hybridfree/eevblog-posts huggingface dataset:
How to wire front panel? - Page 1
Forum section: electronics / beginners

author: Noise0
author_rank: Contributor
timestamp: June 23, 2023, 06:03:39 pm
content: Hi, just an amateur here.When I build my electronic boards I find myself having to connect some front panel controls such as leds, potentiometers, switches, etc.Say that i have to connect a potentiometer on the front panel via 20cm wiring.I have to bring to it: Vcc, Gnd, and Vr.I wonder how to arrange these wires that go around the box in order to minimize picked up noise.Here a quick sketch to visualize my question.What is the best practice ? Lay them flat? Twisted? or shielded ?Thx

author: wizard69
author_rank: Super Contributor
timestamp: June 23, 2023, 08:48:16 pm
content: You are not going to like this but it depends.I'd commonly look for shielded twisted pairs or threes when running to an off board potentiometer. However I'm focused on industrial usage at work and we almost always have wire laying about. Often twisted pairs or tris are good enough.By the way don't use the shield as a ground conductor. You make an assumption that one end of a pot connection is at ground potential. It might be but that is not something you can count on with third party equipment. Beyond that shields are often bonded at entry to panel box or to the electronic hardware (drive), and keep separate from low level signals.
How to wire LiIon batteries to balance plug - Page 1
Forum section: electronics / beginners

author: isaacsong23
author_rank: Contributor
timestamp: May 10, 2017, 02:26:27 pm
content: Hello guys!!Does anyone have a schematic or link to show how to attach a balance plug to a homemade 4-cell battery?Thank you so much!Sent from my SM-G935F using Tapatalk

author: eKretz
author_rank: Frequent Contributor
timestamp: May 10, 2017, 02:29:34 pm
content: It depends on the plug/type. See here:http://www.tjinguytech.com/charging-how-tos/balance-connectorsFor JST connectors and regular (non-pouch) cells:Pin 1 on this balance connector would be the left side pin when looking at the side of the battery connector plug with the clip (or indexing pins) on the top and wires out the back.

author: isaacsong23
author_rank: Contributor
timestamp: May 10, 2017, 03:54:31 pm
content: Wow!!Thanks for the help!!:)morr clearer now hahaSent from my SM-G935F using Tapatalk
How to wire mains DPST switch lamp. - Page 1
Forum section: electronics / beginners

author: chibiace
author_rank: Regular Contributor
timestamp: June 20, 2013, 12:04:58 am
content: Hi i have a DPST switch with a built in lamp, which im going to put into my hakko fx888,the lamp is between switches like so-A1---/ ---A2-|(x)|-B1---/ ---B2-R9Yhttp://www.lightcountry.com/download/rocker/R9(R19).pdfthe original switch only has 2 prongs with phase from the power cable, and the other goes to the fuse board, the switch just breaks the phase inleti know i can wire the new one with A1 to A2 to make it work like the original, but how can i get the lamp to work when the switch is in one direction? do i have to break out neutral to B1?

author: David_AVD
author_rank: Super Contributor
timestamp: June 20, 2013, 12:16:15 am
content: A2 to incoming active, A1 to power transformer active, B1 to incoming/transformer neutral.The lamp is rated for mains voltage I assume?

author: chibiace
author_rank: Regular Contributor
timestamp: June 20, 2013, 12:19:14 am
content: yeah. thanks ill give it a go.

author: chibiace
author_rank: Regular Contributor
timestamp: June 20, 2013, 12:57:49 am
content: Heres a picture. Sits ok. Switch housing not the best
How to wire None - One - Both with Rotary Switch - Page 1
Forum section: electronics / beginners

author: hyperknot
author_rank: Contributor
timestamp: June 15, 2021, 08:02:14 am
content: Hi,I have a very simple problem. I'd like to make a light with 2 LED strips turn on with 0 - 50% - 100% power. I'd like to do this with a rotary switch.The 2 strips are independent from each other, but physically are in the same housing so when only one of them is on it looks like 50% power.I'm puzzled with the rotary switch though. Which type allows me to do this? The ones with the needed current rating on Digikey are the following for 3 positions:- DP3T- SP3T- DPDTI'm thinking I need a SP3T and solder 2 wires to one output for the 100% setting? Is this the right way to do it?

author: Renate
author_rank: Super Contributor
timestamp: June 15, 2021, 02:40:20 pm
content: There's two ways to do this, using a DP3T or a SP3T.The single pole way needs a diode and obviously only works for DC.

author: Terry Bites
author_rank: Super Contributor
timestamp: June 15, 2021, 04:45:59 pm
content: Here. Sorry about the wrong attachment.

author: hyperknot
author_rank: Contributor
timestamp: June 16, 2021, 12:34:18 pm
content: Thanks a lot, so DP3T is by far the simplest as I see.

author: Renate
author_rank: Super Contributor
timestamp: June 16, 2021, 12:50:54 pm
content: Well, you could also just keep the two strings together and wire them to a PWM dimmer.Twice the light is really only a bit brighter to our eyesYou'd probably want more like 1/4 bright, full bright.
How to wire one tactile dome button to act as switch in two separate devices? - Page 1
Forum section: electronics / beginners

author: alexg
author_rank: Regular Contributor
timestamp: January 27, 2018, 05:10:13 am
content: Hello, perhaps this is very very simple question to some but I can't figure out, can you help pls:I have on/off integrated circuit (LTC2955) that has a dome switch connected to it (circled on the illustration #1 below), pin PB on that chip is powered via chip's internal LDO via 900k pull up resistor, so the button obviously active low.I want to have same button to also send signal into Atmega328p chip's pin so I can monitor its state and intercept when it has been pressed. How should I wire that?

