hybridfree/eevblog-posts huggingface dataset:
R S T,L1 L2 L3, U V W - Page 1
Forum section: electronics / beginners

author: Simon123
author_rank: Regular Contributor
timestamp: March 28, 2014, 01:24:14 pm
content: Hello!I want to know, what RST in three phase system means?Is it short for some words or something?Thanks!

author: madires
author_rank: Super Contributor
timestamp: March 28, 2014, 01:50:09 pm
content: R-S-T is an old German naming convention for L1-L2-L3. It's not any abbreviation, just three consecutive letters. On some 3-phase motors you might also find U-V-W and X-Y-Z for the coils.

author: Simon123
author_rank: Regular Contributor
timestamp: March 28, 2014, 02:02:12 pm
content: Thanks madires.

author: deth502
author_rank: Frequent Contributor
timestamp: March 28, 2014, 08:37:17 pm
content: yup, just arbitrary consecutive letters, just like naming them A-B-C

author: Rory
author_rank: Frequent Contributor
timestamp: March 28, 2014, 10:24:38 pm
content: Did you even bother doing a Google search before asking here?

author: kingoftaurus
author_rank: Contributor
timestamp: March 29, 2014, 02:01:32 am
content: Sometimes a human response is better.

author: Kryoclasm
author_rank: Regular Contributor
timestamp: March 29, 2014, 04:16:55 am
content: R S T L N E I'll take V W and a U Pat.T _ R E E _ _ _ S E _ _ T _ R.

author: kingoftaurus
author_rank: Contributor
timestamp: March 29, 2014, 06:44:31 am
content: Quote from: Kryoclasm on March 29, 2014, 04:16:55 amI'd like to solve "Three Phase Motor"

author: AKM
author_rank: Contributor
timestamp: November 05, 2020, 07:55:53 pm
content: It means Reference (phase), secondary (phase) and tetriary (phase) in French.

author: nightfire
author_rank: Frequent Contributor
timestamp: November 05, 2020, 09:50:23 pm
content: Also in old systems (pre-1975) to be found is some old color coding: Yellow (L1), Green (L2) and Violet (L3), sometimes still used in high voltage installments.In those old systems black and/or grey was the PE...

author: Electro Fan
author_rank: Super Contributor
timestamp: November 05, 2020, 10:17:50 pm
content: Quote from: AKM on November 05, 2020, 07:55:53 pmIs there a reference link for this definition? Thx

author: Kjelt
author_rank: Super Contributor
timestamp: November 05, 2020, 10:42:24 pm
content: Not sure about this but I recall and checked that one of the first inventors of AC current, Galileo Ferraris named the primary vector R, in his 1888 paper, probably after Rotazioni (Rotation).Since I can not read Italian perhaps one of our Italian forum members would be kind enough to check.If it was just a sequence of random characters they could have started with A,B,Chttp://ieeemilestones.ethw.org/images/a/a0/1-Galileo_Ferraris_Rotating-field--Rotazioni_Elettrodinamiche.pdfEdit: Or perhaps R is the standard mathematical name for a Rotation vector, a Euclidean vector whose direction is that of the axis of a rotation and magnitude is the angle of the rotation.Perhaps someone can confirm this ?
R5F212L4SNFP clock settings register - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: August 17, 2016, 07:40:48 am
content: 1. I have written code for using on chip high speed oscillator for R5F212L4SNFP MCU for maximum 20Mhz speed.Is below settings & sequence ok?2. How many nop to be added to get clock stable. currently I have added 4.Code:void set_system_clock(void){/* Interrupt disable */asm("FCLR I");/* Protect off */prc0 = 1;/* cpu settings */cm02 = 0; /* Peripheral function clock does not stop in wait mode */cm05 = 1; /* XIN clock stops */cm06 = 0; /* CM16, CM17 enabled */cm10 = 0; /* Clock operates */cm11 = 1; /* On-chip feedback resistor disabled */cm13 = 0; /* Input ports P4_6, P4_7 */cm14 = 0; /* Low -speed on-chip oscillator on */cm15 = 1; /* XIN-XOUT drive capacity high */cm16 = 0; /* System clock division select bits; no division */cm17 = 0; /* System clock division select bits; no division */ocd0 = 0; /* Oscillation stop detection function disabled */ocd1 = 0; /* Oscillation stop detection interrupt disable */ocd2 = 1; /* Selects on-chip oscillator clock */ocd3 = 1; /* XIN clock stops */fra00 = 1; /* High-speed on-chip oscillator on */fra01 = 1; /* Selects high-speed on-chip oscillator */fra20 = 0; /* High-speed on-chip oscillator frequency sw itching bits, Divide-by-2 mode */fra21 = 0; /* High-speed on-chip oscillator frequency sw itching bits, Divide-by-2 mode */fra22 = 0; /* High-speed on-chip oscillator frequency sw itching bits, Divide-by-2 mode *//* let clock get stable */asm ( "nop" );asm ( "nop" );asm ( "nop" );asm ( "nop" );/* Protect on */prc0 = 0;/* Interrupt enabled */asm("FSET I");} /* functin ends here */
racal 9903 - Page 1
Forum section: electronics / beginners

author: ME
author_rank: Frequent Contributor
timestamp: March 08, 2025, 02:00:07 am
content: Does anyone know what the max freq a Racal 9903 counter timer can measure?,thanks.

author: Gyro
author_rank: Super Contributor
timestamp: March 08, 2025, 09:38:50 am
content: https://www.google.co.uk/search?q=racal%209903%20specification

author: ME
author_rank: Frequent Contributor
timestamp: March 08, 2025, 02:53:11 pm
content: the link doesent list a 9903 as far as i see .

