hybridfree/eevblog-posts huggingface dataset:
using a fluke 83 - Page 1
Forum section: electronics / beginners

author: m3vuv
author_rank: Super Contributor
timestamp: November 16, 2021, 12:00:40 am
content: Hi all,i need to take some measurements on a cct that calls for a voltmeter with at least 10mohms per volt,can i use a fluke 83v for this,if not an avometer 8mk2,tia.

author: bdunham7
author_rank: Super Contributor
timestamp: November 16, 2021, 12:17:48 am
content: Quote from: m3vuv on November 16, 2021, 12:00:40 amThat sounds like an ammeter to me!I don't kvetch over minor typos or deliberately misconstrue every small imprecision of grammar or terminology, but I really can't understand any of what you are saying here.The Fluke 83 should have an input impedance of about (but not precisely) 107ohms, or 10 Megohms, or 10M for short. So ohms-per-volt depends on range.

author: Benta
author_rank: Super Contributor
timestamp: November 16, 2021, 12:34:38 am
content: Quote from: bdunham7 on November 16, 2021, 12:17:48 amNope, that was in the good old days with AVO-meters. Modern DMMs have the same input resistance regardless of range. Here, as you say, 10 Mohms.

author: m3vuv
author_rank: Super Contributor
timestamp: November 16, 2021, 01:10:36 am
content: should of said megga ohms,its to take readings on a bradley ct417c that i am trying to repair,its from 1965,in the service manual it calls for a valve voltmeter of at least 10 megga ohms per volt,so as not to load it i pressume.?

author: bdunham7
author_rank: Super Contributor
timestamp: November 16, 2021, 01:11:33 am
content: Quote from: Benta on November 16, 2021, 12:34:38 amTrue, the ohms part doesn't change. But as the voltage range changes, so does the expression ohms/volt. Although you typically wouldn't use that expression to describe a modern DMM, the 1000V range is actually 10,000 ohms per volt, and so on. So when you compare an old analog meter to a modern DMM in an application where this might matter, you have to consider the issue.

author: bdunham7
author_rank: Super Contributor
timestamp: November 16, 2021, 01:15:11 am
content: Quote from: m3vuv on November 16, 2021, 01:10:36 amBetter check those specs, that doesn't sound right at all, especially the Avometer you mentioned. A VTVM might be something like 11 Megohms, but not ohms per volt.
Using a Function Generator and Power Supply - Page 1
Forum section: electronics / beginners

author: eev_carl
author_rank: Regular Contributor
timestamp: February 13, 2018, 01:16:46 pm
content: Hi,I built the attached circuit and was using a Rigol DP832 for VCC and a Rigol DG 1022 for VB. The 1022 was set to a DC waveform. On the breadboard, the ground of the power supply was connected to the ground of the function generator (same rail). I figured that the floating ground of the power supply would "lock into" the ground -- probably mains ground -- of the function generator.I noticed that the current was jumping around a lot when I was measured IE with a multimeter. I replaced the 1022 VB with a port on the DP832 that has a common ground and the current stablized.Is there a way to use the function generator in a similar way (the dial on the 1022 is more convenient)?Thanks,Carl

author: danadak
author_rank: Super Contributor
timestamp: February 14, 2018, 12:21:15 pm
content: What waveform were you driving into the base, frequency, amplitude, offset ?Regards, Dana.
Using a Homekit relay in Australia - Page 1
Forum section: electronics / beginners

author: rzyebay
author_rank: Newbie
timestamp: September 11, 2023, 11:03:48 am
content: I have conducted a search in forums using relevant keywords but did not find information addressing my question. I apologize if a similar inquiry has been made previously.I am currently establishing a smart home system. In Australia, most of the gang switches compatible with Homekit either instable or come with a significantly high price tag. As an alternative, I am considering the use of a remote control relay to achieve similar functionality. The relay I have in mind has the capability to convert a conventional gang switch into a smart switch by integrating it into the circuit.I understand that using SAA unapproved gang switches is illegal in Australia, but I am uncertain about the legality of installing such a relay. I plan to have a qualified electrician handle the installation, but my electrician are unsure whether installing this relay is permissible or not.Are there any regulations or guidelines that either prohibit or permit the installation of such relays in Australia?

author: SmallCog
author_rank: Frequent Contributor
timestamp: September 11, 2023, 11:26:38 am
content: I’m not an electrician however if I was looking to get advice on a situation like this I’d speak to a sparky that does industrial work.Relays (or contractors) switching loads, including via plug/socket is common in industrial automation.Be aware of your VA rating with relays, they might be rated to handle 240v and rated to handle 10A yet have a significantly lower VA.A smart home is just a fancy variety of SCADA

author: rzyebay
author_rank: Newbie
timestamp: September 11, 2023, 12:59:00 pm
content: Thank you for your advice. Sparky do sell similar product like CLIPSAL ICONIC WISER CLP5011WSZ | WISER MICRO MODULE SWITCH. I've checked the page and didn't see any SAA approved or similar term of this product. I will try ask them if they come with any certificate that allow me to integrate it into circuit.

author: Marco
author_rank: Super Contributor
timestamp: September 11, 2023, 01:47:38 pm
content: Google tells me that only the articles in AS/NZS 4417.2 need certification, the rest just needs to meet safety standards which is more of an abstract decision.For what it's worth, they sell those Aqara relays here, cheap too at 20 Euros or so. Of course we don't have to give a shit about regulations

author: liaifat85
author_rank: Regular Contributor
timestamp: September 12, 2023, 10:06:20 am
content: For smart home systems, I think Sonoff IoT switches are best.

