hybridfree/eevblog-posts huggingface dataset:
radiated emissions inside power supply effecting microcontroller? - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: September 27, 2014, 05:20:11 am
content: Can I put a MCU on the same board as a switchmode power supply? It is galvanically/optically isolated on its own ground plane. The MCU is 3 inches away from any mains connections, which is switching 5A@110V@10KHz. The gap between the two ground planes is ~0.3 inches.Should I put the option for a shield can around the mains SMPSU? There is no analog stuff that is exposed to anything, just a MCU/RS232 interface.Could a shield like this possibly be effective?*star washer under screw

author: Rerouter
author_rank: Super Contributor
timestamp: September 27, 2014, 06:47:13 am
content: there should only be 2 cases where a micro can be upset inside a noisy enviroment, the first is noise coupling through long or high impedance traces, the second is its supply rails / reset line, follow good decoupling practices on the supply rails, and add a pull up or pull down resistance on every pin that is not being driven hard, to ensure that both noise cant cause a glitch and secondly positive or negative going spikes have somewhere to go if coupled that strongly,

author: SArepairman
author_rank: Frequent Contributor
timestamp: September 27, 2014, 06:55:02 pm
content: If there is a long trace between two devices (such as a RS232 chip) should I distribute the pull down resistor between the two chips b/c of the trace inductance (5 inches )?Would the shield that I described get rid of a need for the extra pulldown?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 27, 2014, 11:21:30 pm
content: I don't see how there'll be enough noise to cause problems at pretty much any distance... it's just logic...Tim

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 27, 2014, 11:22:31 pm
content: Quote from: SArepairman on September 27, 2014, 06:55:02 pmPulldowns have very little effect on signal quality. You need resistors on the order of Z_0 to do that. Typical trace impedances are around 100 ohms.Tim

author: poorchava
author_rank: Super Contributor
timestamp: September 29, 2014, 07:36:39 pm
content: 10kHz seems way low for a mains psu. It's gonna emit audible noise. Why don't you move the frequency to somewhere around 30kHz?

author: SArepairman
author_rank: Frequent Contributor
timestamp: September 30, 2014, 02:41:40 am
content: Quote from: poorchava on September 29, 2014, 07:36:39 pmas the pic programs it I can put a time delay on it, so it fools the customer into thinking that it is quiet and then wham bam 5KHz switchingi wonder if its possible to play music with a switcher, or even speech...
radiated emissions testing intentional radiator test setup? - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: June 16, 2020, 10:33:20 pm
content: In the past when testing unintentional radiators for example something with an Ethernet port in an anechoic chamber for radiated emissions we had to exercise the Comm ports as they would be used normally. So we typically had a pc outside the chamber continuously talking to the DUT.For intentional radiators for example WiFi or Bluetooth, to communicate with the DUT as they normally will, requires the companion transceiver to be in the chamber or at least have an antenna inside the chamber. If that’s the case how does the test equipment and or operator distinguish between the DUT and the companion device during the scan?
Radio board going crazy with radio transmitter - Page 1
Forum section: electronics / projects

author: rvalente
author_rank: Frequent Contributor
timestamp: June 26, 2019, 11:49:44 pm
content: Hello Mates,this prototype has a very simple task, on the push of a buttom a recorded message is played through the HAM radio on a commercial frequency.Its a very crude notification system.(The seen band is HAM but, the end use will be commercial band).The radio is being powered by a battery eliminator, just a 7808 inside the baofeng battery case.The board is supplied with 12V from the lab power supply.When the button is pushed the STM32 (running arduino) sends a very simple serial burst to the MP3 player, which turns on the TX transitor to the radio and feeds the audio to the radio.The STM32 checks the end of the message by pulling the MP3 player "playing pin" and while is low, the TX is held down.The radio is driving everything crazy (5W tx power on VHF), the lab power supply galvo goes crazy, the board STM32 thinks the audio is still playing and I'm obliged to remove the headphone jack to quiet everything down.There is no ground plane at all since I'm using the perfboard with 0805 and enamel wire for connections and there is little to no noise suppression.My question is: What kind of noise suppression should I use? How to calculate it?

author: DimitriP
author_rank: Super Contributor
timestamp: June 27, 2019, 12:11:16 am
content: QuoteThere is no "noise".I almost went crazy by looking at itYou are describing RFI, picked up by the miles of interconnecting wires.The first answer is better layout.The second answer is instead of blasting 5W while testing use lower power.I was going to say add capacitors and RF chockes along signal paths inputs and outputs but with the current layout it's a crapshoot ....

author: thinkfat
author_rank: Unknown
timestamp: June 27, 2019, 06:44:13 pm
content: If you cannot reduce the TX power, connect the transceiver to a dummy load during testing.I hope this is not the final setup, you'll have a hard time getting all the radio interference under control. I suggest you put a lot more distance between the transceiver and your board and use a choke on the connecting wire to block the RF. Or use a separate antenna that you place a couple ten meters away from your board.

