hybridfree/eevblog-posts huggingface dataset:
OTA updates of micro running freeRTOS - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: May 18, 2021, 02:52:55 pm
content: Hi,I am designing a system comprising a micro running the firmware with freeRTOS that needs over the air updates. I haven't chosen the micro yet but the client wants a Atmel/Microchip simple 16-bit.What is the simplest solution both:- software-wise (I am thinking perhaps of using Microchip's Harmony bootloader libraryand- hardware-wise, i.e. which WiFi and/or 3G module (preferably with external antenna) would you suggest and which interface to the micro?Thank you

author: jc101
author_rank: Frequent Contributor
timestamp: May 18, 2021, 05:12:30 pm
content: Harmony is for the 32bit processors, I don't think it supports 16bit devices at all. Worth checking that FreeRTOS has a port for your expected micro before going too far, if you are looking at the AWM version you might have a more restrictive list to choose from.Depending on the processor, some have live update, but you need to have double the amount of flash in there for that. Presuming you have some kind of local storage requirement, for configuration etc. you could use an intermediate loader. So you store the new image on the storage and have a small BL to just read that and update the flash.mikeselectricstuff did a video on these a while ago now, still valid though.The latest Harmony isn't too bad, and does enable some rapid development to happen. Not use the boot loader from it though.What does the system need to do, to give some idea as what to may need resources wise etc.?

author: ricko_uk
author_rank: Super Contributor
timestamp: May 18, 2021, 06:33:07 pm
content: Thank you jc101The system is a basic data acquisition for monitoring flow meters and other sensors as well actuate pumps for water services/supplies.I have spoken with the client and he is ok to use a 32-bits because fast turnaround is the priority. That means that I can use any PIC32 which I used plenty of time and also use Harmony and freeRTOS.I cannot find any freeRTOS marked as "AWM" version, what is that?What do you mean by "Not use the boot loader from it though."? Do you recommend to not use it or are you saying you haven't used it so cannot comment on it?Thank you
OTA VCR question - Page 1
Forum section: electronics / projects

author: Jan Audio
author_rank: Frequent Contributor
timestamp: April 24, 2019, 03:56:34 pm
content: Hi, i like to have a voltage controlled resistor,i am looking in the LM13700 datasheet,there is a single ended resistor schematicand there is a dual ended schematic.I dont understand what is a single ended resistor ?And the schematic is not clear to me, is the input at the + input ?, and the Vout is behind a capacitor ?, why is that ?I will try the dual ended resistor, will it give exact the same voltage at the output, or will is be different somehow ?thanks

author: Kleinstein
author_rank: Super Contributor
timestamp: April 24, 2019, 04:03:33 pm
content: The OTA can be used as a variable gain amplifier and this can be reasonably help to simulate a resistor to ground. Simulating a fre floating resistor is way more complicated. In this case I would consider something like a Photomos device like H11F1 - though this is limited to low voltage.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: April 24, 2019, 04:26:26 pm
content: Thanks, only i need 12 volt at least.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: April 26, 2019, 03:43:39 pm
content: Maybe my LM13700 is broken, it takes not a milliamp power when i connect the +the whole thing dont works.

author: JPortici
author_rank: Super Contributor
timestamp: April 26, 2019, 03:51:57 pm
content: the VCR thing works, check your wiring. You may also have a 13700 with damaged buffers (it's not unusual for that to happen)
OTDR travel time - Page 1
Forum section: electronics / projects

author: alamwte
author_rank: Regular Contributor
timestamp: February 23, 2022, 05:17:39 am
content: Hello,I am searching about OTDR (Optical Time Domain Reflectometer) system.It shows optical length in fiber. It has 3 main parts ; laser diode, photodetector and a proccessor.First ligth energy is injected by OTDR into the fiber through a laser diode and pulse generator. In the measurement the returning ligth energy is seprated from injected pulse using a Coupler and fed to the photodiode. Then it is converted to electrical energy and the proccessor measure the travel time between outgoing pulse from laser diode and incoming pulse into photodiode. Then calculate the length by knowing the speed of ligth in fiber.Now what I can not undrestand is that how OTDR measures the travel time of ligth. How it knows the time of injected pulse's time and returning pulse?Thanks,

author: ve7xen
author_rank: Super Contributor
timestamp: February 23, 2022, 05:46:26 am
content: It knows the time of the pulse because it generated it...it's strong enough through the coupler to be measured by the photodiode too.Then you use a fast ADC to sample the photodiode, but the timing requirements aren't *that* crazy. Propagation in fibre is about 5ns/m so you shouldn't need to do anything faster than 200MHz or so. Clever engineers don't need that.You can probably build a poor man's version with just the optical components, a pulse generator, a couple fast comparators, and an A->B interval timer.Dec 1988 issue of HP Journal has lots on OTDR.https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1988-12.pdf

author: alamwte
author_rank: Regular Contributor
timestamp: February 23, 2022, 11:25:29 am
content: I got it , Thank you so much

author: sunandwavs
author_rank: Newbie
timestamp: June 12, 2023, 04:44:44 am
content: Hi,I read the HP pdf on the concept of an OTDR. If I understand it correctly, a circuit injects infrared light pulses into a cable. At the same time recording time-hashes in nanoseconds, which are then logically interpreted to make several determinations. Where can I look for plans or diagrams to build a simple OTDR?

