hybridfree/eevblog-posts huggingface dataset:
Philips PM3350 Oscilloscope Value - Page 1
Forum section: electronics / beginners

author: SaabFAN
author_rank: Frequent Contributor
timestamp: March 29, 2015, 08:52:56 pm
content: Hi,I'm planning to debug a Maximum Power Point Tracker and a Atmega-Based computer for a sailing-boat which I designed as basically my first real electronics project (up to now, I only have done stuff with the Arduino).For that project I'm currently eyeing a Philips PM3350 as an interim-Solution until my Rigol DS1054Z arrives (Batronix says End of April, but the PCBs arrived last week^^).Is anyone here with some experience with that device? And how much is it worth (roughly)?Or is there a better solution? The market here in Germany is pretty thinned out currently when it comes to Oscilloscopes by the way. Even defective analog scopes never sold below 70€ on ebay during the last 2 weeks and I am studying Game Art, so University-Lab to raid

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: March 29, 2015, 09:07:34 pm
content: The PM3350 oscilloscope is nice but bulky (I have the PM3355 which should be close), but it is bulky.Why dont you find someone who will lend you an oscilloscope for a month. Alternatively, you could considerbuying a logical analyser ( a salae clone for example) that will be complementary to your Rigol1054Z.like this one (i did not check, just searched on amazon.de)http://www.amazon.de/Saleae-Analyzer-8Channel-saleae-support/dp/B00DPCDEV2/ref=sr_1_1?ie=UTF8&qid=1427663130&sr=8-1&keywords=saleae+logic+analyzerBut beware that they actually have it in stock in Germany, otherwise they may order it from China and it will take more thanone month.
"Phoenix" 0.2" terminal plugs without locking ramp/arm? - Page 1
Forum section: electronics / beginners

author: incf
author_rank: Frequent Contributor
timestamp: April 28, 2025, 10:38:29 pm
content: I've seen products that won't accept terminal plugs with the locking ramp circled in red.Does anyone know where to find terminal block plugs that lack the locking ramp? (ie. what company and product family)Do they fall out more easily if they lack the locking ramp?For commercial product.Couldn't find it in some of the 'cheaper' catalogs like LCSC.
Phoenix Contact Power Supply & UPS Connection - Page 1
Forum section: electronics / beginners

author: SG-1
author_rank: Regular Contributor
timestamp: May 20, 2019, 08:22:23 pm
content: I have a Phoenix Ultra Cap 20kj module & a Phoenix Quint UPS. Both modules has a terminal marked with a square wave symbol. Both modules have two other terminals marked + & - for the DC input or output.What is the third terminal marked with the square wave for ?https://www.phoenixcontact.com/online/portal/us?uri=pxc-oc-itemdetail:pid=2320380&library=usen&tab=1Click on Technical then block diagram.

author: Bratster
author_rank: Frequent Contributor
timestamp: May 21, 2019, 07:41:30 am
content: According to the manual on the page you linked it appears that is a communication wire between the UPS module and the battery module.That is my conclusion based on the system apparently having a smart battery and the only wiring photo shown is just power, ground and the square wave wire connecting the UPS module to the battery module.But the manual doesn't outright say that, or even show any real wiring diagrams for that matter.So I could be totally wrong haha.Sent from my Pixel 2 XL using Tapatalk

author: SG-1
author_rank: Regular Contributor
timestamp: May 21, 2019, 12:11:36 pm
content: Poor documentation for sure. Could it allow the power supply to operate in flyback mode ?Is there any particular Greek letter that is now used for flyback ?
Phone's touchscreen goes awry when connected to a certain charger - Page 1
Forum section: electronics / beginners

author: Alison
author_rank: Newbie
timestamp: November 04, 2013, 12:13:28 am
content: Hello everybody,I recently bought this neat power station with four mains outlets and three USB that plugs right into a normal duplex wall plate.I can charge my Nexus 7 off the USB ports just fine, but when I plug my Nexus 4 in the touchscreen goes slightly awry and randomly misses touches.Could this be due to a high frequency crap on the DC output? Would I fix this by replacing the output capacitors with higher valued ones? Unfortunately I don't have an oscilloscope so I can't see how noisy the outputs areThanks!

author: Rigby
author_rank: Super Contributor
timestamp: November 04, 2013, 12:32:17 am
content: I've had that happen when the wattage isn't sufficient to both run the device and charge it. The charge indicator would cycle on and off at about 1Hz.Most USB chargers can deliver 5W of power, but few are rated for 10W, which some devices require.I would check the ratings on the chargers that came with the devices and see if the new wall outlet thing can deliver the required power.

author: echen1024
author_rank: Super Contributor
timestamp: November 04, 2013, 02:45:24 am
content: No, simply not enough wattage.

author: Alison
author_rank: Newbie
timestamp: November 04, 2013, 03:55:45 am
content: Yep, my phone acts totally normal when it's the only thing plugged into the outletthingy's usb ports. I'm disappointed because my old USB outletthingy could charge my phone and tablet at the same time with no ill effects and was also rated at 2.1A.I don't think it is worth to return the new outletthingy, I'll just live with it I guess.

author: amyk
author_rank: Super Contributor
timestamp: November 04, 2013, 06:20:36 am
content: Maybe it lies about its current rating...

author: tan98010
author_rank: Contributor
timestamp: November 04, 2013, 06:37:25 am
content: It is most likely there is a AC leakage, i faced this problem before, i solved the problem by grounding the negative at the DC to the mains ground.