author: rvalente
author_rank: Frequent Contributor
timestamp: June 29, 2019, 07:52:06 pm
content: Hello friends,I much appreciate your replies.As suggested, did some things:Added a small filter in the input power supply, just a 47uh inductor and a 10uF cap.Added a small shield in the bottom of the board.The antenna is not anymore in the radio, but with a 1m long cableThe behavior is now much much better.Anyway, this is just a proof of concept. The final product will have a decent layout board with the antenna being at list 10m away from the board.Thanks a lot!
Radio coax - Page 1
Forum section: electronics / projects

author: orbiter
author_rank: Frequent Contributor
timestamp: October 04, 2013, 04:42:54 pm
content: Hi all,Is there a special name for very small gauge radio coax cable? I'm currently repairing a few DAB radio's andthe coax in them is real small scale. The outer diameter is about 0.7mmThanksorb

author: orbiter
author_rank: Frequent Contributor
timestamp: October 04, 2013, 04:58:25 pm
content: It's ok, I found it.Micro/miniature coax

author: orbiter
author_rank: Frequent Contributor
timestamp: October 13, 2013, 05:09:28 am
content: New screen was £12 from Roberts.Ended up buying a faulty radio from eBay (£6) and using the screen from that, worked like a charmSent from my HTC Incredible S using Tapatalk Pro.
Radio Duty Cycle Question - Page 1
Forum section: electronics / projects

author: Wilksey
author_rank: Super Contributor
timestamp: August 29, 2014, 10:55:06 am
content: Hi,Can someone please clear something up that I have been wondering for a while?I have several 869MHz transceiver modules, 500mW which is capable of around 1km with a decent directional antenna, I have 4 of these working as a control system for home automation experiments.Setting aside the fact I could use a lower power module, the higher powered ones were cheaper in this case as a bulk buy from Ebay, I have read several specs that state that we have to abide in the UK (and Europe) by a 10% duty cycle, it doesn't make it clear if this is per device or per system.For example, the controller sends a "heartbeat" message every 250ms and the transmission burst lasts for 11ms, the sensors (switches, lamps etc) send their response on a random radio "slot" within 200ms of receiving the message from the controller which lasts for 6ms.I have calculated that 11ms every 250ms is roughly 4.5%, and 6ms every 250ms is roughly 2.5%Now, does this mean that the 10% limit is on the entire combined calculated percentage of the system (for ex, 2.5% * 3 + 4.5% = 12%), or does it mean that as long as each device is below 10% it will be OK to use?Thanks!

author: fcb
author_rank: Super Contributor
timestamp: August 29, 2014, 11:09:42 am
content: From what I understand it's per device.

author: PA0PBZ
author_rank: Super Contributor
timestamp: August 29, 2014, 11:20:48 am
content: It is per device, but please have a look at the following:(fromhttps://www.eevblog.com/forum/projects/duty-cycle-requirements-for-ism-band-radio/where we discussed this also.

author: Wilksey
author_rank: Super Contributor
timestamp: August 29, 2014, 11:38:42 am
content: Hi,Thanks for the responses.PA0PBZ,I have the TI app note, what does it define as "on" though? The device being powered on?If so, then it will be on constantly but after 11ms of transmit time, the remaining time of the 250ms is in listening mode (even longer in listening mode for the sensor end).Does that mean then, that for a period of 1 hour I can only power the radio module for 6 minutes or I can transmit for 6 minutes (not continuously)?I thought that it only applied to transmit as when something is listening it isn't really doing any harm, but maybe I am wrong?Thanks

author: PA0PBZ
author_rank: Super Contributor
timestamp: August 29, 2014, 12:03:22 pm
content: 'ON' is the transmitter being on, so you're good.

author: Wilksey
author_rank: Super Contributor
timestamp: August 29, 2014, 12:36:49 pm
content: Thank you for the clarification!Much appreciated.
Radio Electronics on Archive.org - Page 1
Forum section: electronics / projects

author: krivx
author_rank: Frequent Contributor
timestamp: June 05, 2013, 03:16:20 pm
content: I wasn't sure which forum to put this in but I guess it counts as "projects". It looks like Radio Electronics from 1980 onwards have been archived on Archive.orgCode:http://archive.org/details/radioelectronicsmagazine

author: codeboy2k
author_rank: Super Contributor
timestamp: June 06, 2013, 01:10:31 am
content: Nice.The internet archive has been around for a long long time, and it has been useful to me as a resource to go to when ever I want to resurrect something that has gone missing from the net... dead links really suck when you find something useful and you want to read it.If anyone deserves funding, it's these guys... they have fought to be designated a "library" not a pirate that skirts the laws and steals copyrighted information.. they are truly an archive of fleeting data... and they deserve to be around.It's a fantastic effort and a great resource.

author: krivx
author_rank: Frequent Contributor
timestamp: June 06, 2013, 12:13:59 pm
content: The forums software is mangling the URL for some reason. Here's the correct one:Code:http://archive.org/details/radioelectronicsmagazine

author: vk6zgo
author_rank: Super Contributor
timestamp: June 06, 2013, 01:20:58 pm
content: Quote from: wilfred on June 05, 2013, 11:34:33 pmAnyone who wasn't in kindergarten back then!
Radio Yaesu problem - Page 1
Forum section: electronics / projects

author: tim510
author_rank: Contributor
timestamp: June 06, 2012, 10:12:50 pm
content: Hello all,I'm using a Yaesu VX-3R for a school project. To power the radio for testing purposes, a power supply simulating batteries and a custom pcb to condition the output power is used. The way the radio was connected to the custom pcb was by clipping onto the the prongs where the battery metal contact (+ -) pads push against the stock battery. The photo below show this.After some time ( maybe like a month or lees) it stopped Tx/Rx when connected using the mic/sp port. However it does Tx/Rx when using the ppt button. One thing that did happen a few times was a short circuit across the metal frame of the radio because of sloppy connections. Not sure if that is to blame. We have used another radio to confirm that the rest of the setup is working.Any ideas why the mic/sp port would stop working?