author: Terry Bites
author_rank: Super Contributor
timestamp: June 12, 2023, 06:47:53 am
content: Here's a reference design from TI which details the practical aspectswww.ti.com/lit/ug/tiduaz1/tiduaz1.pdf?ts=1686547431497It may be far too complex for an experimental design, but parts of it maybe useful to you.If you're starting from scratch, then the optics will be the hard part of this project. To transmit and recieve along the same fiber you need an optical splitter or circulator.Prices often in the $500s +! You can also find them on aliexpress for about $20, they may worth a try in a DIY experiment.For a cheap laser source you might try hacking a tranciever module see "sfp-experimenter"
Other ADC + GPIO IC's like TI ADS7128? - Page 1
Forum section: electronics / projects

author: ANTALIFE
author_rank: Frequent Contributor
timestamp: September 03, 2021, 12:57:13 pm
content: Hey AllDoes anyone else know of IC's similar to the ADS7128/TLA2518 (as in ADC + GPIO all on one package)?https://www.ti.com/product/ADS7128I know I can achieve the same functionality with an MCU, but am after an integrated solution so there are less things to program ;^)

author: thm_w
author_rank: Super Contributor
timestamp: September 03, 2021, 11:53:31 pm
content: I'm usingADS1248, but quite an old IC and different from your application.Seems like neither TI or digikey have gpio as an option in their parametric search. Probably due to it being an oddball feature..The thing is, it would be very easy to find an i2c GPIO IC driver. I'm not saying writing one for the ADC is hard, but, most likely you will need to write it yourself.So in the end it can be less programming work to use a common part.
OTM8009A TFT parallel only ? - Page 1
Forum section: electronics / projects

author: Jan Audio
author_rank: Frequent Contributor
timestamp: August 21, 2019, 04:04:26 pm
content: Hi, is there no way to use SPI for the graphics on this display driver : OTM8009A ?It is a nice display, only i dont like to use 16 pins from my 28pin DIP package MCU.thanks

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 21, 2019, 04:14:33 pm
content: Well, it appears to have an SPI interface: see:http://www.orientdisplay.com/pdf/OTM8009A.pdfNow I don't know about the resolution of the LCD panel it will drive, but expect pretty poor performance using SPI unless the panel has very low res.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: August 21, 2019, 04:28:20 pm
content: It has 800x480 pixels in full color.The SPI might be for the touch panel only.

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 21, 2019, 04:45:08 pm
content: Quote from: Jan Audio on August 21, 2019, 04:28:20 pmNope, I don't think so. See section 6.7. You can write commands and write to GRAM data through SPI. I don't think the OTM8009A controller itself handles touch panels.Now you're probably dealing with an LCD module including this controller PLUS an additional controller for the touch panel.And I don't know whether the OTM8009A is accessible through its SPI interface in your module. It may have been set to MPU parallel interface only in hardware.To check that, you need to see whether they have given access to the IM0, IM1, IM2 and IM3 lines, or if they are at least configurable via some kind of jumpers on the board...

author: Jan Audio
author_rank: Frequent Contributor
timestamp: August 22, 2019, 11:36:30 am
content: Ah i see now, different controllers.Ok, will check for those pins.The complete displays themselfs dont have a manual i guess.Maybe i should buy one.thanks

author: Jan Audio
author_rank: Frequent Contributor
timestamp: August 22, 2019, 11:48:58 am
content: So i guess this ILI9341 screen i got has no SPI control, there are no M pins :
OTS Bluetooth module with 1Mbaud Uart - Page 1
Forum section: electronics / projects

author: max_torque
author_rank: Super Contributor
timestamp: May 06, 2018, 03:53:16 pm
content: Ok, i've looked, and looked, and looked, but i just can't seem to find an Off-The-Shelf Bluetooth module that supports a 1Mbaud uart interface? Plenty have delectable baud rates up to around 3 Mb but i can't seem to find one that does exactly 1Mb.Anyone used one that does?(application is a retrospective add-on for an existing device that has a 1Mb serial bus (can't change the baud rate in the device because the f/w has already been released)
OTS enclosure for the very popular 2.8" TFT display - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: April 29, 2021, 07:21:00 pm
content: Does anyone know if an off the shelf enclosure for this very popular display is available?I will need at least a hundred so 3D printing is not a viable option.
Outdoor weather resistant GFCI dimmer? - Page 1
Forum section: electronics / projects

author: shaocaholica
author_rank: Newbie
timestamp: October 12, 2015, 06:29:15 pm
content: I want to put some string lights up outside but I want them on a permanent in wall dimmer. I was thinking about doing it this way:GFCI pass through panel > in-wall Lutron digital dimmer > Weather Resistant in wall plugAll enclosed in a weather resistant box. So the lights simply plug into the dimmer which is on the load side of the GFCI pass through and everything is boxed up nicely. Any issues with this setup?
outgassing and vaccuum ovens... - Page 1
Forum section: electronics / projects

author: Gibson486
author_rank: Frequent Contributor
timestamp: September 01, 2020, 08:26:39 pm
content: Not really electronic related, but I have a question about out gassing. Do vacuum ovens make out gassing worse? i was under the assumption that people use vacuum ovens to limit the amount of out gassing. is this wrong? Also, when I put a material in google and put out gassing next to it, it gives me mixed results. For example, searching for silicon, the first link says it out gasses alot, but other links say Nasa used it because it does not out gas as much. Which is it?

