hybridfree/eevblog-posts huggingface dataset:
Can I test big Inductors/Coils with a insulation tester - Page 1
Forum section: electronics / beginners

author: tastychickenwings69
author_rank: Newbie
timestamp: November 14, 2021, 05:42:23 am
content: hiCan I test very big inductors/coils for isolation with my insulation tester without destroying anything in my tester it from the possible back EMF if there is any?

author: WattsThat
author_rank: Frequent Contributor
timestamp: November 14, 2021, 06:03:18 am
content: You don’t state what parameter/characteristic you actual want to check but since you’ve got an insulation tester, I’ll assume it’s insulation you want to test.Test between the individual inductor leads and core/feet/any metal. When there is no current through the inductor, there is no back emf. If there is any doubt, short the inductor leads together.

author: tastychickenwings69
author_rank: Newbie
timestamp: November 14, 2021, 01:54:22 pm
content: Quote from: WattsThat on November 14, 2021, 06:03:18 amI have a VC60B+ insulation tester and the coils I wanna test range from 1H to 10H, the test voltage will be 250V, 500V and 1000V.I hope this helps.

author: ejeffrey
author_rank: Super Contributor
timestamp: November 14, 2021, 03:01:08 pm
content: Measuring insulation on motor and transformer windings is a standard application of an insulation tester. It will be fine. The maximum test currents are small they won't wind up the inductance much even if the insulation is broken.
Can I trim a NFL? - Page 1
Forum section: electronics / beginners

author: LektroiD
author_rank: Frequent Contributor
timestamp: August 17, 2015, 04:27:21 am
content: I'm using an op amp to drive a mic input, seems in practice the level is too high. I put a trimmer in, and yes it works, but there's a lot of pops and crackles. Would that be down to the trimmer quality, or is there a better way to do this?

author: rs20
author_rank: Super Contributor
timestamp: August 17, 2015, 04:50:38 am
content: Does turning the pot really adjust the volume? Have you drawn the entire circuit, or left out a resistor from the - input to ground? Because what you've drawn there is a op-amp buffer circuit with a gain of 1, regardless of the feedback resistance (assuming an ideal op amp).Is it popping and crackling while it's just sitting there, or only when you adjust the volume?

author: dom0
author_rank: Super Contributor
timestamp: August 17, 2015, 08:02:45 am
content: There's something missing in your schematic.When using pots as a rheostat [adjustable resistor] it's often advisable to put some fixed R from the wiper to the end to avoid/lessen the problem you are describing.While adjusting the gain of amplifiers at audio frequencies is usually not very troublesome keep in mind that it changes many properties of the amplifier. Compensation for stability must be done at the lowest settable gain ; phase margin should be plenty as pots are not precision devices and will drift with wear.

author: LektroiD
author_rank: Frequent Contributor
timestamp: August 17, 2015, 08:53:47 am
content: How's this look? I also included the rest of the circuit...
CAN I upgrade a HP8648B to HP8648D ? - Page 1
Forum section: electronics / beginners

author: pigfun
author_rank: Newbie
timestamp: June 05, 2025, 11:46:34 pm
content: I have a HP8648B , when I destruct it , i find the A10 (Frequency Extension)is the same of HP8648D , so,my question is ,CAN I upgrade the firmware of HP8648B and make it to HP8648D ?

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: June 06, 2025, 07:13:28 am
content: A firmware update alone may not be sufficient in this case.https://www.youtube.com/playlist?list=PL2z3V9RkHQE3GPZQEZk_mDHWhFKax5S2Z

author: pigfun
author_rank: Newbie
timestamp: June 06, 2025, 10:36:16 am
content: thanks
Can I use 1:1 passive probes with 64pF shunt capacitance with a 1054z? - Page 1
Forum section: electronics / beginners

author: julian1
author_rank: Frequent Contributor
timestamp: February 21, 2017, 07:13:13 am
content: Does 64pF, imply actual compensation adjustment anywhere from 10pF - 64pF ?The probes are these,http://www.keysight.com/en/pd-1000000977%3Aepsg%3Apro-pn-10439A/11-2m-miniature-passive-probe?cc=US&lc=engIf not - then can I change the capacitor trimmer?

author: tggzzz
author_rank: Super Contributor
timestamp: February 21, 2017, 09:01:08 am
content: Quote from: julian1 on February 21, 2017, 07:13:13 amIt means the tip capacitance that loads your circuit is 64pF. *1 probes don't have a frequency compensation trimmer capacitor.They can be used with a 1054Z scope, with the standard performance limitations.

author: danadak
author_rank: Super Contributor
timestamp: February 21, 2017, 12:56:23 pm
content: Of course you have significant circuit loading, at 1 Mhz Xc ~= 2.5Kohms, quite low.Completely out of the question to probe a crystal oscillator circuitfor example, at the crystal.Regards, Dana.
Can I use 2*36V primary / 235V secondary transformer reversed? - Page 1
Forum section: electronics / beginners

author: mpuq
author_rank: Newbie
timestamp: September 09, 2017, 03:59:02 pm
content: Hi you all,This might be a stupid question, but I want to be sure before connecting anything to the mains.I happen to have two 800 VA 2*36V primary / 1* 235V secondary Ulveco transformers, that I dismantled from Fiskars UPS 08 units somewhat 10 years ago.Can those transformers be used backwards, feeding the mains voltage (Here in Finland that is 230 VAC) to 235 volts secondary and then using the 36V windings as secondaries?I guess those UPS units generated 72V AC and then transformed it to ~230 volts suitable for normally mains connected hardware.Thanks in advance.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 09, 2017, 04:05:51 pm
content: In principle it should work to run the transformer in reverse. However the voltage at the output might be slightly smaller, as usually the voltages printed on the transformer are for nominal load, thus they include the drop on the secondary side. So the output might be some 10%-20% lower - so more like 30-33 V at the output at nominal load.Depending on the original circuit, the transformer might not have a very good isolation. So chances are it might not be good enough for a SK2 application. At least it might not be tested for this. It would likely be OK if the secondary is connected to safety ground (PE).

