hybridfree/eevblog-posts huggingface dataset:
Rowenta 24V - Page 1
Forum section: electronics / beginners

author: Kerkana
author_rank: Contributor
timestamp: October 07, 2022, 09:36:00 pm
content: Hello,I have a problem with the RS-RH5313 board of my Rowenta Air Force 24v vacuum cleaner, I have the middle blue led flashing as if there was no more batteryI tested the battery which gives 24v, I also plugged the card into a 24v lab power supply, the led flashes, and in both cases I have 0v at the card output, the 24v arrives well up to at the switchNo short circuit since I put alcohol, and it only draws 0.009A when the led lights up, and 0.000 when it goes outSomeone would have any idea ?The card in question, the red corresponds to the input of the battery, the blue the output of the card and in orange I put where the 24v arrive on the switch in the off positionThanks
Royer Oscillator Capacitive Feedback  - Page 1
Forum section: electronics / beginners

author: eleccw
author_rank: Newbie
timestamp: November 21, 2021, 05:36:27 pm
content: Hello All, I’ve been looking at Royer Oscillators and I’m having difficultly in understanding exactly how the feedback works in the attached circuit.I understand basic operation of the standard Royer oscillator with extra feedback windings connected to the bases of the transistors. In the attached circuit, I know that the capacitors are used for feedback to the transistors instead of extra transformer windings.Could someone please explain to me step by step how the capacitor arrangement works in switching the transistors? I’ve learnt how the standard PNP astable multivibrator switches but I’m not sure how this capacitive divider works for the switching.In the astable multivibrator circuit, the RC combination determines oscillation frequency but I believe in this Royer circuit, the oscillation frequency is determined by the transformer magnetic flux and input voltage (this circuit oscillates at 2.5kHz). When the core becomes saturated, the EMF reverses and I believe it feeds back to the opposite transistor.I also don’t know if the capacitor network has any part in the frequency of this specific configuration. I’m not sure on the reasoning for the cap values if and the resistor values if they aren’t used for frequency.Any help would be greatly appreciated.
Royer oscillator instability - Page 1
Forum section: electronics / beginners

author: ezalys
author_rank: Frequent Contributor
timestamp: March 25, 2018, 04:46:19 am
content: Hey all! I've tried building jim williams' high voltage CCFL supply... well, a very basic version of it where I just short the bases of the transistors to ground (no regulation), ground one terminal of the secondary and load the other with a 200kohm resistor. Just to see how it works. To be clear, the only parts involved are the switch transistors, one 1k base resistor, one 200k resistor as a load on the secondary, tank capacitor, and the transformer. When I include the the tank capacitor, everything works very smoothly and happily. When I don't, the system seems to just oscillate chaotically. Measuring a terminal of the primary, I observe a series of decreasing spikes. It seems to be switching back and forth but without completely switching all the way, but also with varying period. Listening to the transformer, I hear a squealing noise that doesn't have a definite frequency. I'm a big fan of the resonant royer design but I'm curious what causes this behavior and how you alleviate it in a Royer oscillator that doesn't involve a tank capacitor to obtain a relatively clean square wave.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 25, 2018, 08:02:10 am
content: Sounds like squegging. You need a low enough resonant tank impedance to dominate over other possible modes of operation, and enough base bias to power it. You may or may not need/want base bypass capacitance (probably not; that's more relevant for single transistor (blocking oscillator) circuits), which causes squegging when the value is incorrect (again, a value of 0 might be most correct here).Don't at all expect it to behave like a fixed mains supply. The whole point of the oscillator is that you're sacrificing ease of use for sparsity of components. Expect quirks!Tim
Royer/Mazzilli oscilator theoretical operation - Page 1
Forum section: electronics / beginners

author: drdm
author_rank: Contributor
timestamp: January 11, 2020, 01:28:09 pm
content: Hello everybody,I have to build a power supply that needs to be powered by a battery and provide about 1500V with output current in the micro ampere range. It is for an university assignment, so I have to provide proper calculations and documentation with it. the PS is composed of a Buck converter that feeds Royer/Mazzilli oscillator which in turn powers a Cockroft-Walton multiplier. Output voltage is to be taken from the output and used to regulate the Buck (still no idea how to do that, but we'll get there). For weeks I've been browsing the internet and some books and I can not find a proper theoretical explanation on the Royer/Mazzili oscillator. How do you choose the right components? How do you calculate currents and voltages? How do you calculate the impact of the load? How do you regulate the output voltage?I know the the difference between Royer and Mazzilli is the way the Switching components are driven, so I am using a Mazzilli oscillator, but I find that they are quite similar.I have attached the schematic I am using. It's based on a simulation that I found in this forum. So here are my questions (there are a lot):1. L1 is 2mH while transformer windings are 1uH each. L1 is supposed to keep the input current smooth, but why does the oscillator need constant input current? How do I calculate (or at least justify) that 2mH (why not 1mH or 3mH)? Also how do I calculate the peak current of L1?2. How do I find the peak voltage in points A and B with respect to GND? In one source I found out that that it is the input voltage times 3.14(pie), but why?3. How is the current trough Q1 and Q2 calculated? In the simulation it is constant during the ON period, I am guessing due to L1.4. How does V_OUT depend on R_LOAD and V_IN?5. Can I model the Load resistance to be in parallel with C1?6. I red that the circuit oscillates with the resonant frequency of C1 and the transformer primary winding (FG). Is that true, because the simulation shows a different result?7. Can I somehow calculate the peak currents trough the transformer?I hope the topic is not too wide and is posted in the right section. Thank you n advance to anyone who is willing to help?Best regards!