author: DavidDLC
author_rank: Frequent Contributor
timestamp: November 04, 2013, 08:32:19 am
content: That is because it is a noisy chargerIt happens with different chargers, different phones, that is why manufacturers recommend you to use approved chargers only.David.
Phones systems & passive tapping of twister pair - Page 1
Forum section: electronics / beginners

author: Whales
author_rank: Super Contributor
timestamp: December 22, 2018, 10:59:18 am
content: I have a network closet with mostly a tangled mess of ethernet and some occasional phone lines woven in (some PBX, some POTS). I want to untangle it all and properly separate & clearly label the POTS lines, especially since it looks like one might currently be plugged into a gigabit switch.Yeah.I'm looking forward to finding out for sure. Let's hope it's not.At the moment my plan is to spend a few hours with an old landline phone IDing the pots lines and labelling them with their phone numbers. Whilst I can deal with the ethernet mess, I'm not a phone tech.Q1. Any interesting phone-related resources that are suggested reading?I'm familiar with what a ringing voltage is and how I don't have perms to do anything past that plug; but I've never read any formal sources of info.For example: Are there relevant publicly-available walls of advice or standards for POTs in network cupboards? Eg minimum protection reqs, cable routing reqs, etc. At the moment my searches are returning pictures of crockery in drawers.Q2. Are passive twisted pair taps for phone/audio freqs a product that exists?EDIT: to be clear, not a wired splitter. I'm imagining 0-8KHz audio (intrinsically AC coupled) taps, using a short coil pickup you place near the cable or a capacitive pickup/probe on the cable jacket. Twisted pair isn't infallible, esp at close range, but I can't find even a tiny bit of literature about the idea using my current search terms.This last one is out of curiosity. Using an actual plug-in phone is good enough for what I want to do, but I thought I can't be the first person to think of "truly" passive phone tapping.

author: soldar
author_rank: Super Contributor
timestamp: December 22, 2018, 12:24:17 pm
content: Pots identification is simple and straightforward. Just connect a phone set with alligator clips or any other way. Even if you do not have a phone set you can just measure voltage because it will be about 48 Vdc when the phone is on hook and fall to a few volts when the phone is off hook.

author: Whales
author_rank: Super Contributor
timestamp: December 22, 2018, 10:18:35 pm
content: Thanks for the tip.I presume most old-fashioned PBX systems also provide phantom power, so the handsets don't need any other wires/plugpacks to work, so I'll still have to do other checks to ensure I'm not chasing the wrong system.
Phono output on TV - Page 1
Forum section: electronics / beginners

author: chagli
author_rank: Contributor
timestamp: April 06, 2019, 11:19:16 am
content: Hello,I would like to plug a headphone on my TV without disabling the buit-in loudspeakers.The conventional headphone output doesn't work without disabling the sound so I tried the phono output. Obviously, this output is not designed to drive a headphone because the level was too low.I thought I could add a small amplifier and then plug the headphone.But I don't know the voltage level and the output impedance of such an output.Do you think it will do the job and have you any idea of the specs of this output ?Thank you !

author: stj
author_rank: Super Contributor
timestamp: April 06, 2019, 11:34:13 am
content: phono levels are sort-of standardised.i think it's 500mV 10kbeen a long time since i did audio work, so you may want to double-check that.

author: soldar
author_rank: Super Contributor
timestamp: April 06, 2019, 11:44:46 am
content: Have a look at the circuit in page 12 ofhttps://datasheets.maximintegrated.com/en/ds/MAX9725.pdf

author: chagli
author_rank: Contributor
timestamp: April 06, 2019, 12:01:07 pm
content: Thanks !
Photo Diode, or Photo Transistor? - Page 1
Forum section: electronics / beginners

author: TheKraken
author_rank: Newbie
timestamp: July 11, 2013, 04:07:44 am
content: I have not quite been able to figure out what it is that I would need specifically, to switch on a circuit ( with High Voltage) using an IR LED, or even a normal LED when its path is blocked ( low to no light ) to a sensor. And I quite honestly am not sure what type of sensor I should really look for. A photo-diode, or possibly a photo-transistor? It seems that the diodes that can handle upwards of 300vdc are far out of the price range for me, So i was thinking perhaps a photo-transistor would work better, although most of these things are trigger on light, instead of triggering on no light ( IR light is block, or maybe even use a small laser and laser sensor? ). The ability of the circuit to switch on extremely fast is important, and I need it to be built in a certain fashion that allows the use of the HV circuit becoming complete. Basically, the light path will be blocked, and in short order I need a HV circuit to activate in response. Voltages up to around 1kv will be used in the activated circuit, the path 'trip switch' does not need to be powered on the same circuit if that makes things easier.

author: IanB
author_rank: Super Contributor
timestamp: July 11, 2013, 04:29:17 am
content: Quote from: TheKraken on July 11, 2013, 04:07:44 amThe photo sensing element does not also have to be the switching element. Your design job will be much easier if you consider your circuit to be composed of two logical elements: a light detection element and a switching element. If you design this way you isolate one or the other to make testing easier. Furthermore you could swap out one switching element for another or one sensing element for another to get more options.Quote from: TheKraken on July 11, 2013, 04:07:44 amOf course. Transistors are switched on by current or voltage at the base and incident light energy does the same job. But there is nothing to stop you using another circuit element to invert the signal...

author: TheKraken
author_rank: Newbie
timestamp: July 11, 2013, 04:48:33 am
content: I was thinking about potentially using a 'Photo interupter' I had not found one previously for the sensing distance needed. I have a little 5mm slot type 'opto coupler' but need something more along the lines of 15-20mm for the application. I did find a few recently on digikey, There seem to be two types, logic output and transistor type, and im not quite sure which would be the best option. budget minded and simplicity of the switching function would be key.