author: mpuq
author_rank: Newbie
timestamp: September 09, 2017, 04:38:10 pm
content: Thank you for your reply Kleinstein.The isolation was actually my main concern, and I think that in the original application there hasn't been need for great isolation.I guess that just to be on the safe side, I will order a new transformer for my use, that has FI, VDE and S+ certifications.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: September 09, 2017, 04:59:35 pm
content: The majority of UPS use the transformer bidirectionally, with step down for charging. There may be taps for each mode, since to overcome losses you need somewhat lower turns ratio (less voltage reduction) for charging than for step-up.So the answer is yes, provided you sort out which taps are the right ones to use. Agree though that the UPS transformer probably wasn't designed to be used earth-free, which would call for better insulation to ensure safety.

author: mpuq
author_rank: Newbie
timestamp: September 09, 2017, 05:13:31 pm
content: The Fiskars (Later PowerWare/Eaton) UPS 08 was an online UPS from the 80's, and I think that the transformer was only used for the output for that reason. The mains was never switched straight to the output.
Can I use a 1A Bell transformer to power my arduino based door bell - Page 1
Forum section: electronics / beginners

author: amateur_25
author_rank: Regular Contributor
timestamp: December 17, 2014, 11:44:06 pm
content: Hi Guys,I have designed a Westminster theme door bell for my parents. Being old and also our house is fairly big, they can't hear the door bell.I was once told that these bell transformers aren't really suitable for driving heavy loads continuously. However my circuit only containsan lm380 audio opamp, a 2w speaker (4ohm I think), ld33cv reg, N channel mosfet, and a atmega328p chip. Will it work or will Ineed a pcb mount transformer? I'm learning towards it will work fine but I thought I'd ask.

author: Zero999
author_rank: Super Contributor
timestamp: December 17, 2014, 11:54:52 pm
content: What sort of transformer is it?You'll most likely need a bridge rectifier, a large smoothing capacitor and a voltage regulator.

author: amateur_25
author_rank: Regular Contributor
timestamp: December 18, 2014, 02:28:25 am
content: Sorry I should have specified the transformer type. STUPID!Yes I understand I will need a bridge rectifier. It's a Friedland Bell transformer Doorbell transformer D753 it outputs 8vac.I thought it would be fine but wanted to ask before I break a brand new transformer. So it should be fine right?

author: Richard Crowley
author_rank: Super Contributor
timestamp: December 18, 2014, 02:40:30 am
content: When properly rectified and filtered, your 8VAC will produce around 11VDC.You say "Arduino", but then you talk about an ATMEGA328P and a LD33CV as if you were creating your own "Arduino-like" board from scratch.Note that your LD33CV will take a maximum input of only 15V DC. So you have some breathing room there, but not an over-abundance.Did you actually MEASURE the doorbell power transformer output yourself, or did you "dry lab" it?Note also that once you rectify and filter the 8VAC dorbell power, you will need some isolating way of switching it or sensing it.That is to say, neither side of the doorbell line can be connected to Arduino ground.I would use an opto-isolator on input and output nodes.
Can I use a 512K EPROM as a replacement for a 128K one? - Page 1
Forum section: electronics / beginners

author: Midphase
author_rank: Regular Contributor
timestamp: September 17, 2024, 12:33:32 am
content: Howdy everyone,Just got me a XGecu T48 burner so I'm having some fun updating some of my vintage synth firmwares.I pulled a HITACHI HN4827128G-25 from my Korg DW-8000 and rather than erasing it, I was thinking of burning the latest firmware on a AT27C512R-45PU that I have handy and which has the same footprint.Any thoughts? Good idea? Bad idea?Unfortunately the 128K are difficult to find and kinda expensive, and since I already used the 512K to replace a 256K EPROM (I didn't actually realize I did that until I did and it's working just fine), I was wondering if I can do the same thing with the 128k?Many thanks for any info that you might be able to provide, as well as any settings I would need to use in the XGecu Pro app.

author: wraper
author_rank: Unknown
timestamp: September 17, 2024, 12:56:22 am
content: If you connect A14, A15 pins to GND, I see no reason why it would not work.

author: edavid
author_rank: Super Contributor
timestamp: September 17, 2024, 01:01:25 am
content: Quote from: wraper on September 17, 2024, 12:56:22 amOr you can just burn 4 copies of the data, then it doesn't matter what A14 and A15 are tied to.

author: wraper
author_rank: Unknown
timestamp: September 17, 2024, 01:08:34 am
content: Quote from: edavid on September 17, 2024, 01:01:25 amYes, hewever they should not be left floating in any case. Connecting them to 5V is fine too as long as you multiply the data. If they're already connected to either, then no hardware modification is needed.