author: magic
author_rank: Super Contributor
timestamp: January 11, 2020, 03:45:48 pm
content: Seems rather complex for a job that a simple one stage flyback could do.Getting or making the transformer would be the only tricky part as your voltage is above laptop CCFLs as far as I know but below automotive or CRT flybacks on the other hand.

author: drdm
author_rank: Contributor
timestamp: January 11, 2020, 04:29:37 pm
content: I agree that it is complex, but what can you do? It's an assignment. The Cockroft-Walton is necessary due to the type of load, but that oscillator caught me off guard.
RP2040 / ESP12-F server - Page 1
Forum section: electronics / beginners

author: JoshuaToast
author_rank: Newbie
timestamp: June 02, 2025, 03:13:10 pm
content: Hi everyone! I'm still quite new to electronics, and this is by far the most complex project I’ve attempted so far. The idea is to build a simple server system entirely from scratch using an RP2040 microcontroller and an ESP-12F WiFi module. The system will be powered through a USB-C port, which should also handle charging a LiPo battery. When the USB-C is connected, the system should draw power from it directly and charge the battery at the same time. When USB-C is unplugged, the battery should automatically take over as the power source.The RP2040 will handle the main logic, and the ESP-12F will manage the wireless connectivity. I’m using the IP5306 power management chip to manage charging and power path switching. According to the datasheet, it supports simultaneous charging and discharging, so in theory it should do what I need(?)I've been reading a lot of datasheets and documentation, but some parts are still unclear to me, especially around power path behavior, proper sequencing, and ensuring safe operation for both the microcontroller and WiFi module. I'm probably missing something or getting things wrong, so I’d really appreciate any advice or guidance from more experienced folks.Thanks in advance!

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: June 02, 2025, 03:16:52 pm
content: Have you made a prototype and tested it yet?

author: JoshuaToast
author_rank: Newbie
timestamp: June 02, 2025, 03:32:20 pm
content: Hi, no, unfortunately I wasn't able to get the separate components to test it.

author: ataradov
author_rank: Super Contributor
timestamp: June 02, 2025, 07:20:24 pm
content: Is this the final schematic? It is missing a bunch of stuff. You need the flash for the RP2040 firmware. You need a crystal. You also need 5.1 kOhm resistors on CCx pins. D+/D- pins on the connector need to be pairwise connected. Yor DVDD pins are not connected. You don't have any bypass capacitors.Take reference schematics for all the used parts and at least check against those.

author: xvr
author_rank: Frequent Contributor
timestamp: June 03, 2025, 05:46:43 pm
content: Just curious - why RP2040+ESP12 instead of single ESP32 module? It also already includes all needed circuits which you have to add to get RP2040 working.
RPi controlled MOSFET for high current load - Trying to understand - Page 1
Forum section: electronics / beginners

author: elcrni
author_rank: Regular Contributor
timestamp: December 21, 2021, 11:12:02 am
content: hi everyone,So for my next project i would need to have two switches controlled by RPi 4b GPIO pins. Since RPi pins are 3.3v and max current of 16mA, i have been researching viable solutions for a few days now.There are plenty cheap MOSFET modules (Amazon, eBay...Ali) but i would really like to understand what i am using and how to properly use it, rather then just hook it up. I've learned so far that just because MOSFET seems to "work" that doesnt mean it works as it should and that the circuit is well designed for the purpose and safe.So, first what i need:1. I need a switch that would toggle 12V AC relay ON/OFF.I am using FINDER 48.62 relays, specs attached. It should draw some cca 100mA of current, i have figured i could use 2n2222 transistor for this, as shown on the schematic below:Is this OK?Screenshot 2021-12-21 114303.pngScreenshot 2021-12-21 114125.png2. I need a switch to control LED strip, cca 3A - 4A of current.For this i have found many possible solutions but honestly i do not like any of them. Some claim to work straight from RPi 3.3V GPIO, some dont claim anything, some would work on 5V signal.I could use low level trigger relay module with optocoupler, straight from RPi GPIO but i would prefer silent/no click solution, thus MOSFET is a perfect choice.As already said, some MOSFET modules claim to support 3.3V signal and yes, they do "work" with 3.3V but as soon as i want to draw more than 1-2A of current they get hot, indicating they do not fully open and conduct, so some sort of level shifting to 5V has to be implemented.a) this solution includes ready made solutions like attached modules:For this one, i should still use NPN/PNP transistors like in "b" solution from below, to shift to 5V...61yu2ts7xtS._SL1000_.jpg71241-KcfEL._SL1500_.jpgb) this would be preferred solution and i can easily implement this, or even quickly design a PCB that would be reliable and have properly designed circuit. In this case i am using external 5V source, not the RPi 5V pinThe questions here is, how come there are no ready made modules featuring below schematic design, if that is a proper way to do it?Image courtesy ofhttps://quadmeup.com/raspberry-pi-mosfet-high-power-switch/Hi-power-switch_schem.pngMany thanks for any help in advance,Alek

author: Terry Bites
author_rank: Super Contributor
timestamp: December 21, 2021, 12:23:11 pm
content: Just use the same type mosfet for both switches eg a DMG9926 or FDS9926A dual.

