hybridfree/eevblog-posts huggingface dataset:
Adjustable Cosntant current load quetsion - Page 1
Forum section: electronics / beginners

author: khatus
author_rank: Regular Contributor
timestamp: August 13, 2025, 02:17:04 pm
content: This is the adjustable constant current load I want to build. My question is whether the ground connected to the MOSFET's source is different from the ground used by the op-amp and the TL431 IC?

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: August 13, 2025, 02:42:30 pm
content: All are the same ground reference. Additionally I built a near-identical circuit to this recently, but I added a fuse + reverse-polarity protection diode to protect the FET.Something to also be aware of is that when a load is connected between pos + neg of the IRFP260 (FET), the device-under-test (DUT) will see a "short-circuit", before the opamp is able to regulate the current. That can be seenherein this simple Falstad simulation. There's various solutions to overcome this initial "short-circuit".Edit:In case you're curious,thisis the design I went with. Sadly it's significantly more complex, but it overcomes various problems which are written about in that thread.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 13, 2025, 05:37:21 pm
content: Why did you encircle dots? Dots are just connections between wires, they have no additional meaning.It is also a bit fishy that "earth" symbols are used for "GND". They are both a reverence for a "zero volt" reference, but they do have different implied meanings. But for the rest, it's pretty safe to assume that all "earth" symbols are connected to each other.

author: MathWizard
author_rank: Super Contributor
timestamp: August 18, 2025, 12:52:40 am
content: Now I used to think putting caps around a TL431 would always make it more stable, because it's a reference voltage, and surely caps make voltages more stable. But now I'm learning that's not the case for op-amps, and in particular the TL431 seem to only like very,very small cap's or very,very large caps. Maybe it still helps for near DC tho, I can't remember.Have a look at the datasheet for the charts relating to AC properties.Now I just made an TL431 Vref circuit in a temp-controlled oven. I never added any caps, I'll have to try it with some, like it did on the TL431 Vref in a PSU I built, and see what happens.

author: magic
author_rank: Super Contributor
timestamp: August 18, 2025, 05:51:58 am
content: You can supply the opamp with negative voltage, not ground, but the other two must be connected together for this circuit to work.
Adjustable Linear LDO - Page 1
Forum section: electronics / beginners

author: raff5184
author_rank: Regular Contributor
timestamp: March 20, 2020, 08:14:46 pm
content: Hi,I'm trying to use this AZ2117-ADJ LDOhttps://www.diodes.com/assets/Datasheets/AZ2117.pdfThere are few things that are not clear.1) What is Vref in this LDO? Is it the reference voltage internally used to measure and set the output voltage?2) I used figure "Typical Applications Circuit" and the relative formula for Vout. I was expecting that, for instance with R1=10k and R2=5.6k, I would get Vout = 1.98V. Or with R1=R2=10k Vout = 2.57V. But that's not the case, I only get Vout less than 1V.3) How do I choose R1 and R2 if I only have 1 equation? I want to dissipate the minimum power possible over the resistor divider.Obviously I'm missing something in the working principle of the device. Any help appreciated.

author: wraper
author_rank: Unknown
timestamp: March 20, 2020, 08:23:28 pm
content: Quote from: raff5184 on March 20, 2020, 08:14:46 pmDunno how it's not clear. Page 3, parameter on the top.QuoteIt's the same as LM317https://circuitdigest.com/calculators/lm317-resistor-voltage-calculatorhttp://www.reuk.co.uk/wordpress/electric-circuit/lm317-voltage-calculator/QuoteIt's not possible to get less than 1.25V output unless having additional negative supply to bring voltage on ADJ pin below GND. You should have connected something wrong.

author: raff5184
author_rank: Regular Contributor
timestamp: March 22, 2020, 07:45:37 pm
content: thanks for the resources. It works as expected now
Adjusting Frequency on an LED Flasher - Page 1
Forum section: electronics / beginners

author: eev_carl
author_rank: Regular Contributor
timestamp: February 10, 2018, 02:04:45 pm
content: Hi,I've implemented this LED flasher circuit but I can't visually discern the flashing. I verified with a scope that there is oscillation, but the frequency is 47.8 Hz rather than the 12.5 Hz listed in the description of the circuit. I have different PNP and MOSFET transistors: 3906 and 2n7000 respectively.Am I able to tweak the frequency with simple R or C substitutions or do I need to expand the circuit?Thanks,Carl
Adjusting input voltage of Technics Hifi Equalizer to work in the EU - Page 1
Forum section: electronics / beginners

author: FBMinis
author_rank: Regular Contributor
timestamp: September 07, 2021, 01:56:14 pm
content: A friend gave me his Technics equalizer he brought from the USA here to Portugal, he told me "it should work as is" but looking at the setup and considering they use 110V in the USA compared to 220V here, I am confused.Here is the setup as he gave it to me:here is the schematic for the device (under the chassis there is a rotary switch to set input voltage):Do I just need to set the module to 220V and replace the US plug with an EU plug?What was the logic behind using the transformer to convert 220 to 110 and having the module set at 240? He told me it was working like that (I have yet to test it but the fuses are intact).

author: Benta
author_rank: Super Contributor
timestamp: September 07, 2021, 04:02:20 pm
content: Replacing the plug and setting the voltage should be enough. Make sure that someone hasn't fiddled with the switch.

author: FBMinis
author_rank: Regular Contributor
timestamp: September 07, 2021, 05:15:07 pm
content: What would happen if the unit was set to 240V while powered through the step down transformer (110)?