author: rzyebay
author_rank: Newbie
timestamp: September 12, 2023, 10:42:00 am
content: These are not obtainable in AU market though. I can buy them on Amazon but unsure if they are compliant with AU Standard.If I install anything not compatible with AU standard in my circuit then home insurance would not compensate me if there is anything happen such as short circuit or fire or something.

author: Marco
author_rank: Super Contributor
timestamp: September 12, 2023, 12:22:25 pm
content: Oikotec sells them.
Using a Ikea Zigbee LED Dimmer as a PWM dimming source for another LED driver - Page 1
Forum section: electronics / beginners

author: Garywoo
author_rank: Contributor
timestamp: March 11, 2021, 07:13:04 pm
content: I have a LED ceiling panel light, and I'm trying to build a Zigbee controller for a PWM dimmable constant current LED driver, in order to dim it for use at my workbench.I have an old Ikea Tradfri LED driver lying around, and I knew that inside there were 2 distinct PCBs:The 24v power supply board is on the right in the picture above, and the Zigbee dimmer board is on the left. The power supply board wasn't going to be suitable for my light panel, as the Ikea driver is constant voltage, so I'm not using it in this project.The Zigbee dimmer part consists of a PCB to handle the LED dimming, and a white daughter board containing the Zigbee radio module and microcontroller. Here's a picture of the underside of the dimmer board:These modules have been fairly well documented, and I was able to locate the PWM output pin of the Zigbee module from information posted inthis instructable.I purchasedthis dimmable constant current LED driverto power my light panel. It accepts a few different forms of dimming control via the dim+/- inputs: PWM, 0-10v, and Resistance.I wired up the light panel to the driver, and then wired the PWM output from the Zigbee module to dim+ on the LED driver, and GND to dim-. I powered the Ikea module with 12v from an external supply, but ultimately plan to use the auxiliary 12v supply from the LED driver.When I turn on the AC to the LED driver, the light panel works and can be dimmed by controlling the Zigbee module, however the dimming seems to be somewhat offset. The driver output only turns on at about 40% brightness of the Zigbee module, and at 100% it's only drawing 640mA out of the available 750mA, which it should draw at full brightness.For what it's worth, I foundthison the PWM specs of the Ikea moduleHow can I get proper dimming control using the parts I have? Do I need adjust the PWM voltage level like in the instructable, or is the PWM output of the Ikea module just not the right frequency to work with the LED driver I have?
using a mechanical relay - Page 1
Forum section: electronics / beginners

author: Adhith
author_rank: Frequent Contributor
timestamp: November 30, 2017, 05:49:25 pm
content: hello everyone..I'm actually new to work with relay and AC power supply. I'm planning to drive a adenoidal valve which works on AC mains. I want it to be controlled using a 9V battery. So if I go for using mechanical relay how should be the connection?? also How should I connect the fly back diode??

author: retrolefty
author_rank: Super Contributor
timestamp: November 30, 2017, 06:17:48 pm
content: If your going to power the relay coil with 9 volt battery then the only real choice for a relay is a latching relay that draws coil power only during switching, not when steady on or off.

author: Old Don
author_rank: Regular Contributor
timestamp: December 01, 2017, 01:45:30 am
content: You'll need a relay with contacts rated for 250 VAC or more plus a coil that works on 9 VDC. (or maybe 6 to 12 VDC). With a latching relay you can use a SPDT momentary switch to toggle the relay. No flyback diode needed in that case. Only needed if driving it from solid state device.

author: danadak
author_rank: Super Contributor
timestamp: December 01, 2017, 11:45:19 am
content: If you are using a mechanical switch in lieu of transistor still usediode clamp.Regards, Dana.

author: perieanuo
author_rank: Frequent Contributor
timestamp: December 01, 2017, 07:59:44 pm
content: S202S12Envoyé de mon HUAWEI NXT-L29 en utilisant Tapatalk

author: Adhith
author_rank: Frequent Contributor
timestamp: December 01, 2017, 08:23:24 pm
content: my question is if A, B are the terminals of the diode and if A is fed with +ve supply and B -ve then how should I connect the diode??

author: Zero999
author_rank: Super Contributor
timestamp: December 01, 2017, 09:37:17 pm
content: Quote from: Adhith on December 01, 2017, 08:23:24 pmWhat do you mean? The terminals of the diode are anode and cathode, which is often abbreviated to A and K. The diode always goes in reverse parallel with the relay coil, with the anode going to negative and the cathode to positive. The reason for this is the diode only conducts, when the relay is turned off. When it's turned on, the diode needs to be reverse biased, so it doesn't pass any current.
Using a MOSFET to control a Buck module - Page 1
Forum section: electronics / beginners

author: Magnets
author_rank: Contributor
timestamp: March 11, 2016, 08:21:40 pm
content: I have one of these XL4005 buck modules to run an LED and want to control the module via a mosfet (RFP30N06LE).http://www.aliexpress.com/item/High-Quality-5A-DC-to-DC-CC-CV-Lithium-Battery-Step-down-Charging-Board-Led-Power/32388356240.htmlDo I need a diode across the buck to protect the mosfet or can I just run it like this with the buck in place of the bulb (3rd diagram)http://bildr.org/2012/03/rfp30n06le-arduino/Thanks

author: Simon
author_rank: Unknown
timestamp: March 11, 2016, 08:23:30 pm
content: you should not have problems and not need a diode if the buck converter is made properly

author: Magnets
author_rank: Contributor
timestamp: March 12, 2016, 07:42:12 pm
content: Quote from: Simon on March 11, 2016, 08:23:30 pmIs there anything critical or obvious that I could observe to determine if that's the case?Thanks

author: Seekonk
author_rank: Super Contributor
timestamp: March 12, 2016, 08:56:25 pm
content: I question the need for it at all. You could send a digital 5V signal through a diode and fake the feedback loop into thinking the output voltage is too high. That would shut down any type converter. If it is anything like the 2596, pin #5 is the shutdown pin. Raising it above ground will shut down the converter. This pin is fast and you could PWM the converter for variable intensity.