author: Kleinstein
author_rank: Super Contributor
timestamp: September 02, 2020, 09:21:58 am
content: Heat up the material will increase the rate of out-gassing while the material is hot. If done long enough the gas content can be reduced so far the after cooling back to normal there will be less gas coming out.The high temperature treatment may also change the material - some may show more out-gassing later, especially if heated to much.With silicone there are many different types. Especially silicone based plastics that can be quite different from the silicone sealant that only hardens later. The usual silicone sealant in know to out-gaz a lot and for serious vacuum it is not considered gas tight at all, more like fine filter that easily lets water vapor pass through.

author: wizard69
author_rank: Super Contributor
timestamp: September 02, 2020, 11:40:17 am
content: Quote from: Gibson486 on September 01, 2020, 08:26:39 pmIt depends upon what he oven is used for. For example heat treatment of metal under vacuum is done often to reduce oxidation. If you get a bit hotter the oven can melt the metal and under vacuum degas it. Using vacuum to degas in an oven or not is very common in industry. So yeah a vacuum can accelerate a degassing operation. I'm not sure how putting something under vacuum could ever limit out gassing as it would rather accelerate it.QuoteThat statement makes no sense to me.QuoteI guess the first question is why are you asking. Because I suspect that the details matter.

author: ConKbot
author_rank: Super Contributor
timestamp: September 02, 2020, 12:56:53 pm
content: I think some of the confusion here is a bit of difference in the meaning of outgassing. For NASA they are looking for <1% mass loss, and for <0.1% to condense on a 25C surface.For general vacuum systems you're talking about anything that can spoil your pumping efforts. So if a particular silicone picks up 0.85% moisture, it can be low outstanding per NASA standards, but still frustrating you in a vacuum system as it ourgasses water for days.
Outjob red link lines - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: December 07, 2023, 01:37:57 am
content: Hi,with reference to the attached screenshot, in the Altium OutJob file, some container link lines are green like the schematic PDF (as they should be) and some red (second screenshot).Only the Folder Structure type of container (and all of them) have red link lines.When I looked up the Altium documentation and various forums, all point to editing the Page Setup... BUT as you can see from the screenshot, it is disabled and it is disabled for all files linking to those Folder Structure containers.Any ideas on how to solve it?Furthermore, for some reason, only this project (that has the red link lines) - when generating the output for those containers - it generates the Gerbers but not the Camtastic.I remember years ago finding an option to resize the paper size of a PCB document (not a schematic document) and wanted to see if that changes anything. But cannot find where that option is. Does anybody know where that option is?Thank you

author: ajb
author_rank: Super Contributor
timestamp: December 07, 2023, 03:04:12 am
content: Variants?We had this problem recently on one computer versus another, but I don't remember what/if we figured it out properly. I feel like it might have been something to do with an output path to a mapped drive or something weird I was trying to do with parameters in output paths, but not sure about that.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 07, 2023, 05:53:07 am
content: Scroll down a lil from here:https://www.altium.com/documentation/altium-designer/streamlining-generation-of-manufacturing-data-with-output-jobs#!linking-outputs-to-output-containers-and-print-jobsI have no idea how that applies to a file output container though...Tim

author: ricko_uk
author_rank: Super Contributor
timestamp: December 07, 2023, 09:46:52 pm
content: Thank you Tim and ajb,I tried everything you guys suggested and what was mentioned in those links too. But did not solve it.Any other suggestions / ideas?Thank you
Output Capacitance in LDO and SMPS Circuits - Page 1
Forum section: electronics / projects

author: electronx
author_rank: Regular Contributor
timestamp: April 05, 2024, 10:29:56 am
content: In LDO or SMPS circuits, the maximum capacitive load is generally specified. Is the capacitance at the output of the LDO or SMPS circuit used after the SMPS LDO output also included in the output capacitance of the main SMPS or LDO?If there are additional capacitances downstream from the LDO or SMPS output, such as capacitors at various stages of a power distribution network, are nthey typically included in the specified maximum capacitive load of the LDO or SMPS itself?For easier understanding, should Capacitors C2 and C3 be included in the output capacitance load of Smps1?

author: xvr
author_rank: Frequent Contributor
timestamp: April 05, 2024, 12:44:54 pm
content: No

author: AnalogTodd
author_rank: Regular Contributor
timestamp: April 05, 2024, 02:22:29 pm
content: Quote from: electronx on April 05, 2024, 10:29:56 amThe way to look at all of this is to think about the impedances each presents. A load capacitor on the output of SMPS1 presents a low impedance at frequency and is often a major part of the stability equations for the circuit.From an ideal perspective, SMPS2 and SMPS3 do not have theirinputimpedance be a function of their output capacitance. They actually show a negative impedance as their current changes in proportion to the voltage (think dR = dV / dI). This is independent of their output capacitance and as such their output capacitors are not included on the output capacitance of SMPS1.