author: IanB
author_rank: Super Contributor
timestamp: July 11, 2013, 04:59:07 am
content: IR remotes work from the other side of a room, so distance is not an intrinsic problem for a photodetector circuit.If there is ambient light in the surroundings you can modulate your source with a suitable frequency so you can filter out ambient light interference.To detect the object in the light path you can use a sensing circuit that looks for sudden changes in intensity of the receiving signal.
Photo resistor polarity - Page 1
Forum section: electronics / beginners

author: queennikki1972
author_rank: Regular Contributor
timestamp: May 09, 2019, 03:34:09 am
content: I built this circuit from a book, except it calls for a photo resistor. It claims that it will be louder as light increases, however when i built it, its the opposite. It is louder in the dark. Do photo resistors have some sort of polarity?

author: Jwillis
author_rank: Super Contributor
timestamp: May 09, 2019, 03:55:09 am
content: The resistance should go down when exposed to light .Check with a ohm meter to confirm.

author: floobydust
author_rank: Super Contributor
timestamp: May 09, 2019, 04:04:54 am
content: https://youtu.be/1NEIWixNTvIThe frequency changes (goes up with light) because the CdS cell's resistance is lower with light and thus charges the capacitor quicker.

author: AG6QR
author_rank: Frequent Contributor
timestamp: May 09, 2019, 05:41:05 am
content: Direct answer to your question: no, a CdS cell has no polarity.That circuit should change its frequency with light level, more light should be higher pitch. The amplitude shouldn't change much, but depending on the speaker you use, there could be significant volume changes due to the speaker's frequency response curve.

author: queennikki1972
author_rank: Regular Contributor
timestamp: May 09, 2019, 02:19:45 pm
content: The speaker I had was not identified as 8 ohms. I tried a different speaker and it worked properly.
Photocell allowing blips of power through - Page 1
Forum section: electronics / beginners

author: Phillipthegreat
author_rank: Newbie
timestamp: February 03, 2018, 05:30:18 am
content: Hello, allI've got a simple circuit I'm putting in a project wherein a hot ac-line photocell controls a usb powered strip of lights. It works great, in that it responds to light. However, when the room is bright/the photocell blocks power, every 5ish seconds, it lets power through for a fraction of a second and the lights blink on and then off. I need this to not happen because it's absolutely obnoxious. I figure that there's some small, cheap module out there that can make this stop, maybe by delaying the power from the cell by a second so that the cell has to allow power through for at least a second to actually power the lights on. Is this something common for photocells?Thanks a bunch for any help!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 03, 2018, 08:50:51 am
content: AC line? USB?If it's the light sensor letting leakage current through, try putting a DC load on it, like an incandescent nightlight, or a resistor.Tim

author: jeroen79
author_rank: Frequent Contributor
timestamp: February 03, 2018, 03:34:50 pm
content: Can you post what exactly you ave?Brand and type of the photocell and USB lightstrip?

author: Phillipthegreat
author_rank: Newbie
timestamp: February 09, 2018, 07:47:41 pm
content: Parts: the resistor is a philmore 'photo-electric switch', 25W max load, 125ac. The lights are this:https://www.amazon.com/gp/product/B01LY0M4D3/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1. The converter is a cheap "xtreme" 2.1 amp wall adapter.I ordered an on-delay timer module that I figure will fix this, but its gonna be a while in shipping.It already has a DC load on it with the lights, doesn't it? Or do I need a stronger load on it? I could also put it on a multimeter to see how much power it's letting through.

author: grifftech
author_rank: Frequent Contributor
timestamp: February 09, 2018, 07:59:49 pm
content: does it click when it turns on/off?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 09, 2018, 08:00:19 pm
content: Yeah, try putting, like, an incandescent night light in parallel with the power supply AC input.Tim

author: jmelson
author_rank: Super Contributor
timestamp: February 09, 2018, 08:03:00 pm
content: The photocell is not allowing "blips" of power through. It is allowing a steady stream of minute power to flow across, most likely due to capacitive coupling. This slowly builds up charge in a capacitor in the LED light power supply, and when enough charge has accumulated, the LED regulator switches on for a moment and then the charge is gone. Then, the cycle repeats.A small load on the AC mains input to the wall adapter will stop this. Loading the output of the wall adapter might not, as the wall adapter may be the thing accumulating charge and then pulsing on.Jon

author: SL4P
author_rank: Super Contributor
timestamp: February 10, 2018, 06:23:34 pm
content: p.s. Don’t let the photocell ‘see’ any light from the LED strip, or it may become a low frequency oscillator!
Photocell - Page 1
Forum section: electronics / beginners

author: DannnyG
author_rank: Newbie
timestamp: May 30, 2024, 01:42:01 pm
content: I got a 30 foot flagpole with 16' of led lights that will light up perfectly when I attach then to the fully charged 12 v battery. I bought a 10-50v photocell and tested it on my power supply using a small led strip and short wire. When I get out to the flag pole everything is connected properly and the photo cell clicks but doesn't work. The only difference I can see is the 30' of wire and using the power supply instead of the battery at the pole. I suspect the cheap photo cell but even if it is that please tell enlighten me on what the problem might be. I'm attaching the specs on the cell.

author: Terry Bites
author_rank: Super Contributor
timestamp: May 30, 2024, 02:50:16 pm
content: The word Tungsten is the clue.Its not designed to work with LEDS but old school tungsten lamps.Try adding a small (same voltage) tungsten across the LEDS.