author: ataradov
author_rank: Super Contributor
timestamp: January 27, 2018, 05:36:24 am
content: Just take that PB pin and connect it to the input pin on the mega.

author: alexg
author_rank: Regular Contributor
timestamp: January 27, 2018, 05:44:20 am
content: Quote from: ataradov on January 27, 2018, 05:36:24 amThe voltage on PB pin is 4.3v (and according to datasheet can be anywhere from 3V to 5V) my atmega is powered is 3.3V , will that be a problem?

author: ataradov
author_rank: Super Contributor
timestamp: January 27, 2018, 07:19:58 am
content: Technically, yes. But depending on how critical the device is, you can probably get away with just a series current-limiting resistor. Or put a transistor for level conversion, if you have board space.

author: Brumby
author_rank: Unknown
timestamp: January 27, 2018, 07:27:52 am
content: Just run a diode from the Atmega pin to the PB pin.
How to wire up a composite camera? - Page 1
Forum section: electronics / beginners

author: XOIIO
author_rank: Super Contributor
timestamp: November 09, 2013, 05:09:16 pm
content: Hello everyone, I took apart one of those "spy car" things with a camera and grabbed the camera module out of it, it has ground, positive and a yellow lead which I can only think is the video signal. I don't know what voltage it runs at, I'll assume 5v, but I am wondering how to connect it to a TV to test it out. I'm guessing I need to make the connector with the yellow wire and ground but I don't know if the inside pole or the shield of the connector should be ground, perhaps someone has a wiring diagram?

author: garak
author_rank: Contributor
timestamp: November 09, 2013, 05:44:05 pm
content: 5V for the power isn't a bad assumption, but it's hard to be sure without knowing more about the specific camera. Basically what you want to do is this:Get a male Phono/RCA connectorConnect the "pin" of the connector to the yellow wireConnect the shield/ring of the connector to the black wire and to the ground of your power supplyConnect the red wire to the V+ of your power supply
How to wire up GSM Modem(DCE) With MAX485 - Page 1
Forum section: electronics / beginners

author: Sultanpepper123
author_rank: Regular Contributor
timestamp: February 18, 2020, 09:03:59 am
content: I am trying yo figure out how to directly connect a GSM modem (say SIM800) with a MAX485 . The purpose of this is to make an RS485 GSM Modem. I am struggling how to wire it up, do i wire the CTS of the DCE(Modem) to the RE/DE pin together ?
How to work with SPI on arduino and the STP16CP05 LED driver - Page 1
Forum section: electronics / beginners

author: Se3ker
author_rank: Newbie
timestamp: January 22, 2019, 09:25:36 pm
content: Hi,im trying to get thishttps://www.st.com/resource/en/datasheet/stp16cp05.pdfLED driver to work with Arduino.I've read about SPI but I don't understand it yet.I hooked up the LED driver to the Arduino Nano like this:1-GND -> GND24-VDD -> +5V2-SDI -> D11(MOSI)3-CLK -> D13(SCK)4-LE/DM1 -> D823-R-EXT -> 1K resistor -> GND22-SDO -> not connected21-OE/DM2 -> D10(PWM)I also put 16 LEDs anode to +5V and cathode to OUT0-OUT15Is this is the correct hookup?Can anyone please help me with Arduino code for blinking these LEDs?Thanks.
How to write a test bench that will fail if some outputs are not as expected ? - Page 1
Forum section: electronics / beginners

author: tigrou
author_rank: Regular Contributor
timestamp: January 02, 2020, 10:44:44 am
content: Hello,In verilog, it is possible to write test benches that set input ports to some values and print the output (to manually check modules are working correctly).Is it possible to explicitly specify in the test bench what values you expect as output, and the test to fail if those values are not met ?For example let's say I write a module that has A and B as inputs and C as output.I would like to check that C is same as what is defined in the table below.QuoteWhile searching info about GTKWave (and possible ways to do what I explain above) I have found thisscreenshotwhich show some values in red. Are those values because of test that does not meet some requirements ?

author: rstofer
author_rank: Super Contributor
timestamp: January 02, 2020, 03:53:46 pm
content: There are a couple of ways that I know about. No doubt there are others...if <some conditional test> thenwrite(<some message>);end if;ORassert <some conditional test> -- if the test is true, the following report and severity statements are not performedreport <some message> -- report the failureseverity failure; -- stop the test benchI suggest looking up the assert statement on the Internet, it's pretty handyThe signals are in red until they are defined. Early on, the value isn't known.

author: tigrou
author_rank: Regular Contributor
timestamp: January 02, 2020, 04:50:39 pm
content: Assert and other tests : thanks for info.Quote from: rstofer on January 02, 2020, 03:53:46 pmYes, in the example I provide, signals are not defined yet. That is why (AFAIK) there is a "xx..." label on data.I have foundsome examplesof red signals in GTKWave with some data defined (first page).I took a look atGTKWave manualfor more info (what red means) but could not find anything.