author: wraper
author_rank: Unknown
timestamp: September 07, 2021, 05:38:07 pm
content: Quote from: FBMinis on September 07, 2021, 05:15:07 pmNo damage will happen. Probably it would still work with reduced performance since it's fully analog and reduced voltages likely won't make it completely inoperable.

author: FBMinis
author_rank: Regular Contributor
timestamp: September 07, 2021, 10:48:55 pm
content: The reason I asked was that the previous owner told me this setup was working here in Portugal with the 220V being converted to 110V and module set to 240V, which confused me.

author: BrokenYugo
author_rank: Super Contributor
timestamp: September 07, 2021, 11:20:34 pm
content: Probably best to set to 240 in a nominally 230V country, unless your service measures in the 220-230 range.
Adjusting transformer feedback frequency - Page 1
Forum section: electronics / beginners

author: gkmaia
author_rank: Frequent Contributor
timestamp: February 26, 2020, 12:25:30 am
content: I've got a scope I am working on for quite a while and the HV transformer was dead so I had to make a new one.As I have two of these scopes I toke the transformer of the working one out and reverse engineered it. When tested with 60Khz frequency and 10% of the actual voltage they output exactly the same values.The thing is, when I tested the transformer in circuit the feedback winding produced the correct voltage but its frequency was 300khz and because of that my R457 in the RC is starting to smoke.The right frequency is 60Khz.I am wondering is there is a way to tweak this circuit to better work with my transformer and reduce the frequency from 300khz down to 60khz.Is it something to be done at R/C 457 or on the feedback drive circuit prior to C455?Or is C455 that defines the frequency while charging and discharging? If it is... adding capacitance will slow the cycles?

author: tautech
author_rank: Super Contributor
timestamp: February 26, 2020, 09:49:13 pm
content: I'd strongly suspect the high value HV divider resistors on the secondary side have drifted and the resultant voltage feedback is now too high causing the primary switching to operate outside its design parameters.
Adonstar AD246s-M software - Page 1
Forum section: electronics / beginners

author: ME
author_rank: Frequent Contributor
timestamp: June 08, 2025, 03:26:04 pm
content: Hi folks i have the Adonstar AD246s-M microscope , I saw one one review where it has meashuring software via a Qr code,Does anyone know where i can find this to download without using QR codes?.

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: June 09, 2025, 07:51:46 am
content: I think you have to download from here:https://andonstar.com/download/
Adruino Max LEDs per GPIO - Page 1
Forum section: electronics / beginners

author: sy
author_rank: Regular Contributor
timestamp: November 06, 2023, 06:11:13 am
content: A quick search from Google, "GPIO are often limited to around 20mA and taking the Arduino Mega for example, some GPIO rails can deliver 100mA max, so that would only be 5 LEDs on at a time."If this means I can only control up to 5LEDs per GPIO due to a current limit, would it be possible to put a unity gain buffer in between to provide the extra current?

author: golden_labels
author_rank: Super Contributor
timestamp: November 06, 2023, 07:11:58 am
content: Arduinos’ output current is limited by their microcontrollers. Note the plurals: there are different Arduino devices with different microcontrollers.For example ATmega328 must not exceed 40 mA per I/O pin, and 200 mA total (for the entire device, not only I/O pins). Typical characteristics for I/O pins are specified up to 20 mA, but even at this current the output voltage drops by 1 V (at VCC = 3 V).Therefore: yes — you are limited to a few LEDs at a time. But “at a time” is crucial here. Indicator LEDs are usually not being run continuously. Instead, they are turned on and off in sequence. So in practice it’s rare to actually power more than one LED at a time.If you need larger current for whatever reason, a separate buffer/driver chip is not needed for simple LEDs. Just use an NPN transistor as either a switch incommon emitterconfiguration (remember about a resistor at the base!) or incommon collectorconfiguration (be sure the voltage drop is not limiting voltage available to the LED too much). In both cases remember that LED must have its current limited with a resistor too.(1)You will need proper buffers and drivers, if the signal has to be clean and quickly switching, or larger currents are involved.(1)Theoretically true for connecting directly to I/O pins, but AVR controllers are pretty forgiving in that matter. Not good enough for production, but sufficient for learning.

author: Psi
author_rank: Super Contributor
timestamp: November 06, 2023, 07:29:52 am
content: If you select a very efficient type of LED (usually they're orange) you can run them from 1-2mA and they are plenty bright enough.So you could run 30 of those off a single GPIO output .
ADS8319 ADC issues - Page 1
Forum section: electronics / beginners

author: joshendy
author_rank: Newbie
timestamp: October 14, 2020, 04:15:00 am
content: Hello,I've recently had a PCB made with the ADS8319 ADC on it and am having some real issues reading from it. I have the chip configured in it's "3-Wire CS mode w/out busy indicator" and connected to my STM32L4 micro like so:Then on the STM32 I'm doing this (dwt_delay is a microsecond delay):Code:uint8_t adc_read(uint16_t* result) {uint8_t data;HAL_GPIO_WritePin(SPI2_CS_GPIO_Port, SPI2_CS_Pin, GPIO_PIN_SET);dwt_delay(2); // Delay at least 1400nsHAL_GPIO_WritePin(SPI2_CS_GPIO_Port, SPI2_CS_Pin, GPIO_PIN_RESET);if (HAL_SPI_Receive(&hspi2, data, 2, 100) != HAL_OK) {return 0;}*result = ((uint16_t)data << 8) | data;return 1;}As per the ADS8319 manual pg. 20 (https://www.ti.com/lit/ds/symlink/ads8319.pdf) the CONVST (CS) pin needs to be taken high for at least 1400ns, during this time the chips data output will go tristate and then upon the CONVST pin going low the data output will be driven and at that stage it's just pulsing the clock 16 times and reading the 16 bit result. However all I ever get from this is an initial unexpectedly low value and then zeros after that. I have the ADC hooked up to a opamp that's biased by a rail splitter outputting 2V5 so I'd expect the ADC result to be half scale (~0x8000).Here's what it looks like on the scope at first power: (Blue is CONVST, red is SCLK and green is SDO)It looks to be alive and working here, the SDO goes high upon CONVST low and appears to change on the falling SCLK pulse as described in the manual. However on subsequent readings:The ADS8319 seems to just stop working and the SDO pin is just floating/discharging.Has anyone got any clue as to what may be going wrong? Any help would be greatly appreciated. I can supply more info if I've left anything out.Thanks,Josh
ADS8584S Timing Diagrams Questions - Page 1
Forum section: electronics / beginners