author: DannnyG
author_rank: Newbie
timestamp: May 30, 2024, 03:03:36 pm
content: Newbie here Terry. I get the fact that the cell isn't for leds but don't know how to add a small tungsten across leds means?

author: jzx
author_rank: Regular Contributor
timestamp: May 30, 2024, 05:14:27 pm
content: You can connect in parallel with the leds. But I think that the label means "10A if you use tungsten lamps - 4.2A if you use E (lectronic?) ballast (fluorescent tubes?)". The first comma is a bit strange.If you can hear a click, the output switch must be a relay, that have no many problem with the type of load. A too long wire will give you more resistance and a dimmer light, but no an absolute fail.Are you sure that you have correctly connected the polarity of leds?

author: Terry Bites
author_rank: Super Contributor
timestamp: May 30, 2024, 06:06:46 pm
content: I mean put a filament bulb in parallel with the 12V leds. An old school tail light bulb or similar.All common filament bulbs are tungsten.

author: kevin.gibbs
author_rank: Regular Contributor
timestamp: August 23, 2024, 12:04:36 pm
content: If it clicks, it should work. You most likely need to connect it correctly. According to the diagram, “-” should always come from the lights, and “+” should come from the photo relay on the white wire. Check the polarity.
Photocoupler specs... CTR Truly important? - Page 1
Forum section: electronics / beginners

author: EEVPiobee
author_rank: Contributor
timestamp: March 28, 2014, 11:19:47 pm
content: Hello there... I'm wondering...I have an LTV817BNopto-coupler that seem to be dead on a circuit board and I'd like to replace it. Now I don't have it on hands, but it happens that I could salvage a 817Cfrom some "New old stock" device that was never used at all but already obsolete...Now, I've looked at the datasheet:http://pdf1.alldatasheet.com/datasheet-pdf/view/86744/LITEON/LTV817.htmlAnd the MAIN difference from the two is just that:817B : CTR 130-260 %817C : CTR 200-400 %Could one replace the other?Note: BN is on a TV's inverter power supply, as C is in a general standard power supply

author: ConKbot
author_rank: Super Contributor
timestamp: March 29, 2014, 12:01:24 am
content: I would expect an increase in CTR to not affect it too much as its probably just providing a digital signal for the feedback loop.If you were going the other way, a reduced CTR could possibly affect it if the design was marginal. In fact, as the LED degrades, you can lose output current, causing the same problems with aging. What sort of failure do you have that makes you think the opto-coupler? I'm guessing its not blown up and cratered since you say "seems to be dead" So LED aging is a possible failure mode. Have you done any testing on the opto?

author: EEVPiobee
author_rank: Contributor
timestamp: March 29, 2014, 05:18:05 pm
content: Well right until now I don't have any "advanced" way to test it, but, all the 817 optos I've tested on this board act like a diode on both sides with a multimeter and I get decent readings on both sides. (just as if I was reading a normal standard diode)But still, this 817BN one isn't blown up (destroyed cosmetically), but has an open side, no matter how I read it (polarity)..When I plug mains power on power board it's on, and send +5v signal for this supply (tv's inverter supply) to turn on, I just get nothing from, or even to the transformer...I can't really find another faulty part than this little one, and the logic board (that sends +5v) is actually a Samsung factory rebuild to specs...(Pic included is not the one I have in hands, but the exact same model taken from one eBay's auction..)

author: Zero999
author_rank: Super Contributor
timestamp: March 29, 2014, 07:41:18 pm
content: You're replacing it with an opto-isolator with a higher CTR so it should be fine.
Photodiode output emulation - Page 1
Forum section: electronics / beginners

author: elki
author_rank: Regular Contributor
timestamp: April 27, 2024, 04:26:47 pm
content: Does anyone know if there is a simple RC circuit that could emulate the current output of a photodiode? I wonder if it is possible to achieve starting from a function generator, pass it through an RC circuit, and then using the obtained current pulse as input to a transimpedance amplifier. Any suggestions are appreciated.

author: tggzzz
author_rank: Super Contributor
timestamp: April 27, 2024, 05:34:31 pm
content: Quote from: elki on April 27, 2024, 04:26:47 pmIn the late 70s I did just that: function generator->resistor->transimpedance amplifier. Worked just fine for my purposes, i.e. measuring the amplitude of a 1pW to 50µW optical signal.No idea whether or not it would work for your purposes depends on .... your purposes, oddly enough.

author: KrudyZ
author_rank: Frequent Contributor
timestamp: April 27, 2024, 05:41:08 pm
content: This depends very much on how accurate you want to model the PD behavior.The simplest would be to use a function generator and a resistor.This works if your PD is zero voltage biased and your circuit can work with either side of the PD being at Earth ground as that's where your function generator ground will usually be at.You are of course missing quite a few secondary effects of the PD, such as junction capacitance and non-linear behavior if voltage develops due to the TIA not maintaining the zero bias (during transients).The latter also affects the accuracy of the current. To minimize the effect, you should set the output voltage of the function generator as high as possible and then adjust for the desired current by picking larger resistor values (ideal current sources have infinite source resistance and infinite compliance voltage).That being said there are many PD configurations where what I described would not work, so we would need to see your schematics.

author: elki
author_rank: Regular Contributor
timestamp: April 27, 2024, 06:19:30 pm
content: Thanks a lot. I am using a photodiode that is voltage biased - cathode to positive power supply, anode to the input of the amplifier. If I understand correctly, the general approach would be just pass the pulse from function generator through a resistor to achieve the needed current.

