hybridfree/eevblog-posts huggingface dataset:
connecting a bluetooth audio receiver - Page 1
Forum section: electronics / beginners

author: Adhith
author_rank: Frequent Contributor
timestamp: October 09, 2016, 06:25:53 pm
content: hello everyonei'm trying to connect a bluetooth audio receiver(actually a dvd audio receiver unit) to my speakers. but i'am confused with the pinouts on the board, could anyone help me out?? i have added a pic of the receiver

author: andtfoot
author_rank: Unknown
timestamp: October 09, 2016, 10:24:16 pm
content: The top connector are the Auxiliary connections; most likely inputs into the receiver.The bottom connector are the outputs.For both connectors, top to bottom:- Left- Common/Ground- RightThe Mute connection doesn't look like it has been supplied a pin.

author: Adhith
author_rank: Frequent Contributor
timestamp: October 10, 2016, 11:03:50 am
content: Quote from: andtfoot on October 09, 2016, 10:24:16 pmIt is a bluetooth receiver which also support usb & aux so every thing is already connected to input within the pcb right?? so what must be given in the input??
Connecting a CH340G to 2.8V - Page 1
Forum section: electronics / beginners

author: soFPG
author_rank: Frequent Contributor
timestamp: July 17, 2020, 04:36:19 pm
content: Hello,according to the CH340G datasheet, it is 2.8V capable (I need 2.8V due to other components on my PCB).While TX / RX should run on 2.8V, D+ and D- for USB of course have to be 5V - right?I don't understand how to connect the CH340G to do this, there is a "V3"-Pin and a "VCC"-Pin.My idea was connecting 2.8V to "V3" and 5V to "VCC" - anyone here who has experience with this?But the datasheet says "V3 connect to VCC". If V3 connects to VCC, both are at 2.8V - how is this supposed to work with D+ and D-?
Connecting a Flash memory in TSOP48 package - Page 1
Forum section: electronics / beginners

author: miker7940
author_rank: Contributor
timestamp: April 02, 2016, 01:35:06 am
content: Hi everyoneSo I am replacing a old AM29F032S flash memory, hopefully with a sst39lf200a chip.Aside from different memory sizes (I'm going with 2 mbit * 16 version) and different voltagesHow would I connect this up to the circuit? I'm looking at the schematics, the AM29F032S has less Dx pins and more Ax pins (such as D0 and A12)So, my question is: Do I need to connect all these pins?I'm thinking I am meant to just connect the ones I have and leave the rest disconnected, but would like someone to confirm.Thanks

author: newbrain
author_rank: Super Contributor
timestamp: April 02, 2016, 09:30:59 am
content: Quote from: miker7940 on April 02, 2016, 01:35:06 amIt's not easy to help without a schematic and some more information:You are replacing a 32Mb (4M x 8bit) memory with 2Mb (128K x 16bit) one, is the smaller size enough (1/32: 128KB vs. 4MB)?How are you going to program the flash: in circuit or off line?The programming protocol are similar, but FW written for the older part will most probably not be compatible (e.g. the new part requires 0x5555/0x2AAA addresses, the old one 0x555/0x2AA, sector sizes are different etc.).Without the schematic, it's impossible to say if Vid (~12V) was used on the old part (doubtful), that will immediately fry the new one.Are you going to use level translators? Or move the whole design to 3.3V?That said, if the size is enough, I would use 10K pull-ups on the extra data lines: if the MSByte is not programmed they would not increase power consumption, and if the flash is programmed in-circuit they'll provide a steady 0xFF value to the MSByte.The address lines you're missing...well, they are missing.
Connecting a Motion Sensor to a Shelly Smart Relay - Page 1
Forum section: electronics / beginners

author: martinjuhasz
author_rank: Newbie
timestamp: August 09, 2020, 12:54:39 pm
content: Hey all,so i've got a Shelly Smart Relay and a PIR Motion Sensor, both for mains voltage hooked up.I'm having trouble switching the Shellys input when the Motion Sensor is activated.Here is the Shelly Smart Relay and the Motion Sensor:I've connected L and N on both devices and hooked up L' form the Motion Sensor to the Shellys SW1 input.The problem now is that the shelly always reports the SW1 is active, no matter if there is motion or not.I'm measuring 50V between SW1 and N when no motion is active and 230V when there is.Measuring between L' and N when its not hooked up to the Shelly correctly reports 0V when no motion and 230V when there is.When i put a 200k Ohm resistor between L' and SW1 it works, inverted, but it works. SW1 is active when there is no motion and inactive when there is movement.The PIR sensor seems to be a Relay Switching one ( i hear it clicking and its advertised as one), even it only has one output, but i guess its just sending mains voltage to L' when active.Does anyone know what the problem here could be, if this can be resolved without a resistor and if not, if its save to put one of these small hobby type ceramic resitors in between? there is no load on the PIRs L' output, its just there to activate the SW1 input.Any help or questions are appreciated.
connecting between isa backplanes - Page 1
Forum section: electronics / beginners

