20, 2015, 09:06:05 pm
content: Hello,It would be much easier to help you if you could provide a picture and more info about LED strip you have.Your LED strip could be a simple circuit of LEDs in series/parallel configuration or it may have a driver on board as well. In former case, you would need to build a constant or limited current DC power supply. In latter case, you would need a DC power supply and MCU to send commands to LED strip driver.This would be a relatively easy project if you know something about electronics and have circuit making skills.
How to preserve tin paste? - Page 1
Forum section: electronics / beginners

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: February 07, 2021, 03:43:39 pm
content: About two months ago I did a job with paste tin, this was new, today I am going to use it and it is hard, it was well covered and in a cool place, does anyone know what it is revived with, with alcohol?

author: mvs
author_rank: Frequent Contributor
timestamp: February 07, 2021, 04:18:43 pm
content: Quote from: Adrian_Arg. on February 07, 2021, 03:43:39 pmMake it warm and add some gel flux, like RMA223 or NC559.For the next time, i would rather recommend you to buy paste in a syringe.--Glycerine may also work well, except that it needs to be cleaned.It is great surface tension modifier for solder. I use it for tinning tracks on self made PCBs.

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: February 07, 2021, 04:48:59 pm
content: ok, thanks to the two

author: strawberry
author_rank: Super Contributor
timestamp: February 07, 2021, 09:52:52 pm
content: QuoteFlux and solder in room temperature may separate and left/leak on syringe internal walls, therefore solder paste will bee too thick to get it out easy

author: tooki
author_rank: Super Contributor
timestamp: February 08, 2021, 06:57:12 am
content: Quote from: blueskull on February 07, 2021, 04:00:49 pmFor what it’s worth, I’ve had no trouble with the low-temp ChipQuik — at least not with fresh components and PCBs. I haven’t tested it with older, more oxidized parts.

author: tooki
author_rank: Super Contributor
timestamp: February 08, 2021, 11:12:39 am
content: Ah ok! I’ve tried their regular low-temp, and no-fridge regular temp, but not the combination!

author: jmelson
author_rank: Super Contributor
timestamp: February 08, 2021, 09:30:41 pm
content: If you can get butanol (the 4-carbon alcohol) it is a low vapor-pressure solvent that seems to be the magic ingredient in many pastes.I managed to get a bottle of it, and add just a few drops to the paste any time it seems too stiff. Then, you have to stir it in real well.Jon

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: February 08, 2021, 11:10:30 pm
content: I'm going to see if in this blessed city it is achieved!
How to program CPLD and what jtag programmer do I need? - Page 1
Forum section: electronics / beginners

author: PotatoBox
author_rank: Regular Contributor
timestamp: July 26, 2020, 03:42:17 am
content: Hello,I'm looking to build this project:https://www.lighttech-hg.de/index.php/open-source-projects/a2000-scandoublerbut I need to program a Xilinx XC95144XL cpld and I've never used cpld's or fpga's before. What kind of hardware do I need to program a device?Thanks,

author: ebclr
author_rank: Super Contributor
timestamp: July 26, 2020, 03:59:06 am
content: You will need something like thishttps://br.banggood.com/Xilinx-Platform-Cable-USB-FPGACPLD-Download-Cable-Downloader-p-1364842.html?cur_warehouse=CN

author: james_s
author_rank: Super Contributor
timestamp: July 26, 2020, 05:06:18 am
content: Yep, Xilinx platform USB cable, the Chinese clones work fine. You'll also need Xilinx ISE webpack which you can download for free.If you want to try Altera CPLDs/FPGAs those use the cheaper "Byte Blaster" USB cable and Quartus II.
How to program eeprom of CDCE925PWR - Page 1
Forum section: electronics / beginners

author: gmipf
author_rank: Newbie
timestamp: May 08, 2024, 03:14:04 pm
content: I wanted to replicate this pcb:https://github.com/consolesunleashed/sony-playstation-multi-output-frequency-oscillatorThe gerber files, bom and hex for the eeprom all are there. But I don't know how to program the hex to the CDCE925PWR. There is the official programmer CDCEL9XXPROGEVM but that is too expensive for just one time use.Here is the backside of the pcb from gerber:There are SCL and SDA points on the pcb and the datasheet talk about I2C support.Datasheet:https://www.ti.com/lit/ds/symlink/cdce925.pdf?spm=a2g0s.imconversation.0.0.17993e5fIrszCt&ts=1715105157124See chapter: 9.3.3 SDA/SCL Serial InterfaceI have an XGecu T56, there seem to be no support for that clock chip. Is there a way with my or any other cheap general purpose flasher to program that chip?