author: rstofer
author_rank: Super Contributor
timestamp: January 02, 2020, 04:58:31 pm
content: Look at i_wbs_cyc and note that it changes from red to green at the leading edge of the rst signal as do many other signals. Prior to reset, the values weren't defined and they're shown as both high and low in red. This is pretty common for simulators and it's also true for processes that use reset to initialize a signal.The xxxxxxxx is kind of redundant but is probably shown just to be pedantic. I don't understand the 00xxxxxx but apparently the high two bits are predefined.
How to "Zero" a scope's reading - Page 1
Forum section: electronics / beginners

author: ksat44
author_rank: Contributor
timestamp: August 07, 2022, 06:16:53 am
content: Hope this question isn't too basic, but I was wondering what setting is used to "zero" or rel out a reading you get on a scope. I'm picking up some low level noise prior to taking a measurement that I'd like the scope to ignore and just start at the 0V mark. I have a DC amp clamp, as well, which has no zeroing button on it that I was hoping I could do on the scope end of things in the same fashion, too.I see a feature called filtering which appears to do what I'm talking about, but I'm not quite sure that is the appropriate setting to use in my situation.Many thanks for any help...

author: tautech
author_rank: Super Contributor
timestamp: August 07, 2022, 11:24:02 am
content: ksat44I'd be very concerned if I owned a scope that wouldn't detect spurious signals when instead you need know how to manage them and understand what they might be so to know when to ignore them.The world is an electrically noisy place, much of it due to EMI/RFI from all manner of SMPS that surround us however some are much better than others.I had a customer that was adamant we had sold him a faulty scope as he had a 22KHz signal present in all scope measurements however having seen this before the hard part was convincing him otherwise however after check surrounding rooms and turning OFF all appliances and wallwarts the culprit was found in a power socket behind a curtain in the same room as the scope !With a scope, the probe if used incorrectly is a mighty fine antenna but one can take advantage of this fact using it like a near field probe which can prove very useful on occasions where it can be used to sense ignition pulses from small petrol motors as an aid to tuning.Anyways back to your noise, are you using a DSO ?Screenshots please showing noise frequency and the active channel input menu.

author: wn1fju
author_rank: Frequent Contributor
timestamp: August 07, 2022, 11:32:56 am
content: Yes, your question seems a bit ambiguous. If it is the case that you have a signal with a DC offset, so that the baseline of the scope isn't at zero, you could always set the scope for AC coupling - this will eliminate the offset. If it is simply noise that sits around zero, then indeed reducing the scope's bandwidth (the filter setting) will reduce the noise somewhat.But as tautech says, you want a scope to see the actual truth - you wouldn't want one that doesn't.

author: Andreas
author_rank: Super Contributor
timestamp: August 07, 2022, 06:10:11 pm
content: Hello,on my scope there are several options to remove the DC-Offset of a DC current clampwhich are created by the current clamp offset of the operational amplifier or partly also the earth magnet field.the easiest way is to use the "offset" function with "auto-zero" in the channel menue.(of course you can also enter a manual offset value).Other options are use "zero all ranges" in the channel menu or use a math function in the math menue.with best regardsAndreas
How toroid transformer dissipates the heat generated by inner windings ? - Page 1
Forum section: electronics / beginners

author: BravoV
author_rank: Super Contributor
timestamp: May 22, 2018, 08:54:59 am
content: As its buried and encapsulated deep in the middle, and also sometimes with another layer/s of inter winding isolation added ?When it comes to heat dissipation, does the common EI core has more advantage ? As it has much more openings and exposed slits.Scope of discussion is mains transformer, say common step down.

author: Zero999
author_rank: Super Contributor
timestamp: May 22, 2018, 10:27:43 am
content: Toroidal transformers tend to be more efficient than EI core transformers, so there's less heat to deal with.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 22, 2018, 10:53:04 am
content: Yes, the core and inner windings have to conduct their heat through the outer layers.A good reason for transformers to be impregnated with varnish, to reduce thermal resistance.Toroids also have more surface area than shell type transformers.Tim
How use salvaged transformer to make a variable dual bench power supply????  - Page 1
Forum section: electronics / beginners

author: Dhanushka
author_rank: Regular Contributor
timestamp: October 01, 2019, 07:20:57 am
content: Dear all,I salvaged a transformer from an old Sony stereo audio system. It has 2 x 12 V/2 A (center tapped) and 2 x 20 V/3 A (center tapped) outputs. These wingdings are isolated for the continuity testing. But when I measure the voltage they had relative measurements. However, I use two lines of 12 V as an 24 V input to a variable lab power supply module. (https://www.aliexpress.com/i/32769033201.html) Also, one 20 V output as a input to another power supply module to make dual output power supply. But when I made this I could not make dual power input to a circuit combining the as two separate power supplies. (positive of one is connected to negative of another) When I connect these two, current limiting indicator glows. The negative lines has a voltage drop of about 4 V. Please tell me how use this multi output transformer to make a dual variable output power supply?

author: xavier60
author_rank: Super Contributor
timestamp: October 01, 2019, 07:35:36 am
content: That should work. With the power off, do you find any continuity between the output terminals of one module to the other?Also check between the windings again. Maybe there is something on that transformer connection PCB.

author: tautech
author_rank: Super Contributor
timestamp: October 01, 2019, 10:01:15 pm
content: Transformer winding phasing is most likely wrong.Disconnect prior to the rectifiers and experiment with secondary connections using a bulb that will indicate glow when phasing is wrong.