author: Zad
author_rank: Super Contributor
timestamp: June 07, 2012, 12:06:49 am
content: Bad connection on the mic/speaker port, or cable, or in the microphone unit itself?

author: w2aew
author_rank: Super Contributor
timestamp: June 07, 2012, 03:04:52 am
content: Not sure about that rig - but on some of the HTs, the mic/speaker port is programmable in the menu system to be mic/speaker, or a digital interface for programming. You may need to check the manual or menu for this to see if your's is programmable, and if it got changed.

author: tim510
author_rank: Contributor
timestamp: June 08, 2012, 05:17:14 pm
content: I think the bad connection could be ruled out since it was tested with other radios. I will check if it's programmable. Thanks.

author: MikeK
author_rank: Super Contributor
timestamp: June 08, 2012, 09:49:35 pm
content: That radio requires a special 4-conductor phone plug. If you use a regular 3-conductor (stereo) plug you'll short it out and it won't work. Are you using the proper mic, or is it something homemade?

author: tim510
author_rank: Contributor
timestamp: June 09, 2012, 12:52:53 am
content: I looked in the manual but didn't find anything on programming the mic/speaker port.The plug that we are using is the 4-conductor type. The vx-3r radio was swapped for a vx-2r. It's nearly identical and it works so I think the rest of the system is working properly.
Radiometer Wave Analyzer Type FRA3 1965 test and teardown - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: May 09, 2022, 09:08:12 am
content: wow this unit is from 196510Hz to 60kHz harmonic analyzer, really cool mechanical construction, you got to see the main adjustable capacitor !!https://youtu.be/-fPKqbIIHrsclearly they understand a very important thing : if you make the mechanical construction solid and stable,you also get good stable performance of sensitive analog circuits.but how solid.. is too much ?? how heavy ?? must it be to be too much :-)
RadioShack - Page 1
Forum section: electronics / projects

author: jwflammia
author_rank: Newbie
timestamp: February 14, 2015, 01:49:02 am
content: 70 percent off Arduino today. I bought stuff I don't need.I once bought a 2 meter transceiver kit from RS. Still have it.I remember testing tubes at RS. Hey I'm not that old.I still build tube circuits.
rail splitter for 2-wire loop powered - Page 1
Forum section: electronics / projects

author: kobena
author_rank: Newbie
timestamp: December 06, 2019, 07:29:12 am
content: I know how to split voltage using the ubiquitous TLE2426 and opamp. My challenge is splitting a loop powered supply employed in industry with a +24V supply. Any ideas?

author: David Hess
author_rank: Super Contributor
timestamp: December 06, 2019, 05:24:29 pm
content: Current looped powered means that there is a shunt voltage regulator at the load to control the voltage. At that point any standard rail splitter circuit can be used. Usually the rail splitting is done as part of the shunt voltage regulator.

author: kobena
author_rank: Newbie
timestamp: December 06, 2019, 06:17:23 pm
content: Thanks...i get what you mean and did a quick test. Most grateful
Rail-to-rail I/O programmable gain amplifier with differential input - Page 1
Forum section: electronics / projects

author: conducteur
author_rank: Regular Contributor
timestamp: March 10, 2018, 09:40:11 pm
content: I need to amplify a differential signal and control the gain with a microcontroller. Both the positive and the negative input signal are between 0 to 5V to ground... Voltage gain should be between 1 (or less) and maximum gain at least 100 times. It's not required to control the gain in precise steps ("scope" gains of 1,2,5... or binary 1,2,8, or even decimal 1,10,100,1000 is ok). The output is single-ended. If possible, i want to supply the amp with +5V and -5V, so rail to rail capability on the input and output is required in that case. The gain-bandwith product is also important and should be at least 1MHz.I searched the hole day to find a solution for my problem. I have searched on the websites of Linear, TI, Analog, Maxim, and I have read several datasheets, but didn't find a solution for my problem...Many instrumentation amplifiers have a gain that can be set with a single resistor. The gain is than G = 1 + R1/R2, where R1 is an internal resistor. As a result the gain is always more than one...Maybe there's someone here who had a similar problem and know how to solve this?

author: Wimberleytech
author_rank: Super Contributor
timestamp: March 10, 2018, 09:55:49 pm
content: Check out the AD624. It is pretty close to your requirements.
RAKON STP2746B LF 10MHZ OCXO datasheet - Page 1
Forum section: electronics / projects

author: PU1PBE
author_rank: Newbie
timestamp: January 01, 2018, 10:27:38 am
content: Does anybody know where I can find the datasheet of the RAKON STP2746B LF 10MHZ OCXO?I tried the Rakon site without success.

author: woodchips
author_rank: Frequent Contributor
timestamp: January 01, 2018, 04:26:07 pm
content: Their Lincoln UK site closed about 3 years ago, I went to the auction. Might have the software for a crystal oscillator tester, everything else has been binned.
ramp current using MOSFET - Page 1
Forum section: electronics / projects

author: electros6
author_rank: Regular Contributor
timestamp: September 23, 2014, 10:31:08 am
content: Hi guys,I am designing electronic load for my own. while go through the service manual of agilent 606X I noticed programmable slew rate. not very useful for hobbyist like me but I thought why don't try to do electronic load with slew rate control. To test I fed a triangular wave from my function gen an at 1Khz put a driver and power up the MOSFET gate and drain from 12V DC. I notice the current is not raising that much fast as my triangular wave ramp. can somebody tell me relation between current that gate needed to ramp in specific A/us or A/ms.