author: medical-nerd
author_rank: Regular Contributor
timestamp: January 06, 2015, 12:13:05 am
content: HiyaI'm having a 'retro' computer midlife crisis.I have a couple of PICMG SBC's and backplanes for these which have a couple of AT/PCI expansion sockets.I want to connect between the AT connector on the host backplane and another on a passive backplane with 14 AT/ISA connectors.The SBC probably won't have enough drive for the extension cables and extra sockets so I'm prepared to put a prototype board in each with wirewrapped buffers to give enough drive for the extra cards, this 'shouldnt' be too critical as the boards should only be driven at 8Mhz - obviously I have a lot of reading of the ISA specs to do before designing this.Has anyone done this before at a hobbyist level who can point me to the appropriate docs to start with. with so many connections to buffer I don't want to get into some stupid timing issue that I won't be able to debug - I want to leave that for the cards I want to build!!CheersSteve
Connecting COM and mains earth SMPS 3D printer - Page 1
Forum section: electronics / beginners

author: mawood
author_rank: Newbie
timestamp: June 19, 2017, 06:57:00 pm
content: Hi, I am working on a pretty large scale 3D printer and I have a 24v switchmode supply, the typical kind from china and I would like to know if it is safe to connect the terminals labeled com to the mains ground and the chassis of my printer.I would like to do this so the chassis can be used as gnd and keep the metal chassis safe (electrically).I'll attach some pics of the power supply and printer frame for people who may be interested.

author: MosherIV
author_rank: Super Contributor
timestamp: June 19, 2017, 08:30:02 pm
content: QuoteHave you checked is the metal chasis of the PSU is grounded?It should be!A) for safety andB) to help with EMCYou need to also check if the 'Common' is isolated (with power off, check with DMM is there is continuity between GND to Common and Neutral to Common) SMPS usually are isolated.Whether you can ground the common (or 0V) is dependant on the SMPS type or topology - so you need to find out.

author: mawood
author_rank: Newbie
timestamp: June 19, 2017, 08:54:44 pm
content: The com has no continuity to mains earth, the PSU chassis is mains earthed. So I should be OK to connect the COM to the chassis and use it as the -VE connection?

author: MosherIV
author_rank: Super Contributor
timestamp: June 19, 2017, 09:54:19 pm
content: Quote

author: mawood
author_rank: Newbie
timestamp: June 19, 2017, 11:09:34 pm
content: Heres a photo of the inside of the PSU, can you take a look for me please?Terminals are, from bottom to top, L, N, E, COM, COM, COM, +V, +V, +V

author: MosherIV
author_rank: Super Contributor
timestamp: June 20, 2017, 06:56:04 am
content: Showing a photo is still pretty useless. Are there any instructions? Have you asked the seller?Try joining earth to Common with a small value (eg 250mA) fast blow fuse. If it is ok, the fuse will not blow. If it is not ok, it will blow and hopefully the small value will stop any damage.

author: jwm_
author_rank: Frequent Contributor
timestamp: June 20, 2017, 07:23:33 am
content: I have a similar setup and hooked ground to the chassis but did not connect it to negative. The reason is that will cause your USB and other ports (like uC programming ports) to be referenced to earth ground, which can be problematic.

author: Brumby
author_rank: Unknown
timestamp: June 21, 2017, 02:46:10 am
content: Quote from: jwm_ on June 20, 2017, 07:23:33 amThis is a very important point.Earthing is not just an issue for the PSU and your chassis - but foreverythingthat is connected to either.
Connecting Linear Regulators in Series?  - Page 1
Forum section: electronics / beginners

author: ninjastrike
author_rank: Contributor
timestamp: December 21, 2014, 03:46:27 am
content: Hi,I'm quite a newbie when it comes to electronics. I'm trying to build a tube preamp for my headphones.High voltage is required at the cathode(300VDC).Is it possible to connect 3 TL783 Voltage regulators in series to produce such an output ?Cheers,Ash

author: Maxlor
author_rank: Frequent Contributor
timestamp: December 21, 2014, 04:54:04 am
content: Yes, it's possible. But I think you misunderstand how they work: LDOs only ever reduce voltage, never increase it. To create larger DC voltages from a smaller source, you'll have to use other methods, like boost regulators or charge pumps.

author: David_AVD
author_rank: Super Contributor
timestamp: December 21, 2014, 05:05:04 am
content: Unless they are thinking of using one regulator output as the reference (common terminal) for the next higher voltage up?Does the 300V really need to be regulated? Is approx the right voltage and smoothed not good enough?
Connecting loads of wires? - Page 1
Forum section: electronics / beginners

author: sourcedog
author_rank: Newbie
timestamp: February 19, 2014, 10:09:55 pm
content: So yea, I'm a total newbWorking on my first ever real electronics project (a 16x40 led matrix display) due to some, let's say, non-existant planning (hey, how hard can it be, right?) I'm left with a problem consisting of 160 wires that want to be connected from the led board to the board housing the max chips. There's not really space for connectors on either board, so yea, welcome to wiring hellI don't really want to desolder and rearrange everything, so I'm hoping to find a usable way to connect all the wires of each 8x8 to the respective max chip via some easy to use connection. So I could do with some nice, easy to use ideasNext time I'll plan ahead instead of just jumping straight into it, heh. Learn from your mistakes

author: uwezi
author_rank: Unknown
timestamp: February 19, 2014, 10:22:05 pm
content: No space for connectors you say?Otherwise my experience and recommendation would be to go for IDC connectors and flat cables. Depending on the layout you could bundle e.g. the 16 cables of each 8x8 in a single 2x8 pinhead connector on either side and then use press-on connectors and a 16-wire flat ribbon cable in between.I use such an arrangement to connect the 3x 40 wires in a measurement setup between a terminal bar on one side and an Agilent 34970A Data Acquisition Unit.