author: pqass
author_rank: Super Contributor
timestamp: September 17, 2024, 01:54:12 am
content: A 27128 socket would normally have both PGM (pin 27) and VPP (pin 1) tied to Vcc. A 27512 replaces these pins with A14 and A15, respectively. Therefore, putting a 27512 into a 27128 socket will need a copy of the 27128 data on the top quarter of the 27512 (C000-FFFF).FYI: Your reference to "128K", "256K" and "512K" EPROMs are actually only 16K, 32K, and 64K, respectively.K = 27xxx where xxx/8

author: Midphase
author_rank: Regular Contributor
timestamp: September 17, 2024, 02:46:31 am
content: Thank you all.I was reading about copying the data to fit the larger EPROM, and then lo and behold somebody already did that and was kind enough to share the .bin file. I was able to use that to burn the new firmware into the synth and I was happy to see that it is indeed working well.Many thanks, I am sure I will have more questions soon as I continue to update the rest of my synths.
Can I use a MCP73831 to charge a 10.8V battery? - Page 1
Forum section: electronics / beginners

author: amin08
author_rank: Contributor
timestamp: October 30, 2017, 12:10:05 am
content: I was wondering if it's possible to charge a 10.8V LI-ION battery using Microchip's MCP73831 battery charger.Any advice or suggestion is appreciatedThanks!

author: Ian.M
author_rank: Super Contributor
timestamp: October 30, 2017, 12:25:35 am
content: No. Its a single cell charger with a maximum input voltage of 6V. While theoretically you could charge a 3S (three series cells) pack, disconnected from any load circuit, one cell at a time via its balance connector, it would take three times longer, and if the battery was ever put back into service with one or more cells charged and a cell discharged, the result would be cell damage with a risk of fire, explosion or release of toxic chemicals.To do the job right, you need a 3S charger, probably with balancing, and the required input voltage will probably be somewhere around 13V or 14V.

author: amin08
author_rank: Contributor
timestamp: October 30, 2017, 05:42:11 pm
content: Is there any IC that can perform that?

author: Zero999
author_rank: Super Contributor
timestamp: October 31, 2017, 09:09:57 am
content: Quote from: amin08 on October 30, 2017, 05:42:11 pmhttp://uk.farnell.com/linear-technology/lt3652emse-pbf/ic-battery-charger-solar-12msop/dp/1839126?mckv=01vqGHYU_dc|pcrid|78108290949|&gross_price=true&CATCI=pla-131230172469&CAAGID=14983512189&CMP=KNC-GUK-GEN-SHOPPING-LINEAR_TECHNOLOGY&CAGPSPN=pla&gclid=EAIaIQobChMI8aH-ksGa1wIVhpPtCh1-6gTPEAQYAyABEgJA_fD_BwE&CAWELAID=120173390000112371
Can I use a power pack toy transformer as a Power supply for tattoo machine? - Page 1
Forum section: electronics / beginners

author: Rpflueger
author_rank: Newbie
timestamp: August 30, 2013, 11:32:09 am
content: I have this Allstate Powerpack Toy Transformer as shown here:http://www.ebay.com/itm/Vintage-Allstate-HO-Scale-Train-Powerpack-Toy-Transformer-6030AS-Tested-Works-/310731362958?pt=Model_RR_Trains&hash=item485908528eInput 115v A.C. 60 cyclesOutput 18V A.C - 4-18V D.C. - 20V - AmpsTo track 1.5 amps maxTo access 18v A.C.Now My girlfriend is a tattoo artist. Her Powersupply went out on her mid-tattoo on a customer. She has one of those cheap china ones that come with a beginners kit.I busted out this power supply used for model trains, hooked up her tattoo machine to the 1.5 amps d.c. connectors and she was back in business... Sweet!I took a look at her cheap power supply, and decided to take out her voltage meter and wire it to the train PS, so now it reads what voltage its at while she tattoo's.. I know genius right!!This good ol made in usa power supply works like a champ.. now it reads voltage and is fairly adjustable with the "Fast-Off" switch. Works in Reverse mode and Forward, ( I think This makes little difference either direction is good) I wired her foot pedal between the gun and the PS... Im so proud of myself this power supply will work till im dead!!OKay its ghetto.. a bit janky, old as a dinosaur, and rigged to work. I think it has got character, she thinks its a Piece of Crud and wants a new digital readout Dual power supply with liner and shader speed settings etc. cost arond 25-30 dollars.I bust out the spray paint and give it a nice coat of Sail Blue - Add some gloss white accent's and ViolA!! Looks nice she says.. 100% better!But it doesn't have a place to plug in her gun or pedal.. its not digital.. and the variance is either all the way fast or barely moving..Im knee deep into this project now, there aint no way im giving in.Problem: How to wire the pedal and Gun Plugs? DO I need a better variable POT to have more control of the voltage for tuning her gun? How would you do this? any advice is appreciated.Solution: ALready ordered her a new Power Supply as shown here:http://www.ebay.com/itm/321192912528?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649Thanks for your help!

author: MrAureliusR
author_rank: Unknown
timestamp: August 30, 2013, 04:58:44 pm
content: In the future please resize your pictures down to 1024x760 or similar, huge photos make it very difficult to see what's going on, even on my 1440x900 monitor. That said, welcome to the forum! Hope you keep coming back.
Can I use a scope probe to inject RF from my sig gen?? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: December 01, 2017, 03:38:00 pm
content: Can I use a normal X1 / X10 oscilloscope probe on the 50 Ohm output of my HP sig gen to inject RF into a dead transceiver for fault tracing? The service manual says to inject a 14MHz signal at about -110dBm . If the fault is after the IF the IF is circa 70Mhz (Kenwood TS-590 with dual IF paths). If not what can I do for a suitable probe on the end of the co-ax from the sig gen at these frequencies? Thanks.