author: Magnets
author_rank: Contributor
timestamp: March 12, 2016, 11:27:44 pm
content: Quote from: Seekonk on March 12, 2016, 08:56:25 pmGreat point, the module actually has pads for pin 4 (EN) and ground pulled out which I never realised. It still uses 5.6ma when disabled, which I assume is the onboard LED.
using a Saleae Logic 8 with openOCD - Page 1
Forum section: electronics / beginners

author: kenn
author_rank: Contributor
timestamp: March 17, 2017, 01:46:38 pm
content: Has anyone done this before. I have an old Linksys board and I have soldered on a JTAG header, I am trying to experiment with openOCD and since my wife bought me a cool new Saleae logic 8 I assumed that was the best thing to use to interface with it however when I look at the pre-existing configurations that ship with openOCD I don't see one for the Saleae. I see a config for the chip I am trying to talk to (a Samsung s3c4510b01) but nothing for the interface.I should also point out that I very little experience with this and just doing some exploring, trying to read the flash if I can so any help would be great. Specifically how do I connect openOCD to the Saleae?Thanks

author: alm
author_rank: Super Contributor
timestamp: March 17, 2017, 02:24:59 pm
content: The Saleae Logic is a logic analyzer designed to only receive logic signals. I believe the Saleae software can decode JTAG, but this does not allow it to program something or perform a boundary scan. JTAG is a two-way protocol requiring both inputs and outputs. While it may be possible to use the Saleae Logic as a JTAG dongle with a custom firmware, this is not something that is built in either the Saleae or OpenOCD software, and I am not aware of such a project. There are various cheap JTAG dongles available, for example the FT2232 based ones and Versaloon, that should work out of the box with OpenOCD.
Using a scope to see one shot information - Page 1
Forum section: electronics / beginners

author: Szewczykm
author_rank: Regular Contributor
timestamp: January 21, 2013, 09:06:19 pm
content: I've got a Rigol 1052e and I'm trying to troubleshoot a problem I'm having using a serial DTR signal to reset an Atmel 328p (arduino) in order to program it.Using a FT232R breakout board from Sparkfun, it works fine.Using my own circuit with an FT232R IC, I can communicate with the chip, but with what seems like all of the same components, I can't get it to program.I know this looks like a microcontroller question, but really, it's a question about using my scope to analyze what's going on. Or, finding out if I'm just using the wrong tool for the job.So far I've used the scope to look a cyclical things like PWM and comparing one output to another. However, I'm trying to figure out how to capture something over time.The DTR pulse is a one shot thing. I want to see how the pulse compares between my circuit and the breakout board.Any advice on how to capture this one shot pulse? The next thing to look at would be to see how the pulse is timed with the transmission of data to the chip.Also, as an aside, any tips on probing a little SSOP chip? I have those clips you use for DIP packages to make clipping leads to the chip easier, do they make something like that for smaller chips?Thanks!Mike

author: Matje
author_rank: Regular Contributor
timestamp: January 21, 2013, 11:29:43 pm
content: Quote from: Szewczykm on January 21, 2013, 09:06:19 pmHmm, you have to capture one, export it as image, waveform or so, then capture the other, export it, then compare using some software - image viewer or what came with the device.Quote from: Szewczykm on January 21, 2013, 09:06:19 pmSetup the trigger, set the scope to "single mode" (see manual, page 2-38 in my PDF), press "Run" and it should be there. It helps a lot to play around with the scope and all the stuff in the menus before trying something serious...To see the timing between DTR and the data line use both channels, trigger off of DTR.Quote from: Szewczykm on January 21, 2013, 09:06:19 pmI think there are such devices, you probably wouldn't like the price tag.Easiest way would be to temporarily solder a short piece of blank wire to the pin of interest and clip to that.

author: Unknown
author_rank: Unknown
timestamp: January 21, 2013, 11:58:52 pm
content: Quote from: Szewczykm on January 21, 2013, 09:06:19 pmThey do. As Matje already mentioned, be prepared for the sticker shock. I've seen some of them going for tens of dollars each. Sigrok published anice comparison(scroll down to 'high-end probes' for the one capable to go down to ~0.5 mm pitch. The TPI ones are somewhat affordable. The Electro-PJP ones (also sold by Pomona) use a non-standard 0.8 mm pin connection, as opposed to the standard 0.025" pins.

author: Smokey
author_rank: Super Contributor
timestamp: January 22, 2013, 01:02:02 am
content: Little pieces of wire wrap style kynar wire soldered to the pads make great clip points. Everyone should have a spool of that stuff around for mods anyway.
Using a signal generator as a voltage sink - Page 1
Forum section: electronics / beginners

author: BStanley346
author_rank: Newbie
timestamp: January 13, 2021, 03:59:30 am
content: I am trying to reverse engineer the expected frequency for a few gauges in my car. The cluster computer is fed 12VDC and circuits are grounded via sensors at random frequencies which are interpreted by the computer and displayed. I have a spare gauge cluster, power supply, and signal generator and I am wondering if the signal generator can be used as a voltage sink to trigger the logic? Would I need to set up a high-frequency relay of some sort or is this something that a signal generator should be able to handle? I know that these signals are typically tied straight to ground so there would be built-in resistors to keep the current low but I have no idea what the expected draw would be. I am using a Koolertron 60MHz signal generator (can be found here for more datahttps://www.amazon.com/gp/product/B073P6TKQC/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1).Thank you in advance.