author: aliarifat794
author_rank: Regular Contributor
timestamp: May 09, 2024, 06:25:35 am
content: I was going to suggest a universal programmer. Then I noticed that you've already tried that. Since CDCE925PWR is manufactured by Texas instruments, I think it's better to ask them to suggest a compatible programmer. They must have one.

author: gmipf
author_rank: Newbie
timestamp: May 09, 2024, 11:06:10 am
content: Texas Instruments has their own one, the CDCEL9XXPROGEVM. But that alone costs over 100USD. I better want to invest to a device that is more multipurpose.

author: m k
author_rank: Super Contributor
timestamp: May 12, 2024, 07:26:53 pm
content: Protocol is standard so use Arduino.

author: gmipf
author_rank: Newbie
timestamp: May 16, 2024, 01:30:27 pm
content: I have found some alternatives now, one is a DIY board based one:https://circuit-board.de/forum/index.php/Thread/18016-DFO-Dual-Frequency-Oscillator/And another Raspberry Pi based:https://github.com/nostalgic-indulgences/cdceprog
How to properly implement Bluetooth modules? - Page 1
Forum section: electronics / beginners

author: SolarSunrise
author_rank: Regular Contributor
timestamp: March 29, 2015, 08:18:49 pm
content: I've read from multiple sources that bluetooth antenna would get detuned if covered by a plastic enclosure. My question is, how do I properly use a bluetooth module in my project (RN42 or SPBT2632C1A.AT2) with a plastic case? In my case, the communication requires a very fast baud rate (~500k) along with a very stable connection (very few packet losses). So how do I solve this issue without using a network analyzeror running a complicated simulation? Or am I being too paranoid about these kind of things for a one-off project?Thank you in advance!
How to properly set up a Keysight 53230A to capture a 1PPS signal - Page 1
Forum section: electronics / beginners

author: pmembrey
author_rank: Newbie
timestamp: May 01, 2016, 08:02:36 pm
content: Hi guys,I'm looking to measure and characterize the 1PPS output of a uBlox MAX M6Q using a Keysight 53230A. Specifically, I'm mostly interested in the period of the signal, how close it is to exactly 1Hz and how that signal deviates over time.The Keysight is connected to the 10Mhz output of a SRS FS-725 Rubidium Frequency Reference which is being disciplined by a PPS from a microsemi S600 GPS.I've currently got the channel configured as follows:* DC* 50Ohm* Bandwidth filter enabledThe default gate time is 100ms, which if I leave it configured for that, it will never show a reading. I can get it to start giving a reading if I set the gate time to 3 seconds but for reliable readings, I need to set it to at least 5 seconds.So, here's my questions:1. I would like to capture the period of each pulse - is this doable with my set up?2. What does gate time actually mean? I've read a number of descriptions, but I'm still not 100% clear on what it means in this context and what impact it has3. How exactly does the gate time work in this case? I mean if it captures data over 5 seconds and gives one reading - what actually is that reading? An average? One of the samples?4. Should I be doing anything differently?Ideally, what I'd like to do is capture the period of each pulse individual so that I can do an Allan variance on the data over a period of time.I've googled around and I've read numerous guides, but they mostly seem to cover faster signals (like 10Mhz sine wave) rather than the much slower PPS. I've looked at Dave's videos, and although I found some awesome ones on counters (and learned a lot I must say), I didn't find anything directly addressing this - although that could well be me searching for the wrong thing.Thanks in advance for any advice or guidance!

author: jpb
author_rank: Super Contributor
timestamp: May 01, 2016, 08:11:55 pm
content: I think that you want to use time-stamp mode which should measure every rising edge giving them time-stamps. The 53230 has a lot of memory so you can just save all the measurements and analyse them later.(I don't have the 53230, I use the Tektronix FCA3100 which has similar functionality).