author: ejeffrey
author_rank: Super Contributor
timestamp: April 05, 2024, 07:41:51 pm
content: The downstream switcher does not look like a capacitance but you can't always just ignore it either. It's definitely possible with cascaded systems, especially cascaded SMPS to get stability issues because of the negative impedance of the downstream regulator. But it's a much more involved analysis than just an effective capacitance.An LDO looks like a constant current (high impedance load. So for the case of an upstream switcher and downstream LDO the stability criteria are easier.
Output capacitor in distribution amplifier - Page 1
Forum section: electronics / projects

author: jmw
author_rank: Frequent Contributor
timestamp: May 13, 2021, 03:51:48 pm
content: I'm taking apart an Extron video distribution amp with the idea of modifying it to run at 50 Ω instead of 75 Ω. Each buffer is driving 2 output channels. For each output, there's a 75 Ω resistor in series, but there's also a capacitor in parallel with this resistor. I measured the capacitor at 28 pF, exactly what you'd expect to have a bandwidth of 150 MHz (as stated in the amplifer's spec) with 75 Ω source and load, but this is not connected in a way to act as a low-pass filter. Why do this?

author: jmw
author_rank: Frequent Contributor
timestamp: May 13, 2021, 04:44:42 pm
content: Here's what happens when I take the capacitor out btw (Mem/dark yellow = capacitor placed, bright yellow = capacitor not placed). Wouldn't pay too much attention to the particular gain at any frequency, I'm using a 50 Ω spectrum analyzer and there's fixed and adjustable gain stages in the amplifier itself. Still not sure why you'd want a reactive source impedance on an output.

author: Benta
author_rank: Super Contributor
timestamp: May 13, 2021, 05:15:30 pm
content: It compensates for cable loss, which increases with frequency.
Output capacitor specification for LMZ21701 and similar - Page 1
Forum section: electronics / projects

author: daqq
author_rank: Super Contributor
timestamp: April 15, 2015, 12:39:11 pm
content: Hi guys,The TI simple switcher module LMZ21701 datasheet:http://www.ti.com/general/docs/lit/getliterature.tsp?genericPartNumber=lmz21701&fileType=pdfon page 11 and 12 provides example values for various output voltages, listing their values. For all of the output voltages it lists the voltage rating of the output capacitor to be 10 V or more, even for an output of 1.2V . Aside from removing the problem of a DC bias diminishing the capacity of the capacitor, is there any reason for this?I would like to use several 6.3V rated X7R 22uF 0805 ceramic capacitors for the voltage rails of +1.2V, +2.5V and +3.3V. For a +5V rail I would like to use several 10V rated X7R 1206 ceramic capacitors.As input caps I would like to use several 4u7 25V rated 1206 X7R caps - because that's a value we use regularly.Is there any reason for this to cause problems?Thank you,David

author: DanielS
author_rank: Frequent Contributor
timestamp: April 16, 2015, 03:08:14 am
content: The voltage rating includes ringing, switching noise, transients and any other effects that may cause the capacitor to momentarily see more than the intended DC voltage.With multiple capacitors in parallel, that should considerably reduce the ESR/ESL and consequently reduce the magnitude of any ringing so you should most likely be fine with a 30-50% margin. You will not know for 100% certain until you plug a multimeter on the PCB and look at what happens.You may want to plan some additional footprints for RC damping in case you do get significant ringing.
Output extender? - Page 1
Forum section: electronics / projects

author: Tajjbe
author_rank: Newbie
timestamp: May 25, 2020, 11:32:36 am
content: I'm doing a little scoreboard project that I now got a little stuck on and want to see if anyone with experience can help me.The scoreboard have 4pcs of 7-segment displays and a total of 22 LED's that needs to be individually controlled.The 7-seg.disp are the cathode-controlled type.Is there any type of output-extender IC that I will be able to control all leds and displays via a digital stream to or do anyone got a better exampleto control everything with my uC?Here is an example of the scoreboard to help if I explain badly

author: madires
author_rank: Super Contributor
timestamp: May 25, 2020, 12:09:09 pm
content: Do you need simple on/off operation or something more sophisticated with constant current, PWM and what have you?

author: Nusa
author_rank: Super Contributor
timestamp: May 25, 2020, 01:34:52 pm
content: "LED Display Driver" is a good search phrase for you. If you answer madieres question, someone may make a specific suggestion.

author: Tajjbe
author_rank: Newbie
timestamp: May 25, 2020, 01:55:21 pm
content: Yes as simple as on/off, something with sink output..

author: madires
author_rank: Super Contributor
timestamp: May 25, 2020, 04:31:31 pm
content: In that case a few 74HC595/74HCT595 would the job. If the 7-segment display and the 595 are powered from the same rail then a pin set to low sinks current and when set to high prevents any current flow (no potential difference). But if the 7-segment displays are powered from another rail with a higher voltage or need more current than the 595 can handle you could add transistors to switch the segments.

author: MarkF
author_rank: Super Contributor
timestamp: May 25, 2020, 04:37:54 pm
content: I love these shift register solutions...Just a little noise, one missed clock and ALL of the outputs are messed up.