author: tggzzz
author_rank: Super Contributor
timestamp: April 27, 2024, 06:49:07 pm
content: Quote from: KrudyZ on April 27, 2024, 05:41:08 pmIt works when simulating reverse-biassed PIN diodes, provided the input of the transimpedance amplifier is at (virtual) ground level.QuoteYup.The frequency and transient response fidelity are key requirements in the OP's use case.
photodiode with transimpedance amplifier  - Page 1
Forum section: electronics / beginners

author: mr_byte31
author_rank: Regular Contributor
timestamp: August 12, 2024, 01:22:01 pm
content: Hi Folks,I am reading more about transimpedance amplifier circuits. I am interested about a circuit with single supply.I found this circuit inTI application AN682I understand that the I_D current in the picture will be converted to voltage for R2.My understanding was to always connect the photodiode in reverse bias to make it sensitive to light and decrease capacitance.I wonder how this photodiode works. I can see terminals of the photodiode connected between ground and virtual ground. how that will make the photodiode work ?

author: Phil1977
author_rank: Frequent Contributor
timestamp: August 12, 2024, 01:33:37 pm
content: Each photodiode is also a solar cell - it just turns light into current.Applying some reverse bias can make the circuit more sensitive but also more complicated. But the shown circuit is a good starting point.

author: tggzzz
author_rank: Super Contributor
timestamp: August 12, 2024, 01:40:11 pm
content: Quote from: mr_byte31 on August 12, 2024, 01:22:01 pmNo, no, and yes, respectively.Search terms: photovoltaic mode, photoconductive mode.

author: Phil1977
author_rank: Frequent Contributor
timestamp: August 12, 2024, 02:21:33 pm
content: Here is a quite good overview about usage of photodiodes:https://www.teamwavelength.com/photodiode-basics/

author: TimFox
author_rank: Super Contributor
timestamp: August 12, 2024, 04:04:19 pm
content: Photovoltaic mode (zero bias, as drawn): higher capacitance, no dark current, medium shunt resistance (temperature dependent).Photoconductive mode (reverse bias): lower capacitance, appreciable dark current, high shunt resistance.In circuit, there are noise contributions from the dark current and the shunt resistance. The capacitance increases the noise gain at high frequencies, affecting the noise contribution from the op amp.Similarly, the offset drift results from the dark current and the DC noise gain determined by the resistances of the diode and feedback resistor operating on the offset drift of the op amp.Note that the slope of the I-V curve around zero volts bias is a finite resistance.
photoflash cap charger - Page 1
Forum section: electronics / beginners

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: March 19, 2019, 06:06:31 am
content: looking for resilient, robust, high speed(charge under ~3seconds) electrolytic photoflash cap charging circuit 350-400v 300uF-800uF.preferably something which triggers a switch device after cap reaches a preset voltage.anybody seen any?

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: March 19, 2019, 08:48:56 am
content: Quote from: blueskull on March 19, 2019, 06:46:32 amI was looking for small dc step up to cap voltage as in lipo powered.The voltage multiplier is least components to implement Im just not sure which form of capacitors are well suited for mains capacitve coupling.

author: soldar
author_rank: Super Contributor
timestamp: March 19, 2019, 09:15:34 am
content: Quote from: blueskull on March 19, 2019, 06:46:32 amIn Spain (at 230 V mains) no doubler needed. Many years ago I had a long, thin extension cord to my flash and was taking some photos in my apartment and went out to the terrace which had plain aluminum doors. My girlfriend (who was naked and the object of the session), as she stepped out did not realize the cable was there and closed one side and the door pinched the cord and sparks flew and the breaker tripped and she was startled and luckily she did not get an electric shock which she well could have. Some decades ago we were not so safety conscious. I remember a guy saying "protective earth is for sissies and a waste of money".Charging a flash capacitor from batteries requires a switching converter which would need to be of minimal volume and weight. My old flash just kept the oscillator going after it was charged and had a very simple system with a voltage divider and neon lamp to show when it was charged. The main problem is winding a tiny transformer but maybe you can find an old flash. I have a box full of old flash units which I have no idea why I am keeping them except that maybe one day I will play with them. The charging circuits inside are tiny and I doubt I could do it better.
Photomicrosensor slower than datasheet specs - Page 1
Forum section: electronics / beginners

author: GreyArea
author_rank: Contributor
timestamp: January 26, 2018, 08:45:12 pm
content: I'm trying to set up a circuit using the EE-SX1042 photomicrosensor/optical encoder (https://www.mouser.com/ds/2/307/sx1025-1190149.pdf).Working through the datasheet I came up with the circuit attached. The problem I have is that the fall time seems particularly slow (~500us) when compared to the datasheet (4us).After noticing that the RLvalue of the Condition/Combination table at the bottom of page 2 was 100R, I replaced R2 with that value. Now the high (0) signal is only 235mV and isn't usable logic levels.So, what's wrong with my circuit?

author: Kleinstein
author_rank: Super Contributor
timestamp: January 26, 2018, 08:50:41 pm
content: The load resistor at the detector side is likely much larger than in the DS. They usually specify the speed the a low resistance (e.g. 50 Ohms). The main part would be to avoid the transistor to go into saturation (e.g. voltage lower than about 0.2 V).

author: danadak
author_rank: Super Contributor
timestamp: January 26, 2018, 09:04:20 pm
content: This might help -https://www.vishay.com/docs/83590/fastswit.pdfRegards, Dana.