author: pmembrey
author_rank: Newbie
timestamp: May 01, 2016, 09:03:12 pm
content: Thanks for your quick reply!I've just given that a go, but as soon as I select time-stamp mode, it stops displaying any results. I can see the Gate indicator and it flashes about once per second. If I go into the Time Interval section and select Rise Time, I am able to track and record that no problem - I just don't seem to be able to do it with a time-stamp...
How to protect a microcontroller on a high voltage PSU - Page 1
Forum section: electronics / beginners

author: msalko
author_rank: Newbie
timestamp: February 07, 2018, 07:14:14 pm
content: Hello,I'm building a high voltage power supply, and so far i had problems with high voltage "creeping" into my microcontroller, which causes it to restart.What I'm building is essentially a l293d connected to a transformer and an MCU, i know how bad this sounds, buuut i still want to try it.My question is what is the best practice to isolate the rails of the MCU and the l293d, I'm looking mostly for advice for what to do, since i can't get any measurements on it. (I don't have an oscilloscope)I think my problem is the common ground, or the common 5v between the logic part of l293d and MCU, or the crystal being close to pins connected to l293d.I also have this feeling that the reverse diodes in the l293d might not be good for protecting from reverse voltage on a high voltage powersupply.

author: danadak
author_rank: Super Contributor
timestamp: February 07, 2018, 11:22:24 pm
content: Grounding practices, see -https://www.dropbox.com/s/ruaf9booe17jk8n/PCB%20Layout.zip?dl=0http://www.st.com/content/ccc/resource/technical/document/application_note/f7/f4/51/8d/a1/c5/47/8e/DM00182773.pdf/files/DM00182773.pdf/jcr:content/translations/en.DM00182773.pdfLook at input pins terminated by high z loads, they are subject to C coupled pickup.Lead/cable dressing/shielding....If you don't have a scope, but have a PC (limited, will not be able to see high speedtransients, but still somewhat useful) -You can start with a PC sound card based scope for free. Will give you basicallyaudio range scope, spectrum analyzer, and function generator all using yourPC sound card.https://www.zeitnitz.eu/scope_enhttp://www.zelscope.com/http://www.ledametrix.com/oscope/http://www.virtins.com/downloads.shtmlBut first build a simple circuit to protect sound card inputs so you do notruin from transients, overvoltage. Google "protect sound card input".For examplehttp://makezine.com/projects/sound-card-oscilloscope/Sound card impedance bridge -http://www.marucchi.it/ZRLC_web/ZRLC/Steber_An_LMS_Impedance_Bridge.pdfhttp://www.sillanumsoft.org/ZRLC.htmRegards, Dana.
How to protect Analogue Voltmeter - Page 1
Forum section: electronics / beginners

author: Limecc
author_rank: Newbie
timestamp: April 03, 2023, 08:31:56 pm
content: Hi and thanks in advance.A friend acquired a vintage pillar drill and didn't realise it had a 110v DC motor. I had the idea to use a 220v 4kw speed controller into a high power bridge rectifier and happy days, it seems to work well to power the machine. I would have preferred a digital voltmeter (on the panel that houses the components), but had trouble finding one. There was a 0-450v DC analogue meter but I got him the 0-150v version as the scale is easier to read and I wired it on the output of the rectifier.The problem is when there's no load on the controller, the voltage rises and forces the needle off the end of the scale. When the drill is running the voltage drops to 110v DC which was set. I want to protect the meter against damage but am not sure how to go about it. When testing I used a 25w incandescent light bulb to provide a load but I don't want to do that when I could use high power resistor, but what value? 2.7K? Or else how about a current limiting resistor and shunt resistor across the meter? Maybe the controller doesn't need a 25w minimum load? Actually could just disconnect the meter and remove the rotary knob but that's conceding defeat. Left the knob on in case the voltage drops when drilling big holes but in reality it hardly does.https://www.amazon.co.uk/dp/B07BP4N2VPhttps://www.amazon.co.uk/dp/B07Z3ZDWGNhttps://www.amazon.co.uk/dp/B08RMP2FSZ