author: Tajjbe
author_rank: Newbie
timestamp: May 25, 2020, 08:15:17 pm
content: Ah okey, never worked with shift register. Sounds it could help me solve this problem@MarkF, I will have that in mind when contructing the PCB
Output of AC/DC Converter? - Page 1
Forum section: electronics / projects

author: hal9001
author_rank: Regular Contributor
timestamp: April 28, 2021, 10:13:25 am
content: Is the output of AC/DC board mount converters regulated at constant voltage?For example the datasheet of CUI PBO-15C has load regulation specd but Im not clear if that means the output is regulated.Thanks

author: Zero999
author_rank: Super Contributor
timestamp: April 28, 2021, 11:29:04 am
content: The load regulation is the % change in output voltage, normally full load vs unloaded. For example, if the output voltage is 10V and the load regulation is 1%, the maximum change in voltage, between full and no load, is 10*0.01 = 0.1V.In short, those AC:DC converter board are regulated. Another sign of this is the wide input voltage range. Unregulated converters specifiy a tight input voltage range.

author: hal9001
author_rank: Regular Contributor
timestamp: April 29, 2021, 07:05:17 am
content: Quote from: Zero999 on April 28, 2021, 11:29:04 amThanks for the clarification
output of ald2332 comparator TTL compatible with dual supply? - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: June 25, 2014, 08:14:56 pm
content: http://www.aldinc.com/pdf/ALD2332.pdfIs the output of this unit when running on a dual supply +-5v going to be -5->5V or 0-5V?I ask because the LT1016 I was using before put out a 0-5v even when running on dual supplies, I am not sure if this one does too?

author: SArepairman
author_rank: Frequent Contributor
timestamp: June 25, 2014, 08:21:11 pm
content: nmv I found it
Power supply project - Page 1
Forum section: electronics / projects

author: conducteur
author_rank: Regular Contributor
timestamp: June 12, 2014, 09:30:30 pm
content: I want to make a lineair 0-1A 0-25V psu that i can use in our modelrailroad club. The work for schematics and designing the pcb is almost done.I've just want to know: how do you protect the psu output?1) I have a fuse before the transformer, and i can regulate the output voltage to 0 volts if to much current is drawn from it to prevent damage2) A diode over the lm 317, if the output voltage due to something is higher than the input i hope this would protect my design.3) A diode at the output, inverse biased of inverse voltage at the output.4).... Are there other things that i can do to prevent this project?

author: theatrus
author_rank: Frequent Contributor
timestamp: June 13, 2014, 03:59:44 pm
content: Have a schematic?

author: conducteur
author_rank: Regular Contributor
timestamp: June 13, 2014, 04:34:31 pm
content: Yes, I do have that!It's based on one single lm317. Potmeters for the voltage/current control are on a second board.My output voltage is between Vout and AGND, R9 between AGND and GND acts as the current sensing resistor.The relay is used to switch the transformer tap (a 2*12 Volt 30VA transformer).

author: dannyf
author_rank: Super Contributor
timestamp: June 13, 2014, 09:38:16 pm
content: QuoteWhat are you trying to protect against?

author: RazSlack
author_rank: Contributor
timestamp: June 14, 2014, 11:31:08 am
content: Only thing that comes up to me as a slight nuisance that might need something for the output is the fact that model trains like jumping around on their tracks, constantly terminating and reconnecting the train to the power supply. This can be somewhat stressful for a PSU, but I might be wrong, just adding my 2 cents.

author: conducteur
author_rank: Regular Contributor
timestamp: June 14, 2014, 12:58:51 pm
content: That's not the thing i want to do, but maybe I also need to take care about that problem. I think it's not likely to happen, but do i need some protection against an (external) overvoltage at the output, and other strange things that maybe can happen and damage the thing?

author: christopher iles
author_rank: Regular Contributor
timestamp: June 14, 2014, 04:55:09 pm
content: I think that you will find that the LM317 has all the protection you need already built into the device. Do not exceed the recommended input voltage and decouple the input and output with capacitors close to the regulator i.c. to prevent self-oscillation.I built one some 20 years ago and it's still going strong (it's had its output shorted out many times without any harm at all).I don't have the diode across the input/output, all I did was put 10,000uF smoothing after the bridge rectifier and decoupled the in/out pins on the '317.Hope this is of use,Chris.
output signal level shifter - Page 1
Forum section: electronics / projects

author: N TYPE
author_rank: Regular Contributor
timestamp: March 29, 2019, 06:06:01 am
content: Ive got this speedo corrector to convert my cars tacho signal.the input is a 12v square wave pulse to gnd.Theres no trouble with the input sensing circuitry, that all works fine.My problem is that the maximum output voltage swing is only 8.2V, its not enough to trigger the edge detection in my tachometer. I need this output to be at 12VIve got the circuit diagram attached.If you look at the output circuit in the lower right hand corner, Im thinking I just need to cut the trace at "A", and connect it to the 12V input. Would this be correct?Another option would be to use the standard 8.2v output to drive an external transistor connected between 12V and Gnd (with some current limiting resistors in series of course) however Id like to keep everything neat and tidy.

author: Zero999
author_rank: Super Contributor
timestamp: March 29, 2019, 09:34:05 am
content: Yes, just connect A to 12V, at the input node of the LM7805.