author: Marco
author_rank: Super Contributor
timestamp: September 23, 2014, 10:45:25 am
content: The equations are on Wikipedia. It's not very linear, but it also varies between devices, with temperature and with Vds. That last one could be fixed with a cascode, but I'd try to do something like this with a closed loop controller (ie an opamp a current shunt and feedback).

author: ajb
author_rank: Super Contributor
timestamp: September 23, 2014, 02:31:25 pm
content: A MOSFET is basically a resistor whose resistance is determined by the amount of charge that's been driven into the gate. Because the Drain-Source channel acts like a resistor, you can't control the current though a MOSFET without a closed feedback loop that senses the current and drives the MOSFET gate accordingly. If you can't control the steady state current through a MOSFET with an open loop, then you certainly can't control the slew rate in an open loop.What you need to do is drive the MOSFET gate with an opamp and have a current sense amplifier driving the inverting input of the op amp with your control voltage (from your function gen if you like) fed into the non inverting input. This is the basis of any constant current load. Note that the opamp that drives the FET will likely need to have a high slew rate and may need a voltage follower in order to charge and discharge the MOSFET gate quickly enough to achieve useful regulation, especially if the FET has a substantial gate charge.If you don't need to actuallycontrolthe slew rate of the FET, but justlimitit to provide a soft start, then you can put a resistor in series with the gate to limit the rate at which the gate can be charged and discharged. You'll need to consult the datasheet for your MOSFET as well as the device that drives it (or link them here) to size that resistor.

author: rx8pilot
author_rank: Super Contributor
timestamp: September 23, 2014, 08:04:34 pm
content: A soft start is fairly easy, but using a FET for linear current control will create huge amounts of heat. You would need a very oversize FET compared to the current you plan to use along with a good way of dissipating the heat.
Ramp generator circuit - Page 1
Forum section: electronics / projects

author: strawberry
author_rank: Super Contributor
timestamp: October 06, 2020, 08:23:11 pm
content: How to make ramp generator to stop at any given voltage level?Must be single supply circuit.Input digital selector.Output linear up positive rising dv/dt signal.

author: moffy
author_rank: Super Contributor
timestamp: October 07, 2020, 09:41:22 am
content: You can use a DAC driven by an up counter. Use a comparator to detect the stop voltage. You can use an integrator (opamp: Google it) and again a comparator to detect the stop voltage. Which depends on a number of factors.

author: strawberry
author_rank: Super Contributor
timestamp: October 07, 2020, 10:54:31 am
content: https://www.edn.com/linear-ramp-generator-uses-one-op-amp/https://www.edn.com/integrator-ramps-up-down-holds-output-level/component count

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 07, 2020, 03:43:51 pm
content: Quote from: moffy on October 07, 2020, 09:41:22 amYes, given the OP's requirements include a digital control (of, I'm assuming, the max output voltage of the generator... maybe also the slew rate? we don't know), just using a DAC for the ramp generation is certainly the easiest here. If the required slew rate is not ultra high, this could be easily done with a small MCU and a DAC. Oh and some MCUs include DACs too. Take a mid-range STM32 for instance (some have 2 embedded 12-bit DACs), and you're basically done for a few dollars and a few tens of lines of code. Very flexible too.Unless there was a strict requirement for a very high slew rate and/or high accuracy (that would require a very fast and expensive DAC), which could make an analog generator cheaper, I don't really see a point of designing an analog ramp generator here (especially since designing one that is both fast an accurate and would meet or beat a DAC-based solution is definitely not trivial), then using a DAC to control a threshold at which the ramp generator would stop. Sounds crazy these days (or would sound like a school assignment otherwise.)Just my 2 cents - of course we may be missing some hidden requirements that would make my proposal not adequate.
Ramsey PS-2 Audio Multiplier manual needed. - Page 1
Forum section: electronics / projects

author: CaptDon
author_rank: Super Contributor
timestamp: March 19, 2022, 02:34:42 pm
content: I was given a Ramsey PS-2 audio frequency multiplier. It is in working condition. I added a pilot LED so you could see at a glance if it was powered on or not. I really only need the specs, frequency range, input level, etc. Thanks in advance for any help!!
Random all outputs low in system - Page 1
Forum section: electronics / projects

author: robijn
author_rank: Newbie
timestamp: September 15, 2020, 04:47:21 pm
content: HelloI have a simple circuit I've been using for over a half year to control my electricity and my door lock.But I have the problem that when I use inductive loads that all my outputs sometimes go low.I tried to solve this by leaving space between the 230V cable and 24V cable, using optocouplers, placing capacitors on the 24V wires to the relays, using a 230V filter and 5V capacitors and I switched the PIC16F887 with an Arduino but nothing worked.Can someone help me?Schematic in attachment.Robijn Ameye

author: RoGeorge
author_rank: Super Contributor
timestamp: September 15, 2020, 05:10:31 pm
content: Most probably some spikes produced by switching inductive loads manage to reset the microcontroller. The spikes can arrive to the microcontroller either directly through wires (from the 230V mains through the power supply) or induced in some other long wires that are connected to the microcontroller, like the 1m or so wires that are going to the door lock. Can be tested by disconnecting (near the PIC side) any long wires that are connected directly to the pic.Most probably the spikes are getting in through the power supply path, try adding some filtering on the mains power cord, near the microcontroller side. Another thing to do will be to put some 100uF and 100nF (both of them) in parallel with the 5V, as close as possible to the PIC power pins.