author: thm_w
author_rank: Super Contributor
timestamp: April 03, 2023, 11:10:19 pm
content: I can't find the specs for that panel meter:https://www.finglai.com/products/instruments/pointer-ammeter-and-voltmeters/85C1/85C1-V.htmlBut similar meters draw 1mA at full scale, so around 150k ohms coil:https://d2pyqm2yd3fw2i.cloudfront.net/files/resources/instructions/9332.pdfYou could have a series resistor and then TVS across the meter, to clamp any voltage above 150V.But the resistor cannot be too large or it affects the accuracy of the meter. Maybe somewhere in the range of 2k to 4k7.What about using the 25W bulb to light what you are drilling? Or would that not work.

author: Limecc
author_rank: Newbie
timestamp: April 04, 2023, 12:08:28 am
content: Why thank you. My friend made the very same suggestion about getting a work light.
How to protect buck output from backflow current from battery? - Page 1
Forum section: electronics / beginners

author: cbc02009
author_rank: Regular Contributor
timestamp: September 29, 2018, 02:23:57 pm
content: Hello all,I'm still working on mppt controller, and I have another question that I can't seem to find an answer for on google.In my schematic, I have a p mosfet on the output of my buck converter to protect from reverse polarity (the gate is tied to ground), but I just realized that a p mosfet won't actually do anything to protect the circuit if the battery has a higher voltage potential than the charger, because Vgs will still be negative because of the voltage of the battery.I figure I could use a schottkey diode, but that's several watts of power loss. Is there a better solution that I'm missing? I'm surprised I can't seem to find anything about this issue online.I'm using a 12V 12ah SLA battery, if that matters.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 29, 2018, 02:55:23 pm
content: How much load is on the buck input side?You can connect FETs in anti-series (i.e., gates together, sources together, wire drain-to-drain for load) for a bidirectional switch, of course it incurs twice the Rds(on), which makes P-ch MOS that much less desirable. There are protection controllers (reverse, UVLO, OVLO, surge) that handle this, if you want a one-chip solution (and don't mind paying for it).Tim
how to pull data of a multimeter on to a pc - Page 1
Forum section: electronics / beginners

author: IamSynthetiC
author_rank: Regular Contributor
timestamp: June 16, 2020, 03:31:14 pm
content: Greetings,I have an old HP 3457A, and a Keithley DAQ6510. I want to control them through the computer and even pull data out of them to do some analysis.The Keithley has software but its it is expansive AF. I had seen a post the other day about a software (in user testing) that could controll several DMMs, but i can not find it.Are there other software that can do this?As for the HP i can get its full functionality with a GPIB cable, but its has been serving me well so far, so i would preffer to avoid getting an expensive GPIB cable if i can.Do you know any alternatives ?Thank you and have a good day.

author: Ian.M
author_rank: Super Contributor
timestamp: June 16, 2020, 05:43:53 pm
content: TheAR488Arduino GPIB interface is supported by the open source SIGROK software, as is your HP 3457A. Your biggest expense would be a male GPIB plug!
How to pull down signal in external circuit - Page 1
Forum section: electronics / beginners

author: frenky
author_rank: Unknown
timestamp: July 26, 2017, 05:56:44 am
content: So I have this old compact camera Pentax Optio W60:I would like to control it with arduino (or attiny85).All I need is control 3 switches: power on, half press and full press of capture button.I already took it apart and all 3 switches pull signal to the ground when in contact.So how do I pull down signal with arduino without risking the damage to the camera circuit?My ideas:In top image I would make D5 output pin with 5V on output. And then output 0V (LOW) when I wanted to pull the camera signal down.In bottom image D5 would be normally at 0V and changed to 5V (HIGH) when I wanted to pull down the camera signal.What would be the most correct way to do it? (Please consider that D1 and D5 are most likely at different potentials when HIGH.)Tnx.

author: Zero999
author_rank: Super Contributor
timestamp: July 26, 2017, 08:27:34 am
content: It's quite likely both circuits will work.The first one, with the diode will probably work because the camera will most likely have a high logic level threshold, less than your MCU's power supply + a diode drop and a low logic level threshold above a diode drop.The second one, with the MOSFET has the greatest chance of working and would be my first choice.