author: WattsThat
author_rank: Frequent Contributor
timestamp: January 13, 2021, 05:29:16 am
content: Signal generators are voltage sourcing devices, it appears the device in question can generate up to 20 volts peak to peak. That is usually into 50 ohms but who knows, the specs are a bit dodgy.If the gauge supplies voltage that needs to be pulled to ground to generate a low pulse, that can be achieved with an NPN transistor with it’s base driven through a resistor from the generator output.It would be most useful to scope what’s going on in a working system/car to know what amplitude and frequency signals are needed.

author: radiolistener
author_rank: Super Contributor
timestamp: January 13, 2021, 05:42:51 am
content: Yes, you can use it. But you're needs to use CMOS waveform, because standard Sine/Square/Ramp/etc waveforms use oscillation around zero.For example if you use Sine waveform and setup amplitude 5 Vpk, you will get voltage change from -5 Vpk to +5 Vpk. -5 Vpk is not safe for logic input and even can destroy it. This is why you need to use CMOS wavform, which produce square wave above zero (for amplitude 5 Vpk it will be from 0 Vpk to 5 Vpk).Also you're needs to check required logic volatage and setup amplitude properly.

author: james_s
author_rank: Super Contributor
timestamp: January 13, 2021, 07:15:54 am
content: If I understand what you're trying to do, all you need is a NPN transistor and base resistor or N channel mosfet. Drive the base/gate with the function generator, ground the emitter/drain and connect the collector/source to your cluster. When the output of the signal generator goes high, the transistor will switch on and pull the line to ground.
Using a sinewave OCXO as a timer input source - Page 1
Forum section: electronics / beginners

author: g0mgx
author_rank: Regular Contributor
timestamp: April 30, 2020, 12:58:21 pm
content: Hi GangI want to use a 10 MHz OCXO oscillator as an input to a STM32 clock; the oscillator swings +/- 2V and I need to convert this to a square wave 0-3.3V.I've tried using a simple comparitor but the circuit fails over about 1Mhz, I've tried a simple transistor switch feeding a 74HC04 gate x 3 but still there is a lot of junk in the output signal.Can anyone suggest an easy way to convert my sine wave into a logic level square easily?I'm struggling with what should be a very simple circuit.Many thanksMarkG0MGX

author: Manul
author_rank: Super Contributor
timestamp: April 30, 2020, 01:34:03 pm
content: The simplest what comes to my mind (may not be best, but should be ok). I assume you need 3.3V logic out. Notice a schmitt trigger input inverter. You can choose freely (but it needs to be fast enough), for eg. SN74LVC1G14.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 30, 2020, 01:39:44 pm
content: Are you sure you need a square wave?Virtually all uC's are designed to run from a crystal, and have therefore already the circuitry inside to run from a sinewave.Go read the datasheet of your STM32 again and look at the different options for the clock input.

author: g0mgx
author_rank: Regular Contributor
timestamp: April 30, 2020, 01:42:52 pm
content: Thanks - I'll look at the datasheet again - a riveting read.How worried do I need to be about the logic level? THe sinewave is +/-2V and the TIM input is 0-3.3V?Mark

author: g0mgx
author_rank: Regular Contributor
timestamp: April 30, 2020, 01:43:39 pm
content: Thanks.Is that LTSpice? I keep seing this again and again - must read up.Mark

author: Manul
author_rank: Super Contributor
timestamp: April 30, 2020, 02:15:38 pm
content: Quote from: g0mgx on April 30, 2020, 01:42:52 pmSo you want this 10Mhz for clock or timer input? Anyway, yes, you should worry about levels, to not hit negative or positive above Vdd.If you plan to run a coax from 10Mhz source or there will be considerable distance you should also take care about impedance matching.

author: g0mgx
author_rank: Regular Contributor
timestamp: May 01, 2020, 01:23:26 pm
content: Quote from: Manul on April 30, 2020, 02:15:38 pmYes indeed, I'm trying to teach myself STM32Cube programming (having migrated from STM32 on Arduino) - I am trying to write an algorithm to discipline the OCXO from a 1PPS GPS signal.Its just a technical learning exercise but kind of fun.Mark
Using a SMU as a variable resistor/How to DIY a 1A potentiostat? - Page 1
Forum section: electronics / beginners

author: jogri
author_rank: Frequent Contributor
timestamp: August 23, 2020, 07:23:30 pm
content: Hi guys,is it possible to use a SMU to remotely control a power supply that correlates a resistance to a voltage? The power supply is outputting a fixed current of 1 mA (on the remote programming port) and is meant to be connected to a resistor (1 kper V) to control the output voltage. Am i missing something obvious or can i just hook up my SMU and tell it to sink the equivalent of 1k* 1 mA (if i want 1V)?Why would i even do that when i have a SMU? I need an output current of 1 A, and my Keithley 236 can only deliver 100 mA. My Power Designs 2020 on the other hand can output 2 A, and its output voltage can be controlled remotely (and i can switch the polarity of the output with my 34970 and a few relays).What do i want to do with it? Use it for cyclic voltammetry, that means creating voltage vs current plots in the range of +/- 5V. The voltage is applied in the form of a triangle wave (@ a few Hz), the current is measured simultaneously and plotted against the voltage. I am currently just cranking the voltage up and down manually, but this is less than ideal since there is a lot of time for electrolysis to happen (we are talking about 10 min per cycle).Alternatively, can you recommend a circuit design that can output a +/- 5V signal @1 A? Normal DIY potentiostats just use the output of an op amp since they rarely need more than 1 mA, but since i also need a negative output voltage i can't just use the opamp to drive a transistor that can handle this current (i'm probably missing an obvious solution).(For anyone wondering why i need 1 A for a CV: I am working with molten salts, and they are rather good conductors...)