author: Psi
author_rank: Super Contributor
timestamp: February 19, 2014, 10:27:10 pm
content: Coloured ribbon cable can make things easier

author: uwezi
author_rank: Unknown
timestamp: February 19, 2014, 10:48:51 pm
content: Quote from: Psi on February 19, 2014, 10:27:10 pmThat's exactly what I used in my setup - to be more precise: colored, rolled up ribbon cable - for a newbie it's a good way to learn the resistor color code at the same time
Connecting "microphone" to smartphone - Page 1
Forum section: electronics / beginners

author: petergriffin56
author_rank: Contributor
timestamp: June 22, 2021, 08:44:05 am
content: Hi everyone,I'm working on a side project with the one of the goals being to leverage the average smartphone's audio frontend, specifically to record a small AC signal. Looking at your typical electret microphone circuit below, I'm keeping things pretty much the same, but instead of the vibrating element is an antenna, a JFET is also still used after it.Is my assumption that the biasing resistor and DC blocking capacitor are both inside the phone correct ? The MIC connection on headphones is biased, so the resistor must be on the phone side right ? And adding a series cap would remove the bias, so it would only make sense that this part of the circuit is all inside the phone.But android specifications and other sources state that the output impedance of a microphone should be around 1Kohm to a few Kohm at most. From what I understand the output impedance of a common source JFET circuit is dictated by the biasing resistor, so doesn't the phone hardware itself dictate output impedance ? Why do they specifiy it then ?I suspect this last question is somewhat related to the previous one, can I adjust the gain of the JFET by adding an additional series resistor ? Is this resistor what they mean by the output impedance of the microphone ?How else would I be able to add gain to my JFET ? I'm not familiar with transistors, from what I understand gain is -Gm (transconductance) * R. But most JFETs I look at have Gm values in the milli-siemens or micro-siemens range, makes it difficult to add gain when the output impedance is so limited.Can anybody help a n00b understand some of this a little better ?
Connecting multiple bnc equipment - Page 1
Forum section: electronics / beginners

author: Crambone
author_rank: Frequent Contributor
timestamp: November 17, 2021, 02:55:00 am
content: Hello, I’m using a Bird rf sampler 1.8 - 35 MHz and want to hook to my Rigol Digital Scope, HP Spectrum Analyzer and HP Frequency Counter. The issue I’m having is when I hook 2 up via a t I’m getting interference on my scope?Is there a certain way I should be doing this?

author: xrunner
author_rank: Super Contributor
timestamp: November 17, 2021, 03:04:22 am
content: Use one instrument at a time for the information you are interested in. If you want an accurate frequency measurement use the frequency counter with one cable. Same goes for the other two instruments. You do not need to monitor with all three at the same time. Why do you want to do that if I might ask?

author: bdunham7
author_rank: Super Contributor
timestamp: November 17, 2021, 03:43:35 am
content: Quote from: Crambone on November 17, 2021, 02:55:00 amAt that bandwidth you should be able to use an F-M-F tee at the oscilloscope and then run the input into one side and then the other side of the tee to the spectrum analyzer, with the center of the tee to the scope of course. If the SA is 50 ohms and the scope is 1M, you shouldn't have any significant reflection issues. As for adding the frequency counter, is it 1M input impedance?

author: fourfathom
author_rank: Super Contributor
timestamp: November 17, 2021, 03:44:22 am
content: Do you see any signal on your scope when you connect the scope to the counter and analyzer, with no sampler connected? If not, then you might be seeing a reflection caused by unterminated cables. If you are putting the tees in a chain, connect the analyzer (50 Ohm input impedance) as the last thing in the chain, and the presumably high-impedance input scope and counter in the middle of the chain.Failing that, perhaps use a three-way splitter and use 50 Ohm terminations on the scope and counter connections.If your analyzer and/or counter are actually generating this interference, then you might be able to use a directional splitter (see "hybrid coupler").
Connecting multiple PIN photodiodes to one amplifier - Page 1
Forum section: electronics / beginners

author: ealex
author_rank: Frequent Contributor
timestamp: August 09, 2017, 11:07:25 am
content: HelloWhile preparing for another project i found some info about "Photodiode Gamma Ray Detector":https://www.maximintegrated.com/en/app-notes/index.mvp/id/2236orhttp://www.vk2zay.net/article/265One photodiode is quite small -> chances of detecting something are small.Looking at the maxim data note ( as i'll have to build something similar any way ) - can i connect multiple PIN diodes in parallel so i get a bigger detection area ?

author: danadak
author_rank: Super Contributor
timestamp: August 09, 2017, 11:26:59 am
content: Yes, but circuit behavior changes due to increased C. See the comments inthe ap note links you provided. You could consider using sampling approachto problem looking at one diode at a time thru a mux. That would take carefuldesign as it intrinsically adds noise into the problem. Sampling on the orderof > 1 x N MSPS could be a starting point.Or use a discrete buffer for each diode, maybe a SS JFET buffer might bean approach.Regards, Dana.