author: tunk
author_rank: Super Contributor
timestamp: October 01, 2019, 10:11:37 pm
content: The heatsink in the front of the photo looks a bit small - what's the max current will you draw from that one?You may also want to add a fan at the back, and ventilation holes at the sides.
How using  Gotek SRF1M44_DU26 - Page 1
Forum section: electronics / beginners

author: madao
author_rank: Frequent Contributor
timestamp: November 23, 2019, 08:56:25 pm
content: HelloI have here a Gotek SRF1M44-DU26, a Floppy emulator, slimline-variants.I owned 2 Gotek SRF1M44-U100 (Standard), it works fine. Selfformat-function runs fine (2 button pressing and switched unit on, it make 1000 drive into one USB Stick )DU26-Variant is much other, has not self-format-function, but read 1Gb (FAT32 formatted) Stick without problem.But this shitty piece crap is too stupid to writing file into USB Stick. IT write and file is preset. But if i plug USB stick out, this file is away. pressing of button doesn't save file to stick. Only one success by over 30 fail. (Stick from U100-devices is also used)How wrong do i with him ? Or it is just a money-waste ?It is for Tek TDS754C (in future TDS754D )regardsmatt

author: madao
author_rank: Frequent Contributor
timestamp: December 05, 2019, 07:19:23 pm
content: Solved
How will my circuit behave in certain situation?  - Page 1
Forum section: electronics / beginners

author: cichy45
author_rank: Contributor
timestamp: June 19, 2022, 06:04:13 pm
content: Hi All!I want to have simple board to remote control charging for my escooter. I want to have it between charger and battery, so I can power it from charger but disconnect battery from charger if necessary.However, I am not sure what will happen if I left charger plug disconnected and connect battery plug first. In this scenario I would like to have the board not powered (ie, not have the ESP WEMOS D1 MINI powered from battery). Will this circuit in this scenario keep the P-Mosfet open as the gate and drain are shorted by resistor?Side note: pmosfet has internal zener diode esd gate protection, nmos does not so I added one.
how work this? - Page 1
Forum section: electronics / beginners

author: Daxxin
author_rank: Regular Contributor
timestamp: December 31, 2016, 06:23:05 pm
content: HPWRUP while switching on we have a short pulse , then LRST and LHLT is inverted to HPWRUP right?LRST and LHLT is connected to motorola reset and halt pin which one is normal? LRST remain high or LRST remain low?because LHT remain 5V and LRST goes 0V

author: Benta
author_rank: Super Contributor
timestamp: December 31, 2016, 06:54:02 pm
content: No inversion.If HPWRUP is low, LRST and LHLT are pulled low as well. M68K design?Benta.
How would I test these with a meter to see if good? - Page 1
Forum section: electronics / beginners

author: user1868
author_rank: Newbie
timestamp: September 29, 2020, 02:41:17 am
content: Theres a bunch of these but I dont have schematics for the board.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: September 29, 2020, 02:48:08 am
content: There are websites for matching SMT codes to part numbers.Without knowing what it is (BJT, FET, (TVS) diodes, etc) the simplest is to poke around in diode mode to find PN junctions. Same parts should have PN junctions over the same pins. but when testing in circuit you add extra uncertainty because of surrounding circuitry.Another way is power the circuit up and look with a scope at signals passing these components. Do they make sense?

author: bob91343
author_rank: Super Contributor
timestamp: September 29, 2020, 05:40:01 am
content: https://datasheet.octopart.com/BAW567-Diodes-Inc.-datasheet-115921.pdf

author: Doctorandus_P
author_rank: Super Contributor
timestamp: September 29, 2020, 12:01:23 pm
content: Give a man a fish and he can eat for a day...
How would I wire this? - Page 1
Forum section: electronics / beginners

author: 6010fd12
author_rank: Newbie
timestamp: June 01, 2021, 01:24:34 am
content: So I'm looking to have a similar setup as the person in thisvideowhere I have a laptop power supply powering LED's and a rumble motor through some switches. I only have some basic knowledge on electronics but I do know that the power supply's voltage has to match the specifications of both the LED's and the motor, however the amp rating needs to be at or above the needed amount for the devices (correct me if I'm wrong).I'm looking to purchase thesesmotorsor possible a single unit instead of two since it seems kind of overkill. What type of LED strips do I need to purchase that I could also add into this circuit that would work with the same power supply. I was thinking of purchasing thispower supply. The only confusing part for me is that after watching a bunch of arduino videos people usually put resistors in the same circuit as the led but in the video I linked above it does not look like the person had resistors in his circuit.

author: bob91343
author_rank: Super Contributor
timestamp: June 01, 2021, 03:32:58 am
content: The resistors limit the current. Without them, the LEDs would overheat and die.

author: james_s
author_rank: Super Contributor
timestamp: June 01, 2021, 05:53:56 am
content: There exist LEDs with built in resistors but they are rare. It's trivial to calculate current limiting resistors for LEDs, you have to know the power supply voltage, the forward drop of the LED(s) in question, the current you want to drive them with (10mA is probably reasonable) and Ohms law.

author: rdl
author_rank: Super Contributor
timestamp: June 01, 2021, 06:25:59 am
content: You would need the current limiting resistors if you decide to use individual LEDs. However, you can get those pre-made LED strings/strips with built in current limiting. They just need a power supply with the correct voltage and sufficient current rating. You might also go to your local big box home improvement store and check out the shop lights and under cabinet lighting.
How would you add pi filters to a bipolar power supply? A or B? Picture attached - Page 1
Forum section: electronics / beginners

author: Metatronic_Mods
author_rank: Contributor
timestamp: July 19, 2017, 11:28:07 pm
content: I think my confusion here stems from the fact that I still have a hard time visualizing current flow in bipolar powered circuits. But, which would be the proper layout, or is it something else? Picture attached.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: July 20, 2017, 12:21:14 am
content: My vote goes to A.The reason: you want to keep the ground continuous.If you use 'B' and the source and device have a ground connection, the inductor in the ground lead gets shorted.Jay_Diddy_B

author: timb
author_rank: Super Contributor
timestamp: July 20, 2017, 12:21:43 am
content: Think about it like this: If you were to use that -12V rail as GND at your device, then what you have labeled as GND would be +12V and what you have labeled as +12V would actually be +24V.Essentially, voltage is the potential difference between two points. So, the difference between -12 and +12 is 24, right? Make sense?