author: GreyArea
author_rank: Contributor
timestamp: January 27, 2018, 12:59:17 pm
content: What a fantastic document! Thanks all(puts the coffee machine on)

author: GreyArea
author_rank: Contributor
timestamp: January 27, 2018, 05:04:46 pm
content: OK, so after reading the application note (I must admit the analysis theory went largely over my head) my options seem to be:a) Reducing the emitters IF(dimmer IR LED).b) Tuning RLto reduce the saturation capacitance at the base of the phototransistor.I've now tried different values of RL, from 100K to 100R and it seems to make no difference to the turn off time at all, I've also reduled ILdown to 10mA (R1 = 380R in my circuit).According to the datasheet, 100R RLshould be down at ~3uS but by my reckoning, I'm like 3 orders of magnitude out with Vcc at 5V. If I was a 200-500us out, that would be fine for my application, but thousands of us just won't do.

author: BrianHG
author_rank: Super Contributor
timestamp: January 27, 2018, 05:35:37 pm
content: I'm curios, as a test, remove any obstruction from the encoder, then pulse the IR led with a square wave from a function generator & examine the speed of the waveform.

author: GreyArea
author_rank: Contributor
timestamp: January 28, 2018, 11:22:21 pm
content: Ah, that never occurred to me - I haven't even used my signal generator in anger - until now. It seems the issue was in fact mechanical, rather than electrical.Using a 10K R1 I can now trigger with about a 250uS fall time which is perfectly fine for my needs. Along the way I've learned about phototransistor base saturation and that if the detector doesn't poke into the gearbox as far as it needed to be, it won't work

author: BrianHG
author_rank: Super Contributor
timestamp: January 29, 2018, 02:34:19 am
content: Glad to be of inspirational help.
Photomultiplier amplifier circuit  - Page 1
Forum section: electronics / beginners

author: Alvin3424
author_rank: Newbie
timestamp: September 23, 2022, 02:38:47 pm
content: Hi I am new here, I don't know too much about circuits.I want to make that hand drew schematics but when I simulate it in Proteus it doesn't work(there is no signal or no positive wide signal). I don't know what I did wrong? maybe everything

author: jmelson
author_rank: Super Contributor
timestamp: September 23, 2022, 03:27:22 pm
content: Bat2 is applying 43 V directly to the input of the first op amp. the detector (when reverse-biased) isolates this from the input. You need to add in either a capacitor or reverse-biased diode to provide the same isolation for the simulator.Jon

author: Alvin3424
author_rank: Newbie
timestamp: September 23, 2022, 03:59:44 pm
content: I didn't understand, where I must add cap. I already added a diode. there is no 43 volt in Opamp input.

author: AlfBaz
author_rank: Super Contributor
timestamp: September 24, 2022, 12:00:01 am
content: I'd start by swapping the inverting and noninverting inputs on U2 and U3 firstYou have them backwards

author: Alvin3424
author_rank: Newbie
timestamp: September 24, 2022, 07:29:56 pm
content: Quote from: AlfBaz on September 24, 2022, 12:00:01 amit's new one but still not correct. I need wider signal on last channel.

author: Terry Bites
author_rank: Super Contributor
timestamp: October 07, 2022, 06:42:22 pm
content: Photodiode rather than PMT?Yes you're on the right track. Check your wiring.If you're looking for a fast pulse, AC couple the PD to the amplifier and between stages.Chucking it through a relay won't help. You want the first stage as close to the PD as you can.You've got the + and - inputs swapped on the 1st and second opamp. Your sketch is right, the CAD is wrong. C3 needs to be returned to the junction of R6 and R7. You need a cap, say 10u across R7You've got a CMOS amp so R6 and R7 do not be as low as 1k.The 43V battery does not need connect to this point. Just tie it to ground. The extra 2.5V isn't going so alter current by much.See typical set up attached. They've used pulse shaping. If you dont want that, increase the coupling cap between the stages.Question. why put the PD in a fast non linear mode and then slug the response in the input amp and lowpass filter?If you want a slow repsonse, put a resistor in series wit h the PD to ground and a simple noniniverting gain stage.https://www.rfwireless-world.com/Terminology/Difference-between-Photovoltaic-mode-and-Photoconductive-mode.htmlAlso attched, a curcuit that can null out the ambient flux and amplify the pulse flux. An inrtegrator controls Q1 which subtracts the ambient current from the amplifier. Effectively this amplifier is now AC coupled.

author: BeBuLamar
author_rank: Super Contributor
timestamp: October 07, 2022, 07:23:34 pm
content: I don't know what kind of photomuliplier you use but the one I know need about 1000VDC. They are very sensitive.
Photomultipliers that share a common node - Page 1
Forum section: electronics / beginners

author: LoveLaika
author_rank: Frequent Contributor
timestamp: November 06, 2020, 04:36:51 pm
content: I have a general question about SiPMs that share a common node. For reference, here's a datasheet of one such array.https://www.onsemi.com/pub/Collateral/ARRAYJ-SERIES-D.PDFLooking at figure 1 to keep it simple, they share a common connection at the cathode. I just wanted to ask: what issues do you think would occur as a result of sharing the common point without any other circuit elements to isolate them from each other? If three SiPMs fire, won't the corresponding signals affect the fourth one? Practically speaking, this may seem good if you want one large SiPM that fires all at once, but individually, this sort of design seems to pose a problem.

author: David Hess
author_rank: Super Contributor
timestamp: November 06, 2020, 06:18:56 pm
content: Sharing cathodes, or anodes, should have an insignificant effect. The current outputs reject variation of the bias voltage and the currents are low anyway.I suspect capacitive coupling between outputs will have a greater effect but this is minimized by driving a low impedance input like a transimpedance amplifier.