author: julian1
author_rank: Frequent Contributor
timestamp: August 23, 2020, 10:14:10 pm
content: Use a signal generator for a -5 to +5V ramp, add a bipolar push/pull emitter follower for 1A, then add a current sense resistor, and plot current against voltage on a scope? Anything more complicated, and you begin to replicate the smu function.
Using a spectrum analyser to see if a low frequency TX signal is clean? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: April 25, 2016, 02:03:50 pm
content: I am not very good with spectrum analysers, so need to ask for advice. I want to look at my signal on 137 kHz (UK LF ham band) from my amp in real time, into my real antenna, not a dummy load. So I stuck a small rubber duck antenna into the input port, with no DC block as some have attenuation on lower frequencies I believe.I then transmitted WSPR2 into my real antenna. I see the signal on the SA and played with bandwidth settings. What I am unsure about is how much signal strength do I need to capture? The TX will run 1kW into a dummy load, no problem, but antenna efficiency is of course pitiful on LF given what any normal person can erect. If I hold the rubber duck when TX'ing some sidebands show, well down, but hardly anything if I don't "help" the rubber duck. How do I decide on and acquire enough signal please?I have some screen shots of my signal on local LF grabbers, and on the SA. The scope shot is via a "scopematch" where the 2 traces show V / I balance as being near perfect, so the matching into the external loading coil and antenna is excellent. The amp's meter shows near zero reflected power. I *THINK* all looks OK now?I have had a recent report of a very dirty signal filling the WSPR waterfall from 2 UK stations. I have run this thing for 18 months with good reports, so something recent has occurred, and I found the sound card level from WSPR to my Kenwood TS-590 exciter had mysteriously changed to maximum. Re-setting it gave a clean sine wave from the pre amp into the main amp. With too much drive into the pre-amp it was a very distorted output. The screen shots show things after I reset the drive level correctly.I think I have it sorted, but my lack of SA technique causes me a little doubt. Thanks for looking!The screenshots are athttp://www.chriswilson.tv/signals/signals.htmland athttp://www.chriswilson.tv/signals2/signals2.html

author: Paul Price
author_rank: Super Contributor
timestamp: April 26, 2016, 04:06:38 pm
content: You only need to capture enough signal strength to give you something like a 2:1 ratio above the "mud." noise floor.Anything more is not needed, just a scaled up sample.
Using a subminiature magic eye tube as an audio spectrum visualizer - Page 1
Forum section: electronics / beginners

author: Maliaris
author_rank: Newbie
timestamp: May 22, 2021, 09:13:58 pm
content: Hello eevblog ,I am trying to build a crude mono audio spectrum visualizer using a DM71 (http://www.r-type.org/exhib/abc0007.html)sub-miniature magic eye tube. So far i have come up with the below schematichttps://imgur.com/a/LKJW20cI plan to power all modules using a laptop power supply at 19v 3A, and step down the voltage for the op amp circuit using an lm317 dc to dc boost converter and a NCH6100HV High Voltage DC Step Up Converter for the 90v plate potential needed for the DM71, at last i plan to use a AA battery to power the heater filament due to the tube having a directly heated cathode.At the values that i plan to drive the tube with a grid bias of -5v, when no audio signal is present the column should be at half length,when a audio signal if fed to the grid column should change in size according to the signal voltage. The audio signal after being amplified using the op amp should peak at +5v / -5v which in turn will max the length of the column or extinguish it completely respectively. I have simulated the op amp circuit and the ne555 negative voltage generator using Ltspice and they seem to work as intended, though i had no luck trying to simulate a triode similar to the DM71, so I'm not sure if i biased the grid correctly or if the use of a battery is correct on a directly heated cathode. Can you spot any glaring issues with the above circuit?I would appreciate any input on how i could correct or improve the project.Thanks!

author: TimFox
author_rank: Super Contributor
timestamp: May 22, 2021, 09:20:44 pm
content: Is that 90 V supply permanently grounded? At the very low plate current of the tube, and the modest current requirement of the negative voltage for the op amp and grid circuit, a simple resistive voltage divider "ground splitter" would suffice, perhaps using a lower current op amp.Or, you could float the cathode on a 10 V Zener and power the op amp from it to eliminate the DC-DC converter circuit. This should simplify the circuit immensely.

author: Maliaris
author_rank: Newbie
timestamp: May 22, 2021, 10:06:42 pm
content: I hadn't thought of using the 90v to power the op amp. So i create a voltage divider and use it(+45v) as virtual ground for a suitable op amp elimination the boost converter and the negative voltage generator, neat! I will play around in ltspice with both recommendations. Thanks for the advice!