author: Ian.M
author_rank: Super Contributor
timestamp: March 29, 2019, 10:08:31 am
content: I recognise that! It was a Silicon Chip magazine project (republished in EPE for the UK market) from about a decade ago.Found it:http://archive.siliconchip.com.au/cms/A_108157/article.htmlNo track cuts required- just fit a fly-wire instead of LK1/LK2

author: N TYPE
author_rank: Regular Contributor
timestamp: March 31, 2019, 07:15:43 am
content: You're absolutely right, It is from silicon chip and has had several revisions over the years.One question I have is that If i run a fly wire from the lk1/lk2 common to +12v . What effect will it have on the input / sense circuitry?

author: Ian.M
author_rank: Super Contributor
timestamp: March 31, 2019, 09:08:32 am
content: Not much. If S2 is in position B the input pullup will be to 12V instead of 8.2V/5V selected by LK1/2, otherwise absolutely no effect.

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 31, 2019, 04:23:38 pm
content: You could also just remove ZD3, no wire needed. Tidy.Note that there is basic protection here. A 16V zener that will limit the voltage, but there can be voltage spikes on the +12V in some cars (especially older ones), so you could maybe replace ZD3 with a 12V zener instead. That would give added protection for the circuit you're feeding the output with (not sure what max voltage it can tolerate).Note: check the voltage rating of the 10µF capacitor if you're going to do that. If they have used a 10V cap for instance, that wouldn't be good.

author: Ian.M
author_rank: Super Contributor
timestamp: March 31, 2019, 04:38:33 pm
content: That won't work. You cant get enough current through the 220R resistor too get more than 8V output swing due to the current requirements of the 470R load on Q6 and 1K load on Q5. The only practical option is to jumper to the regulator input. It doesn't matter that its not a particularly clean 12V (probably more like 13V), as any automotive circuit designed for 12V input signals will accept the supply voltage as a high level.
Output Voltage minimal Changing in bfs - Page 1
Forum section: electronics / projects

author: Rocky Richi
author_rank: Newbie
timestamp: April 02, 2025, 12:24:36 pm
content: Hello everyone,I'm working on an electronics project that uses a flexi force sensor A201 , INA333 instrumentation amplifier and esp32 module ,and I've simulated the circuit using lt1167(in place of ina333), changing the resistance value(in place of sensor) and used behavioural voltage source (in place of adc value conversion on esp32) in LT spice.However, I'm running into an issue:when I apply force to the sensor, I observe minimal step variation in mV range in the LT1167's output voltage and no or minimal step variation on bv source valuesWhat I Have Tried So Far :1.Tried to invoke the ina333 spice models but simulation was not behaving properly.2. hence used lt1167 built in library ina which is present on ltspice platform.3. I updated circuit to resolve the issue by adding capacitors to ensure the noise is the problem.4. Later I checked for the different voltage levels but no change.5. Later I thought voltage divider may be problem and hence removed it but no effects.6. also changed r2 value and gain r3 value but it just increased the output voltage swing and bv source value.7.Also employed the opamp to provide the stable buffer to ref pin.Are there any circuit modifications or additional components that could help enhance the sensitivity of the circuit?Any suggestions would be greatly appreciated !
Outsourced projects plan - Page 1
Forum section: electronics / projects

author: steamedhams
author_rank: Regular Contributor
timestamp: May 03, 2022, 09:41:51 am
content: Hi,I am going to pay to have three projects designed by various outsourced people.I idea is to write more about these projects in detail with requirements...etc and send them everything in one gone.I will find people on Fiverr and similar websites to make the following projects.They will be the following:1) mp3 player with SDcard as memory, stm32 based, buttons to change music, audio jack, speakers..etc2) FPGA test board with breakouts on all major pins. (Characterization board for power consumption)3) led neopixel matrix board 32x32 controlled by stm32 and with breakout pins for the stm32 to connected to for other projects.My intention is not to actually have these boards made but rather to gauge the skills coming from these sources for future projects.I wouldn't be able to get anything made at the moment anyways.I'll be looking at how much input they require from me after the document has been sent.I'd like to see the quality of their work and of course.. the hidden extra costs that will likely come through this experiment.I will try and diversity my selection of the people I pick.Would anyone be interested in following this process on youtube or twitch? If so, I'll track it and upload the videos online so we can all learn something.Any keen?

author: AndyC_772
author_rank: Super Contributor
timestamp: May 03, 2022, 01:06:28 pm
content: I'm not sure what you hope to learn, if the exercise is essentially an academic one with no physical end product.For example, if you asked me to develop any of these projects, we'd spend quite a bit of time upfront exploring the project requirements in detail - things like the end user's expectations, commercial volume and product lifecycle, regulatory requirements, costs, and so on. All these things help ensure that the end product is actually fit for its ultimate purpose, not merely a thing designed to a specification. It's a two way process that's valuable to both parties, and not really something that can be substituted with a written spec unless you're working with someone who is already familiar with you and your market.Without physical hardware you'll be missing out on the embedded firmware, and the ability to test usability, functionality and reliability.Finally, you're also missing out on the main thing which (IMHO) differentiates between a good design partner and a bad one - support. Will you get a set of CAD data which is essentially 'orphaned' as soon as it's delivered? Or are you able to call up the developer some time later to ask questions, help with production, deal with any issues raised by customers, or make changes?
OV5642 camera scaling issue - Page 1
Forum section: electronics / projects