author: elcrni
author_rank: Regular Contributor
timestamp: December 21, 2021, 12:52:09 pm
content: Quote from: Terry Bites on December 21, 2021, 12:23:11 pmThanks!I have IRLML6344TRPbF on hand, so i may use two of these directly on 3.3v GPIO, just looking at the datasheet:https://asset.conrad.com/media10/add/160267/c1/-/en/000161191DS01/datenblatt-161191-infineon-technologies-irlml6344trpbf-mosfet-1-n-kanal-13-w-sot-23.pdf
RPM effect on output of 3phase AC dynamo - Page 1
Forum section: electronics / beginners

author: newtothis
author_rank: Contributor
timestamp: January 29, 2015, 08:43:14 pm
content: Hello everybody,Google failed me so I hope you would kindly help me.I recently made a spontaneous bid on an low bid auction on ebay and suprisingly won a three phase AC dynamo/motor for Next to nothing.The dynamo comes with 6 diodes so a rectifier for DC can be made. I think I will add a capacitor also to smoothe out the ripples.The question is simply what happens at different RPMs Applied at the primary gear?My Google was less than succesfull and the only info I could find is that lowering of RPM causes hertz to be lowered and vice versa, but how will this affect the voltage / current in theDCoutput - I got the impression that voltage is unaffected, but then current must be changed, I mean something has to give?In addition the dynamo is listed as 3V-5V contradicting my earlier impression.I would really like to know it because I want it to have a purpose and I have considered make a windmill or watermill and harness the output for something.. a small fountain, lamp.. not really sure yet - but I need to know the output first.Link to an identical item:(http://www.ebay.com/itm/DC-3V-5V-Hand-cranked-Dynamo-Charger-Flashlight-Generator-Brushless-Gear-Motor-/181418530418?pt=Radio_Control_Parts_Accessories&hash=item2a3d631672)Thank you

author: IconicPCB
author_rank: Super Contributor
timestamp: January 29, 2015, 10:13:59 pm
content: Both frequencyand voltage will be affected. Voltage will drop with reduction in RPM assuming no active regulator present.If the regulator is present then the voltage versus RPM will be under the control of regulator.

author: ovnr
author_rank: Frequent Contributor
timestamp: January 29, 2015, 10:19:02 pm
content: First off, that's... not really a dynamo. It's just a cheap 3-phase BLDC motor, and like almost all motors it can work as a dynamo.The output voltage, current and frequency will change depending on RPM. It cannot be directly regulated via adjusting the field strength, like proper dynamos, so if you require a constant voltage, I suggest a buck-boost regulator on the rectified output.Also, it's probably crap. Good luck, tho!
RS-485 to Arduino Circuit - Page 1
Forum section: electronics / beginners

author: scott216
author_rank: Regular Contributor
timestamp: October 08, 2014, 01:00:10 pm
content: I have a R.M. Young weather station that outputs data via RS-485. I want to capture this data with an Arduino. So I got aMAX485 chipand hooked up this circuit:Except pins 2&3 don't go to D3, they go to ground via a 10k resistor. R1 = 120 ohms. I'm communicating at 9600 baud. The communication only needs to be one-way: from weather station to Arduino. My Arduino will only be a couple inches from the weather station console, so the RS-485 signal is not traveling far at all.I wired this up and it works great. I want my setup to be very reliable since data from the weather station will signal an alarm under certain conditions. Is there anything I should do to make this circuit more robust?

author: abaxas
author_rank: Regular Contributor
timestamp: October 08, 2014, 01:05:53 pm
content: Just go to ebay/aliexpress and buy a serial to rs485 convertor doodar.£1.64 on aliexpress delivered.

author: scott216
author_rank: Regular Contributor
timestamp: October 08, 2014, 01:49:32 pm
content: Quote from: abaxas on October 08, 2014, 01:05:53 pmI want to make my own PCB, I have a few other things I need it to do.

author: David_AVD
author_rank: Super Contributor
timestamp: October 08, 2014, 09:23:33 pm
content: You can just tie MAX485 pins 2 and 3 to 0V. No real need to the resistor unless you want to leave the option to make it bidirectional comms in the future.Add a 100n bypass cap from MAX485 pin 8 to 0V.

author: scott216
author_rank: Regular Contributor
timestamp: October 09, 2014, 02:37:58 pm
content: Quote from: David_AVD on October 08, 2014, 09:23:33 pmThanks. I used a resistor only because I found a schematic online that had it. It's nice to know I don't need it.
RS 485 Voltage Levels / bias network - Page 1
Forum section: electronics / beginners

author: gogoman
author_rank: Regular Contributor
timestamp: July 26, 2018, 12:24:55 pm
content: Hi the RS485 i'm looking at does not use a bias network, when the BUS is idle the differentials (A/B) have the identical voltage levels.is this normal?The RS232 is converted to RS485, when the bus is idle the signals A and B are at 0v and 5v.the voltages swing rail to rail, I was expecting the signals to be ~1/2 of VCC(5v) with a different of 200mv.Is this a exceptionable?In both cases the bus has a single driver and multiple receiversthanks