author: Ian.M
author_rank: Super Contributor
timestamp: December 01, 2017, 03:59:03 pm
content: Not in any predictable fashion - the scope probe coax is deliberately lossy, so even on x1 you'll be guessing the output level at the probe tip, and on X10 it will be a highly frequency dependent unknown attenuator.Also -110dBm is 10pW (picoWatts), so even if your generator output level is only 7mV RMS, you'd have to stack four 50R matched 20dB attenuators to get its output down to an appropriate level.

author: TheDane
author_rank: Regular Contributor
timestamp: December 01, 2017, 04:05:08 pm
content: What kind of probe do you have?If a normal probe to you is an active type, then the answer is no - as it has most likely an amp inside it.If it is a passive 100MHz x1 probe with a 14MHz signal, then most likely yes - is my experience. Make sure there is no attenuation (it is an active short from input to output), unless you want/need it. -110dBm is not for beginners.I recommend reading about some myth regarding probes, it's quite enlightening, especially the 3dB part in 1):http://www.electronicdesign.com/test-measurement/11-myths-about-oscilloscope-probesquote: "A widely accepted rule of thumb is to use a probe with 3X to 5X the clock frequency or the fastest toggle rate in a digital system. This makes it possible to capture the third or fifth harmonic of the fundamental frequency of the clock or digital signal, resulting in a signal on the screen of the oscilloscope that more accurately represents the true signal with square-like edges. Another useful rule of thumb is that BW × Tr = 0.35 (for 10-90 Tr). Using this rule of thumb, one can either determine the needed bandwidth to measure a given rise time or the fastest edge that can be measured for a probe of a certain bandwidth."

author: james_s
author_rank: Super Contributor
timestamp: December 01, 2017, 11:58:18 pm
content: I seriously doubt it's an active probe, those are specialty hardware that one is not typically going to have unless they know what it is and why they need it.I see no reason why a scope probe can't be used to inject RF. It may not be ideal, it may not give easily quantifiable results, but RF will come out the tip of the probe and it won't hurt anything.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 02, 2017, 05:06:15 am
content: If all you want to do is poke some RF into the input & see if it comes out somewhere else, why not?If you wanted to input a known signal level, youwould not use a 'scope probe.
Can I use a switching power supply to power a circuit that reads a thermocouple? - Page 1
Forum section: electronics / beginners

author: WarFreak131
author_rank: Contributor
timestamp: August 25, 2020, 02:47:47 pm
content: I am planning on building a circuit to measure the voltage on a thermocouple and display it on an LCD. I'm pretty new to using thermocouples so I have been doing research on them. I will be using the LTC1049 and LT1025A to measure/amplify the thermocouple signal (as per the sample circuit in the datasheethttps://www.analog.com/media/en/technical-documentation/data-sheets/1049fb.pdf).My concern is that the SMPS will introduce noise into the circuit that may be on the same order of magnitude as the thermocouple voltage, and may cause inaccurate readings. Are these concerns legitimate? And if so, how can I mitigate them? I'd prefer to keep the SMPS due to it's light weight, but I can change that if necessary.

author: jmelson
author_rank: Super Contributor
timestamp: August 25, 2020, 03:57:57 pm
content: Yes, your concerns are correct. Thermocouples give VERY small voltages, and switching noise could actually be orders of magnitude GREATER than the thermocouple voltage. Very good filtering of the incoming power will be required. An L-C filter where the power comes into the board is what you want. A good instrumentation amplifier can help.Jon

author: tszaboo
author_rank: Super Contributor
timestamp: August 25, 2020, 04:00:19 pm
content: Check PSRR of the opamp on the switching frequency and harmonics. Probably place an RC filter on the supply line of the opamp. Keep noisy power lines away from signal. Forget chinese smps modules.
Can I use an FM variable cap for a magnetic loop antenna for RX? - Page 1
Forum section: electronics / beginners

author: azigta
author_rank: Regular Contributor
timestamp: September 04, 2016, 04:24:42 pm
content: Hi, In the next few weeks I'm going to recieve my very first non commercial radio, a chinese rtl sdr that can go from 100khz to 1.7ghz. So I decided to make an antenna, since I want to recieve hf for swl.I sawthisvideo and I decided to make that antenna. I know how many meters of copper tubbing I have to buy and everything , but I have a little problem.In the video, the guy uses an air variable capacitor. And from what I've read on some forums, that is an essential piece of the project. I also read that it is important to put a capacitor that has a great gap between plates if you're going to transmit. But since I'm not going to transmit at all, I was thinking if I could use a regular FM radio variable capacitor that I desoldered time ago from an FM radio.I took some pictures of the capacitor so you guys can see how is it. I've seen similar capacitors but with different pins, so I thought It would be a better idea to take some pictures.Here they are:Picture 1,picture 2,picture 3As you can see, is the kind of capacitor that you find on an analog fm radio.In the third picture you can see that 2 tabs are located one on the top of the other, so if you look at the second picture it might be hard to tell if there's one or two tabs there.One of the tabs was already cutted when I desoldered it, but is not too short, I can solder on that (I'm describing the left top tab that you can see in the first image)Also, I have a multimeter that can measure capacitors but I can't measure this one. Not a slight change on the meter when I turn the screws or the "big" shaft (in the center of the box, you can see it in the third image, that's the "shaft")When I turn the trimmers they don't have a limit. The big shaft does have a minimum and a maximum limit.So, Can I use this for a magnetic loop antenna if I'm only going to recieve with it? if so, where would I connect the loop? I don't know how to measure this thing so I don't know where do I have to connect it.Maybe someone here knows about this stuff and can help meThanksEdit: After a lot of searching, it turns out that I can! here's a link to a good tutorial on how to make a magnetic loop antenna for SWL with an fm capacitorhttp://www.kr1st.com/swlloop.htm
Can I use an LM311 in a 4MHz crystal oscillator? - Page 1
Forum section: electronics / beginners

author: Peabody
author_rank: Super Contributor
timestamp: April 01, 2024, 04:54:42 am
content: I'm not sure what to look for in the datasheet. I have the crystal and three LM311s. Is there any chance one of them will work, and be stable? This is just for a personal project, not a commercial design.