author: TimFox
author_rank: Super Contributor
timestamp: May 22, 2021, 10:36:48 pm
content: You need to drive the grid to at most maybe -10 V from the cathode, so a mere -15 V voltage divider (resistors or resistor-zener) would do, since there is no actual reference voltage in the circuit. The response of the eye tube will change a bit with its plate-cathode voltage, so take that into account when designing the divider.
Using a switched power barrel jack to select source - Page 1
Forum section: electronics / beginners

author: ralusp
author_rank: Newbie
timestamp: February 10, 2024, 08:59:27 pm
content: Hi all, I'm prototyping something which could be powered from a 30VDC battery or 24VDC power barrel jack. I'm trying to find the simplest way to take power from the power jack if present, otherwise draw from the battery. It seems like a switched power jack is ideal for this. Whichever source is selected would then feed into a DC/DC converter module that provides a consistent stable rail for the system. These are discrete components connected via wire, not a PCB. All of the components are selected, and I'm trying to ensure I wire it correctly.I'm confident the center pin of the power barrel goes to the DC/DC VIN terminal, the shell of the barrel goes to the DC/DC GND terminal, and the switch lead for the barrel is attached to the battery return (switch is normal-close). So when a plug is inserted it breaks the battery return's circuit. I'm less sure how to tie the battery positive into the system - I believe it would also be connected to the DC/DC VIN terminal. But should I use a diode? If so, how do I select the right type and parameters? And what's the best way to incorporate one into a wired circuit - just solder a through-hole component inline?Thanks.

author: SuzyC
author_rank: Frequent Contributor
timestamp: February 10, 2024, 09:33:58 pm
content: Just use a diode in series with the plus of the 24-V power source, anode of the diode connects to the 24-V source.Use a barrel connector to apply the 30V power source. When the 30-V power source is connected by the barrel connector the diode will disconnect the 24-V power source. Tie the negatives of the power sources together. For lowest power loss, use a Schottky diode rated a high enough current and voltage handling>40V. For 3-amps 1N5822.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: February 10, 2024, 10:18:40 pm
content: The top left corner of this schematic has an answer. This is the Sparkfun ESP32 Thinghttps://cdn.sparkfun.com/assets/learn_tutorials/5/0/7/esp32-thing-schematic.pdf

author: golden_labels
author_rank: Super Contributor
timestamp: February 10, 2024, 10:37:20 pm
content: Using a solid state solution has an important advantage here, compared to mechanical switching. 24 V is enought to cause sparks.

author: langwadt
author_rank: Super Contributor
timestamp: February 11, 2024, 12:26:29 am
content: how much current?

author: ralusp
author_rank: Newbie
timestamp: February 11, 2024, 01:14:46 am
content: Thanks for the responses - I'm still digesting the suggestions. System load is 1.5A at 24VDC.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: February 11, 2024, 11:18:53 pm
content: Make sure you consider reverse polarity, and what happens if someone plugs in an AC wall wort.
Can i use a tx2-rx2 ic pair with a standard 433Mhz rf receiver/transmitter? - Page 1
Forum section: electronics / beginners

author: bodanila
author_rank: Newbie
timestamp: May 08, 2015, 12:51:10 pm
content: Hello im new in electronics and i have a question if i can use the standard 433Mhz rf moduleshttp://www.seeedstudio.com/depot/433Mhz-RF-link-kit-p-127.htmlwith the 5 function radio control ic pair datasheet:http://www.instructables.com/files/orig/FWW/CD13/GV525G0X/FWWCD13GV525G0X.pdf.
Using a USB-C Hub chip, Any Gotchas? - Page 1
Forum section: electronics / beginners

author: TinyMirrors
author_rank: Contributor
timestamp: August 14, 2019, 03:41:51 pm
content: So I want to reduce the number of USB cables to a board from 3 to 1. The devices are a microcontroller, a jtag programming chip, and an external camera. I need to be able to use USB 3.1 speeds for the camera. The connectors are USB-C.I'm attempting to use TUSB8042Ahttp://www.ti.com/product/TUSB8042Aas the hub chip which then communicates to all the other chips for me. I plan on keeping the USB traces in that area of the PCB only and keeping them pretty short and the same length.Are their any other words of wisdom I should know about before attempting a board like this? I've attached a simple drawing.- Just learned that the male side USB-C connectors all require a 0.8mm pcb.

author: DEV001
author_rank: Contributor
timestamp: August 15, 2019, 08:45:25 pm
content: This application note has some good information on USB 3.0 PCB layout guidelines.http://www.ti.com/lit/an/spraar7h/spraar7h.pdf

author: TinyMirrors
author_rank: Contributor
timestamp: August 15, 2019, 09:24:01 pm
content: Thanks for the guide. Really useful!
Using a woodshop air filter as a fume extractor. - Page 1
Forum section: electronics / beginners

author: jgalak
author_rank: Regular Contributor
timestamp: November 27, 2017, 03:16:05 pm
content: A while ago, someone gave me an unbranded woodshop air filter. Looks just like this one:https://www.ebay.com/itm/Portable-Air-Filter-with-Dual-Fans-115-Volt-0-4-Amp-X2-60HZ-140605-/282255189230?hash=item41b7b864ee:g:-aQAAOSw4GVYKRZU(which also seems identical, except for branding, to a Grizzly G9955 -http://www.grizzly.com/products/Benchtop-Dual-Fan-Dust-Filter/G9955?utm_campaign=zPage&utm_source=grizzly.comor a PSI DC725 -https://www.pennstateind.com/store/DC725.htm)I'm wondering if I can add or replace the filter with one suitable for solder smoke. If so, what's the right filter? A link to a source (US) would be appreciated.Related question: would a solder fume extractor (either the retrofit above, or a "real" one) filter 3D printing odors? I print in PLA, so it's not toxic, but my wife hates the smell of the melted plastic. Advice on filter types for this task would also be appreciated. Yes, exhausting outside would be better, but that's a bigger project.Thanks.