author: Stray Electron
author_rank: Super Contributor
timestamp: March 08, 2025, 03:13:09 pm
content: Description:9903DISCONTINUED BY MANUFACTURERUNIVERSAL COUNTER TIMER10-50MHZ223-251 VA.C45-450HZ OPERATIONFACTORY WARRANTY MAY NOT APPLY. RADWELL 2-YEAR WARRANTY INCLUDEDPosted herehttps://image360.radwell.com/Buy/THALES%20COMMUNICATIONS/RACAL/9903

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: March 09, 2025, 07:53:47 am
content: If you are looking for a counter mainly for frequency counting, as opposed to timing between inputs, for not much more money the 9915 or 9916, etc go to much higher frequencies. I had a 9915 at work and used to own a 9916 (both are 10 Hz to 520 MHz) before replacing it with a 1998 (10 Hz to 1300 MHz).SJ

author: 807
author_rank: Frequent Contributor
timestamp: March 11, 2025, 01:12:32 pm
content: Quote from: Stray Electron on March 08, 2025, 03:13:09 pmTo be clear, that's 10Hzto 50MHz.
RACAL DANA 9232 DP - Page 1
Forum section: electronics / beginners

author: kardacz
author_rank: Contributor
timestamp: July 11, 2015, 08:37:51 am
content: Hello; I have a laboratory power supply RACAL DANA 9232 DP down. At start it shows: FAULT 41 and 42 of the 2 outputs. Someone would he you an idea ?? Or better: there you have the diagram ?? Thanks for your help

author: Andy Watson
author_rank: Super Contributor
timestamp: July 11, 2015, 08:48:40 am
content: Those Racal power supplies are re-badged Thurlby Thandar / TTI units. I believe that model is the equivalent of a Thurlby PL320.

author: kardacz
author_rank: Contributor
timestamp: July 11, 2015, 09:05:45 am
content: Alas, this model does not match mine, because it is a programmable power supply .....

author: Andy Watson
author_rank: Super Contributor
timestamp: July 11, 2015, 02:41:42 pm
content: Thurlby's "PL" range covers many models from manual single output to triple output programmable units.

author: Psi
author_rank: Super Contributor
timestamp: July 11, 2015, 03:06:38 pm
content: Why does this need a pointless poll?

author: kardacz
author_rank: Contributor
timestamp: July 12, 2015, 07:44:41 am
content: Hello; I find neither equivalent nor the scheme ......

author: miguelvp
author_rank: Super Contributor
timestamp: July 12, 2015, 01:30:56 pm
content: I know you already said that the thurlby PL320 doesn't match yours, but if you want to take a peek look at the PL Series Power Supply pdf in this wayback machine link, since the original site no longer has it or it's gone.http://web.archive.org/web/20140408212724/http://k1.dyndns.org/Vintage/Sinclair/Other%20Inventions/Other%20Electronics%20Products/

author: kardacz
author_rank: Contributor
timestamp: July 12, 2015, 04:01:43 pm
content: alas; no schema matching; L-132 not!

author: Andy Watson
author_rank: Super Contributor
timestamp: July 12, 2015, 04:20:20 pm
content: Could you post a photo?

author: kardacz
author_rank: Contributor
timestamp: July 13, 2015, 10:51:24 am
content: how to put a picture there

author: Muxr
author_rank: Super Contributor
timestamp: July 13, 2015, 05:15:38 pm
content: I voted on the last HELP that wasn't voted on!

author: kardacz
author_rank: Contributor
timestamp: August 16, 2015, 07:56:18 am
content: Here image; could someone help me

author: kardacz
author_rank: Contributor
timestamp: August 16, 2015, 07:59:54 am
content: this site is weird; you can not insert a picture !!

author: miguelvp
author_rank: Super Contributor
timestamp: August 16, 2015, 08:11:43 am
content: @kardacz click under "attachements and other options" when you reply.The file has to be one of the following extensions: doc, gif, jpg, pdf, png, txt, zip, tar, c, h, hex, bas, xls, odt, asm, wav, aiff, wma, mp3, flacyou can only put up to 25 per post for a maximum total size of 2000KB. and a single file can't be over 1000KB.Once you are able to attach it, there are ways to make a link to the attached image, but we can get there once you are able to attach the image.
Radar System Cradle Relay - Page 1
Forum section: electronics / beginners

author: LATECH-EE
author_rank: Newbie
timestamp: August 20, 2013, 04:05:58 pm
content: Hey everyone, I am a radar systems technician for the US Air Force and I work on a radar from Raytheon called the D.A.S.R. I recently had a 10 Amp relay burn up due to an internal short in the system. I was curious if anyone here knew what the red grease-type material is on the electromagnet's outer lamination. I thought electromagnets did not have any grease inside of them. I was just curious in general, thanks guys!

author: dr.diesel
author_rank: Super Contributor
timestamp: August 20, 2013, 04:11:12 pm
content: Probably just the enamel off the magnet wire.Is it really soft like grease or fairly hard?

author: SeanB
author_rank: Super Contributor
timestamp: August 21, 2013, 04:42:15 am
content: It could have been wax impregnated after winding for extra environmental protection, which with the heat of the relay being shorted out ( probably the coil was operated with a too high voltage or it was duty cycle limited and operated at 100% for an extended period) reacted with the insulation to make this grease like substance.If not impregnated then it was the result of the wire enamel being cooked without enough oxygen to burn it, making an organic compound that looks like foam.