author: robijn
author_rank: Newbie
timestamp: September 17, 2020, 04:06:24 pm
content: I have tried your suggestions.I added the capacitors and disconnected the door lock.I also removed the fuse so my system isn't connected to mains and runs on the battery.The only wires on the PIC are from the optocouplers and the switches.With all these modifications I still have the problem. Slower but I got it still.Sometimes i have 1/3 of 2/3 turning off to.Changed schematic in attachment.Robijn Ameye

author: RoGeorge
author_rank: Super Contributor
timestamp: September 17, 2020, 05:52:15 pm
content: That's strange. Maybe there is some ground loop somewhere.Another thing I would try is to separate the 5V area, and use a battery only for the 5V (for example one of those battery powered USB chargers) just to see if the defect goes away. If it still happens, there's not much you can do other than maybe shielding the microcontroller board, but this would be a little too extreme.If it works normally with a 5V battery power (completly separated from any mains or ground wires) then you can try adding a filter between the 5V power supply and the microcontroller board (on both wires, maybe some ferrite beads as EMI suppressors, too, like the big one on the left at the beginning of this video).Also, twisted pairs of wires are more resilient to interference than parallel wires. A picture with all the wirings might help.
Random LED flicker with thyristors in circuit simulation? - Page 1
Forum section: electronics / projects

author: DavidR357
author_rank: Newbie
timestamp: December 21, 2014, 09:55:27 pm
content: I'm working on a project, and am simulating the circuit in Circuit Wizard. I have a setup with transistors activating thyristors (see image).The LED's are lit by a decade counter. The problem is every now and them (seemingly randomly) when a certain LED lights up, they all flicker. It is not the same LED, and it is not all the time. I do not know if there is a problem with the circuit, or if it is just the program creating this. Also, it is fairly common for LED's to be lit by a transistor with no voltage at the base (again, seemingly random).The circuit may seem a bit odd in places (e.g. odd transistor placement), but it is not finished and everything there is needed. I de-cluttered it for this image, I replaced most of the circuit for switches (and this did not fix the problem).The project is the arcade game stacker, but I want to try to make it without using a microcontroller. By this I mean that I want it to work via logic gates and counters within the circuit.Just for reference, the 555 circuit is just an astable pulse generator, and the other chip is a 4017B decoded decade counter.Thanks!

author: Falcon69
author_rank: Super Contributor
timestamp: December 21, 2014, 09:57:54 pm
content: you may need to put a debounce circuit on those switches.Also, I don't see a 0.1uF cap on the IC's power input.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 22, 2014, 01:23:14 am
content: I see a couple things wrong with this, but I can't decide if it's the poor schematic layout or actually the circuit itself.Can you reduce this to the simplest case, with just one or two row/col drivers or whatever?And why would you choose thyristors at all? For anything?Tim

author: Falcon69
author_rank: Super Contributor
timestamp: December 22, 2014, 01:33:44 am
content: he's probably needs a latching thing done to them. I was going that route before with another circuit I was doing. I finally said screw it and did Logic Gates / mosFET combination. (a different circuit then one you helped me out with Tim)I had so many problems with those things, doing exactly what the OP is describing, random LED's lighting, that I just gave up.

author: Zero999
author_rank: Super Contributor
timestamp: December 22, 2014, 10:37:57 am
content: It can't be any layout or de-bouncing issues because he is talking about simulation, rather than the real thing.He says he's using Circuit Wizard which is just an education program. I suspect that as well as poor design practise is to blame.I suppose the question is: what is this supposed to do? There's bound to be a simpler, more effective solution, other than using a microcontroller or other programmable device.
Random pixels on ssd1306 (worked earlier ?) - Page 1
Forum section: electronics / projects

author: jawa_master
author_rank: Contributor
timestamp: September 21, 2023, 07:17:49 pm
content: I am making a wristwatch with one of the default oled screens, but with the flat-flex soldered directly to the board. I had a problem where the screen wasn't found, which was because i had left the reset pin floating. But after shorting it to 3.3v, it worked.It did so for 3 days, until it suddenly started showing ONLY random dots. I soldered up another board, and got the same issue. I have done all sorts of resets and power cycles, but to no awailCommands such as “scroll” and “invert screen” still works on these random dots. And also, the address of the screen shows up in an I2C scanner.Looking up the problem on the internet, I mostly find people who had SH1106 screens without realizing, but i doubt this applies to me, as it worked for three whole days

author: DavidAlfa
author_rank: Super Contributor
timestamp: September 21, 2023, 08:15:19 pm
content: Do other simple commands work, like screen ON/OFF?What's the i2c frequency and the pullup resistors values?Test the resistors / capacitors, it's easy to crack them when soldering them by hand, and can get really hard to detect visually.

author: jawa_master
author_rank: Contributor
timestamp: September 21, 2023, 08:21:27 pm
content: I’m on a school trip, but i will try this tomorrow 👍but I’m guessing it will work, like the other commands. It seems to be something with writing to the screen buffer

author: RogerThat
author_rank: Regular Contributor
timestamp: September 21, 2023, 08:28:48 pm
content: It's over one years since I programmed one of these but from the top of my head....I've found the chip to be a bit sensitive to signal quality. Before writing to the display I pause the whole system for 1ms(to quite down the noise) and I'm running I think 1/2 of the maximum clock speed on the SPI interface.If I get random pixels now days it's because the FPC cable is not properly seated in the contact.