author: LoveLaika
author_rank: Frequent Contributor
timestamp: November 06, 2020, 07:05:46 pm
content: Using an amplifier aside, common readout methods include passing the current signal through a sense resistor and reading the voltage across that resistor. You can see it in Figure 6 in the doc below.Would the sharing of a common cathode/anode necessitate the need of a decoupling capacitor, in order to counteract the capacitive coupling? Following Fig 9 and 10, that should be no problem than to just increase the capacitance.https://sensl.com/downloads/ds/TN-Biasing_and_Readout.pdf
Photoresistor with HC-SR501 PIR - Page 1
Forum section: electronics / beginners

author: Sivand12
author_rank: Contributor
timestamp: November 20, 2014, 11:04:37 am
content: The instructions for this aren't great, but I gather that there are 2 empty slots for you to put a photoresistor on the board. Does anyone know how to adjust light sensitivity and other settings for this? I have not seen anything helpful in searches or the documentation.I am trying to create a motion-sensor night light without having to put a microcontroller in it.

author: elescondite
author_rank: Newbie
timestamp: December 23, 2014, 07:43:32 am
content: Digging around I came across a couple of answers... at least for the version I have:http://img.alibaba.com/img/pb/061/452/919/919452061_739.jpgThe schematic at the bottom ofhttp://www.wayengineer.com/human-infrared-sensor-module-hcsr501-p-896.htmlshows the LDR connected to pin 9 on the BISS0001 chip. The specs on that chip athttp://www.seeedstudio.com/wiki/images/2/2f/Twig_-_BISS0001.pdfshows that pin 9 will enable/disable the sensor at 0.2V. In other words, only operate in the dark. So it looks like it would work for you as is. Easy enough to find out.As for the other connection, I have seen photos marked as "thermistor". On my board the LDR holes are marked RL (resistor light?) and these ones as RT (resistor temp?).It's very hard to see the traces, but it almost appears to connect with the sensitivity potentiometer, which would (purely guessing here), adjust the sensitivity based on the ambient temperature. Makes some sense to my untrained mind!
Photoresistor with HC-SR501 PIR - Page 1
Forum section: electronics / beginners

author: ceamiclover
author_rank: Contributor
timestamp: October 15, 2014, 02:00:55 pm
content: The instructions for this aren't great, but I gather that there are 2 empty slots for you to put a photoresistor on the board. Does anyone know how to adjust light sensitivity and other settings for this? I have not seen anything helpful in searches or the documentation.I am trying to create a motion-sensor night light without having to put a microcontroller in it.
PHY remote testing - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: April 18, 2024, 06:08:23 am
content: When setting KSZ9131RNX to Remote Loopback, in addition to the register settings, there is a description that says "Connect RX_CLK to TX_CLK".Q1.Does this mean physically connecting Pin to Pin?Q2.If the above is correct, there are no pins named RX_CLK and TX_CLK, but does RX_CLK mean RXC (35 pin) and TX_CLK mean TXC (24 pin)?Screenshot 2024-04-18 111540[KSZ9131 Datasheet, Page#37, Section 4.13.2 REMOTE (FAR-END) LOOPBACK]Link:https://ww1.microchip.com/downloads...UNG/ProductDocuments/DataSheets/00002841D.pdf

author: m k
author_rank: Super Contributor
timestamp: April 21, 2024, 02:30:53 pm
content: Search "_CLK" and some say yes and some say no.It's like mixed software and hardware thing.

author: aliarifat794
author_rank: Regular Contributor
timestamp: April 21, 2024, 05:50:20 pm
content: Q1.It means physically connecting the RX_CLK pin to the TX_CLK pin.Q2. RX_CLK and TX_CLK are not directly labelled as such on the datasheet pinout. However, RX_CLK typically refers to the Receive Clock and TX_CLK refers to the Transmit Clock.

author: Vovk_Z
author_rank: Super Contributor
timestamp: April 22, 2024, 04:21:54 am
content: It seems thoese are TXC and RXC pins.
Physical mounting of a 0.96 oled display - Page 1
Forum section: electronics / beginners

author: Hixfield
author_rank: Contributor
timestamp: April 10, 2016, 08:57:08 pm
content: I have this popular 0.96 inch oled display that I want to mount in a case.http://www.ebay.com/itm/0-96-I2C-IIC-SPI-Serial-128X64-White-OLED-LCD-LED-Display-Module-for-Arduino-/201428440360?hash=item2ee6121528:g:MOYAAOSwv0tVeD0NI tried to dremel a nice rectange but the display itself is not rectangle in nature (ribben connector in the way) and pins are also sticking out. How does this normally get mounted in a case so that the outside is nice and flat? Sort of transparant film or something?

author: Blaffetuur
author_rank: Regular Contributor
timestamp: April 11, 2016, 07:07:08 am
content: What I've done is roughly cut out the hole for the display, hot glue the display in place and stick on a transparent film with a black border printed on it.

author: Bryan
author_rank: Frequent Contributor
timestamp: April 12, 2016, 06:18:32 am
content: How do you adhere the transparent film to the faceplate, some type of glue?

author: Blaffetuur
author_rank: Regular Contributor
timestamp: April 12, 2016, 06:26:00 am
content: Quote from: Bryan on April 12, 2016, 06:18:32 amThe film i print on is sticky on one side

author: PeterZ
author_rank: Regular Contributor
timestamp: April 12, 2016, 07:48:12 am
content: Here's how i'm going to do the LCD bezel for my next project: didn't have any transparent foil for laser printer at hand, so i just laminated one empty pouch, printed the frame on it and then laminated it again two times to make it thicker. Going to try that adhesive sticky tape used for cellphone display repairs to attach the LCD cover to the box.