author: Konkedout
author_rank: Frequent Contributor
timestamp: April 01, 2024, 05:11:57 am
content: I think it work not at all or poorly at best.I just checked the datasheet and confirmed my memory that the LM311 response time is 200 nSec. That is probably a typical number (not worst case maximum.) But a complete cycle (one period) of a 4 MHz oscillator is 1/(4MHz) = 250 nSec. The output needs to switch both up and down during one period. This means to me that the response time MUST be no more than 250 nSec/2 = 125 nSec maximum, and probably less than that.I think that if you want to use a comparator for this purpose, you probably ought to use one with a response time of 50 nSec or less. I have never designed a crystal oscillator and I am not in a position to give you a design unless I were to spend some time working on it.When using a crystal be careful not to overdrive it....

author: Peabody
author_rank: Super Contributor
timestamp: April 01, 2024, 01:41:44 pm
content: Thanks very much. That's what I suspected. I was just hoping a comparator I had on hand would work.

author: Benta
author_rank: Super Contributor
timestamp: April 01, 2024, 06:32:25 pm
content: You want to drive a crystal with a linear amplifier, not whomp it with a comparator output.One of the best parts for this is the SN74LVC1GX04:https://www.ti.com/lit/ds/symlink/sn74lvc1gx04.pdf
Can I Use Dual Polarity Supply on Single Supply Load? - Page 1
Forum section: electronics / beginners

author: penmarker
author_rank: Contributor
timestamp: September 09, 2017, 05:16:13 am
content: I am planning to do a minor mod on my phono preamp. It comes with a walwart 12V power supply and I want to use a linear regulated power supply.Looking through eBay there are quite a few LM317/337/LT1083/84 based circuits.For LM317/337 there are mostly dual rail circuits with adjustable +V/0/-V. Is it possible for me to use it for my phono preamp by tapping the +12/-12? Should the ground be connected too? What happens if its not connected?http://www.ebay.com/itm/262339244872Most of the searches I've done returns results for how to split single rail to dual rail with caps and resistors, but not how to use a dual rail supply with a single rail load.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: September 09, 2017, 07:44:37 am
content: You can use the positive output on its own, connecting between 0v and +V.I think you'll find this type of board requires a transformer with a center-tapped secondary though. It would probably work with a single winding connected between the input center and one 'hot' terminal but in that case you would only have half wave rectification. Which might not be ideal.

author: penmarker
author_rank: Contributor
timestamp: September 09, 2017, 07:54:17 am
content: Center tapped transformers might be a little hard to find cheaply, so my previous amp project that required a CT 28V transformer was achieved by connecting the + and - of two transformer outputs to achieve a center tap like this.If I'm only going to be using the +V/0 and not the -V/0, would it would be preferable to use a single LM317 instead of the dual polarity 317/337?One more question: If I want to get 12V DC, should the transformer output be 12V or a little higher like 15V?

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: September 09, 2017, 11:03:14 am
content: "If I want to get 12V DC, should the transformer output be 12V or a little higher like 15V?"There is no simple answer to this as it depends on the transformer's internal resistance, the reservoir cap value and the load current in quite a complex way. 12Vac will give about 1.4X12 - 0.7 Vdc offlload -about 16Vdc - but that will drop to nearer 12V under full load. In other words probably enough for a featherweight load but regulation will be lost under substantial loads.15Vac will give about 20V at the regulator input and thus be a safer bet, as it will always be enough to allow for the regulator drop.The main disadvantage of upping the supply to a linear regulator is that the heat dissipation goes up by leaps and bounds. Unlikely to be a problem with the current drawn by a preamp though.
Can I use EP (exposed pin) / heatsink of SOT-223 voltage regulator for voltage? - Page 1
Forum section: electronics / beginners

author: sofakng
author_rank: Regular Contributor
timestamp: November 17, 2022, 10:04:21 pm
content: I'm looking at using theON Semi NCP1117LPas a 3.3v voltage regulator.However, the PCB design uses a different regulator and also uses the exposed pin (heatsink) connected to the output pin of the regulator. Normally this exposed pin/heatsink is connected to ground so is this safe to do? I've looked in the datasheet on my replacement regulator (NCP1117LP) and I can't find anything mentioned.Also, if the datasheet specifies 10 uF bypass (?) capacitors is it safe to use a larger value (ie. 100 uF) ?