author: KJDS
author_rank: Super Contributor
timestamp: August 21, 2013, 06:23:45 am
content: It looks like jam freshly dripped from a doughnut.

author: Skimask
author_rank: Super Contributor
timestamp: August 21, 2013, 06:54:51 am
content: Well, of course it's jam.The radar was jammed!

author: ddavidebor
author_rank: Super Contributor
timestamp: August 21, 2013, 08:47:57 am
content: That connection point look very goldish! Stole it stole it :-)
Radial bus at low baud rates - Page 1
Forum section: electronics / beginners

author: e100
author_rank: Frequent Contributor
timestamp: December 14, 2016, 08:23:08 am
content: Thinking of abusing the CAN bus spec to create a star network for home automation.The slew rate of a CAN bus transceiver such as the TI HVD230 can be set to a max of 160 ns which allows unterminated radial stubs of up to 5 meters.Seehttp://www.ti.com/lit/an/slla270/slla270.pdfHow to lower it even more so I can run run longer stubs at very low baud rates such as 1200 bps?Can I add series resistors like they do with USB, then adjust the 60 ohm termination resistor at the hub?The chip makers application notes don't talk about baud rates or signal integrity below 50k.Mike

author: e100
author_rank: Frequent Contributor
timestamp: December 18, 2016, 08:01:05 am
content: Hmm, no responses, that that indicate that this idea is impractical, won't work or is unlike anything anyone has ever done before?I know that the phone line to my house has a number of unterminated radial branches that go off to several rooms and it still works OK, at least in the < 5 kHz range.Mike

author: SeanB
author_rank: Super Contributor
timestamp: December 18, 2016, 09:18:58 am
content: Sounds like an ideal use for the venerable RS422 bus, just use either 2 twisted pairs, with one providing a ground reference, as you really want to keep in the middle of the CMRR of the differential receivers. Or use a microprocessor at the ends that has an ethernet PHY in it ( 10/100M will be fine, and ultra cheap from the switch side) and POE for the system, using a central POE switch to power them.That way you have both easy connection ( cheap cables and connectors) and with ethernet and POE you have some power at the nodes, at least enough to power sensors and such, even small displays and perhaps even small low power actuators, without needing power cabling.Even going RS422 use cheap Cat5 cabling and connections, so you have redundant pairs and can transfer power down the spare pairs as well, if you can live with the cable loss.

author: magetoo
author_rank: Frequent Contributor
timestamp: December 18, 2016, 01:12:13 pm
content: Could one perhaps use multiple transceivers, diode-ORed together, to create a sort of repeater/hub for multiple segments? That way each segment could be done according to spec electrically.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 18, 2016, 08:58:35 pm
content: You can put RC or LC filters on the devices, to slow down their edge rate. Make sure the receivers are okay with that, and don't use more than e.g. the system ACK delay, or baud rate, can withstand.This also increases immunity to RFI and EMI.CAN has higher immunity than RS-485, though the latter is probably more easily filtered due to its simple design. Isolated adapters aren't uncommon for both, though beware if they have low capacitance isolation as well.Tim
Radio: 1946 Gilfillan 56B - Page 1
Forum section: electronics / beginners

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: December 06, 2023, 02:55:02 pm
content: Last week, I had the pleasure of receiving this 1946 Gilfillan 56B radio. When I met the individual selling the radio, I asked him how he came to be the owner of it. He said, "I purchased it new when I was in high school". Wow. The original owner of the radio!Although, he said that it turns on and works fine, I am not going to do so just yet. I know it needs to be recapped but I might bring it up on the variac just before starting that effort.I need to finish up a radio I am already working on before starting this one but I'm certainly looking forward to cracking this one open.Thank you,- Wil

author: xrunner
author_rank: Super Contributor
timestamp: December 06, 2023, 03:06:31 pm
content: Oh I love that AC plug!

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: December 06, 2023, 03:40:47 pm
content: You might wish to ask the seller for a letter documenting when and where he bought it.In the unlikely event he kept the receipt, that might be valuable also.

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: December 06, 2023, 04:15:57 pm
content: Quote from: Wallace Gasiewicz on December 06, 2023, 03:40:47 pmHe doesn't remember. The only "somewhat" reliable information I could get from him was that he "thinks" he bought it while he was in high school. Maybe it was different back in ~1960-ish but was a radio that was made in 1946 still sold new in the 60s?! It seems strange to me when I do the math.As for the receipt, I would imagine that he if were the kind of person who would actually keep a receipt for ~62 years, he would also be the kind of person who wouldn't be getting rid of the radio itself.- Wil

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: December 06, 2023, 04:17:34 pm
content: Quote from: xrunner on December 06, 2023, 03:06:31 pmI do too... which is why I took that photo. It fits really good in the hand and I've never seen one like this before. It will definitely NOT be removed... but it will probably see a new cord.- Wil

author: TimFox
author_rank: Super Contributor
timestamp: December 06, 2023, 05:25:19 pm
content: Here's my favorite contemporary US small-appliance plug, supplied with a good toaster.I don't know why finger holes such as this one and your old one are so uncommon.(I definitely recommend replacing the "zip cord" on a radio as old as yours.)