author: ksstms
author_rank: Newbie
timestamp: February 03, 2021, 10:27:43 pm
content: Hi!I'm trying to use anOV5642 camera modulewith a PYNQ-Z2 FPGA board. I made a little test project which uses DMA to write frames to the CPU's memory, and the CPU sends it to the PC via ethernet.All of this works fine, but I just can't figure out how to configure the camera properly.My goal is to use it with RAW Bayer output at 640x480 resolution for now. (On this board I can't really connect a high-frequency parallel bus, and FPS is more important than resolution)The scaling function doesn't seem to work. I always get a 640x480 pixel cropped part of the sensor array, which makes the FOV very narrow.I started by copying the configs fromArduCAM's repo. The driver itself performs a soft reset, then applies theOV5642_1280x960_RAWandOV5642_640x480_RAWconfigs. (I have attached it to this post.)This produces the cropped image. Then I started to experiment with the settings.The scaling (0x5001[5:4]) wasn't enabled, but enabling it doesn't make a difference.Subsampling would also be fine for me. The vertical subsampling (0x3818[1:0]) works fine. Horizontal subsampling (0x5002) produces a white image, both in averaging and skip mode (0x501C)I also thought that maybe the scaler can only do integer ratios, so I have set the crop window size (0x3804-0x3807) to 1280x960. That didn't help either.The OV5640 looks kind of similar, so I have checked out some configs for that, and tried to find the matching registers in the OV5642, but couldn't find any cluesDoes anyone have experience with this module? At this point, I'm thinking that maybe my camera is faulty. Can you recommend a similar module (even a lower resolution one)?

author: amyk
author_rank: Super Contributor
timestamp: February 04, 2021, 02:43:17 pm
content: These were commonly used in Androids, so perhaps searching for source code and inspecting that will give you some clues. There's also the datasheet, which is incomplete but may yield other useful hints.

author: ksstms
author_rank: Newbie
timestamp: February 04, 2021, 03:30:16 pm
content: Thanks for the tip. I've already spent 20+ hours reading the datasheet and tinkering with the settings.I have foundthisLinux driver on multiple sites. There's a comment with the bad news:Code:/** About OV5642 resolution, cropping and binning:* This sensor supports it all, at least in the feature description.* Unfortunately, no combination of appropriate registers settings could make* the chip work the intended way. As it works with predefined register lists,* some undocumented registers are presumably changed there to achieve their* goals.* This driver currently only works for resolutions up to 720 lines with a* 1:1 scale. Hopefully these restrictions will be removed in the future.*/I guess I'm going to buy a cheap OV7670 for the time being.
ov7670 test pattern and register configuration  - Page 1
Forum section: electronics / projects

author: aseok
author_rank: Contributor
timestamp: July 04, 2015, 08:20:07 am
content: HelloWhat is the output data format of ov7670 in test pattern mode(8 bar code)?is it modifiable?i tried to change it to RGB565 from it's default but it didn't affect the output.What about it's resolution in test pattern mode?I also need some working register configuration in different resolutions(e.g. QCIF).Thanks.

author: jimon
author_rank: Regular Contributor
timestamp: July 04, 2015, 01:45:34 pm
content: Hi, output format should be dictated by register settings. You should check MSB/LSB settings.

author: aseok
author_rank: Contributor
timestamp: July 08, 2015, 04:03:59 pm
content: HelloHow picture is scanned and sent in RGB565 mode?is it bottom to top of the picture or vice versa?

author: jimon
author_rank: Regular Contributor
timestamp: July 10, 2015, 11:14:29 pm
content: IIRC should be top->bottom, left->right.
Oven Controller Problem - Page 1
Forum section: electronics / projects

author: German_EE
author_rank: Super Contributor
timestamp: February 25, 2016, 12:57:41 pm
content: I have just built up the following circuit:http://techlib.com/images/ovencontrol.gifIt almost works, but not quite. By altering the temp set resistor to about 2.9 K ohms I can get the circuit to come on at 40C, just right, however it's either full on or almost off and when the circuit reaches the set temperature the voltage on the base of the driver transistor drops from 10V to 1.4VSo.....................1) Is there any way to make this into a proportional heater control where the output starts to decrease as I get near to the set point2) How do I get rid of that 1.4V offset? The OP07 is supposed to be a 'low offset' device but I'm not seeing that.

author: German_EE
author_rank: Super Contributor
timestamp: February 25, 2016, 02:51:20 pm
content: The two 22uF capacitors are in series so that's 11uF in the control loop, not 44uF. Thanks for the link though.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 25, 2016, 03:56:02 pm
content: The output of the OP07 does not work well at very low voltages, e.g. below about 2 V. So it might be helpful to have a resistor from the base of the transistor to GND and increase the 100 Ohms from the OP to the transistor a little.The controller is a kind of PI regulator. With additional filtering at high frequencies, which is in some kind is needed for a real world regulator. The Problem might be the choice of the control function (time constant and amplification) - this depends of the oven used.One weak point of the regulation is that a resistor as a heater has a square law power function, thus the regulator will have higher gain at high power and low gain a low power. So the tuning of the regulator needs to be a compromise, possibly oscillating and lots of overshoot at high power and rather slow a low temperatures. So something like a square root function between the OP and output stage might help, even if only approximate (e.g. piece-wise linear with diodes / resistors).