author: mrkev
author_rank: Regular Contributor
timestamp: July 26, 2018, 02:26:57 pm
content: Yes, this is "normal". The RS485 driver has two diferencial outputs that go from 0 to 5 volts. Reciever on the other hand has to be able to opperate with 200mV difference. This way, you can make even very long bus work - f.e. 3km line of UTP is still ok.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 27, 2018, 12:50:20 pm
content: If an RS485 wire pair is not driven because all nodes are in "receive" mode then the termination resistors will pull the wires to each other.In this case noise picked up by long wires can easily be more than the threshold and the RS485 receivers may receive false data.This is why there is normally a bias network on the wires.Any RS485 network in which the direction is switched over a single wire pair should have these bias resistors.RS485 should also have a 3rd GND wire to make sure the common mode voltage does not esceed the limits of -7V to +12V on the signal lines."10 ways to bullet proof RS485" is an (old) National Semiconductor AN and well worth reading.https://duckduckgo.com/html?q=10+ways+to+bullet+proof+RS485Note:A RS485 driver should be able to get reliable data from a 200mV signal, but it could be triggered by a much lower signal. I would not be surpized if a 50mV noise spike generates a false bit.
RS Components order vanished - Page 1
Forum section: electronics / beginners

author: Nogtail
author_rank: Regular Contributor
timestamp: November 28, 2016, 01:45:22 am
content: I recently placed an order with RS Components (AU) as it was a small order and they had free shipping. I have received a confirmation email but the order is not showing on my account page and support say they have no record of the order so they cannot help.Is this a common occurrence at RS?Are there any other distributors in Australia who offer free shipping on small orders?

author: Marinated
author_rank: Contributor
timestamp: November 28, 2016, 04:08:05 am
content: Have you confirmed that the payment went through? I have only once had a similar problem with RS. Don't let their customer service get away with their treatment of you, produce the order confirmation and demand action. They are mindless drones trying to get rid of you. Escalate the situation if necessary.

author: Brumby
author_rank: Unknown
timestamp: November 28, 2016, 04:45:32 am
content: I've only ever bought from RS over the counter - they're too close to worry about shipping.

author: Nogtail
author_rank: Regular Contributor
timestamp: November 28, 2016, 05:06:07 am
content: Quote from: Marinated on November 28, 2016, 04:08:05 amI'm not sure if the payment went through yet, it often takes a few days to show in my bank. I have been told by customer support that the order "has been archived for some reason" and that I will need to place the order again. I will update this if anything strange happens.

author: BradC
author_rank: Super Contributor
timestamp: November 28, 2016, 12:16:37 pm
content: I use them all the time. I try and keep the orders to a reasonable size, but sometimes you just need $0.20 worth of resistors tomorrow. They've always come through if the web page said they were in stock for next day delivery. I've had the odd issue with Toll not knowing what "express" meant, but RS always shipped when they said they would.

author: Nogtail
author_rank: Regular Contributor
timestamp: November 29, 2016, 02:38:32 am
content: My order finally decided to show up over 2 days later (after part of it had already arrived) so thankfully I decided to wait before placing the order again.For some reason it is being displayed as 3 separate transactions in my bank that total to around 8% extra than the price displayed when I ordered. This could quite possibly be some sort of money transfer fee but it seems a bit strange.

author: BradC
author_rank: Super Contributor
timestamp: November 29, 2016, 10:31:51 am
content: If they don't have everything in the one place it's common for orders to be split and shipped separately, they will also only charge you for the stuff that has shipped. I've never noticed a surcharge however, but to be honest I don't look all that closely. I'll keep an eye out in future.
R&S SMA 100 A shutting down - Page 1
Forum section: electronics / beginners

author: hinxx
author_rank: Contributor
timestamp: April 08, 2024, 08:51:00 am
content: My SMA 100 A started behaving weird lately. It powers on and then after a couple of minutes it powers itself off. The log is full of errors about how it can not write to EEPROM with no other errors reported.I've opened up the box and noticed that all the heatsinks are of funky, in a charred like color. Here are some pics. It looks like dust was "baked" onto the heatsinks. Quick inspection shows that no components / cables / wires seem to be damaged. Any ideas on what happened?After the device powers off (yellow) light near the frontpanel power on button lights up I can't get it to power on unless I turn the main power switch off and on again.I do not feel any excessive heat on the heatsinks, and the fan is spinning.I guess I could replace the EEPROM but I'm thinking that failing to write data to it should not be a reason for shutdowns..

author: m k
author_rank: Super Contributor
timestamp: April 10, 2024, 07:50:49 pm
content: Maybe EEPROM has a write enable from behind something that is not ok.Heatsinks should be heated, possibly quite a bit.It's also possible that normal temperature is much more than what can be touched.But intuition says it's different here, don't trust intuition.There can also be a temp sensor that is past its last day.
RS232 Testing - Page 1
Forum section: electronics / beginners

author: Spark-Doctor
author_rank: Contributor
timestamp: December 01, 2019, 10:38:20 am
content: Hi AllI am trying to get to grips with RS232 communications. Could anyone tell me the easiest way to set up a test with a Rigol DS1054Z so i can see the signals.many thanksIan

author: ebclr
author_rank: Super Contributor
timestamp: December 01, 2019, 05:18:52 pm
content: Set voltage to 2V / Div and use a probe on X10 mode ( RS232 can go +12 -12 in the worst cade scenario ) Just connect one probe on RX and GND, another probe on TX and GND, adjust the time base according to the baud rate , supposing some communication is happening between your devices, you will see one signal for tx and another for RX. If you have the decoder option enabled, you can even see in data format

author: SL4P
author_rank: Super Contributor
timestamp: December 01, 2019, 05:46:48 pm
content: There’s not much to ‘see’ other than an idle signal with bursts of ‘data.’ shaking the lines as they are transmitted.Keep in mind that across each ‘byte’ transferred, you’ll see a start bit, followed by the data bits, an finally the optional parity and stop bits.If the data is ‘slow’ enough, you can count off the bits, and decode the byte value in your head ... that gets boring very quickly- or use a protocol decoder to make it easier.