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: December 06, 2023, 06:37:38 pm
content: Quote from: TimFox on December 06, 2023, 05:25:19 pmOoh... that's a cool-looking plug.
Radio Frequency Close connection - Page 1
Forum section: electronics / beginners

author: dleebell
author_rank: Contributor
timestamp: April 02, 2015, 04:48:00 pm
content: HiI've got a project, where I'm using a one way Radio frequency system between 2 devices (Similar like a baby monitor).At certain points of using the 2 devices they will be together, so touching physically side by side. I know with walkie talkies if you put them close together they create noise.I have two concerns:Are they still able to send information to each other without interference of one another?Are you able to get rid of the noise interference by disconnecting the speaker on one of the devices without affecting the information that is sent from the frequency waves?Or is there an easier way of getting rid of this noise without affecting the information being transmitted from one to the other.Many ThanksDominic

author: w2aew
author_rank: Super Contributor
timestamp: April 02, 2015, 06:04:58 pm
content: There are two main problems that arise (and a host of others) with a transmitter and receiver placed close together.The "noise" you mentioned when placing walkie talkies together is due to simple audio feedback - an audio signal from the speaker on the receiver being picked up by the transmitter's microphone - resulting in some "positive" feedback which results in howling or squealing most often. For this scenario, disconnecting the speaker or muting the receiver will usually stop the interference.The second most common effect is overload of the receiver which happens if the receiver and it's front end, AGC, etc. are not designed for the high signal strength that occurs when the receiver's antenna is so close to the transmitter, thus coupling a very high signal level into the receiver. The only way to combat this is to reduce the coupling between the devices (shielding the antennas from one another, removing the receive antenna, dropping the tx power, etc.).The other things that can happen can be more complex, with things like the transmit signal begin coupled into the LO and IF stages in the receiver, etc. The extent and side effects of this type of thing will vary greatly with the design and function of the devices being used.

author: dleebell
author_rank: Contributor
timestamp: April 02, 2015, 06:26:49 pm
content: Hi w2aewMany thanks for your reply.QuoteOk so because the neither of the two devices that I have microphones they only have speakers, does this mean I won't have any interference?Quote1. shielding the antennas from each other: would this make this more difficult to send information to one another?2. Removing the receiving antenna: Does this mean it can still recieve information from the transmitting device? In this case can it be that theres a switch to disconnect it?My basic design, is one device with buttons (Each with a different tone frequency) that transmits information to the receiving device which in toll processes it and plays it on that device.Many Thanks for your help again.Dom
Radio - input signal strength and Cu Cpi values ? - Page 1
Forum section: electronics / beginners

author: MathWizard
author_rank: Super Contributor
timestamp: October 27, 2021, 05:27:41 pm
content: When modeling a radio in LTspice, what is a reasonable signal voltage and source impedance for a little ferrite coil antenna like in a little AM receiver ?Also what are some typical values of Cu and Cpi for a 2n3904 or similar , I read both may be a few pF? I see at AM freq. they have huge Xc tho. I was trying to calculate them last week from the spice param's but ran into trouble, I'll try another time.
Radio Module Problem  - Page 1
Forum section: electronics / beginners

author: abdullahseba
author_rank: Frequent Contributor
timestamp: February 04, 2015, 12:00:43 pm
content: can any one tell me what this means? In the datasheet attached it says on page 5 it said that pin 7 was not to be connected to a VDD or high level of CMOS output. Does that mean you cannot connect it directly to a micro-controller or does it mean something else?

author: AndyC_772
author_rank: Super Contributor
timestamp: February 04, 2015, 12:06:47 pm
content: It probably means it's a logic input for which logic '1' is a lower voltage than the supply voltage for the module, and which would be damaged if the full supply voltage were to be applied.If you can configure a microcontroller pin to always either output a logic '0' or be a high impedance input (without pull-up or pull-down), then that would probably work OK. There's a risk, though, that you don't always know what the pin will do during power-up or down, or during programming, or in the time in between being powered up and reaching the part of your code which configures it.The safe thing to do is to use an external FET, like, say, a 2N7002, to pull the pin to GND, and to drive the gate of that FET with the microcontroller's output. You then just need to configure the MCU pin as an output, and nothing it does can cause the pin of the radio module to be driven high.

author: abdullahseba
author_rank: Frequent Contributor
timestamp: February 04, 2015, 12:09:52 pm
content: Quote from: AndyC_772 on February 04, 2015, 12:06:47 pmThanks
Radio Shack Semiconductor Reference Guide - Page 1
Forum section: electronics / beginners

author: watchmaker
author_rank: Unknown
timestamp: November 09, 2023, 08:37:08 am
content: My 6 pound grab box consisted primarily of RS semiconductors still on their hang cards from the closeout. The pack referred to the RS Semi Reference Guide. Multile years are available on the Internet Archive.Spent a couple hours going through it; I have at least one of everything so it will be useful.But I learned several things. The prefix, (2N, LM, MPS) is simply the manufacturer code. Never knew that. Then, it seems RS felt the vast selection of transistors could be reduced to a couple dozen numbers that likely satisfied 90% of demand. Makes life simpler for the likes of me.It also contains an excellent glossary and drawings of many case styles that may not be seen today. For example, the A3 diode package was used to build high power bridge rectifiers before prepackaged bridge ckts.Not so useful today, but it does also show application ckts for many of the devices. Like a dial tone demodulator! Gotta figure out other uses for those, I got 8.

author: SuzyC
author_rank: Frequent Contributor
timestamp: November 09, 2023, 03:12:14 pm
content: The "2N" is not just one mfg's code. It is a generic JEDEC registered name for a transistor made by many different mfgs.Example: 2N2222