author: customwidgets
author_rank: Newbie
timestamp: August 27, 2020, 12:36:14 pm
content: How about one of these?https://widget.gadgetsavvy.co.uk/bezel-for-128x64-oled-display/Disclaimer: I am the maker of these bezels.
Physical size of old Ceramic cap vs new ones ? - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: April 12, 2018, 05:02:16 am
content: I replaced an electro.cap backwards by accident, and when it blew up, it cracked a bit off an old 1960s ceramic cap.The cap is about the size of a quarter (a coin), 100n 25V, it's across a 9V zener, part of a -12V series pass regulator, in a Tektronix 422It should not get hot for any real reason, so can I just put in a little generic 100n ?

author: james_s
author_rank: Super Contributor
timestamp: April 12, 2018, 05:13:18 am
content: Generally that should be fine, parts have gotten much smaller over the years, not just caps. Do keep in mind that some types of ceramic capacitors lose a lot of capacitance when a DC voltage is present across them but that may not be an issue here.

author: Berni
author_rank: Super Contributor
timestamp: April 12, 2018, 05:56:49 am
content: Yep ceramic capacitor technology has come a long way.Tho for very compact capacitors like having 10uF in 0603 size there can be some not so nice effects setting in. Such capacitors use more exotic ceramic materials that have crappy characteristics. One of those 10uF caps turns into only 5uF when the rated voltage is applied and they are highly piezoelectric. If you apply a few volts AC at a few KHz across it it can start beeping loud enough to be heard into the next room. Same goes in reverse, if you smack the PCB it can generate a lot of voltage across itself from the vibration.But at capacitance as low as 100nF im sure anything is going to be fine as long as its not some tiny grain of salt sized capacitor.
Physics/Mechanics, converting torque to rpm - Page 1
Forum section: electronics / beginners

author: nForce
author_rank: Frequent Contributor
timestamp: July 26, 2019, 08:18:49 pm
content: I would like to know what is "mechanical dynamic equation" in mechanics and engineering to convert from torque to rpm? I know the relation T = J*alpha. But how to include motor characteristics for example slip (induction motor), friction, number of poles, mutual inductance?Thanks.

author: ArthurDent
author_rank: Super Contributor
timestamp: July 26, 2019, 09:38:53 pm
content: Here is an explanation of the relationship between torque/RPM but your question appears to be multi-part, too general, and not easy to solve in a brief time.http://www.epi-eng.com/piston_engine_technology/power_and_torque.htm

author: IanB
author_rank: Super Contributor
timestamp: July 26, 2019, 09:54:46 pm
content: Quote from: nForce on July 26, 2019, 08:18:49 pmIn the physics of linear motion you have:(power) = (force) x (speed)There is a direct equivalent for rotational motion:(power) = (torque) x (rotational speed)In each case you have to use consistent units of measure. So for linear motion you may have:power  = force  x speed [m/s]For rotational motion:power  = torque [N m] x rotational speed [rad/s]These are the mechanical equations.For electrical equations you will need to consult an electrical engineering text.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: July 26, 2019, 09:57:10 pm
content: Quote from: IanB on July 26, 2019, 09:54:46 pmon the money
Pi Attenuator Help - Page 1
Forum section: electronics / beginners

author: KSP
author_rank: Regular Contributor
timestamp: March 25, 2014, 11:36:10 am
content: Hi can someone point me in the right direction here please. I need to derive a formula to calculate the attenuation value of the attached attenuator. I have so far calculated the characteristic impedance Z0 to be 99.052ohm (correct me if I am wrong), so how do I calculate attenuation in dB using only the resistance. Usually I would do 20log(Vin/Vout) but how do I do it using just the resistances? Is there a way?Cheers

author: robrenz
author_rank: Super Contributor
timestamp: March 25, 2014, 11:42:05 am
content: http://chemandy.com/calculators/matching-pi-attenuator-calculator.htmformulas are below the calculator

author: KSP
author_rank: Regular Contributor
timestamp: March 25, 2014, 11:54:30 am
content: but that formula states:Att = SQRT(Zin/Zout) + SQRT((Zin/Zout)-1)which doesnt work because if the impedances are matched then this essentially tells me SQRT(1) + SQRT(0) which is nonsenseAm I missing something?

author: robrenz
author_rank: Super Contributor
timestamp: March 25, 2014, 12:27:29 pm
content: I read that formula is for theminimumattenuation

author: KSP
author_rank: Regular Contributor
timestamp: March 25, 2014, 12:34:29 pm
content: Ok well it seems the formulae are designed for unmatched impedances (as it says 'for Zin > Zout')I bodged a few things together and I got an answer which resembled what the calculator told me so I am gonna go with thatI made that a lot harder than it should have been...
PI regulator - integral windup - Page 1
Forum section: electronics / beginners

author: nForce
author_rank: Frequent Contributor
timestamp: November 15, 2019, 04:44:44 pm
content: Hello, if I have a PI regulator, where do I measure saturation, before the block of limiter (upper and lower bound) or after? I am asking regarding the windup integrator. And why do we measure there?Thank you for the help.

author: nForce
author_rank: Frequent Contributor
timestamp: November 16, 2019, 09:40:49 am
content: Sorry, but is my question incomprehensible?

author: iMo
author_rank: Super Contributor
timestamp: November 16, 2019, 09:58:11 am
content: A picture is worth a thousand words..