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 17, 2022, 10:51:49 pm
content: The center pin is always connected to the bottom pad in DPAK and SOT223 packages.In some regulators it's gnd, in others it's vout... Just remember they're the same pin and design the board accordingly.This is for TO220, but it's the same:In the NCP1117, the center pin is Vout, so don't connect to Gnd neither the bottom pad or the center pin.Check continuity between pins with a DMM if you have doubts.

author: mariush
author_rank: Super Contributor
timestamp: November 17, 2022, 11:11:32 pm
content: Some 1117 linear regulators are very sensitive about the ESR of the output capacitor. Some require a capacitor with ESR between 0.1 ohm and 1 ohm, so if the circuit use ceramic capacitors on the output, you have to be careful.For example, your NCP1117LP says this about the output capacitance :https://www.onsemi.com/pdf/datasheet/ncp1117lp-d.pdf(page 10)QuoteI'd say a 47uF ... 100uF 10v--25v standard 105c rated capacitor will have around 0.1 .. 0.3 ohm ESR so it would be OK throughout the whole temperature ranges.The tab on your NCP1117LP is connected to pin 2, which is "output", it says so right there on first page in the datasheet.There are lots of 3.3v regulators in that package that will have the tab as input voltage.You'll also want to determine if the regulator on the board is an adjustable version or a fixed 3.3v versionFor example, here's 43 linear regulators fixed 3.3v output, in SOT223 packages :https://www.digikey.com/short/fzf9dq1fAnd 34 adjustable regulators in SOT223 :https://www.digikey.com/short/n1r8ffqq
Can I use NFC as RFID - Page 1
Forum section: electronics / beginners

author: buzzybee191@gmail.com
author_rank: Newbie
timestamp: November 30, 2019, 11:18:18 am
content: So I have a door entry system which uses RFID tags. Could I get a NFC sticker and use it as a RFID tag

author: Fred27
author_rank: Unknown
timestamp: November 30, 2019, 12:06:51 pm
content: There are a few different standard, usually spilt into two frequencies - 125kHz or 13.5Hz. it really depends on the system you're using.

author: Rerouter
author_rank: Super Contributor
timestamp: November 30, 2019, 12:15:08 pm
content: the NFC tags tend to use 13.56MHz, generally produced by mifare and using there standard, if your reader supports that, then it should work,Just kind of hoping that it doesn't just scrape the UID for a door system... these types of tags can be programmed with key strings secured by actually block keys, (practically every NFC tag out there is reprogrammable)
Can i use this Diode? - Page 1
Forum section: electronics / beginners

author: almamater
author_rank: Regular Contributor
timestamp: February 14, 2022, 11:16:01 am
content: Hello, My kitchen hood (Teka) has stopped working.I removed the board and found a damaged SS310 Diode.The board is simple, it has the 220V AC that it converts to DC and then transforms into 12V for the circuit where the SS310 Diode was, this circuit has a ULN2003A that controls a few Relays:I highlighted the Diode in the image above with a red line, as I don't have anySS310, and just to test, I used anSS14i had here and the board turned on without any problem, the display and the relays also work.The problem is that diodes have different characteristics, one is 100V and the other 40V as well as 3A to 1A..Do you think it's better to buy an equal diode (100V-3A)? or can i leave this one? The current that passes through here doesn't seem to be much.. because (i assume) that this part of the circuit is just to control the ULN2003 and the relays.P.S.: In my area, the closest i can find (of the SS310) is the SS510, 5A, 100V..Thanks

author: bob91343
author_rank: Super Contributor
timestamp: February 14, 2022, 05:33:36 pm
content: As long as the replacement part has higher ratings than the original, you are good to go. Don't replace a 100V part with a 40V part. Diodes are cheap.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 14, 2022, 05:52:53 pm
content: I wonder how it failed in the first place; that's not a part/location that should be prone to failure.Given the output is about 12V, I doubt the 40V rating matters, or the 3A rating for that matter, if it's indeed just powering the relays shown. Best to replace with same or better, of course.Tim

author: SeanB
author_rank: Super Contributor
timestamp: February 14, 2022, 06:38:32 pm
content: Diode probably just failed, and yes a 3A one should be there, though as this is a low power circuit the 1A version will probably work well enough.

author: rpiloverbd
author_rank: Regular Contributor
timestamp: February 16, 2022, 01:05:44 pm
content: My suggestion is to find the same diode. Or something equivalent. The one you actually had is a 100V schottky diode. So, if you're thinking of an alternative, you should chose another 100v schottky diode.
Can I use this for both EEPROM's and Microcontrollers? - Page 1
Forum section: electronics / beginners

author: Midphase
author_rank: Regular Contributor
timestamp: May 04, 2024, 04:24:48 pm
content: Howdy. I need to program an ATMega644p, but I also would like to be able to write to EEPROM's to update the firmware of several vintage synths that I have. I am leaning toward purchasing the XGecu T48 [TL866-3G] Programmer and I was wondering if it would work for both uses?https://www.amazon.com/dp/B0B59959PR/?coliid=ILHR996DWG7WD&colid=6QC7U6MBJ09D&psc=1&ref_=list_c_wl_lv_ov_lig_dp_itSorry for the total noob question but when it comes to actually programming chips, I am completely ignorant.Another concern that I had with the XGecu T48 is that the ATMega644p is not listed, however the ATMega644pa is listed. Judging by the data sheet that I found on Mouser, they appear to be pretty much identical from what I can tell, but is device compatibility based on the hardware or the software?Many thanks for any info you're willing to provide!

author: Kleinstein
author_rank: Super Contributor
timestamp: May 04, 2024, 04:37:42 pm
content: The 2 AVR versions should be pretty much compatible, if there is a difference at all and not just the A missing in the listing.The difference would be mainly a minor difference in the power consumption and maybe a different µC ID. So one may have to tell the programmer to accept the different ID or ignore a difference in the ID.