author: SethGI
author_rank: Regular Contributor
timestamp: September 27, 2020, 08:17:33 pm
content: Hi everyone,I'm reading through this datasheet, and I got a bit confused by some of the timing diagrams:https://www.ti.com/lit/ds/symlink/ads8584s.pdf?HQS=TI-null-null-digikeymode-df-pf-null-wwe&ts=1601232455191#page=26&zoom=100,0,689On Page 43, it says data is available at the falling edge of ~CS/~RD (Event 3). But, the timing diagram doesn't seem to align like that. What am I missing here? Would I be able to sample at the falling edge of ~CS/~RD, or would that result in some incorrect data? If anything, it looks like data is available at the __rising__ edge.Also, I don't quite see how I would do multiple consecutive reads (at the full 300KS/s). Normally I would expect to just leave the CONVST pins high, and it would just spit out data at the sample rate. It doesn't show that happening in timing diagrams (it's always one sample per channel, followed by another CONVST pulse. Would I have to manually pulse CONVST to sample? That seems wrong...Any insight appreciated!Thanks,Seth
ADUC7023 altium library - Page 1
Forum section: electronics / beginners

author: Eliza
author_rank: Contributor
timestamp: January 26, 2021, 05:29:16 am
content: Hello,I want to design ADUC7023 in Altium designer.Could you send me its library?

author: tooki
author_rank: Super Contributor
timestamp: January 27, 2021, 01:19:21 am
content: Do it yourself. 1. This isn’t a symbol/footprint service. 2. Analog Devices has those on the product page already!

author: Eliza
author_rank: Contributor
timestamp: January 27, 2021, 04:06:26 am
content: Ok, thanks
ADUC7023 programming - Page 1
Forum section: electronics / beginners

author: Eliza
author_rank: Contributor
timestamp: January 19, 2021, 09:00:58 am
content: HiCould you tell me that which language can I use to program ADUC7023 IC?

author: Zero999
author_rank: Super Contributor
timestamp: January 19, 2021, 11:33:39 am
content: It's an ARM based microcontroller, so use whatever language you like, which has a compiler which supports it, but C and assumbler are generally used nowadays.Analog provide sofware and a evaluation kits to help.https://www.analog.com/en/products/aduc7023.html#product-evaluationkit

author: Eliza
author_rank: Contributor
timestamp: January 22, 2021, 06:24:55 pm
content: Thank you so much
Aduino All in one Signal Generator & Test Meter - Page 1
Forum section: electronics / beginners

author: Kedar264
author_rank: Regular Contributor
timestamp: February 09, 2015, 03:22:41 pm
content: see my arduino based multifunction test equipment,currntly ony shows vols but im adding every possible featurewatch on Youtube and please give me review and your thoughts.

author: dentaku
author_rank: Frequent Contributor
timestamp: February 09, 2015, 04:14:07 pm
content: I like your project. I have one of these Nokia displays but the backlight is blue. I like the white backlight much better.By the way... I see that your Arduino IDE uses a custom font and font size. What font is that?
Advance Op-Amp Learning Resources - Page 1
Forum section: electronics / beginners

author: TechJunkie97
author_rank: Contributor
timestamp: March 01, 2018, 02:44:46 pm
content: Hi, I tend to lose track of the videos when Dave starts talking about little bit complex op-amp circuits. So, I wanted to learn about op-amps at a deeper level. All the Op-Amp tutorials talk about basic negative feedback loops using resistors. Dave also talked about Schmitt trigger, but he remained away from general positive feedback loops. I would like to know how other components such as capacitors, inductors, transistors and other stuff work in feedback loops. Can someone point me towards nice resources related to this topic?Thanks,Jas

author: mtdoc
author_rank: Super Contributor
timestamp: March 01, 2018, 03:07:08 pm
content: Op Amps for Everyone

author: rstofer
author_rank: Super Contributor
timestamp: March 01, 2018, 03:10:10 pm
content: Those feedback loops are going to be the same thing that is covered in Control Systems. Laplace Transforms (and their inverse) will be spilling out all over the place. You will consider the op amp to be G(s) with essentially infinite gain and the feedback loop will be H(s). The closed loop equation will be G(s)/(1+G(s)H(s)).https://www.electronics-tutorials.ws/systems/negative-feedback.htmlActive Filters is another area where the feedback loop is not simply a resistor.http://www.ti.com/lit/an/sloa049b/sloa049b.pdf

author: danadak
author_rank: Super Contributor
timestamp: March 02, 2018, 08:56:13 pm
content: Here is a resource on IAs that is excellent -http://www.analog.com/en/education/education-library/dh-designers-guide-to-instrumentation-amps.htmlRegards, Dana.
Advanced bank switching for SBC - Page 1
Forum section: electronics / beginners