author: DavidAlfa
author_rank: Super Contributor
timestamp: September 21, 2023, 08:28:56 pm
content: And no code was changed? Show the framebuffer code.

author: jawa_master
author_rank: Contributor
timestamp: September 21, 2023, 09:11:22 pm
content: No changes. I am using the standard ssd1306 library from adafruit. It shouldn’t be related to my code, as i have tried with the example codes and other SSD1306 libraries, and the trouble persists. I will however try reducing the clock speed, and pausing as mentioned above
range switching on a multi-op amp (extended bandwidth) gain stage - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: March 02, 2014, 08:01:35 pm
content: So I need to do range switching on an input signal that is multiplied to high gains using a op-amp cascade to increase bandwidth. I need four ranges.One way I thought to do it is to just put four op-amps with the same gain and tap them off with switches, so I can select the output of OPA1,2,3,4.The other way is to use many more switches (I guess 4 per op amp, which is not THAT bad, and this way I don't need four OPA (the gain bandwidth product requirement is satisfied with 2 op amps really).Have you guys seen either of these methods used in actual designs? I am not worried about the op-amp noise in particular. Using four equal gain op-amps and tapping them off seems like the best solution even though I only need two.I need at least two op-amps, unless you have a 20 GHZ op amp.
Rant: TI app note links are broken? - Page 1
Forum section: electronics / projects

author: cellularmitosis
author_rank: Unknown
timestamp: April 14, 2017, 02:00:58 am
content: Has anyone else noticed this?For example:http://www.ti.com/lit/ml/sloa079/sloa079.pdfis 404'ing.There is a search box on their 404 page. If you search for sloa079.pdf, it points you back to the broken link!So frustrating! How the hell did this change make it into their production website without getting caught? Do they have zero QA process? Sheesh!

author: electrolust
author_rank: Unknown
timestamp: April 20, 2017, 09:02:03 am
content: it happens occasionally. their site update process must be shite.

author: Fungus
author_rank: Super Contributor
timestamp: April 20, 2017, 11:40:18 am
content: TI's page is frequently broken, yes.(I don't know what testing process they use, but)

author: David Hess
author_rank: Super Contributor
timestamp: April 20, 2017, 05:44:27 pm
content: TI's web page is pretty poor and often has broken links; their selection guides are almost useless and often do not include older parts which are still in production so in order to find them, you have to know the part number and sometimes even that does not work.I liked National's site much better but of course TI erased it even before they started editing and erasing all of the old National documentation.

author: Bud
author_rank: Super Contributor
timestamp: April 20, 2017, 06:00:54 pm
content: It seems to be popular these days the vendors revamp their web sites to use the latest stupid web coding technologies to render their sutes clise to unusable . Arrow, ADI, Altium, keysight are a few to name. Linear Technology seems still holding the fort, but not sure for how long.
rar extractor - Page 1
Forum section: electronics / projects

author: raptor1956
author_rank: Frequent Contributor
timestamp: March 10, 2017, 03:24:50 am
content: What are some decent options for rar extractors that don't install crap? There are lots of options out there but it's hard to know before hand if they come with a hidden surprise.Brian

author: Mr.B
author_rank: Unknown
timestamp: March 10, 2017, 03:28:23 am
content: What OS?Windows: 7zip can extract RAR. Cannot create though.No hidden nasties.http://www.7-zip.org/

author: georges80
author_rank: Frequent Contributor
timestamp: March 10, 2017, 03:33:14 am
content: peazip works well.http://www.peazip.org/cheers,george.
Rare 1970s playart electronic Yellow Canary Toy - Page 1
Forum section: electronics / projects

author: jonovid
author_rank: Super Contributor
timestamp: July 24, 2023, 08:49:13 am
content: rare 1970s playart electronic canary toy made in Hong Kong - "patent pending" see the back of the case.2x 2SB187 SANYO germanium PNP transistors on the psbcurrently its not working. my assumption is bad electrolytic capacitors.powered by a 9 volt battery.currently reverse engineering the toy so I can repair it.My questionsdoes anyone know anything about this playart yellow canary toy? I find nothing about it online.anyone know anything about were playart made its electronic toys in Hong Kong?its value when working. & No its Not for sale.

author: Zero999
author_rank: Super Contributor
timestamp: July 24, 2023, 09:32:54 am
content: What makes you think it's the capacitors? I doubt it.Have you checked the connections to the battery and speaker?The last time someon made a thread about this, it was the speaker which was faulty. This doesn't necessarily mean it's the case here.https://www.eevblog.com/forum/beginners/repairing-a-family-heirloom-the-electronic-canary/msg3363118/#msg3363118

author: jonovid
author_rank: Super Contributor
timestamp: July 24, 2023, 10:36:29 am
content: Quote from: Zero999 on July 24, 2023, 09:32:54 amthank you for the linkno the 0.2 watt speaker ok the multimeter constantly beeps throw the speaker.battery clip is okimages was posted before I used some circuit board cleaner.currently reverse engineering circuit board

author: SeanB
author_rank: Super Contributor
timestamp: July 24, 2023, 12:47:26 pm
content: Check transformers for continuity, and then suspect those Ge transistors, as they can get very leaky with time, especially as they likely were not exactly the best performers of the batch even when new, as toy products would often buy the lower cost poor performance transistors (exactly like Sinclair did) and test them all to see if they had low enough leakage to work here, and then use them, and replace if the gain was just too low.