author: ealex
author_rank: Frequent Contributor
timestamp: August 09, 2017, 11:46:21 am
content: thanks Danai think i'll go for the first approach: connect several in parallel and update components value.it will be just a quick and dirty experiment, as i already have the requested parts available

author: Kleinstein
author_rank: Super Contributor
timestamp: August 09, 2017, 03:11:12 pm
content: A larger diode capacitance would reduce the resolution possible for the energy, as it would increase the noise. A better amplifier could help here a little. So for best sensitivity in energy one would have separate amplifiers and peak detection for each diode. If the diodes are small it might be ok to parallel a few.Having only separate amplifiers but still combine the signals to the ADC is only a partial solution.
Connecting multiple step down converters together in parallel - Page 1
Forum section: electronics / beginners

author: woody363
author_rank: Newbie
timestamp: February 01, 2016, 01:12:14 pm
content: Hello,I'm trying to connect two SDC boards in parallel so that they can handle more current. I'm fairly sure one acts as a master and there can be multiple slaves through use of the sync pins. The datasheet is available here:http://www.farnell.com/datasheets/1746752.pdfThere is also this datasheet:http://www.farnell.com/datasheets/73783.pdfwhich as far as I can tell is for the same device but with the descriptions of JP1 and JP2 reversed (which is rather worrying).I also don't understand how to reconcile the two sync outputs +'ve and -'ve but only one sync input.I have cut JP1 on one device (slave) as indicated by the first datasheet and connected the positive sync out from the master to the sync in for the slave, as this seemed the most sensible interpretation.The two devices are connected at common, Vin and Vout. I expected the slaves voltage to sync up to that of the masters, however the output voltage simply reads as the highest of the two. Current doesn't seem to be evenly distributed either. I'm therefore assuming that the sync hasn't happened.two options:1: There is a typing error in the first datasheet and I've cut the wrong jumper2: The sync pins are connected wrong, quite likely as this was just a guess.Anyone got experience with these boards?Cheers,Woody

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 01, 2016, 01:31:57 pm
content: The data sheet says that the current limit must be adjusted down to 20A if multiple units are used in parallel.
Connecting Oscilloscope to Cypress 5LP PSoC as to not blow anything up - Page 1
Forum section: electronics / beginners

author: pdavis0
author_rank: Newbie
timestamp: September 10, 2023, 04:01:53 pm
content: I have a CY8KIT-059 PSoC 5LP board. I soldered the header pins to it so I can mount it on a breadboard. What I'd like to do is to use an oscilloscope to measure ADC and GPIO outputs (as per a course I'm taking where they're using an NScope for this purpose; as I already had an oscilloscope I decided to use that.Based on my reading, care must be taken when connecting boards to the an oscilloscope. This board in particular is powered by the PC via USB (it is a desktop PC in this case). The oscilloscope itself is similarly powered by mains. When I probe the USB ground pin on the edge connector to the GND pins on the board, I get a reading of ~0 ohms. When I probe USB ground with any of the GPIO pins I get a higher resistance value (in megaohms, per the meter). So two questions: what does this mean? And how would I safely probe the GPIO and ADC pins on this board?

author: DavidAlfa
author_rank: Super Contributor
timestamp: September 10, 2023, 04:36:02 pm
content: The problem only happens when measuring a potential non isolated from mains, like a SMPS primary.Otherwise there should be no problem at all. PC and Scope will be earthed anyways, so sharing the same ground.Of course connecting the scope ground clip to anything no being ground (Like VDD) will make a short!

author: pdavis0
author_rank: Newbie
timestamp: September 11, 2023, 02:05:24 am
content: So if I understand correctly:Mount PSoC to breadboardPlace a wire on the row of the breadboard that corresponds to the GND on the PSoCAttach ground clip of the oscilloscope probe to that wireProbe away

author: DavidAlfa
author_rank: Super Contributor
timestamp: September 11, 2023, 01:15:27 pm
content: Basically, yeah.I repeat, the problem comes when measuring something non isolated from mains, not your case!Even if you shorted VDD with the probe, that's little current and would not damage anything, not like shorting 300V from rectified mainsJust proceed without fear!
Connecting pads in custom package to GND in eagle ? - Page 1
Forum section: electronics / beginners

author: Jaunedeau
author_rank: Regular Contributor
timestamp: January 24, 2015, 12:18:28 pm
content: Hi,I am trying to make a eagle device forthismicro usb b vertical connector.For the mounting pads, I basically :-Drawn a rectangle in dimension, with a 180 curve on two sides-Draw a 1.1mm wide wire on top, bottom, tstop and bstop-Put a via in the center of the hole to connect top and bottom wireThis almost works. The problem I have is that whan I put the component on a pvb with a ground plane, the wire on the bottom layer are isolated from the ground plan, even when they have the same signal name (GND) and eagle want me to connect them (wire in the Unconnected layer). If I route the wire, then the connection is ok, but I still have an isolation all around the pad (except where I manually added a wire for routing).Did I do my package the wrong way ? Is there a step I forgot ?Thanks you,John.

author: Steffen
author_rank: Regular Contributor
timestamp: January 24, 2015, 06:22:05 pm
content: In the device package, use a pad insted and according to your requirements turn off thermals if you want seamless connections to your groundplane. around the pad you can draw your oval shape in copper (top/bottom) and add another line in the milling layer to get your oval hole. All auxilliary layers like cream,stop etc. have to fit too. This quirk should work for exoticly shaped pads.
Connecting PCBs together - Page 1
Forum section: electronics / beginners

author: Jackster
author_rank: Frequent Contributor
timestamp: March 04, 2017, 07:44:51 am
content: Hi all.Bit of an odd one. I need advise on connecting PCBs together like in a "H" arrangement.I basically require 3 PCBs, 2 vertical and one horizontal.The horizontal would need to connect to the two vertical ones either side.What method is best for this?I am thinking I need some tolerance with this. Not a lot but some.ThanksJack,

author: Richard Crowley
author_rank: Super Contributor
timestamp: March 04, 2017, 07:58:00 am
content: Size?Number of pins?Permanent or pluggable?My first thought was something like....