author: Gyro
author_rank: Super Contributor
timestamp: November 27, 2017, 03:32:14 pm
content: An Automotive cabin/pollen fiter would probably be your best bet - as long as it's one of the activated carbon ones. Alternatively an activated carbon cooker hood filter, an activated carbon one again, the sort that are used in recirculating filters.I haven't tried either option though.

author: cdev
author_rank: Super Contributor
timestamp: November 28, 2017, 12:42:46 am
content: A heat recovery ventilator (HRV) can exchange polluted air for fresh outdoor air warming or cooling the incoming air with the outgoing. They will actually get rid of the toxic fumes outdoors.VOC removal is ineffective using most "activated charcoal" filters. That is what i've been told by both scientists and indoor air specialists. Most filters are mostly jst particulate filters because their ability to remove VOCs from air just doesn't last very long. Maybe a few days after being unwrapped.
Using AC terminal blocks on DC project. - Page 1
Forum section: electronics / beginners

author: rickey1990
author_rank: Regular Contributor
timestamp: July 01, 2022, 10:37:49 pm
content: Hi I am currently in the design phase of a "Micro" solar junction board/ distribution box for 12v DC. The board will feature a 12v 20a non fused terminal for kettles and a 20a fused side (25A Fuse) with 4 10a pluggable 5.08mm connectors.I have picked out some connectors PCB-8 / K14 , for the power in and kettle out. They say they are rated 40A but there's not really much info on them. Would anyone know the maximum amps at 12v or have used them before.Also I had a look at some images of 60A solar charge controllers but to me they look alot like the 5.08mm 300v 10A terminal blocks. Obviously 12@10a is 120W , 300v@10a is 3000W. But I assume there's some sort of rule when using them for DC. Or is it as simple as saying you can run 3000w at 12v through it.Kind regards ,Rick

author: BrokenYugo
author_rank: Super Contributor
timestamp: July 02, 2022, 02:31:27 am
content: Amps are amps for the most part. AC/DC ratings are for things like switch and relay contacts.

author: WattsThat
author_rank: Frequent Contributor
timestamp: July 02, 2022, 02:55:25 am
content: QuoteNo. 10 amps is the limit, not 250 (3000/12). AC or DC does not matter for a non-switching device, amps are amps as the previous posted stated. Think current = heat.

author: rickey1990
author_rank: Regular Contributor
timestamp: July 03, 2022, 03:14:24 pm
content: Okay thankyou for your both your responses 😊.

author: exmadscientist
author_rank: Frequent Contributor
timestamp: July 04, 2022, 08:43:30 am
content: Part of the reason you see terminal blocks marked as "AC" or "DC" is that the clearance (spacing) rules are different for AC compared to DC. So when they test and certify it, they need to tell you not just the test voltage but the type as well. If you are truly (extra) low voltage you can safely ignore all of this.

author: Jeroen3
author_rank: Super Contributor
timestamp: July 04, 2022, 09:40:24 am
content: In you image, the left one is good for "a few amps", say max 5A. Or peak up to 10A at 25c ambient temp for a high-end brand.The right one can take more current, say 10A over the full temperature range. But only if you can mount it properly. Note that there will be mounting stress on the pcb junctions, and you're dependent on the crimp quality for the generated heat in the junction as well.You can get the same type of green plug in terminal blocks, but with flat inside connectors, that can take up to 30A for reputable brands.For example Phoenix Combicon Power (PCV).In these instances you need to pay attention to the derating factors. For ambient temperature and parallel conductors.This matters when you're going near the "advertised" maximum rating.If those details are unavailable, the part is probably not suitable until you've done your own qualification.Remember ohms law: P = R * I2
Using ADC input pins to route vcc - Page 1
Forum section: electronics / beginners

author: amateur_25
author_rank: Regular Contributor
timestamp: May 06, 2012, 12:12:03 am
content: HiI trying to layout my own pcb based on someone elses schematic. Due to how the board is laid out, it easier to use one of the extra ADC pins avaible on the TQFP package to forward pwr onto the right hand side of the board. The datasheet says it only functions as an ADC input. Am I correct in saying it's safe to do so?I'm using pin19 on the 328P TQFP.

author: Psi
author_rank: Super Contributor
timestamp: May 06, 2012, 12:24:48 am
content: Do you mean you need to get VCC from one side of an IC to the other and you're asking if you can go "through" an unused input pin?

author: vk6zgo
author_rank: Super Contributor
timestamp: May 06, 2012, 04:36:58 am
content: I don't know the device,but it sounds scary as hell to me!

author: T4P
author_rank: Super Contributor
timestamp: May 06, 2012, 05:39:30 am
content: Does a 328pin TQFP even exist

author: TerminalJack505
author_rank: Super Contributor
timestamp: May 06, 2012, 06:00:03 am
content: I'm guessing that he is saying that he is going to route to the Vcc pin as well as the unused ADC pin.I don't see why you couldn't do this. It is an input pin, after all.Quote from: Dave.S on May 06, 2012, 05:39:30 amLOL. I'm pretty sure he's talking about the "Arduino chip."Aka Atmel ATmega328P.