author: thingsis
author_rank: Newbie
timestamp: October 16, 2015, 08:08:06 am
content: Hi,I am building my first Single Board Computer after having done numerous other electronic projects. I have this idea for the memory map that I would like to bounce off of you guys and get some input as to how this could be achieved. Basically it goes like this:I have two memory chips: 16kB ROM and 32kB RAM. Let's assume my address space is 32kB for this. Those 32kB are mapped to the ROM and half the RAM. So far so good. But here are the two "ideas"1) When the computer boots, it copies the ROM to the 16kB of RAM that are currently not mapped and then swaps the ROM and that part of the RAM, resulting in only the 32kB RAM being mapped. My problem is not the swapping, but the writing to the RAM while it is not mapped.2) Here we go: The ROM chip is actually 128kB Flash. The buttom 16kB of this is the ROM code. I want to use the remaining space is an I/O device (mass storage). Next to having mass storage this serves another purpose. The chip can be programmed in system that way - but only if I can access the whole thing!The ROM chip is a Microchip SST39SF010A.Thanks for any help!

author: Ian.M
author_rank: Super Contributor
timestamp: October 16, 2015, 09:52:11 am
content: 32K is a *very* unusual size for an address space. Are you using A15 to distinguish between memory and I/O in a 64K address space? If so, you might do better to reduce the I/O space to 16K by using A15 & A14 to decode it letting you map the 16K ROM page and the RAM simultaneously.One trick that helps is that on startup, all read accesses in the bottom 16K should be mapped to the ROM and all write accesses mapped to the RAM. This allows you to use a simple loop that reads each byte and writes it back to the same address to copy ROM to RAM. Another trick is to simply double map the ROM so it appears at the reset vector for N reads after reset, overriding the RAM, just long enough to execute a jump to the ROM's usual address.If your cycle time permits it and you can source a pair of NOS 74F189 or better 74F189A, it becomes fairly trivial to expand an address bus by 4 bits, with 16 fully selectable pages from a pool of 256. Seehttps://www.eevblog.com/forum/beginners/z80-single-board-memory-bank-switching/msg268606/#msg268606. You can get there by other means, but either you need a metric s--tload of logic, or you have to deal with data in and out being on the same pins of the mapping RAM.

author: thingsis
author_rank: Newbie
timestamp: October 16, 2015, 10:21:14 am
content: Hey Ian,thanks for your reply. The trick with distinguishing between read and write at startup sounds really good! The address space is actually 64k. We are only looking at 32k of that at the moment for the sake of this problem. The other 32k will be mostly RAM with some I/O.Thanks again!
Advanced Test Jig for Series 500 Audio Modules: I sure would like to have one! - Page 1
Forum section: electronics / beginners

author: GrievousAngel
author_rank: Contributor
timestamp: November 10, 2024, 08:55:44 pm
content: I have several Series 500 Extension Jig Adapters however . . . they fall short IMHO!I several questions, besides ... What are others using & doing for Series 500 DIY testing adapters?1. 500 extension jig design that deal with DUT balanced I/O when being measured by single-ended test devices (w/o using a calculator)?Balanced audio signal generators are available at OK prices but Audio AC Voltmeters are typically not as cheap. Of course, if handy, DAW ADDA devices are great. BTW ... a better stand-alone ADDA module is the RME ADI-2 FS Pro. Check it out as it is a reference grade listening device as well.2. Since most test gear share the negative (GND) terminal with its signal path system GND and maybe its chassis, w/o differential probes/modules (or even in desperation considering grabbing a gray-like VAC 2P to 3P power adapter thingy, taking proper measurements easily become a challenge. Any ideas on resolving this problem? Anyone tried that CHEAP China Differential Module for ~ $80USD? DIYer diff probe/module?3. I know of no 500 test jig designed to easily take two simultaneous measurements 'm referring to two measurement devices on the DUT Input and/or Output.Ideas and suggestions?Cheers, Billy
Advantage and Disadvantage of BCM and DCM?  - Page 1
Forum section: electronics / beginners

author: Patrick66
author_rank: Regular Contributor
timestamp: January 07, 2024, 02:08:52 am
content: What are the advantages and disadvantages of BCM and DCM when compared with each other?

author: Patrick66
author_rank: Regular Contributor
timestamp: January 08, 2024, 03:59:07 pm
content: Hello Sir, can explain a little about the type of power losses? what is Pcu Poff ?
Advantech PCI-1612B - what is it? - Page 1
Forum section: electronics / beginners

author: gcardinal
author_rank: Unknown
timestamp: August 21, 2016, 08:33:40 am
content: I came across a few Advantech PCI-1612B cards and did a fair amount of googling - but just wasnt able to find out what those things are actually used for?What are the most common practical application?Can their for instance be used to drive stepper drivers?

author: mariush
author_rank: Super Contributor
timestamp: August 21, 2016, 08:48:07 am
content: http://www.advantech.com/products/1-2mlk9c/pci-1612/mod_d5caf728-9a69-4bed-93f9-c919d71784a24-port RS-232/422/485 PCI Communication CardUniversal PCI v2.2Speeds up to 921.6 kbps for extremely fast data transmissionSupports any baud rate setting4 x RS-232 or RS- 232/422/485 portsSupported operating systems: Windows 7/8/10, and Linux.XR17V354 UART with 256-byte FIFOs

author: gcardinal
author_rank: Unknown
timestamp: August 22, 2016, 11:29:12 am
content: Quote from: mariush on August 21, 2016, 08:48:07 amThank you - I did get so far my self. But what are the real world practical application of this cards?