author: frenky
author_rank: Unknown
timestamp: July 26, 2017, 08:53:48 am
content: Thank you.

author: frenky
author_rank: Unknown
timestamp: August 09, 2017, 06:37:05 am
content: It's not pretty but it works.
How to put a device output into a modern TV that originally outputted to UHF/VHF - Page 1
Forum section: electronics / beginners

author: gooseEL34
author_rank: Regular Contributor
timestamp: October 05, 2015, 04:56:42 am
content: Hey all-I was interested in seeing if an old Timex Sinclair still worked and realized that I have no TVs with screw terminals anymore.I was wondering how to get the output of a RF switch into a modern TV? I tried taking the two wires with the spade connectors and connecting them to the pin and shield of a male RCA and then going into the composite IN of the TV but that did not work (maybe it should and my switch is bad?)Thanks for any thoughtsTim

author: sleemanj
author_rank: Super Contributor
timestamp: October 05, 2015, 05:17:56 am
content: https://www.google.co.nz/search?q=rf+to+composite&oq=rf+to+c&aqs=chrome.1.69i57j0l5.3694j0j4&sourceid=chrome&es_sm=93&ie=UTF-8

author: jwm_
author_rank: Frequent Contributor
timestamp: October 05, 2015, 05:24:20 am
content: You can pull the composite video off the board before it goes to the RF modulator if you don't mind a small amount of soldering.http://www.mainbyte.com/ts1000/composite.htmlI recently did a similar mod to get s-video (seperate chroma and luminance) out of a VIC-20. like night and day.
How to put this Skanti RF amp into TX mode??? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: January 01, 2014, 01:18:47 pm
content: I have a Skanti 250W amplifier here, brand new, rescued from a Hamfest. I have the schematic, albeit rather cobbled together from two .jpg files. I have built the required 48V DC supply and used a home brew buck voltage converter to get a 5V @ 3A plus bias supply from the main 48V supply. I have found info on setting the driver and PA bias pots, but no info on how to set it to TX. It would have been part of a ship to shore transceiver. I only have, and only want to use, this solid state amp section. I am not too confident I understand the protection circuitry, and how to set it to TX via the 10 pin header socket designated PL2. At the moment the 48V supply is only having 10mA drawn from it, by the buck converter board. I guess it needs either a voltage input or a short on the ten pin header to go to TX? Would one of you gurus have a peek at the schematic and see if there's enough info there to tell me how to safely try to put it in TX, with no drive, to set the bias levels please? I can't attach the schematic as it's too big, and reducing it may make it unusable. I have put it on my server at:http://www.chriswilson.tv/skanti2.jpgThanks

author: Rory
author_rank: Frequent Contributor
timestamp: January 01, 2014, 06:01:20 pm
content: Looks like you need to apply +24v to pin 3 of PL4 (PA Key).

author: Chris Wilson
author_rank: Super Contributor
timestamp: January 02, 2014, 07:21:19 am
content: Thanks Rory, any idea what pin two's function is? All the best for 2014!

author: Rory
author_rank: Frequent Contributor
timestamp: January 02, 2014, 09:27:31 pm
content: Quote from: Chris Wilson on January 02, 2014, 07:21:19 amAppears to be associated with ALC peak detector and is probably used to enable exciter transmit when amplifier transmit enable is true. Lots of interlock stuff, would be tied in with antenna coupler interlock as well.

author: Chris Wilson
author_rank: Super Contributor
timestamp: January 02, 2014, 09:52:37 pm
content: OK, thanks again Rory, will just try it with low excitation levels into a dummy load and monitor currents and temps and SWR. Much appreciated.
How to re-solder SMT nut / stand-off to motherboard PCB - Page 1
Forum section: electronics / beginners

author: eeprom1
author_rank: Newbie
timestamp: October 10, 2019, 12:15:18 am
content: My computer motherboard has M.2 stand-offs soldered into its PCB.When over tightened one of screws, the stand-off broke off.Good news is that it broke from the soldered joint; the motherboard is fine.Bad news is that this is a very compact crowded computer motherboard.I appreciate recommendations on how to solder the SMT nut back without damaging the board or components.I have access to professional grade soldering station and an pro analog heat gun with 5 mm nozzle.I circled around the nut and its place on PCB in the photo attached.One idea I have was to preheat the nut to reduce the soldering time.