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: November 09, 2023, 11:50:50 pm
content: I have seen many poor choices done by subsitution manuals including the japanise sub manual.I have found it better to make my own choices many times.BUT, they can be a great source of information just do not follow blindly.Jeff

author: Stray Electron
author_rank: Super Contributor
timestamp: November 10, 2023, 12:10:47 am
content: The other problem with generic replacement parts as recommended by RS and others is that they don't always have the same pinout as the part that you're replacing so do your homework before blindly replacing a part.
Radio  Spares Legacy datasheets - Page 1
Forum section: electronics / beginners

author: Mechanoid69
author_rank: Newbie
timestamp: September 07, 2025, 05:22:04 pm
content: I have inherited a quantity of very old components, some from the 1960's. There are also a quantity of components marked with just an RS part number. I have tried to identify some of them but because they are obsolete, the only reference I can find is to look at the RS archived datasheets. Does anyone know where there would be a search and download site for datasheets from this archive or how to get access to it?Thanks.

author: Andy Watson
author_rank: Super Contributor
timestamp: September 07, 2025, 09:09:10 pm
content: I have been looking for the old "RS Data Library" too. I used to have the three-volume set of datasheets in the ring-binders, but they went in the bin when the internet happenedOops!Somebody somewhere must have scanned them!

author: tggzzz
author_rank: Super Contributor
timestamp: September 07, 2025, 10:32:54 pm
content: Back then Radiospares branded components were things to avoid: they took the scrag end of whatever the manufacturer produced.A classic case was 741 opamps. Instead of the input offset voltage being a symmetrical normal distribution around 0mV, it was bimodal near +13mv and -13mV; the limit was 15mV(Numbers invented to clarify the principle)

author: fzabkar
author_rank: Super Contributor
timestamp: September 07, 2025, 10:52:35 pm
content: I have a 1990 RS catalogue.

author: Ian.M
author_rank: Super Contributor
timestamp: September 08, 2025, 05:39:38 am
content: The July 1985 edition of the "RS Data Library"can be found here:https://groups.io/g/ManualExchange/topic/36422570#msg13061The mediafire links appear to still be good - I'm downloading the first as I type this.Edit: It downloaded and opens OK.Thanks for posting its title - I've got some RS parts from the '80s but unfortunately only got a few photocopies of stuff I was then interested in from the long-retired tech I knew in the early '90s with the RS data library + other data book collection. I unfortunately lost touch, but he can't still be with us - it would be world news if he was! Most old RS part numbers are basically unsearchable on the WWW as they have been reused for something completely different@All: Don't discard data books till you have confirmed they are preserved online at a reputable archive!

author: Gyro
author_rank: Super Contributor
timestamp: September 08, 2025, 07:21:24 pm
content: The optimized 92MB version is still quite readable and quicker to open.

author: Ian.M
author_rank: Super Contributor
timestamp: September 09, 2025, 07:19:10 am
content: Yes, I grabbed that as well for convenience, but its good to have the hi-rez 'raw scan' version in case any of the diagrams failed to compress well.
radio transmitter circuit - Page 1
Forum section: electronics / beginners

author: yalect
author_rank: Regular Contributor
timestamp: May 19, 2015, 07:31:34 am
content: Hello,I would like to ask you if I can send data with simple radio, circuit transistors and op-amp, is there a circuit (transmitter and receiver)?Thank you

author: Simon
author_rank: Unknown
timestamp: May 19, 2015, 07:39:59 am
content: you can buy off the shelf modules to receive and transmit, I think they work on something like 440MHz. an FM trasmitter is relatively easy to make and there are lots of diagrams online but you would need a radio to decode it again. What sort of data are you trying to transmit ?

author: jeroen79
author_rank: Frequent Contributor
timestamp: May 19, 2015, 10:44:06 am
content: There are several off the shelf options.433MHz modules, wifi, bluetooth and GSM/3G/4G are all radio.Building your own transmitter/is also possible. Lots of schematics can be found online.But do you want exactly?Over what distance do you want to communicate?What sort of data and how much?If you want to build something yourself then you should look into your country's regulations regarding radio.There may be restrictions and you may need a license.

author: yalect
author_rank: Regular Contributor
timestamp: May 19, 2015, 07:38:38 pm
content: Hello,thank you for your replymy circuit is just for getting the base of working such circuits, I want to send binary data one or two regardless what they are, with important distance, some Amateurs use the frequency of 27Mhz and other high frequencies, I am looking for simple Ideas (transistor, Op-amp)thank you
Radio wave questions. - Page 1
Forum section: electronics / beginners

author: Jimbz
author_rank: Contributor
timestamp: June 25, 2014, 04:09:35 am
content: Greetings everybody, two questions popped out of my head regarding transmitting radio waves.1) In FM you add together a carrier wave (fixed frequency) and a signal, their sum is now a wave that has varied frequency ? But how will the receiver know the correct frequencies that it should pick up the transmitted waves ?2) How do you transmit DC ? As in DC modulated into carrier waves ?

author: Kremmen
author_rank: Super Contributor
timestamp: June 25, 2014, 05:10:58 am
content: In a nutshell (it is a bit more complext than this, but the idea is here):1) You have a local oscillator running at the "station frequency". From the amplified antenna signal you subtract the local frequency, leaving the modulation frequency as the result. That is further bandpass filtered and amplified to get the final audio signal. Varuing the local oscillator frequency tunes the stations.2) You have a static signal frequency offset from the nominal station "carrier" frequency. This is normally not practical however.