author: Jackster
author_rank: Frequent Contributor
timestamp: March 04, 2017, 08:04:01 am
content: Quote from: Richard Crowley on March 04, 2017, 07:58:00 amBoards are all 25x50mm.Pins from 4 to 10.Permanent.Was thinking something along those lines.

author: Avacee
author_rank: Unknown
timestamp: March 04, 2017, 09:16:10 am
content: Not sure if this matches your requirements but Mike shows one solution in this video - go to 8:17

author: Rudane
author_rank: Regular Contributor
timestamp: March 04, 2017, 08:07:00 pm
content: Depends on the environment. If you are doing this at home for a hobby, what's suggested is fine. If you are moving to a design you plan to sell, consider that a solder joint is not meant for mechanical stability and using fasteners would be a better option.

author: Electro707
author_rank: Contributor
timestamp: March 04, 2017, 08:59:08 pm
content: If they are far apart where you can't connect them with pin header i recommend either ribbon cable or something along those lines.
Connecting Power Brick 0V to metal enclosure. - Page 1
Forum section: electronics / beginners

author: ecat
author_rank: Frequent Contributor
timestamp: April 28, 2014, 02:27:49 pm
content: Just a quick question on safety.As I understand it, the output from most switch mode power bricks is floating. Are there any safety concerns connecting the brick's 0V, or any other output line, to the metal case of a hand-held device?

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 28, 2014, 02:41:28 pm
content: ASSUMING you are talking about a proper power brick (or wall wart) that has inspection certification (CE, UL, et.al.), I would have confidence that the output (either positive or negative) is sufficiently isolated from the power mains that it is inherently safe.

author: ecat
author_rank: Frequent Contributor
timestamp: April 28, 2014, 03:24:28 pm
content: Thank you for the quick reply.My concern is two fold, the inherent isolation but also what happens if the user has the metal case in one hand and touches some other metal cased and earthed mains appliance?

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 28, 2014, 03:57:53 pm
content: That is exactly what I mean by "inherently safe". That is one of the things that all those inspection certifications test for.

author: ecat
author_rank: Frequent Contributor
timestamp: April 28, 2014, 07:35:07 pm
content: And that's all there is too it? Excellent, thanks again.I was remembering when a colleague had his battery powered laptop connected to some industrial cabinet by a rs232 cable, battery was running low, he connected the power brick and things went pop. Didn't want to risk popping people.

author: lewis
author_rank: Frequent Contributor
timestamp: April 28, 2014, 07:45:11 pm
content: You have to be a bit careful, on some power supplies you can measure ~150V between output and mains earth with a good digital multimeter, assuming the power supply is a class II type (not earthed - double insulated). The current is very low, but might be felt by some. The standards bodies set limits on 'Touch current'; BSEN 60990 shows some ways to measure it.

author: Zero999
author_rank: Super Contributor
timestamp: April 28, 2014, 08:02:17 pm
content: Quote from: ecat on April 28, 2014, 07:35:07 pmIt's possible the RS232 output isn't isolated and connecting it to the earthed industrial equipment caused a short circuit.Quote from: lewis on April 28, 2014, 07:45:11 pmYes, under certain conditions, it's possible to feel a tingle, especially if the current passes through a small area of the body with a high density of nerve endings, such as the fingers. This is only a problem if the appliance is used in a hospital, where there's a risk the current could pass straight through the heart, in which case this is easily remedied by connecting it to an isolation transformer.The main hazard to electrical equipment is ESD, that 150V is enough to destroy the gate of a MOSFET, although proper design can protect against this.
connecting pushbutton to IC - Page 1
Forum section: electronics / beginners

author: fisz
author_rank: Contributor
timestamp: October 21, 2016, 09:23:39 am
content: From what I understand, to connect a pushbutton to a microcontroller, it is enough to do it like this:http://playground.arduino.cc/CommonTopics/PullUpDownResistorWhen shorted, the pushbutton connects either Vin or ground directly to input pin, and when open it connects to ground via pulldown or to Vin via pullup resistor respectively.However, I came across this schematics:https://www.cooking-hacks.com/media/cooking/images/documentation/tutorial_ir/ir_remote_pushbuttons_small.png(source:https://www.cooking-hacks.com/documentation/tutorials/control-hvac-infrared-devices-from-the-internet-with-ir-remote/)Could someone explain the purpose of it (especially the R20 and R21 resistors)?

author: Ian.M
author_rank: Super Contributor
timestamp: October 21, 2016, 09:37:11 am
content: Its likely to be to reduce the 5V signal from the switch to 3.3V logic levels, though IMHO the 1K5 resistor should be increased to 1K8 (nearest preferred value to 1.7K). Also the 10K pulldown resistors are redundant if it is driving a 3.3V MCU. It will be problematic with most 5V MCUs (out of spec logic '1' level) unless they either have TTL compatible input thresholds, or the 3K3 resistors are removed and the 10K resistors are kept.The other thing it does is put 1.5K between any ESD at the switch and the MCU input pin, which will vastly increase its ESD tolerance, by limiting the peak current its internal protection diodes have to clamp.
Connecting RF function gen to AF generator - Page 1
Forum section: electronics / beginners