author: ataradov
author_rank: Super Contributor
timestamp: October 10, 2019, 12:36:28 am
content: Epoxy it in place. You will get much better mechanical strength. Use the original screw to align everything
How to read 5V Serial Data with Raspberry Pi? - Page 1
Forum section: electronics / beginners

author: byoder
author_rank: Newbie
timestamp: September 04, 2021, 09:35:17 pm
content: I am working on my first electronics project. Replacing the outdated navigation system in my 2002 Lexus is300 with a Raspberry Pi running Open Auto Pro.https://bluewavestudio.io/I would like to be able to use the controller in the center console. There is one wire running to the display housing where the Pi is, carrying some sort of 5v serial data.How do I begin to go about reading this data from the Pi?https://www.youtube.com/channel/UCE9xWU7e6TUPXOLQ3p-8yRQ

author: jaycee
author_rank: Regular Contributor
timestamp: September 05, 2021, 01:03:34 am
content: Level shifters. More than one way to skin that cat... and boards from the likes of Sparkfun exist if you want something ready made.For this job I'd probably use MOSFET based level shifters as shown here:https://www.hobbytronics.co.uk/mosfet-voltage-level-converter

author: Renate
author_rank: Super Contributor
timestamp: September 07, 2021, 12:11:05 pm
content: The level shifting is easy.This is low speed, you could even just use a resistor divider.Or, if you like to live dangerously, just a resistor and hope that the protection diodes work!That stuff looks like infrared remote control baseband signal with that 3:1.It's not at great speed, but I don't really like having a user mode module decoding it off GPIO pins.Me? I'd stick it into an Arduino mini and have that spit out serial to the RPi.You could also rewire all the switches in that control unit and have the Arduino or the RPi scan it.

author: byoder
author_rank: Newbie
timestamp: September 13, 2021, 06:01:45 pm
content: Your observation that it looks like IR set me down the straight and narrow. I hooked it up to a gpio pin using a resistor divider, enabled the Pi's built in IR support in /boot/config.txt and used ir-keytable to map the scan codes to the desired keycodes. I've only done a bit of python scripting so decoding everything from scratch seemed daunting.

author: Renate
author_rank: Super Contributor
timestamp: September 13, 2021, 09:18:15 pm
content: Wow, that worked out great.It's much better to have a built-in driver handle it.
How to read a BIOS in an EPROM 29EE10 ? - Page 1
Forum section: electronics / beginners

author: air_america
author_rank: Newbie
timestamp: April 09, 2019, 11:57:56 am
content: Good morning to all of you.Can you help me ?I need to read (only read, not write) a BIOS of a old 486 mainboard .I just want to see the hexadecimal and ASCII codes .Is there any software (even in DOS ) to do this?I wouldn't want to buy an EPROM programmer just to read.The EPROM is a 29EE010 PLCC32.Thank you all.

author: CJay
author_rank: Super Contributor
timestamp: April 09, 2019, 12:00:50 pm
content: Quote from: air_america on April 09, 2019, 11:57:56 amYou may be able to find an old network card you can plug it into, there's software that will read the contents but I think you should be able to do it with debug from a command line if you only want to see the contents

author: air_america
author_rank: Newbie
timestamp: April 09, 2019, 12:38:27 pm
content: Thank you CJay.