author: German_EE
author_rank: Super Contributor
timestamp: February 25, 2016, 05:34:06 pm
content: For now I have solved the offset problem by cheating, two 1N4148 diodes in series with the 100 ohm resistor. This now gives me an output of 0.3V (off) and 9V (on). This appears to lock the assembly within a range of 41C +/- 0.3C and I can see the temperature slowly drifting up and down within these limits, not bad for a first attempt.For now the oven assembly is on test but tomorrow I might try that resistor from base to chassis and increase the 100 ohm resistor. The ultimate cheat would be to use a microcontroller to read the thermistor then PWM the output but I prefer an analog solution.
Oven Reflow Controller (Rocket Scream) - Page 1
Forum section: electronics / projects

author: Mephitus
author_rank: Regular Contributor
timestamp: March 11, 2016, 04:30:16 pm
content: Full overview from original designer:http://www.rocketscream.com/blog/docs-item/reflow-controller-shield/#tab-id-1Yeah yeah, I know its effectively a kit. But I had to make a quick post about this nifty little oven controller shield setup.My shield was was put together and donated by forum userFat(Thanks again dude!). The solid state relay needed to make this connect to an oven is still on order. But I will make another post once I have a proper chance to reflow a board.Parts needed:Cheap toaster oven such asthis one.Arduino Uno or compatible.Type K thermocouple.Solid state relay with amperage ratings per your ovens requirements. The oven I have uses 10-11 amps under full load.Then just get your PCB flow groovin!(Edit: Forgot disclosure. I am in no way affiliated with Rocket Scream.)
Oven Temperature regulated RF detector diodes - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: October 02, 2025, 11:00:05 am
content: I just wanted to share something really cool and a bit crasy,inside an old instrumentKnott Elektronik WM 6001 WM 1001 Polyscanner 1200MHzI find metal blocks with drilled holes for the diodes, heater transistor temperature sensor opamp feedback,so the RF leves is constant and accurate, wow so much effort to make simple things accurate :-)if you like to see more about this look at 12:07in this video
Over current crowbar - Page 1
Forum section: electronics / projects

author: Phil1977
author_rank: Frequent Contributor
timestamp: May 14, 2024, 09:04:53 am
content: Hi together,please apologize if the idea was already discussed, but I couldn't find it using the search.Has anyone ever tried to build an overcurrent-crowbar with a SCR?I would like to have some protection device that prevents LEDs from getting destroyed when they are unintentionally connected to a live PSU with some output capacitance.So far I tried fast current limiters with MOSFETs, but I´m thinking if it could be done better by this circuit:|---|<---|(+) ------vvvv--------------------(+)L |PSU SCR Output|(-)-------------------------------(-)The inductance L is intended to limit the current gradient if the output is suddenly loaded. A trigger circuit watches the voltage over L and fires the SCR if it is too high. By rough estimations a small inductor of around 20uH delivers 1V at a current gradient of 50kA/s which would be clear indication of a dangerous load condition. A freewheel diode over L prevents voltage spikes at sudden load disconnection.The circuit needs no self-reset capability, it´s just a line of defense against LED damage.What do you think? Any ideas or comments before soldering it to a testboard?
Over Current Protection for Motor Driver(L298) - Page 1
Forum section: electronics / projects

author: kfc_n
author_rank: Contributor
timestamp: July 01, 2014, 12:18:42 am
content: Good Day!Need Help...Does anybody here has a schematic diagram for over current protection for L298 Motor Driver? I need to add it for my PCB component protection. I use L298 to drive stepper motor in my circuit...Thanks in Advance!

author: Psi
author_rank: Super Contributor
timestamp: July 01, 2014, 01:40:55 am
content: Looks like you use the current sense outputs of the chip to pull the enable line low at the current level you want to shutdown at.At a glance you'd need a comparator and a reference voltage to compare against.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 01, 2014, 03:34:13 am
content: Try a companion logic driver, like the L292. Or if that's a little too archaic, maybe just find something that's not the L298 to begin with..Tim

author: Kremmen
author_rank: Super Contributor
timestamp: July 01, 2014, 05:10:47 am
content: L292 is indeed an obsolete part and intended for driving DC motors. The OP has a stepper.The companion part of L298 is the sequencer L297. That one has a proper current sense/limit circuit in addition to the step sequencer. It allows you to tailor the details of the sensing circuit and also the current comparator reference is freely adjustable. This alows you to optimize the stepper so that during acceleration you can increase the current limit so as not to miss steps under heavier load. Once running steady you can lower the limit to nominal and when holding position, you can maybe decrease the current to let the motor cool down a bit. Always worked perfectly for me.The only drawback - if it is a drawback, that is - is that the sequencer only supports full and half stepping. For microstepping, you are out of luck. But in that case you can just steal the circuit from the datasheet and implement the current sense part with discrete logic and comparators.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 01, 2014, 11:30:05 am
content: Oops, I meant 297. Been a while since I played with that family!Tim