author: cs.dk
author_rank: Unknown
timestamp: August 23, 2016, 03:34:34 am
content: They are often used for CNC-machines. Lathes, mills, etc.

author: Bukurat
author_rank: Regular Contributor
timestamp: August 23, 2016, 11:35:01 pm
content: Its 4 serial ports. You could set them all to RS-232 and drive 4 serial printers or 4 fax old fax machines or any combination. Look "serial communications"for ideas.
Advice about transimpedance amplifiers - Page 1
Forum section: electronics / beginners

author: LoveLaika
author_rank: Frequent Contributor
timestamp: June 20, 2020, 04:08:39 am
content: I need some advice regarding transimpedance amplifier circuits. I'm working with silicon photomultiplier, and some circuits that I've built work fairly well. My circuits consist of an SiPM (in this case, the MicroFJ-60035) with an op-amp in a transimpedance amplifier configuration (TI's OPA656). For reference, I've linked to two PDFs below: one showing common readout circuits and one of the datasheet of the SiPM. The TIA circuit I'm using is in the readout PDF, figure 13, left side.The basics of a TIA use a capacitor and resistor in parallel to turn a current output into an equivalent voltage output. It works fairly well with a single SiPM, so I tried to put more SiPMs in parallel to construct arrays. However, when you put SiPMs in parallel, you increase the input capacitance and you increase the noise from each one when you connect them all to one TIA, and one output. With my SiPM, the datasheet states that the anode has a capacitance of 4.14 nF; with 4 SiPMs, that's 16.56 nF, and with 16 SiPMs, that's 66.24 nF. Given the large values, what parameters do I have to look for in an op-amp that can handle such a high capacitive load at the input?Readout:https://www.onsemi.com/pub/Collateral/AND9782-D.PDFDatasheet:https://www.onsemi.com/pub/Collateral/MICROJ-SERIES-D.PDF

author: awallin
author_rank: Frequent Contributor
timestamp: June 20, 2020, 10:53:49 am
content: to pin down a design that works you will need to specify how much light you are detecting (and what photocurrent that produces), and what bandwidth (or pulse length) you are hoping to achieve.large source-capacitance might not be a problem if you only have slow signals..

author: LoveLaika
author_rank: Frequent Contributor
timestamp: June 21, 2020, 04:33:28 am
content: Thanks for your answer. I'm dealing with very fast signal times, like in the nanosecond range. How does the pulse length correspond with the op-amp's own bandwidth? Obviously, the op-amp bandwidth must be very fast since the pulse length is very fast, but if the pulses are in the nanosecond range, you would need an op-amp whose small signal bandwidth is in GHz? What about slew-rates other types of op-amps?

author: TimFox
author_rank: Super Contributor
timestamp: June 21, 2020, 08:28:44 pm
content: Do you have enough signal that you can run the anode current into a 50 ohm termination and use high-speed pulse amplifiers? A TI amplifier can probably offer less noise, but routing fast signals through coax is easier to do.

author: LoveLaika
author_rank: Frequent Contributor
timestamp: June 22, 2020, 03:27:40 pm
content: Do you mean route through an off-board, external amplifier module? We managed to feed the SiPM output directly to an oscilloscope via 50-ohm termination with no amplification, and that worked well enough for our tests. Issues just came about when we tried to feed the signal to a pre-amp on board.
Advice and recommendations on an electronic gyroscope - Page 1
Forum section: electronics / beginners

author: brightspark96
author_rank: Newbie
timestamp: December 26, 2015, 11:41:46 pm
content: Hey there folks!I am looking for an electronic component which can tell me it's orientation and nothing else.I am going to be using a rather large number of them so I am looking for something as cheap as possible!They also need to be very small, I am wondering what size the smallest ones available would be? I have found some which are 25mm square but I would like something smaller, if possible. 10mm square would be an upper limit in an ideal world. I've looked around online I am just not sure if I'm looking in the right places!!!Edit: It needs to be 3-axis.Thanks in advance!!!

author: Brumby
author_rank: Unknown
timestamp: December 27, 2015, 02:23:43 am
content: Absolute orientation in all 3 axes is not straightforward, but it's easy to work out which way isup/down.Is that what you need?Do you also want to know about movementalongthe X, Y and Z axes?Do you also want to know about rotationaroundthe X, Y and Z axes?

author: Maxlor
author_rank: Frequent Contributor
timestamp: December 27, 2015, 03:14:39 am
content: So, look in the right digikey category and sort for price? Size shouldn't be an issue, 3x3mm and 4x4mm are common sizes.http://www.digikey.ie/product-search/en?FV=fff4001e%2Cfff8048b&mnonly=0&newproducts=0&ColumnSort=1000011&page=1&stock=1&pbfree=0&rohs=0&quantity=4000&ptm=0&fid=0&pageSize=25Wow, they're really come down in price. When I used one of those chips in a hobby project a couple of years ago, it cost like 5 times as much!
Advice for installing dc-dc charger in van - Page 1
Forum section: electronics / beginners