author: Midphase
author_rank: Regular Contributor
timestamp: May 05, 2024, 01:37:59 am
content: That's what I figured, thank you!
Can I use this for that? - Page 1
Forum section: electronics / beginners

author: OpenCircuit
author_rank: Regular Contributor
timestamp: March 24, 2017, 03:22:43 am
content: Found a failed transistor in a power supply I am working on. Transistor (16N50C3) drain terminal shorted to ground where it mounted and popped the fuse. Wondering if any of the ones I have below would be a suitable temporary in my ATX switching power supply until the exact replacements arrive? Before I do I was hoping someone with a bit more knowledge could comment.Failed 16N50C3:https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwjDtu-Qke7SAhUU-2MKHQvAAEkQFggcMAA&url=http%3A%2F%2Fwww.infineon.com%2Fdgdl%2FInfineon-SPP_I_A16N50C3-DS-v03_02-en.pdf%3FfileId%3Ddb3a3043163797a6011637e882e70061&usg=AFQjCNGoUUPvQvy5oWNEkiFMB7p619dj5A&sig2=PQSTNCRae0slTHTPSYSZig&cad=rjaWould like to replace with (:https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiCz8iOku7SAhUD5mMKHY32CSMQFggaMAA&url=http%3A%2F%2Fwww.vishay.com%2Fdocs%2F88549%2Fbyq28e.pdf&usg=AFQjCNG-icAyFVZp-zkafSZj--8gmlUK_w&sig2=9xM3i9uHp6PKLNwl2JEXrQ&cad=rjaORAlso found these in the TO-220 form:https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&sqi=2&ved=0ahUKEwiepa-Vlu7SAhVG0YMKHWItAkMQFggaMAA&url=http%3A%2F%2Fwww.st.com%2Fresource%2Fen%2Fdatasheet%2Fl78.pdf&usg=AFQjCNHYUVYe8v1D6uqLAR9ijqGKykpang&sig2=yolVNN86-hV4m5_pLDeIPw&bvm=bv.150475504,d.amcor lastly this E13009:https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwiEkI-dl-7SAhVL74MKHRkNBmsQFgggMAE&url=https%3A%2F%2Fwww.onsemi.com%2Fpub%2FCollateral%2FMJE13009-D.PDF&usg=AFQjCNGW_KdV3Ol9xOeKAK42_t8tdw_1QA&sig2=0teNXHFSZgFm7qXYThAA0g&bvm=bv.150475504,d.cGc&cad=rja

author: OpenCircuit
author_rank: Regular Contributor
timestamp: March 24, 2017, 03:50:53 am
content: Quote from: blueskull on March 24, 2017, 03:36:20 am

author: OpenCircuit
author_rank: Regular Contributor
timestamp: March 24, 2017, 04:03:58 am
content: This?https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjKxZDjoO7SAhVKxYMKHTpMDoEQFggcMAA&url=http%3A%2F%2Fwww.datasheetspdf.com%2Fdatasheet%2FK18A50D.html&usg=AFQjCNGG7WfbnABap3t1f36H7x8lEKyebw&sig2=uXuycTMRoZKVT_Skfi3RVQ
<deleted> - Page 1
Forum section: electronics / beginners

author: cooleb09
author_rank: Newbie
timestamp: October 24, 2017, 12:55:54 am
content: <deleted>

author: Rerouter
author_rank: Super Contributor
timestamp: October 24, 2017, 01:30:39 am
content: The better approach would be to use an op amp buffer to sum the shunt input with a control voltage, you increase your control voltage, the shunt current looks higher, and it current limits lower, and vice versa,The inductor will already be doing current smoothing for you, what it wont do while current limiting is voltage regulation, this is where your idea for a linear regulator after its output would come in to play.Be aware this will only function as a proper current limit for a Buck regulation approach, assuming the device allows 0 PWM when above current limit threshold. for a boost, current would still flow through the inductor,
Can I use two A4949 (3-phase motor driver) in parallel if I want it reversible? - Page 1
Forum section: electronics / beginners

author: dusan
author_rank: Regular Contributor
timestamp: May 17, 2025, 02:00:22 pm
content: I have small 3-phase brushless DC motor, I wanted some simple driver. I found A4949:https://www.allegromicro.com/-/media/files/datasheets/a4945-a4949-datasheet.pdfBut it is not reversible, I want to make it reversible. Can I just use 2 chips and use different phase order in second chip to make it reversible?

author: wraper
author_rank: Unknown
timestamp: May 17, 2025, 02:09:28 pm
content: It may be possible depending on how IC handles it's outputs with 0% PWM but it would be an absolutely idiotic design prone to blowing up. Just use an IC that works in both directions.

author: dusan
author_rank: Regular Contributor
timestamp: May 17, 2025, 03:40:56 pm
content: I was looking but couldn't find any.

author: wraper
author_rank: Unknown
timestamp: May 17, 2025, 03:50:46 pm
content: DRV11873 for example
Can i use uart0 gpio pins 43 and 44 in esp32 s3 for projects?  - Page 1
Forum section: electronics / beginners

author: Rishles69@
author_rank: Regular Contributor
timestamp: January 04, 2025, 07:12:37 am
content: Can i use GPS modules on UART0 gpios 43 and 44 of esp32-s3? In official datasheet, it says I could use it as a normal gpio. So my question is, can I actually connect a gps module to those pins? If possible, what measures should I take in order to use it for my project? Can anyone conform this?

author: tooki
author_rank: Super Contributor
timestamp: January 04, 2025, 01:00:59 pm
content: By default, the MCU’s boot messages are output to UART0 (and to the native USB). That could cause issues with the GPS (you haven’t stated what kind of interface the GPS uses so impossible to say for sure). You can change this with an efuse setting so it only outputs to the native USB.But unless you are short on pins, use something else for GPS and at most put something non-critical (like status LEDs or whatever) on the UART0 pins.