author: CJay
author_rank: Super Contributor
timestamp: April 09, 2019, 02:08:53 pm
content: You may find that the BIOS is compressed and there is little in the way of legible text, but you should be able to see fragments

author: johnkenyon
author_rank: Regular Contributor
timestamp: April 09, 2019, 02:48:25 pm
content: My suggestion:Find a network card with a PLCC socket, install in your PCFind the software you need to enable the socket and/or define where it appears in the memory map. (Probably requires a boot into MSDOS).Install the device in the network card socket, reinstall the card.Boot the PC into MS-DOS with some form of writeable storage (floppy drive, small hard drive with FAT16 2.1Gb partition).Use the instructions athttp://mess.redump.net/dumping/dump_bios_using_debugto find and dump your ROM image.Note that a 29EE00 is a 128k x 8 device, and some network cards may not support 128k boot roms.The other alternative is to look for an EPROM reader - either use an old PC with a parallel port and something like the EPROMr (without the Vpp generation), or search for an Arduino based solution.Note that I haven't done this myself - I have an EPROM programmer, and a PLCC32 to DIP adaptor.If I didn't have that available, and the "put the device in a network card failed", I'd build myself a reader using an Arduino with a couple of counters to generate the address bits. (something like:https://www.element14.com/community/blogs/SalsCorner/2015/07/27/eprom-reader-project)PS. I assume you've got the device datasheet athttps://www.eit.lth.se/fileadmin/eit/courses/edi021/datablad/Memory/Eeprom/29ee010.pdf
How to read a DAC data sheet? - Page 1
Forum section: electronics / beginners

author: waspinator
author_rank: Contributor
timestamp: January 30, 2015, 11:28:22 pm
content: I'm want to try to make a simple arbitrary waveform generator as a project to learn more about electronics.I'm thinking of using a DAC controlled by a micro controller, but I'm not sure what to look for. For example when I look at the specs for a real AWG I always see the maximum frequency of a sin wave mentioned, but I'm not sure how I would translate that into a spec on a DAC datasheet.What are the most important specs to look for in a DAC for a project like this?ThanksExample DAC datasheet:datasheets.maximintegrated.com/en/ds/MAX541-MAX542.pdf

author: suicidaleggroll
author_rank: Super Contributor
timestamp: January 30, 2015, 11:45:02 pm
content: Well the biggest one with that device is going to be the serial clock. It runs at 10 MHz and requires 16 bits of data plus a CS cycle to latch it. So you're looking at around 18 clock cycles minimum per value. At 10 MHz, that means you can send the DAC one value every 1.8uS. It would take two values to make a square wave, so your fastest square wave could be ~275 kHz, but it's not going to be very clean and you're not going to have good frequency control up there. Realistically I'd say you'd be limited to ~25 kHz max, if you can handle only having ~10 discrete points per period in your wave (anything other than a square wave is going to be pretty ugly without some filtering).16 bit doesn't buy you much for that application, it just takes too long to get the data into the DAC to be of much use for high frequencies. You'd be much better off with a DAC that has less resolution and a faster clock (even half the resolution with the same clock would buy you double the frequency range since you'd be able to clock in your values twice as fast).Think about it this way. 16 bit has 65536 possible values. At 18 clock cycles per value and a 10 MHz clock, it would take you over 100ms just to sweep through the DAC's range once, in one direction.Setting time matters as well, but for that device in that application, the limiting factor is going to be how quickly you can pump the data into the DAC over that serial line.

author: dannyf
author_rank: Super Contributor
timestamp: January 31, 2015, 01:31:49 am
content: Quote
How to read an application diagram? - Page 1
Forum section: electronics / beginners

author: Posh
author_rank: Contributor
timestamp: January 14, 2015, 11:55:49 am
content: Hi guys, I am currently working on a 3-phase brush-less DC electronic speed controller and as such have been reading alot of datasheets.What I do not understand is the application diagram of the FAN7888 3 half-bridge gate driver, as seen in thisdatasheet.How do I know what value resistors, capacitors and diodes need to be used? (for example on the Vband Vslines)There appears to be no direct explanation on the datasheet, so am I meant to work out what resistors, capacitors and diodes to use from the information given about each pin? I am aware of both the functions of these components and basic electrical formulae. I just want to know if I'm reading the sheet right or missing something.Thanks.

author: amyk
author_rank: Super Contributor
timestamp: January 14, 2015, 03:09:53 pm
content: Look at these associated application notes:https://www.fairchildsemi.com/application-notes/AN/AN-9052.pdfhttps://www.fairchildsemi.com/application-notes/AN/AN-6076.pdf

author: Posh
author_rank: Contributor
timestamp: January 14, 2015, 10:48:54 pm
content: Thanks a lot! For future knowledge how can I find these relevent documents from simply looking up a part number?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 15, 2015, 03:53:19 am
content: If they aren't referenced in the datasheet, try going to the manufacturer's website and finding the part's main page.Tim

author: amyk
author_rank: Super Contributor
timestamp: January 15, 2015, 03:43:40 pm
content: Quote from: T3sl4co1l on January 15, 2015, 03:53:19 amThat'swhere I found them too.