author: timb
author_rank: Super Contributor
timestamp: July 20, 2017, 12:35:19 am
content: Quote from: Jay_Diddy_B on July 20, 2017, 12:21:14 amNo, they're polarized caps. If you use A, the caps on the -12V rail would be backwards and eventually break.Remember, 0V is more positive than -12V. You want the + end of the polarized cap towards the more positive end.Edit: Actually, looking at his schematic again, neither A or B is correct. It should be A with the -12V caps flipped.This would actually be correct:

author: Metatronic_Mods
author_rank: Contributor
timestamp: July 20, 2017, 12:56:13 am
content: Quote from: timb on July 20, 2017, 12:35:19 amI didn't mean to imply polarized caps, that's just the default symbol I use. Polarized are indicated with a +

author: Metatronic_Mods
author_rank: Contributor
timestamp: July 20, 2017, 12:59:12 am
content: Quote from: blueskull on July 20, 2017, 12:38:04 amYou say don't break GND, but B has GND broken by one of the inductors. I'm confused.

author: Metatronic_Mods
author_rank: Contributor
timestamp: July 20, 2017, 01:04:48 am
content: Quote from: timb on July 20, 2017, 12:21:43 amYeah, that's how I tend to think about it. I think the reason I get confused is that the systems I work on are never balanced well (more current in the + rail than in the - rail), so there's always a return current in the GND (or what you might label +12V) going back to the power supply.

author: timb
author_rank: Super Contributor
timestamp: July 20, 2017, 10:50:49 pm
content: Quote from: Metatronic_Mods on July 20, 2017, 12:56:13 amOkay, then A would be correct. As for your symbols, the use of a straight line over a curved line to represent a non-polar cap isn't really common anymore (I've only ever seen it in old American schematics). You might want to switch to using two straight lines, which is the current international standard, so your intent is communicated clearly. After all, that's a big part of engineering.
How would you characterize this 2nd Gen Current Conveyor? - Page 1
Forum section: electronics / beginners

author: Mattjd
author_rank: Regular Contributor
timestamp: July 30, 2017, 06:45:05 pm
content: Hi, doing research on memristor emulators. The proposed circuit of the paper I am currently reading isNow the current conveyor on the right I recognize as a voltage to current converter aka a VCCS. The one of the left I am unsure. I am just learning of current conveyors today andhttp://cas.ee.ic.ac.uk/people/dario/files/E416/cc_handout07.pdfhas no example of that topology.The paper is question adds no specific details either.What I do know about current conveyors though is that the voltage of X is equal to that of Y. So the feedback from the voltage multiplier is being used to influence the voltage of X. Why this is important I am unsure.
How would you solder the MCU & CPLD? - Page 1
Forum section: electronics / beginners

author: rthorntn
author_rank: Frequent Contributor
timestamp: May 30, 2018, 07:44:28 am
content: Hi,I'm really asking about soldering just the MCU & DPLD for just now.So I got some boards from pcbway, mainly to practice soldering although it would be cool if I could get them working.I got this for $1 each:https://www.pcbway.com/project/shareproject/CPLD_Fun_Board__Arduino_STM32F103_and_Altera_MAX_II_CPLD.htmlAnd I have both a uyue 946C hot plate and an atten 852d hot air wand.I have paste, I have a metal stencil for STM32F103C8T6 (48LQFP) and EPM240T100C5 (100TQFP).The issue I see is the CPLD is on the front and the MCU on the back. I don't see how I can just use the hot plate. I think I will have to maybe hot plate the CPLD and hot air the MCU?Thanks for looking.CheersRichard

author: rstofer
author_rank: Super Contributor
timestamp: May 30, 2018, 01:42:42 pm
content: Those should be fairly easy to solder by hand. Google for 'drag soldering' and watch a couple of videos.It is inevitable, and totally expected, that you will bridge a couple of pins. Just make sure you have some very fine Solder Wick and plenty of flux.Flux is the key to the process. Run a ribbon of flux around the pads, place the device, tack 2 opposing corners and drag solder the rest.It's really easy... I don't have one of the club foot soldering tips, I just use my 1/8" chisel tip and it works well. It doesn't hold as much solder so I can't always get all the pins down one side but it all works out.If you want, you can use the hot plate method for one chip and just drag solder the other. Drag solder the one with the widest pin spacing if they are different.ETA:Did I mention lots of flux? Lots of flux!https://www.amazon.com/MG-Chemicals-8341-10ML-Clean-Syringe/dp/B00425FUW2

author: agehall
author_rank: Frequent Contributor
timestamp: May 30, 2018, 01:44:22 pm
content: I concur with rstofer. Dragsolder is the easiest way to go. If you need to you can also do a quick reflow to clean things up a bit afterwards.
how? - Page 1
Forum section: electronics / beginners

author: wiiw
author_rank: Newbie
timestamp: November 22, 2013, 08:37:04 am
content: how can i control the speed of the 3 phase squirrel cage induction motor.

author: Simon
author_rank: Unknown
timestamp: November 22, 2013, 08:38:47 am
content: sounds like you may need to switch each phase with a triac, not sure how you set each triac gate voltage though.