author: xwarp
author_rank: Frequent Contributor
timestamp: June 25, 2014, 08:14:47 am
content: Here;http://www.egr.msu.edu/~aviyente/AM-FM.pdf

author: rob77
author_rank: Super Contributor
timestamp: June 25, 2014, 09:08:39 am
content: a very simplified explanation of FM modulation - the carrier is swept by the input signal - 0 in the input signal corresponds to center frequency of the carrier. (actually it's more complex than that, but to understand the principle it's enough)

author: babysitter
author_rank: Frequent Contributor
timestamp: June 25, 2014, 05:44:20 pm
content: Its simple: You have a oscillator which you can de-tune with your modulation signal. If there is no modulation at all, just 0V, it will transmit only on a carrier frequency. your positive or negative part of the modulation signal pulls this transmitted frequency either up or down. The receiver needs to know the carrier frequency and uses e.g. filters to detect this variation.

author: katzohki
author_rank: Frequent Contributor
timestamp: June 25, 2014, 08:21:05 pm
content: I'll throw in my explanation of FM:Say you have a 10kHz sine wave that you want to transmit. And say you have a radio station 93.7 MHz. Ok, so your signal (you could call it a message) "modulates" the carrier (the 93.7 MHz base frequency) by shifting it in frequency at a rate of 10kHz (10000 times per second). The AMOUNT that the frequency varies is based on your "modulation index" which can be based on a standard for the type of communication.Here's a really bad wording: The FREQUENCY that the frequency varies is based on the frequency of the input signal (sorry).Demodulation is opposite of modulation.
Rail to rail opamp - Page 1
Forum section: electronics / beginners

author: semaphore
author_rank: Contributor
timestamp: September 13, 2010, 01:49:14 am
content: I need a very basic low cost rail to rail opamp for my projects. Can anyone recommend some? Prefer standard 8-PIN DIP with dual channel. Oh... the bandwidth is below 10KHz.

author: allanw
author_rank: Frequent Contributor
timestamp: September 13, 2010, 08:31:15 am
content: I'd go on Digikey and filter by rail-to-rail, DIP-8, then by quantity available. There should be plenty to meet your needs.
RAM Battery charger - Page 1
Forum section: electronics / beginners

author: The Good Dr
author_rank: Contributor
timestamp: January 02, 2013, 09:08:39 am
content: Hello does anyone know if its possible to charge standard alkaline batteries in a RAM (rechargeable alkaline manganese) charger?

author: IanB
author_rank: Super Contributor
timestamp: January 02, 2013, 09:54:35 am
content: Yes, it is possible. No, it is not a good idea.Alkaline batteries are prone to leaking even if used normally. If you try to recharge them the possibility of them spilling their guts everywhere is greatly increased. So the question is, how much do you value the equipment you plan to use these batteries in?Some of us have completely abandoned the use of alkaline batteries. As someone has as their tag line on another forum:"Friends don't let friends use alkaline batteries."Current rechargeable battery technology in the form of Sanyo eneloops or similar products has all but rendered the RAM battery obsolete. Eneloops will work in almost all applications of alkaline batteries, and crucially,they will not leak.For those odd occasions like clocks where you want to use a disposable battery there are Energizer lithium primary cells. The Energizer Advanced lithium has the same capacity as the Ultimate lithium for 2/3 price and as with the eneloops, they will not leak either.There is no need to risk leaky alkaline batteries in any of your devices these days.

author: Teemo
author_rank: Regular Contributor
timestamp: January 02, 2013, 10:17:54 am
content: Hello,I have AccuCell charger for alkaline betteries. I got this for free some years ago. It was interesting to play with alkaline batteries, yes they take charge. Unfortunately there are huge drawbacks for using recharged alkalines. They can only be charged if they are not completely empty. And recharged alkalines are VERY prone to leak. Some brands tend to leak more quickly, and they do not leak during charging, but after, when they are in use! This AccuCell charger was ment for their special alkaline rechargeable batteries. I did not have those of cource so I experimenterd with regular alkalines.But there is absolutely no practical point of really using recharged alkalines. They were nice to play with, but absolutely no practical value to me.

author: The Good Dr
author_rank: Contributor
timestamp: January 02, 2013, 06:20:42 pm
content: Thank you both for your opinion's and advice. I think I'll give recharging alkaline's a miss, it just seems such a waste as nearly all the kids toys this year are battery powered. I think I'll invest in a good set of rechargeable's. Many thanks, kind regards Edwin.
Ram & flash check operation - cortex m3 - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: December 21, 2014, 03:59:08 pm
content: Is there any need to do memory check in MCU before beginning operation?I had read on new MCU its not needed?is there any example code specific to cortex-m3?

author: Jeroen3
author_rank: Super Contributor
timestamp: December 21, 2014, 08:29:39 pm
content: There is no specific need to compare the flash contents to a checksum in normal applications.However, if you don't check it, you cannot assume the contents are correct after years of operations.Sram checksums are almost only used in automotive or high security/reliability applications. And this is usually done by the hardware itself.You can run a check to scan the sram for problems, but I've never heard of bad sram in micro's.SRAM and Flash are vulnerable to high energy emi pulses and ionizing radiation. Which are relatively rare apart from ESD, lightning and nuclear detonations.Anyway, flash checking is easy because ARM uses a single address space, you can just use a for loop.If you have a CRC perihperal, use it. Otherwise you might want to simplify the checksum by reducing it to an exclusive-or operation to save time.The only obstacle is getting the valid checksum into the binary image. You can either use the toolchain or your own tool to insert this.Or you reserve a flash page, have the linker fill this with a predefined pattern to state "empty", and write the checksum on the first time it is calculated and the flash page is empty.This will be soon after the programmer flashed and verified the binary, leaving little chance for data corruption.Assuming your chip support support self-programming.Only after you've compared it against the checksum you are allowed to say something about the correctness of the flash image. The percentage depends on the algorithm used.
ram question - Page 1
Forum section: electronics / beginners

author: p.larner
author_rank: Frequent Contributor
timestamp: December 21, 2023, 03:54:45 am
content: can PC3-12800R-11-13-E2 REGISTERED ECC ram be used in a gigabyte GA-78LMT-USB3 rev5 motherboard?