author: Posh
author_rank: Contributor
timestamp: January 16, 2015, 07:25:03 am
content: Thanks for the info once again. I will go through the resources tonight.
[Answered] How to read an IC pin that switches between three states. - Page 1
Forum section: electronics / beginners

author: FlakeyCrust
author_rank: Newbie
timestamp: June 06, 2021, 02:45:16 am
content: I'm trying to design a circuit with a battery charging IC. It has a pin to communicate charging status with three states, but I'm not sure I understand one of them.The IC is LTC4006. The pin is labelled CHG and is described as follows:QuoteAnd here is the relevant portion of the IC block diagram:[I can't get inline attachments to work, see image 1]The state I'm not sure about is the one with the 25μA current. Does that mean it acts like it's connected to both ground and the positive end of a 25μA power supply (or more like a current limiter, since I supply the power)?Regardless, I just want to have an LED that is on when a battery is being charged, and off otherwise. Would this circuit do the trick?[I can't get inline attachments to work, see image 2]

author: bdunham7
author_rank: Super Contributor
timestamp: June 06, 2021, 03:40:44 am
content: Yes, the intermediate state would simply limit the incoming current to 25uA. In your circuit, you would have 60uA (12/200K) of base current in the full-on state, 25uA of base current in the low-charge state and less than 1uA (LED off) in the non-charging state. So unless you use a Darlington transistor, your LED will probably have three states--dim, dimmer and off.
How to read battey discharge mode - Page 1
Forum section: electronics / beginners

author: Syafiq Hamizan
author_rank: Newbie
timestamp: February 10, 2019, 02:38:52 pm
content: Hi All,I'm still new for this battery field. Currently I'm trying to source out lithium battery type for one of my project. One of my possible supplier provide a technical information request form as I need to fill it up. However, I have no clue on required details called 'discharge mode'. Attached is example of battery spec that I found online. Please advise me based on given battery technical spec. I just want to understand how to fill in the form based given spec attached. Based on attached battery specification, please help me how to fill in discharge mode details in a form 'technical information required'.Thanks in advanced.

author: Simon
author_rank: Unknown
timestamp: February 10, 2019, 03:32:23 pm
content: The discharge questions are quite simple, what are you trying to power. I see that the spec does not ask what capacity you desire so it looks like they are trying to work that out for you. The best thing is for you to tell them the capacity you require and the peak output current required and they should understand that.

author: rstofer
author_rank: Super Contributor
timestamp: February 11, 2019, 02:07:00 am
content: They allow for background current and pulse current. Perhaps you have a uC that sleeps most of the time and wakes up to check for <whatever>. Their will be some small current keeping the uC alive and a much higher current when it has to solve world hunger. What they're asking for is the nature of the background and peak loads.It's all shown in the picture. Just figure out what you project needs and fill in the blanks. But you have to tell them what your load imposes on the battery, they can't just guess!
How to read coil transformer encodings - Page 1
Forum section: electronics / beginners

author: Unknown
author_rank: Unknown
timestamp: April 27, 2014, 09:49:30 am
content: Hi,have some coil transformers from ATX power supply. Would like to know their muscles but all what I see are some numbers/letters. Could not find info on google, maybe searching for wrong keywords. Examples:309-35119-220 V: D631 Hi-POT OK308-16136-220 V:C631308-19113-220 V:6633thanks a lot

author: SeanB
author_rank: Super Contributor
timestamp: April 27, 2014, 10:28:04 am
content: Those are house codes from whichever Chinese company that wound them to order for the OEM of the power supply. You are not really likely to find out any info, and really you will find it hard to either reuse for another purpose or even take them apart without breaking them. Typically you will have a primary winding of a few turns, possibly 2 feedback windings and then a shield and a set of secondary windings.