author: Electro Fan
author_rank: Super Contributor
timestamp: December 02, 2019, 03:33:08 am
content: Connect a probe as ebclr described to the TX and GND pins on a RS232 port on a PC. Set the controls as per page 7-7 in the Rigol 1054 manual to decode the data. Try using both ASCII and binary settings. On ASCII you will see the Byte characters - try adjusting the time base to get the characters to fit neatly in the green decoder boxes. On binary you will effectively see 1s and 0s*; look for an ASCII table on the Internet and you will get a sense of how the bit (binary digit) patterns represent the Byte characters. The ASCII encoding plus the asynchronous timing (start and stop) bits, plus the parity bit all turned “on and off” (high and low) as reflected by the amplitude (~ +/- 12 Volts) in a serial stream at the specified baud/bit rate will help you visualize RS-232 in operation.*Toggle the 1s and 0s, effectively the on and off or in this case the high and low states by using the control for the negative logic (the convention) for RS-232 using 0 as high and 1 as low to see the impact on the decodes; likewise try toggling the between the Least Significant Bit and the Most Significant Bit to see the impact on the decodes. Keeping a copy of the ASCII table will help (but technically the RS-232 spec is an electrical (and mechanical) spec that focuses on signaling and timing - which is separate from the ASCII standard.)
RS232 to Ethernetmodule - Page 1
Forum section: electronics / beginners

author: alamwte
author_rank: Regular Contributor
timestamp: April 18, 2021, 10:38:14 am
content: HiI have a module that convert RS232 to Ethernet.Now I have some questions. I can not recognize which connector is for input power?And where is RS232 port on this module?Please guide me.I attach the photo and datasheet below.

author: mariush
author_rank: Super Contributor
timestamp: April 18, 2021, 12:59:04 pm
content: See page 23 and onwards in manual.My best guess is that the 3 pin header on the right side is the rs232 .. the text seems to say V+ , TX and RXThe 4 pin header is probably the input for the MAX232 chip .. see page 24, the TXD0, RTS, RXD0, and CTS pins ... these are expected to be -12v ...0 level voltages... I think. The 3 pin header is ttl level signals, 3.3v or 5v? see manual.the 5 contact edge connector ... well, first contact looks to me like 5v or some input voltage, as it goes through a diode (probably reverse voltage protection) and then a capacitor and seems to power the max232 chip.I'd look on the back side for the ground contact pad, if the edge connector is double sided.2nd contact .. no idea, but trace seems too thin to be ground ... so I would guess it's an enable/sleep pin for the max232 chip or maybe some option to not do voltage level conversion3rd contact seems unused and 4th and 5th are shorted together, i suspect it's a sort of key/detection mechanism for the device the card is supposed to be plugged in (for that device to determine there's something installed in the slot)Don't have a picture of the back side so no idea if there's contacts there or not.edit : the green stuff by the ethernet connector ... if those are dip switches , see page 26, seems like low speed/high speed mode setting by adjusting two switches.

author: alamwte
author_rank: Regular Contributor
timestamp: April 19, 2021, 03:59:46 am
content: Thank you very much
RS232/CAN interface for 2002 Volvo s60? - Page 1
Forum section: electronics / beginners

author: zerorisers
author_rank: Regular Contributor
timestamp: September 04, 2015, 04:46:08 pm
content: Hey guys. I have been looking around and thought somebody here might have an idea of what I should do. Im looking for a way to hook into the CAN network on the VOLVO s60 using the rs232 COM port on my computer. Would anybody here have an idea on how to do that and whatever chips are needed I wish to get from TI as I have some contacts in there that can get me what I need.

author: marshallh
author_rank: Unknown
timestamp: September 04, 2015, 08:46:00 pm
content: Buy a clone DiCE OBD dongle, save yourself the trouble. Or if you really want to go off the deep end, use an ELM can/obd interface chip.

author: R_G_B_
author_rank: Frequent Contributor
timestamp: September 06, 2015, 08:20:20 am
content: You could try getting one of these from eBay.http://www.cananalyser.co.uk/R_G_B
RS232/Serial Port to Button - Page 1
Forum section: electronics / beginners

author: gifter
author_rank: Newbie
timestamp: September 29, 2014, 07:57:47 am
content: hello guys im still a newbie and wants to learn basic electronic skills.would like to build my own DIY serial port to button that needs to be compatible with my modem..i have tried resources from web on how to, but sad to say im still not able to meet my goal..

author: fcb
author_rank: Super Contributor
timestamp: September 29, 2014, 10:03:46 am
content: You'll more than likely need a microcontroller to do this, and the 'goto' solution for a newbie is likely the arduino (so start with the arduino forums).