author: stevie3d
author_rank: Newbie
timestamp: March 25, 2017, 08:26:00 am
content: I've got a BK Precision 4040A 20 MHz Sweep Function Generator I'm trying to get a 3 to 4mhz square wave RF carrier with a 500hz through 130khz AF modulated piggybacked signal on it with a 1 to 2 sec.sweep. I have an Separate AF gen if needed. Can I just hook the outputs in parallel, or do I need matching circuits, transformer, caps, coils, resistors. I also have a function gen. amplifier 40db. and an Audio amplifier for the AF generator. I'm just trying to not smoke my $1000 worth of equipment I just bought new to a crisp. I dropped out of electronics as we were getting into RF, carriers, the stuff I need now. Thanks for any help or literature you could point me to. Steven Dixon

author: ebclr
author_rank: Super Contributor
timestamp: March 25, 2017, 09:00:17 am
content: "3 to 4mhz square wave RF carrier"Conceptual problem herea 4 Mhz square wave, will have a lot of heavy harmonics, Rf carrier must be sinusoidal if you don't want to use all the rf spectrum for yourself.If your rf generator does not have a input for modulation you will needa modulatorsomething like this

author: David Hess
author_rank: Super Contributor
timestamp: March 27, 2017, 12:42:26 am
content: Set the 4040A to external AM modulation and apply the modulation signal to the modulation input. Set the sweep limits and duration as required.
Connecting same voltage node  - Page 1
Forum section: electronics / beginners

author: Vcky_electro
author_rank: Contributor
timestamp: September 28, 2019, 11:25:29 am
content: Hi,Im designing the regulator adaptor board for the camera board. Where camera board requires 700mA@3.3V. Host board having 3.3V and 1.2V supply. But host can support 300mA@3.3V. So I thought to boost the 1.2V to 3.3V and connect both 3.3V to the camera board. will it introduce any problem??Thanks,Vicky
connecting Signal generator to oscilloscope - Page 1
Forum section: electronics / beginners

author: Charlietuna
author_rank: Newbie
timestamp: August 31, 2010, 06:08:04 am
content: I bought a used signal generator,freq output 1mhz to 520 mhz. I would like to see the signal on the scope. The rf output of the sg is female type n connector. Can I use a type n to bnc adapter and then a bnc cable directly into the scope? Should I use the scope probe and just probe the type n connector?TIA for your help.Steve

author: Simon
author_rank: Unknown
timestamp: August 31, 2010, 06:33:59 am
content: you can "probe" the socket or a cable with your probe or make a direct cable connection, up to you, the direct connection should eliminate the possibility of picking up other interference

author: jahonen
author_rank: Super Contributor
timestamp: August 31, 2010, 06:51:39 am
content: Yes, you can use adapters as you mentioned. Another way would be to use N-type cable and N-female to BNC adapter at scope end. Note that most RF equipment assumes terminated connections, so if your scope does not have internal 50 ohm termination option, then you should get 50 ohm BNC inline terminator, like this:That is better than T-branch and separate termination.Regards,Jane

author: Unknown
author_rank: Unknown
timestamp: August 31, 2010, 07:01:18 am
content: Make sure you connect the feed-through terminator directly to your scopes input, you want to keep the stub in parallel with the terminator as short as possible (which is why a feed-through terminator is better than a tee and regular terminator). Converting it to BNC and using a BNC cable (or N-to-BNC cable) and terminating it at your scopes end (either internal or external feed-through terminator) would be the best solution in my opinion.

author: Charlietuna
author_rank: Newbie
timestamp: September 02, 2010, 04:12:41 pm
content: Thank you all for your help.Where can you buy the terminator you showed in the picture?Thanks,Steve

author: jahonen
author_rank: Super Contributor
timestamp: September 02, 2010, 05:07:52 pm
content: You can find them atDigi-Keyfor example. That particular one is specified up to 500 MHz.Regards,Janne
Connecting smart lock over zigbee for IoT actions. - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: July 20, 2016, 05:38:10 pm
content: Now a days there are many smart locks available like kwikset, these locks have ability to connect through zigbee to offer more functionalities.I want to develop a project on this, I visited manufacturer's web site but did not find any helpful information, like connecting smart lock through MCU over zigbee, sending commands and receiving response from lock etc. need help where should I start from, is it possible that without manufacturer's documentation I can connect to a smart lock and set code on it, perform lock and un-lock actions.

author: Kilrah
author_rank: Unknown
timestamp: July 20, 2016, 05:46:46 pm
content: I'd guess it depends on your lock, if it's meant/marketed for custom user actions or not, if yes that would be documented.You'd expect that to either be tightly specified if intended, or tightly protected if that's not meant to be a feature.

author: sairfan1
author_rank: Frequent Contributor
timestamp: July 20, 2016, 08:19:00 pm
content: These locks are compatible with many security companies here in Canada like Vivint, Sasktel etc. we can simply pair /connect these locks with control box provided by security company, and then we can check state of lock, lock or unlock from remote location through application provided by security company. There are number of different brands of such smart locks that can be connected with control box.While visiting manufacturer's web site (http://www.kwikset.com/) I came to know that these lock have ability to pair with any zigbee based device to set the code and lock/unlock actions.
Connecting the output from a function generator through a BNC cable to the input - Page 1
Forum section: electronics / beginners

author: john1998
author_rank: Newbie
timestamp: June 25, 2018, 04:32:20 am
content: I am trying to work with the signals generated by a function generator using Raspberry Pi. Since Raspberry Pi does not have an inbuilt ADC, I used pcf8591. Now, I do not know how to feed the signal generated by the function generator into the input pins of pcf8591. Please help.