author: strangelovemd12
author_rank: Regular Contributor
timestamp: November 22, 2013, 08:44:33 am
content: http://youtu.be/E3BS8CO9APAAlso, you'll generally get better, quicker responses with a more informative post title.

author: Simon
author_rank: Unknown
timestamp: November 22, 2013, 10:32:15 am
content: That is true, which is why I was not overly enthusiastic in my reply

author: miceuz
author_rank: Frequent Contributor
timestamp: November 23, 2013, 01:07:56 am
content: It's called VFD - variable frequency drive.In essence three PWM waveforms are dumped into three phases of the motor to emulate current running thru windings of the motor. The motor construction is such that it will make a certain amount of RPM at 50Hz, you emulate less than 50Hz to get slower speed or (a bit) over 50Hz to get faster.I've made a VFD out of slap together modules, it's nice as an excercise, but to get efficiency and power you better buy one. Yes, vfds are quite expensive.

author: Stonent
author_rank: Super Contributor
timestamp: November 23, 2013, 04:03:23 am
content: Quote from: wiiw on November 22, 2013, 08:37:04 amhttp://www.electrical4u.com/speed-control-of-three-phase-induction-motor/

author: moepower
author_rank: Contributor
timestamp: November 23, 2013, 04:14:08 am
content: There are a few ways:* Changing the rotor resistance (if it is a wound rotor induction motor). Typically used to start large inertia mechanical loads (e.g., mills) and offers limited speed control. Not very efficient since you're wasting energy through the resistor.* Pole changing - the number of poles in the stator windings could be changed if the electrical wiring is accessible through a controller or multiple stator windings exist. Only gives specific speed changes and not very practical.* You can change windings between Star and Delta connection for 2 more speed settings.* Varying the line voltage magnitude - Works for a limited range of speeds, sometimes used on small motors driving fans.* Changing the line frequency.The most common method is a combination of the last two: changing line frequency and voltage magnitude. This is achieved through a Variable Speed Drive via Pulse Width Modulation (PWM) as previously mentioned by another user. PWM allows you to synthesize a voltage waveform with different line frequencies and voltage magnitudes that are supplied to the motor terminals. An induction motor rotor "chases" the rotating magnetic field generated by the sequentially displaced three-phase currents in the stator windings. The rate at which the magnetic field rotates is proportional to the electrical frequency generated by the VFD.
Howdo these car battery testers work? - Page 1
Forum section: electronics / beginners

author: dog80
author_rank: Regular Contributor
timestamp: May 28, 2013, 05:29:48 pm
content: Tester here:http://www.cadex.com/products/spectro-ca-12-gaI have a cheap knockoff I bought from dealextreme.com and have tested various batteries and seems to come pretty close to the actual CCA value.How does it work?

author: grumpydoc
author_rank: Super Contributor
timestamp: May 28, 2013, 06:45:44 pm
content: Wild guess:1) Measure battery voltage - gives state of charge2) Apply know load of at least a few A for a couple of seconds - measure drop and from that the ESR of the battery3) See how long the voltage takes to recover to that measured in 1 - will give some idea of the state of the plates.I assume CCA is not far from the short circuit current which you will know if you know the ESRBut, as I said, wild guess.

author: Paul Price
author_rank: Super Contributor
timestamp: May 28, 2013, 10:46:11 pm
content: Nah, not the way mine's work.Mine reads capacity, CCA, and state-of-charge of a starter battery in a 15-seconds test using electrochemical impedance spectroscopy (EIS) and genetic algorithms(GA). Capacity is the leading health indicator of a battery, and my capacity estimation is possible by expanding on battery-meter telepathy and adding an esoteric algorithm that completes an otherwise lengthy test of 40 million computer instruction cycles in 15 seconds. My device should not to be mistaken with impedance testing that reads internal battery resistance only. Batteries have improved and resistance-related failures are isolated. My circuit uses a genetic matrix that outsmarts most starter batteries trying to hide their potency, yet operation has been verified by psychics and so gives a pass/fail on capacity.

author: Unknown
author_rank: Unknown
timestamp: May 28, 2013, 11:28:07 pm
content: I just built a BS detector, and I applied it to that last post, and, well, you've fried it. I hope you're happy.

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: May 28, 2013, 11:40:44 pm
content: It's also a quote from the aforementioned link.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: May 29, 2013, 02:34:49 am
content: That's the funniest thing I've heard in a while.

author: ConKbot
author_rank: Super Contributor
timestamp: May 29, 2013, 04:39:23 am
content: I'm sure Cadex is blowing smoke out their ass and they dont know much about batteries

author: grumpydoc
author_rank: Super Contributor
timestamp: May 29, 2013, 10:37:24 am
content: QuoteLOL
Howland Current Source Circuit - Page 1
Forum section: electronics / beginners

author: wanxing
author_rank: Newbie
timestamp: November 06, 2018, 02:22:01 pm
content: Hi, I am trying to design a precision current source circuit of 1A for my project. I found the Howland Current Source circuit when doing some researches, but I am not understand about the working principle or operation of it. Can anyone explain it ? The circuit I found is shown in attachment. Thanks in advance.

author: t1d
author_rank: Super Contributor
timestamp: November 06, 2018, 03:52:15 pm
content: Well, your question will require a lot of information that is already out there. So, I suggest you do some study and come back, if you have specific questions about certain operations. I often post broad questions, because I do not know where to begin, nor what terms to search. Here is what I think will help you...1) This is a rather typical constant current source circuit.2) The heart of the circuit is the operational amplifier.3) The op amp is fitted with a feedback loop circuit4) The feedback circuit gives the op amp the "information" needed to adjust the current, to keep it at a consistent level.I suggest that you look on YouTube, for these tutorials1) Op Amp operations.2) Feedback loop circuit operations - both current and voltage.3) Precision current source circuit.You probably won't have to spend more than 15 minutes, per subject.There are special all-in-one ICs, just for this purpose. Check into those, at your favorite supplier. I like Mouser.com.Do well and we look forward to your future questions.