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: November 14, 2024, 04:09:47 pm
content: I am still a little lost as to wire gauges and what my alternator is to see if suitable for a specific dc-dc charger.I have this one in mind for good price to feature ratio as the bigger ones are double or more and don't think I need that much as this is just to supplement solar in these shorter days or if they would even be compatible with the alternator:https://www.12voltplanet.co.uk/sterling-power-bb1225-battery-to-battery-charger-12v12v-25a.htmlI am not sure what power my alternator is so will have to wait to find out. I looked in the manual today and could not see mention of an alternator in terms of specifications and forgot to look under the hood when I went outside and am now inside for the evening.Also what wire gauge should I use? A support rep on 12 volt planet wrote me that 50a cable with 30a fuse will suffice. I am confused by this since I read an article on split chargers today that stated you should choose wire that is the amperage of the charging unit (which would be the alternator right?) but also that the battery can also be a charging unit so you should add both together. I know the battery is 60 or 80, can't recall exactly and then also add the amps of the alternator, currently unknown but probably up to 100 or more so why did they tell me only 50a wire? Does the above advice on split charging not apply in this case of dc-dc charging?Any other considerations for setup? I thought initially I would have to drill another hole to get to the engine from the cab however I remembered I have a whacking great 100mm hole in the floor for an intake fan so I could run it through there couldn't I? I believe there is space to fit the wire without interfering with the fan. That would make life somewhat easier.

author: NE666
author_rank: Frequent Contributor
timestamp: November 14, 2024, 06:33:41 pm
content: Have you tried reading the manual? Page 6 and page 10 in particular. Cabling and fusing requirements clearly stated and diagramed for you.https://www.12voltplanet.co.uk/user/downloads/Sterling-BB1225-Battery-To-Battery-Charger-manual.pdf
Advice for making DIY starter battery charger from solar DC - Page 1
Forum section: electronics / beginners

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: October 20, 2024, 08:52:56 am
content: Hi,I have a solar setup in my van. Briefly...300w solar, epever tracer 4215 bn solar charge controller, 105ah lifepo4 battery. Common items connected to fuse block.I know that buying chargers is relatively cheap, at around £30, however they come with things I don't want like being a power pack and other such undesired bells and whistles. Since the system is DC, rather than buy an inverter I have already connected my laptop and phone directly to the fuse block, with their relevant voltage step downs so I thought why not also do the same with this?I thought why can't I just make a connection from the fuse block and run it with crocodile clips to the battery. Are there any particular warnings doing this?I asked on a solar forum about doing this and got mostly ridiculed being told I was overcomplicating and overthinking a perfectly simple solution of just buying one and that they would to pay to watch me blow myself up. Not very supportive comments and I found that extremely narrow minded to be punished for experimenting. I thought perhaps a dedicated electronics forum might be more encouraging in this regard.If the system is 12v do I have to regulate the amperage going to the battery from the fuse block? I don't understand what would dictate the current in this case because from what I have read the devices dictate how much power is drawn normally so what would happen in the case of a starter battery? Not knowing this I decided to buy a step down device which is variable voltage but is 1.5 amps, I believe, so if I set the voltage to 12v then the amps should charge steady into the battery at around 1.5 right?The reason I thought this would be suitable is the commercially available mains trickle chargers are rated at similar currents so I thought I would just try and emulate them.Now are there any other safety considerations to doing this? I have seen that overcharging is something to be aware of. Is there a DIY way to add in overcharge protection simply/cheaply? Even without it though I am thinking that so long as I am monitoring the battery charge with mulitmeter and take it off just as it reaches, or nears, 14.4 volts it should be ok? Please let me know if not?I know I should not leave it unattended for this reason and I wouldn't intend to. This solution is just for times when the battery goes so low as to not be able to start the engine which has happened to me on numerous occasions. There are cheap solar chargers available but I thought why not tap into the 300w/battery supply I already have available?I wanted an off-grid solution to get the engine to start again and then the alternator would take over.
Advice lighting custom desk lamp - Page 1
Forum section: electronics / beginners

author: Zinger
author_rank: Contributor
timestamp: May 13, 2021, 12:37:42 pm
content: I need some advice lighting a custom desk lamp. I'm looking for something like a small 3W RGB LED with built-in driver and PWM or a small driver board for a 3W RGB LED. It should run off 5 or 12V. I've found a lot of devices that are close but not exactly what I need.My design is a low profile plastic base, ~3"x3"x.75", with a 12" tall baseball bat standing in the center. The bat will glow soft white, be dimmable and have a few color effects. I'm making a small run of them for a group of friends. Since these will gifts, I don't want to compromise on longevity, EMI, safety, etc. I'd hope to build them for ~$20/unit but it's a small run so spending more for quality won't break me. I'd probably rethink the project if it got much above $30/unit.Naively, I built the prototype with a 3W RGB LED, an Arduino and some transistors. That worked but it was a Frankenstein-mess, wasted a lot of power, was way too hot and would probably burn itself out in real life usage. Trying to shrink it down to something that fits in the base, I realized I was over my head.I've looked at several parts from hobby suppliers like Adafruit and SparkFun. I've also looked at I2C parts, though I'm brand new to I2C. This part seems promising, but I don't know if it will be bright enough.https://www.sparkfun.com/products/8579I don't have a sense for how mcd compare to watts.

author: Zero999
author_rank: Super Contributor
timestamp: May 13, 2021, 03:58:27 pm
content: Is colour rendering important? RGB isn't the best. You'll need to incorperate white and/or other colours, for good colour rendering.PWM can cause problems with stroboscopic effects, on moving parts, unless the frequency is very high.
Advice needed about wiring a 10 pin RJ45 port for ethernet pass-through - Page 1
Forum section: electronics / beginners

author: Marmotta
author_rank: Contributor
timestamp: January 13, 2020, 05:01:36 pm
content: I'm building an PC-in-an-Xbox One system and was planning on reusing all the I/O from the console on a custom PCB where everything would pass through to the PC motherboard. Unfortunately, the ethernet port seems to be causing me more problems than I'd anticipated.I'd foolishly believed that I could have just used the port as a passthrough, but it seems that there is continuity across all the though-hole pins, yet conversely I can't get any continuity from those pins to the connections on the port. I can't get any further information on the ethernet connector as it's a Foxconn part. I've included some pictures of the motherboard as well - pins 5 and 6 appear to be connected to GND via a capacitor and all the others seem to just go straight to the Realtek MDIO Ethernet controller on the motherboard.