author: Psi
author_rank: Super Contributor
timestamp: May 06, 2012, 07:40:49 am
content: You just have to route it so any voltage drops in vcc tracks don't result in a higher voltage on the input pin than the actual VCC pin.Or it will feed backwards into the chip from the IO and may cause problems.It's not an issue unless you happen to be powering something else from in between the vcc<->inputpin link.
Using Amprobe 320 and In-rush current vs Peak hold (Crest)  - Page 1
Forum section: electronics / beginners

author: dylanmitchell
author_rank: Contributor
timestamp: December 18, 2020, 10:05:05 pm
content: I got an Amprobe 320 so I can measure in-rush (AC only) and DC current for automotive troubleshooting. I have a Fluke 323 but it doesn't do in-rush or DC and is a much simpler meter. If anyone's familiar with the 300 seris and has tips, please share them. I'm only using the meter for current, I have a Fluke 117 DMM too.I've started with AC current and the auto and manual current measurements. It will also show Hz through the clamps. PEAK-RMS mode (in-rush current) is a great feature but I'm not sure how accurate is compared to a Fluke 902 or 370s series. Testing on shop vac showing 39 A in rush, 24 A max, and dropped to steady 12 A. I'll mainly be using the meter for load calcs making sure I'm circuits aren't overloaded.Also, what is PEAK-RMS mode (in-rush current) vs Peak hold (Crest)? My 320 doesn't have Peak hold, but it's mentioned in the manual in reference to the 320.To measure AC or DC current:1. Turn the rotary function switch to or .2. Press SELECT button to choose measurement function (AC A, DC A,DC+AC A, or Hz). The display reflects the chosen function mode.3. Open the clamp by pressing the jaw release and insert the conductor tobe measured into the clamp. Ensure the jaws are firmly closed.4. Close the clamp and center the conductor using the jaw alignmentmarks.5. View the current reading on the display.6. When measuring AC or AC + DC current, press SELECT button to viewthe frequency reading on the displayTo measure AC or DC low-current for small conductors:1. Turn the rotary function switch to or .2. Press SELECT button to choose measurement function (AC A, DC A,DC+AC A, or Hz). The display reflects the chosen function mode.3. Open the clamp by pressing the jaw release and insert the conductor tobe measured into the clamp. Ensure the jaws are firmly closed.4. Align the conductor at the specified jaw tip area for low-currentmeasurement5. View the current reading on the display.6. When measuring AC or AC + DC current, press SELECT button to viewthe frequency reading on the display.REC / PEAK-RMS Press REC button to activate maximum, minimum andaverage reading memory mode ( MAX MIN AVGis displayed). The meter beeps when MAX and MINreading is updated during measurement. Press RECbutton again to read the MAX, MIN and AVG readingin sequence. Press REC button > one second to exitMAX/MIN/AVG reading memory mode.Press REC / PEAK-RMS button > one second to enterPEAK-RMS mode ( is displayed) to captureinrush current or voltage RMS values (80 ms). Press asecond time > one second to exit.(330 only)Hz / CREST Press Hz button to activate frequency measurementmode. Press a second time to exit.Press REC button > one second to activate CREST mode(5 ms) to capture current or voltage peak values (MAX is displayed). Press again to toggle betweenMAX and MIN. The meter beeps when MAX orMIN reading is updated during measurement. PressCREST button > one second to exit CREST mode.Note: Auto Power Off is automatically disabled underCREST modes.
Using an arbitrary waveform generator to output composite video signal - Page 1
Forum section: electronics / beginners

author: JustAnotherGuy999
author_rank: Contributor
timestamp: February 27, 2016, 12:15:45 am
content: for example: can we play around with an arbitrary waveform generator to create a waveform that outputs a "point" with a certain color in a certain position to a tv (through a yellow RCA connector).

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 27, 2016, 12:24:48 am
content: It seems unlikely with most common AWG.A composite analog TV signal is at least 3 different arbitrary waveforms:1) The actual lines of video signal that are visible on the screen.2) The horizontal sync interval between the lines.3) The vertical interval sync signals between the video frames.And there are actually several different kinds of vertical interval lines.The entire waveform for a composite frame for a color video is quite large and almost certainly exceeds what an AWG could create.And if you limit "waveform" to a single line of video, then you must accommodate more than one kind.And I don't think most AWGs will handle that, either.

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 27, 2016, 12:30:27 am
content: OTOH, you could use something like a Raspberry Pi to generate video signals rather easily.And you could buy dozens of them for what even a cheap AWG would cost.

author: JustAnotherGuy999
author_rank: Contributor
timestamp: February 27, 2016, 12:35:45 am
content: thanks

author: uncle_bob
author_rank: Unknown
timestamp: February 27, 2016, 12:40:12 am
content: HiA good old analog TV set will not do much of anything with a single line of video. About the most simple is the old NTSC waveform that is essentially two frames that interleave. You get a full frame every 1/30 second. The signal can be looked at a number of ways and you get a different bandwidth each way. Just to move things on, let's say it's a 4.5 MHz bandwidth That gets you to something more than 9 mega samples per second. It would take a generator that will do a 100K sample run to do that.Now, since it's an analog signal, you would need a very good lowpass filter between the generator and the TV. A more realistic setup would be about 20 mega samples per second and a somewhat easier to build filter. At that point you have a 200K sample generator. If you want to do it with the generator here on the desk and not play with a filter, you need to run a few mega samples through it. Oddly enough that's a bit more than this one will do.Consider that none of this is actually synthesizing the waveform. All you are doing is playing back a digitized video signal. The only way you set it up is to do creative software to produce the file. You then just us the generator as a fast ADC to play your file. A $30 video card is a much easier solution.Bob