author: SuzyC
author_rank: Frequent Contributor
timestamp: December 21, 2023, 04:48:42 am
content: no, won't even fit in the socket, locating notch is different for ECC

author: mariush
author_rank: Super Contributor
timestamp: December 21, 2023, 05:43:41 am
content: It's the REGISTERED part that's a problem ... Unregistered ECC ram is the same as regular ram (unregistered ram) and will go in a regular ram slot but the ECC part may or may not be supported - traces have to exist between the slots and the socket, the memory controller inside cpu must support ECC (most do) and ECC must be supported and enabled in the bios.REGISTERED ram has an extra buffer chip on the stick, besides the extra ram chip used for holding the ECC data (error checking and correction) and regular desktop processors are not designed to support that extra buffer chip, so REGISTERED ram sticks won't work in socket AM3/AM3+/AM4/AM5 etc etc
Ramping a reference voltage up from, or down to  zero volts, over ~200us - Page 1
Forum section: electronics / beginners

author: ocset
author_rank: Super Contributor
timestamp: January 26, 2020, 08:12:24 pm
content: Hi,Please assist us in ramping a reference voltage down to zero volts, or back up to the reference voltage. This being done at random times, on demand. The ramp should be over some 200us. It should be linear, but its not too bad if its not that straight….it could even be say in 10 steps (up or down).The reference voltage could be any level from 0V to 0.5V.….So eg it could be at, say, 0.23V…and every now and again we would need to ramp it down to zero volts….then some time later, ramp it back up to 0.23V.Would you agree that the attached method is the best way?It just uses a microcontroller to PWM the buffered reference voltage…variable PWM to make it ramp over 200us (please ignore RC values in schem) …as discussed, it could be 10 steps, so 10 different duty cycles inside the 200us ramp time.Please confirm there are no nice analog modules which do this, and no nice sub circuits which can do it better than this?(I wasnt going to post, but thought this may be of interest to others...and i believe i have provided a solution, though unfortunately it uses a microcontroller)

author: rstofer
author_rank: Super Contributor
timestamp: January 26, 2020, 08:53:58 pm
content: How does VDS(ON) play into this? It isn't 0.000V - it might get down to 0.09V, give or take, but always greater than 0V. Maybe reaching absolute 0.000V isn't really necessary.If it doesn't matter how long the output is 0V and it doesn't matter how long it stays at the reference value and the primary consideration is the 200 us ramp, I would use a relay. That way I can get to 0V (given suitable gold plated bifurcated contacts).

author: ocset
author_rank: Super Contributor
timestamp: January 26, 2020, 09:20:40 pm
content: Thanks, actually the slight vds(sat) of say a 2N7002 NFET will be fine.Its basically a power supply which is getting switched in and out at certain times...and the reference needs to gradually ramp down (or up) in ~200us....but there's no real precision needed here.

author: ocset
author_rank: Super Contributor
timestamp: January 27, 2020, 09:07:38 am
content: HiActually, now i think 200us is too small a time for a micro to do the ramp….so I have done the attached circuit…however, it needs a +/-5v supply and the ramp is a little less linear than I’d like.(LTspice sim and pdf schem attached)Any improvements much appreciated.

author: David Hess
author_rank: Super Contributor
timestamp: January 27, 2020, 09:16:18 am
content: Pulse width modulation is not a bad way to do it. I would have used an analog switch but a 2N7000 should work also.A buffered RC filter is much simpler and the exponential waveform is usually sufficient. A very linear slew rate limiter can be made with current sources and a diode bridge.
Random PCB Layout? - Page 1
Forum section: electronics / beginners

author: nbritton
author_rank: Frequent Contributor
timestamp: October 16, 2015, 06:11:34 am
content: In the attached picture there is what appears to be randomly laid out components. It's a photo from the teardown of the Rigol DS4000. I doubt this is random, what exactly is going on here, why did they decide to lay it out like this?

author: tautech
author_rank: Super Contributor
timestamp: October 16, 2015, 06:52:29 am
content: More importantly, what are the unpopulated components?Model upgrade? Options?

author: amyk
author_rank: Super Contributor
timestamp: October 16, 2015, 08:32:33 am
content: It's high-frequency circuitry, with careful consideration of track length and parasitics. Get into the microwave range and things start looking even weirder...

author: SteveLy
author_rank: Regular Contributor
timestamp: October 16, 2015, 10:16:55 am
content: I love it! More circuit boards should be like this! Like a medieval Italian village instead of boring modern planned development.

author: Neilm
author_rank: Super Contributor
timestamp: October 16, 2015, 02:43:26 pm
content: I have done similar with high voltage circuits where I had large clearance and creepages to worry about.

author: nbritton
author_rank: Frequent Contributor
timestamp: October 16, 2015, 04:15:22 pm
content: Quote from: tautech on October 16, 2015, 06:52:29 amYeah I was wondering that myself since I just bought one of these. This was the DS4014 100 MHz model, the community has been able to hack them to 500 MHz, but these missing components have me quite concerned that something essential is missing.