author: SeanB
author_rank: Super Contributor
timestamp: January 13, 2020, 06:03:08 pm
content: You have a ethernet port with integrated magnetics, done so they have the port and the required isolation transformer in a single part, saving board space and saving on assembly, plus the 2 port LED's are integrated into the top of the port next to the latch, making it compact.. Look up the part number, or look for other datasheets for similar parts and you will find information.

author: wraper
author_rank: Unknown
timestamp: January 13, 2020, 06:05:01 pm
content: There are ports which are bare connectors with pins directly connected to wires. Other type has integrated transformers.

author: pcmad
author_rank: Regular Contributor
timestamp: January 13, 2020, 11:01:03 pm
content: rj45 connector are 8 wire max

author: Yansi
author_rank: Super Contributor
timestamp: January 14, 2020, 12:11:59 am
content: Quote from: pcmad on January 13, 2020, 11:01:03 pmSure, on the RJ45 side yes, but the two more pins on the PCB side are the center taps of the TX/RX transformers.

author: pcmad
author_rank: Regular Contributor
timestamp: January 17, 2020, 04:32:41 pm
content: Quote from: Yansi on January 14, 2020, 12:11:59 amor couldbe for the active led

author: oPossum
author_rank: Super Contributor
timestamp: January 17, 2020, 05:00:32 pm
content: There are 10P10C modular connectors that are the same size as 8P8C ("RJ-45"). I'm not saying that is what is on the PCB in the first post, but they do exist and would have the same PCB footprint.

author: Daixiwen
author_rank: Frequent Contributor
timestamp: January 20, 2020, 11:22:59 am
content: No Yansi is right on this one. There is no transformer on the PCB between the PHY and the connector, so you must use a connector with integrated magnetics. The two extra pins are for the center taps of the transformers.
Advice needed - I2C Bus & I2c PCB trace - Page 1
Forum section: electronics / beginners

author: Docara
author_rank: Regular Contributor
timestamp: July 17, 2018, 04:11:32 pm
content: Hello Everyone,I'm just about to start combining (basically) a number of schematics (with tweaks) from datasheets on to a double sided PCB. Other than hobbyist 1 or 2 chip boards, this one is going to be the most complicated one I've done.The project is a glorified switch matrix and LED driver with an RTC and Elapsed Timer with a SPI CAN interface linked to a third uC.Ultimately, it will have 2 uC on board (probably Nanos) and if memory serves me right 4/5 devices connected on the 12C bus. Probably the uC's will be at the ends to allow for future motor control.1.) Now, I know there is a maximum capacitance on the 12C bus of 400pF and 10K Pull-ups are required (initial value). Are these pullups needed for every device, at one end, both ends, roughly in the middle or it doesn't matter as long as they are connected?2.) Are there any specific requirements to routing of the SDA and SCL lines.3) Any general advice for PCB layout (Kicad or Easyeda and JLCPCB manufactured)ThanksMatt

author: HB9EVI
author_rank: Frequent Contributor
timestamp: July 17, 2018, 04:32:02 pm
content: in practice it doesn't matter much, where the pullups are placed. of course, the higher the clockrate goes, the more you have to watch for both - the place for the pullup and the routing on the pcb. For the classical speeds of 100kHz and in most cases also for 400kHz it's not much critical. Basically avoid digital lines from coupling in analog ones and vice versa.

author: rstofer
author_rank: Super Contributor
timestamp: July 17, 2018, 05:37:05 pm
content: There is a standards document for I2C published by NXPWhat you will find is that the pull-up resistors usually need to be a good deal smaller than 10k. I often wind up around 2.2k and that's a good number because the line drivers are limited to 3 mA and 5V / 3 mA is 1666 Ohms.https://www.nxp.com/docs/en/user-guide/UM10204.pdfhttps://www.nxp.com/docs/en/application-note/AN10216.pdfOTOH, it might work perfectly with 10k resistors. I just tend to go toward the minimum value to overcome any capacitance I can't account for.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: July 17, 2018, 06:32:00 pm
content: that's true; and the higher you go with the clockrate, the lower you choose the pullup; I normally use 4k7 or 2k2

author: Neilm
author_rank: Super Contributor
timestamp: July 18, 2018, 06:32:08 pm
content: Quote from: Docara on July 17, 2018, 04:11:32 pmYou only need one pullup resistor per signal (unless you are going something multi-board and don't want to have some of the boards in an undefined state). Check the standard for the rise times and adjust the pullups until you meet the requirements with a comfortable marginQuoteNo, although running the two lines side by side means that they will have a similar capacitance.QuoteSorry - I don't have any experiance in those.
Advice on 555 PWM led control - Page 1
Forum section: electronics / beginners

author: GadgetBoy
author_rank: Regular Contributor
timestamp: August 20, 2018, 07:05:26 am
content: So, I've been messing around with the venerable old triple nickel timer, never used it for a variable PWM before, every application I've used it before was for astable or stable multivibrator.So, here I am, cursing at it because I can't get it to work in PWM to save my life. Think maybe my components are bad, throw in some standard values for a 1Hz blink, and it's working fine. Put my components back in for PWM, nothing.Fast forward several hours of experimentation, and I've determined that the values of resistors I'm using are too low - it seems the triple nickel can't function if the values are too low. I redo my math to incorporate higher values, and it starts working right away (sorta... the range of adjustment isn't as wide as I'd like, but I'm figuring it out).So, I have it working, but my question is this - is there a sweet spot for the resistor values you use?Sent from my ONEPLUS A3000 using Tapatalk

author: Zero999
author_rank: Super Contributor
timestamp: August 20, 2018, 07:56:24 am
content: Please post a schematic.The 555 timer can be damaged if too lower resistor values are used, because they allow too much current to flow, resulting in too higher power dissipation and overheating.Try replacing the 555 timer and trying again with the high value resistors.