author: ZTE
author_rank: Newbie
timestamp: September 29, 2014, 08:13:35 pm
content: If you're asking about creating an input from your serial port this is entirely possible, You can run a wire from the RTS pin through a switch and into the CTS pin then set the RTS pin high and when the button is pushed the CTS pin will go high, I actually use something like this in one of my projects. Just ask if this is what you're trying to do and want some more info.
RS422 Signal Measurement Issue: Seeing Two Identical Signals - Page 1
Forum section: electronics / beginners

author: Abdeldjafer
author_rank: Newbie
timestamp: September 25, 2025, 04:38:39 pm
content: Hello everyone,I'm currently trying to measure an RS422 signal and im running into an issue with my oscilloscope readings. My setup involves a device that normally communicates via a DB9 connector, which carries multiple RS422 signals. For my measurement, I've manually pulled out the two wires for a specific signal pair (TX+ and TX-) and im using my scope probes directly on them. I am using two separate channels to measure the signals without connecting the ground clips to anything.The problem is that instead of seeing two waveforms that are 180 degrees out of phase, which is what I would expect from a differential signal, the two waveforms appear to be almost identical. They rise and fall at the same time and show no phase difference.What causes this issue?

author: eugene
author_rank: Frequent Contributor
timestamp: September 25, 2025, 04:42:07 pm
content: If the signal you see looks more sinusoidal than digital, then it's probably common mode from the lights, power lines, etc. Connect both ground clips to ground.
Rs485 Modbus Protocol - Page 1
Forum section: electronics / beginners

author: rmrps
author_rank: Newbie
timestamp: October 25, 2018, 10:48:34 am
content: Hi FriendsI am new to rs485 communication i want to know how to create rs485 modbus protocol using given register value for accessing information that is read data and write data i have baud rate is 115200 data is 7, parity even stop bit is 1 and register address isfor reading data register address is D174for write data register address is M605 and M72slave id is 3APlease guide me to create Rs485 Modbus protocol using the above register value

author: hsn93
author_rank: Regular Contributor
timestamp: October 25, 2018, 12:16:29 pm
content: http://www.simplymodbus.ca/FAQ.htmhttps://github.com/4-20ma/ModbusMaster/blob/master/examples/Basic/Basic.pdegood luck.

author: MiDi
author_rank: Frequent Contributor
timestamp: October 25, 2018, 12:55:59 pm
content: Official Modbus specsIt is not as trivial as a simple protocol, it is rather complex.Search if you get a library for your programming language, you will find at least one for the popular ones.
RT5350 how much flash memory does it supports? - Page 1
Forum section: electronics / beginners

author: u666sa
author_rank: Frequent Contributor
timestamp: November 22, 2023, 05:46:36 pm
content: Let's say my router has 25q32bvsig, that's 4 megabytes of flash. I know for sure I can install 25q64bvsig, it's been done, which should get me 8 megabytes of flash. Question is, can I install more? 128 megabit, or 256 megabit?I went up and down datasheet and didn't find any specification.
rtc xtal - Page 1
Forum section: electronics / beginners

author: m3vuv
author_rank: Super Contributor
timestamp: March 12, 2022, 08:53:06 am
content: Hi all,I have a Kenwood dsc-8200 dso,a few years ago it stopped keeping its timeThe rtc timekeeper ic is an OKI m6242B ic,there is no schematic for the scope so downloaded and refered to the datasheet to locate the components for the rtc oscillatorie 2x 22pf caps a couple of diodes and a 32.768 xtal,i replaced those and also the backup battery,it worked for a couple of years then started loosing the time againe,i assumed the backup battery was flat ,changing it didnt cure it!.I have just replaced the xtal and its working fine againe,is there a reason for the xtal to have failed?.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 12, 2022, 09:52:43 am
content: Have you considered whether that crystal is being overdriven?https://www.nxp.com/docs/en/application-note/AN3208.pdf

author: m3vuv
author_rank: Super Contributor
timestamp: March 12, 2022, 09:58:34 am
content: Its driven directly from the ic so doubt its overdriven,see pic.

author: m3vuv
author_rank: Super Contributor
timestamp: March 12, 2022, 10:05:25 am
content: The xtal i replaced it with was from an old pc motherboard,same DT-38 case style but unknown frequency!,maybe i got lucky as it seems ok! lol.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 12, 2022, 10:06:35 am
content: You have a choice in the capacitors to use. What did the datasheet for your crystal recommend? Some recommend considerably less capacitance.

author: CaptDon
author_rank: Super Contributor
timestamp: March 12, 2022, 02:16:04 pm
content: I have found over the years that some of those RTC crystals apparently had very poor hermetic seals and when carefully disassembled showed the silver plating on the crystal to be heavily tarnished with evidence of silver migration. That stops 'em dead in their tracks!! I found the same thing happening to the channel frequency control crystals on mobile and maritime radios back when each channel had a crystal. The complaint was "They say my radio sounds distorted" and sure enough the transmitter was off frequency by a good bit. Didn't seem to effect the receiver frequency as much?

author: m3vuv
author_rank: Super Contributor
timestamp: March 12, 2022, 09:24:54 pm
content: I used kemet ceramic caps,both measured at 27pf,guess age killed the xtal then?.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 12, 2022, 09:38:06 pm
content: Seems logical. Get a new crystal with datasheet. Install as indicated by its DS. Considering the age of the device, I would get a "standard" size crystal, not a tuning fork the size of a pencil lead.