author: Rishles69@
author_rank: Regular Contributor
timestamp: January 05, 2025, 12:26:32 am
content: Well thanks for the help. By the way, I'm using ATGM336h gps module which uses the UART interface to communicate. What will happen if I disconnect esp32-s3's uart 0 pins from the gps module while uploading the code? Or can I use 2 push buttons on those pins with pull ups or pull downs?

author: tooki
author_rank: Super Contributor
timestamp: January 07, 2025, 02:42:12 pm
content: The problem has nothing to do with programming, but with the fact that by default, you get a boot message every time the MCU starts up, including every time you turn the device on. Just because you don’t have a computer connected with which to read those messages doesn’t mean they aren’t being written.The easiest thing is to just use different pins if you have them. As I said, if you have “dumb” things you are connecting, like switches or LEDs, put those on the UART0 pins and put the GPS on unencumbered pins.If you absolutely have no free pins and no way to reassign other pins, then disable the boot message with the efuse setting, and then program using the native USB rather than UART.
Can LM2940/to-263 (three pins +tab) work in d2pak (two 2 pins + tab) footprint? - Page 1
Forum section: electronics / beginners

author: julian1
author_rank: Frequent Contributor
timestamp: October 01, 2024, 01:02:11 am
content: The datasheet shows pin 2 and the center tab (pin4) are both gnd.Can one tell, or guess if this connection made by the internal metal lead frame?https://www.ti.com/lit/ds/symlink/lm2940c.pdf

author: Kurets
author_rank: Regular Contributor
timestamp: October 01, 2024, 04:52:51 am
content: TO220 and D2PAK are almost the same package. Internally the die is soldered and electrically connected to the heatsink tab. So electricallt the substitute can be made.I actually knew a guy who modified TO220 ti SMD by cutting of the tab and forming the leadS by hand. Can't say this is recommended due to risk of damage to the device though.
Can my dynamic design be correct given it has no PMOS transistor? - Page 1
Forum section: electronics / beginners

author: NickDaMan
author_rank: Newbie
timestamp: July 21, 2018, 09:46:13 pm
content: I am working on an assignment and I am very confused with it.As far as I understand, a dynamic design will charge/discharge a load capacitor on the pre-charge phase (clock = LOW) and follow a desired design logic on the evaluation phase (clock = HIGH). This is achieved with the use of a PMOS transistor to read clock signal in pre-charge phase and NMOS transistors for the evaluation phase.However, on my assignment, the clock is also part of the logic, and therefore the dynamic design is not as straight-forward as all the examples I have found and understood, where there we have a PMOS for the pre-charge phase and an NMOS system for the evaluation phase.Here is the question:I devised that the equation I am working with is Y = (A⊕B)⊕CWith the following truth table:From the truth table above I singled out all the combinations that leads to Y = 0, to end with the following function (using ! to represent NOT):!Y = !C(!A!B + AB) + C(!AB + A!B)This will be the NMOS part of the design, or the evaluation part.I then drew the schematic as follows:However, I find myself questioning if this is the right design, given the lack of any PMOS transistors.Please, any advise or resources would be great!Cheers

author: amyk
author_rank: Super Contributor
timestamp: July 22, 2018, 03:18:31 am
content: You're missing the pullup part, which will have a PMOS connected to the clock to precharge the output. As is, your circuit shorts the supply whenever the clock is high and the output is to be low.
Can not identify an IC problem. - Page 1
Forum section: electronics / beginners

author: ma.algendy
author_rank: Newbie
timestamp: June 21, 2017, 10:00:40 pm
content: Hello Everyone,my brother bring me an small fm radio the can also play mp3 from usb or any memory card to repair it .the battery was blown up and it was not working by any other way ( DC or even directly from AC ). there are two main ic on the board and unfortunately i find what are they even after search the labels that is written on them .the first on has a label ( JL AB525CG4A18.1-85 ) it seems like all the circuit voltage is coming from this one .the second one has a label (8175 062q 5TCA) and it take the signal that comes from the antenna .does any one has any way to help me identify those two ic's specially the first one?

author: mdszy
author_rank: Unknown
timestamp: June 21, 2017, 10:21:15 pm
content: Quote from: ma.algendy on June 21, 2017, 10:00:40 pmYou hooked a radio/mp3 player directly to the mains across its battery terminals??And that didn't blow it up???

author: ma.algendy
author_rank: Newbie
timestamp: June 23, 2017, 09:04:15 am
content: sorry , i meant connecting it through an adapter from AC not using the internal battery or the other 4 AA batteries .

author: CJay
author_rank: Super Contributor
timestamp: June 23, 2017, 11:26:47 am
content: Pictures of the ICs would be useful because clues as small as the font style can help.

author: amyk
author_rank: Super Contributor
timestamp: June 23, 2017, 11:50:46 am
content: JL logo with very long part number? I think I know the manufacturer but not the part.See my last post in this thread:https://www.eevblog.com/forum/projects/need-help-to-identify-this-chip/(Some of the links there are sadly dead, but Googling the company name still works.)

author: ma.algendy
author_rank: Newbie
timestamp: June 24, 2017, 10:22:28 am
content: amyk , that is exactly what i was looking for . it is the same company .however , i still need to have some information on the chip itself .i have sent a feedback to the company and i hope they answer my message soon .Thanks for your help.