author: GadgetBoy
author_rank: Regular Contributor
timestamp: August 20, 2018, 10:14:41 am
content: The 555 is fine, after I started using higher value resistors, the PWM started working, I also figured out the range issue. My question was if there was a specific base resistor value I should work from. I'll whip up a schematic tomorrow, if you really want it.Sent from my ONEPLUS A3000 using Tapatalk

author: Zero999
author_rank: Super Contributor
timestamp: August 20, 2018, 11:20:23 am
content: As with many things, there's no hard limit for the minimum value.Refer to figure 12 on page 11 of the data sheet. Current flows through RAinto pin 7 of the 555. If RAis too low, the voltage on pin 7 will be higher, than it should be, when the discharge transistor is on, which will affect the stability and to the extreme, will stop the circuit working properly and could damage the 555. Unfortunately I didn't see a maximum rating for the current into pin 7, but the saturation voltage is specified at 8mA and going from the graphs, the minimum recommended resistor is 1k.http://www.ti.com/lit/ds/symlink/ne555.pdfIn general, it's good to keep the timing capacitor small, because large capacitors have generally poorer tolerance, leakage and stability.
Advice on a 6 layer stack up, analog, digital and Ethernet(LVDS) signals  - Page 1
Forum section: electronics / beginners

author: 2xA
author_rank: Newbie
timestamp: March 30, 2018, 07:06:35 pm
content: Hi,I could really use some advice with my PCB stackup.It contains analog 0-10V I/O, digital I/O 24V, earth, different power rails and LVDS.The board is for a computer controlled machine application with potentiometer as feedbackMy current stack up is---- earth and supply rails 0,035mm copper*** 0.2mm isolate prepreg---- GND 0,035mm copper*** 0.2mm isolate core---- analog signals 0,035mm copper and LVDS with a large distance between and a separeret power and GND plane below and above*** 0.6mm isolate Prepreg---- digital I/O and LVDS with a large distance between and a separeret power and GND plane below and above 0,035mm copper*** 0.2mm isolate core---- 24V power plane 0,035mm copper*** 0.2mm isolate prepreg---- digital I/O and relay signals 0,035mm coppershould I make the distance between the analog and digital even bigger? which would make the distance to the reference plane smaller.should I make another ground plane below the power plane as described here:https://aerospacepal.com/6-layer-pcb-stackup-emi-design/and what about the symmetri of the board?Could I drop the power plane and go to four layer?I really appreciate any advice you can give me.Kind regards2xA
Advice on an amplifier topology - Page 1
Forum section: electronics / beginners

author: TheBaconWizard
author_rank: Regular Contributor
timestamp: July 01, 2018, 10:21:50 am
content: So I'm learning about various amplifier types and came upon the following interesting circuitI wouldn't mind building something similar. But I don't quite understand the relationship between the two mosfets in each cell, what is the purpose behind strapping them together in this fashion?

author: Cerebus
author_rank: Super Contributor
timestamp: July 01, 2018, 01:21:55 pm
content: The clue is the voltage rails (±600V = 1200V overall) and the VDSmaxrating of the transistors (800V). As this is a class B topology it's quite possible for the entire rail voltage to appear across either the top half or the bottom half. Setting up the output transistors like this lets them share the voltage drop so that each pair might see 1200V, but each transistor will only see 600V and so stay within its VDSmaxrating.
Advice on building radio - Page 1
Forum section: electronics / beginners

author: cmumford
author_rank: Contributor
timestamp: September 04, 2020, 07:04:48 pm
content: I am considering building my own ESP32 controlled FM/AM radio. I've already created one on a breadboard using an ESP32, aSi4703 breakout board, and an OLED using a SSD1306 via I2C. I'm pretty happy with the result so far, am feeling ambitious (probably cocky), and want to go all the way to HD radio. I would really like to use theSi4689, which is a massive step up from the Si4703. There are no breakout boards, but I'm prepared to make my own.The Si4689 is a QFN-48 package, and I am hoping to solder it to aSMT Breakout PCB, so that I could prototype the circuit, and write the software first. My plan is breadboard the design from theSi468X Schematics and Layout Guide, and eventually design and fabricate my own PCB.Is the ESP32 up to the task? I haven't yet counted up the number of IO pins required by the Si4689, but aside from that, can anybody see why the ESP32 won't work?Will I be unable to make this circuit work on a breadboard? I know I'll be exceeding recommended lead lengths, and dealing with weird capacitance issues, but can a breadboarded circuit work?It looks like I will need to load firmware into the Si4689 upon each startup (seeAN649pg. 397). Any problem putting a 2MB ROM on a breadboard?Do I need to worry about licensing issues for digital radio, or is that already done by Silicon Labs? I'd rather not get into the project only to learn that the DAB/HD Radio features won't work unless flashed with a key of some kind.I'm off to dive into the programmer's guide, but wanted to ask these few questions first, just in case this was a totally insane and undo-able project.

author: HalfDeafChef
author_rank: Newbie
timestamp: December 08, 2021, 03:31:56 pm
content: Hi,I am interested in pursuing a similar project. Have you made progress on it? Did the ESP32 implementation work?