author: Benta
author_rank: Super Contributor
timestamp: March 12, 2022, 10:14:31 pm
content: Quote from: m3vuv on March 12, 2022, 09:24:54 pmAge perhaps, more likely a mechanical impact. The 32 kHz "tuning fork" crystals are sensitive.27 pF is a bit high, 15...22 pF should be ball park. But you'll see it if your clock runs slow.Note that there are two flavours of 32 kHz crystals with either 8 pF or 12 pF load capacitance.
RTD2660 generic display controller board - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: May 29, 2025, 05:30:57 pm
content: I'm posting here so may be some else came across this kind of issueI bought these two boards and screens (7 in) about 7 years ago. at that time I tested all working good and put them for later any use.I powered them on today but one controller is totally dead (do display) and other shows screen power on video source AV1, I have connected an AV source to board but no displayIf I use controller key pad to change video source screen goes off, only power button works as expected, remote does not respond.I wanted to know if anyone else came across this kind of issue? these boards where sitting in original packingAny idea if/how can I troubleshoot them?

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: May 31, 2025, 12:09:32 pm
content: Use a multimeter to verify the voltage at the input to the board (usually 12V). Inspect for cold solder joints around the power connector.

author: sairfan1
author_rank: Frequent Contributor
timestamp: June 02, 2025, 07:05:03 pm
content: It powers up properly but no response.

author: darkspr1te
author_rank: Frequent Contributor
timestamp: June 03, 2025, 08:17:08 am
content: it might be worth seeing if you can can to the i2c side of the chip, there are various firmware out there for these boards that alter it's behavior a lot. but the basics is if you can talk on i2c then there a issue with the chip.darkspr1te
RTL8201CP PHY interface not working - Page 1
Forum section: electronics / beginners

author: alegioit
author_rank: Newbie
timestamp: August 26, 2019, 04:01:07 pm
content: Hi all,this is my first topic. Please do not be mad if I use wrong terms or at my poor English grammar (I'm Italian).This is my first tinkering with PHY interfaces and as usual, at the first try (for me), nothing worksMy goal is to have a microcontroller (stm32f429vgt6) that receives TCP or UDP packets and then do something on its gpio or its other communication buses. To do that I wanted to link the microcontroller with a PHY transceiver (RTL8201CP) using the MII interface.Long story short I've created the PCB hereby attached, but when I connect the ethernet cable from my switch nothing happens (no link led is lit on the switch or on my circuit): I've already checked with my oscope if something is passing through the link and I see that there are bursts on the RX line of the circuit (so the switch is actively trying to communicate).I've already checked all the connections and everything seems fine (but if you have a clue that there is a fault connection I'll double-check it!). The RTL8201 is working: when the NRST line is low the chip resets (LEDs turn on briefly) and if I test the 25MHz crystal it resonates correctly.I think that the problem is located in the connections between the RTL8201 and the ethernet connector (see the attached schematics): I've tried to find a suggested schematic on the Realtek website, but I didn't find any! (if someone has it and he will send it to me I'll appreciate a lot!). So I used the schematic that I've found on the internet, but they differ a lot!In particular, some of them connect the centre tap of the magnetics that runs to the IC to a decoupled VDD (as I've done), others connect them to GND using a 100nF capacitor and others connect the magnetics directly to the RTL8201 (who is right? I think it depends on the PHY interface ICs, but I can't find anything about it on the RTL8201CP datasheet...). The same happens for the other side of the magnetics (from the magnetics to the rj45 connector): some of them includes the 75ohm resistor others don't...I am pretty sure that the problem is there because when I was trying to inspect the circuit with my oscope (i had previously removed the 50ohm resistor to see if something was changing) and I connected my oscope probes to the TPTX terminals of the magnetics the collision led started to blink and after trying a couples of times (reset, touch the terminals, reset, touch, etc...) I was able to establish a link (the link led on my circuit was on and so the one on the switch).I think that all my problem depends on the poor designed PCB, but this is my first try on designing something so em sensitive...Could you help me in finding the cause (If you need that I do other checking/measurements please ask and I'll do them asap), correct my errors, give me an advice (if you have some documentation about the problem I'll be more than glad to read it!) and maybe help me in correcting my PCB and schematics?Thanks a lot!PS: I've zipped all the schematics together to upload and download them easily!
RTL8370N datasheet - Page 1
Forum section: electronics / beginners

author: alamwte
author_rank: Regular Contributor
timestamp: January 06, 2021, 11:28:34 am
content: Hello,I am looking for RTL8370N datasheet but I can not download it in any site.Would you send me this datasheet if you find it, please?Thank you

author: DC1MC
author_rank: Super Contributor
timestamp: January 06, 2021, 03:06:30 pm
content: You can get it here:https://github.com/libc0607/Realtek_switch_hacking/blob/files/RTL8370(M).pdfand here's a GitHub repository with things that may interest you:https://github.com/libc0607/Realtek_switch_hackingCheers,DC1MC

author: alamwte
author_rank: Regular Contributor
timestamp: January 06, 2021, 06:19:42 pm
content: Thank you so much dear DC1MC
RTO  basics - Page 1
Forum section: electronics / beginners

author: gogoman
author_rank: Regular Contributor
timestamp: March 07, 2019, 12:49:59 pm
content: Hi when a RTOS is paused and the system tick timer is set to 20ms, my understanding is the task remains idle for 20ms.What happens if a interrupt occurs or other task need to be service in this 20ms window, are they ignoredI'm new to this subject so take it easy.thanks

author: mikerj
author_rank: Super Contributor
timestamp: March 08, 2019, 12:24:57 pm
content: Do you mean a Task is in a blocked state (e.g. it's waiting for a system delay to end or on a mutex/semaphore to become available) rather than the entire RTOS scheduler being suspended? If so then the the RTOS will immediately switch to highest priority task in the Ready state if one is available.If the RTOS waited around until the end of the ticker tick interval it would waste lots of CPU time. The timer tick will preempt a task if a higher priority task is ready.