author: Zero999
author_rank: Super Contributor
timestamp: June 25, 2018, 10:10:24 am
content: What part are you struggling with?The input to the ADC needs to be biased at half the supply voltage and the signal generator must be loaded with 50Ohm, to avoid reflections.This circuit will bias the ADC at 2.5V and has an input impedance of exactly 50Ohm, at high frequencies.What's the lowest frequency of interest? This circuit has a cut-off frequency of just over 62Hz. If you need to go lower, increase the value of C1.
Connecting two "same voltage" power sources - Page 1
Forum section: electronics / beginners

author: namlu
author_rank: Contributor
timestamp: September 14, 2014, 08:47:11 pm
content: Hello.My circuit can operate with 2 power sources: 12v dc from external dc source or 220v ac that goes to 12v ac to dc module. Output of the ac dc module is connected to the 12v dc input.They are both 12 volts, but may be around 0.5 volt different from each other. If I connect both ac and dc at the same time, there would be 0.5v on non loaded wire.How should I connect 12v dc and 12v ac-dc so I can connect both sources at same time? Should I put some passive component between them?Thank you.Sent from my iPad using Tapatalk

author: Araho
author_rank: Regular Contributor
timestamp: September 14, 2014, 08:56:17 pm
content: Simplest would perhaps be to Diode-OR them? (Seehttp://en.wikipedia.org/wiki/Diode-or_circuit)That is, if you don't mind the voltage drop across the diode.

author: sparx
author_rank: Contributor
timestamp: September 14, 2014, 09:42:02 pm
content: Could you use a relay (Normally closed) between 12V DC input and the point the ac-dc converter connects, when mains is used, the relay opens d/c the 12v external input? No drop then?

author: Richard Crowley
author_rank: Super Contributor
timestamp: September 14, 2014, 10:02:36 pm
content: If we are to assume (since you did not explicitly state it) that you want both power sources available simultaneously (or automatically switch-over), most DC power input connectors feature a built-in switching contact that disables an internal source when the connector is engaged.There are transistor switching methods similar to sparx' suggestion for the relay scheme. Some Arduino boards featured this scheme where the board would automatically switch to the USB power source whenever available, etc.Not nearly enough information about your application to really give you suitable suggestions.

author: Jeroen3
author_rank: Super Contributor
timestamp: September 18, 2014, 09:56:19 am
content: Linear technology has some powerpath or ideal diode IC's. Such as the LTC4412.That might be helpful if you do not want to share load, or want more control over the active source.
Connecting two bucks in series - Page 1
Forum section: electronics / beginners

author: mdijkens
author_rank: Regular Contributor
timestamp: March 05, 2017, 04:31:45 pm
content: Hi I have two ofthese unitsAccording to the manufacturer they are not designed to put in series.I want to power them with two separate SPS from old HP laptops. These SPS seem isolated to me (very high (Megaohm) resistanceIf they are really isolated, could there still be a problem putting them in series?I want to use it to for example to easily create a positive and negative rail on my breadboard projects with only low current circuits ....I don't want to brick them!Can I do this? test it in a safe way?Are there precautions I need or can take?

author: jeroen79
author_rank: Frequent Contributor
timestamp: March 05, 2017, 06:20:36 pm
content: If the supplies to the buckmodules are isolated then the buckmodules will be isolated as well and you can put them in series.

author: mdijkens
author_rank: Regular Contributor
timestamp: March 05, 2017, 10:08:44 pm
content: ThanksAs a beginner, what is isolated? If I read 1M ohm between in and out of the SPS, does that count as isolated?

author: Gregg
author_rank: Super Contributor
timestamp: March 05, 2017, 11:26:48 pm
content: Quote from: mdijkens on March 05, 2017, 10:08:44 pmThe buck converters you listed are not isolated in the sense that the input terminals are not totally separated from the output terminals. You can check with your multimeter in both ohms and diode modes in every possible configuration. This means that you cannot series the buck converters from the same input source.However if both of your laptop power supplies are confirmed totally isolated form their inputs, you have a chance of making it work. Try powering both laptop power supplies and measuring voltage across the outputs between the two; you may get some phantom voltages that go away with a fairly high resistance (like 20K) connected to the terminals you are testing.After you have confirmed that the laptop power supplies are indeed isolated, try connecting your buck converters to them and before connecting them in series test voltages between outputs like you did for the laptop power supplies. You might want to put separate loads on them for testing.If all seems isolated, before connecting them in series, you probably should put some appropriate diodes on the output of each buck converter to prevent any reverse spikes or currents that will brick them. This will mean the voltage read on the buck converter meter will be less at the load because of the diode voltage drop but the internal meters will still be a reasonable reference for balancing the two converters.Think of all the ways things could go wrong and test / correct them before powering up anything.And remember that the current may like the best path but it will find any path and screw up your day.