author: Zero999
author_rank: Super Contributor
timestamp: July 24, 2023, 01:46:22 pm
content: I bet the circuit is similar to the one in the thread I linked to above. It will probably work with silicon PNP transistors.

author: jonovid
author_rank: Super Contributor
timestamp: July 24, 2023, 07:50:35 pm
content: Quote from: Zero999 on July 24, 2023, 01:46:22 pmtrue if all else failshowever I will to get this lot fixeda lifted track on the pcb and do some re soldering
Raspbarry Pi I/O hat - Page 1
Forum section: electronics / projects

author: luudee
author_rank: Frequent Contributor
timestamp: July 15, 2023, 03:00:54 pm
content: Thought this might be of interest.The Raspbarry Pi has lots of nice I/Os coming directly from the CPU, that are fixed at 3.3V (I believe they are all 5V tolerant).Well, that wasn't good enough for me, I added some level shifters, and brought out the interfaces. This is the result !Cheers,luudee

author: wasedadoc
author_rank: Super Contributor
timestamp: July 15, 2023, 03:05:03 pm
content: Quote from: luudee on July 15, 2023, 03:00:54 pmAnyone who puts that belief to the test will discover that it is not true.

author: Infraviolet
author_rank: Super Contributor
timestamp: July 15, 2023, 05:19:08 pm
content: Is your level shifting method appropriate for all use cases of a pin? Some methods I've seen can work for pins serving as inputs only, or only for pins serving as outputs, but won't handle both uses. Or can handle inputs with pullups/downs of some particular strength, but can't handle use cases where you need a pin to float at certain times.

author: luudee
author_rank: Frequent Contributor
timestamp: July 16, 2023, 03:41:15 am
content: Quote from: Infraviolet on July 15, 2023, 05:19:08 pmHi,"appropriate for all use cases" most likely not!I designed it to be useful and meaningful to me - but I do hope others will find it helpful and useful as well!You can see the schematics and PCB layout here:https://oshwlab.com/luudee/rpi-i-o_hatCheers,luudee

author: MarkS
author_rank: Unknown
timestamp: July 16, 2023, 11:39:38 am
content: You should consider theTXS0108just for your own piece of mind. It would really suck to destroy a Raspberry Pi due to a simple oversight.

author: luudee
author_rank: Frequent Contributor
timestamp: July 16, 2023, 12:40:30 pm
content: Quote from: MarkS on July 16, 2023, 11:39:38 amThank you, Mark, this would definitely be a better choice for GPIOs and I2C.If I ever revise this baby, I will consider this part ....Cheers,luudee
Raspberry 1Ch NAT switch for IPv6 - Page 1
Forum section: electronics / projects

author: vidgeek897
author_rank: Newbie
timestamp: June 27, 2017, 01:56:38 pm
content: Hi guys, I havehdmi modulatorwith Web GUI NMS and I have dedicated static IP, I want to organize remote access from WAN. So i need NAT/PAT service, I have raspberry can I use it for NAT? If yes, can you recommend me libs for python or C (gnu) or maybe I can use ready solution for NAT. Thanks!

author: alm
author_rank: Super Contributor
timestamp: June 27, 2017, 02:18:17 pm
content: First, yes, a Raspberry PI running Linux can do NAT/PAT. Search for iptables (or its various front-ends). But why would you not do this on the router that you likely already have for internet access? Second, why would you need NAT for IPv6? If you get IPv6 connectivity from your access provider, they should really give you a subnet (/48 or /64) so you can give all devices on your network a public IP. Just set up the firewall of your router to allow traffic to the encoder at whatever port it uses.
raspberry pi a+ overclock to 1GHz???? - Page 1
Forum section: electronics / projects

author: rickselectricalprojects
author_rank: Regular Contributor
timestamp: January 30, 2015, 12:56:06 pm
content: hi everyone!i recently got the raspberry pi a+ but still use my b+ more because it is more tidy and has more ports etc. and i was on the raspberry pi website and i saw this thing saying that you can overclock your pi to 1GHz. it also said don't expect your bcm2835 to live for very long because it will reach up to upto 85 degrees Celsius.has anyone done this? should i do this or will there be a big burn mark on my floor?yes i know that i will have to use thermoelectric coolers to keep it slightly cool but has anyone done this and if so is it worth it?thanks!(PS don't be to harsh because i am only 14 and i dont know everything)

author: Skimask
author_rank: Super Contributor
timestamp: January 30, 2015, 01:04:38 pm
content: http://lmgtfy.com/?q=raspberry+pi+overclock
Raspberry Pi and PWM  - Page 1
Forum section: electronics / projects

author: XaviPacheco
author_rank: Regular Contributor
timestamp: August 23, 2018, 12:24:40 am
content: Hello,I've heard that PWM from raspberry is not so "good". I really don't know if it's true or not. Is the Pi good for controlling the speed of a small DC motor? I would like to control the speed a 20V DC motor. I can do all the research by myself. This question is basically to know what you think about it, or if you have done this before. I've always used PWM from other microcontrollers, never from the Pi.

author: moffy
author_rank: Super Contributor
timestamp: August 23, 2018, 12:44:07 am
content: They have done some extremely high frequency PWM on the PI, they built an FM tramsmitter. So PWM on the PI is OK, but cheaper and easier alternatives are the Arduino UNO/Nano. Dollars vs 10's of dollars and the Arduino programming environment is very easy to use.