author: Zero999
author_rank: Super Contributor
timestamp: November 06, 2018, 04:47:17 pm
content: The key to understanding it, as with any op-amp circuit, is that the op-amp adjusts its output to make both of its input voltages equal. Here are some links which describe the Howland current pump circuit in more detail. The last one is to a simulator, which can be useful when studying any circuit.http://www.ti.com/lit/an/snoa474a/snoa474a.pdfhttps://www.edn.com/design/analog/4430167/Op-Amp-Current-Sources--The-Howland-Current-Pumphttp://www.falstad.com/circuit/e-howland.html

author: Smokey
author_rank: Super Contributor
timestamp: March 22, 2025, 09:57:42 pm
content: I know.. old post.. but..Code:https://www.youtube.com/watch?v=i3464q6PqrECode:https://www.youtube.com/watch?v=rdQXkOD1wIU

author: RoGeorge
author_rank: Super Contributor
timestamp: March 23, 2025, 05:04:11 pm
content: The Howland pump is great as a voltage to current converter, but I wouldn't use it as aprecisioncurrent source, because in practice the Howland pump is very, very, very sensitive to resistors matching.

author: Zero999
author_rank: Super Contributor
timestamp: March 23, 2025, 05:39:22 pm
content: Use an instrumentation amplifier IC and resistor matching isn't an issue.Howland intrumentation amp.asc
howland integrator - Page 1
Forum section: electronics / beginners

author: ArjunSukumar
author_rank: Contributor
timestamp: October 10, 2015, 05:58:11 am
content: Hi guys,I want to generate a sawtooth waveform using an Howland integrator or de boo integrator. I don't know how to proceed with the design. Suggest me any video lectures links or text books which describes the working and design stepsThanks in advance

author: LvW
author_rank: Frequent Contributor
timestamp: October 10, 2015, 03:50:19 pm
content: Quote from: ArjunSukumar on October 10, 2015, 05:58:11 amOK - here is the desription of a DEBOO integrator (based on a Negative Impedance Converter - NIC):* Take a simple RC first order passive lowpass; time constantT=RC.* Connect the pos. input node of a non-inverting opamp stage (gainG=1+RN/RL) to this RC lowpass.* Place another resistor RP between opamp output and pos. input node.* MakeRP*RL/RN=R* Result: The negative input resistance of the NIC (at the pos. input)Rin=-RP*RL/RNcompensates the damping properties of R.* Integrating function:H(s)=G/sT* Attention: When this integrator is used as a stand-alone unit (and not within a stabilizing negative overall loop), the ratio RL/RN must be selected slightly larger than R/RP to ensure a stable DC operating point.
Howto find own threads in this forum? - Page 1
Forum section: electronics / beginners

author: eneuro
author_rank: Super Contributor
timestamp: June 14, 2014, 08:56:16 pm
content: Hello,Too muchtoday and I have no idea how to find threads on this forum I've send post or created new own topic?I see only:QuoteTrying to search for my own posts using "*" by I get this message:Quote

author: mariush
author_rank: Super Contributor
timestamp: June 14, 2014, 09:05:50 pm
content: Click on Profile.Move mouse over Profile Info , move mouse over "Show posts..." but don't click. A menu should show up and you can select there Show topics.ps. You can then bookmark the URL .. select the url with your mouse, drag it on your toolbar or press Ctrl+B (in most browsers).

author: Greorge
author_rank: Regular Contributor
timestamp: June 15, 2014, 06:14:25 am
content: Glad to see this solution, as I had difficult time to find answers to my posts too.

author: eneuro
author_rank: Super Contributor
timestamp: June 15, 2014, 10:52:57 am
content: Quote from: mariush on June 14, 2014, 09:05:50 pmTricky, tricky, while when moving aboveProfileit shows only a few other options and you have to click to see another ones
howto test a BA 718  - Page 1
Forum section: electronics / beginners

author: ME
author_rank: Frequent Contributor
timestamp: October 07, 2025, 01:03:36 pm
content: Can anyone tell me how to test a BA718 dual opamp , the datasheet give no test circuits ,I am in need of a way to do a go/nogo test ,is it possible?, is there a circuit to do this?, Thanks.

author: jwet
author_rank: Frequent Contributor
timestamp: October 08, 2025, 03:22:43 am
content: Its a pretty generic dual op-amp. A simple test would be to see if it will operate as a follower. Provide power (3-18v), connect - input to output, provide a small DC voltage between .2v and Vcc-2v and see if it acts like a follower. Perhaps load the output with a 470 ohms or so. You can also see if it draws current like the data sheet graphs- approx 1.5 mA. It is basically a second source of a an LM4558, an old jelly bean. An LM 358 would likely work in the same spot.Good Luck.
Howto Use 120VAC rated Neon Indicator on 240VAC Circuit - Page 1
Forum section: electronics / beginners