author: mdijkens
author_rank: Regular Contributor
timestamp: March 06, 2017, 06:19:24 pm
content: Thanks Gregg for your tips.I'll do all tests step by step to see if it is really isolated
Connecting two i2c sensors to same level translator? - Page 1
Forum section: electronics / beginners

author: mangekyo
author_rank: Contributor
timestamp: November 19, 2022, 03:54:02 am
content: Hi,I am connecting two i2c sensors to a microcontroller running on 5V. The sensors are both 3.3V sensitive but have their own unique addresses.Can I connect both sensors to one single level translators SDA and SCL inputs like this:https://freeimage.host/i/H9b1ttfOr do they require two different level translators or do I maybe need to place pull up resistors for both sensors?The level translator I am using is LSF0102DCUhttps://www.ti.com/lit/ds/symlink/lsf0102.pdf?ts=1668761099920

author: ataradov
author_rank: Super Contributor
timestamp: November 19, 2022, 04:26:57 am
content: Yes, you can. The level shifter does just that - shifts levels. Otherwise everything works just as it would with a single voltage bus. So, if your MCU was 3.3 V and a combination of devices worked on the same bus (different addresses) when connected directly, then it would also work when connected though a level shifter.Also, that's a pretty cool level shifter. It is somehow cheaper than a couple of MOSFETs traditionally used for this, at least in low quantities. At higher quantities MOSFET prices drop faster.

author: pcprogrammer
author_rank: Super Contributor
timestamp: November 19, 2022, 06:21:04 am
content: It will work fine with just the one level shifter. But the pull up resistors in your schematic are to high and would normally have the same value. 2K2 Ohm is often used for I2C.

author: ataradov
author_rank: Super Contributor
timestamp: November 19, 2022, 06:24:21 am
content: 4.7k is a pretty common value for 100 kHz bus. But 10k is a bit much and you don't want them to be asymmetric too.
Connecting Ultrasound Transducer Output to Laptop - Page 1
Forum section: electronics / beginners

author: adam2392
author_rank: Newbie
timestamp: October 09, 2015, 05:20:16 pm
content: I am a beginner/intermediate electronics person. I have never bought electronics components before and only worked on Arduino/Raspberry Pi stuff. Hoping to get some guidance, so that I know what I am buying and why I am buying it and how to setup a hardware setup to get an analog signal.Background: My setup currently has 2 ultrasound transducers. I will pulse one of them and then collect output from the other. My problem has to do will collecting the output. Normally, one can do this via an oscilloscope, but I want to gather this data and store it/transfer it to my laptop, so that I can run digital signal processing on it.I am trying to get a signal that is coming out of an ultrasound transducer at ~1MHz +/- 5V. It is a sinusoidal analog signal that is generated from the ultrasound transducer. I suppose I would like a resolution of 10 bits (should be good enough for +/-5V). And for Nyquist sampling, I would want something sampling at probably 3MHz to capture the signal effectively.I am wondering what sort of ADC is out there that can do this. If so, where can I find this and how should I go about buying it. Would you be able to provide me with some links and specific examples? I go on google and search and I feel like I just get bombarded with different results I don't understand.

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: October 09, 2015, 10:42:06 pm
content: Digilent Analog Discovery board?http://www.eevblog.com/2014/12/13/eevblog-692-digilent-analog-discovery-review/http://www.wsj.com/articles/SB123869022704882969

author: ealex
author_rank: Frequent Contributor
timestamp: October 10, 2015, 10:40:54 am
content: how do you need to process the 1Mhz sinewave? you can use a ne602 mixer and downconvert the signal to something that an audio card can handle - like done in the cheap SDR receivers. i've seen this used in some 'bat detector' circuit somewhere.

author: adam2392
author_rank: Newbie
timestamp: October 12, 2015, 06:53:18 pm
content: The digilent seems too expensive. It is >200$. I was looking for a cheap way to get the signal and into the laptop. If I have to do some extra steps digitally that is fine.I am trying to process the 1 MHz signal spectrally. So this means conducting FFT on it to get frequency characteristics out of it.
Connection 0V together !(High Voltage) - Page 1
Forum section: electronics / beginners

author: QWERTYQWQ
author_rank: Contributor
timestamp: October 24, 2019, 01:36:45 pm
content: hi folks..First of all ,im a newbie(my first post) here and im sayin all of you guys HELLO!Nowadays im working on VFD . Since today the all project were going well so i could handle. But today(!) , i hit the wall .....The main goal is to controll FETs by DC Bus [ from a transformerless power supply (311Vdc) ] . Transformerless power supply works fine and doing well with it. The problem is connection of DC Bus's 0V to another power supply's 0V...As you guys know H-bridge of the configuration's Gate terminals must drive with low voltage (in my case 20Vmax Vgs). There is also a optoisolator (totem pole) at the output of the control circuitry. The opto's Vcc must 12Vdc(the 12v is comming from smps) for driving the FET's Gate terminal and also the 0V of the SMPS should connect to 311Vdc bus's 0V. But couldnt figure it out to connect to 0V pins together !!!!!I have tested with my oscilloscope and i have noticed 311V peak half rectified signal between each others(as expected before). The reason why im here to solve this situation with you guys comment. How can i generate or connect 12Vdc voltage to opto's Vcc pinIm going to be crazy right now. I tried to tell my problem as much as i can. If you guys have any advice to me , im happy to read your comments..Thanks A Lot.QWERTY.

author: Zero999
author_rank: Super Contributor
timestamp: October 25, 2019, 10:05:30 pm
content: I'm sure I saw a detailed reply to the same question yesterday. Either this is a repeat, from another account or there was an error and it got deleted.The 0V rails should all be connected to a single point. Beware that the DC bus and the output of the inverter, will be floating at the mains voltage, so you can't connect it to 0V. You need to use two channels of the oscilloscope working in differential mode to look at the output voltage.Also note the hazards when working with transformerless power supplies, which aren't isolated from the mains.