author: Ian.M
author_rank: Super Contributor
timestamp: August 23, 2018, 12:48:27 am
content: It depends how you handle the PWM.Assuming you are using Python, the native GPIO module's GPIO.PWM() function is software PWM. Anyone who's ever scoped a GPIO.PWM signal or even set the frequency to within the audio range and listened to it on a speaker, will be aware how rough the result is, as other threads vary the CPU load and thus the latency of the PWM thread. Basically, it sucks and any motor you control with it will twitch worse than a hyperactive kid on a sugar and caffeine high!Personally I've moved away from using the native GPIO module and switched to using the pigpio library, which is much much better at generating low-jitter PWM (and other waveforms) as it uses hardware timer interrupts.http://abyz.me.uk/rpi/pigpio/python.htmlIf you are using C and don't want to have to delve into the depths of the Linux kernal, priority levels and BCM283x register level programming, then the pigpio library is still (IMHO) the best bet.

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: August 23, 2018, 12:57:51 am
content: For PWM on the RasPi I would recommend checking out thepigpio library. It is far superior to RPI.GPIO and WiringPi. Also software timed PWM in pigpio seems to be quite accurate.The board has only a couple hardware timed PWM pins available, software timed PWM can occasionally be quite a struggle.

author: XaviPacheco
author_rank: Regular Contributor
timestamp: August 23, 2018, 12:58:56 pm
content: Thanks for your comments. I will try the pigpio library. I guess I will have to use a logic-level FET for this purpose, due to the Pi GPIO voltage (3.3V)
Raspberry PI Based DAC - Page 1
Forum section: electronics / projects

author: electro_pt
author_rank: Newbie
timestamp: August 27, 2016, 02:26:21 pm
content: I just got a new raspberry PI 3, and have been using it as a small TV based computer. However as is often the case, once you have flexible hardware you start looking for other things to do with it. I have been intrigued by the high speed one can switch the GPIO pins, and thought there might be potential for a DAC.I know there is hardware already out for this, but I was interested in learning to do it myself for the experience. Any suggestions or recommendations. Perhaps a R-2R? Maybe an RC circuit on the output of a pin...a bit like Raspberry's RCA audio out but perhaps with higher dynamic range? Custom waveforms would be ideal, perhaps with 0-20MHz range. Just starting in this sort of thing so thought it would be a good project to learn.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 27, 2016, 05:47:09 pm
content: Beaglebone Black can do it. It has I/O coprocessors that can easily handle 100Mhz sample rate, input or output. There's even a logic analyzer based around that.
Raspberry Pi Motor Library : A python 3 library for various motors and servos to - Page 1
Forum section: electronics / projects

author: typematrix
author_rank: Contributor
timestamp: May 31, 2018, 01:37:42 pm
content: HiTWICRaspberry Pi Motor Library : A python 3 library for various motors and servos to connect to a raspberry pihttps://github.com/gavinlyonsrepo/RpiMotorLibOverview--------------------------------------------* Name: RpiMotorLib* Title: Raspberry pi motor library.* Description: A python 3 library for various motors and servosto connect to a raspberry pi.There are three categories in library.Stepper motors , Dc Motors and Servos. The following is a list of tested parts1. Stepper motor* Unipolar 28BYJ-48 Stepper motor controlled by ULN2003 driver module* Bipolar Nema 11 Stepper motor controlled by L298N H-Bridge Motor controller module.* Bipolar Nema 11 Stepper motor controlled by A4988 Stepper Motor Driver Carrier* Bipolar Nema 11 Stepper motor controlled by DRV8825 Stepper Motor Driver Carrier* Bipolar Nema 11 Stepper motor controlled by A3967 Stepper Motor Driver "easy driver version 4.4"2. DC motors* DC brushed motor controlled by L298N Motor controller module.* DC brushed motor controlled by a transistor.3. Servo GPIO PWM* Tower pro Digital SG90 micro servo* Hitec HS422 servo* Tower pro MG996R ServoThe end user can import this library into their projectsand then control the components with short snippets of code.The library is modular so user can just import the section they need.Regards

author: james_s
author_rank: Super Contributor
timestamp: June 01, 2018, 11:45:12 pm
content: Neat, I'll file that away in my things to play with folder. Thanks.

author: Ian.M
author_rank: Super Contributor
timestamp: June 02, 2018, 02:37:38 am
content: Oh dear: it imports GPIO and uses GPIO.PWM(), which is software PWM. If you've ever scoped a GPIO.PWM signal or even set the frequency to within the audio range and listened to it on a speaker, you'll be aware how rough the result is, as other threads vary the CPU load and this the latency of the PWM thread. I'd have to hook up a servo to be 100% certain, but I bet the servo is excessively twitchy.Personally I've moved away from using the GPIO module and switched to using the pigpio library, which is much much better at generating low-jitter waveforms.http://abyz.me.uk/rpi/pigpio/python.html

author: typematrix
author_rank: Contributor
timestamp: June 02, 2018, 06:12:39 pm
content: Quote from: Ian.M on June 02, 2018, 02:37:38 amYa, I am aware the servo twitching issues with RPIO , I mention it in documentation.RPIO is ok for some applications and methods. It is an issue If you need slow precise steps.At certain delays and step sizes there is twitching of the servo position.I will look into a change over from RPIO to pigpio at next update for the servo function, add it to my TODO list.