author: rstofer
author_rank: Super Contributor
timestamp: March 09, 2019, 05:41:06 pm
content: Hardware interrupts cause hardware action regardless of the state of the scheduler. So, the system will vector to the interrupt handler. What happens after that is a matter of code. It could be a device like a USART and the vector is for data received. The interrupt service routine will grab the character, probably put it in a circular buffer (queue) and set a semaphore. When the interrupt handler is done, it will notify the scheduler to potentially switch contexts depending, of course, on priority. It could be that some task is waiting on the semaphore for data available and, again, depending on priority, that task will get dispatched. At the least, it is on the pending list.The scheduler tick is usually around 1 ms not 20.FreeRTOS has a lot of documentation and is pretty much the standard in the industry at this point:https://www.freertos.org/Documentation/RTOS_book.htmlMANY development boards/tools (STM, PSOC, etc) come with FreeRTOS examples.
RTOS for beginners - Page 1
Forum section: electronics / beginners

author: rakeshm55
author_rank: Regular Contributor
timestamp: May 10, 2017, 10:45:57 am
content: Recently I tried Ti-RTOS online training videos....https://training.ti.com/ti-rtos-workshop-series-1-10-welcome....I have tried their labs too....Is there any online literature available for a beginner to gain entry to the world of RTOS??... I have very limited embedded experience...

author: Kjelt
author_rank: Super Contributor
timestamp: May 10, 2017, 11:33:55 am
content: Try to find theUsing the FreeRTOS Real Time Kernel - Standard Edition 2010by Richard BarryIf i remember correctly you can find some free pdf for a specific processor (sponsored) online.Ah here they are:www.freertos.org/Documentation/

author: ^_^
author_rank: Regular Contributor
timestamp: May 10, 2017, 12:36:04 pm
content: ThreadX in Renesas Synergy is click-and-configure type of RTOS.It's easy to start if you want real world experience.They have an online PDF describing it.For more in-depth thing I'd suggest microC - a book about uC RTOS.It describes RTOS operation itself in detail. If you know C then it's not a problem.There was also an RTOS that won (?) 1kb hackaday challange not so long ago, you can check it out, very simplfied, great to start.

author: tggzzz
author_rank: Super Contributor
timestamp: May 10, 2017, 01:20:47 pm
content: Most RTOSs offer very similar functionality; learn one and it is easy to transfer the experience to another.What is far more interesting is learning how to structure your design to ensure the operation is predictable, reliable, and easy to change as new requirements are uncovered. With hard realtime systems there are a whole class of problems (e.g. priority inversion, interrupts) that are completely unfamiliar to traditional software writers, but which will occur infrequently at the worst possible moment.If you want to learn how to structure your thinking and design so as to avoid such problems, then take a look at the XMOS products. They have significant advantages such as a sound theoretical pedigree (CSP), cheap many core processors, FPGA-like i/o speeds, and a development environment thatguaranteesworst-case performance timingwithoutexecuting the code. The starter kit costs only £12, and apure softwareimplementation can be a >10MHz frequency counter with 2 or more input channels.Even if you don't use their products, you can use the design styles to improve your designs using conventional architectures.
RTS and CTS UART pins - Page 1
Forum section: electronics / beginners

author: Silenus
author_rank: Contributor
timestamp: January 13, 2015, 02:53:46 am
content: Hey guys, I am looking to put aWiFlyinto an embedded board that I'm making. In the datasheet, it says the most basic setup uses the PWR RX TX GND, however in the diagrams the UART is utilising the additional CTS and RTS pins. Do I need to connect these pins for serial comms to work between the module and MCU?

author: apelly
author_rank: Unknown
timestamp: January 13, 2015, 03:09:15 am
content: RTS & CTS are for hardware handshaking. With only RX, TX & GND you can do software, XON/XOFF handshaking.I haven't looked but you'll probably find that the WiFly is configurable for either. I don't think much uses hardware handshaking anymore, but I am prepared to be corrected.

author: digsys
author_rank: Unknown
timestamp: January 13, 2015, 03:37:33 am
content: agreed. Worst case, you tie RTS or CTS High (whichever is designated as Input to the WiFi module). ie always on.
RTU5024 not connecting to network - Page 1
Forum section: electronics / beginners

author: Gert
author_rank: Newbie
timestamp: August 15, 2023, 11:17:03 am
content: Dear Sirs , I have changed the SIM card between 3 service providers respectively. Checked the area signal which is good. Removed alk SMS messages from sims also passwords removed. Checked and changed antennas., Alos tested the unit within a 50 meter radius of one similar one that is working fine. The Rtu stay in search mode with first Red LED flickering fast ?Any body that can advise here? Regards Gert