author: JoeN
author_rank: Frequent Contributor
timestamp: October 17, 2015, 02:26:21 am
content: Quote from: nbritton on October 16, 2015, 04:15:22 pmSometimes it's the opposite and components are added to roll off the bandwidth. You got to remove those.

author: crispy_tofu
author_rank: Super Contributor
timestamp: October 17, 2015, 09:29:39 am
content: Wow, pretty funky. Almost as if someone forgot to route it! (j/k)

author: dmills
author_rank: Super Contributor
timestamp: October 17, 2015, 11:01:05 am
content: Look closely, it looks to me like there is a deliberate plane cutout out on all layers under that region, so stray capacitance was probably important to minimise in that area.Scope inputs are normally specified as 1M || 10pf, which means that minimising the input capacitance is quite critical, and they typically have about 5 decades of variable gain, this is the fun sort of analogue to design....Regards, Dan.

author: poorchava
author_rank: Super Contributor
timestamp: October 17, 2015, 11:26:09 am
content: The seemingly random placement is to reduce trace length so that lumped element model can be used. It's one of the ways to avoid or reduce keeping proper trace impedance. If the trace is long you usually need to treat it as a transmission line and use distributed element model for calculations. When trace is very short you may get away without it.Sent from my HTC One M8s using Tapatalk.
Random unknown ferrite bead calculation - Page 1
Forum section: electronics / beginners

author: RickieSalad
author_rank: Regular Contributor
timestamp: June 10, 2016, 05:23:18 pm
content: If someone was feeling particularly ambitious while cleaning and organizing their electronic components and wanted to determine the values of a bunch of random salvaged ferrite beads, is that possible? Is there a way to measure them, or is it more of a calculation based on sizes and shapes?I hope this isn't a stupid question.

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: June 10, 2016, 05:47:21 pm
content: My limited info is mostly related to RF ham radio .Toroids / ferrites come in many flavors , iron or ferrite , maybe starting with either power or RF , with RF having a larger variety or so-called mix's , each mix is frequency dependent .I guess that the need for IDing is mostly for RF uses , so putting a few turns of wire through & measuring is a start .A link or 2 to start ,http://www.cliftonlaboratories.com/estimating_q_of_ferrite_cores.htmcalculatorhttp://toroids.info/http://www.electronics-tutorials.com/basics/toroidcharts_mcq.htm

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 11, 2016, 01:58:32 am
content: 100MHz oscillator. Set it up as a voltage divider: osc output -- FB -- 50 ohm terminated cable (e.g. scope/speccy/RF voltmeter input).Measure several values of resistor (0, 50, 100..) first, and undo the voltage divider equation to solve for source resistance.Now you're ready. Insert FB, measure the voltage, and (based on the calibration above) calculate its impedance. You'll actually be measuring the magnitude, which is close enough. Most FBs will be somewhere between slightly inductive and resistive at this frequency, so it shouldn't be too far off.FBs are sold by their impedance at some frequency, most often 100MHz, so this is as good a method as any.I think you'll find the physically larger ones usually have more impedance, but it will also vary significantly with type, as there are three major classes of material used: LF, MF/wideband, and HF. If you sort them by both size and impedance, you should see a pattern like this, more or less.Such a setup will also work well for RF inductors in the range of L ~= (50 ohms) / (2*pi*(100MHz)) = 80nH, give or take a factor of 10 let's say. Or 10x higher inductances at 10x lower frequency, etc.Tim
Random values in MegOhmmeter - Page 1
Forum section: electronics / beginners

author: Jasonbit
author_rank: Regular Contributor
timestamp: January 30, 2019, 12:25:47 am
content: Hello,I am trying measuring the insulation resistance of this transformer trough this MegOhmmeter (https://uk.farnell.com/tenma/72-9400/tester-insulation-250v-500v-1kv/dp/2064096). But I receive the weird values. In this images you can see three diferrent value during resistance test. The values are always changing!Image 1:https://postimg.cc/Hjy1ZyzcImage 2:https://postimg.cc/4YwD7bfMImage 3:https://postimg.cc/kVpLwJtvWhat could be happening?I already checked with a multimeter and got the correct voltage values (250VDC, 500VDC and 1000VDC). And the test applied to a multimeter has a value of 9.9M OhmThanks

author: RoGeorge
author_rank: Super Contributor
timestamp: January 30, 2019, 12:34:44 am
content: Try measuring without the 2 spool of wires, using shorter leads (probes) instead.My best guess is those 2 spool of wires are nothing but huge coils, acting here as antennas, thus altering the measured value.

author: Andy Watson
author_rank: Super Contributor
timestamp: January 30, 2019, 12:51:14 am
content: Can you power the meter from a battery? If not, can you ground one of the power supply leads? I suspect that your power supply is coupling a large mains component into your meg-ohm meter - which is probably saturating the front-end of the meter. And as RoGeorge points out, this will not be helped by those long antennas.

author: graeme.c.payne
author_rank: Newbie
timestamp: January 30, 2019, 01:18:47 am
content: I agree with the above. As a general rule, the connection between the unit under test and the test/measurement equipment should always be as short as practical.Sent using Tapatalk

author: Jasonbit
author_rank: Regular Contributor
timestamp: January 30, 2019, 01:49:58 am
content: Thanks to your help.Yes, you are right. I did this test:image1:https://postimg.cc/7bs2xbTNimage2:https://postimg.cc/LnJZhRtFWhen I tested the transformed in the moment I press the button "Test" the value 685MOhms appear but disappear in the next second. Then it remains with the value1 MOhm. I repeat the process and I get another value.Thanks