author: edtyler
author_rank: Contributor
timestamp: November 08, 2022, 03:50:40 am
content: HI,I need to replace a defective 240VAC Neon indicator on a power supply.There is no 120VAC anywhere in the device, as it is powered from the 2 non-grounded conductors in a typical US residence. There is a ground, but it should never be used to carry current.I have a supply of 120VAC rated Neon indicators that I'd like to use. These, presumably, have a series resistor to limit current once the lamp strikes.It seems there may be two choices: 1) add an additional series resistor, but I'm not quite sure how to calculate the value of this resistor. Perhaps the value would be (Desired voltage - rated voltage)/existing current when lit at 120V?or 2) Hook up two of the 120V indicators in series. This may suffer from the problem that once the first bulb strikes, then the current limit resistors added together might prevent the second bulb from striking.. Also I have never seen this done - 2 neon bulbs in series..I'm looking for ideas on which approach would be more reliable/practical. No, I don't want to buy a 240V rated neon indicator. Although I do have a supply of the 120V Neon indicators, I don;t really want to destroy too many of them doing testing.Thanks in advance for any suggestions.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 08, 2022, 04:21:12 am
content: Try 100k, should be right in the ballpark when combined with the 33k or so already inside the indicator.

author: bdunham7
author_rank: Super Contributor
timestamp: November 08, 2022, 05:34:31 am
content: https://www.intl-lighttech.com/instrumentation-sensor-light-sources/neon-lamps
HP 16500 Logic Analyzer "doesn't like" clock signal (thinks it's always high) - Page 1
Forum section: electronics / beginners

author: Phaseseeker
author_rank: Regular Contributor
timestamp: October 02, 2022, 04:20:31 pm
content: Pretty much as the title states; HP16500 + 16510 State/Timing card, in state mode. The analyzer complained about the clock being slow or missing, so I connected it to one of the input channels (same pod) and it sees it as always high. I checked with a scope and the clock is there, there's a bit of ringing but it might be caused by the way I was probing it, either way the device that uses that clock runs without issues.The clock signal in question is a 4MHz clock being generated from an ATTiny85 with TMR0 in CTC mode (internal oscillator set at 16MHz and divided by the timer to 4MHz); I did this because I didn't have an oscillator module of the right frequency and the device under test doesn't have the ability to output a clock when run from its internal oscillator.

author: jmelson
author_rank: Super Contributor
timestamp: October 02, 2022, 05:07:17 pm
content: I use Tek analyzers. But, can it view the clock channel as an ordinary data channel in timing mode? That would allow the analyzer to self-clock. Then, you could tell if the clock channel was bad, or not connected. Does this analyzer have variable logic levels? Check what logic voltages it is set for.Jon

author: Phaseseeker
author_rank: Regular Contributor
timestamp: October 03, 2022, 10:20:37 am
content: I did some more testing, turns out the problem was in what HP calls "tip isolation network", basically a small RC circuit which is put in series with each channel to terminate the cable. I made my own PCBs with said RC networks and turns out I managed to swap two of the resistors on some of the lines. Obviously the last place I checked, since I had already used the PCBs without issues (on systems with slower clocks)...Thanks anyway
hp-1707b- - Page 1
Forum section: electronics / beginners

author: guitarmike000
author_rank: Newbie
timestamp: April 15, 2016, 01:55:26 am
content: hello newby here but with a whole room full of electronic equiptment been collecting for past 3 years. so i will be asking alot of questions for a long time to come. my issue at present is a purchase of hp-1707b of the flea,and found the 110 plugin hanging out the back i would appreciate help with color code matchup with numbers on circuit board. thanks mike.

author: tggzzz
author_rank: Super Contributor
timestamp: April 15, 2016, 09:01:56 am
content: The first thing to do is find the service manual. There may be free ones available, if nothttp://artekmanuals.com/manuals/hp-manuals/are cheap and acceptable quality.

author: danadak
author_rank: Super Contributor
timestamp: April 15, 2016, 11:32:17 am
content: Free manuals -http://bama.edebris.com/manuals/www.agilent.comhttps://www.raymond.cc/blog/site-with-free-service-manuals-and-datasheets/http://www.sphere.bc.ca/test/manuals.html#catalogRegards, Dana.

author: guitarmike000
author_rank: Newbie
timestamp: April 15, 2016, 09:33:58 pm
content: thanks, already have all 219 pages of hp manuel am cross eyed from searching it to no avail. was kinda wishing someone would take 5 minutes to open theirs up. maybe asking too much. but thanks for helping mike

author: tautech
author_rank: Super Contributor
timestamp: April 15, 2016, 09:43:24 pm
content: Quote from: guitarmike000 on April 15, 2016, 01:55:26 amPhoto of your problem might help.How many wires?Colors?

author: tautech
author_rank: Super Contributor
timestamp: April 16, 2016, 07:48:58 am
content: The OP sent me this PM:1 2 3 15 7 8---9 jumped across top layout.middle 10below 10 is 124 5 6 10 13 12---13 is jumped. no 1---4 jumped gry. no 2 blk/red no 3 blk/yel no 15 blk/grn no5 and 6 solid blk. circuit board info 5080-6875 c-11-39-32336. am trying to fiqure out how to send pics i took to email. first time ever. as soon as i can ill send them. then this will make sense. 3 wires were not connected.i put them on 15,5,6. thanks mikeIt would appear the voltage selector has been disconnected from the transformer taps and he's struggling to make sense of it.Can anybody take a pic of theirs and post it?

author: guitarmike000
author_rank: Newbie
timestamp: April 16, 2016, 11:42:15 pm
content: help please

author: guitarmike000
author_rank: Newbie
timestamp: April 18, 2016, 11:39:54 pm
content: well good news, just picked up another hp 1707b, so problem solved. thanks for all the insight. thanks mike